Uniform Ordered Mesoporous NiCoFe Alloy Nanospheres for Superior Alkaline Oxygen Evolution Reaction

Improving the kinetics of the oxygen evolution reaction (OER) is critical for the widespread adoption and application of water electrolysis technology, which has become a key strategy in addressing energy and environmental challenges. Ni-based transition metal alloy catalysts offer several advantages, including high catalytic capability, tunable composition, low cost, excellent corrosion resistance, and environmental friendliness, making them highly attractive for catalyzing OER in alkaline electrolysis. In this study, we synthesized a series of highly ordered mesoporous NiCoFe alloy nanospheres (OM-NiCoFe) with varying elemental compositions and uniform sphere diameters using a facile wet chemical reduction method and evaluated their OER performance in alkaline media. Owing to their unique ordered mesoporous structure, which promotes mass transport, increases specific surface area, and enhances the accessibility of active sites, combined with the synergistic catalytic effect among different metal elements, the OM-NiCoFe catalysts achieved high current densities (>500 mA cm^-2) at potentials below 1.7 V vs RHE during the OER process. Notably, the OM-Ni₄₇Co₃₅Fe₁₈ sample, with the optimal elemental composition, exhibited a low overpotential of 193 mV at 10 mA cm^-2, a small Tafel slope of 32.2 mV dec^-1, and excellent stability (with negligible potential change at a current density of 200 mA cm^-2 for 120 h), outperforming other reference samples and most Ni-based OER electrocatalysts. This work presents an effective strategy for preparing ordered mesoporous spherical metallic materials that not only deliver competitive OER performance but also offer a versatile platform for applications in energy conversion and storage, adsorption, and magnetism.