Manipulating Electron Redistribution in Ni₂P for Enhanced Alkaline Seawater Electrolysis

Abstract Developing bifunctional electrocatalyst for seawater splitting remains a persistent challenge. Herein, an approach is proposed through density functional theory (DFT) preanalysis to manipulate electron redistribution in Ni₂P addressed by cation doping and vacancy engineering. The needle‐like Fe‐doped Ni₂P with P vacancy (Fe‐Ni₂Pv) is successfully synthesized on nickel foam, exhibiting a superior bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic activity for seawater electrolysis in alkaline condition. As a result, bifunctional Fe‐Ni₂Pv achieves the industrially required current densities of 1.0 and 3.0 A cm⁻² at low voltages of 1.68 and 1.73 V, respectively, for seawater splitting at 60 °C in 6.0 m KOH circumstances. The theoretical calculation and the experimental results collectively reveal the reasons for the enhancement of catalyst activity. Specifically, Fe doping and P vacancies can accelerate the reconstruction of OER active species and optimize the hydrogen adsorption free energy (ΔG_H*) for HER. In addition, the active sites of Fe‐Ni₂Pv are identified, where P vacancies greatly improve the electrical conductivity and Ni sites are the dominant OER active centers, meanwhile Fe atoms as active centers for the HER. The study provides a deep insight into the exploration for the enhancement of activity of nickel‐based phosphide catalysts and the identification of their real active centers.