Visible active reduced graphene oxide-BiVO4-ZnO ternary photocatalyst for efficient removal of ciprofloxacin

A highly effective rGO-BiVO4-ZnO photocatalyst was synthesized by hydrothermal method and characterized by XRD, FE-SEM, HR-TEM, XPS, Photoluminescence, FT-Raman, FT-IR and Diffuse reflectance spectroscopy. The narrow peaks of rGO-BiVO4-ZnO reveal good crystallinity and strong diffraction peaks of GO at 11.30 degrees and 42.43 degrees correspond to the layered structure of GO. Average crystalline size of the rGO-BiVO4-ZnO was 35 nm. TEM images reveal the presence of nanorods of ZnO and pristine structure of BiVO4 on the rGO sheet. The band gap energy for rGO-BiVO4-ZnO is 2.35 eV. The reduced PL emission at 524.6 nm by rGO-BiVO4-ZnO relative to the synthesized ZnO, reveal a decrease of recombination of the photon-induced electron-hole pair by loading of BiVO4 on ZnO. Ternary nanocomposite rGO-BiVO4-ZnO exhibits highest photodecomposition activity, achieving 98.4% decomposition efficiency for ciprofloxacin in 60 min under visible light irradiation. Photogenerated holes play a major role in the photocatalytic decomposition of ciprofloxacin (CIP), Low cost rGO-BiVO4-ZnO is stable and recyclable for effective decomposition of ciprofloxacin. Based on the GC-MS analysis, the CIP decomposition pathway as well as decomposition mechanism of piperazine ring oxidation are proposed. The photodecomposition efficiency is mainly due to charge transfer and excellent electron hole separation by doping of rGO.