Two-step alcohothermal synthesis and characterization of enhanced visiblelight-active WO3-coated TiO2 heterostructure

A new kind of WO3-coated TiO2 heterostructure with higher photocatalytic activity was prepared via a novel two-step alcohothermal synthesis process. The effects of the WO3 addition on the TiO2/WO3 products were systematically studied, including analysis of the phases, observation of the morphologies and calculation of the band gaps. Under illumination, the conduction band electrons of TiO2 are excited and accompanied by the generation of positive holes. In this heterostructure, the conduction band electrons of WO3 occupy the nearest valence band of TiO2 and then combine with the internal holes, inhibiting the flow of the electrons transferred from the conduction band of TiO2. Compared with anatase TiO2, the WO3-coated TiO2 heterostructure (weight ratio of WO3:TiO2 = 1:2) with a finer grain size exhibits excellent photocatalytic performance.