Nanowire-based membrane electrode assemblies for fuel cells

• US 7,977,007 B2
• Filed: 09/19/2008
• Issued: 07/12/2011
• Est. Priority Date: 12/09/2004
• Status: Active Grant

• Current Assignee: ONED Material Incorporated
• Original Assignee: Nanosys Incorporated (Shoei Electronic Materials, Inc.)
• Inventors: Empedocles, Stephen A., Niu, Chunming, Parce, J. Wallace, Chow, Calvin Y. H.
• Primary Examiner(s): Kalafut; Stephen J.
• Application Number:
  US12/234,104
• Publication Number:
  US 20090017363A1
• Time in Patent Office: 1,026 Days
• Field of Search: 429/480, 429/481, 429/487, 429/524, 429/526, 429/532
• US Class Current: 429/487
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/881 Electrolytic membranes
• CPC Class Codes: H01M 4/8846 Impregnation
• CPC Class Codes: H01M 4/8853 Electrodeposition
• CPC Class Codes: H01M 4/8867 Vapour deposition
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 4/9075 Catalytic material supported on carriers, e.g. powder carriers H01M4/8807, H01M4/881, H01M4/8814, H01M4/925 take precedence
• CPC Class Codes: H01M 4/921 Alloys or mixtures with metallic elements
• CPC Class Codes: H01M 4/925 supported on carriers, e.g. powder carriers
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: H01M 8/023 Porous and characterised by the material
• CPC Class Codes: H01M 8/0232 Metals or alloys
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: H01M 8/0236 Glass; Ceramics; Cermets
• CPC Class Codes: H01M 8/0241 Composites
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1007 with both reactants being gaseous or vaporised H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1011 Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: H01M 8/1086 After-treatment of the membrane other than by polymerisation
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 977/762 : Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/948 : Energy storage/generating using nanostructure, e.g. fuel cell, battery

Abstract

The present invention discloses nanowires for use in a fuel cell comprising a metal catalyst deposited on a surface of the nanowires. A membrane electrode assembly for a fuel cell is disclosed which generally comprises a proton exchange membrane, an anode electrode, and a cathode electrode, wherein at least one or more of the anode electrode and cathode electrode comprise an interconnected network of the catalyst supported nanowires. Methods are also disclosed for preparing a membrane electrode assembly and fuel cell based upon an interconnected network of nanowires.

Claims

1. A nanostructured catalyst support for a membrane electrode assembly of a fuel cell comprising an interconnected network of nanowires each having a metal catalyst deposited thereon wherein the catalyst metal comprises nanoparticles having a diameter less than about 10 nm, wherein the nanowire network defines a plurality of pores between the nanowires in the network, wherein the plurality of pores have an effective pore size of less than about 10 microns.

2. The nanostructured catalyst support of claim 1, wherein the plurality of pores have an effective pore size of less than about 5 microns.

3. The nanostructured catalyst support of claim 1, wherein the plurality of pores have an effective pore size of less than about 1 microns.

4. The nanostructured catalyst support of claim 1, wherein the plurality of pores have an effective pore size of less than about 0.2 microns.

5. The nanostructured catalyst support of claim 1, wherein the plurality of pores have an effective pore size of between about 0.002 microns and 0.2 microns.

6. The nanostructured catalyst support of claim 1, wherein the catalyst metal comprises platinum.

7. The nanostructured catalyst support of claim 1, wherein the catalyst metal comprises platinum and ruthenium.

8. The nanostructured catalyst support of claim 1, wherein the catalyst metal is selected from the group comprising one or more of Pt, Au, Pd, Ru, Re, Rh, Os, Ir, Fe, Go, Ni, Cu, Ag, V, Cr, Mo, W and alloys or mixtures thereof

9. The nanostructured catalyst support of claim 1, wherein the catalyst metal comprises nanoparticles having a diameter between about 1 nm and 5 nm.

10. The nanostructured catalyst support of claim 1, wherein each nanowire in the network of nanowires is contacted by at least one or more other nanowires in the nanowire network.

11. The nanostructured catalyst support of claim 1, wherein each nanowire in the network of nanowires is physically connected to at least one or more other nanowires in the nanowire network.

12. The nanostructured catalyst support of claim 1, wherein the nanowires are made from conducting or semiconducting carbides, nitrides and oxides.

13. The nanostructured catalyst support of claim 1, wherein the nanowires comprise carbon.

14. The nanostructured catalyst support of claim 13, wherein the nanowires comprise carbon nanotubes.

15. The nanostructured catalyst support of claim 1, wherein the nanowires are selected from the group comprising Si, RuO₂, SiC, GaN, Ti0₂, SnO₂, WC_x, MoC_x, ZrC, WN_x, and MoN_x nanowires.

16. The nanostructured catalyst support of claim 1, further comprising a proton conducting polymer in contact with the nanowires.

17. The nanostructured catalyst support of claim 1, wherein the membrane electrode assembly is a component in a direct methanol fuel cell (DFMC).

18. The nanostructured catalyst support of claim 1, wherein the amount of deposited catalyst metal is about 10% to 85% by weight based on the total amount of catalyst metal and nanowire material.

19. The nanostructured catalyst support of claim 1, wherein the amount of deposited catalyst metal is about 20% to 40% by weight based on the total amount of catalyst metal and nanowire material.

20. The nanostructured catalyst support of claim 1, wherein the plurality of nanowires comprise a semiconductor material selected from group IV, group II-VI, group III-V semiconductors and alloys and mixtures thereof.

21. A membrane electrode assembly, comprising a proton exchange membrane, an anode electrode, and a cathode electrode, wherein at least one or more of the anode electrode and cathode electrode comprise an interconnected network of nanowires each comprising one or more metal catalyst nanoparticles having a diameter between about 1 and 10 nm deposited thereon, and wherein the nanowire network defines a plurality of pores between the nanowires in the network, wherein the plurality of pores have an effective pore size of less than about 10 microns.

22. A fuel cell comprising the membrane electrode assembly of claim 21.