Construction of polymeric carbon nitride and dibenzothiophene dioxide-based intramolecular donor-acceptor conjugated copolymers for photocatalytic H2 evolution

• Published in: Nanoscale advances 2021-03, Vol.3 (6), p.1699-1707
• Main Authors: Yu, Fengtao, Wang, Zhiqiang, Zhang, Shicong, Wu, Wenjun, Ye, Haonan, Ding, Haoran, Gong, Xueqing, Hua, Jianli
• Format: Article
• Language: English
• Subjects: Chemistry
• ISSN: 2516-0230; 2516-0230
• DOI: 10.1039/d0na01011a

Polymeric carbon nitride (g-C3N4) has succeeded as a striking visible-light photocatalyst for solar-to-hydrogen energy conversion, owing to its economical attribute and high stability. However, due to the lack of sufficient solar-light absorption and rapid photo-generated carrier recombination, the photocatalytic activity of raw g-C3N4 is still unsatisfactory. Herein, new intramolecular g-C3N4-based donor-acceptor (D-A) conjugated copolymers have been readily synthesized by a nucleophilic substitution/condensation reaction between urea and 3,7-dihydroxydibenzo[b,d]thiophene 5,5-dioxide (SO), which is strategically used to improve the photocatalytic hydrogen evolution performance. The experimental results demonstrate that CNSO-X not only improves light utilization, but also accelerates the spatial separation efficiency of the photogenerated electron-hole pairs and increases the wettability with the introduction of SO. In addition, the adsorption energy barrier of CNSO-X to H* has a significant reduction via theoretical calculation. As expected, the CNSO-20 realizes the best photocatalytic H2 evolution activity of 251 μmol h-1 (50 mg photocatalyst, almost 8.5 times higher than that of pure CN) with an apparent quantum yield of 10.16% at 420 nm, which surpasses most strategies for the organic molecular copolymerization of carbon nitride. Therefore, this strategy opens up a novel avenue to develop highly efficient g-C3N4 based photocatalysts for hydrogen production.Polymeric carbon nitride (g-C3N4) has succeeded as a striking visible-light photocatalyst for solar-to-hydrogen energy conversion, owing to its economical attribute and high stability. However, due to the lack of sufficient solar-light absorption and rapid photo-generated carrier recombination, the photocatalytic activity of raw g-C3N4 is still unsatisfactory. Herein, new intramolecular g-C3N4-based donor-acceptor (D-A) conjugated copolymers have been readily synthesized by a nucleophilic substitution/condensation reaction between urea and 3,7-dihydroxydibenzo[b,d]thiophene 5,5-dioxide (SO), which is strategically used to improve the photocatalytic hydrogen evolution performance. The experimental results demonstrate that CNSO-X not only improves light utilization, but also accelerates the spatial separation efficiency of the photogenerated electron-hole pairs and increases the wettability with the introduction of SO. In addition, the adsorption energy barrier of CNSO-X to H* has a significant reduct