Low platinum fuel cells, catalysts, and method for preparing the same

• US 8,211,593 B2
• Filed: 12/15/2005
• Issued: 07/03/2012
• Est. Priority Date: 09/08/2003
• Status: Expired due to Fees

• Current Assignee: Intematix Corporation
• Original Assignee: Intematix Corporation
• Inventors: Gu, Tao, Omstead, Thomas R., Dong, Yi, Li, Yi-Qun, Wang, Ning
• Primary Examiner(s): Cantelmo, Gregg
• Application Number:
  US11/303,476
• Publication Number:
  US 20060172179A1
• Time in Patent Office: 2,392 Days
• Field of Search: 428/408, 420/451, 427/115, 429/30, 429 40- 42, 429/487, 429/524, 429/527, 977/948, 502/102, 502/325, 502/326
• US Class Current: 429/524
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01B 1/04 mainly consisting of carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H01B 1/122 Ionic conductors
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 4/8825 Methods for deposition of the catalytic active composition
• CPC Class Codes: H01M 4/8892 Impregnation or coating of the catalyst layer, e.g. by an ionomer
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 4/9083 on carbon or graphite
• CPC Class Codes: H01M 4/921 Alloys or mixtures with metallic elements
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

This invention provides novel fuel cell electrodes and catalysts comprising a series of catalytically active thin-film metal alloys with low platinum concentration supported on nanostructured materials (nanoparticles). Processing of the electrodes and catalysts can include electrodeposition methods, and high-pressure coating techniques. In certain embodiments, an integrated gas-diffusion/electrode/catalyst layer can be prepared by processing catalyst thin films and nanoparticles into gas-diffusion media such as Toray or SGL carbon fiber papers. The catalysts can be placed in contact with an electrolyte membrane for PEM fuel cell applications.

Claims

1. A composition comprising a substrate bearing nanoparticles, wherein the nanoparticles are coated with an ionomer, wherein the nanoparticles are coated with a substantially continuous thin film comprising a platinum alloy, and wherein the alloy contains platinum, vanadium, nickel, and cobalt.

2. The composition of claim 1, wherein the substrate comprises a plurality of conductive fibers.

3. The composition of claim 1, wherein the ionomer comprises a perfluorocarbonsulfonic acid ionomer.

4. The composition of claim 2, wherein the conductive fibers comprise carbon fibers.

5. The composition of claim 1, wherein the nanoparticles are selected from the group consisting of:

nanotubes, nanofibers, nanohorns, nanopowders, nanospheres, and quantum dots.

6. The composition of claim 1, wherein the nanoparticles comprise carbon nanotubes.

7. The composition of claim 2, wherein the plurality of conductive fibers comprise a porous electrode.

8. The composition of claim 4, wherein the carbon fibers comprise a porous electrode.

9. The composition of claim 4, wherein the carbon fibers comprise a carbon paper, a carbon cloth or a carbon-impregnated polymer.

10. The composition of claim 2, wherein the plurality of conductive fibers comprise a porous metal sheet.

11. The composition of claim 6, wherein the carbon nanotubes are seeded with one or more catalysts comprising one or more materials selected from the group consisting of Co, Ni, V, Cr, Pt, Ru, Mo, W, Ta, and Zr.

12. The composition of claim 6, wherein the carbon nanotubes are seeded with one or more catalysts selected from the group consisting of Fe_xNi_yCo_1-x-y where 0≦

x≦

1 and 0≦

y≦

1, Co_1-xMo_x where 0≦

x≦

0.3, Co_1-x-yNi_xMo_y where 0.1≦

x≦

0.7 and 0≦

y≦

0.3, Co_1-x-y-zNi_xV_yCr_z where 0≦

x≦

0.7, 0≦

y≦

0.2 and 0≦

z≦

0.2, Ni_1-x-yMo_xAl_y where 0≦

x≦

0.2 and 0≦

y≦

0.2, and Co_1-x-yNi_xAl_y where 0≦

x≦

0.7 and 0≦

y≦

0.2.

13. The composition of claim 6, wherein the carbon nanotubes are seeded with one or more catalysts selected from the group consisting of:

Co_8.8Mo_1.2, CO_2.2Ni_5.6Mo_2.2, Co_5.7Ni_2.1V_1.1Cr_1.1, Ni_8.0Mo_1.0Al_1.0, and Co_6.4Ni_2.4Al_1.2.

14. The composition of claim 6, wherein the nanoparticles are nanotubes having a length less than 50 μ

m and a diameter less than about 500 nm.

15. The composition of claim 6, wherein the nanoparticles are nanotubes having a diameter in the range from about 1 nm to about 100 nm.

16. The composition of claim 1, wherein the thin film partially covers the nanoparticles.

17. The composition of claim 1, wherein the nanoparticles are fully coated with the thin film.

18. The composition of claim 1, wherein the thin film ranges in thickness from about 1 to about 1000 angstroms.

19. The composition of claim 18, wherein the thin film ranges in thickness from about 5 to about 500 angstroms.

20. The composition of claim 18, wherein the thin film ranges in thickness from about 5 to about 100 angstroms.

22. The composition of claim 20, wherein the thin film alloy further comprises and one or more metals selected from the group consisting of Mo, Ta, W, and Zr.

23. The composition of claim 22, wherein platinum comprises from about 12% up to about 99% mole ratio or atomic percentage of the alloy.

24. The composition of claim 22, wherein platinum comprises up to about 50% mole ratio or atomic percentage of the alloy.

25. The composition of claim 22, wherein the thin film comprises an alloy having the formula:

Pt_xV_yCo_zNi_w

wherein;

x is greater than 0.06 and less than 1;

y, z, and w are independently greater than zero and less than 1;

x+y+z+w=1.

26. The composition of claim 25, wherein x is 0.12.

27. The composition of claim 25, wherein x is 0.12, y is 0.07, z is 0.56, and w is 0.25.

21. A composition comprising a substrate bearing nanoparticles, wherein the nanoparticles are coated with an ionomer, wherein the nanoparticles are coated with a non-continuous thin film comprising a platinum alloy, and wherein the thin film comprises islands ranging in thickness from about 5 to about 100 angstroms and ranging in area from about 1 to 10⁴ nm².