3D flower-like In₂Se₃/Bi₂O₂CO₃ n-n scheme heterojunctions for visible-driven simultaneous degradation of multi-tetracyclines

The purification of tetracycline wastewater using visible-light-driven heterojunction catalysts is a promising approach. In this study, a n-n type heterojunction, In2Se3/Bi2O2CO3, is synthesised through a solvothermal method by combining band-matched semiconductors. The resulting hybrid has a 3D hierarchical structure with abundant mesopores, facilitating rapid mass transfer. Notably, 5% In2Se3/Bi2O2CO3 hybrids demonstrate enhanced photocatalytic efficacy for simultaneous degradation of tetracycline hydrochloride (TCH) under visible light, including TCH blends with chlortetracycline (CTC) and oxytetracycline (OTC). This enhancement originates from the heterojunction interface, narrowing the band gap, increasing visible light absorption by Bi2O2CO3 (BOC), and creating an inherent electric field between BOC and In2Se3, separating electron-hole pairs. Mechanistic analysis identifies h(+) and center dot O-2(-) radicals as primary contributors to the photocatalytic process, suggesting a plausible n-n mechanism. This innovative design shows promise for advancing hierarchical heterostructures in tetracycline removal.