Oxygen vacancies-modified S-scheme heterojunction of Bi-doped La2Ti2O7 and La-doped Bi4Ti3O12 to improve the NO gas removal avoiding NO2 product

Monoclinic phase La2Ti2O7 and orthorhombic phase Bi4Ti3O12 with layered crystal structure constructed by the perovskite slab were widely used in photocatalysis. Their electronic structures are the most crucial factor in high photocatalytic activity. Bi-doped La2Ti2O7 gradually converts to La-doped Bi4Ti3O12 with the incorporation of bismuth ions, and the two phases build an S-scheme heterojunction. More oxygen vacancies were introduced into the S-scheme heterojunction after heat treatment in a nitrogen atmosphere. The 0.1BTO/LTO-OV sample exhibits the largest NO removal efficiency of 52% and only 5.6 ppb NO2 intermediate generation. The improved NO removal efficiency was ascribed to the synergistic effect of oxygen vacancies, doping and heterojunction, providing a new insight into the photocatalytic NO removal. The photocatalytic mechanism was eventually proposed on the basis of trapping experiments.