Nanoarchitectonics of Fe-Doped Ni₃S₂ Arrays on Ni Foam from MOF Precursors for Promoted Oxygen Evolution Reaction Activity

Oxygen evolution reaction (OER) is a critical half-reaction in electrochemical overall water splitting and metal–air battery fields; however, the exploitation of the high activity of non-noble metal electrocatalysts to promote the intrinsic slow kinetics of OER is a vital and urgent research topic. Herein, Fe-doped Ni₃S₂ arrays were derived from MOF precursors and directly grown on nickel foam via the traditional solvothermal way. The arrays integrated into nickel foam can be used as self-supported electrodes directly without any adhesive. Due to the synergistic effect of Fe and Ni elements in the Ni₃S₂ structure, the optimized Fe_2.3%-Ni₃S₂/NF electrode delivers excellent OER activity in an alkaline medium. The optimized electrode only requires a small overpotential of 233 mV to reach the current density of 10 mA cm⁻², and the catalytic activity of the electrode can surpass several related electrodes reported in the literature. In addition, the long-term stability of the Fe_2.3%-Ni₃S₂/NF electrode showed no significant attenuation after 12 h of testing at a current density of 50 mA cm⁻². The introduction of Fe ions could modulate the electrical conductivity and morphology of the Ni₃S₂ structure and thus provide a high electrochemically active area, fast reaction sites, and charge transfer rate for OER activity.