Synthesis of reduced graphene oxide functionalized with methyl red dye and its role in enhancing photoactivity in TiO2–IL/WO3 composite for toluene degradation

A nanostructured composite material was produced through sol–gel-assisted ionic liquid (IL) synthesized TiO2, WO3 and functionalized reduced graphene oxide (FRGO), respectively. IL was selected and used as shape and size controller in TiO2 synthesis as well. GO nanosheets were functionalized with (E)-2-[4-(dimethylamino) phenyl] benzoic acid (methyl red dye) in order to absorb more light. The products were characterized using X-ray diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption methods, FTIR, Raman, photoluminescence and X-ray photoelectron spectroscopy. The photocatalytic activity of TiO2–IL/WO3/FRGO composite in toluene degradation under visible-light irradiation was evaluated by gas chromatography. The prepared composite demonstrated significant toluene degradation (ca. 74%) after only 2 min of reaction in comparison to TiO2–IL/WO3 composite (51%), TiO2–IL (40%) and pure TiO2 (17%). These results are due to the combination of FRGO and WO3 with TiO2 by their properties like stability, high surface area and low band gap.