Processes for producing catalyst-layer-supporting substrate, catalyst-layer-supporting substrate, membrane electrode assembly, and fuel cell

Patent metadata

Field	Value
Publication number	US-9666875-B2
Application number	US-201414259476-A
Country	US
Kind code	B2
Filing date	Apr 23, 2014
Priority date	Jul 25, 2008
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A catalyst-layer-supporting substrate comprising a substrate supporting a catalyst layer; wherein the catalyst layer comprises two or more porous catalyst metal particle layers that are superposed alternately with (i) two or more intersticed layers comprising at least one element selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu; or (ii) two or more fibrous carbon layers having interstices among fibers of the fibrous carbon. A method for forming a catalyst-layer-supporting structure that comprises porous catalyst metal particle by removing a pore-forming metal from a mixture layer containing a pore-forming metal and a catalyst metal.

First claim

What is claimed is:

1. A catalyst-layer-supporting substrate comprising:
a substrate supporting a catalyst layer;
wherein the catalyst layer comprises
two or more porous catalyst metal particle layers having a porosity ranging from 20% to 90% that are superposed alternately with
(i) two or more intersticed layers comprising at least one element selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu; or
(ii) two or more fibrous-carbon layers having interstices among fibers of the fibrous carbon, wherein for (ii) the two or more porous catalyst metal particle layers having a porosity ranging from 20% to 90% are produced by removing a pore-forming metal from a mixture layer containing a pore-forming metal and the catalyst metal.

2. The catalyst-layer-supporting substrate according to claim 1 that comprises (i) two or more intersticed layers comprising at least one element selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu, wherein said intersticed layers have a thickness ranging from 10 nm to 500 nm.

3. The catalyst-layer-supporting substrate according to claim 1 that comprises (ii) two or more fibrous-carbon layers having interstices among fibers of the fibrous carbon, wherein said fibrous carbon layers comprise carbon nanofibers, carbon nanotubes and/or carbon black.

4. The catalyst-layer-supporting substrate according to claim 1 , comprising catalyst metal particle layers having a thickness of from 10 nm to 500 nm per layer and comprising fibrous-carbon layers having interstices among fibers of the fibrous carbon having a thickness of from 500 nm to 5,000 nm per layer.

5. The catalyst-layer-supporting substrate of claim 1 , wherein the catalyst metal is at least one noble-metal element or an alloy of at least one noble-metal element and at least one element selected from the group consisting of W, Hf, Si, Mo, Ta, Ti, Zr Ni, Co, Nb, V, and Cr.

6. The catalyst-layer-supporting substrate of claim 1 , wherein the porous catalyst metal particle layers comprise at least one noble-metal catalyst selected from the group consisting of Pt, Ru, Rh, Os, Ir, Pd and Au.

7. The catalyst-layer-supporting substrate of claim 1 , wherein the porous catalyst metal particle layers comprise at least one noble-metal catalyst having the formula Pt y Ru z T 1-y-z , wherein y satisfies 0.2≦y≦0.8 and z satisfies 0≦z≦0.5 and T is at least one of W, Hf, Si, Mo, Ta, Ti, Zr Ni, Co, Nb, V and Cr.

8. The catalyst-layer-supporting substrate of claim 1 , wherein the porous catalyst metal particle layers comprise at least one noble-metal catalyst having the formula Pt u T 1-u , wherein u satisfies 0.2≦u≦0.75 and T is at least one of W, Hf, Si, Mo, Ta, Ti, Zr, Ni, Co, Nb, V and Cr.

9. The catalyst-layer-supporting substrate of claim 1 , wherein the porous catalyst metal particle layers comprise at least one oxide catalyst, nitride catalyst or carbide catalyst.

10. The catalyst-layer-supporting substrate of claim 1 , wherein the catalyst metal particle layers are made from a first pore-forming metal that is (i) Mn alone or Fe alone or (ii) the first pore-forming metal is an alloy containing at least one metal selected from the group consisting of Co, Ni, Zn, Sn, and Al and at least one metal selected from the group consisting of Mn and Fe.

11. The catalyst-layer-supporting substrate of claim 1 , wherein the pore-forming metal in (ii) comprises at least one metal selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu.

12. The catalyst-layer-supporting substrate of claim 1 that comprises at least one electroconductive substrate material selected from the group consisting of a porous paper containing conductive carbon fibers and a ceramic porous substrate having electrical conductivity.

13. The catalyst-layer-supporting substrate of claim 1 that comprises at least one proton conductive substrate material selected from the group consisting of a fluorochemical electrolyte membrane, hydrocarbon type electrolyte membranes and composition oxides having the nature of an ultrastrong acid.

14. The catalyst-layer-supporting substrate of claim 1 that is made by a process comprising:
a layer superposition step comprising a first step in which at least one first pore-forming metal and at least one catalyst metal are sputtered or vapor-deposited on a substrate to form a mixture layer containing the first pore-forming metal and the catalyst metal and
a second step in which at least one second pore-forming metal is sputtered or vapor-deposited on the mixture layer to form an interlayer containing the second pore-forming metal, the first step and the second step being alternately conducted repeatedly two or more times to thereby form a multilayer structure containing layers each of which is the mixture layer and layers each of which is the interlayer; and
a pore formation step in which after the layer superposition step, the first and second pore-forming metals in the multilayer structure are dissolved away to obtain a catalyst layer.

15. The catalyst-layer-supporting substrate of claim 1 that is made by a process comprising:
a layer superposition step comprising a first step in which at least one first pore-forming metal and at least one catalyst metal are sputtered or vapor-deposited on a substrate to form a mixture layer containing the first pore-forming metal and the catalyst metal and
a second step in which fibrous carbon is synthesized on the mixture layer to form an interlayer containing the fibrous carbon,
the first step and the second step being alternately conducted repeatedly two or more times to thereby form a multilayer structure containing layers each of which is the mixture layer and layers each of which is the interlayer; and
a pore formation step in which after the layer superposition step, the multilayer structure is subjected to a pore formation treatment to dissolve away the first pore-forming metal and thereby obtain a catalyst layer.

16. A membrane electrode assembly, comprising:
an anode-catalyst-layer-supporting substrate comprising a first substrate and an anode catalyst layer formed on the first substrate, the anode catalyst layer comprising two or more porous anode catalyst metal particle layers having a porosity ranging from 20% to 90% that are superposed alternately with two or more intersticed layers comprising (i) at least one element selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu or (ii) fibrous-carbon layers, wherein for (ii) the two or more porous catalyst metal particle layers having a porosity ranging from 20% to 90% are produced by removing a pore-forming metal from a mixture layer containing a pore-forming metal and the catalyst metal,
a cathode-catalyst-layer-supporting substrate comprising a second substrate and a cathode catalyst layer formed on the second substrate, the cathode catalyst layer comprising two or more porous cathode catalyst metal particle layers having a porosity ranging from 20% to 90% that are superposed alternately with two or more intersticed layers comprising (i) at least one element selected from the group consisting of Mn, Fe, Co, Ni, Zn, Sn, Al, and Cu or (ii) fibrous-carbon layers having interstices among the fibers of the fibrous carbon, wherein for (ii) the two or more porous catalyst metal particle layers having a porosity ranging from 20% to 90% are produced by removing a pore-forming metal from a mixture layer containing a pore-forming metal and the catalyst metal, and
a proton-conductive membrane sandwiched between the anode catalyst layer and the cathode catalyst layer.

Assignees

• Toshiba Kk

Inventors

• Wu Mei
• Kobayashi Tsuyoshi
• Yamazaki Mutsuki
• Nakano Yoshihiko

Classifications

• Y02E60/50

  Fuel cells · CPC title

• Y02P70/56

  Cross-Sectional Technologies · mapped topic

• H01M4/9083 Primary

  on carbon or graphite · CPC title

• H01M4/8814

  Temporary supports, e.g. decal · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title