Superior performance of anion exchange membrane water electrolyzer: Ensemble of producing oxygen vacancies and controlling mass transfer resistance

A chemically etched CuCo-oxide (CE-CCO) electrode prepared by electrodeposition was used for oxygen evolution reaction electrocatalyst. Surface chemical etching of CuCo-oxide (CCO) introduced oxygen vacancies and thus increased electrical conductivity to promote oxygen generation. During practical applicability testing, when CE-CCO was used as the anode of an anion-exchange membrane water electrolyzer, enhanced oxygen evolution performance was observed (current density = 1390 mA/cm2 at 1.8 Vcell), which, among other reactions, was ascribed to the easy removal of O2 from the aerophobic electrode surface. In addition to featuring low mass transfer resistance even at high current density with substantial gas generation, the CE-CCO electrode featured remarkable durability, exhibiting stable performance over 3600 h under the conditions of continuous O2 evolution. Thus, this work shows that the performance of electrodeposited oxide catalysts can be enhanced by introducing oxygen vacancies, while the energy conversion efficiency of the corresponding water electrolysis systems can be increased by lowering mass transfer resistance via efficient gas removal and reactant supply.