WO3/TiO2 nanocomposites: Salt-ultrasonic assisted hydrothermal synthesis and enhanced photocatalytic activity

A series of WO3/TiO2 composite photocatalysts were fabricated via a facile salt-ultrasonic assisted hydrothermal process. The obtained samples were characterized by X-ray diffraction, scanning eletron microscopy, energy dispersive X-ray spectroscopy and UV-vis diffused reflectance spectroscopy. It was confirmed that anatase TiO2 and monoclinic WO3 coexisted in the composites. The photocatalytic activity of as-prepared WO3/TiO2 composites for degradation of Rhodamin B (RhB) under visible light irradiation was investigated. The results showed that WO3/TiO2 composites have a higher photocatalytic activity than those of pure TiO2 and pure WO3. First-principle calculations based on density functional theory were performed to explore the electronic structure and illustrate the photocatalytic mechanism of WO3/TiO2. The calculated energy gap was 2.53 eV, which was close to the experimental observation (2.58 eV). Due to the combination of WO3/TiO2, the photoinduced electrons and holes transfer between the WO3 and TiO2 in opposite directions, thus providing sufficient charge separation, which contributed to the photocatalytic activity enhancement.