Surface reconstruction of CoAl hydroxide electrodes foraccelerated oxygen evolution reaction

Abstract

Water electrolysis powered by renewable energy is recognized as a sustainable approach for green hydrogenproduc-tion. Rational design of efficient and low-cost electrocatalysts especially for the sluggish oxygen evolution reaction(OER) remains a significant challenge. Here, we report a two-step surface reconstruction strategy, alkaline etching andanodic activation on CoAl hydroxide electrodes which remarkably enhance the OER performance. A low overpotential of269 mV at 10 mA cm−2 is achieved in 1 M KOH electrolyte, along with a notably reduced Tafel slope of 37 mV dec−1, a 16-fold enhanced catalyst intrinsic activity at an overpotential of 300 mV, and excellent stability without noticeabledegrad-ation over 50 hours operation. The dynamic surface reconstruction of CoAl hydroxide catalyst is evidenced by physicalcharacterization in the process of alkaline etching and anodic activation. The defective structure and the modulatedelectronic distribution on the catalyst surface are demonstrated to facilitate electron transfer and OER kinetics. Our workpresents a feasible surface reconstruction approach for designing high-efficiency catalytic electrodes in alkaline waterelectrolysis.