In situ construction bismuth oxycarbonate/bismuth oxybromide Z-scheme heterojunction for efficient photocatalytic removal of tetracycline and ciprofloxacin.

Finely engineering the morphology and regulating the hybrid interface of each component in a heterojunction are important for facilitating charge carrier separation. In this study, a flower-like bismuth oxycarbonate/bismuth oxybromide (BiOCO/BiOBr, BOC/BiOBr) Z-scheme heterojunction was prepared via generation of BOC followed by in situ self-growth of BiOBr on just generated BOC. The obtained photocatalyst has an interlaced nanosheet structure with oxygen vacancies, which enhances light adsorption and facilitates the migration and separation of charge carriers. The highest apparent rate constants (k) in the degradation of tetracycline and ciprofloxacin using the BOC/BiOBr-2 photocatalyst under visible-light irradiation were 0.0282 and 0.0220 min, respectively; these values were 6.1 and 6.2 times, respectively higher than that achieved using BOC as a photocatalyst. The hybrid mode of BOC and BiOBr, and the Z-scheme electron transfer path and oxygen vacancies present in BOC/BiOBr are the factors responsible for its high photocatalytic activity.