Multivalent cation-modified NixSy for highly efficient and stable oxygen evolution electrocatalysis

Abstract

Developing highly efficient and stable non-precious metal electrocatalysts for the oxygen evolution reaction (OER) is an ongoing challenge due to the sluggish kinetics of the OER. In this study, the (Ni,Fe,V)₃S₄–NiS nanoheterostructure rich in Ni³⁺ was obtained by sulfidizing the NiFeV layered double hydroxide hydrogen precursor. The introduction of Fe and V effectively modified the electronic structure of Ni_xS_y and increased the content of Ni³⁺, which was conducive to enhancing the chemisorption of OH⁻ and promoting the transfer of electrons to the surface during the OER process. At the same time, the self-supporting porous structure, the unique metallic characteristics of Ni_xS_y (continuous Ni–Ni bonds) and excellent electrical conductivity can facilitate electrolyte diffusion and bubble release. The designed (Ni,Fe,V)₃S₄–NiS/NF electrode shows excellent electrocatalytic OER performance with an overpotential of 236 mV at a current density of 10 mA cm⁻², ultra-low Tafel slope (53.7 mV dec⁻¹) and excellent long-term stability. Therefore, this work offers a simple strategy to design an efficient Ni based OER electrocatalyst enriched with Ni³⁺ sites by co-doping high-valence ions.