Fabrication of a high-adsorption N–TiO2/Bi2MoO6 composite photocatalyst with a hierarchical heterostructure for boosted weak-visible-light photocatalytic degradation of tetracycline

Abstract

A novel Bi₂MoO₆/N–TiO₂ hierarchical heterostructure photocatalyst was successfully fabricated through the in situ growth of Bi₂MoO₆ nanosheets on rough N–TiO₂ nanorods with a bark-like surface, and the structure–property relationship of this composite material was researched. The results show that the unique bark-like morphology of N–TiO₂ leads to superior adsorption ability, and also provides effective growth sites for Bi₂MoO₆ nanosheets. The growth of Bi₂MoO₆ nanosheets leads to the formation of a hierarchical structure, therefore increasing the adsorption ability. The heterostructure between Bi₂MoO₆ and N–TiO₂ promotes the highly efficient separation and transfer of photogenerated carriers. These features make the Bi₂MoO₆/N–TiO₂ composite photocatalyst exhibit outstanding photocatalytic activity, and the optimal photocatalytic degradation rate for tetracycline hydrochloride (20 mg L⁻¹) is up to 93.76% in 90 min under weak-visible-light irradiation (5 W, LED, λ > 400 nm). After five cycling runs, the composite photocatalyst still maintains high photocatalytic activity. Holes and superoxide radicals are confirmed to be the main reactive species in the photocatalytic reaction over the Bi₂MoO₆/N–TiO₂ composite photocatalyst.