Synthesis and Visible Photodegradation Enhancement of CdS/mpg-C₃N₄ Photocatalyst

A series of visible-light-induced CdS/mpg-C₃N₄ nanocomposites were fabricated vis the solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy analysis. The results show that CdS nanoparticles are homogenously dispersed on the sheet of mesoporous g-C₃N₄. The CdS/mpg-C₃N₄ nanocomposites show much higher visible-light-driven photocatalytic activity than individual mpg-C₃N₄ and CdS for methylene blue (MB) and phenol degradation. The optimal CdS content with the highest photocatalytic activity is determined to be 40%, which is almost 6.4 and 1.6 times higher than that those of individual mpg-C₃N₄ and CdS for the degradation of MB, and 12.2 and 2.2 folds for the degradation of phenol. The enhancement in photocatalytic activity and stability should be assigned to the effective separation and transfer of photogenerated charges coming from the well-matched overlapping band-structure between mpg-C₃N₄ and CdS. Radical trap experiments show that both the holes and O·⁻₂ are main oxidative species of CdS/mpg-C₃N₄ for MB degradation under visible light irradiation. Finally, the possible mechanism for the enhancement of the visible light performance is proposed.