Enhanced photo-degradation of bisphenol a under simulated solar light irradiation by Zn-Ti mixed metal oxides loaded on graphene from aqueous media

In the present study, the mixed metal oxides (rGO-ZnTi-MMO-x, x presents weight percentage of GO) were obtained by thermal treatment of a Zn-Ti layered double hydroxides-graphene oxide (GO-ZnTi-LDHs) composite. rGO-ZnTi-MMOs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectra techniques. The photocatalytic activity of the obtained photocatalysts showed significantly enhanced activities in the degradation of bisphenol A (BPA). Compared with pristine ZnTi-MMOs, 88.12% of BPA at 10 mg L-1 was degraded using 0.5 g L-1 of rGO-ZnTi-MMO-2% as a catalyst under 3 h of simulated solar light irradiation. Photo-generated holes, OH and singlet oxygen radicals were demonstrated to be the predominant active species responsible for the photo-degradation of BPA. UV-vis diffuse reflectance spectra, photoluminescence spectra electrochemical impedance spectroscopy and transient photocurrent response of the photocatalyst confirmed that the enhanced photocatalytic activity of rGO-ZnTi-MMOs composites was attributed to the extended visible light absorption region and efficient transportation and separation of photo-induced electron-hole pairs of rGO-ZnTi-MMOs with unique hetero-nanostructure. Therefore, this work presents a facile method for the fabrication of a kind of graphene-based photocatalyst for water treatment.