Carbonaceous Hydrogen‐Evolution Catalyst Containing Cobalt Surrounded by a Tuned Local Structure

Abstract The low activity and durability of noble‐metal‐free catalysts in acidic media are major problems that hinder their practical use. This study reports significantly enhanced activity of a cobalt‐containing carbonaceous catalyst used for the hydrogen‐evolution reaction in a water electrolyzer by using a proton‐exchange membrane (PEM), which is an efficient energy‐conversion device that is suitable for intermittent renewable energy sources. On the basis of X‐ray absorption near‐edge structure, the enhancement in activity was attributed to a change in the local structure surrounding the Co atom. The PEM water electrolyzer formed by using the catalyst with an optimized structure and Co surface concentration showed an enthalpy efficiency of 80 % at 1 A cm −2 .