Nickel hydroxide enhanced nickel selenides for oxygen evolution reaction

Transition to sustainable energy systems relies on the development of efficient and cost-effective hydrogen production technologies. A major challenge in this field is designing high-performance electrocatalysts based on earth-abundant, low-cost materials. In this work, three nickel selenide phases, NiSe₂, NiSe, and Ni₃Se₂, along with their corresponding Ni(OH)₂-modified heterostructures, were synthesized on nickel foam and systematically evaluated as oxygen evolution reaction (OER) electrocatalysts in alkaline media. X-ray diffraction and scanning electron microscopy analyses revealed that the incorporation of Ni(OH)₂ profoundly influenced nucleation pathways and pro­moted more homogeneous active-phase distribution across the three-dimensional substrate. Electrochemical characterization demonstrated that all Ni(OH)₂-modified electrodes exhibited enhanced catalytic performance compared to their unmodified counterparts. Among them, NiSe-OH supported on nickel foam, referred to as NiSe-OH/NF, achieved the lowest overpotential of 177 mV at 10 mA cm⁻² and displayed favourable reaction kinetics, as reflected by its Tafel slope. The improved activity was attributed to synergistic interactions between Ni and Se, the activation of the Ni(OH)₂/NiOOH redox couple, and optimized charge-transfer pathways facilitated by the heterostructured interface. Long-term stability tests confirmed that the hybrid catalysts maintained over 86 % of their maximum current density after extended operation. These results establish Ni-Se/Ni(OH)₂ heterostructures as promising, earth-abundant materials for efficient alkaline OER and offer new insights into interface engineering for next-generation electrocatalyst design.