Ga doped RGO–TiO2 composite on an ITO surface electrode for investigation of photoelectrocatalytic activity under visible light irradiation
Gallium (Ga) doped reduced graphene oxide–titania (RGO–TiO2) composites were successfully synthesized by a sol–gel method and deposited on an ITO coated glass substrate via an electrophoretic deposition method. The photocatalyst materials were tested in the CO2 conversion reaction in aqueous media. Prior to this, the catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis reflectance spectroscopy and Fourier transform infrared spectroscopy (FTIR). The synergistic effect of RGO and Ga doping on TiO2 was investigated. Electron–hole recombination on the catalyst surface can be minimized greatly by using RGO with TiO2 while Ga doping assists in reducing the band gap energy. The corresponding expansion of the absorption range towards the visible region was also observed. The results showed that both RGO and Ga enhance CO2 adsorption on the catalyst surface, hence facilitating a high CO2 conversion yield. The photoreduction products were mostly formic acid and trace amounts of methanol. A higher yield of formic acid was produced by the Ga–RGO–TiO2 composite films compared to the RGO–TiO2 composite and pure TiO2 film during a 120 min period of visible light irradiation.