Photochemical transformation of C3N4 under UV irradiation: Implications for environmental fate and photocatalytic activity

Yiping Feng; Mengyao Shen; Zhijie Xie; Ping Chen; Lin-Zi Zuo; Kun Yao; Wenying Lv; Guoguang Liu

doi:10.1016/j.jhazmat.2020.122557

Photochemical transformation of C₃N₄ under UV irradiation: Implications for environmental fate and photocatalytic activity

J Hazard Mater. 2020 Jul 15:394:122557. doi: 10.1016/j.jhazmat.2020.122557. Epub 2020 Mar 18.

Authors

Yiping Feng¹, Mengyao Shen², Zhijie Xie², Ping Chen², Lin-Zi Zuo³, Kun Yao², Wenying Lv², Guoguang Liu²

Affiliations

¹ Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China. Electronic address: ypfeng@gdut.edu.cn.
² Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.
³ Analysis and Test Center, Guangdong University of Technology, Guangzhou 510006, China.

PMID: 32272327
DOI: 10.1016/j.jhazmat.2020.122557

Abstract

In this study, the photo-transformations of bulk C₃N₄ (CN) and oxidized C₃N₄ (OCN) under UV-irradiation were examined. Through NO₃^- release measurements, we found that the photo-transformation rate of OCN is higher than that of CN. Various characterization results revealed the structural and chemical properties changes of CN and OCN after photo-transformation. We proposed that under reactive oxygen species attack, CN and OCN were gradually broken into smaller fragments and finally mineralized into NO₃-, CO₂, and H₂O through the circular reactions of deamination-hydroxylation-decarboxylation. Through the zeta potential measurements and sedimentation experiments, the influence of photo-transformation on the water stabilities of CN and OCN were assessed. The stability of CN in water increased while the water stability of OCN decreased after photo-transformation, implying that the changes to C₃N₄-based materials caused by photo-transformation may significantly impact their environmental behaviors. Moreover, the photocatalytic activities of the photo-transformed OCN and CN substantially decreased, indicating that the structural changes might be the main reason for their photocatalytic activity loss. These findings highlight the non-negligible influence of photo-transformation on the fate of C₃N₄ in aquatic environments, as well as on the photochemical stability during its use.

Keywords: C(3)N(4); Environmental fate; Oxidized C(3)N(4); Photo-transformation; UV irradiation.

Publication types

Research Support, Non-U.S. Gov't