Graphene facilitated visible light photodegradation of methylene blue over titanium dioxide photocatalysts

Several graphene-titania composites (G-TiO2) were synthesized by a sal-gel method using titanium isopropoxide (or P25) as Ti-precursors and reduced graphene oxide (RGO). The structural, morphological, and physicochemical properties of the samples were thoroughly investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), UV-vis diffuse reflectance (UV-vis DRS), and thermogravimetric-differential thermal analysis (TG-DTA). A significant increase in light absorption to visible light was observed by G-TiO2 compared with that of naked TiO2. The photocatalytic activity of G-TiO2 in methylene blue bleaching under visible light (>430 nm) is much enhanced. G-TiO2 synthesized from titanium isopropoxide hydrolysis presented higher activity than that of G-TiO2(P25). Contribution of graphene on the enhancement of visible-light photocatalytic activity of the composite was discussed. (C) 2012 Elsevier B.V. All rights reserved.