Catalyst

Patent metadata

Field	Value
Publication number	US-2016104898-A1
Application number	US-201414891042-A
Country	US
Kind code	A1
Filing date	May 14, 2014
Priority date	May 14, 2013
Publication date	Apr 14, 2016
Grant date	—

Abstract

A de-alloyed catalyst of formula PtXY, wherein X is selected from the group consisting of Ni, Co and Cr; and Y is selected from the group consisting of Zn, Al, Sn, Be, Pb, Ga, V, In, Y, Sr and Ti; characterised in that the total atomic composition relative to Pt of X and Y at the surface of the de-alloyed catalyst as determined from X-ray photoelectron spectroscopy is between 20 and 99% lower than the total atomic composition relative to Pt of X and Y in the bulk of the de-alloyed catalyst is disclosed.

First claim

1 - 18 . (canceled)

19 . A de-alloyed catalyst of formula PtXY, wherein X is selected from the group consisting of Ni, Co and Cr; and Y is selected from the group consisting of Zn, Al, Sn, Be, Pb, Ga, V, In, Y, Sr and Ti; characterised in that the total atomic composition relative to Pt of X and Y at the surface of the de-alloyed catalyst as determined from X-ray photoelectron spectroscopy is between 20 and 99% lower than the total atomic composition relative to Pt of X and Y in the bulk of the de-alloyed catalyst.

20 . The de-alloyed catalyst according to claim 19 , wherein X is Ni or Co.

21 . The de-alloyed catalyst according to claim 20 , wherein X is Ni.

22 . The de-alloyed catalyst according to claim 19 , wherein Y is Zn, Al, V or Ti.

23 . The de-alloyed catalyst according to claim 19 , wherein Y is Zn.

24 . The de-alloyed catalyst according to claim 19 , wherein the total atomic percentage of X and Y in the bulk is 20-70 atomic percent.

25 . The de-alloyed catalyst according to claim 24 , wherein the total atomic percentage of X and Y in the bulk is 30 to 55 atomic percent.

26 . The de-alloyed catalyst according to claim 19 , wherein the total atomic composition relative to Pt of X and Y at the surface is between 45 and 75% lower than the total atomic composition relative to Pt of X and Y in the bulk of the de-alloyed catalyst.

27 . A de-alloyed catalyst of formula PtXY, wherein X is selected from the group consisting of Ni, Co and Cr; and Y is selected from the group consisting of Zn, Al, Sn, Be, Pb, Ga, V, In, Y, Sr and Ti; characterised in that the total atomic composition relative to Pt of X and Y at the surface of the de-alloyed catalyst as determined from X-ray photoelectron spectroscopy is between 20 and 99% less than the total atomic composition relative to Pt of X and Y in the bulk of the de-alloyed catalyst; said de-alloyed catalyst obtainable by a process comprising the steps of:
(i) preparing a catalyst alloy precursor of formula PtXY; (ii) subjecting the catalyst alloy precursor to conditions sufficient to leach a portion of X and/or Y from the catalyst alloy precursor to provide the de-alloyed catalyst.

28 . A catalyst layer comprising a de-alloyed catalyst according to claim 19 .

29 . A gas diffusion electrode comprising a gas diffusion layer and a catalyst layer according to claim 28 .

30 . A catalysed membrane comprising a proton conducting membrane and a catalyst layer according to claim 28 .

31 . A catalysed transfer substrate comprising a transfer substrate and a catalyst layer according to claim 28 .

32 . A membrane electrode assembly comprising: a de-alloyed catalyst according to claim 19 , or a catalyst layer comprising said de-alloyed catalyst, or a gas diffusion electrode comprising a gas diffusion layer and said catalyst layer, or a catalyst membrane comprising a proton conducting membrane and said catalyst layer.

33 . A process for preparing a de-alloyed catalyst of formula PtXY, wherein X is selected from the group consisting of Ni, Co and Cr; and Y is selected from the group consisting of Zn, Al, Sn, Be, Pb, Ga, V, In, Y, Sr and Ti; characterised in that the total atomic composition relative to Pt of X and Y at the surface of the de-alloyed catalyst as determined from X-ray photoelectron spectroscopy is between 20 and 99% less than the total atomic composition relative to Pt of X and Y in the bulk of the de-alloyed catalyst; said process comprising the steps of:
(i) preparing a catalyst alloy precursor of formula PtXY wherein the atomic percentage of the total of X and Y in the catalyst alloy precursor is at least 50 atomic percent; (ii) subjecting the catalyst alloy precursor to conditions sufficient to leach a portion of X and/or Y from the catalyst alloy precursor to provide the de-alloyed catalyst.

34 . The process according to claim 33 , wherein in step (ii) the catalyst alloy precursor is contacted with an acidic solution.

35 . The process according to claim 33 , wherein in step (ii) the catalyst alloy precursor is subjected to an electrochemical reaction.

36 . The process according to claim 33 , wherein in step (ii) the catalyst alloy precursor is heated in a controlled gaseous atmosphere.

37 . The de-alloyed catalyst according to claim 20 , wherein Y is Zn, Al, V or Ti.

38 . The de-alloyed catalyst according to claim 21 , wherein Y is Zn, Al, V or Ti.

Assignees

• Johnson Matthey Fuel Cells Ltd
• Gm Global Tech Operations Inc

Inventors

• Bonastre Alejandro Martinez
• O'Malley Rachel Louise
• Spikes Geoffrey Hugh
• Wagner Frederick Tadeusz

Classifications

• H01M4/926

  on carbon or graphite · CPC title

• H01M4/8807

  Gas diffusion layers · CPC title

• H01M8/1004

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

• H01M4/921 Primary

  Alloys or mixtures with metallic elements · CPC title

• H01M4/8878

  Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body · CPC title