Titanium dioxide has been extensively investigated as a photocatalyst for water purification, presenting limitations such as recombination of electron-hole pairs generated by photons. The titania / graphene nanocomposites are promising materials to overcome these limitations due to the high specific area of graphene and unique electronic properties. In this work, an anatase-graphene nanocomposite was synthesized by a simple mixture assisted by ultrasound. Graphene was obtained by electrochemical exfoliation of graphite using the electrolysis technique. On the other hand, anatase was synthesized using the sol gel method. The obtained graphene, anatase and the nanocomposite material, were characterized with the X-ray diffraction technique (DRX), scanning electron microscopy (MEB) and transmission electron microscopy (MET). Using Raman spectroscopy, it was possible to verify that the graphite exfoliated correctly producing few layer-graphene. The lamellar nano-structure of the exfoliated graphite has crystallographic planes characteristic of graphite, graphene and graphene oxide. The presence of the anatase phase is shown in the diffraction spectrum of titania. The images obtained with SEM and TEM of the graphene sample show a layered lamellar structure and the TiO2 images show agglomerates of ellipsoidal nanoparticles. Obtained titania nanoparticles have a size of about 6 nm. Band gap value for such extremely low particle size nanocomposite is around 3.6 eV and presumably corresponds to the TiO2 (anatase) phase that completely surrounds the graphene. A nanocomposite model based on HRTEM observations is proposed. Considering the graphene electrical properties and the photocatalytic properties of TiO2, this nanocomposite promises to have applications in photocatalysis.
Synthesis and characterization of titania/graphene nanocomposite for application in photocatalysis
