Construction of Self-healing Active Centers over Amorphous Ni2Fe(OH)x Nanosheets for Enhanced Oxygen Evolution Performance

Developing efficient nickel–iron-based electrocatalysts for the oxygen evolution reaction (OER) still remains a challenge for long-term application in water electrolysis. Herein, amorphous Ni2Fe hydroxide nanosheets with self-healing active centers supported on stainless steel mesh (a-Ni2Fe(OH)x/SSM) are fabricated using a simple electrochemical deposition strategy. In situ Raman evidence shows that the amorphous structure of a-Ni2Fe(OH)x/SSM exhibits strong self-healing ability, efficiently promoting the rapid interconversion between the γ-NiOOH intermediate and Ni-based hydroxides during electrocatalysis. As a result, the as-obtained a-Ni2Fe(OH)x/SSM exhibits a low overpotential of 247 mV at 100 mA cm–2 and robust electrochemical stability for 200 h. Moreover, an anion-exchange membrane electrolyzer for water splitting is assembled utilizing a-Ni2Fe(OH)x/SSM as the anode, and current densities of 500 and 1000 mA cm–2 are achieved at 1.62 and 1.72 V, respectively, with stable performance at 500 mA cm–2 over 30 h. This work provides a facile approach for designing amorphous catalysts for various useful reactions.