TiO2 wrapped graphene as a high performance photocatalyst for acid orange 7 dye degradation under solar/UV light irradiations

Abstract

We have reported a simple strategy for the fabrication of titanium dioxide (TiO2)–graphene (GR) (TiO2–GR) nanocomposites towards improvement in the photocatalytic ability under both UV and solar light irradiations. The structural properties of the nanocomposite has been characterized by a series of techniques, including Fourier Transform Infrared (FTIR) spectroscopy, Raman Spectroscopy, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Scanning Electron Microscopy (TEM), UV–vis Diffuse Reflectance Spectra (UV-DRS), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Photoluminescence spectra (PL). The photocatalytic activity of the TiO2–GR nanocomposite catalyst was assessed by examining the degradation of acid orange 7 (AO7) dye from model aqueous solutions as a probe reaction under UV and solar light irradiations. Photodegradation experimental results indicated that the TiO2–GR nanocomposite catalyst exhibited higher photocatalytic activity than that of TiO2. The enhanced photodegradation activity might be mainly attributed to the role of GR played as electron acceptor and transporter in the composite film, which effectively suppressed the charge recombination and promoted the charge transfer within the composite. Moreover, organic compounds as intermediates of the degradation process were identified by ESI/MS. A possible reaction pathway for the degradation of AO7 was suggested by the evidence presented in this study.