Catalyst for fuel cells and method for producing the same

Patent metadata

Field	Value
Publication number	US-2016049664-A1
Application number	US-201314784115-A
Country	US
Kind code	A1
Filing date	Apr 18, 2013
Priority date	Apr 18, 2013
Publication date	Feb 18, 2016
Grant date	—

Abstract

The present invention is to provide a catalyst for fuel cells, which is able to inhibit gas diffusion resistance and shows high IV characteristics far more than conventional fuel cell catalysts, and a method for producing the catalyst. Disclosed is a catalyst for fuel cells, comprising fine catalyst particles, each of which comprises a palladium-containing particle and an outermost layer containing platinum and covering the palladium-containing particle, and a carrier on which the fine catalyst particles are supported, wherein the catalyst for fuel cells satisfies 0.9×S1≦S2 in which S1 is a BET specific surface area of a material for the carrier, and S2 is a BET specific surface area of the carrier in the catalyst for fuel cells.

First claim

1 . A catalyst for fuel cells, comprising fine catalyst particles, each of which comprises a palladium-containing particle and an outermost layer containing platinum and covering the palladium-containing particle, and a carrier on which the fine catalyst particles are supported,
wherein the catalyst for fuel cells satisfies 0.9×S1≦S2 in which S1 is a BET specific surface area of a material for the carrier, and S2 is a BET specific surface area of the carrier in the catalyst for fuel cells.

2 . The catalyst for fuel cells according to claim 1 , wherein the material for the carrier is a carbonaceous material.

3 . The catalyst for fuel cells according to claim 1 , wherein the catalyst has a mass activity of 450 (A/g Pt ) or more and a specific activity of 4.0 (A/m 2 ) or more.

4 . A method for producing a catalyst for fuel cells, the catalyst comprising fine catalyst particles, each of which comprises a palladium-containing particle and an outermost layer containing platinum and covering the palladium-containing particle, and a carrier on which the fine catalyst particles are supported,
wherein the method comprises:
preparing a carrier on which palladium-containing particles are supported;
covering the palladium-containing particles with a monatomic layer;
synthesizing the fine catalyst particles by substituting the monatomic layer with the outermost layer containing platinum in the presence of an additive; and
washing a catalyst precursor in which the fine catalyst particles are supported on the carrier with water, and
wherein a ratio of the total mass of the additive used for the synthesis of the fine catalyst particles and a derivative thereof, both of which remain in the catalyst for fuel cells after the washing, to a total mass of the additive is 2.5% by mass or less.

5 . The method for producing a catalyst for fuel cells according to claim 4 , wherein the catalyst precursor is dispersed and washed in water when it is washed with water.

6 . The method for producing a catalyst for fuel cells according to claim 4 , wherein a temperature of the water used for the washing is 30° C. or more and less than 100° C.

7 . The method for producing a catalyst for fuel cells according to claim 4 , wherein the additive is at least one surfactant selected from the group consisting of citric acid and ethylenediaminetetraacetic acid (EDTA), and sodium salts and potassium salts thereof.

8 . The method for producing a catalyst for fuel cells according to claim 4 , wherein an acid is further used when the monatomic layer is substituted with the outermost layer.

9 . The method for producing a catalyst for fuel cells according to claim 4 , wherein, when the carrier on which the palladium-containing particles are supported is prepared, the carrier is subjected to an acid treatment.

10 . A fuel cell comprising a unit cell, which comprises a membrane electrode assembly in which an anode electrode comprising at least an anode catalyst layer is disposed on one side of a polyelectrolyte membrane and a cathode electrode comprising at least a cathode catalyst layer is disposed on another side of the polyelectrolyte membrane,
wherein the catalyst for fuel cells defined by claim 1 is contained in at least any one of the anode catalyst layer and the cathode catalyst layer.

11 . A fuel cell comprising a unit cell, which comprises a membrane electrode assembly in which an anode electrode comprising at least an anode catalyst layer is disposed on one side of a polyelectrolyte membrane and a cathode electrode comprising at least a cathode catalyst layer is disposed on another side of the polyelectrolyte membrane,
wherein a catalyst for fuel cells produced by the production method defined by claim 4 is contained in at least any one of the anode catalyst layer and the cathode catalyst layer.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kaneko Keiichi
• Taniguchi Takumi
• Adachi Makoto
• Yamada Mayumi

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M4/926 Primary

  on carbon or graphite · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• H01M4/8825

  Methods for deposition of the catalytic active composition · CPC title

• H01M4/8878

  Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body · CPC title