C-Doped g-C₃N₄ for Enhanced Photocatalytic Degradation of Azo Dyes under Visible Light

A type of photocatalytic agent graphitic carbon nitride (g-C3N4) has been formed by the thermal polymerization of urea with citric acid, with various contents of C in its material (CN-x). Through the characterization of its morphology, structure, chemical composition, and photoelectric properties, it is found that the introduction of C dopant enhances sunlight absorption and facilitates electron-hole separation and charge transfer within the g-C3N4 structure. By further optimizing the doping amount of C, the photocatalytic degradation rates of CN-10 on Rh B, methylene blue and amaranth reached 97.2 %, 94.2 %, and 91.2 % within 40 min, which were 1.1 times, 1.3 times, and 2 times of the unmodified g-C3N4, respectively. Sacrifice experiments showed that & sdot;O-2- and & sdot;OH were the main active substances in the photocatalytic degradation of Rh B and amaranth. In the degradation of methylene blue, & sdot;O(2)(- )and h(+) were then the main active substances.