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.