Porous Na-doped g-C₃N₄ via supramolecular self-assembly for enhanced photocatalytic antibiotic removal and bacterial...

This study synthesizes dual-modified graphitic carbon nitride (CN) through morphological engineering and Na doping, synergistically enhancing visible-light absorption and charge carrier dynamics. A coral-like Na-doped CN (NaCCN) was fabricated via one-step calcination method, leveraging the self-assembly of melamine and cyanuric acid in NaCl solution. This strategy simultaneously improved the electronic structure of the catalyst skeleton, increasing active sites and boosting electron transfer efficiency. Characterization revealed that NaCCN exhibits broadened visible-light utilization, lower photogenerated carrier coincidence rate, and higher electron transfer rate. NaCCN achieved complete tetracycline hydrochloride (TC) degradation in 18 min, with a rate constant of 0.224 min^-1, which is 32 times faster than CN. It maintained high efficiency across TC concentrations (25-200 mg L^-1) and pH (1.6-11), with universal efficacy against multiple antibiotics. Structural integrity and reactivity were preserved over 10 cycles. Additionally, NaCCN inactivated ∼100 % of Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa within 60 min. Mechanistic studies combining band structure analysis, reactive oxygen species (ROS) trapping, and Liquid Chromatograph Mass Spectrometer (LC-MS) identified superoxide radical and photoexcited hole as dominant species, with TC degradation proceeding through hydroxylation, demethylation, and ring-opening steps. The dual modification strategy provides a scalable approach to design robust g-C₃N₄-based photocatalysts for environmental remediation.