Synthesis and characterization of a g-C3N4/TiO2-ZnO nanostructure for photocatalytic degradation of methylene blue

In this study, graphitic carbon nitride (g-C3N4) nanostructures with different molar ratios of ZnO and TiO2 (i.e. g-C3N4/TiO2, g-C3N4/ZnO, and g-C3N4/TiO2-ZnO) were synthesized. The synthesized samples were characterized using field-emission scanning electron microscopy (FE-SEM), x-ray diffraction, Brunauer–Emmett–Teller (BET) analysis, and ultraviolet (UV)–visible diffuse reflectance spectroscopy (UV-vis-DRS) techniques. The FE-SEM images showed the surface morphology of each sample. The UV-vis-DRS results indicated that the bandgap of TiO2 was reduced by adding g-C3N4 and different molar ratios of ZnO. The results obtained from BET analysis confirmed that the surface area of the g-C3N4/TiO2-ZnO (1:10) nanostructure was 97.494 cm2 g−1, which was comparatively higher than other nanostructures, and became suitable for photocatalytic activity. The photocatalytic activity of the g-C3N4/TiO2-ZnO nanostructure was performed by photo-degradation of methylene blue (MB) dye under simulated solar light. The results of the photocatalytic activity showed that the synthesized nanostructure had good degradation under UV and visible light irradiation by 94.6% and 62.4%, respectively. Also, the kinetics of the photocatalytic degradation confirmed that degradation of MB dye in the presence of UV light was faster than visible light. Furthermore, a study of the reusability of the nanostructure exhibited good photo-stability and activity after six runs.