EP2151004A2

EP2151004A2 - Electrochemical cells and methods for generating fuel

Info

Publication number: EP2151004A2
Application number: EP08755040A
Authority: EP
Inventors: Gerardine G. Botte
Original assignee: Ohio University; Ohio State University
Current assignee: Ohio University; Ohio State University
Priority date: 2007-05-04
Filing date: 2008-05-04
Publication date: 2010-02-10
Also published as: WO2009045567A3; WO2009045567A2; EP2151004A4

Abstract

An electrochemical cell for causing a reaction that produces hydrogen or a fuel cell is disclosed, the electrochemical cell comprises a first electrode comprising at least one layered electrocatalyst formed of at least one active metal layer deposited on a carbon support, wherein the metal layer is active to a target species The layered electrocatalyst has a first metal plating layer has a thickness ranging from 10 nanometers to 10 microns and a second metal plating layer at least partially deposited on the first metal plating layer, wherein the second metal plating layer has a thickness ranging from 10 nanometers to 10 microns The cell also has a second electrode comprising a conductor, a basic electrolyte, ammoma, ethanol, or combinations thereof, and an electrical current in communication with the first electrode.

Description

^ J _J

SPECIFICATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to the United States provisional application having application serial number 60/916,222, to the United States provisional application having the application serial number 60/974,766, to the PCT application WO/2006/121981, which in turn claims priority to the United States provisional application having serial number 60/678,725, and to the utility application having the application serial number 10/962,894, which in turn claims priority to the United States provisional application having serial number 60/510,473 , the entirety of which are incorporated herein by reference.

[0002] A

FIELD

[0003] The present embodiments relate to an electrochemical cell for causing a reaction that produces hydrogen through the oxidation of ammonia, ethanol, or combinations thereof.

BACKGROUND

[0004] A need exists for an electrochemical cell able to oxidize ammonia, ethanol, or combinations thereof in alkaline media continuously.

[0005] A further need exists for an electrochemical cell that utilizes an electrode having a unique layered electrocatalyst that overcomes the positioning of the electrode due to surface blockage.

[0006] A need also exists for an electrochemical cell that utilizes a layered electrocatalyst with a carbon support that provides a hard rate of performance for the carbon support.

[0007] The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The detailed description will be better understood in conjunction with the accompanying drawings as follows: [0009] Figure Al depicts an embodiment of the present electrochemical cell.

[00010] Figure A2 depicts an exploded view of an an embodiment of an electrochemical cell stack.

[00011] Figure A3 shows adsorption of OH on a Platinum cluster.

[00012] Figure A4 shows experimental results of the electro-oxidation of ammonia on a Pt electrode, using a rotating disk electrode.

[00013] Figure A5 shows results of microscopic modeling of the electro-adsorption of OH, indicating that if the sites were available, the adsorption of OH would continue producing higher oxidation currents

[00014] Figure A6 shows a representation of the electro-oxidation mechanism of ammonia on a Pt electrode. As NH3 reaches the Pt surface it competes with the OH" electro- adsorption. Since the Electro-adsorption of OH" is faster on Pt the active sites of the electrode get saturated with the OH adsorbates causing deactivation of the electrode.

[00015] Figure A7 shows shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating and operation.

[00016] Figure A8 shows SEM photographs of the carbon fibers before plating and after plating.

[00017] Figure A9 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the performance of the carbon fiber electrodes with different compositions.

[00018] Figure AlO shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the loading of the electrode, with low loading 5 mg of total metal/cm of carbon fiber and high loading 10 mg of metal/cm of carbon fiber.

[00019] Figure Al l shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing differing electrode compositions at low loading of 5 mg of total metal/cm of fiber. Electrode compositions include High Rh, Low Pt (80% Rh, 20%

Pt), and low Rh and high Pt (20% Rh, 80% Pt).

[00020] Figure A12 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, with differing ammonia concentration, indicating that the concentration of NH3 does not affect the kinetics of the electrode.

[00021] Figure A13 shows cyclic voltammetry performance of Effect of solution at 25°C, with differing OH concentration, indicating that a higher the concentration of OH causes faster kinetics.

[00022] Figure A14 shows cyclic voltammetry performance of IM ethanol and IM KOH solution at 25°C, indicating that the present electrochemical cell is also useable for the continuous oxidation of ethanol.

[00023] Figure A15 shows energy (a) and Power balance (b) of an ammonia electrochemical cell, exhibiting a low energy consumption compared to that of a commercial water electiolyzer.

[00024] Figure Al 6 depicts an embodiment of a method for making the present electrochemical cell.

[00025] The present embodiments are detailed below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[00026] Before explaining the present apparatus in detail, it is to be understood that the apparatus is not limited to the particular embodiments and that it can be practiced or carried out in various ways.

[00027] The present embodiments relate to an electrochemical cell for causing a reaction that produces hydrogen from the oxidation of ammonia, ethanol, or combinations thereof.

[00028] Conventional hydrogen production is expensive, energy inefficient, and creates unwanted byproducts.

[00029] The present electrochemical cell provides the benefit of continuous, in-situ generation of hydrogen through the oxidation of ammonia, ethanol, or combinations thereof. The present electrochemical cell produces hydrogen through the oxidation of both ammonia and ethanol, with a faradic efficiency of 100%. In both cases, the reaction that takes place at the cathode is the reduction of water in alkaline medium, through the following reaction: [00030] 2H.O + 20- → H₁ + WH^' E" - 0,S2 V vs SHE

where SHE is a standard hydrogen electrode.

[00031] Hydrogen is the main fuel source for power generation using fuel cells, but the effective storage and transportation of hydrogen presents technical challenges. Current hydrogen production costs cause fuel cell technology for distributed power generation to be economically non-competitive when compared to traditional oil-fueled power systems. Current distributed hydrogen technologies are able to produce hydrogen at costs of $5 to $6 per kg of H2. This high production cost is due in part to high product separation/purification costs and high operating temperatures and pressures required for hydrogen production.

[00032] Using current technologies, hydrogen can be obtained by the partial oxidation, catalytic steam reforming, or thermal reforming of alcohols and hydrocarbons. However, all of these processes take place at high temperatures and generate a large amount of COχ as byproducts, which must be removed from the hydrogen product. Most of these COχ byproducts cause degeneration of fuel cell performance due to poisoning of the fuel cell catalysts. The removal of these byproducts from the fuel stream is complicated, bulky, and expensive.

[00033] Currently, the cleanest way to obtain pure hydrogen is by the electrolysis of water. During the electrolysis of water electrical power (usually provided by solar cells) is used to break the water molecule, producing both pure oxygen and hydrogen. The disadvantage of this process is that a large amount of electrical power is needed to produce hydrogen. The theoretical energy consumption for the oxidation of water is 66 W-h per mole of H^Λ produced (at 25 ⁰C). Therefore, if solar energy is used (at a cost of $0.2138/kWh), the theoretical cost of hydrogen produced by the electrolysis of water is estimated to be $7 per kg of H2.

[00034] The present electrochemical cell overcomes the costs and difficulties associated with the production of hydrogen, by enabling continuous, controllable evolution of hydrogen through the oxidation of plentiful and inexpensive feedstocks that include ammonia and/or ethanol.

[00035] Plating of carbon fibers, nano-tubes, and other carbon supports is a difficult task that is problematic due to the relatively low electronic conductivity of these materials. The low conductivity of carbon supports can cause a poor coating of the surface of the support, which can be easily removed. The electronic conductivity of carbon fibers and other carbon supports decreases along the length from the electrical connection. Therefore, the furthest point of contact to the electric connection transfers a low current when compared with the closest point to the electric contact.

[00036] The present electrochemical cell advantageously utilizes a unique layered electrocatalyist that provides electrodes with uniform current distribution, enhanced adherence and durability of coating, and overcomes surface coverage affects, leaving a clean active surface area for reaction.

[00037] It was believed that the surface blockage caused during the ammonia electrolysis in alkaline medium was due to the presence of elemental Nitrogen, according to the mechanism proposed by Gerisher:

? I NH + M τ^"-^"L-> IVfNiF s 2 f MNH₃ +OH ^z± MNH _j -i- HjO + e^" ! 2 ( MNH . ÷ QW ϊi→MNE +I1O + c^" ) <^rds)

M,N,H_? + 2OH^" ^=±M,N, +2H,O + 2e^*

Deacti v ali on React? o u :

/ v \

2| MNB •+- OH ^{' ™}±=? MN + U _tO ÷ e^" )

where M represents an active site on the electrode.

[00038] The present electrochemical cell incorporates the demonstrations of two independent methods indicating that the proposed mechanism by Gerisher is not correct, and that OH needs to be adsorbed on the electrode for the reactions to take place. Furthermore, the electrode is deactivated by the OH adsorbed at the active sites.

[00039] Results from molecular modeling indicate that the adsorption of OH on an active Pt site is strong (chemisorption) and can be represented by the following reaction:

Pt,_c -f- OH^" o Pt_w - Oϊr_{fβd j} + e^"

[00040] Figure A3 shows a bond between OH and a platinum cluster. The system was modeled using Density functional Methods. The computations were performed using the B3PW91 and LANL2DZ method and basis set, respectively. The binding energy for the Pt-OH cluster is high with a value of- 133.24 Kcal/mol, which confirms the chemisorption of OH on a Pt cluster active site.

[00041] Additionally, results from microscopic modeling as well as experimental results on a rotating disk electrode (RDE) indicate that the adsorption of OH is strong and responsible for the deactivation of the catalyst.

[00042] Figure A4 compares the baseline of a KOH solution with the same solution in the presence of OH. The curves indicate that the first oxidation peaks that appear at about - 0.7 V vs Hg/HgO electrode were due to the electro-adsorption of OH.

[00043] Figure A5 shows a comparison of the predicted results (by microscopic modeling) with the experimental results for the electro-adsorption of OH. The results indicate that the model predicts the experimental results fairly well. Furthermore, an expression for the surface blockage due to the adsorption of OH at the surface of the electrode was developed (notice that the active sites for reaction theta decay with the applied potential due to adsorbates). If the surface were clean (see results model without coverage), the electro-adsorption of OH would continue even at higher potentials, and would occur more rapidly.

[00044] Compiling the experimental results with the modeling results, the following mechanism for the electro-oxidation of ammonia in alkaline medium is proposed: First the adsorption of OH takes place. As the ammonia molecule approaches the electrode, it is also adsorbed on the surface. Through the oxidation of ammonia, some OH adsorbates are released from the surface in the form of water molecules. However, since the adsoiption of OH is stronger, and the OH ions move faster to the surface of the electrode, they are deactivated, increasing potential. There will be a competition on the electrode between the adsorption of OH and NH3.

[00045] The results of the mechanism are summarized by the proposed reactions given below, as well as Figure A6.

Pt₅, f OH^" <s> Pt_n, -OH~_tsdj { ] }

2P^ + 2NH, <=> 2Pt₁₁, - NH₁₁^ (2)

Ff,, - NH,_(Λ|. * Pt₅, ™ OH ^•<*, <=> Pt, - NH_{?( ltS}, + Pt,₀ -I- H,0 ₊ ef (3) *» - NH _J(a« + Pι« " OH \m <a Pi₁, - NH _>d! + Pi₁₁ * H,O 4 c^" _{f4j R1S)} 1% - NH ^ ₊ Pt₁₁, - OH-W) <* Pt_h( - N_{( ld}, 4 Pt_{111 +} H₁O ^ e ^" ₍₅₎

2Pl ₁₀ - H^ c* Pi₁₁ - N₁^ ₊ Pt_{10 (ό)}

Pt_JΛ - N_?^ «* Pr_1& + N_2iϊϊ

(7)

[00046] This mechanism can be extended to the electro-oxidation of other chemicals in alkaline solution at low potentials (negative vs. standard hydrogen electrode (SHE)). For example, the mechanism has been extended to the electro-oxidation of ethanol. The proposed mechanism clearly defines the expectations for the design of better electrodes: the materials used should enhance the adsorption of NH3 and/or ethanol, or other chemicals of interest. The proposed mechanism can also enhance the electrolysis of water in alkaline medium. Through a combination of at least two materials, one material more likely to be adsorbed by OH than the other, active sites are left available for the electro-oxidation of the interested chemicals, such as NH₃ and/or ethanol.

[00047] Significant current densities can be obtained from the oxidation of ammonia on active metals, but such electrodes are far less reversible than those of the present electrochemical cell. Similar cases occur with the electro-oxidation of ethanol in alkaline medium. Furthermore, the activation of the electrodes is limited by surface coverage. The present electrochemical cell overcomes the problems of reversibility as well as deactivation.

[00048] The present electrochemical cell includes a first electrode formed from a layered electrocatalyst.

[00049] The layered electrocatalyst includes at least one active metal layer deposited on a carbon support. In an embodiment, the layered electrocatalyst can further include at least one second metal layer deposited on the carbon support. The carbon support can be integrated with a conductive metal, such as titanium, tungsten, nickel, stainless steel, or other similar conductive metals.

[00050] It is contemplated that the conductive metal integrated with the carbon support can have an inability or reduced ability to bind with metal plating layers used to form the layered electrocatalyst.

[00051] The active metal layer is contemplated to have a strong affinity for the oxidation of ammonia, ethanol, or combinations thereof. The second metal layer is contemplated to have a strong affinity for hydroxide. The affinities of the layers enhance the electronic conductivity of the carbon support.

[00052] In a contemplated embodiment, the second metal layer can be a second layer of an active metal, such that the layered electrocatalyst includes two active metal layers deposited on the carbon support.

[00053] The carbon support can include carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, carbon sheets, carbon nanotubes, carbon nanofibers, or combinations thereof. For example, groups of carbon nanofibers bound in clusters of 6,000, wound on titanium, nickel, carbon steel, or other similar metals, could be used as a carbon support.

[00054] Carbon fibers can include woven or non-woven carbon fibers, that are polymeric or other types of fibers. For example, a bundle of polyacrylonitrile carbon fibers could be used as a carbon support. Solid or hollow nano-sized carbon fibers, having a diameter less than 200 nanometers, can also be useable. Bundles of 6000 or more carbon fibers are contemplated, having an overall diameter up to or exceeding 7 micrometers.

[00055] Carbon microspheres can include nano-sized Buckyball supports, such as free standing spheres of carbon atoms having plating on the inside or outside, having a diameter less than 200 nanometers. Crushed and/or graded microspheres created from the grinding or milling of carbon, such as Vulcan 52, are also useable. [00056] Carbon sheets can include carbon paper, such as that made by Toray™, having a thickness of 200 nanometers or less. Useable carbon sheets can be continuous, perforated, or partially perforated. The perforations can have diameters ranging from 1 to 50 nanometers.

[00057] Carbon tubes can include any type of carbon tube, such as nano-CAPP or nano- CPT, carbon tubes made by Pyrograf®, or other similar carbon tubes. For example, carbon tubes having a diameter ranging from 100 to 200 nanometers and a length ranging from 3,000 to 100,000 nanometers could be used.

[00058] The metal layers can be deposited on the carbon support through sputtering, electroplating, such as through use of a hydrochloric acid bath, vacuum electrodeposition, other similar methods, or combinations thereof.

[00059] The active metal layer can include rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

[00060] The second metal layer can include platinum, iridium, or combinations thereof. The ratio of platinum to iridium can range from 99.99:0.01 to 50:50. In an embodiment, the ratio of platinum can range from 95:5 to 70:30. In other embodiments, the ratio of platinum to iridium can range from 80:20 to 75:25.

[00061] Each layer can be deposited on the carbon support in a thickness ranging from 10 nanometers to 10 microns. For example, a loading of at least 2 mg/cm for each layer can be provided to a carbon fiber support, while both layers can provide a total loading ranging from 4 mg/cm to 10 mg/cm.

[00062] Each layer can wholly or partially cover the carbon support. Each layer can be perforated. Each layer can have regions of varying thickness.

[00063] It is contemplated that the thickness and coverage of each layer can be varied to accommodate the oxidation of a specified feedstock. For example, a feedstock having a IM concentration of ammonia could be oxidized by an electrode having a layer that is 0.5 microns in thickness at a rate of 100 mA/cm^Λ2.

[00064] The present electrochemical cell can thereby be customized to meet the needs of users. For example, a first user may need to generate hydrogen for fuel from the rapid oxidation of ethanol, while a second user may need to remove ammonia from a fixed volume of water for purification purposes.

[00065] The strong activity of ammonia and/or ethanol of the electrocatalyst used in the present electrochemical cell, even with low ammonia concentrations, is useful in processes for removing ammonia from contaminated effluents. Accordingly, the electrocatalysts described herein can be used to oxidize the ammonia contamination in the contaminated effluent. An electrolytic cell may be prepared which uses at least one electrode comprising the layered electrocatalyst described herein to oxidize ammonia contaminants in effluents. The effluent may be fed as a continuous stream, wherein the ammonia is electrochemically removed from the effluent, and the purified effluent is released or stored for other uses.

[00066] The present electrochemical cell also includes a second electrode that includes a conductor. The second electrode can include carbon, platinum, rhenium, palladium, nickel, Raney Nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, other similar conductors, or combinations thereof.

[00067] Figure A7 shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating (and also during the operation of the electrode). The fibers were wrapped on a titanium gauze, and were therefore in electric contact with the metal at different points. This improvement allowed easy and homogenous plating of the fibers at any point. The electronic conductivity at any point in the fiber was the same as the electronic conductivity of the Ti gauze.

[00068] Figure A8 shows a Scanning Electron Microscope photograph of the electrode before plating and after plating. A first layer of Rh was deposited on the electrode to increase the electronic conductivity of the fibers and to serve as a free substrate for the adsorption of OH. (OH has more affinity for Rh than for Pt). A second layer consisting of Pt was plated on the electrode. The Pt layer did not cover all the Rh sites, leaving the Rh surface to act as a preferred OH adsorbent.

[00069] Figure A9 shows the cyclic voltammetry performance for the electro-oxidation of ammonia on different electrode compositions. Notice that the carbon fibers plated with only Rh are not active for the reaction, while when they are plated with only Pt, the electrode is active but it is victim of poisoning. On the other hand, when the electrode is made by plating in layers: first Rh is deposited and then a second layer consisting of Pt is deposited, the electrode keeps the activity. This is explained by the mechanism presented previously. Figure A9 demonstrates that the proposed method or preparation of the electrode eliminates surface blockage difficulties.

[00070] Figure AlO shows the effect of different total loading on the electro-oxidation of ammonia. The results indicate that the catalyst with the lowest loading is more efficient for the electro-oxidation of ammonia. This feature results in a more economical process owing to a lower expense related to the catalyst. Additional loading of the catalyst just causes the formation of layers over layers that do not take part in the reaction.

[00071] Figure Al l illustrates the effect of the catalyst composition of the electro-oxidation of ammonia in alkaline solution. There is not a notable difference in the performance of the electrode due to the composition of the electrode. This lack of difference is due to the fact that as long as a first layer of Rh is plated on the electrode, surface blockage will be avoided. Additional plating of Pt would cause the growth of a Pt island (see SEM picture, Figure A8), which is not completely active in the whole surface.

[00072] Figure Al 2 shows the effect of ammonia concentration on the performance of the electrode. The effect of ammonia concentration is negligible on the electrode performance. This is due to the fact that the active Pt sites have already adsorbed the

NFB needed for a continuous reaction. Due to this feature, the present electrochemical cell is operable using only trace amounts of ammonia and/or ethanol.

[00073] Figure A13 depicts the effect of the concentration of OH on the electro-oxidation of ammonia. A larger concentration of OH causes a faster rate of reaction. The electrode maintains continuous activity, without poisoning, independent of the OH concentration.

[00074] Figure A14 shows the evaluation of the electrode for the electro-oxidation of ethanol. Continuous electro-oxidation of ethanol in alkaline medium is achieved without surface blockage. The present electrochemical cell is thereby useable to oxidize ethanol, as well as ammonia. The present electrochemical cell can further oxidize combinations of ammonia and ethanol independently or simultaneously.

[00075] In an embodiment, the second electrode and first electrode can both include a layered electrocatalyst. [00076] The second electrode is contemplated to have an activity toward the evolution of hydrogen in alkaline media.

[00077] The first electrode, second electrode, or combinations thereof, can include rotating disc electrodes, rotating ring electrodes, cylinder electrodes, spinning electrodes, ultrasound vibration electrodes, other similar types of electrodes, or combinations thereof.

[00078] The electrochemical cell further includes a basic electrolyte disposed in contact with each of the electrodes. The basic electrolyte can include any alkaline electrolyte that is compatible with the layered electrocatalyist, does not react with ammonia or ethanol, and has a high conductivity.

[00079] The basic electrolyte can include any hydroxide donor, such as inorganic hydroxides, alkaline metal hydroxides, or alkaline earth metal hydroxides. In an embodiment the basic electrolyte can include potassium hydroxide, sodium hydroxide, or combinations thereof.

[00080] The basic electrolyte can have a concentration ranging from 0.1 M to 7M. In an embodiment, the basic electrolyte can have a concentration ranging from 3M to 7M. It is contemplated that the basic electrolyte can be present in a volume and/or concentration that exceeds the stoichiometric proportions of the oxidation reaction, such as two to five times greater than the concentration of ammonia, ethanol, or combinations thereof. In an embodiment, the basic electrolyte can have a concentration three times greater than the amount of ammonia and/or ethanol.

[00081] The electrochemical cell can include ammonia, ethanol, or combinations thereof, which can be supplied as a fuel/feedstock for oxidation to produce hydrogen.

[00082] The present electrochemical cell can advantageously oxidize any combination of ammonia or ethanol, independently or simultaneously. A feedstock containing either ammonia, ethanol, or both ammonia and ethanol could be thereby be oxidized using the present electrochemical cell. Additionally, separate feedstocks containing ammonia and ethanol could be individually or simultaneously oxidized using the electrochemical cell.

[00083] The ammonia, ethanol, or combinations thereof can be present in extremely small quantities, millimolar concentrations, and/or ppm concentrations, while still enabling the present electrochemical cell to be useable.

[00084] The ammonia and/or ethanol can be aqueous, having water, the basic electrolyte, or another liquid as a carrier. For example, ammonium hydroxide can be stored until ready for use, then fed directly into the electrochemical cell.

[00085] It is also contemplated that ammonia can be stored as liquefied gas, at a high pressure, then combined with water and the basic electrolyte when ready for use. Ammonia could also be obtained from ammonium salts, such as ammonium sulfate, dissolved in the basic electrolyte.

[00086] In an embodiment, the ammonia, ethanol, or combinations thereof can have a concentration ranging from 0.01 M to 5M. In other embodiments, the concentration of ammonia, ethanol, or combinations thereof, can range from IM to 2M. At higher temperatures, a greater concentration of ammonia can be used.

[00087] The properties of the present electrochemical cell, such as the thickness of the plating of the first electrode, can be varied to accommodate the concentration of the feedstock.

[00088] The ability of the present electrochemical cell to perform oxidation of extremely small quantities, millimolar concentrations, and/or ppm concentrations of ammonia and/or ethanol enables the electrochemical cell to advantageously be used as a detector/sensor for ammonia and/or ethanol.

[00089] The ability of the present electrochemical cell to perform oxidation of both extremely small and large concentrations of ammonia and/or ethanol enables the electrochemical cell to advantageously accommodate a large variety of feedstocks.

[00090] The oxidation of ammonia and/or ethanol by the present electrochemical cell is endothermic. As a result, the electrochemical cell can be used to cool other adjacent or attached devices and equipment, such as a charging battery. Additionally, the heat from the adjacent devices and/or equipment can facilitate the efficiency of the reaction of the electrochemical cell, creating a beneficial, synergistic effect.

[00091] Electrical current is supplied to the electrochemical cell, in communication with the first electrode. The electrical current can be alternating current, direct current, or combinations thereof. The amount of electrical current applied to the first electrode can vary depending on the properties of the cell and/or feedstock, based on the Faraday equation.

[00092] Contemplated current densities can range from 25 mA/cm^Λ2 to 500 mA/cm^Λ2. In other embodiments, the current densities can range from 50 mA/cm^Λ2 to 100 mA/cm^Λ2. In still other embodiments, the current densities can range from 25 mA/cm^Λ2 to 50 mA/cm^Λ2. Current densities can also range from 50 mA/cm^Λ2 to 500 mA/cm^Λ2, from 100 mA/cm^Λ2 to 400 mA/cm^Λ2, or from 200 mA/cm^Λ2 to 300 mA/cm^Λ2.

[00093] The electrical current can be provided from a power generation system, specifically designed to oxidize ammonia and/or ethanol. The power generation system is contemplated to be adjustable to large current, while providing power of one volt or less. Power sources can also include solar panels, alternate or direct current sources, wind power sources, fuel cells, batteries, other similar power sources, or combinations thereof.

[00094] When electrical current is supplied to the present electrochemical cell, it is contemplated that the electrochemical cell can produce hydrogen, nitrogen, carbon dioxide, or combinations thereof. A controlled ammonia feedstock reacts, in the alkaline medium, in combination with the controlled voltage and current, to produce nitrogen and hydrogen. A controlled ethanol feedstock reacts similarly, to produce carbon dioxide and hydrogen.

[00095] The present electrochemical cell is contemplated to be operable at temperatures ranging from -50 degrees Centigrade to 200 degrees Centigrade. In an embodiment, the cell can be operable from 20 degrees Centigrade to 70 degrees

Centigrade. In another embodiment, the cell is operable from 60 degrees

Centigrade to 70 degrees Centigrade.

[00096] The cell can also be operable from 20 degrees Centigrade to 60 degrees Centigrade, from 30 degrees Centigrade to 70 degrees Centigrade, from 30 degrees Centigrade to 60 degrees Centigrade, or from 40 degrees Centigrade to 50 degrees Centigrade. [00097] It is contemplated that in an embodiment, a higher pressure can be used, enabling the present electrochemical cell to be operable at higher temperatures.

[00098] The present electrochemical cell is contemplated to be useable at pressures ranging from less than 1 atm to 10 atm.

[00099] In an embodiment, the present electrochemical cell can include a hydrophilic membrane. The hydrophilic membrane can include polypropylene, Teflon™ or other polyamides, other hydrophilic polymers, or combinations thereof. It is contemplated that the hydrophilic membrane can selectively permit the exchange of hydroxide.

[000100] In another embodiment, the present electrochemical cell can include a separator. The separator can include polypropylene, glassy carbon, other similar materials, or combinations thereof.

[000101] A prototype electrochemical cell for the continuous electrolysis of ammonia and/or ethanol in alkaline medium produced H2 continuously, with a faradic efficiency of 100%. The design of the cell was small (4x4 cm), and permitted a significant production of H₂ at a small energy and power consumption. A cloud of H₂ was observed when generated at the cathode of the cell. The production of H₂ was massive, which demonstrates the use of the cell for in-situ H₂ production.

[000102] Figure A15 shows the energy balance and the power balance on the ammonia electrochemical cell. The electrochemical cell outperforms a commercial water electrolyzer. Both the energy and the power balance of the cell indicate that the cell could operate by utilizing some energy produced by a PEM H₂ fuel cell, and the system (ammonia electrolytic cell/PEM fuel cell) will still provide some net energy. This arrangement can be used to minimize hydrogen storage.

[000103] In one exemplary system, an excess of 480 kg of H₂ was produced per day. A total capital investment of $1,000,000 is needed for the construction of the power system. A comparison of the economic analysis for the production of H₂ using the ammonia continuous electrolytic cell with current state of the art technologies (natural gas reforming and water electrolysis) for distributed power has been performed. The continuous ammonia electrolyzer can produce hydrogen at less than $2 per Kg.

Compared to other technologies for in situ hydrogen production, savings are substantial — using numbers provided by the National Academy of Science, the continuous ammonia electrolyzer produced H2 about 20% cheaper than H2 can be produced using natural gas steam reforming, and about 57% cheaper than using water electrolysis.

[000104] The present electrochemical cell can be made using the following method:

[000105] A first electrode can be formed by combining at least one active metal layer with a carbon support, as described previously. In an embodiment, at least one second metal layer can also be combined with the carbon support. The combining of the layers with the carbon support can be performed using electrodeposition.

[000106] The schematic for the construction of the electrode is shown if Figure A7. The plating procedure can include two steps: 1. First layer plating and 2. Second layer plating.

[000107] First layer plating includes plating the carbon support with materials that show a strong affinity for OH. Examples include, but are not limited to Rh, Ru, Ni, and Pd. In one preferred embodiment, Rh is used. The first layer coverage should completely plate the carbon support. In some embodiments, the first layer coverage is at least 2 mg/cm of carbon fiber to guarantee a complete plating of the carbon support. In other embodiments, the first layer coverage can be 2.5 mg/cm, 3.0 mg/cm, 3.5 mg/cm, or more.

[000108] Second layer plating includes plating the electrode with materials that have a strong affinity for the oxidation of ammonia and/or ethanol. Examples include: Pt and Ir. Monometallic deposition and/or bimetallic deposition of these materials can be performed. Ratios of PtIr can range from 100% Pt-0% Ir to 50% Pt-50% Ir.

[000109] Table AI summarizes the plating conditions for the anode and the cathode of the electrochemical cell. After plating the Rhodium, the electrode is weighted. The weight corresponds to the Rhodium loading. Then, the Platinum is deposited on top of the

Rhodium. After the procedure is completed, the electrode is measured again. The measurement will correspond to the total loading. The Platinum loading is obtained by subtracting the total loading from the previous Rhodium measurement. The relation of Platinum to Rhodium is then calculated as the percentage of fixed loading. Because the loading depends on the length of the fiber, another measurement should be calculated.

It is known that 10 cm of fiber weights 39.1 mg, and because the weight of the fiber is known, then by proportionality, it can be known the length of the total fiber that is being used in each electrode.

[000110] Table All summarizes the general conditions of a plating bath useable to create the electrodes. During the entire plating procedure, the solution was mixed to enhance the transport of the species to the carbon support.

[000111] Table AIII shows examples of some electrode compositions, lengths, and loadings of active metals.

Table AI Conditions for Electro-plating Technique in the Deposition of Different Metals on the Carbon Fibers and/or Carbon Nanotubes

Table All General Conditions of the Plating Bath

[000112] A second electrode is also provided. The second electrode is contemplated to include a conductor, such a carbon support plated with nickel. In an embodiment, the second electrode can be formed in a similar manner and have similar materials as the first electrode.

[000113] The current fibers can rest on a metal gauze, such as by wrapping the fibers on the gauze. Any inter material for the acidic deposition bath, if used, as well as the basic electrolyte, could be used. In an embodiment, the metal gauze can be titanium, however other conductors are also contemplated, such as nickel, stainless steel, or tungsten.

[000114] The first and second electrodes are then secured in a housing, such that a space exists between the two electrodes. The housing can include at least one inlet, for receiving ammonia, ethanol, water, basic electrolyte, or combinations thereof. The housing can be made from any nonconductive polymer, such as polypropylene, Teflon™ or other polyamides, acrylic, or other similar polymers.

[000115] The housing can further include at least two outlets. A first outlet is contemplated to receive gas produced at the cathode, and a second outlet is contemplated to receive gas produced at the anode. A third outlet could be used to remove liquid from the electrochemical cell.

[000116] A basic electrolyte and a fuel are then provided to the housing. The basic electrolyte, fuel, or combinations thereof, can be provided to the housing through one or more inlets, independently or simultaneously. The basic electrolyte and the fuel could be provided using the same inlet, or through different inlets. [000117] In an embodiment, the electrochemical cell can be provided with the basic electrolyte and/or the fuel without use of inlets, such as by providing a fixed supply of electrolyte and/or fuel to the housing prior to sealing the housing.

[000118] The housing is then sealed, which can include using gaskets, such as gaskets made from Teflon™ or other polyamides, a sealant, a second housing, or other similar methods. The sealed housing can have any volume, depending on the quantity of fuel and/or electrolyte contained within. The sealed housing can have any shape or geometry, as needed, to facilitate stacking, storage, and/or placement of the housing within a facility.

[000119] A power source is then connected to the first and second electrodes, and current is provided from the power source. The power source can include one or more solar panels, alternate or direct current sources, wind power sources, fuel cells, batteries, other similar power sources, or combinations thereof.

[000120] The power source can be connected directly to the electrodes, or, in an embodiment, to a power input of the housing.

[000121] In a contemplated embodiment, a voltage controller can be provided to the housing to limit the voltage from the power source to no more than one volt.

[000122] In an embodiment, the method for making the electrochemical cell can include placing a separator or a membrane between the first electrode and the second electrode. It is contemplated that the membrane or separator must remain wet after contacting the solution within the cell to prevent shrinkage, retain orientation of the polymer, and retain the chemical properties of the membrane or separator.

[000123] The separator or membrane can include polypropylene, Teflon™ or other polyamides, and/or fuel cell grade asbestos.

[000124] It is contemplated that the first electrode, the second electrode, or combinations thereof, could be deposited on the separator or membrane, such as by spraying or plating, such that no separate electrodes are required in addition to the separator or membrane.

[000125] In an embodiment, the method for making the electrochemical cell can include providing one or more flow controllers to the housing. The flow controllers can be useable to distribute fuel within the cell, and to remove gas bubbles from the surface of the electrodes, for increasing the surface area of the electrodes able to be contacted.

[000126] In a contemplated embodiment, one or more sensors can be placed in one or more of the outlets for detecting ammonia, ethanol, or combinations thereof. It is also contemplated that one or more of the present electrochemical cells could be usable as sensors for detecting ammonia and/or ethanol. The electrochemical cell can be deactivated if sufficient concentrations of ammonia, ethanol, or combinations thereof are detected in the outlets, for preventing contamination of neighboring cells and/or equipment, and for preventing exposure to human operators.

[000127] It is further contemplated that the present electrochemical cell can be constructed such that the housing can itself function as the second electrode.

[000128] In this embodiment, a first electrode is formed, as described previously, and is secured within a housing formed from the second electrode, such as a housing formed at least partially from nickel.

[000129] The present electrochemical cell can be used to form one or more electrochemical cell stacks by connecting a plurality of electrochemical cells in series, parallel, or combinations thereof.

[000130] The electrochemical cell stack can include one or more bipolar plates disposed between at least two adjacent electrochemical cells. The bipolar plate can include an anode electrode, a cathode electrode, or combinations thereof. For example, the bipolar plate could function as an anode for both adjacent cells, or the bipolar plate could have anode electrode materials deposited on a first side and cathode electrode materials deposited on a second side.

[000131] The electrochemical cell stack can have any geometry, as needed, to facilitate stacking, storage, and/or placement. Cylindrical, prismatic, spiral, tubular, and other similar geometries are contemplated.

[000132] In an embodiment, a single cathode electrode can be used as a cathode for multiple electrochemical cells within the stack, each cell having an anode electrode. [000133] In this embodiment, at least a first electrochemical cell would include a first electrode having a layered electrocatalyst, as described previously, and a second electrode having a conductor.

[000134] At least a second of the electrochemical cells would then have a third electrode that includes the layered electrocatalyst. The second electrode would function as the cathode for both the first and the second electrochemical cells.

[000135] In a contemplated embodiment, an electrochemical cell stack having a plurality of anode electrodes having the layered electrocatalyst and a single cathode having a conductor can be used. For example, multiple disc-shaped anode electrodes can be placed in a stacked configuration, having single cathode electrode protruding through a central hole in each anode electrode.

[000136] A basic electrolyte and ammonia, ethanol, or combinations thereof can then be placed in contact with each of the plurality of anode electrodes and with the cathode electrode.

[000137] It is contemplated that this embodiment of the electrochemical cell stack can include a hydrogen-permeable membrane for facilitating collection of the hydrogen produced by the electrochemical cell stack.

[000138] The described embodiment of the electrochemical cell stack can further have a fuel and current inlet in communication with each of the plurality of anodes, simultaneously, such as by extending through the central hole of each of the anodes.

[000139] Referring now to Figure Al, Figure Al depicts a diagram of the components of the present electrochemical cell (10).

[000140] The electrochemical cell (10) is depicted having a first electrode (11), which functions as an anode. The first electrode (11) is shown having a layered electrocatalyst (12) deposited on a carbon support (26). The layered electrocatalyst (12) is contemplated to include at least one active metal layer and can include at least one second metal layer.

[000141] The electrochemical cell (10) further depicts a second electrode (13) that functions as a cathode, which is contemplated to include a conductor. [000142] The electrodes (11, 13) are disposed within a housing (5), such that a space exists between the electrodes (11, 13).

[000143] The electrochemical cell (10) is shown containing a basic electrolyte (36), such as sodium hydroxide or potassium hydroxide. The electrochemical cell (10) is also shown containing ammonia (20) and ethanol (22) within the basic electrolyte (36).

It is contemplated that the electrochemical cell (10) is useable for the continuous oxidation of ammonia or ethanol individually, or simultaneously.

[000144] Electrical current (34) from a power generation system (7) in communication with the electrodes (11, 13) is applied to the first electrode (11) to cause the production of hydrogen (32) through the oxidation of the ammonia (20) and/or ethanol (22).

[000145] The depicted electrochemical cell (10) is shown having a hydrophilic membrane (9) disposed between the electrodes (11, 13), which is contemplated to selectively permit hydroxide exchange.

[000146] Referring now to Figure A2, a diagram of an embodiment of an electrochemical cell stack (16) is shown. The electrochemical cell stack (16) is shown having two of electrochemical cells, separated by a bipolar plate (3), which are depicted in greater detail in Figure Al .

[000147] The electrochemical cell stack (16) includes a first anode (1 Ia) adjacent a first end plate (92a). A first gasket (94a) and a second gasket (94b) are disposed between the first anode (1 Ia) and the bipolar plate (3).

[000148] The electrochemical cell stack (16) also includes a second anode (l ib) adjacent a second endplate (92b), opposite the first end plate (92a). A third gasket (94c) and a fourth gasket (94d) are disposed between the second anode (1 Ib) and the bipolar plate (3).

[000149] The bipolar plate includes a cathode (13) disposed thereon. The cathode (13) is contemplated to function as a cathode for both the first anode (1 Ia) and the second anode (1 Ib).

[000150] While Figure A2 depicts the electrochemical cell stack (16) including two electrochemical cells, it should be understood that any number of electrochemical cells, such as five cells or nine cells, can be stacked in a similar fashion, to produce a desired volume of hydrogen.

[000151] Referring now to Figure Al 6, a diagram of an embodiment of a method for making the present electrochemical cell is shown.

[000152] Figure Al 6 depicts that a first electrode is formed by combining one or more active metal layers and, optionally, a second metal layer with a carbon support, such as by electrodeposition. (100). A second electrode having a conductor is provided (102).

[000153] The first and second electrodes are secured in a housing having at least one inlet and at least two outlets (104), with a space existing between the electrodes.

[000154] A basic electrolyte is provided to the housing (106). A fuel is also provided to the housing (108). The housing is then sealed (110), such as by using gaskets, a sealant, a second housing, or through other similar means.

[000155] A power source is then connected to the electrodes, and current is supplied (112).

[000156] B

FIELD

[000157] The present embodiments relate to a fuel cell for the production of electrical energy utilizing ammonia, ethanol, or combinations thereof.

BACKGROUND

[000158] A need exists for a fuel cell able to oxidize ammonia, ethanol, or combinations thereof in alkaline media continuously.

[000159] A further need exists for a fuel cell that utilizes an anode having a unique layered electrocatalyst that overcomes the positioning of the electrode due to surface blockage and enables operation of the fuel cell at low temperatures.

[000160] A need also exists for a fuel cell that utilizes a layered electrocatalyst with a carbon support that provides a hard rate of performance for the carbon support.

[000161] The present embodiments meet these needs. BRIEF DESCRIPTION OF THE DRAWINGS

[000162] The detailed description will be better understood in conjunction with the accompanying drawings as follows:

[000163] Figure Bl depicts an embodiment of the present fuel cell.

[000164] Figure B2 depicts an embodiment of an electric device assemblage powered by a fuel cell stack.

[000165] Figure B3 shows adsorption of OH on a Platinum cluster.

[000166] Figure B4 shows experimental results of the electro-oxidation of ammonia on a Pt electrode, using a rotating disk electrode.

[000167] Figure B5 shows results of microscopic modeling of the electro-adsorption of OH, indicating that if the sites were available, the adsorption of OH would continue producing higher oxidation currents

[000168] Figure B6 shows a representation of the electro-oxidation mechanism of ammonia on a Pt electrode. As NH3 reaches the Pt surface it competes with the OH" electro- adsorption. Since the Electro-adsorption of OH" is faster on Pt the active sites of the electrode get saturated with the OH adsorbates causing deactivation of the electrode.

[000169] Figure B7 shows shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating and operation.

[000170] Figure B8 shows SEM photographs of the carbon fibers before plating and after plating.

[000171] Figure B9 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the performance of the carbon fiber electrodes with different compositions.

[000172] Figure BlO shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the loading of the electrode, with low loading 5 mg of total metal/cm of carbon fiber and high loading 10 mg of metal/cm of carbon fiber.

[000173] Figure BIl shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing differing electrode compositions at low loading of 5 mg of total metal/cm of fiber. Electrode compositions include High Rh, Low Pt (80% Rh, 20% Pt), and low Rh and high Pt (20% Rh, 80% Pt).

[000174] Figure B12 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, with differing ammonia concentration, indicating that the concentration of NH3 does not affect the kinetics of the electrode.

[000175] Figure B13 shows cyclic voltammetry performance of Effect of solution at 25°C, with differing OH concentration, indicating that a higher the concentration of OH causes faster kinetics.

[000176] Figure B14 shows cyclic voltammetry performance of IM ethanol and IM KOH solution at 25°C, indicating that the present electrochemical cell is also useable for the continuous oxidation of ethanol.

[000177] The present embodiments are detailed below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[000178] Before explaining the present apparatus in detail, it is to be understood that the apparatus is not limited to the particular embodiments and that it can be practiced or carried out in various ways.

[000179] The present embodiments relate to a fuel cell that utilizes ammonia, ethanol, or combinations thereof for producing electrical current.

[000180] Conventional hydrogen production is expensive, energy inefficient, and creates unwanted byproducts. Further, current sources and processes for hydrogen production require high operating temperatures and complicated processes, and often produce gas having impurities.

[000181] The present fuel cell provides the benefit of continuous power generation based on renewable alternative fuels, such as ammonia, ethanol, or combinations thereof, that can operate at low temperatures, and/or low pressure, through use of a layered electrocatalyst as an anode.

[000182] Hydrogen is the main fuel source for power generation using fuel cells, but the effective storage and transportation of hydrogen presents technical challenges. Current hydrogen production costs cause fuel cell technology for distributed power generation to be economically non-competitive when compared to traditional oil-fueled power systems. Current distributed hydrogen technologies are able to produce hydrogen at costs of $5 to $6 per kg of H2. This high production cost is due in part to high product separation/purification costs and high operating temperatures and pressures required for hydrogen production.

[000183] Using current technologies, hydrogen can be obtained by the partial oxidation, catalytic steam reforming, or thermal reforming of alcohols and hydrocarbons. However, all of these processes take place at high temperatures and generate a large amount of COχ as byproducts, which must be removed from the hydrogen product. Most of these COχ byproducts cause degeneration of fuel cell performance due to poisoning of the fuel cell catalysts. The removal of these byproducts from the fuel stream is complicated, bulky, and expensive.

[000184] Currently, the cleanest way to obtain pure hydrogen is by the electrolysis of water. During the electrolysis of water electrical power (usually provided by solar cells) is used to break the water molecule, producing both pure oxygen and hydrogen. The disadvantage of this process is that a large amount of electrical power is needed to produce hydrogen. The theoretical energy consumption for the oxidation of water is 66 W-h per mole of H^Λ produced (at 25 ⁰C). Therefore, if solar energy is used (at a cost of $0.2138/kWh), the theoretical cost of hydrogen produced by the electrolysis of water is estimated to be $7 per kg of H2.

[000185] The present fuel cell overcomes the costs and difficulties associated with the production of hydrogen, by enabling continuous, controllable production of electric current using plentiful and inexpensive feedstocks that include ammonia and/or ethanol.

[000186] Plating of carbon fibers, nano-tubes, and other carbon supports is a difficult task that is problematic due to the relatively low electronic conductivity of these materials. The low conductivity of carbon supports can cause a poor coating of the surface of the support, which can be easily removed. The electronic conductivity of carbon fibers and other carbon supports decreases along the length from the electrical connection. Therefore, the furthest point of contact to the electric connection transfers a low current when compared with the closest point to the electric contact.

[000187] The present fuel cell advantageously utilizes a unique layered electrocatalyist that provides electrodes with uniform current distribution, enhanced adherence and durability of coating, and overcomes surface coverage affects, leaving a clean active surface area for reaction. The layered electrocatalyst further enables the fuel cell to operate at lower temperatures than conventional fuel cells.

[000188] It was believed that the surface blockage caused during the ammonia electrolysis in alkaline medium was due to the presence of elemental Nitrogen, according to the mechanism proposed by Gerisher:

\ *-? " i

2( MNH, + OH^" <z^±MNH + H,O ÷e^" l ^ds⁾

- I U NB -f M NH +zt→ M ,N,H , )

2 \ ^ " ^" \/

2 \ - * '^■ k> - i

Deactivati 00 Reac-1io« : 2 { IVTN H + OH^" £==5? MN i iiO ÷ e^" )

where M represents an active site on the electrode.

[000189] The present fuel cell incorporates the demonstrations of two independent methods indicating that the proposed mechanism by Gerisher is not correct, and that OH needs to be adsorbed on the electrode for the reactions to take place. Furthermore, the electrode is deactivated by the OH adsorbed at the active sites.

[000190] Results from molecular modeling indicate that the adsorption of OH on an active Pt site is strong (chemisorption) and can be represented by the following reaction:

Pt_]C + OH^~ ^ Pt_w - OΪT_w + e ^' [000191] Figure B3 shows the bond between the OH and the platinum cluster. The system was modeled using Density functional Methods. The computations were performed using the B3PW91 and LANL2DZ method and basis set, respectively. The binding energy for the Pt-OH cluster is high with a value of- 133.24 Kcal/mol, which confirms the chemisorption of OH on a Pt cluster active site.

[000192] Additionally, results from microscopic modeling as well as experimental results on a rotating disk electrode (RDE) indicate that the adsorption of OH is strong and responsible for the deactivation of the catalyst.

[000193] Figure B4 compares the baseline of a KOH solution with the same solution in the presence of OH. The curves indicate that the first oxidation peaks that appear at about -

0.7 V vs Hg/HgO electrode had to do with the electro-adsorption of OH.

[000194] Figure B5 shows a comparison of the predicted results (by microscopic modeling) with the experimental results for the electro-adsorption of OH. The results indicate that the model predict the experimental results fairly well. Furthermore, an expression for the surface blockage due to the adsorption of OH at the surface of the electrode was developed (notice that the active sites for reaction theta decay with the applied potential due to adsorbates). If the surface were clean (see results Model without coverage), the electro-adsorption of OH would continue even at higher potentials and faster.

[000195] Compiling the experimental results with the modeling results the following mechanism for the electro-oxidation of ammonia in alkaline medium is proposed: First the adsorption of OH takes place. As the ammonia molecule approaches the electrode, it is also adsorbed on the surface. Through the oxidation of ammonia, some

OH adsorbates are released from the surface in the form of water molecule.

However, since the adsoiption of OH is stronger and the OH ions move faster to the surface of the electrode, they are deactivated increasing potential. There will be a competition on the electrode between the adsorption of OH and NH3.

[000196] The results of the mechanism are summarized on the proposed reactions given below, as well as Figure B6. Pt_ΪU + OH^" <=> Pt:₀ - OH~_laa, (1)

2Pt₁, + 2NH₁ O 2Pt₁₀ - NH₁^ (2)

Pt_t0 - NH_JM} -i Ft₅₆ - OH^*^ « Pt₅, - NH ,,^ + Pt_J<? + ΪLCM- G^" (3> Ft_{i a} - NlI₃^, + Pl₁, - OHV) <=> PL,* - NH^₁ + Ni₃ * H₂O+ c^" _(4> ^₈) PI₁₆ - ^"NH,^ + Pt_lβ - OH- ,,4) c* Pt₁, - N,_w, f Pi₁, + H .O - e^" _{f5 )}

2Pt_Λ ~ N^ c=* Pi₁, - N,_(l-) +- Pl_{111 (}6)

[000197] This mechanism can be extended to the electro-oxidation of other chemicals in alkaline solution at low potentials (negative vs. SHE). For example, it has been extended to the electro-oxidation of ethanol. The proposed mechanism clearly defines the expectations for the design of better electrodes: the materials used should enhance the adsorption of

NH3 and/or ethanol, or other chemicals of interest. The proposed mechanism can also enhance the electrolysis of water in alkaline medium. It is necessary a combination of at least two materials: One of the materials should be more likely to be adsorbed by OH than the other; this will leave active sites available for the electro-oxidation of the interested chemicals, such as NH3 and/or ethanol.

[000198] The present fuel cell includes a housing, which can be made from any nonconductive material, including polypropylene, Teflon or other polyamides, acrylic, or other similar polymers. The housing can have any shape, size, or geometry, depending on the volume of liquid to be contained in the fuel cell, and any considerations relating to stacking, storage, and/or placement in a facility.

[000199] The housing can include any number of inlets and/or outlets. Outlets can receive gasses produced at the anode and/or cathode and can be used to remove liquid from the fuel cell. Inlets can be used to provide basic electrolyte, ammonia and/or ethanol, oxidant, or combinations thereof, simultaneously or separately.

[000200] The housing can be sealed, such as by using one or more gaskets, including gaskets made from Teflon or other polyamides, a sealant, a second housing, or combinations thereof. [000201] An anode is disposed within the housing. The anode includes a layered electrocatalyst, which includes at least one active metal layer and at least one second metal layer deposited on a carbon support. The carbon support can be integrated with a conductive metal, such as titanium, tungsten, nickel, stainless steel, or other similar conductive metals.

[000202] It is contemplated that the conductive metal integrated with the carbon support can have an inability or reduced ability to bind with metal plating layers used to form the layered electrocatalyst.

[000203] The active metal layer is contemplated to have a strong affinity for the oxidation of ammonia, ethanol, or combinations thereof. The second metal layer is contemplated to have a strong affinity for hydroxide. The affinities of the layers enhance the electronic conductivity of the carbon support, and facilitate the operation of the fuel cell at low temperatures.

[000204] In a contemplated embodiment, the second metal layer can be a second layer of an active metal, such that the layered electrocatalyst includes two active metal layers deposited on the carbon support.

[000205] The carbon support can include carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, carbon sheets, carbon nanofibers, carbon nanotubes, or combinations thereof. For example, groups of carbon nanofibers bound in clusters of 6,000, wound on titanium, nickel, carbon steel, or other similar metals, could be used as a carbon support.

[000206] Carbon fibers can include woven or non-woven carbon fibers, that are polymeric or other types of fibers. For example, a bundle of polyacrylonitrile carbon fibers could be used as a carbon support. Solid or hollow nano-sized carbon fibers, having a diameter less than 200 nanometers, can also be useable. Bundles of 6000 or more carbon fibers are contemplated, having an overall diameter up to or exceeding 7 micrometers.

[000207] Carbon microspheres can include nano-sized Buckyball supports, such as free standing spheres of carbon atoms having plating on the inside or outside, having a diameter less than 200 nanometers. Crushed and/or graded microspheres created from the grinding or milling of carbon, such as Vulcan 52, are also useable.

[000208] Carbon sheets can include carbon paper, such as that made by Toray™, having a thickness of 200 nanometers or less. Useable carbon sheets can be continuous, perforated, or partially perforated. The perforations can have diameters ranging from 1 to 50 nanometers.

[000209] Carbon tubes can include any type of carbon tube, such as nano-CAPP or nano- CPT, carbon tubes made by Pyrograf®, or other similar carbon tubes. For example, carbon tubes having a diameter ranging from 100 to 200 nanometers and a length ranging from 3,000 to 100,000 nanometers could be used.

[000210] The metal layers can be deposited on the carbon support through sputtering, electroplating, such as through use of a hydrochloric acid bath, vacuum electrodeposition, other similar methods, or combinations thereof.

[000211] The active metal layer can include rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

[000212] The second metal layer can include platinum, iridium, or combinations thereof. The ratio of platinum to iridium can range from 99.99:0.01 to 50:50. In an embodiment, the ratio of platinum can range from 95:5 to 70:30. In other embodiments, the ratio of platinum to iridium can range from 80:20 to 75:25.

[000213] Each layer can be deposited on the carbon support in a thickness ranging from 10 nanometers to 10 microns. For example, a loading of at least 2 mg/cm for each layer can be provided to a carbon fiber support, while both layers can provide a total loading ranging from 4 mg/cm to 10 mg/cm.

[000214] Each layer can wholly or partially cover the carbon support. Each layer can be perforated. Each layer can have regions of varying thickness.

[000215] It is contemplated that the thickness and coverage of each layer can be varied to accommodate the use a specified ammonia or ethanol feedstock. The present fuel cell can thereby be customized to meet the needs of users.

[000216] A basic electrolyte is disposed within the housing in contact with the anode. The basic electrolyte can include any alkaline electrolyte that is compatible with the layered electrocatalyist, does not react with ammonia or ethanol, and has a high conductivity. [000217] The basic electrolyte can include any hydroxide donor, such as inorganic hydroxides, alkaline metal hydroxides, or alkaline earth metal hydroxides. In an embodiment the basic electrolyte can include potassium hydroxide, sodium hydroxide, or combinations thereof.

[000218] The basic electrolyte can have a concentration ranging from 0.1 M to 7M. In an embodiment, the basic electrolyte can have a concentration ranging from 3M to 7M. It is contemplated that the basic electrolyte can be present in a volume and/or concentration that exceeds the stoichiometric proportions of the oxidation reaction, such as two to five times greater than the concentration of ammonia, ethanol, or combinations thereof. In an embodiment, the basic electrolyte can have a concentration three times greater than the amount of ammonia and/or ethanol.

[000219] The fuel cell can also include ammonia, ethanol, or combinations thereof, disposed within the housing in communication with the anode.

[000220] The present fuel cell can advantageously utilize any combination of ammonia or ethanol, independently or simultaneously. A feedstock containing either ammonia, ethanol, or both ammonia and ethanol could be thereby be utilized by the present fuel cell. Additionally, separate feedstocks containing ammonia and ethanol could be individually or simultaneously utilized using the fuel cell.

[000221] The ammonia, ethanol, or combinations thereof can be present in extremely small quantities, millimolar concentrations, and/or ppm concentrations, while still enabling the present fuel cell to be useable.

[000222] The ammonia and/or ethanol can be aqueous, having water, the basic electrolyte, or another liquid as a carrier. For example, ammonium hydroxide can be stored until ready for use, then fed directly into the fuel cell.

[000223] It is also contemplated that ammonia can be stored as liquefied gas, at a high pressure, then combined with water and the basic electrolyte when ready for use. Ammonia could also be obtained from ammonium salts, such as ammonium sulfate, dissolved in the basic electrolyte.

[000224] In an embodiment, the ammonia, ethanol, or combinations thereof can have a concentration ranging from 0.01 M to 5M. In other embodiments, the concentration of ammonia, ethanol, or combinations thereof, can range from IM to 2M. At higher temperatures, a greater concentration of ammonia can be used. The properties of the present fuel cell, such as the thickness of the plating of the anode, can be varied to accommodate the concentration of the feedstock.

[000225] The ability of the present fuel cell to utilize both extremely small and large concentrations of ammonia and/or ethanol enables the fuel cell to advantageously accommodate a large variety of feedstocks.

[000226] The reaction performed by the present fuel cell is exothermic. As a result, the fuel cell can be used to heat other adjacent or attached devices and equipment, such as adjacent electrochemical cells performing endothermic reactions, creating a beneficial, synergistic effect.

[000227] The present fuel cell also includes a cathode, which includes a conductor, disposed within the housing in contact with the basic electrolyte. The cathode can include carbon, platinum, rhenium, palladium, nickel, Raney Nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, other similar conductors, or combinations thereof.

[000228] It is further contemplated that the present fuel cell can be constructed such that the housing can itself function as the cathode. For example, the housing could be formed at least partially from nickel.

[000229] Figure B7 shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating (and also during the operation of the electrode). The fibers were wrapped on a titanium gauze, and were therefore in electric contact with the metal at different points. This improvement allowed an easy and homogenous plating of the fibers at any point. The electronic conductivity at any point in the fiber was the same as the electronic conductivity of the

Ti gauze.

[000230] Figure B8 shows a Scanning Electron Microscope photograph of the electrode before plating and after plating. A first layer of Rh was deposited on the electrode to increase the electronic conductivity of the fibers and to serve as a free substrate for the adsorption of OH. (OH has more affinity for Rh than for Pt). A second layer consisting of Pt was plated on the electrode. The Pt layer did not cover all the Rh sites, leaving the Rh surface to act as a preferred OH adsorbent.

[000231] Figure B9 shows the cyclic voltammetry performance for the electro-oxidation of ammonia on different electrode compositions. Notice that the carbon fibers plated with only Rh are not active for the reaction, while when they are plated with only Pt, the electrode is active but it is victim of poisoning. On the other hand, when the electrode is made by plating in layers: first Rh is deposited and then a second layer consisting of Pt is deposited, the electrode keeps the activity. This is explained by the mechanism presented previously. Figure B9 demonstrates that the proposed method or preparation of the electrode eliminates surface blockage difficulties.

[000232] Figure BlO shows the effect of different total loading on the electro-oxidation of ammonia. The results indicate that the catalyst with the lowest loading is more efficient for the electro-oxidation of ammonia. This feature results in a more economical process owing to a lower expense related to the catalyst. Additional loading of the catalyst just causes the formation of layers over layers that do not take part in the reaction.

[000233] Figure BI l illustrates the effect of the catalyst composition of the electro-oxidation of ammonia in alkaline solution. There is not a notable difference in the performance of the electrode due to the composition of the electrode. This lack of difference is due to the fact that as long as a first layer of Rh is plated on the electrode, surface blockage will be avoided. Additional plating of Pt would cause the growth of a Pt island (see

SEM picture, Figure B8), which is not completely active in the whole surface.

[000234] Figure B 12 shows the effect of ammonia concentration on the performance of the electrode. The effect of ammonia concentration is negligible on the electrode performance. This is due to the fact that the active Pt sites have already adsorbed the NFB needed for a continuous reaction. Due to this feature, the present fuel cell is operable using only trace amounts of ammonia and/or ethanol.

[000235] Figure B 13 depicts the effect of the concentration of OH on the electro-oxidation of ammonia. A larger concentration of OH causes a faster rate of reaction. The electrode maintains continuous activity, without poisoning, independent of the OH concentration.

[000236] Figure B 14 shows the evaluation of the electrode for the electro-oxidation of ethanol. Continuous electro-oxidation of ethanol in alkaline medium is achieved without surface blockage. The present fuel cell is thereby able to use ethanol, as well as ammonia. The present fuel cell can further utilize combinations of ammonia and ethanol independently or simultaneously.

[000237] In an embodiment, the second electrode and first electrode can both include a layered electrocatalyst.

[000238] The schematic for the construction of the electrode is shown in Figure B7. The plating procedure includes two steps: 1. First layer plating and 2. Second layer plating.

[000239] First layer plating includes plating the carbon support with materials that show a strong affinity for OH. Examples include, but are not limited to Rh, Ru, Ni, and Pd. In one preferred embodiment, Rh is used. The first layer coverage should completely plate the fiber. In some embodiments, the first layer coverage is at least 2 mg/cm of fiber to guarantee a complete plating of the fiber. In other embodiments, the first layer coverage can be 2.5 mg/cm, 3.0 mg/cm, 3.5 mg/cm, or more.

[000240] Second layer plating includes plating the electrode with materials that have a strong affinity for the oxidation of ammonia and/or ethanol. Examples include: Pt and Ir. Monometallic deposition and/or bimetallic deposition of these materials can be performed. Ratios of PtIr can range from 100% Pt-0% Ir to 50% Pt-50% Ir.

[000241] Table BI summarizes the plating conditions for the anode and the cathode of the fuel cell. After plating the Rhodium, the electrode is weighted. The weight corresponds to the Rhodium loading. Then, the Platinum is deposited on top of the Rhodium. After the procedure is completed, the electrode is measured again. The measurement will correspond to the total loading. The Platinum loading is obtained by subtracting the total loading from the previous Rhodium measurement. The relation of Platinum to

Rhodium is then calculated as the percentage of fixed loading. Because the loading depends on the length of the fiber, another measurement should be calculated. It is known that 10 cm of fiber weights 39.1 mg, and because the weight of the fiber is known, then by proportionality, it can be known the length of the total fiber that is being used in each electrode .

[000242] Table BII summarizes the general conditions of a plating bath useable to create the electrodes. During the entire plating procedure, the solution was mixed to enhance the transport of the species to the carbon support.

[000243] Table Bill shows examples of some electrode compositions, lengths, and loadings of active metals.

Table BI Conditions for Electro-plating Technique in the Deposition of Different Metals on the Carbon Fibers and/or Carbon Nanotubes

Table BII General Conditions of the Plating Bath

Table Bill Examples of some Electrode Compositions and Loadings

[000244] The first electrode, second electrode, or combinations thereof, can include rotating disc electrodes, rotating ring electrodes, cylinder electrodes, spinning electrodes, ultrasound vibration electrodes, other similar types of electrodes, or combinations thereof.

[000245] An oxidant is disposed within the housing in communication with the cathode, for connecting with a power conditioner, a load, or combinations thereof. The oxidant can include oxygen, air, other oxidizers, or combinations thereof. Pure oxygen is a superior oxidizer, however other oxidizers, including air, can be used to avoid the expense of pure oxygen.

[000246] The oxidant used can have a pressure ranging from less than 1 atm to 10 atm.

[000247] The power conditioner, load, or combinations thereof, which is in communication with the anode, causes the oxidation of the ammonia, ethanol, or combinations thereof. This oxidation causes the fuel cell to form a current.

[000248] The amount of electrical current produced can vary depending on the properties of the cell and/or feedstock, based on the Faraday equation.

[000249] The present fuel cell is contemplated to be operable at temperatures ranging from

-50 degrees Centigrade to 200 degrees Centigrade. In an embodiment, the fuel cell can be operable from 20 degrees Centigrade to 70 degrees Centigrade. In another embodiment, the cell is operable from 60 degrees Centigrade to 70 degrees Centigrade.

[000250] The fuel cell can also be operable from 20 degrees Centigrade to 60 degrees Centigrade, from 30 degrees Centigrade to 70 degrees Centigrade, from 30 degrees Centigrade to 60 degrees Centigrade, or from 40 degrees Centigrade to 50 degrees Centigrade.

[000251] It is contemplated that in an embodiment, a higher pressure can be used, enabling the present fuel cell to be operable at higher temperatures.

[000252] The present fuel cell is contemplated to be useable at pressures ranging from less than 1 atm to 10 atm. [000253] In an embodiment, the present fuel cell can include an ionic exchange membrane or separator disposed between the anode and the cathode. The ionic exchange membrane or separator can include polypropylene, Teflon or other polyamides, other polymers, glassy carbon, fuel-cell grade asbestos, or combinations thereof. It is contemplated that the ionic exchange membrane or separator can selectively permit the exchange of hydroxide.

[000254] It is contemplated that the membrane or separator must remain wet after contacting the solution within the cell to prevent shrinkage, retain orientation of the polymer, and retain the chemical properties of the membrane or separator.

[000255] It is further contemplated that the first electrode, the second electrode, or combinations thereof, could be deposited on the separator or membrane, such as by spraying or plating, such that no separate electrodes are required in addition to the separator or membrane.

[000256] In an embodiment, the fuel cell can include one or more flow controllers within the housing. The flow controllers can be useable to distribute electrolyte, ammonia, ethanol, and/or oxidant within the cell, and to remove gas bubbles from the surface of the electrodes, increasing the surface area of the electrodes able to be contacted.

[000257] The present fuel cell can be used to form one or more fuel cell stacks by connecting a plurality of fuel cells in series, parallel, or combinations thereof.

[000258] The fuel cell stack can include one or more bipolar plates disposed between at least two adjacent fuel cells. The bipolar plate can include an anode electrode, a cathode electrode, or combinations thereof. For example, the bipolar plate could function as an anode for both adjacent cells, or the bipolar plate could have anode electrode materials deposited on a first side and cathode electrode materials deposited on a second side.

[000259] The fuel cell stack can have any geometry, as needed, to facilitate stacking, storage, and/or placement. Cylindrical, prismatic, spiral, tubular, and other similar geometries are contemplated.

[000260] In an embodiment, a single cathode electrode can be used as a cathode for multiple fuel cells within the stack, each cell having an anode electrode. [000261] In this embodiment, at least a first fuel cell would include a first anode having a layered electrocatalyst, as described previously, and a cathode having a conductor.

[000262] At least a second of the fuel cells would then have a second anode that includes the layered electrocatalyst. The cathode of the first fuel cell would function as the cathode for both the first and the second fuel cells.

[000263] In a contemplated embodiment, a fuel cell stack having a plurality of anode electrodes having the layered electrocatalyist and a single cathode having a conductor can be used. For example, multiple disc-shaped anode electrodes can be placed in a stacked configuration, having single cathode electrode protruding through a central hole in each anode electrode.

[000264] A basic electrolyte and ammonia, ethanol, or combinations thereof can then be placed in contact with each of the plurality of anode electrodes and with the cathode electrode.

[000265] The described embodiment of the fuel cell stack can further have an inlet in communication with each of the plurality of anodes, simultaneously, such as by extending through the central hole of each of the anodes.

[000266] The present embodiments also relate to a hydrogen fuel cell and electrochemical cell stack which include a plurality of hydrogen fuel cells and a plurality of electrochemical cells. Each of the plurality of hydrogen fuel cells and each of the plurality of electrochemical cells are contemplated to include anodes having a layered electrocatalyst, as described previously.

[000267] The fuel cells and electrochemical cells can also include cathodes having a conductor, a basic electrolyte, and ammonia, ethanol, or combinations thereof.

[000268] It is contemplated that the plurality of hydrogen fuel cells are powered by the hydrogen produced by the plurality of electrochemical cells. The plurality of electrochemical cells are powered by the current produced by the fuel cells, enabling the electrochemical cells to produce hydrogen, using continuously supplied ammonia and/or ethanol feedstock.

[000269] Through use of the embodied hydrogen fuel cell and electrochemical cell stack, it is contemplated that a net power gain is obtained, such that the current produced by the fuel cells is in excess of the power required to fuel the electrochemical cells.

[000270] The present embodiments also relate to an electric consuming device assemblage that includes one or more electric consuming devices, such as motors.

[000271] The assemblage further includes one or more hydrogen fuel cells, as described previously, and one or more electrochemical cells, as described previously. The electrochemical cells produce hydrogen for powering the hydrogen fuel cells using ammonia and/or ethanol feedstock, while the hydrogen fuel cells produce current sufficient to power both the electrochemical cells and the electric consuming devices.

[000272] Controllers can be used to regulate the voltage applied to the electrochemical cells. A controller can also be used to regulate the pressure of the electrochemical cells, the fuel cells, or combinations thereof.

[000273] It is also contemplated that controllers can be used to regulate the temperature of the cells, the pH of the cells, the flow of ammonia and/or ethanol, and/or the heat flux of the cells.

[000274] Controllers are also useable to regulate the flow of gas out of the electrochemical cells and/or the load applied to the electrochemical cells.

[000275] Referring now to Figure Bl, Figure Bl depicts a diagram of the components of the present fuel cell (14).

[000276] The fuel cell (14) is depicted having a housing (39), which can be made from any nonconductive materials and have any size or shape necessary to accommodate the contents of the fuel cell (14).

[000277] An anode (40) is disposed within the housing (39). The anode is shown having a layered electrocatalyst (12) deposited on a carbon support (26). The layered electrocatalyst (12) is contemplated to include at least one active metal layer and at least one second metal layer. The layered electrocatalyst (12) is contemplated to enable the fuel cell (14) to be operable at low temperatures.

[000278] The fuel cell (14) further includes a basic electrolyte (36), such as sodium hydroxide or potassium hydroxide having a concentration ranging from 0.1M to 7M, disposed within the housing (39) adjacent the anode (40).

[000279] Figure Bl further depicts the fuel cell (14) having a cathode (42) disposed within the housing (39) adjacent the basic electrolyte (36). The cathode (42) is contemplated to include a conductor.

[000280] The fuel cell (14) is also shown containing ammonia (20) and ethanol (22) within the basic electrolyte (36). It is contemplated that the fuel cell (14) can continuously utilize ammonia or ethanol individually, or simultaneously.

[000281] An oxidant (48), which can include air, oxygen, or combinations thereof, is disposed within the housing (39) in communication with the cathode (42), for connecting with a power conditioner (41), a load, or combinations thereof.

[000282] The power conditioner (41), load, or combinations thereof, is in communication with the anode (40), which oxidizes the ammonia (20), ethanol (22), or combinations thereof, allowing the fuel cell (14) to generate an electric current (34).

[000283] The depicted fuel cell (14) is shown having an ionic exchange membrane (9) disposed between the anode (40) and the cathode (42), which is contemplated to selectively permit hydroxide exchange.

[000284] Referring now to Figure B2, a diagram of an electric consuming device assemblage (44) is shown. The electric consuming device assemblage (44) is shown having an electric consuming device (43), a stack containing a plurality of electrochemical cells (10a, 10b, 10c), and stack containing a plurality of hydrogen fuel cells (14a, 14b, 14c).

[000285] A bipolar plate (3) is shown disposed between two adjacent fuel cells (14a, 14b). The bipolar plate can include one or more electrodes.

[000286] Hydrogen (32) from the electrochemical cells (10a, 10b, 10c) is used to fuel the plurality of hydrogen fuel cells (14a, 14b, 14c). The fuel cells (14a, 14b, 14c) produce electric current (34a, 34b), which is sufficient to power both the electrochemical cells (10a, 10b, 10c) and the electric consuming device (44). [000287] A controller (8) is useable to regulate the voltage and/or current applied to the electrochemical cells (10a, 10b, 10c), and/or the flow of the hydrogen (32). The controller (8) is also useable to control the pressure, temperature, pH, flow of ammonia/ethanol, and/or the heat flux of the electrochemical cells (10a, 10b, 10c) and the fuel cells (14a, 14b, 14c).

[000288] C

FIELD

[000289] The present embodiments relate to an electrochemical method for providing hydrogen using ammonia, ethanol, or combinations thereof.

BACKGROUND

[000290] A need exists for an electrochemical method that incorporates use of an electrochemical cell able to oxidize ammonia, ethanol, or combinations thereof in alkaline media continuously.

[000291] A further need exists for an electrochemical method that utilizes an electrode having a unique layered electrocatalyst that overcomes the positioning of the electrode due to surface blockage.

[000292] A need also exists for an electrochemical method that utilizes a layered electrocatalyst with a carbon support that provides a hard rate of performance for the carbon support.

[000293] The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

[000294] The detailed description will be better understood in conjunction with the accompanying drawings as follows:

[000295] Figure Cl depicts an embodiment of an electrochemical cell useable with the present method.

[000296] Figure C2 depicts an exploded view of an embodiment of the an electrochemical cell stack useable with the present method. [000297] Figure C3 shows adsorption of OH on a Platinum cluster.

[000298] Figure C4 shows experimental results of the electro-oxidation of ammonia on a Pt electrode, using a rotating disk electrode.

[000299] Figure C5 shows results of microscopic modeling of the electro-adsorption of OH, indicating that if the sites were available, the adsorption of OH would continue producing higher oxidation currents

[000300] Figure C6 shows a representation of the electro-oxidation mechanism of ammonia on a Pt electrode. As NH3 reaches the Pt surface it competes with the OH" electro- adsorption. Since the Electro-adsorption of OH" is faster on Pt the active sites of the electrode get saturated with the OH adsorbates causing deactivation of the electrode.

[000301] Figure C7 shows shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating and operation.

[000302] Figure C8 shows SEM photographs of the carbon fibers before plating and after plating.

[000303] Figure C9 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the performance of the carbon fiber electrodes with different compositions.

[000304] Figure ClO shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the loading of the electrode, with low loading 5 mg of total metal/cm of carbon fiber and high loading 10 mg of metal/cm of carbon fiber.

[000305] Figure CIl shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing differing electrode compositions at low loading of 5 mg of total metal/cm of fiber. Electrode compositions include High Rh, Low Pt (80% Rh, 20% Pt), and low Rh and high Pt (20% Rh, 80% Pt).

[000306] Figure C 12 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, with differing ammonia concentration, indicating that the concentration of NH3 does not affect the kinetics of the electrode.

[000307] Figure C13 shows cyclic voltammetry performance of Effect of solution at 25°C, with differing OH concentration, indicating that a higher the concentration of OH causes faster kinetics. [000308] Figure C14 shows cyclic voltammetry performance of IM ethanol and IM KOH solution at 25°C, indicating that the present electrochemical cell is also useable for the continuous oxidation of ethanol.

[000309] Figure C15 shows energy (a) and Power balance (b) of an ammonia electrochemical cell, exhibiting a low energy consumption compared to that of a commercial water electrolyzer.

[000310] Figure C 16 depicts an embodiment of the steps of the present method.

[000311] The present embodiments are detailed below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[000312] Before explaining the present apparatus in detail, it is to be understood that the apparatus is not limited to the particular embodiments and that it can be practiced or carried out in various ways.

[000313] The present embodiments relate to an electrochemical method for providing hydrogen through a reaction from the oxidation of ammonia, ethanol, or combinations thereof.

[000314] Conventional hydrogen production is expensive, energy inefficient, and creates unwanted byproducts.

[000315] The present electrochemical method provides the benefit of continuous, in-situ generation of hydrogen through the oxidation of ammonia, ethanol, or combinations thereof. The present electrochemical method produces hydrogen through the oxidation of both ammonia and ethanol, with a faradic efficiency of 100%. In both cases, the reaction that takes place at the cathode is the reduction of water in alkaline medium, through the following reaction:

[000316] 2f/₂O + 2«r → //, + 2OH^' E" - 0^,S2 V vs SHE

where SHE is a standard hydrogen electrode.

[000317] Hydrogen is the main fuel source for power generation using fuel cells, but the effective storage and transportation of hydrogen presents technical challenges. Current hydrogen production costs cause fuel cell technology for distributed power generation to be economically non-competitive when compared to traditional oil-fueled power systems. Current distributed hydrogen technologies are able to produce hydrogen at costs of $5 to $6 per kg of H2. This high production cost is due in part to high product separation/purification costs and high operating temperatures and pressures required for hydrogen production.

[000318] Using current technologies, hydrogen can be obtained by the partial oxidation, catalytic steam reforming, or thermal reforming of alcohols and hydrocarbons. However, all of these processes take place at high temperatures and generate a large amount of COχ as byproducts, which must be removed from the hydrogen product. Most of these COχ byproducts cause degeneration of fuel cell performance due to poisoning of the fuel cell catalysts. The removal of these byproducts from the fuel stream is complicated, bulky, and expensive.

[000319] Currently, the cleanest way to obtain pure hydrogen is by the electrolysis of water. During the electrolysis of water electrical power (usually provided by solar cells) is used to break the water molecule, producing both pure oxygen and hydrogen. The disadvantage of this process is that a large amount of electrical power is needed to produce hydrogen. The theoretical energy consumption for the oxidation of water is 66 W-h per mole of H^Λ produced (at 25 ⁰C). Therefore, if solar energy is used (at a cost of $0.2138/kWh), the theoretical cost of hydrogen produced by the electrolysis of water is estimated to be $7 per kg of H2.

[000320] The present electrochemical method overcomes the costs and difficulties associated with the production of hydrogen, by enabling continuous, controllable evolution of hydrogen through the oxidation of plentiful and inexpensive feedstocks that include ammonia and/or ethanol.

[000321] Plating of carbon fibers, nano-tubes, and other carbon supports is a difficult task that is problematic due to the relatively low electronic conductivity of these materials. The low conductivity of carbon supports can cause a poor coating of the surface of the support, which can be easily removed. The electronic conductivity of carbon fibers and other carbon supports decreases along the length from the electrical connection. Therefore, the furthest point of contact to the electric connection transfers a low current when compared with the closest point to the electric contact.

[000322] The present electrochemical method advantageously utilizes a unique layered electrocatalyst that provides electrodes with uniform current distribution and enhanced adherence and durability of coating, and overcomes surface coverage affects, leaving a clean active surface area for reaction.

[000323] It was believed that surface blockage caused during ammonia electrolysis in alkaline medium was due to the presence of elemental Nitrogen, according to the mechanism proposed by Gerisher:

a l NH_j + M ^±→ MNH, ks

Deactivation Reaction:

where M represents an active site on the electrode.

[000324] The present electrochemical method incorporates the demonstrations of two independent methods indicating that the proposed mechanism by Gerisher is not correct, and that OH needs to be adsorbed on the electrode for the reactions to take place. Furthermore, the electrode is deactivated by the OH adsorbed at the active sites.

[000325] Results from molecular modeling indicate that the adsorption of OH on an active Pt site is strong (chemisorption) and can be represented by the following reaction:

Pt_Ji5 + OH^' <* Pt_!C - OH_ξB11) + e^" [000326] Figure C3 shows a bond between a OH and a platinum cluster. The system was modeled using Density functional Methods. The computations were performed using the B3PW91 and LANL2DZ method and basis set, respectively. The binding energy for the Pt-OH cluster is high with a value of- 133.24 Kcal/mol, which confirms the chemisorption of OH on a Pt cluster active site.

[000327] Additionally, results from microscopic modeling as well as experimental results on a rotating disk electrode (RDE) indicate that the adsorption of OH is strong and responsible for the deactivation of the catalyst.

[000328] Figure C4 compares the baseline of a KOH solution with the same solution in the presence of OH. The curves indicate that the first oxidation peaks that appear at about -

0.7 V vs Hg/HgO electrode had to do with the electro-adsorption of OH.

[000329] Figure C5 shows a comparison of the predicted results (by microscopic modeling) with the experimental results for the electro-adsorption of OH. The results indicate that the model predicts the experimental results fairly well. Furthermore, an expression for the surface blockage due to the adsorption of OH at the surface of the electrode was developed (notice that the active sites for reaction theta decay with the applied potential due to adsorbates). If the surface were clean (see results model without coverage), the electro-adsorption of OH would continue even at higher potentials, and would occur more rapidly.

[000330] Compiling the experimental results with the modeling results, the following mechanism for the electro-oxidation of ammonia in alkaline medium is proposed: First the adsorption of OH takes place. As the ammonia molecule approaches the electrode, it is also adsorbed on the surface. Through the oxidation of ammonia, some OH adsorbates are released from the surface in the form of water molecules. However, since the adsoiption of OH is stronger, and the OH ions move faster to the surface of the electrode, they are deactivated, increasing potential. There will be a competition on the electrode between the adsorption of OH and NH3.

[000331] The results of the mechanism are summarized on the proposed reactions given below, as well as Figure C6. Pt_ΪU + OH^" <=> Pt:₀ - OH~_laa, (1)

2Pt₁, + 2NH₁ O 2Pt₁₀ - NH₁^ (2)

2Pt_Λ ~ N^ c=* Pi₁, - N,_(l-) +- Pl_{111 (}6)

[000332] This mechanism can be extended to the electro-oxidation of other chemicals in alkaline solution at low potentials (negative vs. standard hydrogen electrode (SHE)). For example, the mechanism has been extended to the electro-oxidation of ethanol. The proposed mechanism clearly defines the expectations for the design of better electrodes: the materials used should enhance the adsorption of NH3 and/or ethanol, or other chemicals of interest. The proposed mechanism can also enhance the electrolysis of water in alkaline medium. Through a combination of at least two materials, one material more likely to be adsorbed by OH than the other, active sites are left available for the electro-oxidation of the interested chemicals, such as NH3 and/or ethanol.

[000333] Significant current densities can be obtained from the oxidation of ammonia on active metals, but such electrodes are far less reversible than those used by the present electrochemical method. Similar cases occur with the electro-oxidation of ethanol in alkaline medium. Furthermore, the activation of the electrodes is limited by surface coverage. The present electrochemical method overcomes the problems of reversibility as well as deactivation.

[000334] The present electrochemical method includes the step of forming an anode that includes a layered elecrocatalyst.

[000335] The layered electrocatalyst includes at least one active metal layer deposited on a carbon support. The carbon support can be integrated with a conductive metal, such as titanium, tungsten, nickel, stainless steel, or other similar conductive metals.

[000336] It is contemplated that the conductive metal integrated with the carbon support can have an inability or reduced ability to bind with metal plating layers used to form the layered electrocatalyst.

[000337] Active metal layers can include rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

[000338] The active metal layer is contemplated to have a strong affinity for the oxidation of ammonia, ethanol, or combinations thereof. The second metal layer is contemplated to have a strong affinity for hydroxide. The affinities of the layers enhance the electronic conductivity of the carbon support.

[000339] Carbon supports can include carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, carbon sheets, carbon nanotubes, carbon nanofibers, or combinations thereof. For example, groups of carbon nanofibers bound in clusters of 6,000, wound on titanium, nickel, carbon steel, or other similar metals, could be used as a carbon support.

[000340] Carbon fibers can include woven or non-woven carbon fibers, that are polymeric or other types of fibers. For example, a bundle of polyacrylonitrile carbon fibers could be used as a carbon support. Solid or hollow nano-sized carbon fibers, having a diameter less than 200 nanometers, can also be useable. Bundles of 6000 or more carbon fibers are contemplated, having an overall diameter up to or exceeding 7 micrometers.

[000341] Carbon microspheres can include nano-sized Buckyball supports, such as free standing spheres of carbon atoms having plating on the inside or outside, having a diameter less than 200 nanometers. Crushed and/or graded microspheres created from the grinding or milling of carbon, such as Vulcan 52, are also useable.

[000342] Carbon sheets can include carbon paper, such as that made by Toray™, having a thickness of 200 nanometers or less. Useable carbon sheets can be continuous, perforated, or partially perforated. The perforations can have diameters ranging from 1 to 50 nanometers.

[000343] Carbon tubes can include any type of carbon tube, such as nano-CAPP or nano- CPT, carbon tubes made by Pyrograf®, or other similar carbon tubes. For example, carbon tubes having a diameter ranging from 100 to 200 nanometers and a length ranging from 3,000 to 100,000 nanometers could be used.

[000344] In an embodiment, one or more second metal layers can also be deposited on the carbon support. The second metal layers can include additional active metal layers, or layers of different metals.

[000345] The second metal layer can include platinum, iridium, or combinations thereof. The ratio of platinum to iridium can range from 99.99:0.01 to 50:50. In an embodiment, the ratio of platinum can range from 95:5 to 70:30. In other embodiments, the ratio of platinum to iridium can range from 80:20 to 75:25.

[000346] Formation of the anode can include using sputtering, electroplating, such as use of a hydrochloric acid bath, vacuum electrodeposition, or combinations thereof, to deposit metal layers on the carbon support.

[000347] Each layer can be deposited on the carbon support in a thickness ranging from 10 nanometers to 10 microns. For example, a loading of at least 2 mg/cm for each layer can be provided to a carbon fiber support, while both layers can provide a total loading ranging from 4 mg/cm to 10 mg/cm.

[000348] Each layer can wholly or partially cover the carbon support. Each layer can be perforated. Each layer can have regions of varying thickness.

[000349] It is contemplated that the thickness and coverage of each layer can be varied to accommodate the oxidation of a specified feedstock. For example, a feedstock having a IM concentration of ammonia could be oxidized by an electrode having a layer that is 0.5 microns in thickness at a rate of 100 mA/cm^Λ2.

[000350] The strong activity of ammonia and/or ethanol of the electrocatalyst used in the present electrochemical method, even with low ammonia concentrations, is useful in processes for removing ammonia from contaminated effluents. Accordingly, the electrocatalysts described herein can be used to oxidize the ammonia contamination in the contaminated effluent. An electrolytic cell may be prepared which uses at least one electrode comprising the layered electrocatalyst described herein to oxidize ammonia contaminants in effluents. The effluent may be fed as a continuous stream, wherein the ammonia is electrochemically removed from the effluent, and the purified effluent is released or stored for other uses. [000351] A cathode that includes a conductor is also provided. The cathode can include carbon, platinum, rhenium, palladium, nickel, Raney Nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, or combinations thereof.

[000352] A basic electrolyte is disposed between the anode and the cathode. The basic electrolyte can include any alkaline electrolyte that is compatible with the layered electrocatalyst, does not react with ammonia or ethanol, and has a high conductivity.

[000353] The basic electrolyte can include any hydroxide donor, such as inorganic hydroxides, alkaline metal hydroxides, or alkaline earth metal hydroxides. In an embodiment the basic electrolyte can include potassium hydroxide, sodium hydroxide, or combinations thereof.

[000354] The basic electrolyte can have a concentration ranging from 0.1 M to 7M. In an embodiment, the basic electrolyte can have a concentration ranging from 3M to

7M.

[000355] A fuel is disposed within the basic electrolyte. The fuel can include ammonia, ethanol, or combinations thereof. In an embodiment, the ammonia, ethanol, or combinations thereof can have a concentration ranging from 0.01 M to 5M. In other embodiments, the concentration of ammonia, ethanol, or combinations thereof, can range from IM to 2M.

[000356] The present electrochemical method is useable with only trace amounts of ammonia and/or ethanol. Further, the present electrochemical method is useable with ammonia and/or ethanol individually or simultaneously, thereby enabling the present method to accommodate a large variety of feedstocks.

[000357] An electric current is then applied to the anode, such as through use of a power generation system, solar panels, alternate or direct current sources, wind power sources, fuel cells, batteries, other similar power sources, or combinations thereof, causing oxidation of the fuel, forming hydrogen at the cathode. The electric current or current density can be controlled, such as by using controller, to control the output of hydrogen.

[000358] In an embodiment, the present electrochemical method can include regulating the electric current to maintain the voltage of the reaction below one volt. [000359] The present electrochemical method can also include placing a membrane or separator between the anode and cathode. The membrane/separator can be selectively permeable to hydroxide and can include polypropylene, Teflon or other polyamides, fuel-cell grade asbestos, other similar polymers, or combinations thereof.

[000360] The present embodiments also relate to a method for surface buffered, assisted electrolysis of water, which is also useable to produce hydrogen.

[000361] An anode is formed, having a layered electrocatalyst, as described previously. The layered catalyst includes both an active metal layer and at least a second metal layer deposited on a carbon support. A cathode that includes a conductor is also provided.

[000362] An aqueous basic electrolyte, that includes water, is disposed between the anode and the cathode.

[000363] A buffer solution is disposed within the aqueous basic electrolyte. The buffer solution can include ammonia, ethanol, propanol, or combinations thereof. The concentration of the buffer solution can range from 1 ppm to 100 ppm. It is contemplated that only trace amounts of the buffer solution are necessary to assist the electrolysis of the water.

[000364] An electric current is then applied to the anode, causing oxidation of the water within the aqueous basic electrolyte, forming hydrogen at the cathode.

[000365] The electric current can be controlled to regulate the hydrogen output. It is also contemplated that the electric current can be regulated to maintain a voltage of one volt or less.

[000366] The present embodiments further relate to a method for open circuit electrolysis of water.

[000367] An anode is formed, having a layered electrocatalyst, as described previously. The layered catalyst includes both an active metal layer and at least a second metal layer deposited on a carbon support. A cathode that includes a conductor is also provided. [000368] An aqueous basic electrolyte that includes water is disposed between the anode and cathode.

[000369] A buffer solution, which can include trace quantities of ammonia, ethanol, propanol, or combinations thereof, as described previously, is then disposed within the aqueous basic electrolyte.

[000370] The addition of the buffer solution, in the presence of the basic electrolyte and differing metals of the layered electrocatalyst, causes oxidation of the basic electrolyte to produce hydrogen at the cathode, while producing water at the anode.

[000371] The present electrochemical method contemplates use of an electrochemical cell that incorporates the described layered electrocatalyst.

[000372] The electrochemical cell includes a first electrode formed from the layered electrocatalyst.

[000373] The layered electrocatalyst includes at least one active metal layer deposited on a carbon support. In an embodiment, the layered electrocatalyst can further include at least one second metal layer deposited on the carbon support.

[000374] In a contemplated embodiment, the second metal layer can be a second layer of an active metal, such that the layered electrocatalyst includes two active metal layers deposited on the carbon support. The thickness of each metal layer can be varied.

[000375] The present electrochemical cell can thereby be customized to meet the needs of users. For example, a first user may need to generate hydrogen for fuel from the rapid oxidation of ethanol, while a second user may need to remove ammonia from a fixed volume of water for purification purposes.

[000376] Figure C7 shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating (and also during the operation of the electrode). The fibers were wrapped on a titanium gauze, and were therefore, in electric contact with the metal at different points. This improvement allowed an easy and homogenous plating of the fibers at any point. The electronic conductivity at any point in the fiber was the same as the electronic conductivity of the Ti gauze. [000377] The schematic for the construction of the electrode is also shown in Figure C7. The plating procedure can include two steps: 1. First layer plating and 2. Second layer plating.

[000378] First layer plating includes plating the carbon support with materials that show a strong affinity for OH. Examples include, but are not limited to Rh, Ru, Ni, and Pd. In one preferred embodiment, Rh is used. The first layer coverage should completely plate the carbon support. In some embodiments, the first layer coverage is at least 2 mg/cm of carbon fiber to guarantee a complete plating of the carbon support. In other embodiments, the first layer coverage can be 2.5 mg/cm, 3.0 mg/cm, 3.5 mg/cm, or more.

[000379] Second layer plating includes plating the electrode with materials that have a strong affinity for the oxidation of ammonia and/or ethanol. Examples include: Pt and Ir. Monometallic deposition and/or bimetallic deposition of these materials can be performed. Ratios of PtIr can range from 100% Pt-0% Ir to 50% Pt-50% Ir.

[000380] Table CI summarizes the plating conditions for the anode and the cathode of the electrochemical cell. After plating the Rhodium, the electrode is weighted. The weight corresponds to the Rhodium loading. Then, the Platinum is deposited on top of the Rhodium. After the procedure is completed, the electrode is measured again. The measurement will correspond to the total loading. The Platinum loading is obtained by subtracting the total loading from the previous Rhodium measurement. The relation of

Platinum to Rhodium is then calculated as the percentage of fixed loading. Because the loading depends on the length of the fiber, another measurement should be calculated. It is known that 10 cm of fiber weights 39.1 mg, and because the weight of the fiber is known, then by proportionality, it can be known the length of the total fiber that is being used in each electrode.

[000381] Table CII summarizes the general conditions of a plating bath useable to create the electrodes. During the entire plating procedure, the solution was mixed to enhance the transport of the species to the carbon support.

[000382] Table CIII shows examples of some electrode compositions, lengths, and loadings of active metals. Table CI Conditions for Electro-plating Technique in the Deposition of Different Metals on the Carbon Fibers and/or Carbon Nanotubes

Table CII General Conditions of the Plating Bath

Table CIII Examples of some Electrode Compositions and Loadings

[000383] Figure C8 shows a Scanning Electron Microscope photograph of the electrode before plating and after plating. A first layer of Rh was deposited on the electrode to increase the electronic conductivity of the fibers and to serve as a free substrate for the adsorption of OH. (OH has more affinity for Rh than for Pt). A second layer consisting of Pt was plated on the electrode. The Pt layer did not cover all the Rh sites, leaving the Rh surface to act as a preferred OH adsorbent.

[000384] Figure C9 shows the cyclic voltammetry performance for the electro-oxidation of ammonia on different electrode compositions. Notice that the carbon fibers plated with only Rh are not active for the reaction, while when they are plated with only Pt, the electrode is active but it is victim of poisoning. On the other hand, when the electrode is made by plating in layers: first Rh is deposited and then a second layer consisting of Pt is deposited, the electrode keeps the activity. This is explained by the mechanism presented previously. Figure C9 demonstrates that the proposed method or preparation of the electrode eliminates surface blockage difficulties.

[000385] Figure ClO shows the effect of different total loading on the electro-oxidation of ammonia. The results indicate that the catalyst with the lowest loading is more efficient for the electro-oxidation of ammonia. This feature results in a more economical process owing to a lower expense related to the catalyst. Additional loading of the catalyst just causes the formation of layers over layers that do not take part in the reaction.

[000386] Figure CI l illustrates the effect of the catalyst composition of the electro-oxidation of ammonia in alkaline solution. There is not a notable difference in the performance of the electrode due to the composition of the electrode. This lack of difference is due to the fact that as long as a first layer of Rh is plated on the electrode, surface blockage will be avoided. Additional plating of Pt would cause the growth of a Pt island (see SEM picture, Figure C8), which is not completely active in the whole surface.

[000387] Figure C 12 shows the effect of ammonia concentration on the performance of the electrode. The effect of ammonia concentration is negligible on the electrode performance. This is due to the fact that the active Pt sites have already adsorbed the NH3 needed for a continuous reaction. Due to this feature, the present electrochemical cell is operable using only trace amounts of ammonia and/or ethanol.

[000388] Figure C13 depicts the effect of the concentration of OH on the electro-oxidation of ammonia. A larger concentration of OH causes a faster rate of reaction. The electrode maintains continuous activity, without poisoning, independent of the OH concentration.

[000389] Figure C 14 shows the evaluation of the electrode for the electro-oxidation of ethanol. Continuous electro-oxidation of ethanol in alkaline medium is achieved without surface blockage. The present electrochemical cell is thereby useable to oxidize ethanol, as well as ammonia. The present electrochemical cell can further oxidize combinations of ammonia and ethanol independently or simultaneously.

[000390] In an embodiment, the second electrode and first electrode can both include a layered electrocatalyst.

[000391] The second electrode is contemplated to have an activity toward the evolution of hydrogen an alkaline media.

[000392] The first electrode, second electrode, or combinations thereof, can include rotating disc electrodes, rotating ring electrodes, cylinder electrodes, spinning electrodes, ultrasound vibration electrodes, other similar types of electrodes, or combinations thereof.

[000393] The electrochemical cell further includes a basic electrolyte disposed in contact with each of the electrodes.

[000394] It is contemplated that the basic electrolyte can be present in a volume and/or concentration that exceeds the stoichiometric proportions of the oxidation reaction, such as two to five times greater than the concentration of ammonia, ethanol, or combinations thereof. In an embodiment, the basic electrolyte can have a concentration three times greater than the amount of ammonia and/or ethanol.

[000395] The electrochemical cell can include ammonia, ethanol, or combinations thereof, which can be supplied as a fuel/feedstock for oxidation to produce hydrogen.

[000396] The electrochemical cell can advantageously oxidize any combination of ammonia or ethanol, independently or simultaneously. A feedstock containing either ammonia, ethanol, or both ammonia and ethanol could be thereby be oxidized using the present electrochemical cell. Additionally, separate feedstocks containing ammonia and ethanol could be individually or simultaneously oxidized using the electrochemical cell. [000397] The ammonia, ethanol, or combinations thereof can be present in extremely small, millimolar concentrations, while still enabling the electrochemical cell to be useable.

[000398] The ammonia and/or ethanol can be aqueous, having water, the basic electrolyte, or another liquid as a carrier. For example, ammonium hydroxide can be stored until ready for use, then fed directly into the electrochemical cell.

[000399] It is also contemplated that ammonia can be stored as liquefied gas, at a high pressure, then combined with water and the basic electrolyte when ready for use. Ammonia could also be obtained from ammonium salts, such as ammonium sulfate, dissolved in the basic electrolyte.

[000400] In an embodiment, the ammonia, ethanol, or combinations thereof can have a concentration ranging from 0.01 M to 5M. In other embodiments, the concentration of ammonia, ethanol, or combinations thereof, can range from IM to 2M. At higher temperatures, a greater concentration of ammonia can be used.

[000401] The properties of the electrochemical cell, such as the thickness of the plating of the first electrode, can be varied to accommodate the concentration of the feedstock.

[000402] The ability of the electrochemical cell to perform oxidation of extremely small, millimolar concentrations of ammonia and/or ethanol enables the electrochemical cell to advantageously be used as a detector/sensor for ammonia and/or ethanol.

[000403] The ability of the electrochemical cell to perform oxidation of both extremely small and large concentrations of ammonia and/or ethanol enables the electrochemical cell to advantageously accommodate a large variety of feedstocks.

[000404] The oxidation of ammonia and/or ethanol by the electrochemical cell is endothermic. As a result, the electrochemical cell can be used to cool other adjacent or attached devices and equipment, such as a charging battery. Additionally, the heat from the adjacent devices and/or equipment can facilitate the efficiency of the reaction of the electrochemical cell, creating a beneficial, synergistic effect.

[000405] The electrical current supplied to the electrochemical cell can vary depending on the properties of the cell and/or feedstock, based on the Faraday equation.

[000406] Contemplated current densities can range from 25 mA/cm^Λ2 to 500 mA/cm^Λ2. In other embodiments, the current densities can range from 50 mA/cm^Λ2 to 100 mA/cm^Λ2. In still other embodiments, the current densities can range from 25 mA/cm^Λ2 to 50 mA/cm^Λ2. Current densities can also range from 50 mA/cm^Λ2 to

500 mA/cm^Λ2, from 100 mA/cm^Λ2 to 400 mA/cm^Λ2, or from 200 mA/cm^Λ2 to 300 mA/cm^Λ2.

[000407] The electrical current can be provided from a power generation system, specifically designed to oxidize ammonia and/or ethanol. The power generation system is contemplated to be adjustable to large current, while providing power of one volt or less.

[000408] When electrical current is supplied to the electrochemical cell, it is contemplated that the electrochemical cell can produce hydrogen, nitrogen, carbon dioxide, or combinations thereof. A controlled ammonia feedstock reacts, in the alkaline medium, in combination with the controlled voltage and current, to produce nitrogen and hydrogen. A controlled ethanol feedstock reacts similarly, to produce carbon dioxide and hydrogen.

[000409] The electrochemical cell is contemplated to be operable at temperatures ranging from -50 degrees Centigrade to 200 degrees Centigrade. In an embodiment, the cell can be operable from 20 degrees Centigrade to 70 degrees Centigrade. In another embodiment, the cell is operable from 60 degrees Centigrade to 70 degrees Centigrade.

[000410] The cell can also be operable from 20 degrees Centigrade to 60 degrees Centigrade, from 30 degrees Centigrade to 70 degrees Centigrade, from 30 degrees Centigrade to 60 degrees Centigrade, or from 40 degrees Centigrade to 50 degrees Centigrade.

[000411] It is contemplated that in an embodiment, a higher pressure can be used, enabling the electrochemical cell to be operable at higher temperatures.

[000412] The electrochemical cell is contemplated to be useable at pressures ranging from less than 1 atm to 10 atm. [000413] A prototype system for the continuous electrolysis of ammonia and/or ethanol in alkaline medium produced H2 continuously, with a faradic efficiency of 100%. The design of the cell was small (4x4 cm), and permitted a significant production of H₂ at a small energy and power consumption. A cloud of H₂ was observed when generated at the cathode of the cell. The production of H₂ was massive, which demonstrates the use of the cell for in-situ H₂ production.

[000414] Figure C15 shows the energy balance and the power balance on the ammonia electrolytic cell. The electrochemical cell outperforms a commercial water electrolyzer. Both the energy and the power balance of the cell indicate that the cell could operate by utilizing some energy produced by a PEM H₂ fuel cell, and the system

(ammonia electrolytic cell/PEM fuel cell) will still provide some net energy. This arrangement can be used to minimize hydrogen storage.

[000415] In one exemplary system, an excess of 480 kg of H₂ was produced per day. A total capital investment of $1,000,000 is needed for the construction of the power system. A comparison of the economic analysis for the production of H₂ using the ammonia continuous electrolytic cell with current state of the art technologies (natural gas reforming and water electrolysis) for distributed power has been performed. The continuous ammonia electrolyzer can produce hydrogen at less than $2 per Kg. Compared to other technologies for in situ hydrogen production, savings are substantial — using numbers provided by the National Academy of Science, the continuous ammonia electrolyzer produced H2 about 20% cheaper than H2 can be produced using natural gas steam reforming, and about 57% cheaper than using water electrolysis.

[000416] The electrochemical cell can be used to form one or more electrochemical cell stacks, useable with the present electrochemical method, by connecting a plurality of electrochemical cells in series, parallel, or combinations thereof.

[000417] The electrochemical cell stack can include one or more bipolar plates disposed between at least two adjacent electrochemical cells. The bipolar plate can include an anode electrode, a cathode electrode, or combinations thereof. For example, the bipolar plate could function as an anode for both adjacent cells, or the bipolar plate could have anode electrode materials deposited on a first side and cathode electrode materials deposited on a second side. [000418] The electrochemical cell stack can have any geometry, as needed, to facilitate stacking, storage, and/or placement. Cylindrical, prismatic, spiral, tubular, and other similar geometries are contemplated.

[000419] In an embodiment, a single cathode electrode can be used as a cathode for multiple electrochemical cells within the stack, each cell having an anode electrode.

[000420] In this embodiment, at least a first electrochemical cell would include a first electrode having a layered electrocatalyst, as described previously, and a second electrode having a conductor.

[000421] At least a second of the electrochemical cells would then have a third electrode that includes the layered electrocatalyst. The second electrode would function as the cathode for both the first and the second electrochemical cells.

[000422] In a contemplated embodiment, an electrochemical cell stack having a plurality of anode electrodes having the layered electrocatalyst and a single cathode having a conductor can be used. For example, multiple disc-shaped anode electrodes can be placed in a stacked configuration, having single cathode electrode protruding through a central hole in each anode electrode.

[000423] A basic electrolyte and ammonia, ethanol, or combinations thereof can then be placed in contact with each of the plurality of anode electrodes and with the cathode electrode.

[000424] It is contemplated that this embodiment of the electrochemical cell stack can include a hydrogen-permeable membrane for facilitating collection of the hydrogen produced by the electrochemical cell stack.

[000425] The described embodiment of the electrochemical cell stack can further have a fuel and current inlet in communication with each of the plurality of anodes, simultaneously, such as by extending through the central hole of each of the anodes.

[000426] Referring now to Figure Cl, Figure Cl depicts a diagram of the components of an electrochemical cell (10) useable with the present electrochemical method. [000427] The electrochemical cell (10) is depicted having a first electrode (11), which functions as an anode. The first electrode (11) is shown having a layered electrocatalyst (12) deposited on a carbon support (26). The layered electrocatalyst (12) is contemplated to include at least one active metal layer and can include at least one second metal layer.

[000428] The electrochemical cell (10) further depicts a second electrode (13) which is contemplated to include a conductor.

[000429] The electrodes (11, 13) are disposed within a housing (5), such that a space exists between the electrodes (11, 13).

[000430] The electrochemical cell (10) is shown containing a basic electrolyte (36), such as sodium hydroxide or potassium hydroxide. The electrochemical cell (10) is also shown containing ammonia (20) and ethanol (22) within the basic electrolyte (36). It is contemplated that the electrochemical cell (10) is useable for the continuous oxidation of ammonia or ethanol individually, or simultaneously.

[000431] Electrical current (34) from a power generation system (7) in communication with the electrodes (11, 13) is applied to the first electrode (11) to cause the production of hydrogen (32) through the oxidation of the ammonia (20) and/or ethanol (22).

[000432] The depicted electrochemical cell (10) is shown having a hydrophilic membrane (9) disposed between the electrodes (11, 13), which is contemplated to selectively permit hydroxide exchange.

[000433] Referring now to Figure C2, a diagram of an embodiment of an electrochemical cell stack (16) useable with the present method is shown. The electrochemical cell stack (16) is shown having two of electrochemical cells, separated by a bipolar plate (3), which are depicted in greater detail in Figure Cl.

[000434] The electrochemical cell stack (16) includes a first anode (1 Ia) adjacent a first end plate (92a). A first gasket (94a) and a second gasket (94b) are disposed between the first anode (1 Ia) and the bipolar plate (3).

[000435] The electrochemical cell stack (16) also includes a second anode (l ib) adjacent a second endplate (92b) opposite the first end plate (92a). A third gasket (94c) and a fourth gasket (94d) are disposed between the second anode (1 Ib) and the bipolar plate (3).

[000436] The bipolar plate includes a cathode (13) disposed thereon. The cathode (13) is contemplated to function as a cathode for both the first anode (1 Ia) and the second anode (1 Ib).

[000437] While Figure C2 depicts the electrochemical cell stack (16) including two electrochemical cells, it should be understood that any number of electrochemical cells, such as five cells or nine cells, can be stacked in a similar fashion, to produce a desired volume of hydrogen.

[000438] Referring now to Figure C 16, a diagram of an embodiment of the present electrochemical method is shown.

[000439] Figure C 16 depicts that an anode is formed by combining one or more active metal layers and, optionally, a second metal layer, with a carbon support, such as by electrodeposition. (100). A cathode having a conductor is provided (102).

[000440] A basic electrolyte is disposed between the anode and cathode (104). A fuel is also provided within the basic electrolyte ( 106).

[000441] A current is then applied to the anode, such as through connection with a power source, causing oxidation of the fuel, forming hydrogen at the cathode (108).

[000442] D

FIELD

[000443] The present embodiments relate to a layered electrocatalyst useable for the electrochemical oxidation of ammonia, ethanol, or combinations thereof.

BACKGROUND

[000444] A need exists for a layered catalyst able to oxidize ammonia, ethanol, or combinations thereof in alkaline media continuously.

[000445] A further need exists for a layered catalyst that is useable as an electrode in electrochemical cells and fuel cells that overcomes difficulties relating to the positioning of the electrode due to surface blockage. [000446] A need also exists for a layered electrocatalyst that provides a hard rate of performance for a carbon support.

[000447] The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

[000448] The detailed description will be better understood in conjunction with the accompanying drawings as follows:

[000449] Figure Dl depicts a diagram of an embodiment of the present layered electrocatalyst.

[000450] Figure D2 depicts a diagram of an embodiment of a method for making the present layered electrocatalyst.

[000451] Figure D3 shows adsorption of OH on a Platinum cluster.

[000452] Figure D4 shows experimental results of the electro-oxidation of ammonia on a Pt electrode, using a rotating disk electrode.

[000453] Figure D5 shows results of microscopic modeling of the electro-adsorption of OH, indicating that if the sites were available, the adsorption of OH would continue producing higher oxidation currents

[000454] Figure D6 shows a representation of the electro-oxidation mechanism of ammonia on a Pt electrode. As NH3 reaches the Pt surface it competes with the OH" electro- adsorption. Since the Electro-adsorption of OH" is faster on Pt the active sites of the electrode get saturated with the OH adsorbates causing deactivation of the electrode.

[000455] Figure D7 shows shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating and operation.

[000456] Figure D8 shows SEM photographs of the carbon fibers before plating and after plating.

[000457] Figure D9 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the performance of the carbon fiber electrodes with different compositions.

[000458] Figure DlO shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing the loading of the electrode, with low loading 5 mg of total metal/cm of carbon fiber and high loading 10 mg of metal/cm of carbon fiber.

[000459] Figure DI l shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, comparing differing electrode compositions at low loading of 5 mg of total metal/cm of fiber. Electrode compositions include High Rh, Low Pt (80% Rh, 20%

Pt), and low Rh and high Pt (20% Rh, 80% Pt).

[000460] Figure D12 shows cyclic voltammetry performance of IM Ammonia and IM KOH solution at 25°C, with differing ammonia concentration, indicating that the concentration of NH3 does not affect the kinetics of the electrode.

[000461] Figure D13 shows cyclic voltammetry performance of Effect of solution at 25°C, with differing OH concentration, indicating that a higher the concentration of OH causes faster kinetics.

[000462] Figure D14 shows cyclic voltammetry performance of IM ethanol and IM KOH solution at 25°C, indicating that the present electrochemical cell is also useable for the continuous oxidation of ethanol.

[000463] The present embodiments are detailed below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[000464] Before explaining the present apparatus in detail, it is to be understood that the apparatus is not limited to the particular embodiments and that it can be practiced or carried out in various ways.

[000465] The present embodiments relate to a layered electrocatalyst useable for the electrochemical oxidation of ammonia, ethanol, or combinations thereof.

[000466] Conventional hydrogen production is expensive, energy inefficient, and creates unwanted byproducts. The present layered electrocatalyst is useable as an electrode in electrochemical cells for evolving hydrogen through the oxidation of ammonia and/or ethanol.

[000467] The present layered electrocatalyst is further useable as an electrode in alkaline- ammonia and/or ethanol fuel cells for the generation of energy. [000468] Additionally, the present layered electrocatalyst is useable as a sensor for detecting trace quantities of ammonia, ethanol, or combinations thereof, which can include Millimolar quantities, parts per million, or even parts per billion.

[000469] The present layered catalyst is useable to oxidize ammonia, ethanol, or combinations thereof in an alkaline media.

[000470] The present layered catalyst is useable to overcome the costs and difficulties associated with the production of hydrogen when used in an ammonia and/or ethanol electrochemical cell, for use in fuel cells and for other uses, by enabling continuous, controllable evolution of hydrogen through the oxidation of plentiful and inexpensive feedstocks that include ammonia and/or ethanol.

[000471] Plating of carbon fibers, nano-tubes, and other carbon supports is typically difficult, primarily due to the relatively low electronic conductivity of these materials, which can also cause a poor coating of the surface by plating metals. A poor surface coating can be easily removed. The electronic conductivity of the carbon supports decreases along the length of the support from the electrical connection. Therefore, the furthest point of contact to the electric connection transfers a low current when compared to the closest point to the electric contact.

[000472] The present layered electrocatalyst possesses uniform current distribution, exhibits enhanced adherence and durability of coating, and overcomes the surface coverage affects of conventional electrodes, leaving a clean active surface area for a reaction.

[000473] It was believed that the surface blockage caused during ammonia electrolysis in alkaline medium was due to the presence of elemental Nitrogen, according to the mechanism proposed by Gerisher:

? I NH + M τ--^"L-> |yf\^rF \

2 f MNH₃ +OH ^z± MNH _j -i- HjO + e^{" "}

2 ( MNH . + QW ϊi→MNE +110 + c^" ) <^rds) it.

I₁N₂H, + 20H- ± M₂N₂ + 2H_jO + 2e^{^}

^■? i Jt₁

Deacti v ali on React? o u :

/ v \

2| MNB + OH ^{' ™}±=? MN + U _tO ÷ e^" )

where M represents an active site on the electrode.

[000474] The present layered electrocatalyst incorporates the demonstrations of two independent methods indicating that the proposed mechanism by Gerisher is not correct, and that OH needs to be adsorbed on an electrode using the layered electrocatalyst for the reactions to take place. Furthermore, the electrode is deactivated by the OH adsorbed at the active sites.

[000475] Results from molecular modeling indicate that the adsorption of OH on an active Pt site is strong (chemisorption) and can be represented by the following reaction:

Pt_w + OH- <^ Pt_w -QH_{W J} + c-

[000476] Figure D3 shows a bond between OH and a platinum cluster. The system was modeled using Density functional Methods. The computations were performed using the B3PW91 and LANL2DZ method and basis set, respectively. The binding energy for the Pt-OH cluster is high with a value of- 133.24 Kcal/mol, which confirms the chemisorption of OH on a Pt cluster active site. [000477] Additionally, results from microscopic modeling as well as experimental results on a rotating disk electrode (RDE) indicate that the adsorption of OH is strong and responsible for the deactivation of the catalyst.

[000478] Figure D4 compares the baseline of a KOH solution with the same solution in the presence of OH. The curves indicate that the first oxidation peaks that appear at about -

0.7 V vs Hg/HgO electrode had to do with the electro-adsorption of OH.

[000479] Figure D5 shows a comparison of the predicted results (by microscopic modeling) with the experimental results for the electro-adsorption of OH. The results indicate that the model predict the experimental results fairly well. Furthermore, an expression for the surface blockage due to the adsorption of OH at the surface of the electrode was developed (notice that the active sites for reaction theta decay with the applied potential due to adsorbates). If the surface were clean (see results Model without coverage), the electro-adsorption of OH would continue even at higher potentials and faster.

[000480] Compiling the experimental results with the modeling results the following mechanism for the electro-oxidation of ammonia in alkaline medium is proposed: First the adsorption of OH takes place. As the ammonia molecule approaches the electrode, it is also adsorbed on the surface. Through the oxidation of ammonia, some

OH adsorbates are released from the surface in the form of water molecule.

[000481] The results of the mechanism are summarized on the proposed reactions given below, as well as Figure D6.

Pt_ΪU + OH^" <=> Pt:₀ - OH~_laa, (1)

2Pt₁, + 2NH₁ O 2Pt₁₀ - NH₁^ (2)

2Pt_Λ ~ N^ c=* Pi₁, - N,_(l-) +- Pl_{111 (}6)

[000482] This mechanism can be extended to the electro-oxidation of other chemicals in alkaline solution at low potentials (negative vs. standard hydrogen electrode (SHE)). For example, the mechanism has been extended to the electro-oxidation of ethanol. The proposed mechanism clearly defines the expectations for the design of better electrodes using the present layered electrocatalyst: the materials used should enhance the adsorption of NH3 and/or ethanol, or other chemicals of interest. The proposed mechanism can also enhance the electrolysis of water in alkaline medium. The present electrocatalyst combines two materials. One of the materials should be more likely to be adsorbed by OH than the other, which will leave active sites available for the electro- oxidation of the interested chemicals, such as NH3 and/or ethanol.

[000483] The present layered electrocatalyst includes a carbon support integrated with a conductive metal. The carbon support can include carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, nano-sized carbon fibers, nano-sized carbon tubes, carbon sheets, or combinations thereof.

[000484] Carbon fibers can include woven or non-woven carbon fibers, that are polymeric or other types of fibers. For example, a bundle of polyacrylonitrile carbon fibers could be used as a carbon support. Solid or hollow nano-sized carbon fibers, having a diameter less than 200 nanometers, can also be useable. Bundles of 6000 or more carbon fibers are contemplated, having an overall diameter up to or exceeding 7 micrometers.

[000485] Carbon microspheres can include nano-sized Buckyball supports, such as free standing spheres of carbon atoms having plating on the inside or outside, having a diameter less than 200 nanometers. Crushed and/or graded microspheres created from the grinding or milling of carbon, such as Vulcan 52, are also useable.

[000486] Carbon sheets can include carbon paper, such as that made by Toray™, having a thickness of 200 nanometers or less. Useable carbon sheets can be continuous, perforated, or partially perforated. The perforations can have diameters ranging from 1 to 50 nanometers.

[000487] Carbon tubes can include any type of carbon tube, such as nano-CAPP or nano- CPT, carbon tubes made by Pyrograf®, or other similar carbon tubes. For example, carbon tubes having a diameter ranging from 100 to 200 nanometers and a length ranging from 3,000 to 100,000 nanometers could be used.

[000488] The carbon support can be integrated with the conductive metal by wrapping the carbon support around or within the metal, such as by wrapping carbon fibers within titanium gauze. The carbon support could also be bound to a conductive metal, such as by attaching carbon tubes to tungsten using a binder, or attaching a carbon sheet that includes a binder to a plate of titanium.

[000489] Useable conductive metals can include any metallic conductor, such as titanium, nickel, stainless steel, or cobalt. It is contemplated that the conductive metal integrated with the carbon support can have an inability or reduced ability to bind with metal plating layers used to form the present layered electrocatalyst.

[000490] The present layered electrocatalyst includes at least one first metal plating layer deposited, at least partially, on the carbon support. The first metal plating layer is contemplated to be active to hydroxide adsorption, and inactive to a target species, such as ammonia, ethanol, or combinations thereof.

[000491] In an embodiment, the first metal plating layer can include rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

[000492] The first metal plating layer is contemplated to have a thickness ranging from 10 nanometers to 10 microns. For example, the first metal plating layer can have a loading of 2 mg/cm provided to a carbon fiber support.

[000493] One or more second metal plating layers are at least partially deposited on the first metal plating layer. The one or more second metal plating layers are contemplated to be active to the target species. The second metal plating layer can also have a thickness ranging from 10 nanometers to 10 microns. Both metal plating layers can provide a total loading to a carbon fiber support ranging from 4 mg/cm to 10 mg/cm.

[000494] In an embodiment, the second metal plating layer can include platinum, iridium, or combinations thereof. The platinum and iridium can be present in a ratio ranging from 99.99:0.01 to 50:50 platinum to iridium, respectively. For example, the second metal plating layer could have 95:5 platinum to iridium, 70:30 platinum to iridium, 80:20 platinum to iridium, or 75:25 platinum to iridium.

[000495] One or both of the metal plating layers can partially or wholly cover the carbon support. One or both of the metal plating layers can be perforated. Additionally, one or both of the metal layers can have a varying thickness. The first metal plating layer, the second metal plating layer, or combinations thereof, can be a continuous layer.

[000496] For example, the second metal plating layer can have a first thickness ranging from 0 to 500 nanometers on a first portion of the carbon support, and a second thickness ranging from 0 to 500 nanometers on a second portion of the carbon support.

[000497] The resulting layered electrocatalyst is usable as an anode electrode within an electrochemical cell for evolving hydrogen, as an anode electrode within an alkaline ammonia and/or ethanol fuel cell, and as a sensor for detecting trace amounts of ammonia and/or ethanol.

[000498] The present embodiments also relate to a sensor for detecting ammonia, ethanol, or combinations thereof, formed using the present layered catalyst.

[000499] The sensor includes a carbon support integrated with a conductive metal, as described previously.

[000500] At least one active metal plating layer is at least partially deposited on the carbon support. The active metal plating layer can have a thickness ranging from 10 nanometers to 10 microns, and is contemplated to be active to ammonia, ethanol, or combinations thereof. [000501] The active metal plating layer is thereby useable to detect ammonia, ethanol, or combinations thereof at a concentration of 0.01 Millimolar or more.

[000502] In an embodiment, the sensor can include at least one additional metal plating layer at least partially deposited on the carbon support. The additional metal plating layer can have a thickness ranging from 10 nanometers to 10 microns.

[000503] It is contemplated that the additional metal plating layer is active to hydroxide adsoprtion, and inactive to the ammonia, ethanol, or combinations thereof.

[000504] The adsorption of hydroxide by the sensor increases the efficiency of the detection of ammonia and/or ethanol. Use of an additional metal plating layer to adsorb hydroxide further increases the sensitivity of the sensor, lowering the detection limit of the sensor to as little as 1 ppb ammonia and/or ethanol.

[000505] The active metal plating layer of the sensor can include rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof. The additional metal plating layer can include platinum, iridium, or combinations thereof. The carbon support can include comprises carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, nano-sized carbon fibers, nano-sized carbon tubes, carbon sheets, or combinations thereof.

[000506] The sensor operates by producing a potential proportional to the concentration of ammonia, ethanol, or combinations thereof when an electric current is applied to toe sensor.

[000507] The present layered electrocatalyst can be made using the following method:

[000508] A carbon support can be bound with a conductive metal, such that the entirety of the carbon support is in contact with the conductive metal. For example, a sheet of carbon could be adhered to a plate of nickel, or a bundle of carbon fibers could be wrapped around a piece of titanium gauze.

[000509] The present layered electrocatalyst can be created without binding the carbon support to a conductive metal, however use of the conductive metal improves uniform deposition of the plated metal layers on the carbon support. Without binding the carbon support to the conductive metal, uneven distribution plated metal layers can occur, and impurities can develop in the plated metal layers.

[000510] After plating the carbon support to form the layered electrocatalyst, it is contemplated that the conductive metal can be removed. For example, a porous carbon paper could be adhered to a titanium plate during plating, allowing selected plating metals that do not bond with titanium to uniformly coat both sides of the carbon paper. The carbon paper could then be removed from the titanium plate and used as an electrode.

[000511] To plate the carbon support, the bound carbon support is soaked in an electroplating bath having an anode at least twice the size of the bound carbon support while an electrical current is applied to the bound carbon support. In an embodiment, the anode can include a foil formed from platinum, ruthenium, iridium, or alloys thereof.

[000512] It is contemplated that the anode can include, at least in part, the first plating metal that is to be deposited on the bound carbon support.

[000513] The electroplating bath can include an aqueous carrier with an electrolyte and a salt of a first plating metal in the aqueous carrier. The salt of the first plating metal is contemplated to have a mass three to five times the mass of the first plating metal to be deposited on the bound carbon support. The salt of the first plating metal can be a halide salt.

[000514] The electrolyte can be acidic, such as hydrochloric acid or boric acid, or the electrolyte can be basic. In an embodiment, the electrolyte can have a concentration ranging from IM to 5 M.

[000515] The electroplating bath can have a temperature ranging from 25 degrees Centigrade to 80 degrees Centigrade, depending on the selected plating metals, the electric current, and the desired mass of plating metal to be deposited on the bound carbon support.

[000516] The electroplating bath can include a standard hydrogen electrode. The electric current can provide a voltage potential ranging from -0.2 volts to -1.0 volts versus the standard hydrogen electrode.

[000517] The electric current can be controlled to regulate the plating of the layered electrocatalyst. The current can be regulated to maintain constant potential, constant current, staircase current, or pulse current.

[000518] In an embodiment, constant stirring can be provided to the electroplating bath. For example, a magnetic stirrer can be used to provide constant stirring of 60 revolutions per minute, or more.

[000519] In an embodiment, the carbon support can be pretreated to remove at least a portion of a coating on the carbon support, prior to binding the carbon support with the conductive metal. Pretreament can include degreasing the carbon support, such as by using acetone or another solvent.

[000520] The loading of the first plating metal on the carbon support can be measured to determine the mass of the first plating metal that has been deposited.

[000521] In an embodiment, the layered electrocatalyst can be soaked in a second electroplating bath while providing a current, for providing one or more layers of a second plating metal to the electrocatalyst.

[000522] The second electroplating bath can have a second anode at least twice the size of the layered electrocatalyst, and can include a second aqueous carrier with a second electrolyte, and a second salt of a second plating metal. The second salt of the second plating metal has a mass three to five times the mass of the second plating metal to be deposited on the layered electrocatalyst.

[000523] It is contemplated that the thickness and coverage of each plated metal layer can be varied to accommodate the oxidation of a specified feedstock by the layered electrocatalyst. The present layered catalyst can thereby be customized to meet the needs of users.

[000524] Figure D7 shows a schematic representation of the procedure used to increase the electronic conductivity of the carbon fibers during plating (and also during the operation of the electrode). The fibers were wrapped on a titanium gauze, and were therefore in electric contact with the metal at different points. This improvement allowed an easy and homogenous plating of the fibers at any point. The electronic conductivity at any point in the fiber was the same as the electronic conductivity of the Ti gauze. [000525] Figure D8 shows a Scanning Electron Microscope photograph of the electrode before plating and after plating. A first layer of Rh was deposited on the electrode to increase the electronic conductivity of the fibers and to serve as a free substrate for the adsorption of OH. (OH has more affinity for Rh than for Pt). A second layer consisting of Pt was plated on the electrode. The Pt layer did not cover all the Rh sites, leaving the

Rh surface to act as a preferred OH adsorbent.

[000526] Figure D9 shows the cyclic voltammetry performance for the electro-oxidation of ammonia on different electrode compositions. Notice that the carbon fibers plated with only Rh are not active for the reaction, while when they are plated with only Pt, the electrode is active but it is victim of poisoning. On the other hand, when the electrode is made by plating in layers: first Rh is deposited and then a second layer consisting of Pt is deposited, the electrode keeps the activity. This is explained by the mechanism presented previously. Figure D9 demonstrates that the proposed method or preparation of the electrode eliminates surface blockage difficulties.

[000527] Figure DlO shows the effect of different total loading on the electro-oxidation of ammonia. The results indicate that the catalyst with the lowest loading is more efficient for the electro-oxidation of ammonia. This feature results in a more economical process owing to a lower expense related to the catalyst. Additional loading of the catalyst just causes the formation of layers over layers that do not take part in the reaction.

[000528] Figure DI l illustrates the effect of the catalyst composition of the electro-oxidation of ammonia in alkaline solution. There is not a notable difference in the performance of the electrode due to the composition of the electrode. This lack of difference is due to the fact that as long as a first layer of Rh is plated on the electrode, surface blockage will be avoided. Additional plating of Pt would cause the growth of a Pt island (see

SEM picture, Figure D8), which is not completely active in the whole surface.

[000529] Figure D 12 shows the effect of ammonia concentration on the performance of the electrode. The effect of ammonia concentration is negligible on the electrode performance. This is due to the fact that the active Pt sites have already adsorbed the NH3 needed for a continuous reaction. Due to this feature, the present electrochemical cell is operable using only trace amounts of ammonia and/or ethanol.

[000530] Figure D 13 depicts the effect of the concentration of OH on the electro-oxidation of ammonia. A larger concentration of OH causes a faster rate of reaction. The electrode maintains continuous activity, without poisoning, independent of the OH concentration.

[000531] Figure D 14 shows the evaluation of the electrode for the electro-oxidation of ethanol. Continuous electro-oxidation of ethanol in alkaline medium is achieved without surface blockage. The present layered catalyst is thereby useable to oxidize ethanol, as well as ammonia.

[000532] The present layered electrocatalyst is contemplated to be useable at temperatures ranging from -50 degrees Centigrade to 200 degrees Centigrade. In an embodiment, the electrocatalyst can be usable from 20 degrees Centigrade to 70 degrees Centigrade. In another embodiment, the electrocatalyst is operable from

60 degrees Centigrade to 70 degrees Centigrade.

[000533] The present layered electrocatalyst can also be operable from 20 degrees Centigrade to 60 degrees Centigrade, from 30 degrees Centigrade to 70 degrees Centigrade, from 30 degrees Centigrade to 60 degrees Centigrade, or from 40 degrees Centigrade to 50 degrees Centigrade.

[000534] It is contemplated that in an embodiment, a higher pressure can be used, enabling the present layered electrocatalyst to be operable at higher temperatures. The present layered electrocatalyst is contemplated to be useable at pressures ranging from less than 1 atm to 10 atm.

[000535] The schematic for the construction of an electrode formed using the present layered electrocatalyst the electrode is shown if Figure D7. The plating procedure can include two steps: 1. First layer plating and 2. Second layer plating.

[000536] First layer plating includes plating the carbon support with materials that show a strong affinity for OH. Examples include, but are not limited to Rh, Ru, Ni, and Pd. In one preferred embodiment, Rh is used. The first layer coverage should completely plate the carbon support. In some embodiments, the first layer coverage is at least 2 mg/cm of carbon fiber to guarantee a complete plating of the carbon support. In other embodiments, the first layer coverage can be 2.5 mg/cm, 3.0 mg/cm, 3.5 mg/cm, or more.

[000537] Second layer plating includes plating the electrode with materials that have a strong affinity for the oxidation of ammonia and/or ethanol. Examples include: Pt and Ir. Monometallic deposition and/or bimetallic deposition of these materials can be performed. Ratios of PtIr can range from 100% Pt-0% Ir to 50% Pt-50% Ir.

[000538] Table DI summarizes the plating conditions for the anode and the cathode of the electrochemical cell. After plating the Rhodium, the electrode is weighted. The weight corresponds to the Rhodium loading. Then, the Platinum is deposited on top of the Rhodium. After the procedure is completed, the electrode is measured again. The measurement will correspond to the total loading. The Platinum loading is obtained by subtracting the total loading from the previous Rhodium measurement. The relation of Platinum to Rhodium is then calculated as the percentage of fixed loading. Because the loading depends on the length of the fiber, another measurement should be calculated. It is known that 10 cm of fiber weights 39.1 mg, and because the weight of the fiber is known, then by proportionality, it can be known the length of the total fiber that is being used in each electrode.

[000539] Table DII summarizes the general conditions of a plating bath useable to create the electrodes. During the entire plating procedure, the solution was mixed to enhance the transport of the species to the carbon support.

[000540] Table Dili shows examples of some electrode compositions, lengths, and loadings of active metals.

Table DI Conditions for Electro-plating Technique in the Deposition of Different

Metals on the Carbon Fibers and/or Carbon Nanotubes

Table DII General Conditions of the Plating Bath

Table Dili Examples of some Electrode Compositions and Loadings

[000541] For example, in a solution stirred at 60 rpm, at a temperature of 78 degrees centigrade, the platinum and iridium salts dihydrogen hexachloroplatinate (IV) (H₂PtCl₆-OH₂O - 38% Pt - Alfa Aesar® Item No. 11051), and iridium chloride (IrCl₃ - 55% Ir Alfa Aesar Item No. 11030) from Alfa Aesar, were added to a bath of IM hydrochloric acid. The purity of both salts were 99.9% (metal basis). Salt concentrations can be varied depending on the desired net loading of the platinum and iridium. For platinum salt, 90mg net/38% Pt in salt = 236 mg of Pt salt needed for bath. The same calculation applies Ir, but the purity of iridium in the salt is 55%. The anode used in this example was 4 cm x 4 cm Pt foil (0.102 mm thick 99.95% from ESPI Metals).

[000542] The cathode was weighed before plating to allow determining the mass of metal deposited. The potential was maintained at -0.1 volts versus an Ag/ AgCl electrode. The cathode was removed and rinsed with ultrapure water, then weighed to determine the amount of Pt-Ir deposited. It is contemplated that approximately 340 mg of Pt-Ir can be plated in about 1.6 hours.

[000543] To plate the layered electrocatalyst with only platinum, the same conditions can be used, however only dihydrogen hexachloroplatinate (IV) (H₂PtCl₆-OH₂O - 38% Pt) is used. The plating potential in this example is -0.12 V vs Ag/ AgCl.

[000544] To plate Rh, identical conditions can be used, except that the catalytic salt would be Rhodium (III) chloride hydrate (Alfa Aesar Item No. 11032 - 42% Rh). The electrodeposition potential would be -0.11 V vs. Ag/ AgCl.

[000545] To plate Ru identical conditions can be used, except that the catalytic salt would be Ruthenium (III) chloride (Alfa Aesar Item No. 11043 - 50% Ru). The electrodeposition potential would be -0.12 V vs. Ag/ AgCl.

[000546] To plate the layered electrocatalyst with Ru-Pt, the same conditions can be used, except that the catalytic salts would be Ruthenium (III) chloride (Alfa Aesar Item No. 11043 - 50% Ru) and Dihydrogen hexachloroplatinate (IV) (H₂PtCl₆-OH₂O - 38% Pt). The electrodeposition potential would be -0.10 V vs. Ag/AgCl.

[000547] To plate Ru-Pt-Ir, the same conditions can be used, except that the catalytic salts would be Rhodium (III) chloride hydrate (Alfa Aesar Item No. 11032 - 42% Rh), Dihydrogen hexachloroplatinate (IV) (Alfa Aesar Item No. 11051 - 38% Pt) - 38% Pt), and Iridium chloride (Alfa Aesar Item No. 11030 - 55% Ir). The electrodeposition potential would be -0.11 V vs. Ag/ AgCl.

[000548] To plate the layered electrocatalyst with nickel, a solution containing 280 g/L Nickel (II) sulfate, 40 g/L Nickel (II) chloride hexahydrate, and 30 g/L Boric acid (all from Fisher Scientific™) can be solvated with HPLC ultrapure water, then heated to 45 degrees Centigrade and mixed. An anode prepared from 0.127 mm thick Nickel foil (99+% from Alfa Aesar), that is twice the size of the cathode can be used. Using an Ag/AgCl reference electrode, Ni can be plated with high efficiencies at a potential of -0.8 V.

[000549] Referring now to Figure Dl, Figure Dl depicts an embodiment of the present layered catalyst.

[000550] A carbon support (26) is shown integrated with a conductive metal (90). While Figure Dl depicts the carbon support (26) adhered to a conductive metal plate, the carbon support (26) could also be integrated with conductive metals via winding, such as by winding carbon fibers around titanium gauze, or through other means.

[000551] A first metal plating layer (28) is disposed on the carbon support (26). A second metal plating layer (30) is shown partially disposed on the first metal plating layer (28).

[000552] While Figure Dl depicts the second metal plating layer (30) partially disposed on the first metal plating layer (28), the second metal layer (30) can partially or wholly cover the first metal plating layer (28).

[000553] Both metal plating layers (28, 30) can have uniform or varying thickness, including one or more perforations or portions that do not cover the carbon support (26).

[000554] Referring now to Figure D2, a diagram of an embodiment of a method for making the present layered catalyst is shown.

[000555] Figure D2 depicts that the method includes binding a carbon support with a conductive metal, such that the carbon support contacts the conductive metal, to form a bound carbon support (100).

[000556] The bound carbon support is then soaked in an electroplating bath (102). The electroplating bath includes: an anode at least twice the size of the bound carbon support, an aqueous carrier with an electrolyte, and a salt of a first plating metal having a mass three to five times the mass of the first plating metal to be deposited to the bound carbon support.

[000557] An electrical current is applied to the bound carbon support (104), thereby causing the first plating metal to be plated from the salt to the bound carbon support, forming the layered electrocatalyst.

[000558] It should be understood that the method can be repeated by placing the layered catalyst in a second electroplating bath having a salt of a second plating metal, to provide a second layer of a second metal to the layered electrocatalyst. Any number of layers of any combination of metals can be deposited on the layered electrocatalyst, as needed, enabling the present layered electrocatalyst to be customized to meet the needs of a user. While these embodiments have been described with emphasis on the embodiments, it should be understood that within the scope of the appended claims, the embodiments might be practiced other than as specifically described herein.

Claims

What is claimed is:

Al. An electrochemical cell for causing a reaction that produces hydrogen, the electrochemical cell comprising:

a first electrode comprising: at least one layered electrocatalyst, wherein the at least one layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

a second electrode comprising a conductor;

a basic electrolyte;

a member of the group consisting of: ammonia, ethanol, or combinations thereof; and

electrical current in communication with the first electrode.

A2. The electrochemical cell of claim 1, wherein the at least one layered catalyst further comprises at least one second metal layer deposited on the carbon support, wherein the at least one second metal layer is active to OH adsorption and inactive to the target species, and wherein the at least one second metal plating layer has a thickness ranging from 10 nanometers to 10 microns.

A3. The electrochemical cell of claim 1, wherein the electrical current is provided from a power generation system.

A4. The electrochemical cell of claim 1, wherein the electrochemical cell produces hydrogen, nitrogen, carbon dioxide, or combinations thereof.

A5. The electrochemical cell of claim 1, wherein the basic electrolyte has a volume that exceeds stoichiometric proportions of the reaction.

A6. The electrochemical cell of claim 1, wherein the basic electrolyte has a concentration ranging from 0.1M to 7M.

A7. The electrochemical cell of claim 1, wherein the at least one active metal layer is electrodeposited by sputtering, electroplating, vacuum electrodeposition, or combinations thereof.

A8. The electrochemical cell of claim 1, wherein the at least one active metal layer comprises rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

A9. The electrochemical cell of claim 1, wherein the ammonia, ethanol, or combinations thereof, has a concentration of ranging from 0.01 Molar to 5 Molar.

AlO. The electrochemical cell of claim 1, wherein the second electrode evolves hydrogen in the presence of an alkaline media.

Al l. The electrochemical cell of claim 1, wherein the second electrode comprises carbon, platinum, rhenium, palladium, nickel, Raney Nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, another electrode, or combinations thereof.

Al 2. The electrochemical cell of claim 1, wherein the first and second electrodes each comprise a layered electrocatalyst.

Al 3. The electrochemical cell of claim 1, wherein the first electrode, the second electrode, or combinations thereof, comprise a rotating disk electrode, a rotating ring electrode, a cylinder electrode, a spinning electrode, an ultrasound vibration electrode, or combinations thereof.

A14. The electrochemical cell of claim 1, further comprising a hydrophilic membrane.

Al 5. The electrochemical cell of claim 14, wherein the hydrophilic membrane exchanges only hydroxide.

A16. The electrochemical cell of claim 14, wherein the hydrophilic membrane comprises polypropylene, polyamide, another hydrophilic polymer, or combinations thereof.

Al 7. The electrochemical cell of claim 1, further comprising a separator.

A18. The electrochemical cell of claim 17, wherein the separator comprises polypropylene, glassy carbon, or combinations thereof. Al 9. A method for making an electrochemical cell adapted for evolving hydrogen, the method comprising the steps of:

forming a first electrode by combining at least one active metal layer with a carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

providing a second electrode comprising a conductor;

securing the first electrode and the second electrode in a housing comprising at least one inlet and at least two outlets, wherein a space exists between the first electrode and the second electrode;

providing a basic electrolyte to the housing;

providing ammonia, ethanol, or combinations thereof, to the housing;

sealing the housing; and

connecting a power source to the first electrode and the second electrode and providing current from the power source evolving hydrogen.

A20. The method of claim 19, wherein the step of forming a first electrode further comprises combining at least one second metal layer and the at least one active metal layer with the carbon support, wherein the at least one second metal layer is active to

OH adsorption and inactive to the target species, and wherein the at least one second metal plating layer has a thickness ranging from 10 nanometers to 10 microns.

A21. The method of claim 19, further comprising placing a separator or membrane in the housing between the first electrode and the second electrode.

A22. The method of claim 21, wherein the first electrode, the second electrode, or combinations thereof, are deposited on the separator or membrane.

A23. The method of claim 19, wherein the power source is a solar panel, an AC power source, a DC power source, a wind power source, a fuel cell, a battery, other similar power sources, or combinations thereof.

A24. The method of claim 19, wherein the step of connecting a power source to the first electrode and the second electrode comprises connecting the power source to a power input of the housing.

A25. The method of claim 19, wherein the housing further comprises at least one flow controller.

A26. The method of claim 19, wherein the fuel, the basic electrolyte, or combinations thereof, are provided to the housing through the at least one inlet.

A27. The method of claim 26, wherein the basic electrolyte is provided to the housing through the at least one inlet simultaneously with the fuel.

A28. The method of claim 26, wherein the basic electrolyte is provided to the housing through a first inlet and the fuel is provided to the housing through a second inlet.

A29. The method of claim 19, further comprising providing a controller to the housing, wherein the controller limits the voltage of the power source to no more than 1 volt.

A30. The method of claim 19, further comprising providing a sensor in at least one of the outlets for detecting ammonia, ethanol, or combinations thereof and deactivating the electrochemical cell if ammonia, ethanol, or combinations thereof are detected.

A31. A method for making an electrochemical cell adapted for evolving hydrogen, the method comprising the steps of:

providing a housing comprising a second electrode, at least one inlet, and at least two outlets;

securing the first electrode in the housing, wherein a space exists between the first electrode and the second electrode;

providing a basic electrolyte to the housing;

providing ammonia, ethanol, or combinaions thereof, to the housing; sealing the housing; and

connecting a power source to the first electrode and the second electrode and providing current from the power source.

A32. An electrochemical cell stack comprising:

a plurality of electrochemical cells formed by the method of claim 19,

wherein the plurality of electrochemical cells are connected in series, parallel, or combinations thereof.

A33. The electrochemical cell stack of claim 32, further comprising a bipolar plate disposed between at least two of the electrochemical cells, wherein the bipolar plate comprises an anode electrode, a cathode electrode, or combinations thereof.

A34. The electrochemical cell stack of claim 32, wherein the electrochemical cell stack has a cylindrical shape, a prismatic shape, a spiral shape, a tubular shape, or combinations thereof.

A35. The electrochemical cell stack of claim 32, wherein at least a first of the electrochemical cells comprises:

a first electrode comprising: at least one layered electrocatalyst formed of at least one active metal layer electrodeposited on a carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns; and

a second electrode comprising a conductor,

wherein at least a second of the electrochemical cells comprises:

a third electrode comprising a second layered electrocatalyst formed of at least one active metal layer electrodeposited on the carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns,

and wherein the second electrode functions as a cathode for both the first of the electrochemical cells and the second of the electrochemical cells.

A36. An electrochemical cell stack comprising:

a plurality of anode electrodes each comprising at least one layered electrocatalyst formed of at least one active metal layer deposited on the carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

at least one cathode electrode comprising a conductor;

a basic electrolyte in contact with each of the plurality of anode electrodes and the at least one cathode electrode;

ammonia, ethanol, or combinations thereof; and

electrical current in communication with the plurality of anode electrodes..

A37. The electrochemical cell stack of claim 36, wherein the at least one cathode electrode further comprises a hydrogen-permeable membrane.

A38. The electrochemical cell stack of claim 36, further comprising a fuel and current inlet in communication with each of the plurality of anodes simultaneously.

A39. The electrochemical cell stack of claim 36, wherein the electrochemical cell stack is operable at a pressure ranging from less than 1 atm to 10 atm, a temperature ranging from -50 degrees Centigrade to 200 degrees Centigrade, or combinations thereof.

Bl. A fuel cell utilizing ammonia, ethanol, or combinations thereof, wherein the fuel cell comprises:

a housing;

an anode disposed within the housing, the anode comprising at least one layered electrocatalyst, wherein the at least one layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to OH adsorption and inactive to ammonia, ethanol, or combinations thereof, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

at least one second metal layer at least partially deposited on the at least one active metal layer, wherein the at least one second metal layer is active to ammonia, ethanol, or combinations thereof, and wherein the at least one second metal layer has a thickness ranging from 10 nanometers to 10 microns;

a basic electrolyte disposed within the housing adjacent the anode;

a cathode disposed within the housing adjacent the basic electrolyte, wherein the cathode comprises a conductor;

ammonia, ethanol, or combinations thereof disposed within the housing in communication with the anode; and

an oxidant disposed within the housing in communication with the cathode for connecting with a power conditioner, a load, or combinations thereof,

wherein the power conditioner, the load, or combinations thereof, is in communication with the anode which oxidizes the ammonia, ethanol, or combinations thereof, allowing the fuel cell to form a current.

B2. The fuel cell of claim 1, wherein the ammonia, ethanol, or combinations thereof, has a concentration ranging from 0.01 M to 5.0 M.

B3. The fuel cell of claim 1, wherein the ammonia, ethanol, or combinations thereof comprises a liquid, a gas, or combinations thereof.

B4. The fuel cell of claim 1, wherein the oxidant comprises air, oxygen, or combinations thereof.

B5. The fuel cell of claim 1, wherein the oxidant has a pressure ranging from less than 1 atm to 10 atm.

B6. The fuel cell of claim 1 , wherein the basic electrolyte has a volume that exceeds stoichiometric proportions of the reaction.

B7. The fuel cell of claim 1 , wherein the basic electrolyte has a concentration ranging from 0.1M to 7M.

B8. The fuel cell of claim 1, wherein the concentration of basic electrolyte is 2 to 5 times greater than the concentration of the ammonia, ethanol, or combinations thereof.

B9. The fuel cell of claim 1, wherein the active metal layer comprises, rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

BlO. The fuel cell of claim 1, wherein the second electrode comprises carbon, platinum, rhenium, palladium, nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, or combinations thereof.

BI l. The fuel cell of claim 1 , wherein the first and second electrodes each comprise a layered catalyst.

B12. The fuel cell of claim 1, wherein the first electrode, the second electrode, or combinations thereof, comprise a rotating disc electrode, a rotating ring electrode, a cylinder electrode, a spinning electrode, an ultrasound vibration electrode, or combinations thereof.

B13. The fuel cell of claim 1, further comprising an ionic exchange membrane or separator disposed between the anode and the cathode.

B14. The fuel cell of claim 14, wherein the ionic exchange membrane or separator comprises polypropylene, polyamide, another polymer, copolymers thereof, glassy carbon, or combinations thereof.

B 15. A fuel cell stack comprising :

a plurality of fuel cells each in communication with an oxidant and a fuel supply, wherein the plurality of fuel cells is connected in series, parallel, or combinations thereof, wherein at least one of the fuel cells comprises an anode comprising at least one layered electrocatalyst, wherein the at least one layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to OH adsorption and inactive to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns; and

at least one second metal layer at least partially deposited on the at least one active metal layer, wherein the at least one second metal layer is active to the target species, and wherein the at least one second metal layer has a thickness ranging from 10 nanometers to 10 microns,

wherein the plurality of fuel cells generates electrical current when connected to a load.

B16. The fuel cell stack of claim 15, wherein the at least one of the fuel cells further comprises:

a housing, wherein the anode is disposed in the housing;

a basic electrolyte disposed within the housing adjacent the anode;

a cathode disposed within the housing adjacent the basic electrolyte, wherein the cathode comprises a conductor.

B17. The fuel cell stack of claim 15, further comprising a bipolar plate disposed between at least two of the fuel cells, wherein the bipolar plate comprises an anode electrode, a cathode electrode, or combinations thereof.

B 18. The fuel cell stack of claim 15, wherein the fuel cell stack has a cylindrical shape, a prismatic shape, a spiral shape, a tubular shape, or combinations thereof.

B 19. The fuel cell stack of claim 15, wherein the at least a first of the fuel cells further comprises:

a cathode comprising a conductor,

wherein at least a second of the fuel cells comprises:

a second anode comprising the at least one layered electrocatalyst,

and wherein the cathode functions as the cathode for both the first of the fuel cells and the second of the fuel cells.

B20. The fuel cell stack of claim 15, wherein the fuel cell stack is operable at a pressure ranging from less than 1 atm to 10 atm, a temperature ranging from -50 degrees Centigrade to 200 degrees Centigrade, or combinations thereof.

B21. A cell stack comprising:

a plurality of hydrogen fuel cells, each in communication with a load, an oxidant, and a fuel supply, wherein the plurality of hydrogen fuel cells is connected in series, parallel, or combinations thereof, wherein each of the hydrogen fuel cells comprises an anode comprising at least one layered electrocatalyst, and wherein the at least one layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to OH adsorption and inactive to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

at least one second metal layer at least partially deposited on the at least one active metal layer, wherein the at least one second metal layer is active to the target species, and wherein the at least one second metal layer has a thickness ranging from 10 nanometers to 10 microns;

a plurality of electrochemical cells, wherein at least one of the electrochemical cells comprises a first electrode comprising the at least one layered electrocatalyst,

wherein the plurality of electrochemical cells produces hydrogen for powering the plurality of fuel cells,

and wherein the plurality of fuel cells produces current sufficient to power the plurality of electrochemical cells while producing a net power gain.

B22. An electric consuming device assemblage comprising:

at least electric consuming device;

at least one fuel cell, wherein the at least one fuel cell comprises an anode comprising at least one layered electrocatalyst, and wherein the at least one layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one electrochemical cell, wherein the at least one electrochemical cell comprises a first electrode comprising the at least one layered electrocatalyst,

wherein the at least one electrochemical cell produces hydrogen for powering the at least one fuel cell,

and wherein the at least one fuel cell produces current for powering both the at least one electrochemical cell and the at least one electric consuming device.

B23. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the voltage applied to the at least one electrochemical cell.

B24. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the pressure of the at least one electrochemical cell, the at least one fuel cell, or combinations thereof.

B25. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the temperature of the at least one electrochemical cell, the at least one fuel cell, or combinations thereof.

B26. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the pH of the at least one electrochemical cell, the at least one fuel cell, or combinations thereof.

B27. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the flow of ammonia, ethanol, or combinations thereof, into the at least one electrochemical cell, the at least one fuel cell, or combinations thereof.

B28. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the flow of resultant gas out of the at least one electrochemical cell.

B29. The electric consuming device assemblage of claim 22, further comprising a controller for regulating load applied to the at least one electrochemical cell.

B30. The electric consuming device assemblage of claim 22, further comprising a controller for regulating the heat flux of the at least one electrochemical cell, the at least one fuel cell, or combinations thereof. Cl. An electrochemical method for producing hydrogen by applying an electric current to ammonia, ethanol, or combinations thereof, causing a reaction, the method comprising:

forming an anode comprising a layered electrocatalyst, wherein the layered electrocatalyst comprises

a carbon support integrated with a conductive metal; and

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to ethanol, ammonia, or combinations thereof, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns;

providing a cathode comprising a conductor;

disposing a basic electrolyte between the anode and the cathode;

flowing a fuel to the basic electrolyte;

applying an eletric current to the anode causing oxidation of the fuel, evolving hydrogen at the cathode.

C2. The electrochemical method of claim 1 , wherein the fuel is flowed continuously to the basic electrolyte.

C3. The electrochemical method of claim 1, wherein the layered electrocatalyst further comprises at least one second metal layer deposited on the carbon support, wherein the at least one second metal layer is active to OH adsorption and inactive to the target species, and wherein the at least one second metal plating layer has a thickness ranging from 10 nanometers to 10 microns.

C4. The electrochemical method of claim 1, further comprising the step of controlling the electric current to control the output of the hydrogen.

C5. The electrochemical method of claim 1, further comprising the step of regulating the electric current to maintain a voltage below one volt.

C6. The electrochemical method of claim 1, wherein the step of forming the anode comprises using sputtering, electroplating, vacuum electrodeposition, or combinations thereof to deposit the at least one active metal layer on the carbon support.

C7. The electrochemical method of claim 1, wherein the fuel comprises ammonia, ethanol, or combinations thereof.

C8. The electrochemical method of claim 1, wherein the at least one active metal layer comprises rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

C9. The electrochemical method of claim 1, wherein the cathode comprises carbon, platinum, rhenium, palladium, nickel, iridium, vanadium, cobalt, iron, ruthenium, molybdenum, or combinations thereof.

ClO. The electrochemical method of claim 1, further comprising placing a membrane or separator between the anode and the cathode.

CI l. The electrochemical method of claim 1 , wherein the electric current is provided using a power generation system, a solar panel, an AC power source, a DC power source, a wind power source, a fuel cell, a battery, other similar power sources, or combinations thereof.

C 12. A method for surface buffered, assisted electrolysis of water, the method comprising:

forming an anode comprising a layered electrocatalyst, wherein the layered electrocatalyst comprises:

a carbon support integrated with a conductive metal;

at least one active metal layer at least partially deposited on the carbon support, wherein the at least one active metal layer is active to a target species, and wherein the at least one active metal layer has a thickness ranging from 10 nanometers to 10 microns; and

at least one second metal layer deposited on the at least one active metal layer, wherein the at least one second metal layer is active to OH adsorption and inactive to the target species, and wherein the at least one second metal plating layer has a thickness ranging from 10 nanometers to 10 microns; providing a cathode comprising a conductor;

disposing an aqueous basic electrolyte comprising water between the anode and the cathode;

disposing a buffer solution within the aqueous basic electrolyte; and

applying an electric current to the anode causing oxidation of the water, evolving hydrogen at the cathode.

C13. The method of claim 12, wherein the buffer solution comprises ammonia, ethanol, propanol, or combinations thereof.

C 14. The method of claim 13, wherein the buffer solution has a concentration ranging from 1 ppm to 100 ppm.

C15. The method of claim 12, further comprising the step of controlling the electric current to control the rate at which the hydrogen is evolved at the cathode.

C16. The method of claim 12, further comprising the step of regulating the electric current to maintain a voltage below one volt.

C 17. A method for open circuit electrolysis of water, the method comprising:

a carbon support integrated with a conductive metal;

disposing a buffer solution within the aqueous basic electrolyte, thereby causing oxidation of the basic electrolyte to evolve hydrogen at the cathode while producing water at the anode.

C 18. The method of claim 17, wherein the buffer solution comprises ammonia, ethanol, propanol, or combinations thereof.

C 19. The method of claim 17, wherein the buffer solution has a concentration ranging from 1 ppm to 100 ppm.

Dl. A layered electrocatalyst for an electrochemical process for oxidizing ammonia, ethanol, or combinations thereof, the layered electrocatalyst comprising:

a carbon support integrated with a conductive metal;

at least one first metal plating layer at least partially deposited on the carbon support, wherein the at least one first metal plating layer is active to OH adsorption and inactive to a target species, and wherein the at least one first metal plating layer has a thickness ranging from 10 nanometers to 10 microns;

at least one second metal plating layer at least partially deposited on the at least one first metal plating layer, wherein the at least one second metal plating layer is active to the target species, and wherein the at least one second metal plating layer has a thickness ranging from 10 nanometers to 10 microns, forming a layered electrocatalyst.

D2.The layered electrocatalyst of claim 1, wherein the target species comprises ammonia, ethanol, or combinations thereof.

D3.The layered electrocatalyst of claim 1, wherein the at least one second metal plating layer has a first thickness ranging from 0 to 500 nanometers on a first portion of the carbon support and a second thickness ranging from 0 to 500 nanometers on a second portion of the carbon support.

D4.The layered electrocatalyst of claim 1 wherein the carbon support comprises carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, nano-sized carbon fibers, nano-sized carbon tubes, carbon sheets, or combinations thereof.

D5.The layered electrocatalyst of claim 1, wherein the at least one first plating layer comprises rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

Dβ.The layered electrocatalyst of claim 1, wherein the at least one second plating layer comprises platinum, iridium, or combinations thereof.

D7.The layered electrocatalyst of claim 6, wherein the platinum to iridium is used in a ratio that ranges from 99.99:0.01 to 50:50 platinum:iridium, respectively.

D8.The layered electrocatalyst of claim 1, wherein the at least one first metal plating layer, the at least one second metal plating layer, or combinations thereof, are a continuous layer.

D9.A sensor for detecting ammonia, ethanol, or combinations thereof, the sensor comprising:

a carbon support integrated with a conductive metal; and

at least one active metal plating layer at least partially deposited on the carbon support, wherein the at least one active metal plating layer has a thickness ranging from 10 nanometers to 10 microns, and wherein the at least one active metal plating layer is active to ammonia, ethanol, or combinations thereof, and detects the ammonia, ethanol, or combinations thereof at a concentration of at least 0.1 Millimolar,

wherein the sensor produces a potential proportional to the concentration of ammonia, ethanol, or combinations thereof when an electric current is applied to the at least one active metal plating layer.

DlO. The sensor of claim 9, further comprising:

at least one additional metal plating layer at least partially deposited on the carbon support, wherein the at least one additional metal plating layer has a thickness ranging from 10 nanometers to 10 microns, and wherein the at least one additional metal plating layer is active to OH adsorption and inactive to the ammonia, ethanol, or combinations thereof.

DI l. The sensor of claim 9, wherein the at least one active metal plating layer comprises rhodium, rubidium, iridium, rhenium, platinum, palladium, copper, silver, gold, nickel, iron, or combinations thereof.

D12. The sensor of claim 10, wherein the at least one additional metal plating layer comprises platinum, iridium, or combinations thereof.

D13. The sensor of claim 9, wherein the carbon support comprises carbon fibers, carbon tubes, carbon microtubes, carbon microspheres, nano-sized carbon fibers, nano-sized carbon tubes, carbon sheets, or combinations thereof.

D 14. A method for making a layered electrocatalyst for oxidation of ammonia, ethanol, or combinations thereof in a basic electrolyte, the method comprising:

binding a carbon support with a conductive metal, wherein the carbon support contacts the conductive metal, forming a bound carbon support;

forming a layered electrocatalyst by soaking the bound carbon support in an electroplating bath having an anode at least twice the size of the bound carbon support and applying an electrical current to the bound carbon support, wherein the electroplating bath comprises:

an aqueous carrier with an electrolyte; and

a salt of a first plating metal in the aqueous carrier, wherein the salt of the first plating metal has a mass three to five times a mass of the first plating metal to be deposited on the bound carbon support.

D15. The method of claim 14, further comprising the step of pretreating the carbon support to remove at least a portion of a coating on the carbon support.

D16. The method of claim 14, wherein the electroplating bath has a temperature ranging from 25 degrees Centigrade to 80 degrees Centigrade.

D17. The method of claim 14, wherein a standard hydrogen electrode is disposed in the electroplating bath.

D 18. The method of claim 17, wherein the electrical current provides a voltage potential ranging from -0.2 volts to -1.0 volts versus the standard hydrogen electrode.

D19. The method of claim 14, wherein the anode comprises a foil formed from platinum, ruthenium, iridium, or alloys thereof.

D20. The method of claim 14, further comprising providing constant stirring to the electroplating bath.

D21. The method of claim 14, wherein the electrolyte is acidic or basic with a concentration ranging from IM to 5 M.

D22. The method of claim 21, wherein the electrolyte is hydrochloric acid, boric acid, or combinations thereof.

D23. The method of claim 14, further comprising the step of controlling the electric current to regulate the plating of the cathode.

D24. The method of claim 14, further comprising the step of measuring the loading of the first plating metal on the carbon support.

D25. The method of claim 14, wherein the salt of the first plating metal comprises a halide salt.

D26. The method of claim 14, further comprising the steps of:

soaking the layered electrocatalyst in a second electroplating bath having a second anode at least twice the size of the layered electrocatalyst and applying an electrical current to the layered electrocatalyst, wherein the second electroplating bath comprises:

a second aqueous carrier with a second electrolyte; and

a second salt of a second plating metal in the second aqueous carrier, wherein the second salt of the second plating metal has a mass three to five times a mass of the second plating metal to be deposited on the layered electrocatalyst.