Fabrication of g-C3N4/ZnO Nanoheterostructures for Effective Degradation of Methylene Blue Dye under Visible Light Irradiation

Abstract In the present, the g-C3N4/ZnO hybrid nanoheterostructures photocatalysts with different weight percents of ZnO have been successfully prepared by a facile grinding, dehydration followed by pyrolysis method. The structural and textural properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy combine electron dispersive spectroscopy (FESEM-EDS) and UV-vis spectroscopy. The photocatalytic performance of the fabricated g-C3N4/ZnO nanostructures was investigated for the degradation of methylene blue (MB) dye and it is determined much higher in compare to the bare g-C3N4 nanosheets and ZnO nanorods. The optimized ZnO content in the g-C3N4/ZnO photocatalyst was determined to be 25%. In the current study, 99.54% of MB dye is degraded in 60 min of visible light irradiation at pH = 10 over g-C3N4/ZnO (25%) photocatalyst. The results of the kinetic study reveals that photodegradation reactions have followed the first-order kinetics and the rate constant values of MB photodegradation in presence of prepared g-C3N4/ZnO (25%) is determined ∼13 and ∼7.76 times greater than that of the bare g-C3N4 and ZnO respectively. The enhanced photocatalytic efficiency of the fabricated g-C3N4/ZnO nanoheterostructures could be due to the creation of heterojunction by the coupling of two semiconductors of well matched band structures in which effective charge transfer has been occurred. The prepared g-C3N4/ZnO has demonstrated significant photostability after utilization in four runs of cycles. The decrease in the catalyst performance even after four repeated cycles is approximately 8%. The superoxide free radicals (•O2−) are the main reactive species participated in the degradation of MB dye. The current approach of fabrication of heterojunction has presented a competent and simplistic synthetic tactic of creation of visible-light-driven photocatalyst for the effective photocatalytic mineralization of organic dye contaminants in the aqueous medium.