Catalyst and electrode catalyst layer, membrane electrode assembly, and fuel cell using the catalyst

Patent metadata

Field	Value
Publication number	US-9947934-B2
Application number	US-201414786632-A
Country	US
Kind code	B2
Filing date	Apr 14, 2014
Priority date	Apr 25, 2013
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

The present invention has an object to provide a catalyst having excellent oxygen reduction reaction activity. The present invention relates to a catalyst comprising a catalyst support and a catalyst metal supported on the catalyst support, wherein a specific surface area of the catalyst per support weight is 715 m 2 /g support or more or a covering ratio of the catalyst metal with an electrolyte is less than 0.5, and an amount of an acidic group of the catalyst per support weight is 0.75 mmol/g support or less.

First claim

The invention claimed is:

1. A cathode catalyst layer for a fuel cell, comprising:
a cathode catalyst comprising a catalyst support and catalyst metal supported on the catalyst support,
wherein catalyst metal is supported inside mesopores having a radius of 1 nm or more of the catalyst support,
wherein a specific surface area of the cathode catalyst per support weight is 1200 m 2 /g support or more, and
wherein an amount of an acidic group of the cathode catalyst per support weight is 0.75 mmol/g support or less, and
an electrolyte,
wherein catalyst metal, which is present inside the mesopores, is not covered with the electrolyte.

2. The cathode catalyst layer according to claim 1 , further comprising:
catalyst metal covered with the electrolyte,
wherein a covering ratio of the catalyst metal covered with the electrolyte is less than 0.5.

3. The cathode catalyst layer according to claim 2 , wherein the covering ratio of the catalyst metal covered with the electrolyte is 0.4 or less.

4. The cathode catalyst layer according to claim 1 , wherein the support includes a metal oxide or carbon.

5. The cathode catalyst layer according to claim 1 , wherein the acidic group is at least one selected from the group consisting of a hydroxyl group, a lactone group, and a carboxyl group.

6. The cathode catalyst layer according to claim 1 , wherein the catalyst metal is platinum or includes platinum and a metal component other than platinum.

7. The cathode catalyst layer according to claim 1 , wherein an amount of the catalyst metal supported on the support is 50 wt % or less.

8. The cathode catalyst layer for the fuel cell set forth in claim 1 , wherein the amount of the acidic group of the cathode catalyst per support weight is 0.1 mmol/g support or more.

9. The cathode catalyst layer for the fuel cell set forth in claim 1 , wherein the specific surface area of the cathode catalyst per support weight is 1700 m 2 /g support or more.

10. A membrane electrode assembly for a fuel cell comprising the cathode catalyst layer for the fuel cell set forth in claim 1 .

11. A fuel cell comprising the membrane electrode assembly for the fuel cell set forth in claim 10 .

12. The fuel cell set forth in claim 11 , wherein the fuel cell is a polymer electrolyte fuel cell.

13. A method of manufacturing the cathode catalyst layer set forth in claim 1 , comprising:
supporting the catalyst metal on the catalyst support to obtain a catalyst powder; and
subjecting the catalyst powder to heat-treatment in a hydrogen atmosphere,
wherein the heat-treatment is carried out at a range of 900° C. to 1400° C. in temperature.

14. A cathode, comprising:
a cathode catalyst comprising a catalyst support and catalyst metal supported on the catalyst support,
wherein catalyst metal is supported inside mesopores having a radius of 1 nm or more of the catalyst support,
wherein a specific surface area of the cathode catalyst per support weight is 1700 m 2 /g support or more,
wherein an amount of an acidic group of the cathode catalyst per support weight is 0.75 mmol/g support or less, and
wherein catalyst metal, which is present inside the mesopores, is not covered with the electrolyte.

Assignees

• Nissan Motor
• Nippon Steel & Sumikin Chem Co

Inventors

• Akizuki Ken
• Ohma Atsushi
• Mashio Tetsuya
• Ono Yoshitaka
• Takahashi Shinichi

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/1004

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

• H01M4/925

  supported on carriers, e.g. powder carriers · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M4/926

  on carbon or graphite · CPC title