Carbon nitride with grafted benzothiadiazole as electron acceptor and active site to promote exciton dissociation for metal-free photocatalytic N2 fixation

Donghui Cui; Xue Yang; Yu Liu; Yuexin Xiang; Fengyan Li

doi:10.1016/j.jcis.2025.02.016

Carbon nitride with grafted benzothiadiazole as electron acceptor and active site to promote exciton dissociation for metal-free photocatalytic N₂ fixation

J Colloid Interface Sci. 2025 May 15:686:795-806. doi: 10.1016/j.jcis.2025.02.016. Epub 2025 Feb 3.

Authors

Donghui Cui¹, Xue Yang¹, Yu Liu¹, Yuexin Xiang¹, Fengyan Li²

Affiliations

¹ Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024 PR China.
² Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun 130024 PR China. Electronic address: lify525@nenu.edu.cn.

PMID: 39922169
DOI: 10.1016/j.jcis.2025.02.016

Abstract

High photogenerated charge transfer efficiency and good N₂ adsorption/activation capability are key points to achieving photocatalytic ammonia synthesis. In this study, we choose 4-amino-2,1,3-benzothiadiazole (ABT) as an electron acceptor covalently grafted on the edge of graphitic carbon nitride (CN) to create a donor-acceptor (D-A) structure. This structure facilitates targeted electron transfer of photogenerated charge from the center to the edge. Among them, the 1-ABT-CN photocatalyst can reach an average NH₃ yield of 479.2 μmol g^-1h^-1 with excellent thermal and experimental cycling stability. Experimental tests and theoretical calculations demonstrate that the grafted benzothiadiazole as an electron acceptor can effectively inhibit photogenerated carrier recombination. Meanwhile, the S atom in the electron acceptor structure may be an active site for the adsorption and reduction of N₂ molecules. The variable-temperature photoluminescence spectroscopy, conducted within the range of 80-320 K, further demonstrates that 1-ABT-CN, with its donor-acceptor (D-A) structural unit, effectively reduces the exciton effect and promotes exciton dissociation, thereby enhancing photocatalytic activity compared to pristine CN. This work advances our understanding of intramolecular charge transfer in CN molecules and serves as a guide for the development of metal-free D-A-type CN photocatalysts.

Keywords: Ammonia; Benzothiadiazole; Donor–acceptor; Graphitic carbon nitride; Photocatalytic.