NiFeOOH deposition on various 3D electrode geometries to influence bubble dynamics under technical relevant alkaline water electrolysis conditions

Abstract

Improving alkaline water electrolysis efficiency is limited by high overpotential at the oxygen-evolving anode, especially at high current densities. This overpotential depends on catalytic activity and multiphase dynamics, which optimised 3D electrode structures, like metal meshes, gauzes, and expanded sheets, can enhance. We present a scalable, three-step galvanic deposition for fabricating porous NiFeOOH catalysts on 3D nickel substrates. Electrochemical performance is evaluated in near-industrial (1 M KOH, 35 °C) and industrially relevant (30 wt-% KOH, 80 °C) conditions in a three-electrode setup, achieving high stability and activity at current densities up to 1.2 A cm⁻². Tuning the iron content during deposition yields optimal activity with increased iron content under industrial conditions. The catalyst on plain-woven Ni mesh maintains 1.43 V vs. RHE at 500 mA cm⁻² for 100 h. Successful transfer of the deposition method to expanded Ni sheet achieved 1.44 V vs. RHE at 1 A cm⁻², surpassing an industrial benchmark (1.50 V vs. RHE).