Magnesium-promoted rapid self-reconstruction of NiFe-based electrocatalysts toward efficient oxygen evolution.

The acceleration of active sites formation through surface reconstruction is widely acknowledged as the crucial factor in developing high-performance oxygen evolution reaction (OER) catalysts for water splitting. Herein, a simple one-step corrosion method and magnesium (Mg)-promoted strategy are reported to develop the NiFe-based catalyst with enhanced OER performance. The Mg is introduced in NiFe materials to preparate a "pre-catalyst" Mg-Ni/FeO. In-situ Raman shows that Mg doping would accelerate the self-reconstruction of Ni/FeO to form active NiOOH species during OER. In-situ infrared indicates that Mg doping benefits the formation of *OOH intermediate. Theoretical analysis further confirms that Mg doping can optimize the adsorption of oxygen intermediates, accelerating the OER kinetics. Accordingly, the Mg-Ni/FeO catalyst exhibits excellent OER performance with overpotential of 168 mV at 10 mA cm. The anion exchange membrane water electrolyzer achieved 200 mA cm at voltage of 1.53 V, showing excellent stability over 500 h as well. This work demonstrates the potential of Mg-promoted strategy in regulating the activity of transition metal-based OER electrocatalysts.