Enhanced photocatalytic activity of bismuth oxychloride by in-situ introducing oxygen vacancy

A series of samples of BiOCl-X (X = 0, 1, 3, 5) with abundant oxygen vacancies had been successfully synthesized through a facile solvothermal method, using bismuth nitrate (Bi(NO3)3·5H2O) and sodium chloride (NaCl) as raw materials, ethylene glycol as template and reductant. The formation of this structure of BiOCl can be attributed to the self-assembly multiple nanosheets. XRD, FT-IR, SEM, UV–Vis–DRS, EIS and other characterization methods were used to analyze the structure, morphology, photo-electrochemical analysis. Moreover, the oxygen vacancy generated in the samples were analyzed by XPS and ESR. The characterization results show that the single-phase BiOCl prepared by solvothermal method is tetragonal with abundant oxygen vacancies, which has large specific surface area and narrow band gap. Furthermore, Mott–Schottky curve shows from the side that with the extension of solvothermal reaction time, the semiconductor type of BiOCl can be converted from p-type to n-type, which may be related to the formation of oxygen vacancy. Compared with the original BiOCl nanosheets, the solvothermal reaction treated BiOCl with oxygen vacancy has better adsorption and photocatalytic performance, which is due to the narrower band gap caused by the introduction of defective energy levels. In addition, the degradation rate of tetracycline of BiOCl-1 was up to 90%. After three cycles, the visible light catalytic performance of BiOCl-1 was not decrease significantly, which was much better than the photocatalytic activity of BiOCl nanosheets.