1. Insight into photocatalytic chlortetracycline degradation by WO3/AgI S-scheme heterojunction: DFT calculation, degradation pathway and electron transfer mechanism.
- Author
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Wang, Chuantao, Li, Xiang, Lv, Xueting, Huang, Xin, Zhao, Yueyue, Deng, Tiantian, Zhang, Jiale, Wan, Jun, Zhen, Yanzhong, and Wang, Tuo
- Subjects
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ENERGY levels (Quantum mechanics) , *SPACE charge , *FERMI energy , *PHOTODEGRADATION , *REACTIVE oxygen species , *LIQUID chromatography-mass spectrometry , *CHARGE carriers - Abstract
The construction of S-scheme heterojunction with excellent redox ability holds promising prospects for photocatalytic environment remediation. However, the rationally design of the heterojunction interface to achieve efficient charge transfer still faces challenges. In this study, we fabricated a tight-contacted S-scheme heterojunction by in situ anchoring AgI nanoparticles onto WO 3 nanoplates. The significant difference in Fermi energy levels between WO 3 and AgI results in the formation of a space charge region around the interface and bending of the energy band, facilitating directional migration and spatial separation of charge carriers. This contributes to enhanced generation of superoxide radicals (•O 2 −) and holes (h+) active species, leading to a significant increase in chlortetracycline (CTC) degradation rate. The apparent rate constant for CTC removal using the WO 3 /AgI (WA-2) is approximately 15 times higher than that observed for pure WO 3. Furthermore, WA-2 exhibits universal degradation effects on tetracycline (TC) and oxytetracycline (OTC). Molecular dynamics (MD) simulation reveals the synergistic adsorption effect of WO 3 and AgI on CTC and reactive oxygen species molecules. Based on Fukui function calculation of CTC molecules and degradation intermediates, liquid chromatography-mass spectrometry (LC-MS) analysis, photocatalytic degradation pathway over WO 3 /AgI was determined to be sequential demethylation followed by dechlorination and decarbonylation. These findings provide valuable insights into high-performance S-scheme heterojunctions interface design and elucidation of pollutant degradation mechanism. The present study reports the fabrication of a well-aligned WO 3 /AgI S-scheme heterojunction for efficient degradation of CTC. The significant difference in Fermi energy levels between WO 3 and AgI leads to the formation of a space charge region at the interface, inducing band bending and facilitating directional migration as well as spatial separation of charge carriers. The WA-2 heterojunction exhibits exceptional degradation activity, stability, environmental compatibility for CTC, and universal photocatalytic performance against various tetracycline pollutants (TC, OTC). Furthermore, Fukui index calculation is employed to propose the most probable degradation pathway for CTC. [Display omitted] • Visible light-driven WO 3 /AgI heterojunction was synthesized by facile coprecipitation method. • WO 3 /AgI was confirmed to follow a S-scheme charge transfer mechanism. • WA-2 showed excellent photocatalytic degradation activity, stability and environmental suitability towards CTC. • The probable degradation pathway for CTC by WA-2 was analyzed by Fukui index calculation and LC-MS. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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