Synthesis of novel ternary heterojunctions via Bi2WO6 coupling with CuS and g-C3N4 for the highly efficient visible-light photodegradation of ciprofloxacin in wastewater

In this study, the novel Bi2WO6/CuS/g-C3N4 ternary heterojunctions with highly efficient visible-light photocatalytic performance were synthesized, which were then applying in the degradation of ciprofloxacin (CIP) in wastewater. The characterization data demonstrated that the heterojunction interfaces were formed between Bi2WO6, CuS and g-C3N4, which effectively narrowed the band gap. Moreover, coupling CuS with g-C3N4 inhibited the recombination of photogenerated e− and h+ pairs and accelerated the interfacial charge transfer; as a result, Bi2WO6/CuS/g-C3N4 possessed enhanced visible-light photocatalytic performance. Importantly, it has been confirmed that the photogenerated e−, h+ and O2− were main active species generated by Bi2WO6/CuS/g-C3N4 for photodegradation, which realized simultaneous redox reactions for the effective degradation of CIP (74.94 %, 75 min) and RhB (99.66 %, 90 min). Besides, the great chemical stability enabled Bi2WO6/CuS/g-C3N4 to maintain nearly the same photodegradation efficiency for CIP degradation after four repeated cycles. Taken together, this study provided not only a feasible method for synthesizing the novel Bi2WO6/CuS/g-C3N4 ternary heterojunctions with highly efficient visible-light photocatalytic performance, but also a way for purifying CIP in wastewater.