Graphene Oxide and Graphene Oxide-TiO₂ Nanocomposites: Synthesis, Characterization, and Rhodamine B Photodegradation Investigation.

In this study, graphene oxide (GO) sheets were successfully synthesized using two routes: conventional Hummers' (HGO) and modified Hummers' (or Marcano's) (MGO) methods. GO sheets were then assembled with TiO₂ nanoparticles to form nanocomposites (i.e., HGO-TO and MGO-TO). The properties of HGO and MGO and their nanocomposites with TiO₂ were evaluated by Fouriertransform infrared (FTIR), Raman, ultraviolet-visible (UV-Vis) adsorption, and diffuse reflectance (DRS) spectroscopies, X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The specific surface area, pore volume, and pore size of MGO, determined by Brunauer-Emmett-Teller (BET) equation, were 565 m²g, 376 cm³ g, and 30 nm, respectively; all of these parameters decreased after MGO was combined with TiO₂. In addition, compared with HGO, MGO possessed higher oxidation level and more stable bonding with TiO₂ nanoparticles. The morphology of HGO and MGO, which were characterized by scanning electron (SEM) and transmission electron microscopies (TEM), together with energy-dispersive X-ray (EDX) spectroscopy and elemental mapping technique, was determined to consist of TiO₂ nanoparticle-assembled GO sheets. All GO-TiO₂ nanocomposite samples exhibited a very high activity (˜100%) toward rhodamine B (RhB) dye photodegradation under natural sunlight exposure within 60 min. The obtained results for the GO-TiO₂ nanocomposite showed the potential of its application in wastewater purification and other environmental aspects.