Enhanced photocatalytic performance of carbon quantum dots/BiOBr composite and mechanism investigation

Novel carbon quantum dots (CQDs)/BiOBr composite photocatalysts have been constructed through a facile hydrothermal synthesis in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). Series of characterizations have been performed to confirm the uniform distribution of CQDs in BiOBr nanosheets and the synergistic effect for photocatalytic degradation organic pollutants between CQDs and BiOBr. The results show that 3.1 wt% CQDs/BiOBr photocatalyst possesses the best photocatalytic activity for the degradation of colorless antibiotic tetracycline (TC), endocrine disrupter bisphenol A (BPA) and dye rhodamine B (RhB), under visible light irradiation, which exhibited the highest photocatalytic performance. The enhanced photocatalytic performance for CQDs/BiOBr composites could be attributed to the wider optical absorption range and fast separation of photogenerated charge carriers after the introduction of CQDs. The key roles of CQDs for the enhanced photocatalytic activity of BiOBr have been discussed. A possible mechanism of CQDs/BiOBr on the enhancement of visible light performance was proposed.