Surface atom rearrangement on carbon nitride for enhanced photocatalysis degradation of antibiotics under visible light

Recently, antibiotic pollution has aroused great concern due to its toxicity to living organisms and the risk of drug-resistance gene generation in the ecosystem. Carbon nitride (CN) photodegradation towards antibiotics is a promising technology for water purification. However, CN possesses a low activity due to the fast recombination of electron-hole pairs and slow reaction kinetics. Herein, we report the fabrication of nitrogen-vacancy and oxygen-substitution modified carbon nitride ((Nv, Os)–CN) with a rearranged surface via a low-temperature thermal oxidation strategy. The (Nv, Os)–CN can degrade tetracycline (TC), ciprofloxacin (CIP) and sulfadiazine (SZO) than CN under visible light irradiation efficiently. The first-order kinetic constant of (Nv, Os)–CN for TC, CIP and SZO was 2.1, 2.24 and 1.38 folds higher than those of CN, respectively. This high performance benefits from the rearranged surface atoms by forming an active surface with rich Nv and Os, thus promoting interfacial charge transfer and building robust water-(Nv, Os)–CN interface. In addition, the possible photodegraded pathways, resulting intermediates and risks of TC photodegradation were analyzed by the LC-MS and QSAR methods. Our proposed low-temperature thermal oxidation strategy to achieve surface atom rearrangement endows CN with an enhanced photoactivity toward antibiotics degradation.