WO2004107359A1 - Materiau carbone conducteur metallise a polymere greffe - Google Patents

Materiau carbone conducteur metallise a polymere greffe Download PDF

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Publication number
WO2004107359A1
WO2004107359A1 PCT/US2004/015567 US2004015567W WO2004107359A1 WO 2004107359 A1 WO2004107359 A1 WO 2004107359A1 US 2004015567 W US2004015567 W US 2004015567W WO 2004107359 A1 WO2004107359 A1 WO 2004107359A1
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Prior art keywords
conducting polymer
metal
carbonaceous material
carbon black
composition
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PCT/US2004/015567
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English (en)
Inventor
Srinivas Bollepalli
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Columbian Chemicals Company
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Priority claimed from US10/445,090 external-priority patent/US7175930B2/en
Priority claimed from US10/654,234 external-priority patent/US7195834B2/en
Application filed by Columbian Chemicals Company filed Critical Columbian Chemicals Company
Publication of WO2004107359A1 publication Critical patent/WO2004107359A1/fr

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    • 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
    • H01M4/90—Selection of catalytic material
    • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
    • 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
    • H01M4/92—Metals of platinum group
    • 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
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
    • 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
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • 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
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0234—Carbonaceous 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
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This invention relates generally to particulate conductive carbons.
  • the invention also relates to supported catalysts for fuel cells and proton exchange membranes.
  • a fuel cell is a device that converts energy of a chemical reaction into electrical energy (electrochemical device) without combustion.
  • a fuel cell (see e.g., Figure 1) generally comprises an anode 20, cathode 50, electrolyte 10, backing layers 30, 60, and flow fields/current collectors 40, 70. There are five types of fuel cells, as defined by their electrolytes:
  • a polymer electrolyte membrane fuel cell comprises a proton conductive polymer membrane electrolyte 10 sandwiched between electrocatalysts (a cathode 50 and an anode 20) (see, e.g., Figure 1).
  • the oxidation and reduction reactions occurring within the fuel cell are:
  • Fuel cells are a clean, low emission, highly efficient source of energy. Fuel cells can have 2-3 times greater efficiency than internal combustion engines and can use abundant and/or renewable fuels. Fuel cells produce electricity, water, and heat using fuel 90 and oxygen 80. Water (liquid and vapor) is the only emission when hydrogen is the fuel.
  • a catalyst 56 facilitates the separation of the hydrogen gas fuel into electrons and protons (hydrogen ions).
  • the hydrogen ions pass through the membrane 10 (center of fuel cell) and, again with the help of the catalyst 56, combine with an oxidant 80, such as oxygen, and electrons on the cathode side, producing water.
  • the electrons, which cannot pass through the membrane 10, flow from the anode 20 to the cathode 50 through an external circuit containing a motor or other electrical load, which consumes the power generated by the cell.
  • a catalyst 56 is used to induce the desired electrochemical reactions at the electrodes 20, 50.
  • the catalyst 56 is often incorporated at the electrode/electrolyte interface by coating a slurry of the electrocatalyst particles 56 to the electrolyte 10 surface.
  • electrochemical reaction occurs, generating protons and electrons.
  • the electrically conductive anode 20 is connected to an external circuit, which carries electrons by producing electric current.
  • the polymer electrolyte 10 is typically a proton conductor, and protons generated at the anode catalyst migrate through the electrolyte 10 to the cathode 50. At the cathode catalyst interface, the protons combine with electrons and oxygen to give water.
  • the catalyst 56 is typically a particulate metal such as platinum and is dispersed on a high surface area electronically conductive support 52.
  • the electronically conductive support material 52 in the PEMFC typically consists of carbon particles. Carbon has an electrical conductivity (10 "1 - 10 “2 S/cm) which helps facilitate the passage of electrons from the catalyst 56 to the external circuit. Proton conductive materials 54 such as National® are often added to facilitate transfer of the protons from the catalyst 56 to the membrane interface.
  • the fuel cells are operated under humidified conditions.
  • hydrogen fuel 90 and oxygen 80 gases are humidified prior to entry into the fuel cell.
  • carbon is relatively hydrophobic, and as such, the boundary contact between the reactive gases, water and the surface of the solid electrodes made of carbon contributes to high electrical contact resistance and ohmic power loss in the fuel cell resulting in lower efficiency of the fuel cell.
  • the hetero atom-containing conductive polymer-grafted carbon material shows hydrophilic character and thereby enhances the humidification process. Also, the higher electronic conductivity of these polymers facilitates the electron transfer process.
  • An ordinary electrolyte is a substance that dissociates into positively charged and negatively charged ions in the presence of water, thereby making the water solution electrically conducting.
  • the electrolyte in a PEM fuel cell is a polymer membrane 10.
  • the membrane material e.g., National®
  • Polymer electrolyte membranes 10 are somewhat unusual electrolytes in that, in the presence of water, which the membrane 10 readily absorbs, the negative ions are readily held within their structure. Only the protons contained within the membrane 10 are mobile and free to carry positive charge through the membrane 10. Without this movement within the cell, the circuit remains open and no current would flow.
  • Polymer electrolyte membranes 10 can be relatively strong, stable substances. These membranes 10 can also be effective gas separators. Although ionic conductors, PEM do not conduct electrons. The organic nature of the structure makes it an electronic insulator. Since the electrons cannot move through the membrane 10, the electrons produced at one side of the cell must travel through an external circuit to the other side of the cell to complete the circuit. It is during this external route that the electrons provide electrical power.
  • a polymer electrolyte membrane 10 can be a solid, organic polymer, usually poly(perfluorosulfonic) acid.
  • a typical membrane material, National ®, consists of three regions:
  • the negative ions, SO " are permanently attached to the side chain and cannot move.
  • the hydrogen ions become mobile. Ion movement occurs by protons, bonded to water molecules, migrating from SO 3 " site to SO 3 " site within the membrane. Because of this mechanism, the solid hydrated electrolyte is a good conductor of hydrogen ions.
  • the catalyst support 52 serves to conduct electrons and protons and to anchor the catalyst 56 (e.g., noble metal). Many efforts have been aimed at lowering the costs of fuel cells by lowering noble metal (e.g., platinum) catalyst 56 levels due to noble metal's cost. One way to lower this cost is to construct the catalyst support layer 52 with the highest possible surface area.
  • the electrodes 20, 50 of a fuel cell typically consist of carbon 52 onto which very small metal particles 56 are dispersed.
  • the electrode is somewhat porous so that gases can diffuse through each electrode to reach the catalyst 56.
  • Both metal 56 and carbon 52 conduct electrons well, so electrons are able to move freely through the electrode.
  • the small size of the metal particles 56 about 2 nm in diameter for noble metal, results in a large total surface area of metal 56 that is accessible to gas molecules. The total surface area is very large even when the total mass of metal 56 is small. This high dispersion of the catalyst 56 is one factor to generating adequate electron flow (current) in a fuel cell.
  • Conducting polymers are a class of conjugated double bond polymers whose electrical conductivities are comparable to the conductivities of semiconductors to metals, in the range of 0.1 to 100 S/cm.
  • Typical examples of conducting polymers include polyaniline, polypyrrole, polythiophene, polyfuran, and polyphenylene.
  • Both polyaniline and polypyrrole catalyst support 52 materials have shown improved fuel cell efficiency (e.g., U.S. 5,334,292 and WO 01/15253). However, the long-term stability of these materials has not been demonstrated in electrode environments in cyclic operations. Conducting polymers alone used as catalyst support 52 material have higher costs, lower surface area, and lower stability compared to those supports 52 based on carbon.
  • a conducting polymer is grafted onto the surface of a carbonaceous material thereby increasing the electrical conductivity of the carbonaceous material, and the stability of the hybrid material is expected to be enhanced.
  • the polymer grafting process also reduces the porosity of the carbon support, resulting in increased metal availability for electrode reaction.
  • the majority of the cost associated with electrodes is attributed to the high cost of the metal, which makes up the catalyst 56. Only those catalytic sites exposed on the surface of the catalytic particles contribute to the catalytic activity of the electrode and, thus, electrodes with the highest fraction of the metals accessible to the reaction should be the most effective. Carbon supports 52 with high porosity result in "trapped" metal sites that are not accessible for electrode reaction.
  • the extent of dispersion of the metal catalyst 56 on the support material 52 and the stability of such high dispersion in use, i.e., resistance of the catalyst against sintering and/or agglomeration, is directly related to the surface area and the availability of surface sites on which the dispersed metal 56 can be anchored.
  • the conducting polymer-grafted carbon material aids the uniform dispersion and stabilization of metal particles by anchoring to hetero atoms, namely, N, O, S, etc., present in the conducting polymer.
  • hetero atom- containing anchoring groups resist the agglomeration and sintering of metal (e.g., platinum (Pt)) crystallite particles.
  • the present invention provides a PEMFC electrode which can be made more cost-effective than electrodes having exclusively carbon support or exclusively conducting polymer support. For the above reasons, improvement of the supported catalyst is desired and has been achieved with the present invention.
  • this invention in one aspect, relates to conductive polymer-grafted carbons.
  • the invention includes a composition comprising a particulate carbonaceous material, and a conducting polymer containing hetero atoms wherein the conducting polymer is grafted onto the carbonaceous material.
  • the composition further comprises a metal.
  • the invention also includes a method for preparing a carbon with enhanced electronic conductivity comprising oxidatively polymerizing monomer of a conducting polymer containing hetero atoms with particulate carbonaceous material to form a conducting polymer-grafted carbonaceous material. The oxidative polymerization can take place using metal-containing oxidizing agent.
  • a device comprising a particulate carbonaceous material, and a conducting polymer containing hetero atoms, wherein the conducting polymer is grafted onto the carbonaceous material.
  • the device can further comprise a metal.
  • a fuel cell comprising an anode, a cathode, and a PEM is further included.
  • This invention relates to a process of grafting conducting polymers containing hetero atoms onto particulate carbon material (e.g., carbon black, graphite, nanocarbons, fullerenes, finely divided carbon or mixtures thereof) by in situ polymerization and the compositions resulting therefrom.
  • the conducting polymers are, for example, polyaniline and polypyrrole.
  • This invention relates to the application of conducting polymer-grafted carbons in fuel cell applications.
  • This invention particularly relates to the application of conducting polymer-grafted carbons as support material in fuel cell catalysts.
  • the invention further relates to a process of grafting conducting polymers containing hetero atoms onto particulate carbon material essentially simultaneously with metallizing the composition.
  • Figure 1 shows a "typical" PEMFC.
  • Figure 1 A shows a schematic drawing of PEMFC.
  • Figure IB shows a close up of an electrode and membrane of the PEMFC.
  • Figure 2 is an X-ray photoelectron survey spectrum (XPS) of the polyaniline- grafted carbon black of Example 1. This figure shows the presence of the Nls peak which supports that polyaniline has indeed been grafted to the carbon black surface.
  • Figure 3 is an X-ray photoelectron survey spectrum (XPS) of the polypyrrole- grafted carbon black of Example 3. This figure shows the presence of the Nls peak which supports that polypyrrole has indeed been grafted to the carbon black surface.
  • Figure 4 is an X-ray photoelectron survey spectrum (XPS) of 20% Pt/polyaniline-grafted carbon black of Example 4. This figure shows the presence of the Pt4f peak wliich supports that polyaniline-grafted carbon black has been platinized.
  • Figure 5 is an X-ray photoelectron survey spectrum (XPS) of 20% Pt/polypyrrole-grafted carbon black of Example 6. This figure shows the presence of the Pt4f peak which supports that polypyrrole-grafted carbon black has been platinized.
  • Figure 6 is an X-ray photoelectron survey spectrum (XPS) of 20%
  • FIG. 7 is a photomicrograph (TEM) of a commercial catalyst (20%Pt/XC72), A, versus a catalyst of the present invention (20%Pt/polyaniline grafted CDX-975), B.
  • the TEM shows the better Pt dispersion on the polyaniline-grafted CDX-975.
  • Figure 8 is a photomicrograph (TEM) of platinized and polypyrrole-grafted CDX-975 from Example 8.
  • Figure 8 A is on a 50 nm scale.
  • Figure 8B is on a 10 nm scale.
  • Anode humidification bottle temperature 105°C
  • Cathode humidification bottle temperature 90°C.
  • Reactant gases: Anode hydrogen 60 ml/min + 14 ml/min/A
  • Cathode oxygen 60 ml/min + 8 ml/min/A
  • Anode humidification bottle temperature 105°C
  • Cathode humidification bottle temperature 90°C.
  • Anode hydrogen 60 ml/min + 14 ml/min/A
  • Cathode oxygen 60 ml min + 8 ml/min/A
  • Ranges may be expressed herein as from “about” one particular value, and/or to "about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
  • X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.
  • a weight percent of a component is based on the total weight of the formulation or composition in which the component is included.
  • an effective amount of a composition or property as provided herein is meant such amount as is capable of performing the function of the composition or property for which an effective amount is expressed.
  • the exact amount required will vary from process to process, depending on recognized variables such as the compositions employed and the processing conditions observed. Thus, it is not possible to specify an exact "effective amount.” However, an appropriate effective amount may be determined by one of ordinary skill in the art using only routine experimentation.
  • substituted conducting polymer is used herein to describe any chemical variation to a conducting polymer that retains the functionalities of conductivity and hetero atoms.
  • poly-3 -methyl-aniline is a "substituted" polyaniline.
  • FC Fluel cell
  • SOFC solid oxide
  • MCFC molten carbonate
  • AFC alkaline
  • PAFC phosphoric acid
  • PEM PEM
  • DMFC direct methanol
  • a “proton exchange membrane” is also known or referred to as polymer electrolyte membrane, solid polymer membrane (SPM), or solid polymer electrolyte (SPE) in the fuel cell art.
  • PEMFC is a type of fuel cell that utilizes a polymer electrolyte membrane to carry protons between two catalytic electrode layers, thus generating electrical current.
  • a PEM typically operates at temperatures up to 100 °C.
  • MEA Membrane electrode assembly
  • Metal as used herein can be, e.g., a precious metal, noble metal, platinum group metals, platinum, alloys and oxides of same, and compositions that include transition metals and oxides of same. As used herein, it is a “metal” that acts as a catalyst for the reactions occurring in the fuel cell.
  • the metal may be tolerant of CO contaminants and may also be used in direct methanol fuel cells.
  • Ionomer is an ionically conductive polymer (e.g., National®). An ionomer is also frequently used in the electrode layer to improve ionic conductivity.
  • Membrane can be known as polymer electrolyte membrane, solid polymer electrolyte, proton exchange membrane, separator, or polymer membrane.
  • the “membrane” is an ionically conductive, dielectric material against which catalytic electrodes are placed or affixed.
  • the membrane most frequently used is a perfluorosulfonated polymer (e.g., Nation®), which can be obtained in varying thicknesses, equivalent weights, etc.
  • Electrode as used herein is a nonmetallic electric conductor in which current is carried by the movement of ions or a substance that when dissolved in a suitable solvent becomes an ionic conductor.
  • the polymer membrane of a fuel cell is the electrolyte.
  • Electrode also referred to as a “catalyst,” is a metal (as defined above) which is catalytic for fuel cell reactions, typically supported on a catalyst support (defined below).
  • “Supported catalyst” is a metal (as defined above) dispersed on a support.
  • Catalyst support is a material upon which metal (as defined above) is dispersed, typically conductive (e.g., carbon black, conducting polymer, or modified carbon black).
  • Electrode is the layer of supported electrocatalyst in contact with and/or affixed to a membrane.
  • the electrode may include ionomer and other materials in addition to the electrocatalyst.
  • Oxygen reduction reaction also known as ORR, cathode reaction, or cathodic process, is a reaction in which oxygen gas is reduced in the presence of protons, producing water.
  • Haldrogen oxidation reaction is also known as HOR, anode reaction, or anodic process. This is a reaction in which hydrogen gas is converted into protons and electrons.
  • Cathode is the electrode where oxidant reduction reaction occurs.
  • Gas diffusion layer is a layer adjacent to the electrodes which aides in diffusion of gaseous reactants across the electrode surface; it is typically a carbon cloth or carbon-based/carbon-containing paper (e.g., one manufactured by Toray).
  • the GDL should be electrically conductive to carry electrons through an external circuit.
  • “Current collector” is the portion of a fuel cell adjacent to the GDL through which electrons pass to an external circuit; it may also contain channels or paths (flow field) to assist in gas distribution and is typically made of graphite or conductive composites.
  • Flow field is the scheme for distributing gaseous reactants across the electrode.
  • a flow field may be part of a current collector and/or a GDL.
  • Insulator or dielectric, is a material which is not electrically conductive.
  • Electrode conductivity is the ability of a material to conduct electrons.
  • Protonic conductivity or ionic conductivity (IC) is the ability of a material to conduct ions or protons.
  • platinization or more generically, “metallization,” is a process of depositing or precipitating metal (as defined above) onto the surface of a catalyst support. Specifically, platinization is a process of depositing or precipitating platinum (Pt) onto the surface of a catalyst support.
  • Metal-containing oxidizing agent refers to an oxidizing agent containing metal in an oxidized form (higher oxidation state) wherein the metal-containing oxidizing agent is capable of effecting oxidative polymerization of a monomer with concurrent reduction of the metal.
  • Carbon black is a conductive acmoform carbon utilized, for example, as a catalyst support (defined above).
  • Portion or permeability, can be used to refer to porosity of carbon black (i.e., difference in NSA and STS A surface area measurements), or to macroscopic porosity of an electrode structure (i.e., related to ability of diffusion of gaseous reactants through an electrode layer).
  • Carbonaceous refers to a solid material comprised substantially of elemental carbon.
  • Carbonaceous material is intended to include, without limitation, i) carbonaceous compounds having a single definable structure; or ii) aggregates of carbonaceous particles, wherein the aggregate does not necessarily have a unitary, repeating, and/or definable structure or degree of aggregation.
  • Porate means a material of separate particles.
  • Polyization curve IV curve, or current- oltage curve, is the data/results from electrochemical analysis of MEAs or catalyst materials.
  • PANI polyaniline
  • PY polypyrrole
  • X-ray diffraction is an analysis method for determining crystallographic properties of a material, specifically as used herein the size of dispersed metal particles.
  • X-ray photoelectron spectroscopy (XPS), or electron scanning chemical analysis (ESC A) is an analysis method for obtaining chemical state information on materials.
  • CO chemisorption or more simply, CO, is an analysis method for determining the available surface area of a material, specifically metal particles.
  • the present invention provides a method of grafting conducting polymers, specifically conducting polymers containing hetero atoms, on a particulate carbon substrate and the resulting composition.
  • the conducting polymer-grafted carbon serves as unique catalyst support to increase the electronic conductivity and uniform distribution of metal particles in fuel cell supported catalysts.
  • the invention includes a composition comprising a particulate carbonaceous material (substrate), and a conducting polymer containing hetero atoms, wherein the conducting polymer is grafted onto the surface of the carbonaceous material.
  • the composition can further comprise a metal.
  • the carbonaceous material is described below.
  • the carbonaceous material can be less than about 98% by weight of the composition of the present invention, for example, about 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, or 97%.
  • the carbonaceous material can be about 1% to about 90% by weight of the composition, for example, about 2, 5, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, or 88%.
  • the carbonaceous material can be about 40% to about 90% by weight of the composition, for example, about 41, 44, 46, 50, 51, 54, 56, 60, 61, 64, 66, 70, 71, 74, 76, 80, 81, 84, 86, or 89%>.
  • the carbonaceous material can be about 50% to about 80% by weight of the composition, for example, about 53, 54, 55, 57, 58, 60, 63, 65, 67, 68, 70, 73, 75, 77, 78, or 79%>, of the present invention.
  • the conducting polymer is described below.
  • the conducting polymer can be greater than about 0% and less than about 100% by weight of the composition of the present invention, for example, about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or 99%.
  • the conducting polymer can be about 1% to about 50% by weight, for example, 2, 5, 7, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 48, or 49%.
  • the conducting polymer can be about 20% to about 50% by weight, for example, about 22, 24, 25, 30, 35, 40, 45, 47, or 48%, of the composition of the present invention.
  • the conducting polymer contains hetero atoms which are also described below.
  • the conducting polymer containing hetero atoms is grafted onto the surface of the carbonaceous material.
  • the conducting polymer can be grafted to the carbonaceous material, for example, by a method described below.
  • the conducting polymers can be formed and grafted to the carbonaceous material, for example, by oxidatively polymerizing a monomer of the conducting polymer with the carbonaceous material.
  • the composition can further comprise a metal.
  • the metal is described below.
  • the metal can be about 2% to about 80%) of the composition, for example, about 3, 5, 7, 8, 10, 12, 13, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, or 78%.
  • the metal can be about 2% to about 60% of the composition, for example, about 5, 7, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 57%.
  • the metal can be about 20% to about 40% of the composition for example, about 22, 25, 30, 35, or 38%.
  • the metal can be uniformly distributed "through" the composition, i.e., on the surface of the composition or in the conducting polymer of the composition.
  • the carbonaceous material can be any particulate, substantially carbonaceous material that is an electronically conductive carbon and has a "reasonably high" surface area.
  • carbon black, graphite, nanocarbons, fullerenes, fullerenic material, finely divided carbon, or mixtures thereof can be used.
  • the carbonaceous material can be carbon black.
  • the choice of carbon black in the invention is not critical. Any carbon black can be used in the invention. Carbon blacks with surface areas (nitrogen surface area, NSA) of about 200 to about 1000 m 2 /g, for example, 200, 220, 240, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, or 950 m 2 /g can be used. Specifically, a carbon black with a surface area of 240 m 2 /g (NSA, ASTM D6556) can be used. It is preferred that the carbon black have fineness effective for metal dispersion. It is preferred that the carbon black have structure effective for gas diffusion.
  • NSA nitrogen surface area
  • the carbon black can be less than about 98%> by weight of the composition of the present invention, for example, about 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, or 97%.
  • the carbon black can be about 1% to about 90% by weight of the composition, for example, about 2, 5, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, or 88%.
  • the carbon black can be about 40% to about 90% by weight of the composition, for example, about 41, 44, 46, 50, 51, 54, 56, 60, 61, 64, 66, 70, 71, 74,
  • the carbon black can be about 50% to about 80% by weight of the composition, for example, about 53, 54, 55, 57, 58, 60, 63, 65, 67, 68, 70, 73, 75,
  • carbon black particles have physical and electrical conductivity properties which are primarily determined by the particle and aggregate size, aggregate shape, degree of graphitic order, and surface chemistry of the particle. Also, the conductivity of highly crystalline or highly graphitic particles is higher than the conductivity of more amorphous particles. Generally, any of the forms of carbon black particles is suitable in the practice of the present invention and the particular choice of size, structure, and degree of grapl itic order depends upon the physical and conductivity requirements of the carbon black.
  • Carbon blacks are commercially available (e.g., Columbian Chemical Company, Atlanta, GA). Other Carbonaceous Material
  • the particulate carbonaceous material can be a material other than carbon black.
  • the choice of other carbonaceous material in the invention is not critical. Any substantially carbonaceous material that is an electronically conductive carbon and has a "reasonably high" surface area can be used in the invention.
  • graphite, nanocarbons, fuUerenes, fuUerenic material, finely divided carbon, or mixtures thereof can be used.
  • the carbonaceous material have fineness effective for metal dispersion. It is preferred that the carbonaceous material have structure effective for gas diffusion.
  • One of skill in the art could readily choose a carbonaceous material for a particular application.
  • the carbonaceous material can be less than about 98%) by weight of the composition of the present invention, for example, about 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, or 97%.
  • the carbonaceous material can be about 1% to about 90%> by weight of the composition, for example, about 2, 5, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, or 88%.
  • the carbonaceous material can be about 40% to about 90% by weight of the composition, for example, about 41, 44, 46, 50, 51, 54, 56, 60, 61, 64, 66, 70, 71, 74, 76, 80, 81, 84, 86, or 89%.
  • the carbonaceous material can be about 50%) to about 80% by weight of the composition, for example, about 53, 54, 55, 57, 58, 60, 63, 65, 67, 68, 70, 73, 75, 77, 78, or 79%, of the present invention.
  • the conductive material used in the invention is any conductive material which is effective for the discussed purposes of the invention.
  • the conductive material can be a conducting polymer.
  • the conducting polymer can be any organic polymer capable of electronic conductivity attributable to extended conjugated/delocalized multiple bonds and containing unshared electron pairs as provided by die presence of hetero atoms.
  • Polyaniline, polypyrrole, polythiophene, polyfuran, poly(p-phenylene-oxide), poly(p-phenylene-sulfide), substituted conducting polymers, or mixtures thereof can be used.
  • the conducting polymer can include polyaniline, polypyrrole, polyfuran, polythiophene, or mixtures thereof. Mixtures of these polymers can include physical mixtures as well as copolymers of the monomers of the respective polymers.
  • the conducting polymer can comprise polyaniline or polypyrrole.
  • the conducting polymer is grafted to the carbonaceous material surface in a process such as oxidative polymerization.
  • the monomer(s) of the desired resulting conducting polymer is polymerized in the presence of the carbonaceous material, thus grafting the polymer to the carbonaceous material. A method for making this is described below.
  • the presence of polymers in the final composition is supported by XPS results and by the observed physical properties (e.g., ability to press films from the composition).
  • a conductive material e.g., conducting polymer
  • Conducting polymers are commercially available and are readily prepared by a person of ordinary skill in the art.
  • the conducting polymer contains hetero atoms.
  • the hetero atoms can be N, S, and O, for example.
  • the amount of hetero atoms in weight % of the resulting polymer is the same weight %> as the hetero atoms in the monomer(s) used for the polymer (e.g.,
  • the location of the hetero atoms in the conducting polymer also depends on the corresponding monomer(s).
  • the conducting polymer with hetero atoms is grafted onto the carbon black surface, for example, thereby increasing the electrical conductivity of the carbonaceous material and the stability of the hybrid (i.e., polymer + carbon) material is expected to be enhanced.
  • the polymer grafting process also reduces the porosity of the carbon black.
  • the hetero atom containing conductive polymer-grafted carbon material also shows hydrophilic character and thereby enhances the humidification process when used in a fuel cell application, for example. Also, the higher conductivity of these polymers facilitates the electron transfer process.
  • the conducting polymer can be greater than about 0%> and less than about 100% by weight of the composition of the present invention, for example, about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or 99%.
  • the conducting polymer can be about 1% to about 50% by weight, for example, 2, 5, 7, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 48, or 49%.
  • the conducting polymer can be about 20% to about 50% by weight, for example, about 22, 24, 25, 30, 35, 40, 45, 47, or 48%», of the composition of the present invention.
  • the grafted conducting polymer (with hetero atoms) grafted on carbonaceous material behaves differently, when used as a catalyst support, than the carbonaceous material alone or the conducting polymer alone.
  • a composition of the present invention can be utilized as a catalyst support.
  • a catalyst support of the present invention comprises a carbonaceous material and a conductive material (e.g., a conducting polymer containing hetero atoms). The conductive material is grafted to the carbonaceous material thus forming a single material rather than merely a mixture.
  • the catalyst support comprises the conducting polymer-grafted carbonaceous material. The amount of each component is described above.
  • a composition of the present invention can further comprise a metal.
  • the metal can be, for example, platinum, iridium, osmium, rhenium, ruthenium, rhodium, palladium, vanadium, chromium, or a mixture thereof, or an alloy thereof, specifically, the metal can be platinum.
  • the metal can also be alloys or oxides of metals effective as catalysts.
  • the form and/or size of the metal provide the highest surface area of the metal possible per unit mass. It is desired that the size of the metal particles be kept as small as possible to achieve this end. Generally, in the art, metal particles end up as approximately 2 to about 6 nm during use in fuel cells due to sintering. A size less than about 2 nm can provide better performance. Atomic platinum, for example, would be ideal and found in groups of about 3 atoms.
  • the amount of metal can be any amount.
  • the amount of metal can be an effective catalytic amount. One of skill in the art can determine an amount effective for the desired performance.
  • the metal can be about 2% to about 80% of the composition, for example, about 3, 5, 7, 8, 10, 12, 13, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, or 78%.
  • the metal can be about 2% to about 60% of the composition, for example, about 5, 7, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 51%.
  • the metal can be about 20% to about 40% of the composition for example, about 22, 25, 30, 35, or 38%>.
  • the metal can be uniformly distributed "through" the composition, i.e., on the surface of the composition or in the conducting polymer of the composition. One of skill in the art could readily choose which metal to use in the composition for a particular application. Metals are commercially available. SUPPORTED CATALYST/ELECTRODE
  • the catalyst support above can further comprise a metal.
  • This resulting composition can be a supported catalyst (or electrode), such as in a fuel cell.
  • the catalyst support and metal are described above.
  • the metal can be uniformly distributed "through" the catalyst support.
  • the supported catalyst can be made by methods described below.
  • the supported catalyst can be made by grafting a conducting polymer containing hetero atoms to a particulate carbonaceous material and then adding the metal.
  • the conducting polymer containing hetero atoms can be formed and grafted to carbonaceous material (e.g., carbon black) by oxidative polymerization of the monomer of the conducting polymer in the presence of the carbonaceous material and then subsequently metallized (e.g., platinized).
  • the supported catalyst can be made and metallized essentially simultaneously by forming and grafting the conducting polymer containing hetero atoms to carbonaceous material (e.g., carbon black) by oxidative polymerization of the monomer of the conducting polymer in the presence of the carbonaceous material and a metal-containing oxidizing agent.
  • carbonaceous material e.g., carbon black
  • the supported catalyst can be used in various applications requiring such a supported catalyst.
  • One example of such an application is in a fuel cell, specifically as an electrode in a fuel cell.
  • the conducting polymer-grafted carbon black aids the uniform dispersion of metal such as by anchoring the metal to the hetero atoms present in the conducting polymer.
  • the hetero atom-containing anchoring groups facilitate prevention of agglomeration and sintering of platinum (Pt) (or other metal) particles.
  • the conducting polymer is grafted on the carbon black surface, for example, thereby increasing the electrical conductivity of the carbonaceous material and the stability of the hybrid material is expected to be enhanced.
  • the reduction in available porosity of the carbon black due to the polymer grafting process results in increased metal accessability for the electrode reaction.
  • Examples 16 and 17 below show a comparison of the dispersion of Pt on carbon black in the supported catalysts of the present invention relative to a HiSPECTM supported catalyst.
  • the invention includes various devices. ELECTRODE
  • An electrode of the present invention is described above.
  • An electrode of the invention can serve as either an anode, a cathode, or both.
  • MEA membrane/electrode assembly
  • the supported catalyst/electrode material is first prepared in liquid “ink” form by thoroughly mixing together appropriate amounts of supported catalyst (powder of metal, e.g., Pt, dispersed on carbon) and a solution of the membrane material (ionomer) dissolved in a solvent, e.g., alcohols.
  • a solvent e.g., alcohols.
  • the "ink” is prepared, it is applied to the surface of the solid membrane, e.g., Nafion®, in a number of different ways.
  • the simplest method involves painting the catalyst "ink” directly onto a dry, solid piece of membrane. The wet supported catalyst layer and the membrane are heated until the catalyst layer is dry.
  • the membrane is then turned over and the procedure is repeated on the other side. Supported catalyst layers are then on both sides of the membrane.
  • the dry membrane/electrode assembly is next rehydrated by immersing in dilute acid solution to also ensure that the membrane is in the H + form needed for fuel cell operation.
  • the final step is the thorough rinsing in distilled water.
  • the membrane/electrode assembly is then ready for insertion into the fuel cell hardware.
  • the membrane/electrode assembly can have a total thickness of about 200 ⁇ m, for example, and conventionally generate more than 0.5 an ampere of current for every square cm of membrane/electrode assembly at a voltage between the cathode and anode of 0.7 V, when encased within well-engineered components.
  • the supported catalyst/electrode of the present invention is described above.
  • the supported catalyst/electrode can be applied to the membrane of the MEA which is described below.
  • the supported catalyst can be added to a solvent and "painted" onto the membrane.
  • One of skill in the art could easily determine methods for applying the supported catalyst to the membrane.
  • Transfer Membrane/Electrolyte The PEM carries the necessary protons from the anode to the cathode while keeping the gases safely separate.
  • the thickness of the membrane in a membrane/electrode assembly can vary with the type of membrane.
  • the thickness of the supported catalyst layers depends on how much metal is used in each electrode. For example, for supported catalyst layers containing about 0.15 mg Pt/cm 2 , the thickness of the supported catalyst layer can be close to 10 ⁇ m.
  • the thickness of the supported catalyst layer can be, for example, about 0.1 to about 50 ⁇ m, more specifically on the order of about 20 to about 30 ⁇ m. Thicknesses above 50 ⁇ m appear to increase the mass transfer problems too much to be effective.
  • An appropriate thickness of supported catalyst can be determined by one of skill in the art.
  • the membrane of the MEA can be a dielectric, ionically-conductive material. It is desired that the membrane be sufficiently durable to withstand conditions within a fuel cell.
  • An appropriate membrane can be determined by one of skill in the art.
  • the membrane of the MEA can be an ionomer, specifically a perfluorosulfonate ionomer. More specifically, the membrane can be a poly(tetrafluoroethylene)-based cation exchange ionomer such as Nafion® (DuPont, Wilmington, DE; Fayetteville, NC). Nafion® is a perfluorinated polymer that contains small proportions of sulfonic or carboxylic ionic functional groups. Its general chemical structure can be seen below, where X is either a sulfonic or carboxylic functional group and M is either a metal cation in the neutralized form or an H + in the acid form.
  • the MEA comprises an anode, a cathode, and a membrane.
  • the anode can be an electrode of the present invention.
  • the electrode should be electrically conducting, porous enough to let reactants diffuse to the metal, and able to carry protons to the membrane.
  • the cathode can also be an electrode of the present invention.
  • FIG. 9 and 10 demonstrate the functionality of MEAs of the present invention.
  • FUEL CELL A fuel cell comprises an MEA, fuel feed, and oxidant feed.
  • a fuel cell typically comprises an MEA, backing layers, and flow fields/current collectors, fuel feed, and oxidant feed.
  • the hardware of the fuel cell can include backing layers.
  • the layers are generally one next to the anode and another next to the cathode and made of a porous carbon paper or carbon cloth. They layers are made of a material that can conduct the electrons exiting the anode and entering the cathode.
  • Backing layers are commercially available or can be prepared by one of skill in the art. Appropriate backing layers can be chosen by one of skill in the art.
  • the hardware of the fuel cell can include flow fields and current collectors. Pressed against the outer surface of each backing layer can be a piece of hardware, called a bipolar plate, which often serves the dual role of flow field and current collector.
  • the plates are generally made of a lightweight, strong, gas impermeable, electron-conducting material; graphite, metals, or composite plates are commonly used.
  • the bipolar plates can provide a gas flow field such as channels machined into the plate.
  • the channels carry the reactant gas from the point at which it enters the fuel cell to the point at which the gas exits.
  • the pattern, width, and depth have a large impact on the effectiveness of the distribution of the gases evenly across the active area of the membrane/electrode assembly.
  • the flow field also affects water supply to the membrane and water removal from the cathode.
  • the bipolar plates can also serve as current collectors. Electrons produced by the oxidation of hydrogen can be conducted through the anode, through the backing layer and through the plate before they can exit the cell, travel through an external circuit and re-enter the cell at the cathode plate.
  • Flow fields and current collectors are commercially available or can be prepared by one of skill in the art. Appropriate flow fields and current collectors can be chosen by one of skill in the art.
  • the devices and methods of the present invention are useful in preparing and using fuel cells.
  • Other applications can include electrodes and bipolar plates (or current collector plates) in energy conversion devices (such as fuel cells, batteries, or capacitors) when the current modified carbon products are used in combination with other materials.
  • energy conversion devices such as fuel cells, batteries, or capacitors
  • a method of the present invention comprises contacting a monomer of a conducting polymer containing hetero atoms and a particulate carbonaceous material in the presence of an oxidizing agent, thus effectively concurrently polymerizing the monomer and grafting the resultant polymer to the carbonaceous material.
  • the contacting can, but need not, take place in a liquid phase.
  • Any method which facilitates oxidative polymerization can be used.
  • One of skill in the art can determine a method to graft the conducting polymer (polymerize the monomer) to the carbonaceous material which maintains the purposes and characteristics of the invention.
  • the oxidizing agent can be added in stoichiometic amount/molar equivalent to the amount of monomer. For example, a 1 :1 mole ratio of monomer to oxidant was used for the Examples below.
  • the reaction can be carried out at room temperature and pressure. Specific examples of the reaction are given in the Examples below.
  • the reaction can be carried out, for example, at temperatures up to about 70°C.
  • An aqueous slurry of carbonaceous material can be used.
  • Slightly acidic conditions such as a pH of about 4 to about 5 can be used.
  • Reaction time of about 2 hours, for example, can be used.
  • the reaction can be carried out in the presence of an oxidizing agent.
  • An oxidizing agent is used to create sufficiently oxidizing conditions to facilitate polymerization of the monomer.
  • Various oxidizing agents are known in the art. These oxidizing agents are readily commercially available or readily synthesized by methods known to one of skill in the art.
  • oxidizing agents examples include ammomum persulfate, ferric chloride, hydrogen peroxide, potassium, permanganate, potassium chlorate, chloroplatinic acid, or a combination of oxidizing agents.
  • Some monomers require a stronger oxidizing agent than others.
  • the amount of oxidizing agent can be stoichiometric to the monomer, rather than being used in catalytic amounts.
  • One of skill in the art would be able to determine conditions, amount, and choice of oxidizing agent for a particular application.
  • Metal can be added to the polymer-grafted carbonaceous material subsequent to its preparation.
  • the metal can be added by metallizing. For example, if the metal is platinum, one method of platinization is described below.
  • a platinizing agent can be used to add platinum to the grafted carbonaceous material.
  • Various platinizing agents are known in the art. These platinizing agents are readily commercially available or readily synthesized by methods know to one of skill in the art. Choice of appropriate platinizing agent is readily determined by one of skill in the art for the desired application. Generally, anything containing the desired metal can be used, for example, any salt or organo-compound containing the metal.
  • platinizing agents examples include platinum salts: chloroplatinic acid, platinum nitrate, platinum halides, platinum cyanide, platinum sulf ⁇ de, organoplatinum salts, or a combination thereof.
  • the amount of platinizing agent is readily determined by one of skill in the art for a desired application.
  • the reaction can alternatively be carried out in the presence of a metal- containing oxidizing agent to essentially simultaneously form and graft the polymer and metallize the composition.
  • a metal-containing oxidizing agent is used to create sufficiently oxidizing conditions to facilitate polymerization of the monomer while including metal ions in the polymer.
  • metal-containing oxidizing agents are known in the art. These metal- containing oxidizing agents are readily commercially available or readily synthesized by methods known to one of skill in the art.
  • metal-containing oxidizing agents examples include chloroplatinic acid or a combination of metal-containing oxidizing agents.
  • Some monomers require a stronger metal-containing oxidizing agent than others.
  • the amount of metal-containing oxidizing agent can be stoichiometric to the monomer, rather than being used in catalytic amounts. However, the amount of metal- containing oxidizing agent and monomer can be selected based on the desired loading of metal in the final composition.
  • a reducing agent can be used to reduce the metal to metallic form.
  • Various reducing agents are known in the art. These reducing agents are readily commercially available or readily synthesized by methods known to one of skill in the art. The amount of reducing agent for the current method is always in excess of stoichiometric.
  • reducing agents examples include formaldehyde, formic acid, sodium borohydride, hydrogen, hydrazine, hydroxyl amine, or a combination of reducing agents.
  • Example 1 Preparation of polyaniline-grafted carbon black A slurry was made using 100 g CDX-975 carbon black (NSA surface area 240 m 2 /g and oil absorption of
  • a slurry was made using 100 g CDX-975 carbon black (NSA surface area 240 m 2 /g and oil absorption of
  • Example 4 Platinization of polyaniline-grafted carbon black 4 g of polyaniline-grafted carbon black (made in Example 1) was dispersed in 300 ml Dl water.
  • Example 5 Platinization of polyaniline-grafted carbon black 4 g of polyaniline grafted carbon black (made in Example 1) was dispersed in
  • Example 8 200 ml of 1% solution of chloroplatinic acid was added dropwise for a period of 1 hr. with continuous stirring. 200 ml of 3% solution of formaldehyde was added for a period of 1 hr., and the temperature was kept at 70°C for 1 hr. The slurry cooled to room temperature and was filtered by washing with Dl water. The carbon cake dried at 110°C for 4 hrs. and was pulverized. The resultant supported catalyst contained ⁇ 20% platinum with grafted polypyrrole on the carbon surface.
  • Example 8 200 ml of 1% solution of chloroplatinic acid was added dropwise for a period of 1 hr. with continuous stirring. 200 ml of 3% solution of formaldehyde was added for a period of 1 hr., and the temperature was kept at 70°C for 1 hr. The slurry cooled to room temperature and was filtered by washing with Dl water. The carbon cake dried at 110°C for 4 hrs. and
  • Simultaneous platinization and grafting of polypyrrole This method describes simultaneous platinization and grafting of polypyrrole to carbon black surface by using pyrrole, chloroplatinic acid, and sodium borohydride.
  • a slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of deionized water.
  • the slurry was heated to 70°C for 1 hr with continuous stirring. 0.75 g of sodium borohydride in 80 ml of deionized water was added to the above slurry at a rate of 2 ml/min and the reaction temperature was kept at 70°C for 1 hr.
  • the reduced carbon black slurry was cooled to room temperature, filtered, washed with deionized water, dried at 100°C for 4 hr, and pulverized.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polypyrrole-grafted carbon black as shown in Scheme HI.
  • Example 9 Simultaneous platinization and grafting of polyaniline This method describes simultaneous platinization and grafting of polyaniline to carbon black surface by using aniline, chloroplatinic acid, and sodium borohydride. A slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of deionized water.
  • aniline 6 g was added to 100 ml of deionized water, and the aniline solution added to the slurry with continuous stirring for 10 min. 15.5 ml of 10%> chloroplatinic acid was diluted with 80 ml of deionized water, and the chloroplatinic acid solution was added to the carbon black slurry at a rate of 2 ml/min.
  • the slurry was heated to 70°C for 1 hr with continuous stirring.
  • a solution containing 0.75 g of sodium borohydride in 80 ml of deionized water was added to the above slurry at a rate of 2 ml/min, and the reaction temperature was kept at 70°C for 1 hr.
  • the carbon black slurry was cooled to room temperature, filtered, washed with deionized water, dried at 100°C for 4 hr, and pulverized.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polyaniline-grafted carbon black as shown in Scheme HI.
  • Example 10 Simultaneous platinization and grafting of polypyrrole
  • This method describes simultaneous platinization and grafting of polypyrrole to carbon black surface by using pyrrole, chloroplatinic acid, and sodium borohydride. This method is similar to Example 8 except the reaction is carried out in ethanol.
  • a slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of reagent ethanol.
  • the slurry was heated to 70°C for 1 hr with continuous stirring. 0.75 g of sodium borohydride in 80 ml of reagent ethanol was added to the above slurry at a rate of 2 ml/min, and the reaction temperature was kept at 70°C for 1 hr.
  • the carbon black slurry was cooled to room temperature, filtered, washed with ethanol and deionized water, dried at 100°C for 4 hr, and pulverized.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polypyrrole-grafted carbon black as shown in Scheme m.
  • Example 11 Simultaneous platinization and grafting of polyaniline This method describes simultaneous platinization and grafting of polyaniline to carbon black surface by using aniline, chloroplatinic acid, and sodium borohydride. This method is similar to Example 9 except the reaction is carried out in ethanol.
  • a slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of reagent ethanol.
  • the carbon black slurry was cooled to room temperature, filtered, washed with ethanol and deionized water, dried at 100°C for 4 hr, and pulverized.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polyaniline-grafted carbon black as shown in Scheme HI.
  • Simultaneous platinization and grafting of polypyrrole This method describes simultaneous platinization and grafting of polypyrrole to carbon black surface by using pyrrole, chloroplatinic acid, and hydrogen.
  • a slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of deionized water.
  • the carbon black slurry was cooled to room temperature, filtered, washed with deionized water, dried at 100°C for 4 hr, and pulverized.
  • the carbon black powder was reduced using 10%o hydrogen/nitrogen mixture in a tubular furnace at 250°C for 2 hr.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polypyrrole-grafted carbon black as shown in Scheme HI.
  • Example 13 Simultaneous platinization and grafting of polyaniline This method describes simultaneous platinization and grafting of polyaniline to carbon black surface by using aniline, chloroplatinic acid, and hydrogen.
  • a slurry was made using 2 g of carbon black (CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g) in 400 ml of deionized water. , 6 g of aniline was added to 100 ml of deionized water, and the aniline solution was added to the slurry with continuous stirring for 10 min.
  • carbon black CDX-975, surface area of 240 m 2 /g and oil absorption of 170 ml/100 g
  • the carbon black slurry was cooled to room temperature, filtered, washed with deionized water, dried at 100°C for 4 hr, and pulverized.
  • the carbon black powder was reduced using 10%o hydrogen/nitrogen mixture in a tubular furnace at 250°C for 2 hr.
  • the resultant carbon black powder contains nano-crystalline platinum particles with polyaniline-grafted carbon black as shown in Scheme HI.
  • the pellets of carbon black material included conductive carbon black alone, grafted material from Example 1 and Example 3 above, and CDX-975 carbon black alone.
  • Table 1 demonstrates the increase in electronic conductivity of the catalyst supports of the present invention over carbon alone.
  • the pellets of carbon black material included conductive carbon black alone, simultaneously platinized grafted material from Example 8 above, and CDX-975 carbon black alone.
  • Table 2 demonstrates the increase in electronic conductivity of the catalyst supports of the present invention over carbon alone.
  • Table 3 compares the dispersion of Pt on carbon black (bulk, average value) in the supported catalysts of the present invention relative to a HiSPECTM supported catalyst. See also Figure 7.
  • Table 3 X-ray diffraction analysis of Pt dispersion in carbon black supported catalysts.
  • Table 4 compares the dispersion of Pt on carbon black (bulk, average value) in the supported catalysts of the present invention relative to a HiSPECTM supported catalyst. See also Figure 8. Table 4. X-ra diffraction analysis of Pt dis ersion in carbon black su orted catal sts.

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Abstract

L'invention concerne une composition comprenant un matériau carboné particulaire et un polymère conducteur contenant des hétéroatomes. Ladite composition peut également contenir un métal. Il est possible de construire des dispositifs contenant cette composition, tels que des électrocatalyseurs, des ensemble d'électrodes membranaires et des piles à combustible. L'invention concerne un procédé de préparation de la composition consistant à polymériser de manière oxydative un monomère de polymère conducteur contenant des hétéroatomes en présence d'un matériau carboné, la polymérisation oxydative s'effectuant en présence d'un agent d'oxydation contenant un métal. Ledit procédé permet de greffer le matériau carboné tout en métallisant simultanément la composition.
PCT/US2004/015567 2003-05-23 2004-05-18 Materiau carbone conducteur metallise a polymere greffe WO2004107359A1 (fr)

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US10/445,090 US7175930B2 (en) 2002-05-23 2003-05-23 Conducting polymer-grafted carbon material for fuel cell applications
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US7241334B2 (en) 2002-05-23 2007-07-10 Columbian Chemicals Company Sulfonated carbonaceous materials
US7708947B2 (en) 2005-11-01 2010-05-04 Therm-O-Disc, Incorporated Methods of minimizing temperature cross-sensitivity in vapor sensors and compositions therefor
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US8691390B2 (en) 2007-11-20 2014-04-08 Therm-O-Disc, Incorporated Single-use flammable vapor sensor films

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CN102895997A (zh) * 2012-10-25 2013-01-30 天津大学 直接甲醇燃料电池负载型Pt基阳极催化剂的制备方法

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