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

摘要：

污水中的四环素（TC）、诺氟沙星（NOR）等药物类分子对生物体具有较大危害性，采用光催化技术处理有机污染物具有节能环保等潜在优势。通过水热法制备了两种层状Bi₂WO₆光催化剂，并利用X射线粉末衍射、扫描电子显微镜、X射线光电子能谱等技术对光催化剂的组成、结构和形貌进行表征。结果表明：Bi₂WO₆-1是由多层纳米片构成，而Bi₂WO₆-2为单层四方形片层形成的架状结构。与Bi₂WO₆-1相比，Bi₂WO₆-2单层的纳米片结构使其具有更大的比表面积、更小的带隙宽度以及更高的氧空位含量。在光催化降解实验中，Bi₂WO₆-2对TC和NOR表现出良好的吸附和光催化降解活性。在最优反应条件下，Bi₂WO₆-2对TC的降解率可达85.5%，反应速率常数是0.0156min^-1。结合载流子有效质量计算，得知Bi₂WO₆结构中氧空位的存在改变了其电子结构性质，使其具有更小的m_e*和m_h*值，以及更大的m_h*/m_e*比值（1.81），有利于增大其光生载流子的分离效率。因此，Bi₂WO₆-2具有较高光催化活性推测是由于单层Bi₂WO₆纳米片结构和氧空位的协同作用，这不仅增加了可见光吸收强度，缩小了带隙宽度，增加了活性位点，更显著提高了光生载流子的分离效率。

关键词: 钨酸铋, 光催化, 水热法, 氧空位, 四环素