Binary WO3-ZnO nanostructures supported rGO ternary nanocomposite for visible light driven photocatalytic degradation of methylene blue

Novel graphene supported ternary nanocomposites (WO3-ZnO@rGO) were prepared via simple ultrasound assisted fabrication of WO3-ZnO binary nanostructures over 2D rGO nanosheets. Structural, morphological and elemental characterization of as-synthesized samples were carried out through X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and Energy dispersive X-ray spectroscopy (EDX). Optical band gap analysis under UV–vis spectroscopy (UV–vis) revealed a decrement in the band gap energy value of WO3-ZnO@rGO ternary nanocomposites. Current-voltage (I–V) measurements evidenced the ohmic response of rGO supported WO3-ZnO nanocomposites as compared to bare samples. To evaluate the photocatalytic efficiency of WO3-ZnO@rGO nanocomposites in comparison to bare nanostructures, wastewater organic pollutant methylene blue (MB) dye was chosen as benchmark reaction. Results suggested that impregnation of WO3-ZnO over rGO sheets significantly improved the photocatalytic efficiency of WO3-ZnO@rGO with 94 % dye removal within 90 min under visible light irradiation. The enhanced photocatalytic efficiency is ascribed to synergistic effects originating at WO3-ZnO@rGO interfaces subsidizing high quantum yield and effective separation and transfer of photo induced electron-hole pairs. Moreover, WO3-ZnO@rGO also retained its remarkable dye degradation efficiency even after four recycling tests.