Carbon quantum dot (CQD)-modified Bi₃O₄Br nanosheets possessing excellent photocatalytic activity under simulated sunlight

Carbon quantum dots (CQDs) modified Bi₃O₄Br (CQDs/Bi₃O₄Br) nanosheets were successfully synthesized through a mild hydrothermal method for the first time. Compared with traditional photocatalysts Degussa P25 and g-C₃N₄, the CQDs/Bi₃O₄Br composites exhibited better photocatalytic activity in degrading rhodamine B (RhB) under simulated sunlight, and the degradation rate of the composites could be increased by up to 4 times compared with the pure Bi₃O₄Br. In addition, the CQDs/Bi₃O₄Br composites also presented higher photocatalytic properties in degrading tetracycline hydrochloride (TC) and bisphenol A (BPA). The activity enhancement was attributed to the heterojunction structure formed by Bi₃O₄Br and CQDs, which could effectively separate photogenerated carriers. Two major active species, holes (h⁺) and superoxide radicals (•O₂⁻), were found in the process of photocatalysis. This work may provide a novel method for the environmentally friendly preparation of photocatalysts to remedy freshwater pollution.