Surface Reconstruction of Co‐based Catalysts for Enhanced Oxygen Evolution Activity in Anion Exchange Membrane Water Electrolysis

Abstract Developing high‐performance and durable electrocatalysts for the oxygen evolution reaction (OER) is of utmost importance for green hydrogen production via anion exchange membrane water electrolysis (AEMWE). Herein, it is presented that a straightforward surface reconstruction strategy for preparing a robust Co‐based OER catalyst with increased mass transfer activity while preserving the active CoOOH phase during the OER. This strategy comprises electrochemical oxidation of electrodeposited Co‐based catalysts prior to heat treatment, allowing for the meticulous control of the oxidation potential to optimize the OER activity. The optimized catalyst exhibits an overpotential of 190 mV at 10 mA cm⁻² and a Tafel slope of 32.7 mV dec⁻¹ under half‐cell conditions. In an AEMWE single‐cell system, it shows a current density of 1590 mA cm⁻² at 1.8 V and 60 °C and demonstrates a degradation rate of 0.2 mV h⁻¹ during 1000 h of operation at 500 mA cm⁻². This study not only provides a simple yet potent strategy to enhance the OER activity but also offers insights regarding the factors enhancing the OER performance.