Synthesis and application of graphene-αMoO3 nanocomposite for improving visible light irradiated photocatalytic decolorization of methylene blue dye

Graphene-alpha-molybdenum trioxide (alpha-MoO3) nanocomposites were synthesized using a facile hydrothermal method. The synthesized material was characterized by various physico-chemical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), ultra-violet-visible diffuse reflectance spectroscopy (DRS) and Raman spectroscopy. Raman spectroscopy revealed a D to G band intensity ratio of approximately one, which confirmed the good graphitization of the synthesized graphene and graphene-MoO3 nanocomposite. The ID/IG ratio of the G-alpha MoO3 nanocomposite was calculated to be 1.2. HRTEM revealed graphene sheets decorated with MoO3 nanoparticles. The size of the MoO3 nanoparticles dispersed over the wrinkled graphene sheets layers was 10 +/- 5 nm. The chemical state functionality and composition (carbon, oxygen and molybdenum) of the G-alpha MoO3 nanocomposite was examined by XPS. TGA was performed to examine the thermal stability and decomposition of the nanomaterials and nanocomposite. The photocatalytic performance of the bare synthesized MoO3 nanoparticles and graphene-alpha MoO3 nanocomposite was analyzed by the degradation of MB dye under ultra-violet and visible light irradiation. The G-alpha MoO3 nanocomposite showed an extraordinarily higher photocatalytic activity than the bare MoO3 nanoparticles. Up to 97% and 96% of the MB dye was removed under UV and visible light irradiation, respectively. A comparison of the photocatalytic effect of the bare MoO3 and G-MoO3 nanocomposite showed that the bare MMoO3 induced less photocatalytic degradation than the G-MoO3 nanocomposite. The photocatalytic result suggested that graphene plays an important role in enhancing the photocatalytic activity. These results show that the G-alpha MoO3 nanocomposite is an efficient catalyst for the degradation of MB dye and has potential in industrial wastewater treatment. The mechanism of the degradation process was examined by calculating the rate constant and half-life of the degradation process. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.