Manipulating Electron Redistribution in Ni2P for Enhanced Alkaline Seawater Electrolysis

Abstract

AbstractDeveloping 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 (ΔGH*) 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.