In situ ultrasound-assisted ion exchange synthesis of sphere-like AgClBr composites with enhanced photocatalytic activity and stability.

AgClBr composites with different halogen molar ratios (Cl/Br) were prepared by a facile ultrasound-assisted ion-exchange method. The formation of close contact between AgCl and AgBr facilitated the transportation of photoexcited charge carriers and contributed to the enhanced visible-light-driven photocatalytic degradation of different kinds of antibiotics. The AgClBr composites had a sphere-like morphology and tunable band gaps from 2.95 to 2.57 eV depending on Cl/Br mole ratios. Besides, the AgClBr composite was optimized by varying halogen mole ratios (Cl/Br) to achieve the highest photocatalytic activity. Results indicated that AgClBr showed the best photocatalytic degradation performance, which was about 2.36 and 2.78 times that of the single AgCl towards ciprofloxacin (CIP) and metronidazole (MNZ) degradation, respectively. Meanwhile, a possible photocatalytic degradation mechanism was discussed, and results indicated that the holes (h) and •OH were the dominant active species in the AgClBr system.