MEMBRANE

1 . A proton exchange membrane comprising an ion-conducting layer which comprises an ion-conducting polymer and a supported recombination catalyst, wherein the recombination catalyst is supported on graphene.

2 . The membrane according to claim 1 , wherein the supported recombination catalyst is dispersed in the ion-conducting polymer.

3 . The membrane according to claim 1 , wherein the recombination catalyst is platinum, palladium, an alloy comprising platinum, an alloy comprising palladium, or a mixture thereof.

4 . The membrane according to claim 1 , wherein the recombination catalyst is supported on graphene-based platelets.

5 . The membrane according to claim 1 , wherein the membrane comprises more than one ion-conducting layer.

6 . The membrane according to claim 5 , wherein the membrane comprises no more than six ion-conducting layers.

7 . The membrane according to claim 5 , wherein at least one ion-conducting layer does not comprise supported recombination catalyst.

8 . The membrane according to claim 1 , wherein the recombination catalyst is present in an amount in the range of and including 10 to 90 wt % of the total weight of the recombination catalyst and the graphene.

9 . The membrane according to claim 1 , wherein the membrane comprises a reinforcement material.

10 . A catalyst coated membrane comprising the membrane according to claim 1 and an electrocatalyst applied to at least one face of the membrane.

11 . The catalyst coated membrane according to claim 10 , wherein the electrocatalyst is selected from:

(i) the platinum group metals (platinum, palladium, rhodium, ruthenium, iridium and osmium);

(ii) gold;

(iii) a base metal;

or an alloy or mixture comprising one or more of these metals or their oxides.

12 . A membrane electrode assembly comprising the membrane according to claim 1 .

13 . A fuel cell comprising the membrane according to claim 1 .

14 . A proton exchange membrane electrolyser comprising the membrane according to claim 1 .