Ru–Ni ₃ Se ₂ /NiSe@NF Self-Supported Electrode for Photoassisted Alkaline Water Splitting

Photoassisted electrocatalytic strategies have emerged as a promising approach to improve the efficiency of water electrolysis. In this study, we develop a Ru-modified Ni3Se2/NiSe self-supported bifunctional electrode (Ru–Ni3Se2/NiSe@NF), in which low-loading RuOx/Ru species are anchored onto a phase-engineered Ni3Se2/NiSe heterostructure. This design integrates the intrinsic semiconducting/photoactive character of nickel selenides with the cocatalytic role of Ru-based species acting as electron sinks, thereby enhancing both charge separation and interfacial reaction kinetics. As a result, the Ru–Ni3Se2/NiSe@NF electrode delivers efficient alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the dark, and exhibits pronounced photoresponsiveness under simulated 5-sun illumination. At a current density of 100 mA cm–2, the overpotential of HER decreases from 145 to 124 mV, while that of the OER drops from 290 to 269 mV under light, both of which are markedly lower than those of the Ru-modified nickel foam (Ru/NF) under identical conditions. Moreover, the electrode shows smaller Tafel slopes and improved operational stability in alkaline media. Overall, this work demonstrates a low-Ru-loading, self-supported nickel selenide electrode for photoassisted overall water splitting and provides mechanistic insight into the synergistic coupling between Ru-based cocatalysts and phase-engineered Ni3Se2/NiSe for hydrogen production.