C-dots decorated SrTiO₃/NH₄V₄O₁₀ Z-scheme heterojunction for sustainable antibiotics removal: Reaction kinetics, DFT calculation and mechanism insight

Herein, we present an unprecedented feasible strategy for the removal of antibiotic residues in aqueous environments. A ternary C-dots/SrTiO₃/NH₄V₄O₁₀ catalyst was constructed by anchoring C-dots on the STO/NVO Z-scheme heterojunction by hydrothermal treatment. The synthesized catalyst was used for the degradation of sulfamethoxazole (SMX), aureomycin hydrochloride (CTC·HCl), and ciprofloxacin (CIP) under simulated solar light with the removal efficiencies of 94.7%, 88.3%, and 86.05% respectively, without significant inactivation even after four recycling experiments. Moreover, it shows application potential due to its superior removal efficiency towards the mixed antibiotics solution. The construction of Z-scheme heterojunction that exhibit good redox capacity and efficient charge transfer as well as the introduction of C-dots have a synergistic effect on the separation and migration of photogenerated carriers. Furthermore, the special 2D layered NH₄V₄O₁₀ nanosheets are favoring for the pre-adsorption of antibiotics molecules and provide more reaction sites. HPLC-MS, electron spin response (ESR), and density functional theory (DFT) calculations enabled the elucidation of the photocatalytic mechanism and possible degradation pathways. This study will provide a reference for designing efficient C-dots mediated Z-scheme heterojunctions to remediate broad-spectrum antibiotic residues.