A catalyst layer including: (i) a platinum-containing electrocatalyst; (ii) an oxygen evolution reaction electrocatalyst; (iii) one or more carbonaceous materials selected from the group consisting of graphite, nanofibres, nanotubes, nanographene platelets and low surface area, heat-treated carbon blacks wherein the one or more carbonaceous materials do not support the platinum-containing electrocatalyst; and (iv) a proton-conducting polymer and its use in an electrochemical device are disclosed.