Preparation of ternary combined ZnO-Ag2O/porous g-C3N4 composite photocatalyst and enhanced visible-light photocatalytic activity for degradation of ciprofloxacin

In current work, a ternary combined ZnO-Ag 2 O/porous g-C 3 N 4 (ZnO-Ag 2 O/pg-C 3 N 4 ) composite photocatalyst was prepared and used for the degradation of ciprofloxacin (CIP) under visible light irradiation. The structure, surface morphology and chemical composition of as-prepared composite photocatalyst are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and Brunauer–Emmett–Teller (BET) methods. From the DRS and PL optical property test, the result indicated that ZnO-Ag 2 O/pg-C 3 N 4 presented relative narrow band gap and higher separation rate of photoinduced charge carriers in the ternary combined system, which was favorable for the photocatalytic activity enhancement under visible light irradiation. Compared with ZnO , porous g-C 3 N 4 , Ag 2 O and ZnO-Ag 2 O, the prepared ZnO-Ag 2 O/pg-C 3 N 4 presents the highest degradation efficiency (97.4%) within 48   min. The degradation intermediates of CIP were detected by HPLC/MS during photocatalytic degradation. Furthermore, porous g-C 3 N 4 as a visible-light-driven photocatalyst used as supporter in the combined system not only improves the degradation efficiency, but also speeds up the reaction rate.