Electronic Structure Regulation and Surface Reconstruction of Iron Diselenide for Enhanced Oxygen Evolution Activity

Regulating the electronic structure of active sites and monitoring the evolution of the active component is essential to improve the intrinsic activity of catalysts for electrochemical reactions. Herein, a highly efficient pre-electrocatalyst of iron diselenide with rich Se vacancies achieved by phosphorus doping (denoted as P-FeSe₂ ) for oxygen evolution reaction (OER) is reported. Systematically experimental and theoretical results show that the formed Se vacancies with phosphorus doping can synergistically modulate the electronic structure of FeSe₂ and facilitate OER kinetics with the resulting enhanced electrical conductivity and electrochemical surface area. Importantly, the in situ formed FeOOH species on the surface of the P-FeSe₂ nanorods (denoted as P-FeOOH(Se)) during the OER process acts as an active component to efficiently catalyze OER and exhibits a low overpotential of 217 mV to reach 10 mA cm^-2 with good durability. Promisingly, an alkaline electrolyzer assembled with P-FeOOH(Se) and Pt/C electrodes requires an ultra-low cell voltage of 1.50 V at 10 mA cm^-2 for overall water splitting, which is superior to the RuO₂ || Pt/C counterpart and most of the state-of-the-art electrolyzers, demonstrating the high potential of the fabricated electrocatalyst by P doping strategy to explore more highly efficient selenide-based catalysts for various reactions.