Preparation of g-C₃N₄ with High Specific Surface Area and Photocatalytic Stability

g-C₃N₄ with porous structure has been synthesized by a thermal polymerization method and its specific surface area regulated by changing the calcination temperature. The as-prepared g-C₃N₄ was characterized by x-ray diffraction (XRD) analysis, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–Vis) spectrophotometer. The photocatalytic activity of g-C₃N₄ was investigated using Methyl Orange (MO) as target pollutant. The results show that the g-C₃N₄ exhibited a unique porous structure with a specific surface area reaching 142.1 m²/g at 610°C. When the calcination temperature was 570°C, the specific surface area of g-C₃N₄ was 116.3 m²/g and the photodegradation rate of MO was 65%. Moreover, g-C₃N₄ retained good photocatalytic stability after being used for five times. The photocatalytic mechanism was also explored by free-radical scavenging experiments.