Photocatalytic degradation of chlorinated organic pollutants by ZnS@ZIF-8 composite through hydrogen peroxide generation by activating dioxygen under simulated sunlight irradiation

Yong Chen; Yong Liu; Xiaobo Gong; Jianlong Wang

doi:10.1016/j.jcis.2023.10.156

Photocatalytic degradation of chlorinated organic pollutants by ZnS@ZIF-8 composite through hydrogen peroxide generation by activating dioxygen under simulated sunlight irradiation

J Colloid Interface Sci. 2024 Jan 15;654(Pt B):1417-1430. doi: 10.1016/j.jcis.2023.10.156. Epub 2023 Oct 31.

Authors

Yong Chen¹, Yong Liu², Xiaobo Gong³, Jianlong Wang⁴

Affiliations

¹ College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, China.
² College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, China; Key Laboratory of Treatment for Special Wastewater of Sichuan Province Higher Education Process, Chengdu, 610066, Sichuan, China. Electronic address: liuyong75@sicnu.edu.cn.
³ College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, China; Key Laboratory of Treatment for Special Wastewater of Sichuan Province Higher Education Process, Chengdu, 610066, Sichuan, China.
⁴ Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084, China. Electronic address: wangjl@tsinghua.edu.cn.

PMID: 37918100
DOI: 10.1016/j.jcis.2023.10.156

Abstract

Photocatalytic hydrogen peroxide (H₂O₂) production and its application in advanced oxidation processes (AOPs) are regarded as low-cost and environmentally friendly wastewater treatment processes. Herein, by modifying a small amount of sulphide on the zeolitic imidazolate framework-8 (ZIF-8), a ZnS@ZIF-8 composite and used for photocatalytic H₂O₂ production to degrade chlorinated organic pollutants under simulated sunlight (SSL). ZnS@ZIF-8 composite could enhance the separation of photo-induced charge carriers, promote electron transfer from zinc sulphide (ZnS) to ZIF-8, which exhibited good selectivity for the two-electron oxygen reduction reaction (2e^--ORR) and two-electron water oxidation (2e^--WOR) pathways. Based on oxygen (O₂) activation, the developed ZnS@ZIF-8/O₂/SSL system could achieve 6.43 mmol/L H₂O₂ production within 150 min, which was approximately 8.66 and 10.36 times higher than that of the ZnS/O₂/SSL and ZIF-8/O₂/SSL systems, respectively. In the ZnS@ZIF-8/O₂/SSL system, the ORR, WOR and H₂O₂ photolysis led to the generation of hydroxyl radical (•OH), while the photochemical behavior of ZnS in ZnS@ZIF-8 composite resulted in the generation of active hydrogen (*H). Benefitting from the high concentration of H₂O₂ and the coexistence of redox species in the ZnS@ZIF-8/O₂/SSL system, various chlorinated organic pollutants could be dechlorinated and mineralized. In addition, a possible mechanism for photocatalytic H₂O₂ production was also proposed. Importantly, the proposed process did not involve an additional sacrificial agent or Fenton-like catalysts. This work provides insights into the potential application of ZnS@ZIF-8 composite for H₂O₂ production and wastewater treatment.

Keywords: Coexistence of redox species; Dichlorination; H(2)O(2) production; Water decontamination; ZnS@ZIF-8.