Synthesis of TiO2/reduced graphene oxide–Al2O3 composites and their advanced properties for photocatalysis

The TiO2/reduced graphene oxide (RGO)-Al2O3 composites were synthesized by dispersing TiO2 on RGO-modified Al2O3 by impregnation method. The surface properties of TiO2/RGO–Al2O3 were systematically studied. It was found that the TiO2 particle size was about 15 nm, and the particles were relatively uniform in the loading range of 20–40 wt% compared with that of Al2O3. The surface area increased obviously as RGO was added to Al2O3. The chemical structures of the TiO2/RGO–Al2O3 composites were characterized by diffuse reflectance UV–Visible spectroscopy and X-ray photoelectron spectroscopy. Results revealed the presence of an intense interaction between TiO2 and RGO–Al2O3. The dark adsorption results showed that the TiO2/RGO–Al2O3 had a higher adsorption ability for methyl orange (MO), which was mainly due to the π-π conjugation between MO and RGO. The liquid-phase photocatalytic oxidation of MO was adopted to evaluate the efficiency of the obtained materials. TiO2/RGO–Al2O3 showed higher catalytic efficiency over the TiO2/Al2O3 or the commercial P25 photocatalyst. Recycling tests showed excellent stability of TiO2/RGO–Al2O3. The TiO2/RGO–Al2O3 was easier to separate by filtration method than TiO2 due to its high anti-hydration dispersion ability. The studies indicated their good prospects for large-scale application.