Synthesis of Bi3O4Cl nanosheets with oxygen vacancies: The effect of defect states on photocatalytic performance

Bi3O4Cl and Bi3O4Cl-OV nanosheets with oxygen vacancies were successfully synthesized and detected using UV-visible diffuse reflectance spectra (DRS), X-ray photoelectron spectrometry (XPS) and Kelvin probes to explore the impact of the oxygen vacancies on the energy band structure. It is suggested that the defect states will shorten the forbidden band, close the distance between the Fermi level and the conduction band, and reduce the work function. All of these effects were confirmed by density functional theory (DFT) calculations and provide a reasonable explanation for the improvement of the photocatalytic performance of Bi3O4Cl-OV nanosheets. At the same time, Bi3O4Cl-OV was further modified by loading with the metal halide AgBr and the photocatalytic degradation efficiency was significantly improved approximately 11.2-fold compared to that of pure Bi3O4Cl nanosheets. This work not only offers efficient guidance for ascertaining the energy band structure of a semi-conducture but also provides tentative suggestions for improving photocatalytic performance via defect engineering.