Durable platinum/multi-walled carbon nanotube catalysts

Patent metadata

Field	Value
Publication number	US-9331341-B2
Application number	US-201113635073-A
Country	US
Kind code	B2
Filing date	Mar 17, 2011
Priority date	Mar 17, 2010
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

Platinum nanocatalysts on multi-walled carbon nanotubes (MWCNTs) functionalized with citric acid (CA) are disclosed, along with methods for the synthesis thereof.

First claim

What is claimed is:

1. A method for preparing a fuel cell catalyst, the method comprising contacting a surface modified multiwalled carbon nanotube with a platinum containing precursor disposed in an organic solvent; wherein the platinum containing precursor is prepared from an aqueous solution comprising a platinum containing compound and a phase transfer catalyst.

2. The method of claim 1 , further comprising contacting a multiwalled carbon nanotube with an acid to produce the surface modified multiwalled carbon nanotube.

3. The method of claim 2 , wherein the acid comprises citric acid.

4. The method of claim 1 , wherein after contacting with a platinum containing precursor, the surface modified multiwalled carbon nanotube is contacted with a reducing agent.

5. The method of claim 4 , wherein the reducing agent comprises one or more of sodium formate, formic acid, sodium borohydride, hydrogen, hydrazine, hydroxyl amine, or a combination thereof.

6. The method of claim 4 , wherein the surface modified multiwalled carbon nanotube is further contacted with a capping agent.

7. The method of claim 6 , wherein the surface modified multiwalled carbon nanotube is contacted substantially simultaneously with the reducing agent and the capping agent.

8. The method of claim 6 , wherein the capping agent comprises a thiol endgroup.

9. The method of claim 6 , wherein the capping agent comprises an alkanethiol.

10. The method of claim 6 , further comprising heat treating the multiwalled carbon nanotube after contacting with the platinum containing precursor.

11. The method of claim 10 , wherein after heat treating, no or substantially no capping agent is present on the multiwalled carbon nanotube.

12. The method of claim 1 , wherein the surface modified multiwalled carbon nanotube has an external diameter of from about 10 nm to about 50 nm.

13. The method of claim 1 , wherein the surface modified multiwalled carbon nanotube has an ash content of less than about 3 wt. %.

14. The method of claim 1 , wherein the platinum containing precursor comprises PtCl 6 2− .

15. The method of claim 1 , wherein the phase transfer catalyst comprises tetraoctylammonium bromide.

16. A multiwalled carbon nanotube supported platinum catalyst comprising:
a plurality of platinum nanoparticles having an average particle size of from about 1 nm to about 3 nm; and an electrochemical surface area of at least about 84 m 2 /g.

17. A membrane electrode assembly comprising the multiwalled carbon nanotube supported platinum catalyst of claim 16 .

18. A PEM fuel cell comprising the multiwalled carbon nanotube supported platinum catalyst of claim 16 .

19. The multiwalled carbon nanotube supported platinum catalyst of claim 16 , having an initial electrochemical surface area prior to operation in a fuel cell when disposed in a membrane electrode assembly, and being capable of maintaining at least about 90% of the initial electrochemical surface area after 100 hours of operation at 80° C., ambient pressure, and 0.4 V load.

Assignees

• Kannan Arunachala
• Lin Jiefeng
• Univ Arizona

Inventors

• Kannan Arunachala
• Lin Jiefeng

Classifications

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M4/926

  on carbon or graphite · CPC title

• H01M4/92 Primary

  Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence) · CPC title