Sulfur, phosphorus and iron codoped nickel oxide as an efficient catalyst for the oxygen evolution reaction

Abstract

The oxygen evolution reaction (OER) is the efficiency limiting half-reaction in water electrolysis for hydrogen production, which necessitates the use of an efficient and cost-effective catalyst. Nonmetal and metal element codoping is an effective way to profoundly modulate the electronic structure of transition metal oxide catalysts and the interaction with oxygen (O) adsorbates, which are crucial forOER efficiency. Herein, a sulfur (S), phosphorus (P) and iron (Fe) element codoped nickel oxide (NiO), denoted as S,P-NiO(Fe), was prepared as an OER catalyst, wherein the incorporation of P and Fe played significant roles in regulating the electronic structure of the NiO motif and reducing the activation barrier of the rate-determining step (RDS) during the OER process, thus substantially enhancing the catalytic capability. Concretely, the S,P-NiO(Fe) electrode displayed an overpotential of 230 mV at an OER response of 50 mA cm⁻², a low Tafel slope of 64 mV dec⁻¹ and robust catalytic stability. Theoretical calculations showed that the incorporation of P and Fe downshifted the d-band center position, which mediated the adsorptive interaction strengths of O-intermediates and reduced the activation barrier of the RDS (from *O to *OOH), whereupon the low energy pathway led to rapid OER kinetics. This work offers a viable tactic to improve the OER catalytic capability of metal oxides through metal and nonmetal element codoping.