Interfacial engineering of a plasmonic Ag/Ag2CO3/C3N5 S-scheme heterojunction for high-performance photocatalytic degradation of antibiotics

Abstract

Devising S-scheme heterostructure is considered as a cutting-edge strategy for advanced photocatalysts with effectively segregated photo-carriers and prominent redox potential for emerging organic pollutants control. Herein, an S-scheme Ag₂CO₃/C₃N₅ heterojunction photocatalyst was developed via a simple in situ chemical deposition procedure, and further photoreduction operation made metallic Ag (size: 3.5–12.5 nm) being in situ formed on Ag₂CO₃/C₃N₅ for a plasmonic S-scheme Ag/Ag₂CO₃/C₃N₅ heterojunction photocatalyst. Consequently, Ag/Ag₂CO₃/C₃N₅ manifests pronouncedly upgraded photocatalytic performance toward oxytetracycline degradation with a superior photoreaction rate constant of 0.0475 min^‒1, which is 13.2, 3.9 and 2.2 folds that of C₃N₅, Ag₂CO₃, and Ag₂CO₃/C₃N₅, respectively. As evidenced by comprehensive characterizations and density functional theory calculations, the localized surface plasmon resonance effect of metallic Ag and the unique S-scheme charge transfer mechanism in 0D/0D/2D Ag/Ag₂CO₃/C₃N₅ collaboratively strengthen the visible-light absorption, and facilitate the effective separation of powerful charge carriers, thereby significantly promoting the generation of reactive species like ·OH^–, h⁺ and ·O₂^– for efficient oxytetracycline destruction. Moreover, four consecutive cycles demonstrate the reusability of Ag/Ag₂CO₃/C₃N₅. Furthermore, the authentic water purification tests affirm its practical application potential. This work not only provides a candidate strategy for advancing S-scheme heterojunction photocatalysts but also makes a certain contribution to water decontamination.