Nanostructured catalyst supports

Abstract

The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

What is claimed is: 
     
       1. A catalyst support for a membrane electrode assembly of a fuel cell, comprising one or more SiC nanostructures, wherein the SiC nanostructures have at least one metal catalyst disposed thereon, wherein the SiC nanostructures comprise SiC nanopowder, wherein the SiC nanopowder is cross-linked by graphene sheets. 
     
     
       2. The catalyst support of  claim 1 , further comprising one or more nanowires comprising RuO 2 , SiC, GaN, TiO 2 , SnO 2 , WC x , MoC x , ZrC, WN x , or MoN x . 
     
     
       3. The catalyst support of  claim 1 , wherein the catalyst metal comprises one or more of Pt, Au, Pd, Ru, Re, Rh, Os, Ir, Fe, Co, Ni, Cu, Ag, V, Cr, Mo, W, and alloys or mixtures thereof. 
     
     
       4. The catalyst support of  claim 1 , wherein the catalyst metal comprises nanoparticles having a diameter less than about 10 nm. 
     
     
       5. The catalyst support of  claim 1 , further comprising a proton conducting polymer in contact with the SiC nanopowder. 
     
     
       6. The catalyst support of  claim 1 , wherein the membrane electrode assembly is a component in a hydrogen fuel cell or a direct methanol fuel cell (DMFC). 
     
     
       7. The catalyst support of  claim 1 , wherein the catalyst metal comprises PtRu nanoparticles. 
     
     
       8. A catalyst support for a membrane electrode assembly of a fuel cell, comprising one or more SiC nanostructures, wherein the SiC nanostructures have at least one metal catalyst disposed thereon, wherein the SiC nanostructures comprise a composite of SiC nanopowder and SiC nanowires, and wherein the nanopowder and the nanowires are cross-linked by graphene sheets. 
     
     
       9. A catalyst support for a membrane electrode assembly of a fuel cell comprising a composite of SiC nanopowder and inorganic nanowires, wherein at least one of the SiC nanopowder and the inorganic nanowires have at least one metal catalyst disposed thereon, and wherein the SiC nanopowder and the inorganic nanowires are cross-linked by graphene sheets. 
     
     
       10. The catalyst support of  claim 9 , wherein the nanowires comprise RuO 2 , SiC, GaN, TiO 2 , SnO 2 , WC x , MoC x , ZrC, WN x , or MoN x  nanowires. 
     
     
       11. The catalyst support of  claim 9 , wherein the catalyst metal comprises one or more of Pt, Au, Pd, Ru, Re, Rh, as, Ir, Fe, Co, Ni, Cu, Ag, V, Cr, Mo, W, and alloys or mixtures thereof. 
     
     
       12. The catalyst support of chum  9 , wherein the catalyst metal comprises nanoparticles having a diameter less than about 10 nm. 
     
     
       13. The catalyst support of  claim 9 , further comprising a proton conducting polymer in contact with the SiC nanopowder and nanowires. 
     
     
       14. The catalyst support of  claim 9 , wherein the membrane electrode assembly is a component in a hydrogen fuel cell or a direct methanol fuel cell (DMFC). 
     
     
       15. The catalyst support of  claim 9 , wherein the catalyst metal comprises Pt nanoparticles. 
     
     
       16. An electrochemical cell comprising:
 a support structure comprising a plurality of nanowires grown on and attached directly to graphite, carbon, or a carbon composite;   wherein the nanowires form a porous structure comprising an interconnected network of nanowires cross-linked by graphene sheets; and   wherein the nanowires comprise a silicon-comprising core and at least one carbon-comprising outer shell.   
     
     
       17. The electrochemical cell of claim 16, wherein the electrochemical cell is a fuel cell. 
     
     
       18. The electrochemical cell of claim 16, wherein the electrochemical cell is a battery. 
     
     
       19. The electrochemical cell of claim 18, further comprising: an anode that comprises the support structure. 
     
     
       20. The electrochemical cell of claim 18, further comprising: a cathode that comprises the support structure. 
     
     
       21. The electrochemical cell of claim 16, further comprising an electrolyte. 
     
     
       22. The electrochemical cell of claim 21, wherein the electrolyte comprises a polymer. 
     
     
       23. The electrochemical cell of claim 22, wherein the polymer electrolyte comprises polyethylene oxide. 
     
     
       24. The electrochemical cell of claim 21, wherein the electrolyte comprises an organic additive. 
     
     
       25. The electrochemical cell of claim 16, wherein the plurality of nanowires have one or more metal catalyst disposed thereon, the catalyst metal comprising one or more of Pt, Au, Pd, Ru, Re, Rh, Os, Ir, Fe, Co, Ni, Cu, Ag, V, Cr, Mo, W, and alloys or mixtures thereof. 
     
     
       26. The electrochemical cell of claim 16, wherein the electrochemical cell is a lithium-ion battery comprising an anode comprising the support structure. 
     
     
       27. The electrochemical cell of claim 16, wherein the core comprises doped silicon. 
     
     
       28. The electrochemical cell of claim 16, wherein the porous structure comprises pores having size greater than about 30 nm and less than about 200 nm in diameter. 
     
     
       29. The electrochemical cell of claim 16, wherein the plurality of nanowires have one or more metal catalyst disposed thereon, the metal catalyst comprising nanoparticles between about 1 nm and 50 nm in diameter.