Lamellar WO3/AgI S-scheme heterojunction for superior visible light driven photocatalytic degradation of ciprofloxacin

A unique lamellar WO 3 /AgI S-scheme heterojunction is constructed via integrated hydrothermal and coprecipitation methods. Optimized WO 3 /AgI composite shows significantly enhanced photocatalytic ciprofloxacin (CIP) degradation under visible light irradiation, achieving a removal rate of 53.4 % within 3 h, which is about 7.63 and 1.56 times superior than those of pristine WO 3 and AgI, respectively. The characterizations, experiment results and Density Functional Theoretical (DFT) calculation results confirm the enhanced light absorption, well-aligned straddling band structures and reasonable formation of S-scheme heterojunction with efficient photogenerated carriers transfer between WO 3 and AgI. Moreover, O 2 − and h + are identified as the main active species, with O 2 − plays a dominant role in WO 3 /AgI during the photocatalytic degradation of CIP. This work elucidates a possible approach to develop photocatalysts with a high antibiotic removal efficiency through a higher reducing ability and stronger oxidizing ability of S-scheme heterojunction by reasonable structure configuration.