Oxygen doping induced intramolecular electron acceptor system in red g-C₃N₄ nanosheets with remarkably enhanced photocatalytic performance

Abstract

The enhancement of the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) depends on the rational design of its visible-light harvesting and charge separation/migration properties. Herein, an oxygen doping-induced intramolecular electron acceptor system enabling n→π* electronic transitions in red g-C₃N₄ nanosheets (E_g ∼ 1.89 eV) was prepared via copolymerization with nitrilotriacetic acid (NTA) and urea. The n→π* electronic transition can be controllably tuned, thus broadening the absorption spectrum of the system to ∼750 nm. Simultaneously, doping with oxygen which acts as an electron acceptor, accelerates in-plane charge separation and migration. Moreover, this strategy was confirmed experimentally to be scalable for industrial mass production. Experiments and theoretical calculations demonstrated that the oxygen doping could continuously modulate the band gap (from ∼2.65 to ∼1.32 eV), resulting in the formation of an intramolecular electron acceptor system which enhances charge separation/migration kinetics. The optimized sample exhibited remarkable photocatalytic H₂ and H₂O₂ production rates of ∼144.8 µmol/h and ∼539.76 µM/h, respectively, which are higher than those for currently available g-C₃N₄-based photocatalysts. Significantly, the sample exhibited H₂ and H₂O₂ photocatalytic yields ∼37.3 and ∼30.1 times those of pristine g-C₃N₄ under long-wavelength excitation (λ = 520 nm). This study developed an effective and scalable strategy for the design and synthesis of full-spectrum photocatalysts for a broad range of applications.

Keywords

Oxygen doping / Red g-C₃N₄ nanosheets / Electron acceptor / n→π* electronic transition / H₂ and H₂O₂ production

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Huihui Gao: Writing - original draft, Data curation. Zhixin Yao: Validation, Data curation. Xuan Chen: Validation, Data curation. Mengqing Zhu: Validation, Software. Gang Zhao: Supervision, Project administration. Shouwei Zhang: Writing - review & editing, Writing - original draft, Supervision. Jinghua Guo: Writing - review & editing, Supervision.

Acknowledgements

This work was supported by the Natural Science Foundation of Shandong Province (Grant No. ZR2021ME143, ZR2020MA076).

Supplementary materials

Supplementary material associated with this can be found, in the online version, at doi:10.1016/j.chphma.2024.09.001.

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