TiO2/SGNs as photocatalyst for degradation of water pollutants

Abstract

A novel photocatalyst, titanium dioxide/spherical graphene nodules (TiO 2 /SGNs) composites were prepared successfully by hydrothermal synthesis. SGNs were synthetized by simple thermal pyrolysis of methane in a chemical vapor deposition (CVD) reactor over home-made MgO from dolomite. The structure of TiO 2 /SGNs composites was investigated by scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and diffuse reflectance spectroscopy. The results showed that an anatase type TiO 2 was obtained, and TiO 2 and SGNs were successfully combined. FT-IR and XPS results lend support to the proposed mechanism of formation of TiO 2 /SGNs composites through the bonding between oxygen vacancy sites in TiO 2 (Ti-O-Ti bonds) and in-plane oxygen functional (epoxy) groups in SGNs possibly via Ti-O-C bonds. The photocatalytic activity on methylene blue (MB) degradation proved that TiO 2 /SGNs composites were more effective under UV light than pure TiO 2 , SGNs and dark reaction. Kinetic studies indicated that MB degradation followed Langmuir-Hinshelwood model better, the increase of the initial concentration of MB, the apparent reaction rate constant decreased. The results indicated that the TiO 2 /SGNs composites could be employed as an efficient photocatalyst for the removal of textile dyes from effluents.