Interface-driven electronic modulation for photo-assisted electrochemical water splitting

Photo-assisted electrocatalysis offers a promising pathway for efficient solar-powered hydrogen production. However, controlling the separation of photogenerated carriers under electro-driven conditions through structural design remains a significant challenge. This work proposes a Group VIA anion modulation strategy for synthesizing a series of Ni(OH)₂-based heterojunction nanoarrays (Ni(OH)₂/NiO, Ni(OH)₂/NiS₂, and Ni(OH)₂/NiSe₂). The optimized Ni(OH)₂/NiS₂ heterostructure exhibits excellent photo-assisted electrocatalytic activity, reducing the overpotentials of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to 156 mV and 260 mV at 10 mA cm⁻², respectively, while achieving a high photocurrent density of 4.9 mA cm⁻². Furthermore, quantitative decoupling analysis reveals a synergistic “photo-electro-thermal” mechanism, indicating that the heterojunction simultaneously amplifies photothermal heating and enhances the non-thermal transient photoelectric effect. Combined in situ spectroscopic characterization and DFT calculations reveal that the introduction of sulfur/selenium not only broadens the light absorption range but also constructs an interfacial Ohmic contact through work function modulation, promoting charge separation and optimizing surface reconstruction thermodynamics, thereby effectively reducing the reaction barrier. This work provides a rational design strategy for high-performance water-splitting electrocatalysts and elucidates the electronic modulation of heterointerfaces in photo-assisted electrocatalysis.