Synthesis of Tri-S-Triazine Based g-C₃N₄ Photocatalyst for Cationic Rhodamine B Degradation under Visible Light

In this research, graphitic carbon nitride (g-C₃N₄) photocatalysts were synthesized through a simple calcination process at various temperatures, which were 400, 500, 550, and 600 °C, by using low-cost urea as a precursor. The obtained g-C₃N₄ samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area and porosity analyses, and ultraviolet–visible-near-infrared (UV–VIS-NIR) spectroscopy. The correlations between the calcination temperature, properties, and photocatalytic activity of prepared products were investigated. The results demonstrated that the g-C₃N₄ photocatalysts can be successfully synthesized at temperatures of 500–600 °C with a controlled heating rate of 5 °C/min. In contrast, the intermediate product was observed in sample calcined at 400 °C. It was demonstrated that calcination at higher temperatures possibly increased the active sites and enhanced both of the photocatalytic activity and dye adsorption ability. Herein, the dye degradation efficiency (DE%) under visible light irradiation within 10 min were presented as 2.52, 16.01, 62.37, and 92.64% which were well developed as a function of calcination temperature from 400 °C, 500 °C, 550 °C, to 600 °C, respectively. Furthermore, the dye degradation rate could possibly induce decomposition pathway of rhodamine B. The photocatalytic efficiency was maintained after four times of reuse. It can be concluded that the thermal process plays an important role in controlling the properties and photocatalytic performance of g-C₃N₄.