Method for producing a supported catalyst material for a fuel cell

Patent metadata

Field	Value
Publication number	US-11489167-B2
Application number	US-201716313874-A
Country	US
Kind code	B2
Filing date	Jun 26, 2017
Priority date	Jun 30, 2016
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

The invention relates to a method for producing a supported catalyst material for a fuel-cell electrode, as well as a catalyst material that can be produced using said method. In the method, first, a carbide-forming substance is deposited from the gas phase onto the carbon-based carrier material to produce a carbide-containing layer and, then, a catalytically-active precious metal or an alloy thereof from the gas phase is deposited to form a catalytic layer. By chemical reaction of the carbide-forming substance with the carbon, very stable carbide bonds are formed at the interface, while an alloy phase of the two forms at the interface between carbide-forming substance and precious metal. Overall, a very stable adhesion of the catalytic precious metal to the substrate results, whereby degradation effects are reduced, and the life of the material is extended.

First claim

The invention claimed is:

1. A method for manufacturing a supported catalyst material for a fuel-cell electrode, comprising:
forming a carbide-containing layer by depositing a carbide-forming substance from a gas phase onto an electrically conductive carbon-based carrier material, the carbide-forming substance reacting with carbon of the carrier material; and
forming a catalytic layer by depositing a catalytically-active precious metal or an alloy of such a precious metal from the gas phase;
wherein the depositing of the carbide-forming substance and the depositing of the catalytically-active precious metal or the alloy of the precious metal is in a time-overlapping manner, producing a gradual enrichment of the catalytically-active precious metal or its alloy.

2. The method according to claim 1 , wherein the carbide-forming substance is selected from the group comprising titanium, zirconium, hafnium, tungsten, molybdenum, boron, vanadium, aluminum, scandium, yttrium, silicon, chromium, and nickel, or a mixture of these.

3. The method according to claim 1 , wherein the carbide-containing layer has an average thickness in the range of 1 to 50 atomic layers.

4. The method according to claim 1 , wherein the catalytically-active precious metal or its alloy comprises platinum, ruthenium, rhodium, palladium, osmium, iridium, or an alloy of these metals.

5. The method according to claim 1 , further comprising forming defect sites on a surface of the carbon-based carrier material before depositing the carbide-forming substance.

6. The method according to claim 1 , wherein, after depositing the carbide-forming substance and before depositing the catalytically-active precious metal or its alloy, a diffusion barrier layer is deposited, selected from the group comprising gold, palladium, ruthenium, tungsten, osmium, rhodium, and iridium, or a mixture or alloy thereof.

7. A supported catalyst material for a fuel-cell electrode comprising:
an electrically-conductive, carbon-based carrier material;
a carbide-containing layer on the carrier material; and
a catalytic layer of a catalytically-active precious metal or an alloy of such on the surface of the carbide-containing layer,
wherein the carbide-containing layer and the catalytic layer are produced by a method comprising depositing a carbide-forming substance and depositing the catalytically-active precious metal or the alloy thereof in a time-overlapping manner, thereby producing a gradual enrichment of the catalytically-active precious metal or its alloy at the surface of the carbide-containing layer.

8. An electrode structure for a fuel-cell, comprising:
a flat carrier, selected from a polymer electrolyte membrane and a gas-permeable, electrically-conductive substrate; and
a catalytic coating comprising: an electrically-conductive, carbon-based carrier material; a carbide-containing layer on the carrier material; and a catalytic layer of a catalytically-active precious metal or an alloy of such on the surface of the carbide-containing layer, wherein said catalytic coating is arranged on at least one flat side of the carrier,
wherein the carbide-containing layer and the catalytic layer are produced by a method comprising depositing a carbide-forming substance and depositing the catalytically-active precious metal or the alloy thereof in a time-overlapping manner, thereby producing a gradual enrichment of the catalytically-active precious metal or its alloy at the surface of the carbide-containing layer.

9. The method according to claim 1 , further comprising forming covalent bonds between carbon atoms of a surface of the carbon-based carrier material and chemical groups that promote carbide formation before depositing the carbide-forming sub stance.

10. The supported catalyst material according to claim 7 , wherein the carbide-containing layer has an average thickness in the range of 1 to 50 atomic layers.

11. The supported catalyst material according to claim 7 , wherein the carbide-containing layer has an average thickness in the range of 1 to 20 atomic layers.

12. The supported catalyst material according to claim 7 , wherein a surface of the carbon-based carrier material comprises defect sites.

13. The supported catalyst material according to claim 7 , wherein a surface of the carbon-based carrier material comprises carbon atoms covalently bonded to chemical groups that promote carbide formation.

14. The supported catalyst material according to claim 7 , wherein the catalytically-active precious metal or its alloy comprises platinum, ruthenium, rhodium, palladium, osmium, iridium, or an alloy of these metals.

15. The electrode structure according to claim 8 , wherein the carbide-containing layer has an average thickness in the range of 1 to 50 atomic layers.

16. The electrode structure according to claim 8 , wherein the surface of the carbide-containing layer comprises defect sites.

17. The electrode structure according to claim 8 , wherein the surface of the carbon-based carrier material comprises carbon atoms covalently bonded to chemical groups that promote carbide formation.

18. The electrode structure according to claim 8 , wherein the catalytically-active precious metal or its alloy comprises platinum, ruthenium, rhodium, palladium, osmium, iridium, or an alloy of these metals.

19. The method according to claim 1 , wherein producing a gradual enrichment of the catalytically-active precious metal or its alloy comprises changing the relative proportions of the carbide-forming substance and the precious metal or alloy of such a precious metal in the gas phase continuously during depositing of the carbide-forming substance and the depositing of the catalytically-active precious metal or the alloy of the precious metal.

Assignees

• Volkswagen Ag
• Audi Ag

Inventors

• Graf Tanja
• Schladt Thomas

Classifications

• H01M4/8657

  layered · CPC title

• H01M4/921

  Alloys or mixtures with metallic elements · CPC title

• H01M4/8817 Primary

  Treatment of supports before application of the catalytic active composition (coated porous composites H01M8/0245) · CPC title

• H01M4/926 Primary

  on carbon or graphite · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title