WO2001028025A1 - Cellules electrochimiques modifiees magnetiquement - Google Patents

Cellules electrochimiques modifiees magnetiquement Download PDF

Info

Publication number
WO2001028025A1
WO2001028025A1 PCT/US2000/028242 US0028242W WO0128025A1 WO 2001028025 A1 WO2001028025 A1 WO 2001028025A1 US 0028242 W US0028242 W US 0028242W WO 0128025 A1 WO0128025 A1 WO 0128025A1
Authority
WO
WIPO (PCT)
Prior art keywords
magnetic
fuel cell
cathode
anode
electron
Prior art date
Application number
PCT/US2000/028242
Other languages
English (en)
Inventor
Johna Leddy
Lois Anne Zook
Sudath Amarasinghe
Drew Dunwoody
Hachull X. Chung
Catherine Spolar
Shelley D. Minteer
Original Assignee
University Of Iowa Research Foundation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University Of Iowa Research Foundation filed Critical University Of Iowa Research Foundation
Priority to AU11985/01A priority Critical patent/AU1198501A/en
Publication of WO2001028025A1 publication Critical patent/WO2001028025A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H01M8/0612—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates generally to an improved fuel cell apparatus, and methods of use thereof.
  • the present invention relates an apparatus and methods of its use with respect to fuel cells having enhanced electrical current and power outputs that result from magnetic modification of one or both of the anode and cathode - the magnetic modification being effected in a preferred embodiment via a microstructured magnetic composite material that is disposed on the desired electrode(s).
  • the improved fuel cell apparatus of the present invention is also highly resistant to electrode passivation.
  • a fuel cell 1 comprises a cathode 12, an anode 10, and a separator 14 disposed between the anode and the cathode.
  • an oxidant such as O z 18
  • a fuel such as H, 16
  • An external resistive load 4 applies to the entity that harnesses the energy of the fuel cell via external circuit 2.
  • One or more noble metal catalysts 8 and 6 are typically employed both on the cathode 12 and the anode 10, for example, platinum.
  • the separator 14 may be made of an ionic membrane, such as Nafion®, which functions as a proton exchange membrane (PEM). Water 22 may be produced by such a fuel cell system.
  • An encasement 3 is used to confine the contents of a fuel cell, and to isolate such contents from the surrounding environment.
  • the basic objective of a fuel cell is to allow a reaction between a fuel (e.g., hydrogen, methanol, ethanol, propanol, acetaldehyde, methane, etc.) and an oxidant (e.g., oxygen, hydrogen peroxide), which normally react spontaneously (and often violendy), to discharge in a controlled manner.
  • a fuel e.g., hydrogen, methanol, ethanol, propanol, acetaldehyde, methane, etc.
  • an oxidant e.g., oxygen, hydrogen peroxide
  • Fuel cells combine the best characteristics of a battery and a combustion engine. Similar to the combustion engine, they are not recharged electrically, and output power is realized as long as fuel is provided. Similar to the battery, fuel cells are electrical devices capable of providing power, and theoretically, are not subject to a combustion engine's Carnot limitations. The expansion and contraction of pistons limit heat engines to about 40% of their theoretical power efficiency, and about 25% as their practical efficiency under optimal conditions. In contrast, fuel cells approach 100% efficiency in theory, and have been demonstrated to operate at better than 90% efficiency in practice.
  • PEM fuel cells are fuel cells in which the separator is a proton exchange membrane.
  • One commonly used PEM is Nafion®, which is a perfluorinated sulfonic acid resin.
  • PEM fuel cells are examples of low temperature operating fuel cells because they typically operate at or below about 100°C.
  • oxygen or atmospheric air serves as the oxidant
  • hydrogen serves as the fuel.
  • a fuel cell that runs on hydrogen and oxygen is designated an H 2 /0 2 fuel cell; i.e., the fuel/oxidant convention.
  • the PEM fuel cell illustrated in Figure 1 employs hydrogen as a feed 16 to anode 10, and oxygen in air as a feed 18 to cathode 12. Those reactants decompose electrolytically to yield water 22 at the cathode.
  • the hydrogen and oxygen are separated by a proton exchange membrane 14 (such as Nafion®) to prevent, among other things, thermal decomposition of the fuels at noble metal catalyst 6, 8.
  • the reactions at cathode 12 and anode 10 can be summarized as follows:
  • a fuel cell typically runs under non-equilibrium conditions and is thus subject to kinetic limitations.
  • the cathode reaction increasingly kinetically limits performance as current demand increases, which is reflected in a drop in the fuel cell's voltage output; simultaneously, a second reaction path (the two-electron/two-proton reduction of oxygen to peroxide) becomes increasingly favored.
  • This second reaction path consumes oxygen in two-electron steps with lower thermodynamic potential as follows:
  • the standard free energy of the reduction of oxygen to peroxide of Equation (5) is roughly 30% of the free energy available from the four-electron reduction of oxygen to water that is shown in Equation (4), and the current output from a fuel cell in which the two- electron reaction predominates is proportionately decreased due to the transfer of only two electrons, instead of four and the lower E 0 CL . ⁇ .
  • This effect especially when combined with the concomitantiy decreased maximum cell potential, yields a substantially lower fuel cell power output.
  • the efficiency of the cathode reaction in which the two-electron pathway predominates, or at least comprises a substantial proportion of the overall reaction, can be enhanced by increasing the concentration and/or pressure and flow rate of the feeds to the cathode 12 (i.e., protons and oxygen).
  • the proton flux typically is not limiting, as the proton exchange membrane (e.g., Nafion®) readily provides an ample supply of protons to meet the demand of the cathode reaction(s).
  • the flux of oxygen is increased (and the reaction is consequendy biased to favor the formation of water) by pressurizing the air feed to the cathode 12 to at least 2 to 10 atmospheres.
  • the kinetics for hydrogen oxidation in an H 2 /0 2 fuel cell are very rapid compared to the H 2 /0 2 kinetics of oxygen reduction.
  • the feed to cathode 12 is pressurized to at least roughly two times the pressure of the feed to anode 10.
  • the resulting change in the concentration of oxygen at cathode 12 shifts the reaction toward the desired electrolysis product, which is water.
  • a second impediment is that hydrogen is not the most convenient fuel because of its highly exothermic reactivity with oxygen, which can produce flames and/or explosion.
  • One solution to this problem is to use indirect reformation of an organic fuel, for example, by passing the organic fuel over a hot copper/zinc catalyst, which yields hydrogen that then is fed to anode 10.
  • direct reformation in which an organic fuel is fed direcdv to anode 10, would provide greater efficiency for the fuel cell system; however, the problem remains of electrode passivation due to by-products such as carbon monoxide.
  • separator 14 tends to imbibe organic fuels, which then cross separator membrane 14 and pass to cathode 12, where there is a direct reaction with the oxidant, including assistance from the catalyst.
  • separator membrane 14 short circuits the flow of electrons through the external circuit, which reduces the electrical current and power outputs to the external circuit of the fuel cell.
  • Magnetic field effects on chemical systems include effects on the rates of electron transfer (i.e., kinetic effects) in both homogeneous and heterogeneous systems; however, macroscopic thermodynamic effects generally are negligible.
  • Kinetic effects may be manifest in various areas, including effects on reaction rates, reaction pathways, and distribution of products.
  • the incidence of electron transfer reactions, in which electrons are transferred between molecules or ions, is ubiquitous throughout natural and technological systems, including biological energy production, ozone depletion, and technologies from photography through batteries, solar cells, fuel cells, and corrosion.
  • Electron transfer reactions can be characterized as either homogeneous or heterogeneous. If the reaction occurs in a single phase (i.e., solid, liquid, gas, or plasma) between two ions or molecules, the reaction is a homogeneous electron transfer. On the other hand, if the reaction occurs at an interface between two chemically/physically (-ussimilar phases (e.g., at the interface between an electrode and the surrounding solution, at the interface between two dissimilar solutions that are mixed together - but before they are totally mixed to uniformity, at the interface between a charged membrane and the surrounding solution, etc.), then the reaction is a heterogeneous electron transfer when one of the molecules/ions is on one side of the interface, and the other reactant is either a molecule or ion on the opposite side of the interface or in/at the interface, or it is the interface itself.
  • a single phase i.e., solid, liquid, gas, or plasma
  • the reaction is a homogeneous electron transfer.
  • the reaction occurs at an interface between two chemically
  • Uniform magnetic fields that are applied when a solution is placed between the poles of a magnet will have a negligible effect on the free energy of a typical chemical reaction.
  • the effect will be on the order of less than a Joule/mole, and more typically, less than 0.5 Joule/mole.
  • substantial microscopic effects may be realized, for example, when a chemical reaction occurs within 1 nm of a magnetic microparticle that is, for example, part of a magnetic composite applied to an electrode or other surface.
  • the magnetic field produced by a magnetic microparticle decreases over a distance x in proportion to x "3 .
  • the field experienced by a molecule 1 nm from a magnetic microparticle can be on the order of 10 21 times greater than the field experienced 1 cm from the same magnetic microparticle.
  • highly local magnetic effects can produce substantial effects when mass transport effects are present.
  • spin polarization which may be electron, nuclear, or electron-nuclear.
  • electron spin polarization effects have been studied in the laboratory (A.L. Buchachenko, 1976. "Magnetic effects in chemical reactions.” Russ. Chem. Rev. 45: 375-390. N.J. Turro & B. Kraeuder, 1980. "Magnetic field and magnetic isotope effects in organic photochemical reactions. A novel probe of reaction mechanisms and a method for enrichment of magnetic isotopes.” Accounts of Chemical Research 13: 369-377. U.E. Steiner & T. Ulrich, 1989. Chem. Rev. 89: 51. P.W.
  • Electron spin polarization refers to polarization between unpaired electrons on two different radicals or radical centers.
  • a radical pair is formed where the electron cloud of one species precesses around the vector of the applied field, and through interactions with the second unpaired electron, spin relaxations between high and low spin states are induced.
  • a common example of electron spin polarization or spin relaxation is intersystem crossing, where, for example, a species with one unpaired electron (a doublet, D) interacts with a second doublet to form a complex with two unpaired electrons (a triplet, T) that yields products with no unpaired electrons (a singlet, S). Theory restricts rate enhancements for singlet/ triplet conversions to ninefold (see Turro & Kraeutler, 1980, above).
  • Nuclear-nuclear spin polarization occurs between two nuclei in a magnetic field when the polarized nucleus on the first molecule polarizes the nucleus of the second molecule. No radicals are required, but one nucleus must be pre-polarized. Again, nuclear polarization effects are slow and small, especially when compared to electron and electron-nuclear spin polarization effects.
  • Electron-nuclear spin polarization occurs when the electron spin polarization on one species allows electronic currents generated by the precessing electron cloud to induce a secondary magnetic field at the nucleus of the second species.
  • magnetic effects can occur through electron and electron-nuclear spin polarization; for a radical and a singlet, only electron-nuclear spin polarization is possible.
  • electron-nuclear spin polarization allows a radical in a magnetic field to increase the electron exchange rate with a singlet.
  • Electron-nuclear spin polarization is also known as electron-nuclear cross- relaxation and dynamic polarization.
  • Electron-nuclear spin polarization causes hne broadening in nuclear magnetic resonance (NMR) and electron proton resonance (EPR) spectroscopy, and enhances signal intensity for NMR several hundred-fold (A. Carrington & A.D. McLaughlin, 1967. In: Introduction to Magnetic Resonance with Applications to Chemistry and Chemical Physics, pages 229-236. Harper and Row, N.Y., the contents of all of which are incorporated herein by reference).
  • Another object of the fuel cell invention is to provide an improved PEM (proton exchange membrane) fuel cell.
  • Another object of the present magnetically modified fuel cell invention is to provide an improved electrolytic cell.
  • Another object of the present magnetically modified fuel cell invention is to provide a fuel cell that facilitates electron transfer in heterogeneous and in homogeneous systems/environments.
  • Another object of the present magnetically modified fuel cell invention is to provide an improved fuel cell with enhanced power output.
  • Another object of the present magnetically modified fuel cell invention is to provide an improved fuel cell that has improved resistance to passivation.
  • Another object of the present magnetically modified fuel cell invention is to provide an improved fuel cell that has the capability of altering the product distribution of a chemical reaction.
  • One advantage of the present magnetically modified fuel cell invention is that it can enhance the flux of oxygen or other oxidant that is reduced at the cathode of a fuel cell.
  • Another advantage of the present magnetically modified fuel cell invention is that it can alter the product distribution of a chemical reaction.
  • Another advantage of the present magnetically modified fuel cell invention is that it can effect certain chemical reactions that otherwise are quantum mechanically forbidden or kinetically disfavored.
  • Another advantage of the present magnetically modified fuel cell invention is that, with magnetic modification of the cathode and operation at about 70°C, it can produce a maximum electrical current output that is at least about three times the maximum electrical current output of a conventional nonmagnetic fuel cell in operation at about 70°C.
  • Another advantage of the present magnetically modified fuel cell invention is that, with magnetic modification of both the cathode and the anode and operation at about 70°C, it can produce a maximum electrical current output that is at least about four times the maximum electrical current output of a conventional nonmagnetic fuel cell in operation at about 70°C.
  • Another advantage of the present magnetically modified fuel cell invention is that it can produce significant power and electrical current outputs under operation at room temperature (around 25°C), compared to a conventional nonmagnetic fuel cell operates very poorly at temperatures as low as room temperature.
  • Figure 1 is a schematic illustrating basic components of an H 2 /0 2 PEM fuel cell, including an anode and a cathode (each having a noble metal catalyst; here, platinum), and a separator (here, Nafion®).
  • a noble metal catalyst here, platinum
  • a separator here, Nafion®
  • Figure 2 shows the effects of temperature and degree of magnetic loading of cathodes with iron oxide magnets for fuel cells in plots of power versus potential.
  • curves of power versus potential are shown for samarium cobalt magnets loaded onto cathodes at 0.13 mg/cm 2 at 70°C.
  • Figure 3 shows curves of potential versus current for the same plots shown in Figure
  • Figure 4 shows the effects of pressure (1-3 arm) and magnetic loading of cathodes with iron oxide magnets for H 2 /0 2 fuel cells at 70°C. Potential versus current curves are shown for samarium cobalt loaded cathodes at a level of 0.13 mg/cm 2 at 70°C.
  • Figure 5A shows curves of power versus potential for the same experiments shown in Figure 4.
  • Figure 5B plots power density as a function of pressure.
  • Figure 6 shows the effects of temperature and magnetic loading of the cathode electrode on the power output of H 2 /0 2 fuel cells.
  • Figure 7 shows the effect of humidification temperature on magnetically modified cathode electrodes for H,/0 2 fuel cells when the fuel cell is at 20°C.
  • Figure 8 shows the effects of temperature (30 to 70°C) and magnetic loading of cathodes with iron oxide magnets for H 2 /air fuel cells in plots of potential versus current. In addition, results for samarium cobalt loaded cathodes at 0.13 mg/cm 2 are shown for 30 to 70°C.
  • Figure 9A shows curves of power versus potential for H 2 /air fuel cells under the conditions indicated in Figure 8.
  • Figure 9B plots the data as power density versus temperature in °C.
  • Figure 10 shows the curves of potential versus current, and power versus potential, for magnetically loaded cathode electrodes at 70°C and for pressure from 1 to 3 atmospheres.
  • Figure 11 shows the effects of cathode flow rates for magnetically loaded cathode electrodes in curves of potential versus current, and power versus potential for H 2 /air fuel cells at 70°C
  • Figure 12 shows the effects of magnetic loading and temperature (30-70°C) when both the cathode and anode of H 2 /0 2 fuel cells operating at one atmosphere.
  • the cathode magnetic loading is fixed at 0.2 mg/cm 2 and the anode load is varied.
  • Figure 13 shows curves of power versus potential for the cathode and anode magnetically modified electrodes of Figure 12.
  • Figure 14 shows curves of power versus potential for fuel cells operated at 25 to 70°C when both the cathode and the anode are loaded with different amounts of magnets.
  • Figure 15 shows curves of potential versus current for the same experiments indicated in Figure 14.
  • Figures 16A and 16B show curves of potential versus current, and power versus potential, when both cathode and anode are magnetically modified, and pressure is varied from 1 to 3 atmospheres.
  • Figures 17A and 17B contrast the effects of air (Figure 17A) versus 0 2 ( Figure 17B) when both cathode and anode are magnetically modified.
  • Figure 18 shows the effects of passivation (use of synthetic reformate containing hydrogen and 100 ppm of carbon monoxide) on anodes that are magnetically modified with iron oxide magnets, versus on anodes that are not magnetically modified.
  • Figure 19 shows the effects on current density of use of synthetic reformate (hydrogen plus 100 ppm of carbon monoxide) when the anode contains platinum/ruthenium catalyst, but no iron oxide magnets.
  • Figure 20 shows the current density response of a PEM fuel cell system with an anode operating with the benefit of 0.40 mg/cm 2 of iron oxide when synthetic reformate is imposed, including recovery when pure hydrogen subsequendy replaces the synthetic reformate at 960 minutes.
  • Figure 21 shows the beneficial effects of magnetic modification of both electrodes of a PEM fuel cell subjected to synthetic reformate (hydrogen plus 100 ppm of carbon monoxide).
  • Figure 22 contrasts "best results" for PEM fuel cell function with iron oxide magnetic modification of neither cathode nor anode, cathode only, and both cathode and anode, including in the presence of synthetic reformate (hydrogen plus 100 ppm of carbon monoxide).
  • Figure 23 compares oxidation currents as a function of the square root of the scan rate for magnetically modified electrodes of PEM fuel cells oxidizing ethanol, acetaldehyde, or acetic acid.
  • Figure 24 compares oxidation currents for organic fuels at nonmagnetic and magnetic composite modified electrodes.
  • Figure 25 presents voltammograms for various redox couples.
  • Figure 26 shows a plot of calculated versus experimental diffusion data.
  • the reaction begins with the doublet already polarized by an applied magnetic field, which is denoted as D*, where the asterisk indicates the species is polarized.
  • a doublet complex [J " D*] D is formed which can either undergo electron transfer to the products D* + S, or, through electron-nuclear spin polarization between S and D*, form a new doublet complex [ ⁇ - *] D , which can undergo transfer to form D* + S.
  • [i ⁇ *] 15 the polarized electron on D* has polarized the nucleus on S.
  • the stabiUty constant of intermolecular electron transfer, K describes the reversible formation of the first complex from the reactants.
  • the rate constants for electron transfer for the first and second complexes to form products are k tt , and k t , 2 , respectively.
  • the constants , ⁇ N , and ⁇ are the Bohr magneton, the Bohr nuclear magneton, and Planck's constant, respectively.
  • H is the external magnetic field strength in Gauss
  • A is the hyperfine coupling constant in Gauss.
  • ⁇ is the electronic ⁇ -factor
  • ⁇ is the nuclear ⁇ -factor, both of which are dimensionless.
  • the ⁇ - factors are measures of the magnetic properties of a species, and are determined by EPR. Because ⁇ - 2000 ⁇ , and g t and g ⁇ are comparable, the nuclear spin polarization term is negligible.
  • the hyperfine coupling term, A ⁇ / 2 is also neghgible.
  • the doublet complex [S* ⁇ 2 ] D is converted to a second doublet complex [Q*S*] D , which can be converted to the quartet complex ⁇ Q*S .
  • This latter complex can then dissociate into products.
  • the relaxation mechanism allows for rapid preequihbrium spin change. Given fast electron transfer from [S*0*] D , Equation 10 also describes the spin forbidden reaction.
  • Electron exchange reactions occur when an electron is passed from one molecular or ionic species to another. If the reactants are two different oxidation states of the same species (redox couples), and the products are the same as the reactants, then the reaction is known as a self exchange reaction (see Salikhov, Sagdeev, & Buchachenko, 1984, above); that is, M" + M" ⁇ l /V ⁇ 1 + M".
  • Electron exchange efficiency determines the enhancement, and depends on the distance between redox moieties as embedded in their concentration C*, the distance of closest approach for the moieties ⁇ 5in units of cm, the self- exchange rate constant k ( m ' units of M 'x ', and the physical diffusion coefficient D ml in units of cm 2 /s.
  • Electrochemical perturbation allows control of self exchange reactions and determination of D ⁇ , (see Buttry & Anson, 1983; Buttry & Anson, 1981; and White, Leddy,
  • Magnetic composites of magnetic microparticles provide a ready means of examining the effects of strong, local magnetic fields on self exchange reactions, and on electron-nuclear polarization in particular.
  • Fuel cells may be used to provide electrical current/voltage/power to an external device, to provide direct surface area for conducting synthetic chemical and electrochemical reactions, and to provide interfacial boundaries for such reactions.
  • the apparatus and method of use thereof of the present invention expand these applications to include the ability to facilitate chemical reactions that, under conditions of the common nonmagnetic electrode setup, are kinetically disfavored and/or quantum mechanically disallowed, including quantum mechanically spin disallowed.
  • Magnetic modification of one or both electrodes of a fuel cell apparatus permits application of intense magnetic fields at loci that are located at, or close to, the magnetically modified electrode(s), for example, on the order of within 10 nm from the magnetically modified electrode surface.
  • FIG. 2 a. H /0 2 Fuel Cells + Only Cathode Magnetically Modified. i. T CELL effects.
  • Figures 2, 3, 6 and 7 examine the effects of temperature of the fuel cells on function of the fuel cells.
  • curves of power versus potential are shown, with the temperature ranging from 25 to 70°C, when iron oxide magnets are loaded at values of 0.05 (0 ), 0.14 ( ⁇ ), 0.20 ( ⁇ ), 0.35 (O), and 0.40 (*) mg/cm 2 .
  • a second replicate of the 0.14 mg/cm 2 magnetic loading data are shown as (X).
  • the power versus potential curves for non-magnetically modified fuel cells are shown as ( ⁇ ).
  • Anode and cathode humidification temperatures are 70 and 65°C, respectively, for iron oxide loading of ⁇ 0.14 mg/cm 2 , and 75 and 70°C for loadings > to 0.20 mg/cm 2 .
  • Flow rates to the anode and cathode are 400 and 600 cc/minute, respectively.
  • These cells are H 2 /0 2 fuel cells operating at a pressure of one atmosphere (i.e., unpressurized cells). Only the cathode is magnetically modified in these experiments. Additional curves with cathode coatings of samarium cobalt magnets at 0.13 mg/cm 2 for 70°C are shown as (#). In Figure 3, similar data are shown except that curves of potential versus current are shown.
  • PEM fuel cells with only 0.14 mg/cm 2 of iron oxide magnets operating at 25°C produced more than 62% greater maximum current, and more than 70% greater maximum power, than nonmagnetic fuel cells operating at 70°C, where both sets of fuel cells are utilizing 1 atm of oxygen.
  • maximum current output i.e., 70°C, 0.35 mg/cm 2 of iron oxide magnets, for 1 atm of oxygen
  • maximum current and power densities are more than three times greater when the cathode is magnetically modified than when no magnetic loading is employed, with the peak value approximating 4.4 amps/cm 2 for maximum current, and 1.2 watts/cm 2 for maximum power, in the electrodes studied here.
  • the temperature coefficient for power density increases as iron oxide loading is increased up to 0.20 mg/cm 2 .
  • Table 3 shows the maximum current as a function of atmospheres of pressure of oxygen and magnetic loading of a cathode electrode.
  • Table 4 shows maximum power as a function of atmospheres of pressure of oxygen, as well as the effects of magnetic loading of the cathode for maximum current produced by these electrodes.
  • PEM fuel cells with magnetically modified cathodes operating at 1 atm of oxygen can produce more than twice the maximum current output of conventional PEM fuel cells that are fed oxygen at 3 atm; similarly, maximum power output is more than 80% greater at 1 atm with magnetic modification, compared to PEM fuel cells at 3 atm, but with no magnetic modification of cathodes.
  • magnetic modification produces results superior to prior art conventional, nonmagnetized cathodes.
  • the maximum power density for PEM fuel cells with iron oxide magnets loaded onto the cathode at 0.14 mg/cm 2 is 2.42 ⁇ 0.04 times that of PEM fuel cells that are nonmagnetic, and 3.5 ⁇ 0.1 times when the iron oxide loading is 0.20 mg/cm 2 .
  • the maximum current density is greater than 3 times higher for iron oxide loading at 0.20 mg/cm 2 over the entire temperature range, and greater than 2 times higher at 0.14 mg/cm 2 , compared to PEM fuel cells with nonmagnetically modified cathodes.
  • Flow rates for H 2 /0 2 are 400/600 cc/min for a 5 cm 2 cell;
  • Humidification temperatures for anode and cathode are 70-75 and 65-70°C
  • Flow rates for H 2 /0 2 are 400/600 cc/min for a 5 cm 2 cell; Humidification temperatures for anode and cathode are 70-75 and 65-70°C
  • Flow rates for H,/Air are 200/1400 cc/min for a 5 cm 2 cell; Humidification temperatures for anode and cathode are 70-75 and 65-70°C
  • Performance of nonmagnetic fuel cells is indicated as ( ⁇ ), and performance of cathode only magnetic modification is shown for 0.20 ( ⁇ ), 0.35 (O), and 0.40 (*) mg/cm 2 of iron oxide magnets.
  • Performance of fuel cells with both cathode and anode magnetic modification at 0.20 mg/cm 2 of iron oxide is indicated as ( A ).
  • the temperature is either 30 or 70°C, as indicated.
  • samarium cobalt magnets loaded at 0.13 mg/cm 2 operated between the values for iron oxide loaded at between 0.14 and 0.20 mg/cm 2 , except at temperatures ⁇ 50°C.
  • Hydrogen is oxidized at the anode of many fuel cells.
  • hydrocarbon fuels also may be oxidized, either direcdy (i.e., direct reformation) at the anode or indirecdy (i.e., indirect reformation), for example, by passing the fuel over a hot, copper and zinc catalyst to yield hydrogen.
  • direcdy i.e., direct reformation
  • indirecdy i.e., indirect reformation
  • the use of such hydrocarbon fuels may carry certain cost, power/mass, or other benefits, but the problem of passivation also is present in conventional fuel cell electrode systems due to the production of small amounts of carbon monoxide, a minor but highly potent catalyst poisoning byproduct of hydrocarbon oxidation.
  • the generated CO binds almost irreversibly to the noble metal catalyst, e.g., platinum.
  • Figure 18 depicts the general time course of current production for a PEM fuel cell operating at 70°C with only the cathode magnetically modified with 0.2 mg/cm 2 of iron oxide magnets and the anode not so coated ( ⁇ ), versus with cathode magnetically modified anode magnetically modified with 0.2 mg/cm 2 of iron oxide magnets (solid Hne). All electrodes are coated with 0.4 mg/cm 2 of platinum catalytic particles. When a flux of synthetic reformate is imposed on the anode, current density drops off dramatically and quickly when the anode is not magnetically modified.
  • Curves of potential versus current and power versus potential are shown in Figure 21.
  • Anode and cathode humidification temperatures were 75 and 70°C, respectively, and flow rates thereto were 400 and 600 cc/minute, respectively, for pure hydrogen and oxygen, magnetic modification of both cathode and anode, 0.20 mg/cm 2 of iron oxide magnets on the cathode and 0.20 to 0.40 mg/cm 2 on the anode (•); pure hydrogen, non-magnetic electrodes ( ⁇ ); pure hydrogen, 0.20 mg/cm 2 of iron oxide on both cathode and anode (A.); and reformate, cathode with 0.20 mg/cm 2 of iron oxide magnets, anode with 0.40 mg/cm 2 of iron oxide magnets (•) , both electrodes with 0.40 mg/cm 2 of platinum catalyst, cell temperature 70°C, anode temperature 90°C, and cathode humidification temperature 80°C.
  • cell conditions are 70° C cell temperature, 75 and 70° C cathode and anode temperature, 400 and 600 cc/min for anode and cathode, and Pt catalysts. Catalyst loadings are 0.4 mg/cm 2
  • the data for the fuel cell on reformate are somewhat suppressed compared to pure hydrogen, but not badly; the reduction may arise in part from the lower flow of reformate.
  • the maximum power density on hydrogen was 1.09 watts/cm 2 , and on reformate 0.96 watt/cm 2 .
  • the forward and back traces for the potential versus current density were superimposable, which is consistent with a stably operating fuel cell. For 0.8 volt, the current density was 0.18 amp/cm 2 ; for 0.8 amp/cm 2 , the voltage was 0.67 volt.
  • the classification of fuel cells based on choice of fuel includes hydrogen, indirect reformation, and direct reformation cells.
  • hydrogen/oxygen (H j /O j ) and hydrogen air (H 2 /air) cells pure hydrogen is fed into the anode and oxygen or air is fed into the cathode.
  • An indirect reformation fuel cell uses a fuel processor that converts a feedstock such as methanol and water to a mixture of hydrogen and carbon dioxide over a hot catalyst.
  • the fuel stream of hydrogen and carbon dioxide contains low level ( ⁇ 1 %) carbon monoxide.
  • Carbon monoxide fed into the anode rapidly passivates noble metal catalysts in low temperature systems without magnetic modification.
  • Direct reformation fuel cells would be the most convenient because they would operate by feeding a fuel such as methanol direcdy into the anode where it would be electrochemically converted to carbon dioxide and hydrogen ions.
  • Acetaldehyde is the first stable intermediate of ethanol oxidation. When ethanol undergoes electro-oxidation at an electrode surface, acetaldehyde and acetic acid are the major products. Ethanol loses two electrons to form acetaldehyde. Acetaldehyde, in turn, undergoes a two electron oxidation to form acetic acid.
  • the general reactions for ethanol and acetaldehyde oxidation are shown below, written as reduction potentials:
  • Acetaldehyde can undergo a disproportionation reaction to yield ethanol and acetic acid: 2 CH 3 CHO ⁇ CH 3 CH 2 OH + CH 3 COOH (20)
  • Equation 18 the overall cell potential (E° a/ ) of the reaction is + 0.32 volt.
  • Acetic acid is a product of ethanol and acetaldehyde oxidation, as is indicated in Equations 17 - 19. Acetic acid then undergoes oxidation to form methane, as follows (recall that equations are written here as reduction potentials): CH 3 * + C0 2 + - CH j COO ' (23)
  • the CH 3 * and the CH 3 COO * radicals can each combine with a respective H * radical from solution or other source to produce CH 4 and CH 3 COOH, respectively.
  • a carboxylic acid can undergo decarboxylation via a two electron oxidation to form a radical species in solution.
  • the radical species then tend to react either to form the corresponding alkane, or to undergo a one electron oxidation to form carbonium ions which can undergo further reaction.
  • Acetic acid oxidation can also produce other products, such as esters and acetals.
  • the particular composition of products for each of the above different combinations of reactants will depend on the individual reaction parameters, including such aspects as surface(s) of the electrodes, temperature, pH, oxidation state of the reaction solution, etc.
  • the oxidation of methanol proceeds through formaldehyde and formic acid. In the complete oxidation of methanol, formic acid would be converted to carbon dioxide.
  • the oxidation of ethanol proceeds through a similar sequence through acetaldehyde, acetic acid, methane, and methanol; the methanol sequence is the second half of ethanol oxidation.
  • the standard free energy per mole of formaldehyde is -72 kj, and K is 2 x 10 6 .
  • the disproportionation of formaldehyde is substantial for the normal range of conditions of operation of typical fuel cells, and contributes to the complications in interpreting/deducing reaction mechanisms.
  • voltammetric results for ethanol, acetaldehyde, and acetic acid indicate that passivation is suppressed at both magnetically and nonmagnetically modified electrodes.
  • electrical currents are larger, and the extent of conversion to products is higher, at magnetically modified electrodes, compared to nonmagnetically modified electrodes, including electrodes modified with Nafion®.
  • three figures of merit are utilized: the number of electrons transferred ( «), the current, and the current density. i. Number of electrons transferred, n.
  • Equation 17 each electrolysis step is formally separated by two electrons.
  • the complications of adsorption processes and facile interconversion(s) of any of the species in the sequence complicate interpretation of any voltammetric data pertaining thereto.
  • n is a rough estimate fo the extent of electrolysis.
  • Noninteger values of n are consistent with the partial oxidation of a species, and/or the mixed oxidation to several different species.
  • Cyclic voltametric data can be used to estimate, roughly, the number of electrons transferred , n, in the oxidation of each species. However, the estimated value of n more accurately provides a crude measure of reaction efficiency, than it does of electrons transferred because of the above discussed complications.
  • the value of n for each species was determined from the maximum peak current in the range between -0.200 and -0.500 volt vs. a standard calomel electrode. Results are summarized in Table 17 for different electrode modifications. The potential where the current peak was observed for each fuel is given as F oxidation'
  • magnetic modification provided approximately 32% more peak current as nonmagnetic modification for acetaldehyde, and approximately 2.6 fold for acetic acid.
  • Comparison for magnetically modified electrodes using acetic acid shows that the peak currents were about 5 fold higher than the peak currents for Nafion® modified electrodes. Peak current data' alone are insufficient for evaluating a given fuel for use in direct reformation in a PEM fuel cell.
  • acetaldehyde is a beneficial fuel for magnetically modified PEM fuel cells.
  • acetaldehyde improved current output by more than 50% over the current output for ethanol.
  • Acetic acid is also hkely to be a beneficial fuel, given its almost two-fold higher peak current output than ethanol, its lower cost than acetaldehyde, and its lesser irritant qualities.
  • the surface area of platinum (153 cm 2 for Nafion® /platinized carbon electrodes, and 113 cm 2 for Nafion® /magnets/platinized carbon electrodes) is higher than for the unmodified and Nafion® only modified electrodes (0.459 cm 2 ) because the platinum is distributed over the carbon black microparticles. If this platinum surface area is incorporated into the data of the composite modified electrodes, the efficiency of the Nafion® /magnets/platinized carbon electrodes is increased an additional 35% over the nonmagnetic modified electrodes.
  • FIGs 23 and 24 Graphical comparisons of the peak oxidation currents of ethanol, acetaldehyde, and acetic acid are shown in Figures 23 and 24.
  • values of peak current/concentration are shown for PEM magnetically modified fuel cells as a function of the square root of the scan rate. These data show that acetaldehyde exhibits higher oxidation efficiency than ethanol or acetic acid, and that acetic acid oxidation is more efficient than ethanol oxidation.
  • Figure 24 the data of Figure 23 are shown together with data for peak current/concentration for using acetaldehyde and acetic acid in the absence of magnetic modification of the electrodes. In each case (for acetaldehyde and for acetic acid), magnetic modification clearly improves oxidation efficiency.
  • I p /(A C 0 v' /2 ) is sensitive to the faradic current, where A is the surface area of the platinum catalyst, and C 0 is the substrate concentration in solution.
  • the quantity I p / ' (A C 0 v'' 2 ) is determined from the slope of a plot of I p /A C 0 versus v' 2 .
  • Table 19 summarizes data for the three substrates with magnetic and nonmagnetic composite electrodes.
  • the parameter l p f (A C 0 v' /2 ) provides a measure of the efficiency of charge transfer during the course of electrolysis.
  • acetaldehyde may provide a higher power density than acetic acid, owing to its roughly 17% lower molecular weight.
  • acetic acid may be predicted to have a lower cross over rate because the anionic sites of the ion exchange membrane would be expected to exclude the acetate ion.
  • Ruff equation is inefficient to accurately model the large and/or asymmetric potential shifts observed in our cyclic voltammetric studies of such redox couples as Ru(bpy) 3 +2 Ru(bpy) 3 +3 , where Ru refers to ruthenium, and bpy refers to bipyridyl.
  • Ru refers to ruthenium
  • bpy refers to bipyridyl.
  • peak potentials in 100 mV/second cyclic voltammograms shifted roughly 30mV lower in energy per unpaired electron in typical reactants.
  • all metal complex redox couples studied in magnetic composites on fuel cell electrodes showed a decrease in the difference between the cathodic and the anodic peak potentials.
  • the heterogeneous electron transfer rate constant of the metal redox couple complex in Nafion® under the influence of Earth's magnetic field was modeled using a finite difference one-dimensional computer simulation in which electron transfer rate constant, concentration of the redox couple, and apparent diffusion coefficient were the adjustable parameters.
  • the apparent coefficient was determined experimentally concetration is known from literature values. The simulation was used to determine k httm (1G). Equation 29 yields k hem (H). The same computer simulation protocol was then used to model the magnetic composite system, except that no adjustable parameters were employed.
  • the bulk concentration of the redox species in the magnetic composite was assumed to be the same as the bulk concentration in Nafion®.
  • the heterogeneous electron transfer rate constant for the magnetic composites was found to be well approximated by the heterogeneous electron transfer rate constant in the
  • Microparticles Magnetic (Polyscience) and superparamagnetic (Bangs Laboratories and Dynal) microparticles are a core of iron oxide shrouded with a thin, inert polymer layer. From electron micrographs, the diameters of Bangs beads/microparticles range from 0.5 to 2 ⁇ m, and Polyscience beads/microparticles are somewhat larger and more dispersed than the reported 1 to 2 ⁇ m. Dynal beads/microparticles are 4.5
  • Composites and Nafion® Film Preparation Films and composites were formed with a suspension (5% wt/vol) of the perfluorinated, sulfonic acid cation exchange polymer, Nafion® 1100 (Aldrich). Nafion® has hydrated and fluorocarbon phases. Glassy carbon electrodes (0.459 cm 2 ) were modified with either (a) a Nafion® film; (b) a composite of Nafion® and magnetic microparticles where the composite is formed under alignment from an external magnetic field; or (c) a composite of Nafion® and either magnetic or comparably sized nonmagnetic (Polyscience) microparticles formed without alignment. Electrodes were polished and cleaned as described previously (L.A.
  • Microscopy Composites were characterized by scanning electron microscopy (SEM - Hitachi S-2700 and S-4000) and magnetic force microscopy (MFM - Digital Instruments Nanoscape III), a technique analogous to atomic force microscopy but performed with a magnetic tip to map magnetic fields. From SEM images, aligned magnetic microparticles formed slightly conical pillars a few beads wide. From calculations, the field around a pillar decays to magnetic field of the earth (1-2 Gauss) at 20 ⁇ m; the observed interpillar separation of 40 ⁇ m is then consistent with pillar formation driven by interpillar repulsion. Nonmagnetic microparticles (Zook & Leddy, 1998) and unaligned magnetic microparticles cluster in composites. From MFM images, the field about magnetic microbeads in the composites is preserved in the absence of an externally applied field.
  • SEM scanning electron microscopy
  • MFM Magnetic force microscopy
  • Electrochemical Measurements Electrochemical flux through composites and films was probed with various redox species. Hexaaminerutheniurn (III) chloride (Alfa), potassium ferricyanide (Aldrich), and iron (III) perchlorate (Aldrich) were used as received.
  • Modified electrodes were equilibrated in solutions of the redox species and electrolyte for several hours prior to measurement.
  • a saturated calomel reference electrode (SCE) and large platinum mesh counter electrode completed the cell.
  • Data were collected and analyzed on 486 computers interfaced to either a Model 173 EG&G PARC Instruments Potentiostat/Galvanostat with a Model 276 interface module or a Cypress Systems Model CS-1090 Potentiostat. Scan rates ranged from 20 to 200 mV/second.
  • Ferricyanide anion was not electrolyzed through the composites and films, consistent with defect free modifying layers. Except as noted for superparamagnetic microparticle composites, electrochemical measurements were made in the absence of an external field.
  • R, T, n, F, A, and C* are the gas constant, temperature (K), number of electrons transferred, Faraday's constant, electrode area (cm 2 ), and redox probe concentration in the phase where diffusion occurs (moles/cm 3 ), respectively.
  • the porosity of the layer, E, is 1 for Nafion® films and the Nafion® volume fraction for the composites. Flux of species through the composites and films is parameterized by C* and D, where C* and D (cm 2 /second) are the same as in Equation 11. Equation 32 yields C*D 2 and given hterature or experimental values of C*, D' /2 is determined. Throughout, flux enhancements are reported for magnetic composites as compared to Nafion® films, and are expressed as the ratio of D 2 for the
  • the continuous wave EPR spectrometer (Bruker EMX61) was equipped with a variable temperature unit (Bruker ER4111). Nafion® suspension and paramagnetic redox probe were mixed to yield a film with an approximate concentration of 0.3 M. Films were rinsed and well dried. EPR measurements were made at 110 K.
  • Superparamagnetic Composites Superparamagnetic microparticles sustain a magnetic field only in an externally applied field. Superparamagnetic composites were cast either in an external field to form composites with aligned pillars of microparticles, or without the external field to form unaligned microparticle clusters. Unaligned composites resemble composites formed with nonmagnetic microparticles (Zook & Leddy, 1998). Cyclic voltarnrnetric measurements were made either inside the cylindrical magnet or not, such that the external magnetic field is either on or off during measurement. The redox probe was Ru(NH 3 ) 6 + ; composites contained
  • Flux enhancements for the aligned and unaligned composites measured in the field as compared to the aligned composites measured in the absence of the external field are
  • Ru(NH 3 ) 6 + was measured with an external field for the two composite electrodes and a
  • Nafion® film For the Nafion® film and the aligned composite where the microparticles did not contact the electrode surface, cyclic voltammograms were superimposed, consistent with no flux enhancement generated by the external field. For the composite where microparticles contacted the electrode, approximately 45% higher i p , was observed. The enhancement is slightly lower than for the Bangs microparticles because of lower microparticle content.
  • Self exchange a necessary step in the postulated mechanism for magnetic enchancement, is favored by high C* and slow D mr
  • concentrations are sufficiently high to support self exchange.
  • values of D m ,znd D Naf indicate that physical diffusion is sufficiently slow that self exchange in the magnetic field of earth (1 Gauss) enhances the a p p a r e n t di ffu s i o n c o e ffi c i e n t fo r th r e e o f t h e p r o b e s (Ru(NH, ⁇ + , Co(bpy)] + , and ) by 9 to 24%.
  • Flux enhancement through a self exchange process occurs whether the redox couple in solution is a radical or a singlet, because self exchange is sustained by both the radical and the singlet once voltammetry begins.
  • Co(bpy) 3 + are paramagnetic, and Ru(bpy) 3 + and Co(bpy) 3 + are diamagnetic (singlets);
  • Magnetic Effect Several observations are consistent with magnetically driven flux enhancements. From MFM images of composites, magnetic microparticles maintain their field in the absence of an externally apphed field. Flux of R (NH 3 ) 6 + through magnetic
  • the three trications exhibit flux enhancements of 1.16, 5.3, and 19.6, whereas the dication enhancements are 3.4 and 28.6. If MHD were a significant source of the flux enhancements, enhancements would be grouped by charge. Computer models of MHD effects on mass transport in magnetic composites generate flux enhancements of ⁇ 5% for the experimental conditions.
  • the proposed mechanism for the observed flux enhancement is augmentation of self exchange by the magnetic field.
  • the effect is characterized by the Dahms Ruff equation
  • Equation 11 where the magnetic field component is coupled through k l (H) as expressed in Equation 10.
  • H Prior work on nonmagnetic composites (Zook & Leddy, 1998; "Surface Diffusion in Microstructured Ion Exchange Matrices: Nafion/Neutron Track Etched Polycarbonate Membrane Composites,"/ Phys. Chem., 99(16) 6064-6073) has shown that the flux enhancement is largest at the Nafion®/microparticle interface; therefore, H is taken as the minimum field at the surface of the magnetic particle, 2100 Gauss. -4 tv (2100 Gauss) is calculated from C* as discussed above and the terms hsted in Table 20. The apparent diffusion coefficient in the magnetic composite is calculated and tabulated as D c ⁇ c . From Table 20, the modeled flux enhancement, . / ma8 - calc / ⁇ ls shown to agree well with the
  • the magnetic particles have an impact on the apparent diffusion coefficient.
  • the effect is smallest, in part, because D mt is large and C* is smaller.
  • the impact of the magnetic field is substantial, enhancing the apparent diffusion coefficient over that in Nafion® from 10 fold for to almost
  • the magnetic fuel cells of the instant invention have enhanced function due to magnetic facilitation of magnetically susceptible chemical reactions that otherwise are quantum mechanically forbidden or kinetically disfavored.
  • the magnetic fuel cells of the instant invention comprise an electrode system that includes a cathode, an anode, and a separator disposed between the anode and the cathode, as well as a magnetic field source adapted to produce a magnetic field in at least a portion of the electrode system.
  • the magnetic field source of the instant invention can comprise any magnetic field source, including an external magnet, an internal magnet, a microstructured magnetic composite material, both an external magnet and a microstructured magnetic composite material, and both an internal magnet and a microstructured magnetic composite material.
  • the magnetic field source may be a permanent magnet and/or an electromagnet. Permanent magnets may be macroscopic magnets, and/or microparticle magnets.
  • microparticle magnets may also be part of a composite and/or a microstructured (for example, pillared, etc.) composite material, for example, such as those disclosed in United States Patent Numbers 5,786,040, 5,817,221, 5,871,625, 5,928,804, 5,981 ,095, and 6,001 ,248 to Leddy, et al., which are hereby incorporated by reference in their respective entireties.
  • microstructured magnetic composite material it may be disposed on either the anode surface and/or the cathode surface, though best results occur when both are so magnetically modified.
  • the microstructured magnetic composite material may further comprise a first material having a first magnetism, a second material having a second magnetism, and an arrangement of said first and second materials to produce a plurahty of boundaries between the first and second materials, wherein each boundary is adapted to provide a plurahty of paths through the microstructured magnetic composite material, and has at least one magnetic field within at least one of the plurahty of paths.
  • the magnetic fuel cells of the instant invention which have enhanced function due to magnetic facilitation of a magnetically susceptible chemical reaction that otherwise is quantum mechanically forbidden or kinetically disfavored, may further comprise first and second chemicals, wherein each molecule of the first chemical has at least one electron having a plurahty of quantum mechanically allowed spin states, and each molecule of the second chemical has a nucleus susceptible to electron-nuclear spin polarization.
  • the interfacial boundary located respectively at each anode surface and each cathode surface, provides a region such that when 1) the magnetic field source is actuated to produce the magnetic field, 2) the magnetic field is effective at the interfacial boundary of the anode or the cathode, or of the cathode and the anode, and 3) the molecules of the first and second chemicals are within said effective magnetic field, then at least one electron of a molecule of the first chemical is polarized to another spin state, and the at least one spin polarized electron induces spin polarization of the nucleus of a molecule of the second chemical to effect transfer of at least one electron from one of said molecules of said first and second chemicals to the other molecule to effect said otherwise quantum mechanically forbidden or kinetically disfavored chemical reaction between molecules of said first and second chemicals.
  • the at least one electron of the molecule of the first chemical is polarized to another spin state, typically it is within about 10 nm of the interfacial boundary; i.e., within the magnetic field of the magnetic microparticles or other magnetic source.
  • electrons can be transferred to/ from electrode (original electrode surface or added composite surface) to the molecular or ion.
  • electrode surface original electrode surface or added composite surface
  • organic fuels are oxidized by a fuel cell
  • electrons are transferred to/ from electrode surface (original electrode surface or added composite surface) to organic molecule or ion.
  • the separator of the magnetic fuel cells of the instant invention typically is a proton exchange membrane (or PEM), which, for example, may be made of Nafion®, though other membranes and separators may be so employed without departing from the scope and spirit of the instant invention.
  • PEM proton exchange membrane
  • the current and power outputs for a fuel cell according to the instant invention with magnetic modification of the cathode, at about 0.35 mg/cm 2 of iron oxide magnets are at least about three times the current and power outputs of a comparable fuel cell that has no magnetically modified electrodes.
  • the current and power outputs when there is magnetic modification of both the cathode and anode, at about 0.20 mg/cm 2 of iron oxide magnets are at least about 3.5 times the current and power outputs of a comparable fuel cell that has no magnetically modified electrodes.
  • the enhanced rate of oxidation of the fuel that may occur also includes reaction products or reaction intermediates thereof, or combinations thereof, which are oxidized at the anode.
  • the fuel for practice of the instant invention is understood to be hydrogen, or any organic fuel including methanol, methane, formaldehyde, formic acid, and CO.
  • results for C, .4 organic compounds have been described herein, and may include such compounds as acetaldehyde, methanol, methane, formic acid, ethanol, ethane, acetic acid, isopropanol, n-propanol, propane, propionic acid, acetic anhydride, 1- butanol, 2-butanol, tertiary butanol, butanoic acid, or combinations thereof; however, any organic compound may be so employed in practice of the instant invention.
  • the rate of reduction of the oxidant that may be increased at the cathode is understood to include also reaction products or reaction intermediates of the oxidant(s).
  • any oxidant may be used in practice of the instant invention, including without limitation such oxidants as air, oxygen, a peroxide, or combinations thereof.
  • microparticle magnets When microparticle magnets are used, they may be made of iron oxide, samarium cobalt, neodymium iron baron, other magnetic materials or combinations thereof. When samarium cobalt microparticle magnets are used, they may be coated by a silanization process to enhance stability; and similar procedures can be used for other magnetic materials as well. Other magnetic materials may also be so coated. When microstructured magnetic composite material is used and it comprises iron oxide microparticles or other magnetic microparticles, then the microstructured magnetic composite material may be disposed on an electrode surface in an amount of up to at least about 0.50 mg per square centimeter. However, even higher composite material coatings of iron oxide magnets also fall within the spirit and scope of the instant invention. When samarium cobalt magnets are used in a microstructured magnetic composite material, coatings up to at least about 0.2 mg per square centimeter are possible.
  • the magnetic field source of the present invention can be any one or any combination of a plurahty of forms.
  • permanent microparticle magnets can be employed on the surface of an electrode.
  • non-permanent microparticles magnets for example, superparamagnetic magnets, such as nickel
  • an external magnetic field source that induces magnetic fields in the non-permanent magnets.
  • the ernbodirnent functions as long as the field of the permanent external magnet is within range; no net magnetic field is sustained once the external permanent magnet is removed.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Materials Engineering (AREA)
  • Inert Electrodes (AREA)

Abstract

Cellules électrochimiques magnétiques capables d'effectuer le reformage indirect d'un combustible organique, comprenant une cathode, une anode, un séparateur placé entre l'anode et la cathode, ainsi qu'une source de champ magnétique conçue pour produire un champ magnétique dans au moins une partie d'au moins une de ladite cathode et de ladite anode.
PCT/US2000/028242 1999-10-14 2000-10-13 Cellules electrochimiques modifiees magnetiquement WO2001028025A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU11985/01A AU1198501A (en) 1999-10-14 2000-10-13 Magnetically modified fuel cells

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US15937499P 1999-10-14 1999-10-14
US60/159,374 1999-10-14
US20832200P 2000-06-01 2000-06-01
US60/208,322 2000-06-01

Publications (1)

Publication Number Publication Date
WO2001028025A1 true WO2001028025A1 (fr) 2001-04-19

Family

ID=26855893

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/028242 WO2001028025A1 (fr) 1999-10-14 2000-10-13 Cellules electrochimiques modifiees magnetiquement

Country Status (2)

Country Link
AU (1) AU1198501A (fr)
WO (1) WO2001028025A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008142515A1 (fr) * 2007-05-18 2008-11-27 Toyota Jidosha Kabushiki Kaisha Catalyseur pour électrode de pile à combustible alcaline, et procédé de fabrication dudit catalyseur
CN110783588A (zh) * 2019-09-05 2020-02-11 浙江工业大学 一种燃料电池阳极的调控方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853628A (en) * 1973-07-26 1974-12-10 J Fox Fuel cell
US4037022A (en) * 1975-05-12 1977-07-19 Institut Francais Du Petrole Fuel cell
US5540981A (en) * 1994-05-31 1996-07-30 Rohm And Haas Company Inorganic-containing composites
US5928804A (en) * 1994-08-25 1999-07-27 The University Of Iowa Research Foundation Fuel cells incorporating magnetic composites having distinct flux properties
US6036838A (en) * 1997-11-15 2000-03-14 Deutsches Zentrum Fuer Luft -Und Raumfahrt E.V. Method for determining the substance conversion during electrochemical reactions and electrochemical unit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853628A (en) * 1973-07-26 1974-12-10 J Fox Fuel cell
US4037022A (en) * 1975-05-12 1977-07-19 Institut Francais Du Petrole Fuel cell
US5540981A (en) * 1994-05-31 1996-07-30 Rohm And Haas Company Inorganic-containing composites
US5928804A (en) * 1994-08-25 1999-07-27 The University Of Iowa Research Foundation Fuel cells incorporating magnetic composites having distinct flux properties
US6036838A (en) * 1997-11-15 2000-03-14 Deutsches Zentrum Fuer Luft -Und Raumfahrt E.V. Method for determining the substance conversion during electrochemical reactions and electrochemical unit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008142515A1 (fr) * 2007-05-18 2008-11-27 Toyota Jidosha Kabushiki Kaisha Catalyseur pour électrode de pile à combustible alcaline, et procédé de fabrication dudit catalyseur
CN110783588A (zh) * 2019-09-05 2020-02-11 浙江工业大学 一种燃料电池阳极的调控方法

Also Published As

Publication number Publication date
AU1198501A (en) 2001-04-23

Similar Documents

Publication Publication Date Title
US6355166B1 (en) Magnetically enhanced composite materials and methods for making and using the same
AU709505B2 (en) Gradient interface composites and methods therefor
Yang et al. Anion fluorine-doped La0. 6Sr0. 4Fe0. 8Ni0. 2O3− δ perovskite cathodes with enhanced electrocatalytic activity for solid oxide electrolysis cell direct CO2 electrolysis
US6479176B2 (en) Gradient interface magnetic composites and methods therefor
US5928804A (en) Fuel cells incorporating magnetic composites having distinct flux properties
CN104319410A (zh) 在燃料电池堆内维持不同电解质和气体压力的方法
US11268200B2 (en) Bipolar membranes
US10424804B2 (en) Optimization of the cerium-hydrogen redox flow cell
Bhattacharjee et al. Controlling oxygen-based electrochemical reactions through spin orientation
Bianchetti et al. Improving the oxygen evolution reaction on Fe3O4 (001) with single-atom catalysts
Lee et al. Water electrolysis and desalination using an AEM/CEM hybrid electrochemical system
Nechitailov et al. Mechanism of the effect of oxygen-modified carbon nanotubes on the kinetics of oxygen electroreduction on platinum
Xu et al. Magnetic field-enhanced oxygen evolution reaction via the tuneability of spin polarization in a half-metal catalyst
WO2001028025A1 (fr) Cellules electrochimiques modifiees magnetiquement
Panchenko Polymer electrolyte membrane degradation and oxygen reduction in fuel cells: an EPR and DFT investigation
Datta et al. Modeling of PEM Water Electrolyzer
Jing et al. Fabrication of copper-ceria hybrid composite electrode for electrocatalytic oxidation of methanol
Marquez et al. Structural Evolution of Ultrathin SrFeO3− δ Films during Oxygen Evolution Reaction Revealed by In Situ Electrochemical Stress Measurements
US20230264148A1 (en) Dissociation and recombination catalyst layers for reverse and forward-bias bipolar membranes
Shao Spin‐Dependent Metastable‐Phase Materials
Scholes Electronic processes in membranes
AU751125B2 (en) Gradient interface composites and methods therefor
Cavaliere Thermochemical Water Splitting Cycles
Wu et al. Controlled Surface Reconstruction on Ferromagnetic Oxides: Spin Pinning Effect to the Oxyhydroxide Layer and Its Enhanced Oxygen Evolution Activity
Gaonkar Third Row Transition Metal Compounds as Electrocatalysts for Water Oxidation in Basic Buffers

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP