Development of a membrane electrode assembly for alkaline water electrolysis by direct electrodeposition of nickel on carbon papers

Abstract

A membrane electrode assembly (MEA) for use in an alkaline water electrolyzer is fabricated by sandwiching an anion exchange membrane (AEM) between two electrodes prepared by the electrodeposition of Ni (used as a catalyst) on carbon papers (CPs) acting as gas diffusion layers. The conditions for Ni electrodepositon are determined on the basis of the results of half-cell tests for hydrogen and oxygen evolution reactions. An MEA fabricated by the direct electrodeposition of an extremely low Ni amount of 8.5 mu g(Ni) cm(-2) exhibits a high cell performance of 150 mA cm(-2) at 1.9 V when a 1.0 M KOH solution is supplied to the cathode. Electrodeposited Ni is uniformly distributed on the surface of CP fibers, thereby providing a large electrochemical surface area for gas evolution reactions and thus maintaining high catalyst utilization. It is suggested that control of bubble generation and AEMs with higher ionic conductivity would further increase MEA performance.