The Z-scheme inorganic intergrowth bulk heterojunction to achieve the photostimulated oxygen vacancy regeneration for photocatalytic CO2 reduction

An inorganic intergrowth bulk heterojunction (IIBH) NiO(Ti)/Ti3O5(Ni,Ga) has been constructed by two-stage topological pyrolysis method based on the structure memory effect of NiTiGa-LDHs. The Z-scheme mechanism for regenerating oxygen vacancy was investigated by ISI-XPS. It can be speculated that the photogenerated electron transfer process between the Ni2+/Ni3+ and Ti4+/Ti3+ redox pairs across the interface of the IIBH and resulted in the excess oxygen vacancies, which was active in the photocatalytic CO2 reduction. This IIBH exhibited the well-established photocatalytic efficiency for CO2 reduction with CO yields up to 2,560.1 μmol/g·h, which were 6.97 times higher than those of the NiTiGa-LDHs and the 4.95 times higher than that of NiTiGa-MMO, respectively. Under the 60 hr cyclic photocatalytic CO2 reduction experiments, the stability could still be maintained at 96.7%. This work provided an innovative approach for designing defective catalysts by the electrons transfer from the redox pairs thus inducing the regeneration of oxygen vacancies.