WO2003071621A2 - Electrocatalyseur de pile à combustible de pt-mo-ni/fe/sn/w - Google Patents

Electrocatalyseur de pile à combustible de pt-mo-ni/fe/sn/w Download PDF

Info

Publication number
WO2003071621A2
WO2003071621A2 PCT/US2003/005325 US0305325W WO03071621A2 WO 2003071621 A2 WO2003071621 A2 WO 2003071621A2 US 0305325 W US0305325 W US 0305325W WO 03071621 A2 WO03071621 A2 WO 03071621A2
Authority
WO
WIPO (PCT)
Prior art keywords
concentration
atomic percent
catalyst
platinum
molybdenum
Prior art date
Application number
PCT/US2003/005325
Other languages
English (en)
Other versions
WO2003071621A3 (fr
Inventor
Peter Strasser
Alexander Gorer
Martin Devenney
Qun Fan
Konstantinos Chondroudis
Daniel M. Gianquinta
Ting He
Hiroyuki Oyanagi
Kenta Urata
Kazuhiko Iwasaki
Hiroichi Fukuda
Original Assignee
Symyx Technologies, Inc.
Honda Giken Kogyo Kabushiki Kaisha
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 Symyx Technologies, Inc., Honda Giken Kogyo Kabushiki Kaisha filed Critical Symyx Technologies, Inc.
Priority to AU2003213202A priority Critical patent/AU2003213202A1/en
Publication of WO2003071621A2 publication Critical patent/WO2003071621A2/fr
Publication of WO2003071621A3 publication Critical patent/WO2003071621A3/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/04—Alloys based on a platinum group metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0238—Impregnation, coating or precipitation via the gaseous phase-sublimation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/344—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy
    • B01J37/346—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy of microwave energy
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C13/00—Alloys based on tin
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/04—Alloys based on tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • 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
    • H01M4/921—Alloys or mixtures with metallic elements
    • 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
    • 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
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • 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
    • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
    • 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 to metal alloys comprising platinum, molybdenum, and one or more metals selected from the group consisting of nickel, iron, tin, and tungsten or mixtures thereof.
  • the alloys are useful as catalysts, in general, and as electrocatalysts in fuel cell electrodes, in particular.
  • a fuel cell is an electrochemical device for directly converting the chemical energy generated from an oxidation-reduction reaction of a fuel such as hydrogen or hydrocarbon-based fuels and an oxidizer such as oxygen gas (in air) supplied thereto into a low-voltage direct current.
  • a fuel such as hydrogen or hydrocarbon-based fuels
  • an oxidizer such as oxygen gas (in air) supplied thereto into a low-voltage direct current.
  • a fuel cell is generally comprised of a fuel electrode (anode), an oxidizer electrode (cathode), an electrolyte interposed between the electrodes (alkaline or acidic), and means for separately supplying a stream of fuel and a stream of oxidizer to the anode and the cathode, respectively.
  • fuel supplied to the anode is oxidized, releasing electrons which are conducted via an external circuit to the cathode.
  • the supplied electrons are consumed when the oxidizer is reduced.
  • the current flowing through the external circuit can be made to do useful work.
  • a phosphoric acid fuel cell operates at about 160-220 °C, and preferably at about 190-200 °C. This type of fuel cell is currently being used for multi-megawatt utility power generation and for co-generation systems (i.e., combined heat and power generation) in the 50 to several hundred kilowatts range.
  • proton exchange membrane fuel cells use a solid proton- conducting polymer membrane as the electrolyte.
  • the polymer membrane is maintained in a hydrated form during operation in order to prevent loss of ionic conduction which limits the operation temperature typically to between about 70 and 5 about 120 °C depending on the operating pressure, and preferably below about 100 °C.
  • Proton exchange membrane fuel cells have a much higher power density than liquid electrolyte fuel cells (e.g., phosphoric acid), and can vary output quickly to meet shifts in power demand. Thus, they are suited for applications such as in automobiles and small scale residential power generation where quick startup is
  • pure hydrogen gas is the optimum fuel; however, in other applications where a lower operational cost is desirable a reformed hydrogen-containing gas is an appropriate fuel.
  • a reformed-hydrogen containing gas is produced, for example, by steam-reforming methanol and water at
  • the reformate gas consists of 75 vol% hydrogen and 25 vol% carbon dioxide. In practice, however, this gas also contains nitrogen, oxygen, and, depending on the degree of purity, varying amounts of carbon monoxide (up to 1 vol%).
  • this gas also contains nitrogen, oxygen, and, depending on the degree of purity, varying amounts of carbon monoxide (up to 1 vol%).
  • methanol is an especially desirable fuel because it has a high energy density, a low cost, and is produced from renewable resources.
  • electrocatalyst materials are typically provided at the electrodes.
  • fuel cells used electrocatalysts made of a single metal usually platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), silver (Ag) or gold (Au) because they are able to withstand the corrosive environment - platinum being the most efficient and 0 stable single-metal electrocatalyst for fuel cells operating below about 300 °C.
  • a factor contributing to this phenomenon include the fact that the desired reduction of oxygen to water is a four-electron transfer reaction and typically involves breaking a strong 0-0 bond early in the reaction.
  • the open circuit voltage is lowered from the thermodynamic potential for oxygen reduction due to the formation of peroxide and possible platinum oxides which inhibit the reaction.
  • a second challenge is the stability of the oxygen electrode (cathode) during long- term operation. Specifically, a fuel cell cathode operates in a regime in which even the most unreactive metals are not completely stable. Thus, alloy compositions which contain non-noble metal elements may have a rate of corrosion which would negatively impact the projected lifetime of a fuel cell. The corrosion may be more severe when the cell is operating near open circuit conditions (which is the most desirable potential for thermodynamic efficiency).
  • Electrocatalyst materials at the anode also face challenges during fuel cell operation. Specifically, as the concentration of carbon monoxide (CO) rises above about 10 ppm in the fuel the surface of the electrocatalyst can be rapidly poisoned. As a result, platinum (by itself) is a poor electrocatalyst if the fuel stream contains carbon monoxide (e.g., reformed-hydrogen gas typically exceeds 100 ppm). Liquid hydrocarbon-based fuels (e.g., methanol) present an even greater poisoning problem. Specifically, the surface of the platinum becomes blocked with the adsorbed intermediate, carbon monoxide (CO). It has been reported that H 2 O plays a key role in the removal of such poisoning species in accordance with the following reactions:
  • the methanol is adsorbed and partially oxidized by platinum on the surface of the electrode (1).
  • Adsorbed OH from the hydrolysis of water, reacts with the adsorbed CO to produce carbon dioxide and a proton (2,3).
  • platinum does not form OH species well at the potentials fuel cell electrodes operate (e.g., 200 mV-1.5 V).
  • step (3) is the slowest step in the sequence, limiting the rate of CO removal, thereby allowing poisoning of the electrocatalyst to occur. This applies in particular to a proton exchange membrane fuel cell which is especially sensitive to CO poisoning because of its low operating temperatures.
  • One technique for increasing electrocatalytic cathodic activity during the reduction of oxygen and electrocatalytic anodic activity during the oxidation of hydrogen is to employ an electrocatalyst which is more active, corrosion resistant, and/or more poison tolerant.
  • electrocatalyst which is more active, corrosion resistant, and/or more poison tolerant.
  • increased tolerance to CO has been reported by alloying platinum and ruthenium at a 50:50 atomic ratio (see, D. Chu and S. Gillman, J. Electrochem. Soc. 1996, 143, 1685).
  • the electrocatalysts proposed to date leave room for further improvement.
  • the present invention is directed to a catalyst for use in oxidation or reduction reactions, the catalyst composition comprising platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • the present invention is also directed to a supported electrocatalyst powder for use in electrochemical reactor devices, the supported electrocatalyst powder comprising a catalyst that comprises platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • the present invention is also directed to a fuel cell electrode, the fuel cell electrode comprising electrocatalyst particles and an electrode substrate upon which the electrocatalyst particles are deposited, the electrocatalyst particles comprising a catalyst that comprises platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • the present invention is also directed to a fuel cell comprising an anode, a cathode, a proton exchange membrane between the anode and the cathode, and a catalyst for the catalytic oxidation of a hydrogen-containing fuel or the catalytic reduction of oxygen, the catalyst comprising platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • the present invention is also directed to a method for the electrochemical conversion of a hydrogen-containing fuel and oxygen to reaction products and electricity in a fuel cell comprising an anode, a cathode, a proton exchange membrane therebetween, a catalyst, and an electrically conductive external circuit connecting the anode and cathode, the method comprising contacting the hydrogen-containing fuel or the oxygen and the catalyst to catalytically oxidize the hydrogen-containing fuel or catalytically reduce the oxygen, the catalyst comprising platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • FIG. 1 is a schematic structural view showing members of a fuel cell.
  • FIG. 2 is a cross-sectional side view of a fuel cell.
  • FIG. 3 is a photograph of an electrode array comprising thin-film alloy compositions deposited on individually addressable electrodes prepared as described in Example 1.
  • the present invention is directed to a multi-component metal-containing substance having electrocatalytic activity for use in fuel cells (e.g., an electrocatalyst).
  • the multi-component metal-containing substance is an alloy of the components.
  • the electrocatalyst may be a mixture of discrete amounts of the components (e.g., a mixture of metal powders or a mixture of deposits), wherein a discrete amount of the components may comprise a single component or a combination of components (e.g., an alloy).
  • the present invention is directed to a multi-component metal-containing substance (e.g., alloy or catalyst) that comprises platinum, molybdenum and a metal selected from the group consisting of nickel, iron, tin, and tungsten, provided (i) the concentration of each of nickel and iron is less than 70 atomic percent, and (ii) the concentration of nickel or iron is less than 20 atomic percent when the alloy contains both nickel and iron.
  • the catalyst composition of the present invention has an improved corrosion resistance and/or improved activity compared to platinum.
  • the catalyst consists essentially of platinum molybdenum and at least one of nickel, iron, tin, and tungsten.
  • a catalyst composition of the present invention comprises amounts of platinum, molybdenum and at least one of the metals selected from nickel, iron, tin, and tungsten such that the metals play a role in the catalytic activity and/or crystallographic structure of the alloy.
  • concentrations of platinum, molybdenum, and at least one of nickel, iron, tin, and tungsten are such that the presence of the metals would not be considered an impurity.
  • the concentrations of platinum, molybdenum, and the metal or metals selected from nickel, iron, tin, and tungsten are at least about 0.1 , 0.5, 1 , or even 5 atomic percent.
  • the concentration of platinum is generally less than about 70, 60, or 50 atomic percent of platinum. Also in one embodiment the concentration of molybdenum is less than about 60 atomic percent. In some embodiments of the present invention the concentration of platinum is between about 10 and about 50 atomic percent, and between about 20 and about 40 atomic percent. In some embodiments of the present invention the concentration of molybdenum is between about 5 and about 60 atomic percent, and between about 10 and about 50 atomic percent. In some embodiments of the present invention the sum of the concentrations of the metals selected from the group consisting of nickel, iron, tin, and tungsten is between about 5 and about 80 atomic percent, and between about 10 and about 70 atomic percent.
  • the alloys of the present invention are comprised entirely of the foregoing metals ⁇ i.e., they do not contain other constituents either metallic or non-metallic). However, it is possible that the alloys may comprise other constituents whether as intentional additions or as impurities. For example, many metal alloys may comprise oxygen and/or carbon either as an impurity or as a desired alloy constituent.
  • the alloys of the present invention while maintaining the same relative amounts of the constituents disclosed herein (i.e., platinum, molybdenum, nickel, iron, tin, and tungsten), may comprise less than 100 percent of the disclosed atoms. Thus, in several embodiments of the present invention the total concentration of the disclosed atoms is greater than about 70, 80, 90, 95, or 99 atomic percent of the electrocatalyst alloy.
  • the electrocatalyst is an alloy comprising platinum, molybdenum, and nickel.
  • the concentration of nickel is less than 70 atomic percent.
  • the electrocatalyst is an alloy that consists essentially of the platinum, molybdenum, and nickel.
  • the concentration of platinum is at a moderate amount and the molybdenum and nickel concentrations may vary throughout comparatively large ranges. For example, in one embodiment the concentration of platinum is between about 30 and about 55 atomic percent. In another embodiment the concentration of platinum is between about 35 and about 50 atomic percent.
  • the concentration of molybdenum in one embodiment is between about 1 and about 50 atomic percent. In another embodiment the concentration of molybdenum is between about 5 and about 35 atomic percent. In yet another embodiment the concentration of molybdenum is between about 10 and about 30 atomic percent. In one embodiment the concentration of nickel is typically between about 5 and about 55 atomic percent. In another embodiment the concentration of nickel is between about 25 and about 45 atomic percent.
  • the concentration of platinum is between about 30 and about 55 atomic percent
  • the concentration of molybdenum is between about 1 to about 50 atomic percent
  • the concentration of nickel is between about 5 and about 55 atomic percent.
  • the concentration of platinum is between about 35 and about 50 atomic percent
  • the concentration of molybdenum is between about 5 and about 35 atomic percent
  • the concentration of nickel is between about 25 and about 45 atomic percent.
  • the concentration of platinum is at least about 50 atomic percent.
  • the concentration of platinum is between about 50 and about 70 atomic percent
  • the concentration of molybdenum is between about 1 and about 10 atomic percent
  • the concentration of nickel is between about 20 and about 40 atomic percent.
  • the electrocatalyst is an alloy comprising platinum, molybdenum, and iron. In one embodiment the concentration of iron is less than 70 atomic percent. In another embodiment the electrocatalyst is an alloy that consists essentially of the platinum, molybdenum, and iron.
  • the concentration of each constituent metal may vary through a range.
  • the concentration of platinum is between about 15 and about 50 atomic percent. In another embodiment the concentration of platinum is between about 30 and about 40 atomic percent.
  • the concentration of molybdenum in one embodiment is between about 5 and about 55 atomic percent. In another embodiment the concentration of molybdenum is between about 8 and about 50 atomic percent.
  • the concentration of iron in one embodiment is between about 10 and about 60 atomic percent. In another embodiment the concentration of iron is between about 12 and about 56 atomic percent.
  • the concentration of platinum is between about 15 and about 50 atomic percent
  • the concentration of molybdenum is between about 5 and about 55 atomic percent
  • the concentration of iron is between about 10 and about 60 atomic percent.
  • the concentration of platinum is between about 30 and about 40 atomic percent
  • the concentration of molybdenum is between about 8 and about 50 atomic percent
  • the concentration of iron is between about 12 and about 56 atomic percent.
  • the electrocatalyst is an alloy comprising platinum, molybdenum, and tin, and the concentration of each constituent metal may vary through a range.
  • concentration of platinum is between about 1 and about 70 atomic percent.
  • concentration of platinum is between about 10 and about 50 atomic percent.
  • concentration of molybdenum in one embodiment is between about 1 and about 70 atomic percent.
  • concentration of molybdenum is between about 20 and about 70 atomic percent.
  • the concentration of tin is between about 1 and about 70 atomic percent.
  • the concentration of tin is between about 5 and about 55 atomic percent.
  • the concentration of platinum is between about 10 and about 50 atomic percent
  • the concentration of molybdenum is between about 20 and about 70 atomic percent
  • the concentration of tin is between about 5 and about 55 atomic percent.
  • the concentration of molybdenum is no more than about 10 atomic percent.
  • the concentration of platinum is between about 30 and about 50 atomic percent
  • the concentration of molybdenum is between about 1 and about 10 atomic percent
  • the concentration of tin is between about 40 and about 60 atomic percent.
  • the concentration of molybdenum is at least about 40 atomic percent.
  • the concentration of platinum is between about 10 and about 50 atomic percent
  • the concentration of molybdenum is between about 40 and about 70 atomic percent
  • the concentration of tin is between about 5 and about 35 atomic percent.
  • the electrocatalyst is an alloy comprising platinum, molybdenum, and tungsten, and the concentration of each constituent metal may vary through a range.
  • concentration of platinum in such alloys is between about 10 and about 60 atomic percent.
  • concentration of platinum is between about 20 and about 50 atomic percent.
  • concentration of platinum is between about 30 and about 40 atomic percent.
  • concentration of molybdenum in one embodiment is between about 10 and about 70 atomic percent.
  • the concentration of molybdenum is between about 10 and about 40 atomic percent.
  • the concentration of molybdenum is between about 10 and about 30 atomic percent. In one embodiment the concentration of tungsten is between about 10 and about 60 atomic percent. In another embodiment the concentration of tungsten is between about 10 and about 60 atomic percent. In yet another embodiment the concentration of tungsten is between about 30 and about 60 atomic percent.
  • the concentration of platinum is between about 10 and about 60 atomic percent
  • the concentration of molybdenum is between about 10 and about 70 atomic percent
  • the concentration of tungsten is between about 10 and about 60 atomic percent.
  • the concentration of platinum is between about 20 and about 50 atomic percent
  • the concentration of molybdenum is between about 10 and about 40 atomic percent
  • the concentration of tungsten is between about 10 and about 60 atomic percent.
  • the concentration of platinum is between about 30 and about 40 atomic percent
  • the concentration of molybdenum is between about 10 and about 30 atomic percent
  • the concentration of tungsten is between about 30 and about 60 atomic percent.
  • Pt-Mo-Sn/W alloy electrocatalyst compositions In accordance with one embodiment of the present invention, the electrocatalyst is an alloy comprising platinum, molybdenum, tin, and tungsten, and the concentration of each constituent metal may vary through a range. For example, in one embodiment the concentration of platinum is between about 10 and about 30 atomic percent. Similarly, the concentration of molybdenum is between about 10 and about 30 atomic percent.
  • the concentration of tin is between about 30 and about 50 atomic percent and the concentration of tungsten is between about 10 and about 30 atomic percent.
  • the stoichiometric alloy compositions of the present invention refer to overall stoichiometries, or bulk stoichiometries, of a prepared electrocatalysts prior to being subjected to an electrocatalytic reaction. That is, a reported alloy composition is an average stoichiometry over the entire volume of the prepared electrocatalyst composition, and therefore, localized stoichiometric variations may exist. For example, the volume of an electrocatalyst alloy particle comprising the surface and the first few atomic layers inward therefrom may differ from the bulk stoichiometry.
  • the surface stoichiometry corresponding to a particular bulk stoichiometry is highly dependant upon the method and conditions under which the electrocatalyst alloy is prepared and alloys having the same bulk stoichiometry may have significantly different surface stoichiometries. Without being bound to a particular theory, it is believed the differing surface stoichiometries is due at least in part to differences in the atomic arrangements, chemical phases and homogeneity of the electrocatalysts.
  • an electrocatalyst composition may change the composition by leaching one or more alloy constituents from the alloy (see, Catalysis for Low Temperature Fuel Cells Part 1 : The Cathode Challenges, T.R. Ralph and M.P. Hogarth, Platinum Metals Rev., 2002, 46, (1 ), p. 3-14).
  • This leaching effect may, in fact, increase the activity of the electrocatalyst by increasing the surface area and/or by changing the surface composition of the electrocatalyst.
  • the purposeful leaching of electrocatalyst compositions after synthesis to increase the surface area has been disclosed by Itoh et al.
  • alloy compositions of the present invention are intended to include starting bulk stoichiometries, any starting surface stoichiometries resulting therefrom, and modifications of the starting bulk and/or surface stoichiometries that are produced by subjecting the electrocatalyst to an electrocatalytic reaction.
  • the electrocatalyst alloys of the present invention may be formed by a variety of methods.
  • the appropriate amounts of the constituents may be mixed together and heated to a temperature above the respective melting points to form a molten solution of the metals which is cooled and allowed to solidify.
  • electrocatalysts are used in a powder form to increase the surface area which increases the number of reactive sites and leads to improved efficiency of the cell.
  • the formed metal alloy may be transformed into a powder after being solidified (e.g., by grinding) or during solidification (e.g., spraying molten alloy and allowing the droplets to solidify). It may, however, be advantageous to evaluate alloys for electrocatalytic activity in a non-powder form (see, Examples 1 and 2, infra).
  • an electrocatalyst alloy for use in a fuel cell may deposited over the surface of electrically conductive supports (e.g., carbon black).
  • One method for loading an electrocatalyst alloy onto supports typically comprises depositing metal precursor compounds onto the supports, and converting the precursor compounds to metallic form and alloying the metals using a heat-treatment in a reducing atmosphere (e.g., an atmosphere comprising an inert gas such as argon).
  • a reducing atmosphere e.g., an atmosphere comprising an inert gas such as argon.
  • One method for depositing the precursor compounds involves chemical precipitation of precursor compounds onto the supports.
  • the chemical precipitation method is typically accomplished by mixing supports and sources of the precursor compounds (e.g., an aqueous solution comprising one or more inorganic metallic salts) at a concentration sufficient to obtain the desired loading of the electrocatalyst on the supports and then precipitation of the precursor compounds is initiated (e.g., by adding an ammonium hydroxide solution).
  • the slurry is then typically filtered from the liquid under vacuum, washed with deionized water, and dried to yield a powder that comprises the precursor compounds on the supports.
  • Another method for depositing the precursor compounds comprises forming a suspension comprising a solution and supports suspended therein, wherein the solution comprises a solvent portion and a solute portion that comprises the constituents of the precursor compound(s) being deposited.
  • the suspension is frozen to deposit (e.g., precipitate) the precursor compound(s) on the particles.
  • the frozen suspension is freeze-dried to remove the solvent portion and leave a freeze-dried powder comprising the supports and the deposits of the precursor compound(s) on the supports.
  • the temperature reached during the thermal treatment is typically at least as high as the decomposition temperature(s) for the precursor compound(s) and not be so high as to result in degradation of the supports and agglomeration of the supports and/or the electrocatalyst deposits.
  • the temperature is between about 60 °C and about 1100 °C.
  • Inorganic metal-containing compounds typically decompose at temperatures between about 600 and about 1000 °C.
  • the duration of the heat treatment is typically at least sufficient to substantially convert the precursor compounds to the desired state. In general, the temperature and time are inversely related (i.e., conversion is accomplished in a shorter period of time at higher temperatures and vice versa). At the temperatures typical for converting the inorganic metal-containing compounds to a metal alloy set forth above, the duration of the heat treatment is typically at least about 30 minutes. In one embodiment, the duration is between about 2 and about 8 hours.
  • a fuel cell generally indicated 21 , comprises a fuel electrode, or anode, 2 and an air electrode, oxidizer electrode or cathode, 3.
  • a proton exchange membrane 1 serves as an electrolyte and it is usually a strongly acidic ion exchange membrane such as a perfluorosulphonic acid-based membrane.
  • the proton exchange membrane 1 , the anode 2, and the cathode 3 are integrated into one body to minimize contact resistance between the electrodes and the proton exchange membrane.
  • Current collectors 4 and 5 engage the anode and the cathode, respectively.
  • a fuel chamber 8 and an air chamber 9 contain the respective reactants and are sealed by sealants 6 and 7, respectively.
  • electricity is generated by hydrogen-containing fuel combustion
  • the hydrogen-containing fuel and oxygen react to form water, carbon dioxide and electricity.
  • This is accomplished in the above-described fuel cell by introducing the hydrogen-containing fuel F into the fuel chamber 8, while oxygen O (preferably air) is introduced into the air chamber 9, whereby an electric current can be immediately transferred between the current collectors 4 and 5 through an outer circuit (not shown).
  • oxygen O preferably air
  • the hydrogen-containing fuel is oxidized at the anode 2 to produce hydrogen ions, electrons, and possibly carbon dioxide gas.
  • the hydrogen ions migrate through the strongly acidic proton exchange membrane 1 and react with oxygen and electrons transferred through the outer circuit to the cathode 3 to form water.
  • the hydrogen-containing fuel F is methanol, it is preferably introduced as a dilute acidic solution to enhance the chemical reaction, thereby increasing power output (e.g., a 0.1 M methanol/0.5 M sulfuric acid solution).
  • the material of the proton exchange membrane is typically selected to be resistant to dehydration at temperatures up to between about 100 and about 120 °C.
  • Proton exchange membranes usually have reduction and oxidation stability, resistance to acid and hydrolysis, sufficiently low electrical resistivity (e.g., ⁇ 10 ⁇ » cm), and low hydrogen or oxygen permeation.
  • proton exchange membranes are usually hydrophilic. This ensures proton conduction (by reversed diffusion of water to the anode), and prevents the membrane from drying out thereby reducing the electrical conductivity.
  • the layer thickness of the membranes is typically between 50 and 200 ⁇ m.
  • Suitable proton-conducting membranes also include perfluorinated sulfonated polymers such as NAFION and its derivatives produced by E.I. du Pont de Nemours & Co., Wilmington, Delaware.
  • NAFION is based on a copolymer made from tetrafluoroethylene and perfluorovinylether, and is provided with sulfonic groups working as ion-exchanging groups.
  • the electrodes of the present invention comprise the electrocatalyst compositions of the present invention and an electrode substrate upon which the electrocatalyst is deposited.
  • the electrocatalyst alloy is directly deposited on the electrode substrate.
  • the electrocatalyst alloy is supported on electrically conductive supports and the supported electrocatalyst is deposited on the electrode substrate.
  • the electrode may also comprise a proton conductive material that is in contact with the electrocatalyst.
  • the proton conductive material may facilitate contact between the electrolyte and the electrocatalyst, and may thus enhance fuel cell performance.
  • the electrode is designed to increase cell efficiency by enhancing contact between the reactant (i.e., fuel or oxygen), the electrolyte and the electrocatalyst.
  • the reactant i.e., fuel or oxygen
  • porous or gas diffusion electrodes are typically used since they allow the fuel/oxidizer to enter the electrode from the face of the electrode exposed to the reactant gas stream (back face), and the electrolyte to penetrate through the face of the electrode exposed to the electrolyte (front face), and reaction products, particularly water, to diffuse out of the electrode.
  • the electrically conductive support particles typically comprise an inorganic material such as carbon.
  • the support particles may comprise an organic material such as an electrically conductive polymer (see, U.S. Pat. Appln. 2002/0132040 A1 ).
  • Carbon supports may be predominantly amorphous or graphitic and they may be prepared commercially, or specifically treated to increase their graphitic nature (e.g., heat treated at a high temperature in vacuum or in an inert gas atmosphere) thereby increasing corrosion resistance.
  • it may be oil furnace black, acetylene black, graphite paper, carbon fabric, or carbon aerogel.
  • a carbon aerogel preferably has an electrical conductivity of between 10 "2 and 10 3 ⁇ "1» cm “1 and a density of between 0.06 and 0.7 g/cm 3 ; the pore size is between 20 and 100 nm (porosity up to about 95%).
  • Carbon black support particles may have a Brunauer, Emmett and Teller (BET) surface area up to about 2000 m 2 /g. It has been reported that satisfactory results are achieved using carbon black support particles having a high mesoporous area, e.g., greater than about 75 m 2 /g (see, Catalysis for Low Temperature Fuel Cells Part 1 : The Cathode Challenges, T.R. Ralph and M.P. Hogarth, Platinum Metals Rev., 2002, 46, (1 ), p. 3-14). Experimental results to date indicate that a surface area of about 500 m 2 /g is preferred.
  • the proton exchange membrane, electrodes, and electrocatalyst materials are in contact with each other. This is typically accomplished by depositing the electrocatalyst either on the electrode, or on the proton exchange membrane, and then placing the electrode and membrane in contact.
  • the alloy electrocatalysts of this invention can be deposited on either the electrode or the membrane by a variety of methods, including plasma deposition, powder application (the powder may also be in the form of a slurry, a paste, or an ink), chemical plating, and sputtering.
  • Plasma deposition generally entails depositing a thin layer (e.g., between 3 and 50 ⁇ m, preferably between 5 and 20 ⁇ m) of an electrocatalyst composition on the membrane using low-pressure plasma.
  • a thin layer e.g., between 3 and 50 ⁇ m, preferably between 5 and 20 ⁇ m
  • an organic platinum compound such as trimethylcyclopentadienylplatinum is gaseous between 10 "4 and 10 mbar and can be excited using radio-frequency, microwaves, or an electron cyclotron resonance transmitter to deposit platinum on the membrane.
  • electrocatalyst powder is distributed onto the proton exchange membrane surface and integrated at an elevated temperature under pressure.
  • the electrocatalyst particles exceeds about 2 mg/cm 2 the inclusion of a binder such as polytetrafluoroethylene is common.
  • the electrocatalyst may be plated onto dispersed small support particles (e.g., the size is typically between 20 and 200 A, and more preferably between about 20 and 100 A). This increases the electrocatalyst surface area which in turn increases the number of reaction sites leading to improved cell efficiency.
  • a powdery carrier material such as conductive carbon black is contacted with an aqueous solution or aqueous suspension (slurry) of compounds of metallic components constituting the alloy to permit adsorption or impregnation of the metallic compounds or their ions on or in the carrier.
  • a dilute solution of suitable fixing agent such as ammonia, hydrazine, formic acid, or formalin is slowly added dropwise to disperse and deposit the metallic components on the carrier as insoluble compounds or partly reduced fine metal particles.
  • the loading, or surface concentration, of an electrocatalyst on the membrane or electrode is based in part on the desired power output and cost for a particular fuel cell.
  • power output increases with increasing concentration; however, there is a level beyond which performance is not improved.
  • cost of a fuel cell increases with increasing concentration.
  • the surface concentration of electrocatalyst is selected to meet the application requirements.
  • a fuel cell designed to meet the requirements of a demanding application such as an extraterrestrial vehicle will usually have a surface concentration of electrocatalyst sufficient to maximize the fuel cell power output.
  • economic considerations dictate that the desired power output be attained with as little electrocatalyst as possible.
  • the loading of electrocatalyst is between about 0.01 and about 6 mg/cm 2 .
  • Experimental results to date indicate that in some embodiments the electrocatalyst loading is preferably less than about 1 mg/cm 2 , and more preferably between about 0.1 and 1 mg/cm 2 .
  • the layers are usually compressed at high temperature.
  • the housings of the individual fuel cells are configured in such a way that a good gas supply is ensured, and at the same time the product water can be discharged properly.
  • several fuel cells are joined to form stacks, so that the total power output is increased to economically feasible levels.
  • the electrocatalyst compositions and fuel cell electrodes of the present invention may be used to electrocatalyze any fuel containing hydrogen (e.g., hydrogen and reformated-hydrogen fuels).
  • the improved electrocatalytic activity of the electrocatalyst compositions are particularly realized in the electrocatalysis of hydrocarbon-based fuels.
  • Applicable hydrocarbon-based fuels include saturated hydrocarbons such as methane (natural gas), ethane, propane and butane; garbage off-gas; oxygenated hydrocarbons such as methanol and ethanol; and fossil fuels such as gasoline and kerosene; and mixtures thereof.
  • the most preferred fuel is methanol.
  • suitable acids gases or liquids
  • SO 2 , SO 3 sulfuric acid, trifluoromethanesulfonic acid or the fluoride thereof, also strongly acidic carboxylic acids such as trifluoroacetic acid, and volatile phosphoric acid compounds may be used ("Ber. Bunsenges. Phys. Chem.”, Volume 98 (1994), pages 631 to 635).
  • the alloy compositions of the present invention are useful as electrocatalysts in fuel cells which generate electrical energy to perform useful work.
  • the alloy compositions may be used in fuel cells which are in electrical utility power generation facilities; uninterrupted power supply devices; extraterrestrial vehicles; transportation equipment such as heavy trucks, automobiles, and motorcycles (see, Fuji et al., U.S. Pat. No. 6,048,633; Shinkai et al., U.S. Pat. No. 6,187,468; Fuji et al., U.S. Pat. No. 6,225,011 ; and Tanaka et al., U.S. Pat. No.
  • Example 1 Forming Electrocatalytic Alloys on Individually Addressable Electrodes
  • an array of independent electrodes may be fabricated on inert substrates (e.g., glass, quartz, sapphire alumina, plastics, and thermally treated silicon).
  • the individual electrodes were located substantially in the center of the substrate, and were connected to contact pads around the periphery of the substrate with wires.
  • the electrodes, associated wires, and contact pads were fabricated from a conducting material (e.g., titanium, gold, silver, platinum, copper or other commonly used electrode materials).
  • a conducting material e.g., titanium, gold, silver, platinum, copper or other commonly used electrode materials.
  • the alloy compositions set forth in Tables A-E were prepared using a photolithography/RF magnetron sputtering technique (GHz range) to deposit thin-film alloys on arrays of 64 individually addressable electrodes.
  • a quartz insulating substrate was provided and photolithographic techniques were used to design and fabricate the electrode patterns on it.
  • photoresist By applying a predetermined amount of photoresist to the substrate, photolyzing preselected regions of the photoresist, removing those regions that have been photolyzed (e.g., by using an appropriate developer), depositing a layer of titanium about 500 nm thick using RF magnetron sputtering over the entire surface and removing predetermined regions of the deposited titanium (e.g. by dissolving the underlying photoresist), intricate patterns of individually addressable electrodes were fabricated on the substrate. Referring to FIG.
  • the fabricated array 20 consisted of 64 individually addressable electrodes 21 (about 1.7 mm in diameter) arranged in an 8 x 8 square that were insulated from each other (by adequate spacing) and from the substrate 24 (fabricated on an insulating substrate), and whose interconnects 22 and contact pads 23 were insulated from the electrochemical testing solution (by the hardened photoresist or other suitable insulating material).
  • a patterned insulating layer covering the wires and an inner portion of the peripheral contact pads, but leaving the electrodes and the outer portion of the peripheral contact pads exposed (preferably approximately half of the contact pad is covered with this insulating layer) was deposited.
  • the insulating layer Because of the insulating layer, it is possible to connect a lead (e.g., a pogo pin or an alligator clip) to the outer portion of a given contact pad and address its associated electrode while the array is immersed in solution, without having to worry about reactions that can occur on the wires or peripheral contact pads.
  • a lead e.g., a pogo pin or an alligator clip
  • the insulating layer was a hardened photoresist, but any other suitable material known to be insulating in nature could have been used (e.g., glass silica, alumina, magnesium oxide, silicon nitride, boron nitride, yttrium oxide, or titanium dioxide).
  • a steel mask having 64 holes (1.7 mm in diameter) was pressed onto the substrate to prevent deposition of sputtered material onto the insulating resist layer.
  • the deposition of the electrocatalyst alloys was also accomplished using RF magnetron sputtering and a two shutter masking system as described by Wu et al. which enable the deposition of material onto 1 or more electrodes at a time.
  • Each individual thin-film electrocatalyst alloy is created by a super lattice deposition method. For example, when preparing a ternary alloy electrocatalyst composition, metals M1 , M2 and M3 are to be deposited and alloyed onto one electrode.
  • a metal M1 sputter target is selected and a thin film of M1 having a defined thickness is deposited on the electrode.
  • This initial thickness is typically from about 3 to about 12 A.
  • metal M2 is selected as the sputter target and a layer of M2 is deposited onto the layer of M1.
  • the thickness of M2 layer is also from about 3 to about 12 A.
  • the thicknesses of the deposited layers are in the range of the diffusion length of the metal atoms (e.g., about 10 to about 30 A) which allows in-situ alloying of the metals.
  • a layer of M3 is deposited onto the M1-M2 alloy forming a M1-M2-M3 alloy film.
  • an alloy thin-film (9 - 25 A thickness) of the desired stoichiometry is created. This concludes one deposition cycle.
  • deposition cycles are repeated as necessary which results in the creation of a super lattice structure of a defined total thickness (typically about 700 A).
  • a computer program to design an output file which contains the information necessary to control the operation of the sputtering device during the preparation of a particular library wafer (i.e., array).
  • compositions of several as sputtered alloy compositions were analyzed using x-ray fluorescence (XRF) to confirm that they were consistent with desired compositions (chemical compositions determined using x-ray fluorescence are within about 5% of the actual composition).
  • Arrays were prepared to evaluate the specific alloy compositions set forth in Tables A-E. On each array one electrode consisted essentially of platinum and it served as an internal standard for the screening operation.
  • the results for the alloys may be evaluated against an external platinum standard comprising an array of 64 platinum electrodes in which the oxygen reduction activity of the 64 platinum electrodes averaged -0.35 mA/cm 2 at +0.1 V vs. a mercury/mercury sulfate electrode to determine the experimental error of the oxygen reduction test.
  • Example 2 Screening Alloys for Electrocatalytic Activity
  • the alloy compositions set forth in Tables A-E that were synthesized on arrays according the method set forth in Example 1 were screened in 1 M HCIO 4 5 electrolyte for electrochemical reduction of molecular oxygen to water to determine relative electrocatalytic activity against the internal and/or external platinum standard.
  • the array wafers were assembled into an electrochemical screening cell and a screening device established an electrical contact between the
  • each wafer array was placed into a screening device such that all 64 spots are facing upward and a tube cell body that was generally annular and having an inner diameter of about 2 inches (5 cm) was pressed onto the upward facing wafer surface. The diameter of this tubular cell was
  • a rotator shaft with blades was also placed into the electrolyte to provide forced convection-diffusion conditions during the screening.
  • the rotation rate was typically between about 300 to about 400 rpm.
  • either argon or pure oxygen was bubbled through the electrolyte during 5 the measurements.
  • Argon served to remove 0 2 gas in the electrolyte to simulate O 2 - free conditions used for the initial conditioning of the electrocatalysts.
  • the introduction of pure oxygen served to saturate the electrolyte with oxygen for the oxygen reduction reaction.
  • the electrolyte was maintained at 60 °C and the rotation rate was constant. Three groups of tests were performed to 0 screen the activity of the electrocatalysts.
  • the electrolyte (1 M HCIO was purged with argon for about 20 minutes prior to the electrochemical measurements.
  • the first group of tests comprised cyclic voltammetric measurements while purging the electrolyte with argon. Specifically, the first group of tests comprised: a. a potential sweep from about OCP to about +0.3 V to about -0.63 V and back to about +0.3 V at a rate of about 20 mV/s; b. twelve consecutive potential sweeps from OCP to about +0.3 V to about -0.7 V and back to about +0.3 V at a rate of about 200 mV/s; and c. a potential sweep from about OCP to about +0.3 V to about -0.63 V and back to about +0.3 V at a rate of about 20 mV/s.
  • the electrolyte was then purged with oxygen for approximately 30 minutes.
  • the following second group of tests were performed while continuing to purge with oxygen: a. measuring the open circuit potential (OCP) for a minute; then, starting at OCP the voltage was swept down to about -0.4 V at a rate of about 10 mV/s; b. measuring the OCP for a minute; then applying a potential step from OCP.
  • OCP open circuit potential
  • the third group of tests comprised a repeat of the second group of tests after about one hour from completion of the second group of tests.
  • the electrolyte was continually stirred and purged with oxygen during the waiting period. All the foregoing test voltages are with reference to a mercury/mercury sulfate (MMS) electrode.
  • MMS mercury/mercury sulfate
  • the screening results in Tables A-E are for the third test group steady state currents at +0.1 V MMS.
  • the current value reported (End Current Density) is the result of averaging the last three current values of the chronoamperometric test normalized for geometric surface area.
  • the Pt-Mo-Ni alloy compositions corresponding to Electrode Numbers 61 , 60, 62, 59, 63 and 58 exhibited an oxygen reduction activity greater than a platinum standard.
  • the Pt-Mo-Fe alloy compositions corresponding to Electrode Numbers 23, 51 , 44, 37, 17, 18, 52, 25, 30, 11 and 10 exhibited an oxygen reduction activity greater than a platinum standard.
  • the Pt-Mo-Sn-W alloy composition corresponding to Electrode Number 29 of Table B exhibited an oxygen reduction activity greater than a platinum standard.
  • the Pt-Mo-Sn alloy compositions corresponding to Electrode Numbers 25, 62, 57, and 14 of Table C and Electrode Numbers 1 , 52, 27, 33, 38, 28, 14, 43, and 45 of Table E exhibited an oxygen reduction activity greater than a platinum standard.
  • the Pt-Mo-W alloy compositions corresponding to Electrode Numbers 61 , 64, and 5 of Table C and to the Electrode Numbers Electrode Numbers 44, 51 , 37, 31 , 38, 45, 52, 25, 46, and 6 of Table D exhibited an oxygen reduction activity greater than a platinum standard.
  • Example 3 Synthesis of Supported Electrocatalyst Alloys
  • the synthesis of Pt 45 Mo 19 Ni 36 , Pt 36 Mo 21 W 42 , and Pt 36 Mo 19 Fe 45 alloys (see, Table F, Target Catalyst Comp.) on carbon support particles was attempted according to different process conditions in order to evaluate the performance of the alloys while in a state that is typically used in fuel cell. To do so, the alloy component precursors were deposited or precipitated on supported platinum powder (i.e., platinum nanoparticles supported on carbon black particles). Platinum supported on carbon black is commercially available from companies such as Johnson Matthey, Inc., of New Jersey and E-Tek Div. of De-Nora, N.A., Inc., of Sommerset, New Jersey.
  • Such supported platinum powder is available with a wide range of platinum loading.
  • the supported platinum powder used in this example had a nominal platinum loading of about 40 percent by weight, a platinum surface area of between about 150 and about 170 m 2 /g (determined by CO adsorption), a combined carbon and platinum surface area between about 350 and about 400 m 2 /g (determined by N 2 adsorption), and an average particle size of less than about 0.5 mm (determined by sizing screen).
  • the supported electrocatalyst alloys corresponding to HG-3-700, HG-3-900, HFC 42, 43, 36, 37, 22, and 23 were synthesized on carbon support particles using a chemical precipitation method according to the following steps.
  • a chemical precipitation method according to the following steps.
  • about 0.5 g of carbon supported platinum powder (37.9 wt% Pt) was dispersed in about 200 mL of room temperature 18 M ⁇ deionized water using an ultrasonic blending device (e.g., an AQUASONIC 50 D set at power level 9) for about 2 hours to form a slurry.
  • an ultrasonic blending device e.g., an AQUASONIC 50 D set at power level 9
  • the slurry was stirred using a magnetic stirring 5 device, and while being stirred, appropriate volumes based on the targeted electrocatalyst composition of one or more appropriate solutions comprising the metals to be alloyed with the platinum nanoparticles were added drop-wise to the slurry (e.g., a 1 M ammonium molybdate aqueous solution, a 1 M nickel nitrate aqueous solution, a 1 M iron (III) nitrate nonahydrate aqueous solution, a 1 M tin (IV)
  • MS, 152, 153, 156, and 157 were formed on carbon support particles using a freeze-drying precipitation method.
  • the freeze-drying method comprised forming a precursor solution comprising the desired metal atoms in the desired concentrations.
  • a precursor solution comprising the desired metal atoms in the desired concentrations.
  • the first source solution (the molybdenum-containing solution) was introduced into the HDPE vial containing the 0.200g of supported platinum powder with the same platinum loading, resulting in a black suspension.
  • the suspension was homogenized by immersing a probe of a BRANSON SONIFIER 150 into the vial and sonicating the mixture for about 30 seconds at a power level of 3. Subsequently, the
  • the tin-containing solution 20 second source solution (the tin-containing solution) was introduced into the vials, which contained the suspensions of the carbon supported platinum and molybdenum-containing solution.
  • the suspension was further homogenized by sonicating the mixture for an additional 1 minute at a power level of 3.
  • each vial contained a powder comprising the supported platinum powder, and molybdenum, nickel, tungsten, tin, and/or iron precursors deposited thereon.
  • the recovered precursor powders (both precipitated and freeze-dried) were then subjected to a heat treatment to reduce the precursors to their metallic state, and to alloy the metals with each other and the platinum on the carbon black particles.
  • One particular heat treatment comprised heating the powder in a quartz flow furnace with an atmosphere comprising about 6% H 2 and 94% Ar using a temperature profile of room temperature to about 40 °C at a rate of about 5 °C/min; holding at about 40 °C for 2 hours; increasing the temperature to about 200 °C at a rate of 5 °C/min; holding at about 200 °C for two hours; increasing the temperature at a rate of about 5 °C/min to about 700 or 900 °C; holding at a max temperature of about 700 or 900 °C for a duration of about two, three, six, or eight hours (indicated in Table F); and cooling down to room temperature.
  • the differently prepared alloys e.g., by composition variation or by heat treatment variation
  • ICP elemental analysis or subjected to EDS (Electron Dispersive Spectroscopy) elemental analysis.
  • EDS Electro Dispersive Spectroscopy
  • Example 4 Evaluating the Electrocatalytic Activity of Supported Electrocatalysts
  • the supported alloy electrocatalysts set forth in Table F and formed according to Example 3 were subjected to electrochemical measurements to evaluate their activities.
  • the supported alloy electrocatalysts were applied to a rotating disk electrode (RDE) as is commonly used in the art (see, Rotating disk electrode measurements on the CO tolerance of a high-surface area Pt/Vulcan carbon fuel cell electrocatalyst, Schmidt et al., Journal of the Electrochemical Society (1999), 146(4), 1296-1304; and Characterization of high- surface-area electrocatalysts using a rotating disk electrode configuration, Schmidt et al., Journal of the Electrochemical Society (1998), 145(7), 2354-2358).
  • RDE rotating disk electrode
  • Rotating disk electrodes are a relatively fast and simple screening tool for evaluating supported electrocatalysts with respect to their intrinsic electrolytic activity for oxygen reduction (e.g., the cathodic reaction of a fuel cell).
  • the rotating disk electrode was prepared by depositing an aqueous-based ink that comprises the support electrocatalyst and a NAFION solution on a glassy carbon disk.
  • the concentration of electrocatalyst powder in the NAFION solution was about 1 mg/mL.
  • the NAFION solution comprised the perfluorinated ion- exchange resin, lower aliphatic alcohols and water, wherein the concentration of resin is about 5 percent by weight.
  • the NAFION solution is commercially available from the ALDRICH catalog as product number 27,470-4.
  • the glassy carbon electrodes were 5 mm in diameter and were polished to a mirror finish. Glassy carbon electrodes are commercially available, for example, from Pine Instrument Company of Grove City, Pennsylvania. An aliquot of 10 ⁇ L electrocatalyst suspension was added to the carbon substrate and allowed to dry at a temperature between about 60 and 70 °C. The resulting layer of NAFION and electrocatalyst was less than about 0.2 ⁇ m thick. This method produced slightly different platinum loadings for each electrode made with a particular suspension, but the variation was determined to be less than about 10 percent by weight. After being dried, the rotating disk electrode was immersed into an electrochemical cell comprising an aqueous 0.5 M H 2 S0 4 electrolyte solution maintained at room temperature.
  • the electrochemical cell was purged of oxygen by bubbling argon through the electrolyte for about 20 minutes. All measurements were taken while rotating the electrode at about 2000 rpm, and the measured current densities were normalized either to the glassy carbon substrate area or to the platinum loading on the electrode.
  • Two groups of tests were performed to screen the activity of the supported electrocatalysts.
  • the first group of tests comprised cyclic voltammetric measurements while purging the electrolyte with argon. Specifically, the first group comprised: a. two consecutive potential sweeps starting from OCP to about +0.35V then to about -0.65V and back to OCP at a rate of about 50 mV/s; b.
  • the second test comprised purging with oxygen for about 15 minutes followed by a potential sweep test for oxygen reduction while continuing to purge the electrolyte with oxygen.
  • potential sweeps from about -0.45 V to +0.35 V were performed at a rate of about 5 mV/s to evaluate the initial activity of the electrocatalyst as a function of potential and to create a geometric current density plot.
  • the electrocatalysts were evaluated by comparing the diffusion corrected activity at 0.15 V. All the foregoing test voltages are with reference to a mercury/mercury sulfate electrode. Also, it is to be noted that the oxygen reduction measurements for a glassy carbon RDE without an electrocatalyst did not show any appreciable activity within the potential window.
  • the above-described supported electrocatalyst alloy compositions were evaluated in accordance with the above-described method and the results are set forth in Table F.
  • the alloy compositions Pt 39 Mo 29 Ni 32 , Pt 68 Mo 4 Ni 28 Pt ⁇ Mo g Sn ⁇ , and Pt 40 Mo 25 W 35 exhibited oxygen reduction activities similar to that of carbon supported platinum.
  • the alloy composition of Pt 48 Mo 11 Fe 41 exhibited a marked increase in oxygen reduction activity over the carbon supported platinum powder.
  • the alloy compositions Pt 29 Mo 38 Sn 33 and Pt 24 Mo 48 Sn 28 exhibited oxygen reduction activities that were about half that of the carbon supported platinum; the Pt mass activity (i.e., activity per mass of platinum), however, is significantly greater than the carbon supported platinum.
  • the results of the evaluation also indicate, among other things, that it may take numerous iterations to develop a set of parameters for producing the target alloy composition. Also evidenced by the data, is that activity can be adjusted by changes in the processing conditions. For example, despite depositing the same amounts of metallic precursors, the HFC 142 electrocatalyst had a higher activity than the HFC 143 electrocatalyst.
  • This difference in activity may be due to several factors such as alloy homogeneity (e.g., an alloy, as defined above, may have regions in which the constituent atoms show a presence or lack of order, i.e., regions of solid solution within an ordered lattice, or some such superstructure), changes in the lattice parameter due to changes in the average size of component atoms, changes in particle size, and changes in crystallographic structure/symmetry.
  • alloy homogeneity e.g., an alloy, as defined above, may have regions in which the constituent atoms show a presence or lack of order, i.e., regions of solid solution within an ordered lattice, or some such superstructure
  • changes in the lattice parameter due to changes in the average size of component atoms
  • changes in particle size changes in crystallographic structure/symmetry.
  • Pt and Ni have a face-centered cubic (fee) structure whereas Mo and Fe often crystallize in a body-centered cubic (bec) structure.
  • symmetry variations are to be expected across a multi-component compositional range.
  • the lattice of the resulting alloy may be expected to change from an fee lattice to a tetragonal primitive lattice.
  • extended and/or complete solid solutions may exist between metals that are similar in size and/or electronic characteristics.
  • the 12-coordinate metallic radii of platinum, molybdenum, nickel and iron are 1.40 A, 1.40 A, 1.25 A, and 1.26 A, respectively, and as metals are substituted for platinum, the average metal radius, and consequently the observed lattice parameter of a disordered alloy may be expected to contract or expand accordingly.
  • the average radius may be used as an indicator of lattice changes as a function of stoichiometry, or alternatively, as an indicator of stoichiometry based on observed diffraction patterns.
  • the XRD determined contraction observed for HFC 23 was approximately 3.5% versus platinum, however, the XRD data showed both an ordered alloy structure with lattice parameters similar to PtFe and evidence of a disordered alloy with a lattice parameter similar to platinum metal. As the radius of molybdenum is similar to that of platinum, the substitution of molybdenum for platinum would not be expected to change the measured lattice parameters in a significant fashion in either the disordered or ordered alloy.
  • the predicted change in the average radius for the Pt 41 Mo 5 Sn 54 alloys was an increase of 7.7% versus platinum.
  • the XRD data showed HFC 36 and 37 to be mixed phase material containing both a disordered alloy with a lattice expansion of 1.1 % versus platinum as well as the PtSn phase. It cannot be determined, based on the similar sizes of Pt and Mo, that the observed PtSn phase did or did not contain Mo.
  • the predicted change in the average radius for the Pt 29 Mo 38 Sn 33 alloys was an expansion of about 5.0%. However, an expansion was not observed due to the presence of multiple phases. HFC 152 appeared to comprise Mo and PtSn phases.
  • HFC 153 appeared to comprise Mo 2 C and PtSn phases.
  • the predicted change in the average radius for the Pt 24 Mo 48 Sn 28 alloys (HFC 156 and 157) was an expansion of 4.4%. However, an expansion was not observed due to the presence of multiple phases that may include PtSn and Pt.
  • the synthetic complexity of this system is seen in that single phase materials are difficult to prepare, however in all cases the mixed phase materials display relative performances that exceed that of platinum.
  • the predicted change in the average radius for the Ptg 8 Mo 4 Ni 28 alloys HG-3-
  • HFC 140 and 141 were a contraction of 3.3% versus platinum.
  • the XRD determined contraction was about 1.8% for HG-3-700 and 3.7% for (HG-3-900). Both HG-3-700 and 900 appeared to be disordered.
  • the predicted change in the average radius for the Pt 39 Mo 29 Ni 32 alloys was a contraction of 2.8% versus platinum.
  • the XRD determined contraction was about 3.0%.
  • HFC 140 and 141 appeared to be disordered, however, HFC 141 appeared to be slightly more crystalline than HFC 140.
  • HFC 140 and 141 display significantly smaller particles than those seen for HG-3-700 and -900.
  • HFC 142 and 143 appeared to be disordered alloys.
  • the starting materials used to synthesize the alloy may play a role in the activity of the synthesized alloy.
  • using something other than a metal nitrate salt solution to supply the metal atoms may result in different activities.
  • Different methods of synthesis e.g., chemical precipitation and freeze-drying impregnation
  • Heat treatment parameters such as atmosphere, time, temperature, etc.
  • This optimization may involve balancing competing phenomena. For example, increasing the heat treatment temperature is generally known to improve the reduction of a metal salt to a metal which typically increases activity; however, it also tends to increase the size of the electrocatalyst alloy particle and decrease surface area, which decreases electrocatalytic activity.
  • Activity is defined as the maximum sustainable, or steady state, current (Amps) obtained from the electrocatalyst, when fabricated into an electrode, at a given electric potential (Volts). Additionally, because of differences in the geometric area of electrodes, when comparing different electrocatalysts, activity is often expressed in terms of current density (A/cm 2 ).
  • An alloy is a mixture comprising two or more metals.
  • An alloy may be described as a solid solution in which the solute and solvent atoms (the term solvent is applied to the metal that is in excess) are arranged at random, much in the same way as a liquid solution may be described. If some solute atoms replace some of those of the solvent in the structure of the latter, the solid solution may be defined as a substitutional solid solution. Alternatively, an interstitial solid solution is formed if a smaller atom occupies the interstices between the larger atoms. Combinations of the two types are also possible. Furthermore, in certain solid solutions, some level of regular arrangement may occur under the appropriate conditions resulting in a partial ordering that may be described as a superstructure.
  • An alloy as defined herein, is also meant to include materials which may comprise elements which are generally considered to be non-metallic.
  • some alloys of the present invention may comprise oxygen in atomic, molecular, and/or metallic oxide form.
  • some alloys of the present invention may comprise carbon in atomic, molecular, and/or metal carbide form. If present, the amount of oxygen and/or carbon in the alloy is typically at what is generally considered to be a low level (e.g., less than about 5 weight percent), however higher concentrations are also possible (e.g., up to about 10 weight percent).
  • a low level e.g., less than about 5 weight percent
  • concentrations e.g., up to about 10 weight percent.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Plasma & Fusion (AREA)
  • Toxicology (AREA)
  • Electromagnetism (AREA)
  • Catalysts (AREA)
  • Inert Electrodes (AREA)

Abstract

L'invention concerne une composition électrocatalytique améliorée de piles à combustibles en alliage métallique contenant du platine, du molybdène, et un métal sélectionné dans le groupe constitué de nickel, de fer, d'étain et de tungstène, (i) la concentration du nickel et du fer étant inférieure à 70 en pourcentage atomique, et (ii) la concentration du nickel ou du fer étant inférieure à 20 en pourcentage atomique, lorsque l'alliage contient à la fois du nickel et du fer.
PCT/US2003/005325 2002-02-20 2003-02-20 Electrocatalyseur de pile à combustible de pt-mo-ni/fe/sn/w WO2003071621A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003213202A AU2003213202A1 (en) 2002-02-20 2003-02-20 Fuel cell electrocatalyst of pt-mo-ni/fe/sn/w

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US35819202P 2002-02-20 2002-02-20
US60/358,192 2002-02-20

Publications (2)

Publication Number Publication Date
WO2003071621A2 true WO2003071621A2 (fr) 2003-08-28
WO2003071621A3 WO2003071621A3 (fr) 2004-12-02

Family

ID=27757717

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2003/005325 WO2003071621A2 (fr) 2002-02-20 2003-02-20 Electrocatalyseur de pile à combustible de pt-mo-ni/fe/sn/w

Country Status (2)

Country Link
AU (1) AU2003213202A1 (fr)
WO (1) WO2003071621A2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1526592A1 (fr) * 2003-10-23 2005-04-27 Cataler Corporation Catalyseur catodique pour pile à combustble
WO2007024489A2 (fr) * 2005-08-25 2007-03-01 Honda Motor Co., Ltd. Electrocatalyseurs contenant du platine, du tungstene, et du nickel ou du zirconium
WO2007067546A2 (fr) * 2005-12-06 2007-06-14 Honda Motor Co., Ltd. Électrocatalyseurs contenant du platine et du tungstène
WO2020061468A1 (fr) 2018-09-21 2020-03-26 Deringer-Ney, Inc. Alliages à base de platine-nickel, produits, et procédés de fabrication et d'utilisation correspondants

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113839053B (zh) * 2021-08-28 2024-04-09 西安交通大学 用于碱性直接甲醇燃料电池的非贵金属碳载镍锡氮化钽纳米电催化剂及其制备方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05217586A (ja) * 1992-02-07 1993-08-27 Fuji Electric Co Ltd 燃料電池およびその製造方法
JPH06379A (ja) * 1992-06-22 1994-01-11 Tanaka Kikinzoku Kogyo Kk 酸化触媒とその製造方法
EP0653242A1 (fr) * 1993-11-04 1995-05-17 Shell Internationale Researchmaatschappij B.V. Catalyseurs, procédés les utilisant et procédés pour les préparer
EP0838872A2 (fr) * 1996-10-25 1998-04-29 Johnson Matthey Public Limited Company Catalyseur amélioré
JPH10212592A (ja) * 1997-01-28 1998-08-11 Tanaka Kikinzoku Kogyo Kk 白金合金メッキ浴
US5922487A (en) * 1995-01-24 1999-07-13 Tanaka Kikinzoku Kogyo K.K. Anode electrocatalyst for fuel cell and process of preparing same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05217586A (ja) * 1992-02-07 1993-08-27 Fuji Electric Co Ltd 燃料電池およびその製造方法
JPH06379A (ja) * 1992-06-22 1994-01-11 Tanaka Kikinzoku Kogyo Kk 酸化触媒とその製造方法
EP0653242A1 (fr) * 1993-11-04 1995-05-17 Shell Internationale Researchmaatschappij B.V. Catalyseurs, procédés les utilisant et procédés pour les préparer
US5922487A (en) * 1995-01-24 1999-07-13 Tanaka Kikinzoku Kogyo K.K. Anode electrocatalyst for fuel cell and process of preparing same
EP0838872A2 (fr) * 1996-10-25 1998-04-29 Johnson Matthey Public Limited Company Catalyseur amélioré
JPH10212592A (ja) * 1997-01-28 1998-08-11 Tanaka Kikinzoku Kogyo Kk 白金合金メッキ浴

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 017, no. 653 (E-1469), 3 December 1993 (1993-12-03) -& JP 05 217586 A (FUJI ELECTRIC CO LTD), 27 August 1993 (1993-08-27) *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 198 (C-1187), 7 April 1994 (1994-04-07) -& JP 06 000379 A (TANAKA KIKINZOKU KOGYO KK), 11 January 1994 (1994-01-11) *
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 13, 30 November 1998 (1998-11-30) -& JP 10 212592 A (TANAKA KIKINZOKU KOGYO KK), 11 August 1998 (1998-08-11) *
SHIM J ET AL: "Characteristics for electrocatalytic properties and hydrogen-oxygen adsorption of platinum ternary alloy catalysts in polymer electrolyte fuel cell" ELECTROCHIMICA ACTA, ELSEVIER SCIENCE PUBLISHERS, BARKING, GB, vol. 45, no. 12, February 2000 (2000-02), pages 1943-1951, XP004187014 ISSN: 0013-4686 *

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7241717B2 (en) 2003-10-23 2007-07-10 Cataler Corporation Cathode catalyst for fuel cell
EP1526592A1 (fr) * 2003-10-23 2005-04-27 Cataler Corporation Catalyseur catodique pour pile à combustble
US7736790B2 (en) 2004-12-06 2010-06-15 Honda Motor Co., Ltd. Platinum and tungsten containing electrocatalysts
US7435504B2 (en) 2005-08-25 2008-10-14 Honda Motor Co., Ltd. Platinum, tungsten, and nickel or zirconium containing electrocatalysts
WO2007024489A3 (fr) * 2005-08-25 2007-04-12 Honda Motor Co Ltd Electrocatalyseurs contenant du platine, du tungstene, et du nickel ou du zirconium
JP2009506500A (ja) * 2005-08-25 2009-02-12 本田技研工業株式会社 白金、タングステン、およびニッケルまたはジルコニウムを含有する電極触媒
US7695851B2 (en) 2005-08-25 2010-04-13 Honda Motor Co., Ltd. Platinum, tungsten and nickel containing electrocatalysts
WO2007024489A2 (fr) * 2005-08-25 2007-03-01 Honda Motor Co., Ltd. Electrocatalyseurs contenant du platine, du tungstene, et du nickel ou du zirconium
WO2007067546A2 (fr) * 2005-12-06 2007-06-14 Honda Motor Co., Ltd. Électrocatalyseurs contenant du platine et du tungstène
WO2007067546A3 (fr) * 2005-12-06 2007-09-13 Honda Motor Co Ltd Électrocatalyseurs contenant du platine et du tungstène
WO2020061468A1 (fr) 2018-09-21 2020-03-26 Deringer-Ney, Inc. Alliages à base de platine-nickel, produits, et procédés de fabrication et d'utilisation correspondants
JP2022501502A (ja) * 2018-09-21 2022-01-06 デリンジャー−ニー・インコーポレイテッドDeringer−Ney Inc. 白金−ニッケル基合金、製品、およびそれらを製造および使用する方法
EP3853390A4 (fr) * 2018-09-21 2022-11-23 Deringer-Ney, Inc. Alliages à base de platine-nickel, produits, et procédés de fabrication et d'utilisation correspondants
JP7463352B2 (ja) 2018-09-21 2024-04-08 デリンジャー－ニー・インコーポレイテッド 白金－ニッケル基合金、製品、およびそれらを製造および使用する方法

Also Published As

Publication number Publication date
AU2003213202A1 (en) 2003-09-09
WO2003071621A3 (fr) 2004-12-02

Similar Documents

Publication Publication Date Title
US7608560B2 (en) Platinum-titanium-tungsten fuel cell catalyst
US7811965B2 (en) Platinum-copper-nickel fuel cell catalyst
US7422994B2 (en) Platinum-copper-tungsten fuel cell catalyst
US6498121B1 (en) Platinum-ruthenium-palladium alloys for use as a fuel cell catalyst
US7700521B2 (en) Platinum-copper fuel cell catalyst
US7662740B2 (en) Platinum-chromium-copper/nickel fuel cell catalyst
US7101639B2 (en) Fuel cell electrocatalyst of Pt-Rh-Mo-Ni/Fe
US20070037696A1 (en) Platinum-palladium-titanium fuel cell catalyst
US20080166623A1 (en) Platinum-Nickel-Iron Fuel Cell Catalyst
US7479343B2 (en) Platinum-indium-iron/tungsten/manganese fuel cell electrocatalyst
US7635533B2 (en) Fuel cell electrocatalyst of Pt-Mn-Co
US8021798B2 (en) Fuel cell electrocatalyst of Pt-Zn-Ni/Fe
EP1479121B1 (fr) Electrocatalyseur pour une pile a combustible comprenant pt-ni-mn/fe
US20080044719A1 (en) Platinum-copper-titanium fuel cell catalyst
WO2003081702A2 (fr) Catalyseur au pt-rh-w/sn/cu/mo pour pile a combustible
WO2003071621A2 (fr) Electrocatalyseur de pile à combustible de pt-mo-ni/fe/sn/w
US20070054802A1 (en) Platinum-vanadium-iron fuel cell electrocatalyst
WO2000069009A9 (fr) Alliage de platinum-ruthenium-palladium-osmium destine a etre utilise comme catalyseur de pile a combustible
WO2004064181A2 (fr) Electrocatalyseur platine-ruthenium-cobalt

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC 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 OM PH PL PT RO RU SC SD SE SG SK SL TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT SE SI SK TR BF BJ CF CG CI CM GA GN GQ 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)
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP