Facile and scalable synthesis of Ni3S2/Fe3O4 nanoblocks as an efficient and stable electrocatalyst for oxygen evolution reaction

This study employed a one-step hydrothermal process to synthesize Ni3S2/Fe3O4 nanoblocks in situ on nickel foam (NF). The resulting Ni3S2/Fe3O4/NF catalyst demonstrates exceptional electrocatalytic activity for the oxygen evolution reaction (OER) and robust long-term stability. It achieves a low overpotential of only 220 mV for a current density of 10 mA cm−2 with a Tafel slope of 54.1 mV dec−1 and remains stable in 1.0 M KOH for 66 h. The binder-free self-supported three-dimensional nanoblocks enhance the reaction region and long-term stability. Electronic interactions between Fe3O4 and Ni3S2, coupled with heterogeneous interfaces, optimize the electronic structure, fostering the formation of highly reactive species. Density-functional theory (DFT) calculations confirm that Ni3S2/Fe3O4, with a heterogeneous interfacial structure, modulates the chemisorption of reaction intermediates on the catalyst surface, optimizing the Gibbs free energies (ΔG) of oxygen-containing intermediates. The synergistic effect between the two active materials within the heterogeneous structure enhances OER catalytic performance. This finding offers a valuable approach to designing efficient and stable OER electrocatalysts.