Reduced graphene oxide nanocomposites with different diameters and crystallinity of TiO2 nanoparticles - synthesis, characterization and photocatalytic activity

TiO2-reduced graphene oxide nanocomposites with different diameters and crystallinity of titania nanoparticles were synthesized via the sol-gel method followed by calcination in air or treatment under vacuum. The materials were characterized with transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence spectroscopy and diffuse-reflectance UV-vis spectroscopy. The photocatalytic activity of the resulting materials was examined in the process of phenol decomposition under UV-vis light irradiation. The influences of TiO2 loading and calcination treatment on photocatalytic activity of the composites were investigated. It was found that higher TiO2 concentrations resulted in higher photocatalytic activity. This is in agreement with the band gap energy values, as lower visible light absorption and higher E-g values were obtained for the samples prepared with higher TiO2 loading. Furtheimore, photoactivity was affected by the calcination treatment. Higher activity under UV-vis was shown by the samples calcinated under vacuum, which was attributed to the better crystallinity compared to the samples treated with air.