Dramatic visible photocatalytic performance of g-C3N4-based nanocomposite due to the synergistic effect of AgBr and ZnO semiconductors

In this study, we synthesized a novel visible-light-driven photocatalyst with excellent photocatalytic activity, gC(3)N(4)/AgBr/ZnO, as a ternary nanocomposite for pollutant degradation via a facile method. This coupling was favorable due to charge transfer between the semiconductors to yield a Z-scheme photocatalysis system, and thus the separation of photo-excited electron-holes was improved. The structure, morphology, and optical properties of the photocatalyst were determined by using characterization techniques, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and its elemental mapping, N-2 adsoiption-desorption analysis, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence, fourier transform infrared spectra, and zeta potential measurements. The photocatalytic activity of the g-C3N4/AgBr/ZnO heterostructure was evaluated with different weight ratios during the degradation of the cationic pollutant methylene blue (MB) under exposure to visible light. The optimal photocatalyst with a g-C3N4 content of 30% exhibited superior activity during the degradation of MB and the rate constant of 0.041 min(-1) was about 4.6 times higher than the rate constant of the pure g-C3N4. In addition, we assessed the photosensitization of MB and its effect on the photodegradation process. We propose a possible mechanism to explain the photocatalytic activity of the prepared ternary nanocomposite based on experiments with reactive species scavengers. Finally, the reusability and stability of the photocatalyst was investigated after four cycles.