Solvothermal synthesis of CDs/Bi4O5Br2 nanocomposites with improved visible-light photocatalytic ciprofloxacin (CIP) decontamination.

• CDs/Bi 4 O 5 Br 2 was synthesized via simple solvothermal method. • The absorption edge of 3 wt% CDs/Bi 4 O 5 Br 2 extended to 580 nm. • CDs/Bi 4 O 5 Br 2 showed enhanced photocatalytic activity. Carbon dots (CDs) and Bi-riched bismuth oxyhalide have great potential in the field of photocatalysis. Here, a series of CDs/Bi 4 O 5 Br 2 at different loading ratios were successfully synthesized by solvothermal method. Experiments of visible light degradation of ciprofloxacin (CIP) showed that 3 wt% CDs/Bi 4 O 5 Br 2 had the highest activity (5.39 times that of Bi 4 O 5 Br 2) and the degradation rate reached 98%. The samples were characterized by XRD, SEM, TEM, EDS, Mapping, UV–vis DRS, Raman, and PL spectra. The absorption edge of 3 wt% CDs/Bi 4 O 5 Br 2 was red-shifted from 455 nm to 580 nm compared with Bi 4 O 5 Br 2. The enhancement of photocatalytic activity was mainly due to the fact that the addition of CDs not only broadened the photo-response range, but reduced the recombination rate of photo-induced carriers with good electron transport interfaces formed. [ABSTRACT FROM AUTHOR]