Manipulation of n → π electronic transitions via implanting thiophene rings into two-dimensional carbon nitride nanosheets for efficient photocatalytic water purification

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2022-10, Vol.10 (38), p.20559-20570
• Main Authors: He, Fengting, Liu, Xiaoming, Zhao, Xiaoli, Zhang, Jinqiang, Dong, Pei, Zhang, Yang, Zhao, Chaocheng, Sun, Hongqi, Duan, Xiaoguang, Wang, Shaobin, Wang, Shuaijun
• Format: Article
• Language: English
• Subjects: Bisphenol A; Carbon; Carbon nitride; Copolymerization; Electric fields; Electron transitions; Electronic structure; Finite element method; Nanosheets; NMR; Nuclear magnetic resonance; Oxidation; Photocatalysis; Radiation; Radiation absorption; Transmission electron microscopy; Two dimensional analysis; Water purification; X-ray diffraction
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D2TA04975A

The photocatalytic performance of polymeric carbon nitride (C 3 N 4 ) is heavily restricted by insufficient n → π* electronic transitions and limited active sites. To this end, we adopted an integrated copolymerization and repyrolysis approach to fabricate two-dimensional thiophene ring implanted (C 3 N 4 ) nanosheets (2D Th ing -CNNS). Advanced characterization studies demonstrated that the fusion of thiophene rings and the formation of 2D nanosheets significantly collectively elevated the n → π* electronic transitions and enlarged the specific surface areas of 2D Th ing -CNNS, leading to a dramatically extended π-conjugated system and accelerated charge migration. Transmission electron microscopy, X-ray diffraction, and solid-state 13 C NMR proved the existence of the thiophene ring. Additionally, quantum computations of the highest occupied and lowest unoccupied crystal orbitals implied that the 2D Th ing -CNNS are more favorable for carrier migration than pristine (C 3 N 4 ). The finite element method (FEM) analysis indicates that 2D Th ing -CNNS have a stronger surface electric field and radiation absorption, which is consistent with the enhanced n → π* transition. Consequently, 2D Th ing -CNNS exhibit a 42.7-fold enhancement in photocatalytic performances for bisphenol A oxidation accordingly, compared with pristine C 3 N 4 . This work provides a novel strategy for engineering the electronic structure of C 3 N 4 for highly efficient water purification.