Iron and vanadium in perovskite hydroxide enabling the relay catalysis for oxygen evolution

Abstract The sluggish kinetics of the oxygen evolution reaction (OER) process impedes the exploration of green hydrogen via water splitting. Herein, we design and synthesize vanadium‐doped CoSn(OH) 6 perovskite hydroxide catalysts by Fe 3+ etching during the hydrothermal and chemical deposition process. The as‐prepared CoVSn(OH) 6 @CoVSnFe(OH) x −4 catalyst exhibits a low overpotential of 225 mV at 10 mA·cm −2 with a Tafel slope of 30.47 mV·dec −1 . An overall water splitting electrolyzer (CoVSn(OH) 6 @CoVSnFe(OH) x −4 || Pt/C) is constructed, delivering a voltage of 1.48 V at a current density of 10 mA·cm −2 with excellent durability. The dynamic phase evolution during the OER process is revealed by in situ Raman and XPS measurement, which represents that the introduced V and Fe ions facilitate the formation of active CoOOH as well as modify the electronic structure of the catalyst. Density functional theory (DFT) calculations further evidence that V and Fe introduction optimize the adsorption energies of oxygen intermediates *OH and *O, respectively, thereby enabling a synergistic optimization of the multi‐step OER process and advancing electrocatalytic performance.