关键词: 钨酸铋, 光催化, 水热法, 氧空位, 四环素

Abstract:

Drug molecules such as TC and NOR in sewage have great harm to organisms. The photocatalytic process for treating organic pollutants has potential advantages such as energy saving and environmental protection. Two layered Bi₂WO₆ photocatalysts were prepared by hydrothermal method. The composition, structure and morphology of the photocatalysts were characterized by X-ray powder diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that Bi₂WO₆-1 was composed of multi-layer nanosheets, while Bi₂WO₆-2 had a frame-like structure formed by a single square sheet. Compared with Bi₂WO₆-1, the single-layer nanosheet structure of Bi₂WO₆-2 gave it a larger specific surface area, a smaller band gap width and a higher oxygen vacancy content. In the photocatalytic degradation experiment, Bi₂WO₆-2 catalyst had good adsorption and photocatalytic degradation activity for TC and NOR. Under the optimal reaction conditions, the degradation rate of tetracycline by Bi₂WO₆-2 catalyst can reach 85.5% and the reaction rate constant was 0.0156 min^-1. Combined with the calculation of effective carrier mass, it was found that the existence of oxygen vacancy in Bi₂WO₆ structure changed its electronic structure properties, making it have smaller m_e* and m_h* values and larger m_h*/m_e* ratio (1.81), which was conducive to increasing the photogenerated carrier separation efficiency. Therefore, the high photocatalytic activity of Bi₂WO₆-2 catalyst could be attributed to the synergistic effect of single-layer Bi₂WO₆ nanosheet structure and oxygen vacancy, which not only increased the visible light absorption intensity, reduced the band gap width and increased the active site, but also significantly improved the photogenerated carrier separation efficiency.

Key words: bismuth tungstate, photocatalysis, hydrothermal method, oxygen vacancy, tetracycline