CATALYST LAYER
A catalyst layer includes (i) an electrocatalyst, and (ii) a water electrolysis catalyst, iridium or iridium oxide and one or more metals M or an oxide thereof, wherein M is selected from transition metals and/or Sn, with the exception of ruthenium. Such a catalyst layer has utility in fuel cells that experience high electrochemical potentials.
1 . A catalyst layer comprising:
(i) an electrocatalyst, and
(ii) a water electrolysis catalyst, wherein the water electrolysis catalyst comprises iridium or iridium oxide and one or more metals M or an oxide thereof, wherein M is selected from the group consisting of transition metals and Sn, with the exception of ruthenium.
2 . A catalyst layer according to claim 1 , wherein M is selected from the group consisting of Group IVB, VB and VIB metals and Sn.
3 . A catalyst layer according to claim 2 , wherein M is selected from the group consisting of Ti, Zr, Hf, Nb, Ta and Sn.
4 . A catalyst layer according to claim 1 , wherein the water electrolysis catalyst is unsupported.
5 . A catalyst layer according to claim 1 , wherein the electrocatalyst comprises a metal which is selected from the group consisting of
(i) platinum group metals,
(ii) gold or silver,
(iii) a base metal,
and an oxide thereof.
6 . A catalyst layer according to claim 1 , wherein the electrocatalyst is supported on an inert support.
7 . A catalyst layer according to claim 6 , wherein the inert support is non-carbonaceous.
8 . A catalyst layer according to claim 1 , wherein the electrocatalyst is unsupported.
9 . A catalyst layer according to claim 8 , wherein the electrocatalyst is unsupported platinum.
10 . An electrode comprising a gas diffusion layer and a catalyst layer as claimed in claim 1 .
11 . A catalysed membrane comprising a solid polymeric membrane and a catalyst layer as claimed in claim 1 .
12 . A catalysed transfer substrate comprising a transfer substrate and a catalyst layer as claimed in claim 1 .
13 . A membrane electrode assembly comprising a catalyst layer as claimed in claim 1 .
14 . A fuel cell comprising a catalyst layer as claimed in claim 1 .
15 . A membrane electrode assembly comprising an electrode as claimed in claim 10 .
16 . A membrane electrode assembly comprising a catalysed membrane as claimed in claim 11 .
17 . A fuel cell comprising an electrode as claimed in claim 10 .
18 . A fuel cell comprising a catalysed membrane as claimed in claim 11 .