Catalyst

1. A process for preparing a catalyst material, said catalyst material comprising a support material, a first metal and one or more second metals, wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group of transition metals and tin provided the second metal(s) is different to the first metal, said process comprising the steps:

(i) providing a catalyst material precursor comprising the first metal supported on the support material;

(ii) depositing a silicon oxide precursor and one or more second metal precursors on the catalyst material precursor;

(iii) carrying out a first heat treatment step to convert the silicon oxide precursor to silicon oxide;

(iv) carrying out a second heat treatment step to alloy the first metal and the second metal(s); and

(v) removing at least some of the silicon oxide to give the catalyst material.

2. The process according to claim 1 , wherein in step (ii) the silicon oxide precursor is deposited prior to the second metal precursor(s).

3. The process according to claim 1 , wherein in step (ii) the second metal precursor(s) is deposited prior to the silicon oxide precursor.

4. The process according to claim 1 , wherein the catalyst material comprises two or more second metals and wherein in step (ii) each second metal precursor is independently deposited either before or after the silicon oxide precursor.

5. The process according to claim 1 , further comprising step (vi):

(vi) removal of some or all unalloyed second metal(s) and/or removal of a portion of alloyed second metal(s) from the surface of the catalyst material.

6. The process according to claim 1 , wherein the first heat treatment step is carried out at a temperature in the range of 250° C. to 500° C.

7. The process according to claim 1 , wherein the second heat treatment step is carried out at a temperature in the range of 350° C. to 1000° C.

8. The process according to claim 1 , wherein the first and second heat treatment steps are carried out as a single sequential process, the second heat treatment step being a continuation of the first heat treatment step.

9. The process according to claim 1 , wherein the first metal is platinum.

10. The process according to claim 1 , wherein the second metal(s) is one or more metals selected from the group consisting of precious metals other than platinum and base metals.

11. The process according to claim 10 , wherein the second metal(s) is selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, gold, silver, nickel, cobalt, chromium, copper, iron, zinc, niobium, tantalum, vanadium, tin or titanium.

12. The process according to claim 11 , wherein second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron zinc, osmium, ruthenium, niobium, tantalum, vanadium, tin, titanium and rhodium.

13. The process according to claim 12 , wherein the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron or zinc.

14. The process according to claim 12 , wherein the second metal(s) is selected from the group consisting of osmium, ruthenium, niobium, tantalum, vanadium, iridium, tin, titanium or rhodium.

15. The process according to claim 1 , wherein up to 5 wt % of silicon with respect to the weight of the catalyst material remains after step (v).

16. The catalyst material obtained by the process according to claim 1 .

17. A cathode catalyst material comprising a support material, a first metal and one or more second metals, wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron or zinc, provided the first metal and second metal(s) are not the same, characterised in that the atomic ratio of first metal to total second metal(s) is ≥1, and the CO metal area of the cathode catalyst material, as measured by gas phase carbon monoxide (CO) chemisorption, is at least 56 m 2 /g of the platinum group metal components.

18. An anode catalyst material comprising a support material, a first metal and one or more second metal(s), wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group consisting of osmium ruthenium, niobium tantalum, vanadium iridium tin titanium or rhodium, provided that the first metal and the second metal(s) are not the same, characterised in that the atomic ratio of first metal to total second metal(s) is ≥0.5 and the CO metal area of the anode catalyst material, as measured by gas phase carbon monoxide (CO) chemisorption, is at least 18 m 2 /g of platinum group metal components.

19. A catalyst layer comprising a cathode catalyst material according to claim 17 .

20. A cathode catalyst material according to claim 17 , wherein the first metal is platinum, ruthenium, rhodium, osmium or iridium.

21. A cathode catalyst material according to claim 20 , wherein the first metal is platinum.

22. A cathode catalyst material according to claim 17 , wherein the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, iridium, copper, iron, or zinc.

23. A cathode catalyst material according to claim 22 , wherein the second metal is nickel.

24. An anode catalyst material according to claim 18 , wherein the first metal is platinum, ruthenium, rhodium, osmium, or iridium.

25. An anode catalyst material according to claim 24 , wherein the first metal is platinum.

26. An anode catalyst material according to claim 18 , wherein the second metal is rhodium.

27. A catalyst layer comprising an anode catalyst material according to claim 18 .