Environment-Friendly Carbon Quantum Dots/ZnFe 2 O 4 Photocatalysts: Characterization, Biocompatibility, and Mechanisms for NO Removal

作者：Yu Hong Huang, Yanling Liang, Yongfang Rao, Dandan Zhu, Jun-Ji Cao, Zhen-Xing Shen, Wingkei Ho, Shun Cheng Lee · 发表于：Environmental Science & Technology · 年份：2017 · DOI：10.1021/acs.est.6b04460 · 被引用次数：312 · 研究领域：Carbon and Quantum Dots Applications、Advanced Photocatalysis Techniques、Advanced Nanomaterials in Catalysis

A highly efficient and environmentally-friendly oxidation process is always desirable for air purification. This study reported a novel carbon quantum dots (CQDs)/ZnFe 2 O 4 composite photocatalyst for the first time through a facile hydrothermal process. The CQDs/ZnFe 2 O 4 (15 vol %) composite demonstrates stronger transient photocurrent response, approximately 8 times higher than that of ZnFe 2 O 4, indicating superior transfer efficiency of photogenerated electrons and separation efficiency of photogenerated electron–hole pairs. Compared with pristine ZnFe 2 O 4 nanoparticles, CQDs/ZnFe 2 O 4 displayed enhanced photocatalytic activities on gaseous NO x removal and high selectivity for nitrate formation under visible light (λ > 420 nm) irradiation. Electron spin resonance analysis and a series of radical-trapping experiments showed that the reactive species contributing to NO elimination were ·O 2 – and ·OH radicals. The possible mechanisms were proposed regarding how CQDs improve the photocatalytic performance of ZnFe 2 O 4 . The CQDs are believed to act as an electron reservoir and transporter as well as a powerful energy-transfer component during the photocatalysis processes over CQDs/ZnFe 2 O 4 samples. Furthermore, the toxicity assessment authenticated good biocompatibility and low cytotoxity of CQDs/ZnFe 2 O 4 . The results of this study indicate that CQDs/ZnFe 2 O 4 is a promising photocatalyst for air purification.