Han Wenyuan, Li Degang, Zhang Manqi, Ximin Hu, Duan Xiaoguang, Liu Shaomin, Wang Shaobin
School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255000, P.R. China.
School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255000, P.R. China.
J Hazard Mater. 2020 Aug 5;395:122695. doi: 10.1016/j.jhazmat.2020.122695. Epub 2020 Apr 14.
In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs. The effects of catalyst dosage, species and concentrations of dyes, and initial pH values on the photodegradation efficiency were systematically investigated and the alkaline condition facilitates the separation of photoinduced charge carriers and promotes the dye decoloration. The reactive oxygen species produced in the photocatalysis were identified by radical quenching tests and the mechanism was elucidated. Superoxide radicals were generated from PMS activation via electron transfer from CQDs and played the primary role in organic oxidation. In addition, photogenerated holes on the valence band of CQDs also participated in the dye decomposition.
在本研究中，通过低成本且可扩展的方法合成了碳量子点（CQDs），并通过化学后处理对其氧官能团进行了精细调节。研究发现，CQDs可作为可见光响应型光催化剂用于活化过一硫酸盐（PMS）及修复水中有机染料。由于选择性去除了羧基并抑制了光生电子 - 空穴对的复合，苯肼修饰的CQDs（CQDs - PH）对亚甲基蓝的降解表现出高效率。系统研究了催化剂用量、染料种类和浓度以及初始pH值对光降解效率的影响，碱性条件有利于光生电荷载流子的分离并促进染料脱色。通过自由基猝灭试验鉴定了光催化过程中产生的活性氧物种并阐明了其机理。超氧自由基通过CQDs的电子转移从PMS活化中产生，并在有机氧化中起主要作用。此外，CQDs价带上的光生空穴也参与了染料分解。
