Electron redistribution induced by p–d orbital hybridization in Co2P/FeP nanosheets boosts water electrooxidation

Abstract

Water electrooxidation in proton exchange membrane (PEM) water electrolyzers has been considered to be a four-electron pathway mechanism, which leads to inherent sluggish kinetics that severely limits the scalable production of high-purity H₂. Herein, cobalt phosphide/iron phosphide (Co₂P/FeP) nanosheets with electron redistribution through aerogel-assisted and gas-phase phosphorization strategies have been reported. Benefiting from the unique nanosheet structure and electron redistribution induced by p–d hybridization interaction, the as-obtained Co₂P/FeP nanosheets display outstanding alkaline oxygen evolution reaction (OER) performance. Co–P and Fe–P charge bridges trigger p–d orbital hybridization between the transition metal and P elements, which downshifts the d-band center of Co₂P/FeP nanosheets and accelerates the formation of *OOH with a lower energy barrier that can expedite the water electrooxidation process with an overpotential of 257 mV to reach the 10 mA cm⁻² current density and a Tafel slope of 39.6 mV dec⁻¹. This work provides a deep insight into understanding the remarkable OER properties of transition metal phosphates by electron redistribution.