Facile synthesis of rod-like g-C3N4 co-doped with S, O, and Ce: interfacial modifications and charge transfer mechanisms for enhanced photocatalytic degradation of antibiotics

The development of efficient and stable photocatalysts is crucial for addressing environmental pollution and energy challenges. Graphitic carbon nitride (g-C₃N₄) has emerged as a promising photocatalyst; however, its practical application is hindered by low surface area, limited visible-light absorption, and rapid charge recombination. In this study, we synthesized S, O, and Ce co-doped rod-like g-C₃N₄ (SO/Ce-CN) via a facile molecular self-assembly method, achieving enhanced photocatalytic performance. Structural characterizations confirmed the successful incorporation of S, O, and Ce, leading to increased specific surface area, extended visible-light absorption, and improved charge separation efficiency. DFT calculations revealed that doping significantly improves charge transfer dynamics within the s-triazine rings. The degradation rate of oxytetracycline (OTC) for SO/Ce-CN under visible light irradiation reached 91.0 % within 90 min, which is 3.3, 2.1, and 1.4 times that of CN, Ce-CN, and SO-CN, respectively. Radical scavenging and ESR analyses identified ^[rad]O₂⁻ and h⁺ as the dominant reactive species. Furthermore, HPLC-MS/MS analysis revealed OTC degradation pathways, while TOC measurements confirmed effective mineralization. The catalyst demonstrated excellent stability and recyclability, maintaining high activity over six cycles. This study highlights the synergistic effects of S, O, and Ce co-doping, and provides new insights into designing efficient photocatalysts for antibiotic degradation.