Microwave-assisted synthesis of CQDs/ZnO hollow microspheres for complete NOx oxidation under visible light

IF 6.3 2区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Journal of Environmental Sciences-china Pub Date : 2025-05-09 DOI:10.1016/j.jes.2025.05.018

Yan Liu , Xianjin Shi , Long Cui , Pengge Wang , Zhenbo Zhang , Li Chen , Zhenyu Wang

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Abstract

The development of ZnO-based composites with high charge separation and effective inhibition of toxic by-products is admirable for effective photocatalysis of nitrogen oxides (NO_x) oxidation. In this study, carbon quantum dots (CQDs)/ZnO hollow microspheres, synthesized through a rapid microwave-assisted method, achieved over a 30-fold higher NO_x removal efficiency compared to ZnO, with complete inhibition of NO₂ by-products and good durability. The enhanced photocatalytic activity was ascribed to the unique role of CQDs, as revealed by in-situ photoelectric techniques. Results demonstrated that the electron directional migration from ZnO to CQDs at the composite interface accounts for the enhanced charge separation. Active free radicals for NO_x oxidation were identified, and in-situ diffuse reflectance infrared Fourier transform spectroscopy analysis elucidated the conversion pathways of NO_x oxidation under visible light irradiation. This work sheds light on the mechanisms of electron transfer and charge separation at the composite interface, offering guidance for designing superior ZnO-based photocatalysts for complete NO_x removal.

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可见光下CQDs/ZnO空心微球的微波辅助合成

具有高电荷分离和有效抑制毒性副产物的zno基复合材料的开发是有效光催化氮氧化物（NOx）氧化的理想材料。在本研究中，通过快速微波辅助方法合成了碳量子点(CQDs)/ZnO空心微球，与ZnO相比，其NOx去除效率提高了30倍以上，并且完全抑制了NO2副产物，并且具有良好的耐久性。原位光电技术表明，CQDs具有独特的光催化活性。结果表明，电子在复合界面上从ZnO向CQDs的定向迁移是电荷分离增强的原因。通过原位漫反射红外傅立叶变换光谱分析，确定了NOx氧化的活性自由基，阐明了可见光照射下NOx氧化的转化途径。这项工作揭示了复合界面上电子转移和电荷分离的机制，为设计更好的完全去除NOx的zno基光催化剂提供了指导。

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来源期刊

Journal of Environmental Sciences-china 环境科学-环境科学

CiteScore

13.70

自引率

0.00%

发文量

6354

审稿时长

2.6 months

期刊介绍： The Journal of Environmental Sciences is an international journal started in 1989. The journal is devoted to publish original, peer-reviewed research papers on main aspects of environmental sciences, such as environmental chemistry, environmental biology, ecology, geosciences and environmental physics. Appropriate subjects include basic and applied research on atmospheric, terrestrial and aquatic environments, pollution control and abatement technology, conservation of natural resources, environmental health and toxicology. Announcements of international environmental science meetings and other recent information are also included.