Adsorption enhanced photocatalytic degradation sulfadiazine antibiotic using porous carbon nitride nanosheets with carbon vacancies

Residues of antibiotics are promoting antibiotic resistance of environmental microbiota which is identified as one of the most crucial global challenge for health security. Photocatalysis has been regarded as a desirable technology for organic pollutant removal, but is underappreciated in degradation of persistent organic pollutants due to the low adsorption capacity and photocatalytic efficiency of photocatalysts. In this study, a scalable photocatalyst of single/few-layered carbon nitride nanosheets with carbon vacancies (Cv-CNNs) is synthesized through a thermal process. Quantum mechanical simulation results reveal that the C vacancies can change the plane structure of CN sheets, enhancing adsorption capability of Cv-CNNs towards sulfadiazine (SDZ, a refractory antibiotic pollutant). Furthermore, the introduction of C vacancies in Cv-CNNs enhance the redox capacity, promoting photocatalytic hydrogen evolution and SDZ degradation. The removal efficiency of SDZ (5 mg L⁻¹) reaches almost 100% within 20 min under visible-light irradiation. In addition, the photocatalyst delivers a high H₂ evolution rate of 2.03 mmol h⁻¹ g⁻¹. The study provides a large-scale-production metal-free photocatalyst for practical application in antibiotics removal from wastewater or solar-to-hydrogen energy conversion.