Facial construction of defected NiO/TiO2 with Z-scheme charge transfer for enhanced photocatalytic performance

Here we report a defected NiO/TiO2 composite (NiO/TiO2-OV) fabricated by a two-step hydrothermal method with the followed one-step calcination, which induced the in situ generation of Ti3+ and oxygen vacancies, coupled with the construction of a direct Z-scheme band structure. The NiO/TiO2-OV catalyst exhibited a substantially improved performance in the photodegradation of organic pollutant and photocatalytic hydrogen evolution reaction (HER). The sensitization by narrow bandgap semiconductor of NiO enhanced the light response of catalysts. More importantly, the intrinsic defects, the Ti3+ and oxygen vacancies, acted as the mid-gap state in TiO2, and resulted in the direct Z-scheme charge transfer between the Ti3+/oxygen vacancies state and the valance band (VB) of NiO to suppress the recombination of photogenerated electrons and holes. Meanwhile, the realignment of band structure caused by constructing NiO/TiO2 heterojunction made the photogenerated carries more active in the photocatalytic reduction and oxidation reactions.