Visible light-driven photocatalytic degradation of rhodamine B and industrial dyes (texbrite BAC-L and texbrite NFW-L) by ZnO-graphene-TiO2 composite

Abstract

Visible light-responsive ZnO-graphene-TiO2 (ZGT) composite catalyst was successfully synthesized via a simple solvothermal process. The intrinsic characteristics of as-obtained samples were examined using a variety of techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The band gap energies of the samples were evaluated by UV–vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activities of as-obtained catalysts were assessed based on the degradation of rhodamine B (RhB), texbrite BAC-L (TBAC) and texbrite NFW-L (TNFW) under visible-light irradiation. ZGT exhibited higher visible-light-activated photocatalytic activity than did other samples (ZGT (7.97×10−4min−1)>ZG (3.43×10−4min−1)>graphene (2.43×10−4min−1)>TiO2 (2.22×10−4min−1)>ZnO (1.87×10−4min−1)). In addition, ZGT showed higher enhanced photocatalytic degradation of RhB than did other dyes (RhB (7.97×10−4min−1)>TNFW (5.20×10−4min−1)>TBAC (2.48×10−4min−1)). It is therefore evident that the synthesized ZGT can be used as a high performance catalyst for dye wastewaters. Moreover, the detailed photocatalytic mechanism of the photodegradation process is discussed.