Iron-facilitated Surface Reconstruction to In-situ Generate Nickel − iron Oxyhydroxide on Self-supported FeNi Alloy Fiber Paper for Efficient Oxygen Evolution Reaction

Abstract High-performance and low-cost electrocatalysts for oxygen evolution reaction (OER) are urgently desired to improve the overall efficiency of electrochemical water splitting. Here, a porous and self-supported FeNi-alloy fiber paper is successfully fabricated to achieve excellent OER performance with an ultralow overpotential, as well as remarkable stability. It is demonstrated that Fe substitution into metallic nickel can enable the inactive metallic nickel to endow highly electrocatalytic activity. Therefore, Fe substitution plays a key role for the outstanding performance. Specifically, the leaching of partial Fe atoms on surface of alloy facilitates surface reconstruction to generate active FeNi-oxyhydroxides under OER conditions. Meanwhile, Fe atoms can induce the lengthening of Ni-O bonds within oxyhydroxides for promoting the decomposition of *OOH intermediate species into O2. This work provides new insights into the underlying mechanisms of Fe substitution into metal nickel for improving OER activity, which can accelerate the exploitation of low-cost, efficient and durable electrocatalysts.