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

•Ni catalyst was electrodeposited on carbon paper.•The Ni loading and microstructure were controlled by deposition potential and time.•A membrane electrode assembly was prepared for alkaline water electrolyzer.•The Ni loading was extremely low at 8.5 μg/cm2.•The developed MEA exhibited current density of 150 mA cm−2 at cell voltage of 1.9 V.

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 μgNi 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.

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