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 envi-ronments. 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 ef-ficiency 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 photo-catalytic 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.

Automated summary

In this study, a novel method for removing antibiotic residues in water environments was proposed. A ternary C-dots/SrTiO3/NH4V4O10 catalyst was developed by constructing a hybrid heterojunction of C-dots and STO/NVO through hydrothermal treatment. The synthesized catalyst exhibited high efficiency in degrading sulfamethoxazole, aureomycin hydrochloride, and ciprofloxacin under simulated solar light, with removal efficiencies of 94.7%, 88.3%, and 86.05% respectively. The catalyst also showed great potential for removing mixed antibiotic solutions. The Z-scheme heterojunction with good redox capacity and efficient charge transfer, along with the introduction of C-dots, played a synergistic role in separating and migrating photogenerated carriers. The NH4V4O10 nanosheets provided pre-adsorption sites for antibiotic molecules, enhancing the removal efficiency. The photo-catalytic mechanism and possible degradation pathways were elucidated through HPLC-MS, ESR, and DFT calculations. This study provides insights for designing efficient C-dots mediated Z-scheme heterojunctions for broad-spectrum antibiotic residue remediation.