Citation: Haitao Ren, Zongcheng Miao, Xiangbo Feng, Abdelkader Labidi, Yuzhen Zhao, Chuanyi Wang. Modulating the built-in electric field of S-scheme heterojunction via oxygen vacancies for boosting photocatalytic ciprofloxacin degradation[J]. Chinese Chemical Letters, ;2026, 37(10): 112557. doi: 10.1016/j.cclet.2026.112557 shu

Modulating the built-in electric field of S-scheme heterojunction via oxygen vacancies for boosting photocatalytic ciprofloxacin degradation

Haitao Ren ^{a, b} ,
Zongcheng Miao ^c ,
Xiangbo Feng ^a ,
Abdelkader Labidi ^b ,
Yuzhen Zhao ^{a, *,} ,
Chuanyi Wang ^{b, d, *,}

a.
Shaanxi Key Laboratory of Liquid Crystal Polymer Intelligent Display, Technological Institute of Materials & Energy Science (TIMES), Xijing University, Xi’an 710123, China
b.
School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China
c.
School of Artificial Intelligence, Optics and Electronics (iOPEN), Northwestern Polytechnical University, Xi’an 710072, China
d.
Department of Environmental and Sustainable Engineering, Faculty of Engineering, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand

zyz19870226@163.com

wangchuanyi@sust.edu.cn

Received Date: 28 August 2025
Revised Date: 9 December 2025
Accepted Date: 26 February 2026
Available Online: 28 February 2026

Figures(7)

Developing S-scheme heterojunctions with a strong internal electric field (IEF) is crucial to facilitating charge separation and thereby enhancing catalytic activity. Herein, a 3D nanoflower-like oxygen vacancy (OV)-modified carbon quantum dot (CQD)/Bi₂WO₆ heterojunction was synthesized through a hydrothermal process followed by alkaline etching. The experimental and theoretical results demonstrate that the introduction of OVs optimizes the band structure of Bi₂WO₆ and increases the Fermi level difference between Bi₂WO₆ and the CQDs, thereby generating an enhanced interfacial IEF to boost the separation/migration of photoproduced charges. Quantitative analysis reveals that the IEF intensity of CQD/Bi₂WO₆-OV is 1.84 times greater than that of CQD/Bi₂WO₆. The S-scheme charge migration pathway between the CQDs and Bi₂WO₆-OV was elucidated via in situ X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR), which facilitates efficient charge separation and enhances the photocatalytic redox capability. As a result, the optimized CQD/Bi₂WO₆-OV S-scheme heterojunction exhibits a degradation efficiency of 95.2% for ciprofloxacin (CIP) within 40 min under visible light, and its kinetic rate constant is 3.4 and 30.8 times greater than that of Bi₂WO₆ and the CQDs, respectively. Furthermore, liquid chromatography-mass spectrometry (LC-MS) and Fukui function analyses elucidate the degradation mechanisms of CIP, and toxicity assessment confirms the low environmental risk of its intermediates. This work provides insights into the design of OV-engineered S-scheme heterojunctions for efficient charge separation and antibiotic photodegradation.
- Photocatalysis,
- Carbon quantum dot,
- Internal electric field,
- Oxygen vacancies,
- Bi₂WO₆,
- Antibiotic degradation
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