TiO2/SGNs as photocatalyst for degradation of water pollutants

A novel photocatalyst, titanium dioxide/spherical graphene nodules (TiO2/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 TiO2/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 TiO2 was obtained, and TiO2 and SGNs were successfully combined. FT-IR and XPS results lend support to the proposed mechanism of formation of TiO2/SGNs composites through the bonding between oxygen vacancy sites in TiO2 (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 TiO2/SGNs composites were more effective under UV light than pure TiO2, 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 TiO2/SGNs composites could be employed as an efficient photocatalyst for the removal of textile dyes from effluents.