Effect of microwave power on created defects in graphene sheet of synthesized TiO2/graphene nanocomposite with enhanced photocatalytic performance

Abstract

Nanocomposites of titanium dioxide and reduced graphene oxide (RGO), was prepared with a fast and simple microwave irradiation method by the reaction of graphene-oxide and commercial TiO2 nanoparticles in water/ethanol solvent. In a comparative study we examined different microwave powers 270W, 450W, 720W, and 900W with different time intervals for each case to find the effect of time and power on absorption wavelength and the creation of defects in graphene layer systematically. We found an optimum irradiation time in which the nanocomposite has the highest absorption wavelength (the smallest band gap), and the optimum value for microwave power in which the nanocomposite has the lowest amount of defect. First, graphite-oxide was prepared using modified Hummer's method and then we used TiO2 and the mixture of water/ethanol and graphene-oxide (GO), for hydrolysis of TiO2 followed by its mounting on graphene-oxide. We used microwave irradiation to produce TiO2/RGO nanocomposite in a way that microwave irradiation reduced graphene-oxide to graphene and created TiO2/RGO nanocomposite. Also we showed TiO2/RGO has a higher photocatalytic activity compared to pure TiO2. Characterization has been done by X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopy to support our results.