Enhanced tetracycline degradation via effective electronic modulation of vacancy-defective S, O co-doped diatomic-layered g-C3N4 nanosheets

Rational design of graphitic carbon nitride (g-C 3 N 4 ) nanosheets through combined elemental doping and defect functionalization to optimize the photocatalytic performance remains a promising yet challenging strategy. In this study, sulfur/oxygen atoms and vacancy defects were engineered sequentially in CN nanosheets (CN-SO-v) through a dual approach of thermal polymerization and oxidative etching. The as-prepared CN-SO-v exhibiting atomically thin nanosheet architecture exposed abundant active sites accessible for catalytic processes. Under visible light irradiation, CN-SO-v exhibited exceptional photocatalytic activity , achieving complete degradation of tetracycline by 99.1% within just 15 min. The kinetics rate constant of CN-SO-v was 9.1 times higher than that of pristine CN . DFT calculations revealed that the incorporation of sulfur into CN induced lattice distortions attributed to its large atomic size and electron donor . The synergistic effects of defect engineering and co-doping promoted photogenerated exciton formation while substantially enhancing charge separation efficiency. • Vacancy-defective S/O-codoped CN(CN-SO-v) enables efficient photocatalysis. • DFT reveals S/O-codoping-defect synergy boosts photogenerated carrier separation. • CN-SO-v enables 99.1% tetracycline removal in 15 min under visible light.