Synthesis of graphitic carbon nitride/zinc oxide (g-C3N4/ZnO) hybrid nanostructures and investigation of the effect of ZnO on the photodegradation activity of g-C3N4 against the brilliant cresyl blue (BCB) dye under visible light irradiation

In the present study, g-C3N4/ZnO hybrid nanostructures were synthesized by mixing urea and zinc acetate as precursors via grinding and then microwave-assisted dehydration followed by a low-temperature calcination process. 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), high-resolution transmission electron microscopy (HRTEM), and UV-vis spectroscopic techniques. The effect of ZnO on the photocatalytic activity of g-C3N4 was investigated by considering the photodegradation of brilliant cresyl blue (BCB) dye over the fabricated g-C3N4/ZnO hybrid nanostructures under visible light irradiation. The g-C3N4/ZnO hybrid nanostructures obtained from the 4:1 weight ratio of urea and zinc acetate precursors denoted as g-C3N4/ZnO (20%) composite exhibited the greatest degradation efficiency in comparison to the other fabricated g-C3N4/ZnO hybrid nanostructures as well as to the pure ZnO and g-C3N4. In 60 min of visible light irradiation at pH (10), 99.51% of the BCB dye was mineralized. The photodegradation reaction data followed the pseudo-first-order kinetics model, and the kinetic rate constant (k) value for the degradation of BCB dye over the g-C3N4/ZnO (20%) hybrid nanostructure was calculated to be 0.08644 min(-1). The scavenger experiment results revealed that the electrons (e(-)) and superoxide (O-center dot (2)-) radical were the major reactive species involved in the degradation of BCB dye. Furthermore, the reusability experiments confirmed the good reusability and photostability of the g-C3N4/ZnO (20%) hybrid nanostructures after the four runs of recycles. The decrease in the catalyst performance even after four repeated cycles was determined to be only 4.5%. Thus, the present work provides an efficient and facile synthetic approach for the construction of g-C3N4/ZnO hybrid nanostructures which can be employed effectively for the photocatalytic degradation of organic water pollutants.