Constructing a homojunction of Fe–Ni3S2 as a highly efficient electrocatalyst for the oxygen evolution reaction

Abstract

Nickel sulfide (Ni₃S₂) is a promising candidate as an electrocatalyst for the oxygen evolution reaction (OER). However, improving the intrinsic activity and stability of Ni₃S₂ material remains a challenge. Herein, we regulated multi-crystal planes of Ni₃S₂ and constructed homojunction structures to improve its OER performance. This Ni₃S₂ material was successfully fabricated on nickel foam (NF) using a solvothermal reaction and modified by incorporation of an Fe atom via a gas-phase cation-exchange strategy. The crystal planes and electron structures could be efficiently regulated, and homojunctions were also formed between different crystal planes, which promoted electron transfer across the crystal interfaces. Additionally, modulation of the electron structures changed the electron cloud density by the incorporation of the Fe atom, leading to the transfer of outer electrons from S to Ni. As a result, the optimized d-band center improved the adsorption and desorption capacity of the oxygen-containing intermediates. The electrocatalytic tests demonstrated that the as-prepared Fe–Ni₃S₂ material exhibited excellent OER performance in alkaline solution, with overpotentials of 230 and 287 mV at current densities of 10 and 100 mA cm⁻², respectively, outperforming RuO₂ and other reported materials. The Fe–Ni₃S₂ material displayed a comparable stability of more than 100 h. This research provides a feasible strategy for preparing crystal plane- and electron structure-controlled Ni₃S₂ materials for the OER and other electrocatalytic reactions.