Surface Reconstruction of NiFeSe Electrocatalytic Nanosheets Promoted by Chromium Doping as a Key for the Generation of Active Species in the Oxygen Evolution Reaction

Transition-metal selenides (TMSes) have garnered significant research attention in recent years due to their low cost, intrinsic metallic properties, and high theoretical catalytic activity. During the oxygen evolution reaction (OER) process, the surface of transition-metal selenides undergoes reconstruction and transforms into oxyhydroxides, which serve as the true active species. Herein, a strategy is proposed to optimize oxygen evolution reaction (OER) catalytic activity through the leaching of chromium, which enlarged the electrochemical surface area by exposing more active sites and generated more active phases. Electrochemical testing results reveal that the Cr-NiFeSe nanosheets catalyst exhibits a low overpotential of 209 mV at a current density of 10 mA cm–2 and a high durability of 200 h at 100 mA cm–2 in alkaline electrolytes. Density functional theory (DFT) calculations confirm that the introduction of Cr enhances the orbital hybridization and redistribution of electrons around Cr atoms. In addition, Cr doping reduces the OER reaction barrier of the potential-determining step, resulting in an improvement of the catalytic efficiency. This work provides insight into the design of OER electrocatalysts with a deep electrochemical reconstruction process through the regulation of ion leaching.