Ambient Fast Synthesis of Superaerophobic/Superhydrophilic Electrode for Superior Electrocatalytic Water Oxidation

Abstract

Developing cost‐effective and facile methods to synthesize efficient and stable electrocatalysts for large‐scale water splitting is highly desirable but remains a significant challenge. In this study, a facile ambient temperature synthesis of hierarchical nickel–iron (oxy)hydroxides nanosheets on iron foam (FF‐FN) with both superhydrophilicity and superaerophobicity is reported. Specifically, the as‐fabricated FF‐FN electrode demonstrates extraordinary oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at 10 mA cm−2 and a small Tafel slope of 34 mV dec−1 in alkaline media. Further theoretical investigation indicates that the involved lattice oxygen in nickel–iron‐based‐oxyhydroxide during electrochemical self‐reconstruction can significantly reduce the OER reaction overpotential via the dominated lattice oxygen mechanism. The rechargeable Zn–air battery assembled by directly using the as‐prepared FF‐FN as cathode displays remarkable cycling performance. It is believed that this work affords an economical approach to steer commercial Fe foam into robust electrocatalysts for sustainable energy conversion and storage systems.