NiFe2O4–Ni3S2 nanorod array/Ni foam composite catalyst indirectly controlled by Fe3+ immersion for an efficient oxygen evolution reaction

A NiFe alloy was designed on nickel foam (NF) as a precursor using cathodic electrodeposition. NiFe2O4–Ni3S2 nanorods (NRs) composite catalysts were prepared by Fe3+ impregnation and further hydrothermal sulfuration methods. NiFe2O4–Ni3S2 nanosheets (NSs) were also prepared by direct hydrothermal sulfuration of the NiFe alloy for comparison. Compared to the dense NS structure of the NiFe2O4–Ni3S2 NSs/NF, the NiFe2O4–Ni3S2 NRs/NF showed better oxygen evolution performance due to its unique weed-like NR array structure composed of additional oxygen evolution reaction (OER) active sites, with a strong electron interaction for Ni and Fe and the active sulfide synergistic effect with oxides. Therefore, Driving a current density of 10 mA cm−2 only requires an overpotential of 189 mV and the catalyst could provide 100 mA cm−2 continuously and be constant for more than 80 h in 1.0 M KOH. This experiment indicated that Fe3+ immersion had an indirect regulating effect on the morphological growth of the catalyst, which provided a novel concept for designing better OER catalysts.