Template Assisted Microwave Synthesis of rGO-ZrO₂ Composites: Efficient Photocatalysts Under Visible Light

In this research, cetyltetraethyl ammonium bromide template assisted microwave procedure was utilized to synthesize reduced graphene oxide-zirconia (rGO-ZrO₂) nanocomposites by varying the rGO composition (1, 2, 5 and 10 wt%). The physico-chemical characteristics of the nanocomposites were studied using X-ray diffraction (XRD), Raman, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), diffusive reflectance ultraviolet-visible (DRUV-vis), X-ray photoelectron spectroscopy (XPS) and N2-physisorption techniques. The results from XRD, Raman and DSC studies indicate that the increase in rGO concentration resulted in the delay in ZrO₂ crystallization temperature and alteration of ZrO₂ phase from monoclinic to tetragonal due to an effective incorporation of rGO nanosheets in ZrO₂ structure. The rGO loading also have an influence in the morphology of nanocomposites, as sample with 10 wt% rGO possessed unique monolith like morphology with macro pores. All the nanocomposites were utilized as photocatalysts for degradation of crystal violet dye in visible light irradiation. The rGO-ZrO₂ nanocomposites showed high reaction rates; the nanocomposite with 5 wt% rGO showed the superior photocatalytic performance as this sample possessed low band gap energy, high surface area, pore volume and presence of surface rGO-ZrO₂ interactive species as well as the reactive -OH groups. In addition, the synthesized nanocomposites exhibited excellent recyclability for photocatalytic degradation.