Construction of Z-Scheme g-CN/RGO/WO with in situ photoreduced graphene oxide as electron mediator for efficient photocatalytic degradation of ciprofloxacin.

Z-scheme photocatalyst g-CN/RGO/WO with reduced graphene oxide (RGO) as the electron mediator was synthesized via a facile photoreduction method. According the results of photoluminescence (PL), electrochemical impedance spectroscopy (EIS) and photocurrent response, g-CN/RGO/WO presents more efficient separation of charges and enhanced electronic mobility than g-CN/WO, g-CN and WO, which benefits from the excellent electron transfer property of RGO. Reactive species trapping experiments and electron paramagnetic resonance (EPR) test demonstrated that superoxide radical (O) and hydroxyl radical (OH) were produced because of the high redox capacities caused by the unique transfer behaviors of charges in Z-scheme photocatalyst g-CN/RGO/WO. In the absence of RGO as electron mediator, only holes (h) participates the degradation process of ciprofloxacin (CIP) due to the decreased redox capacities of g-CN/WO compared with g-CN/RGO/WO. Therefore, the degradation rate of Ciprofloxacin (CIP) over g-CN/RGO/WO composite was nearly twice as much as that over g-CN/WO. In addition, the analysis of intermediates provides insight into the degradation pathway of CIP.