In-situ microwave synthesis of graphene-TiO2 nanocomposites with enhanced photocatalytic properties for the degradation of organic pollutants

Graphene-titanium oxide (G-TiO2) nanocomposites were synthesized by a novel surfactant free, environmentally friendly one-port in-situ microwave method. The structure of the nanocomposite was characterized by the X-ray diffraction analysis and the morphology by using scanning electron microscopic and transmission electron microscopic images. The functional groups and carbon band structures were identified using FTIR and Raman spectral analysis. TiO2 nanoparticles in the size range of 5-10 nm were distributed on the graphene sheets. The surface area of pure TiO2 and G-TiO2 nanocomposite was measured to be 20.11 and 173.76 m(2)/g respectively. The pore volume and pore size of TiO2 were 0.018 cm(3)/g and 1.5266 nm respectively. G-TiO2 composite possesses higher pore volume (0.259 cm(3)/g) and pore size 3.2075 nm. The binding states of C, O and Ti of nanocomposite were analyzed by X-ray photoelectron spectroscopy, which confirmed the chemical bonding between graphene-TiO2. The photocatalytic activity of pure TiO2 and G-TiO2 nanocomposite was studied under UV and visible light irradiation sources with methylene blue dye. It has been observed that the degradation was faster in G-TiO2 nanocomposite than pure TiO2 nanoparticles. The rate constant and half life time were calculated from the kinetic studies of the degradation. The highest degradation efficiency of 97% was achieved in UV light and 96% for visible light irradiation with G-TiO2 as a catalyst. The studies reveal that G-TiO2 nanocomposite can be an effective catalyst for industrial waste water treatment. (C) 2016 Elsevier B.V. All rights reserved.