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

• Published in: Journal of hazardous materials 2022-02, Vol.424, p.127424-127424, Article 127424
• Main Authors: Zhang, Menglu, Yang, Yu, An, Xiaoqiang, Zhao, Jingjing, Bao, Yueping, Hou, Li-an
• Format: Article
• Language: English
• Subjects: Carbon nitride nanosheets; Exfoliation; Microstructure; Visible-light photocatalysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127424

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. [Display omitted] •Exfoliation process influences the structure and photoactivity of g-C3N4 nanosheets.•A facile one-step exfoliation works best in the promotion of activity and yield.•The enhanced activity comes from improved band structure and surface area.•Chemical exfoliation via H2SO4 may cause structural defects and reduce activity.•We provide an insight for peers to simplify the g-C3N4 optimization procedure.