KSCN-activation of hydrogenated NiO/TiO₂ for enhanced photocatalytic hydrogen evolution

It was investigated the efficiency of hydrogen production from NiO-loaded TiO₂ treated by methanol hydrogenation and functionalized by SCN ligand (SCN-M:(NiO/TiO₂)). The effects of a p-n junction created between NiO and TiO₂ were demonstrated to enhance significantly the overall photocatalytic performance. The optical and microstructural properties of SCN-M:(NiO/TiO₂) were studied with ultraviolet–visible spectra (UV–Vis), photoluminescence (PL), Raman spectra, X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The atomic and electronic configurations of SCN-M:(NiO/TiO₂) were investigated with analysis of the X-ray absorption near-edge structure (XAS) in situ under irradiation with Xe lamp incorporating a filter (AM 1.5G). An effective quantum yield of 1.34% for hydrogen production was attained with SCN-M:(NiO/TiO₂). Quantum-chemical calculations revealed a synergistic decrease of the band gap upon loading Ni, Ni-linked O₂ and anionic SCN-ligand binding. The optimal energy bandgap was decreased to 2.70 eV for (SCN/O₂)-3Ni@TiO₂, which reasonably supported the enhancement of H₂ evolution.