Facile Fabrication of N-Doped Graphitic Carbon-Modified g-C3N4 with Enhanced Photocatalysis Performance Under Visible Light Irradiation

For the first time, a series of N-doped graphitic carbon-modified g-C 3 N 4 samples were synthesized via thermal polycondensation by incorporating trace amounts of chitosan into melamine precursors. The photocatalytic performance of the samples was evaluated through Rhodamine B (RhB) degradation under visible-light irradiation. The photocatalyst prepared with 50 mg chitosan achieved complete degradation of 10 mg/L RhB within 30 min, outperforming pristine g-C 3 N 4 . After five consecutive cycles, the photocatalyst maintained 91% degradation efficiency within 30 min while preserving its original crystalline structure, demonstrating outstanding stability and reusability. The large specific surface area, enhanced electron transfer efficiency, extended visible light absorption and low photogenerated electron–hole recombination rate were considered to contribute to the extraordinary visible-light-driven (VLD) photocatalytic activity of N-doped graphitic carbon-modified g-C 3 N 4 . Furthermore, a scavenger study was conducted to identify the dominant reactive oxygen species (ROS) involved in the photocatalytic degradation of RhB, providing deeper insights into the underlying reaction mechanisms.