Novel assembly of homogeneous reduced graphene oxide-doped mesoporous TiO2 hybrids for elimination of Rhodamine-B dye under visible light irradiation

Abstract

Mesoporous TiO2 nanocrystals were hydrothermally synthesized and then dispersed in graphene oxide (GO) solution through ultrasonicated treatment. Visible light photocatalysts incorporating TiO2 nanocrystals and reduced GO (TiO2-rGO) were obtained by subsequent rapid solidification with liquid nitrogen, freeze-drying and heat treatment in flowing nitrogen. The resulting samples were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission election microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, diffuse reflectance ultraviolet–visible (DR UV–Vis) spectroscopy and nitrogen adsorption-desorption. Their adsorption capacity and visible light photocatalytic degradation activity in the elimination of rhodamine B (RhB) were evaluated at room temperature. The results showed that the mesoporous TiO2 nanoparticles were well dispersed onto rGO, leading to the enhanced adsorption of RhB and absorption of visible light. Consequently, the resulting TiO2-rGO hybrids showed outstanding efficiency for the elimination of RhB. Furthermore, the content of rGO had substantial influences on the photocatalytic performance of hybrids, which was the best for the hybrid with a content of rGO of 20% [TiO2-rGO(20)]. The adsorptive efficiency in the elimination of RhB dye with an initial concentration of 20.0 mg L−1 was as high as 66.7% and the photo-degradation efficiency may reach up to 81% under visible light irradiation over 10.0 mg of TiO2-rGO(20).