Highly durable porous NiO-derived electrodes with superior bifunctional activity for scalable alkaline water electrolysis

Abstract

Alkaline water electrolysis (AWE) is a leading “green hydrogen” production technology. Industrial electrodes use alkaline leaching to remove Al from NiAl alloy, creating pores and increasing specific surface area (SSA) but still suffer from poor electrode performance. This study presents a method for fabricating an efficient bifunctional electrode. The process involves creating a porous Ni layer with high SSA on nickel mesh (NM) by reducing NiO, which facilitates the formation of Ni(OH)₂ nanosheets. The resulting Ni/Ni(OH)₂@NM electrode features a hydrophilic, gas-repellent and highly electrochemically active surface. It achieves low overpotentials for hydrogen and oxygen evolution reactions (164 mV and 337 mV at 100 mA/cm², respectively). The electrolyzer using Ni/Ni(OH)₂@NM electrodes only requires 1.695 V to achieve 300 mA/cm² at 80 °C after a 2000 h durability test. The electrode also demonstrates excellent stability under frequent start-stop cycles, making it well-suited for integration with intermittent renewable energy sources.