Low platinum fuel cell catalysts and method for preparing the same
View Patent ↗This invention provides novel fuel cell catalysts comprising new series of catalytically active thin-film metal alloys with low platinum concentration supported on nanostructured materials (nanoparticles). In certain embodiments, an integrated gas-diffusion/electrode/catalyst layer can be prepared by processing catalyst thin films and nanoparticales 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.
1. A method of preparing a fuel cell element, said method comprising:
providing a plurality of fibers and/or a porous electrode material;
depositing a nanoparticle catalyst on said plurality of fibers and/or porous electrode material;
forming nanoparticles on said plurality of fibers and/or porous electrode material using said nanoparticles catalyst;
forming a catalytically active layer comprising a substantially continuous thin film on said nanoparticles thereby forming a fuel cell element comprising a plurality of fibers bearing nanoparticles partially or fully coated with a catalytically active thin film;
wherein said thin film comprises an alloy having the formula:
Pt x V y Co z Ni 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; and
x+y+z+w=1.
2. The method of claim 1 , wherein said plurality of fibers comprises a plurality of carbon fibers.
3. The method of claim 2 , wherein said plurality of carbon fibers comprise a porous electrode.
4. The method of claim 2 wherein said plurality of fibers comprise a carbon fiber paper.
5. The method of claim 1 , wherein said nanoparticle catalyst is a carbon nanotube catalyst and said nanoparticles are carbon nanotubes.
6. The method of claim 5 , wherein said nanoparticles are formed by chemical vapor deposition (CVD) or said depositing a nanoparticle catalyst comprises depositing said catalyst on said fibers by chemical vapor deposition (CVD).
7. The method of claim 5 , wherein said nanotubes have a length less than 50 μm and a width less than 100 nm.
8. The method of claim 5 , wherein said nanotubes have a diameter of 50 nm to 100 nm.
9. The method of claim 1 , wherein said thin film partially covers the nanoparticles.
10. The method of claim 1 , wherein the nanoparticles are fully coated with said thin film.
11. The method of claim 1 , wherein said thin film ranges in thickness from 1 to 1000 angstroms.
12. The method of claim 10 , wherein said thin film ranges in thickness from 5 to 500 angstroms.
13. The method of claim 10 , wherein said thin film ranges in thickness from 5 to 100 angstroms.
14. The method of claim 1 , wherein platinum comprises from 6% up to 50% (mole ratio or atomic percentage) of said alloy.
15. The method of claim 14 , wherein platinum comprises up to 12% (mole ratio or atomic percentage) of said alloy.
16. The method of claim 13 , wherein said alloy contains platinum, vanadium, nickel, and copper.
17. The method of claim 1 , wherein x is 0.12.
18. The method of claim 1 , wherein x is 0.12, y is 0.07, z is 0.56, and w is 0.25.
19. The method of claim 1 , wherein:
said providing a plurality of fibers and/or a porous electrode material comprises providing a carbon fiber paper;
said depositing a nanoparticle catalyst comprises depositing said catalyst by chemical vapor deposition;
said forming nanoparticles comprises forming carbon nanotubes; and
said forming a catalytically active layer comprising depositing a substantially continuous thin film comprising platinum or a platinum alloy.