Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots

Wenyuan Han; Degang Li; Manqi Zhang; Hu Ximin; Xiaoguang Duan; Shaomin Liu; Shaobin Wang

doi:10.1016/j.jhazmat.2020.122695

Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots

J Hazard Mater. 2020 Aug 5:395:122695. doi: 10.1016/j.jhazmat.2020.122695. Epub 2020 Apr 14.

Authors

Wenyuan Han¹, Degang Li², Manqi Zhang¹, Hu Ximin¹, Xiaoguang Duan³, Shaomin Liu⁴, Shaobin Wang⁵

Affiliations

¹ School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255000, P.R. China.
² School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255000, P.R. China. Electronic address: ldg@sdut.edu.cn.
³ School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia. Electronic address: xiaoguang.duan@adelaide.edu.au.
⁴ College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
⁵ School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia.

PMID: 32330786
DOI: 10.1016/j.jhazmat.2020.122695

Abstract

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.

Keywords: Carbon quantum dots (CQDs); Oxygen groups; Peroxymonosulfate; Photocatalysis; Radicals; Superoxide.