Exfoliation method matters: The microstructure-dependent photoactivity of g-C3N4 nanosheets for water purification

Menglu Zhang; Yu Yang; Xiaoqiang An; Jingjing Zhao; Yueping Bao; Li-An Hou

doi:10.1016/j.jhazmat.2021.127424

Exfoliation method matters: The microstructure-dependent photoactivity of g-C₃N₄ nanosheets for water purification

J Hazard Mater. 2022 Feb 15;424(Pt B):127424. doi: 10.1016/j.jhazmat.2021.127424. Epub 2021 Oct 3.

Authors

Menglu Zhang¹, Yu Yang², Xiaoqiang An³, Jingjing Zhao⁴, Yueping Bao⁵, Li-An Hou⁶

Affiliations

¹ State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
² State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. Electronic address: yangyu@bnu.edu.cn.
³ Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
⁴ Academy of the Rocket Force, Beijing 100094, China.
⁵ Environment Chemistry and Materials Centre (ECMC), Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore.
⁶ State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; High Tech Inst Beijing, Beijing 100094, Peoples R China.

PMID: 34634708
DOI: 10.1016/j.jhazmat.2021.127424

Abstract

Exfoliation of carbon nitride (g-C₃N₄) into an ultrathin nanostructure significantly improves its photoactivity. However, the effects of the exfoliation method on the microstructure and photocatalytic performance of g-C₃N₄ nanosheets remain largely unknown. Herein, several typical strategies, such as thermal, chemical, ultrasonic and one-step exfoliation, were applied to exfoliate g-C₃N₄ nanosheets for photocatalytic applications. A procedure capable of controlling the morphology, microstructure, light-absorption property, and visible light photoactivity of g-C₃N₄ nanosheets was attempted. We found that nanosheets prepared from one-step exfoliation present superior photocatalytic efficiency under visible light than those fabricated by thermal exfoliation and ultrasonic exfoliation. The kinetic constants for bisphenol A (BPA) photodegradation over these samples were determined to be 6.5, 4.5 and 2.3 times higher than bulk g-C₃N₄, respectively. For chemical exfoliation, excessive oxidation by H₂SO₄ can lead to the structural defects and deactivation of urea-derived g-C₃N₄ nanosheets. Carbon nitride nanosheets synthesized by one-step exfoliation exhibited high specific surface area, optimal band gap energy structure, and high charge separation efficiency, thereby increasing visible-light photoactivity. Enabling cost-effective production of ultrathin and robust g-C₃N₄ nanosheets, one-step exfoliation offers a potential strategy to exploit high-performance g-C₃N₄ for water purification applications.

Keywords: Carbon nitride nanosheets; Exfoliation; Microstructure; Visible-light photocatalysis.