Efficient visible-light-driven photocatalytic hydrogen evolution and CO2 reduction over silver-modified tubular carbon nitride with enriched nitrogen vacancies

Yong Huang; Zhenjia Si; Tao Ding; Kun Zhou; Zhen Nie; Ying Zeng

doi:10.1016/j.envres.2025.122332

Efficient visible-light-driven photocatalytic hydrogen evolution and CO₂ reduction over silver-modified tubular carbon nitride with enriched nitrogen vacancies

Environ Res. 2025 Jul 10;285(Pt 1):122332. doi: 10.1016/j.envres.2025.122332. Online ahead of print.

Authors

Yong Huang¹, Zhenjia Si¹, Tao Ding², Kun Zhou¹, Zhen Nie², Ying Zeng³

Affiliations

¹ College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu, 610059, PR China.
² MNR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, PR China.
³ College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu, 610059, PR China. Electronic address: zengy@cdut.edu.cn.

PMID: 40645427
DOI: 10.1016/j.envres.2025.122332

Abstract

Enhancing the photogenerated charge pairs separation efficiency is one of the most effective strategies to improve the performance of graphitic carbon nitride (g-C₃N₄) in photocatalytic hydrogen evolution and CO₂ reduction. In this study, tubular g-C₃N₄ (TCN) with a high specific surface area was synthesized via thermal polycondensation-self-assembly, followed by the uniform deposition of Ag nanoparticles on the TCN surface to construct heterojunctions. During the reduction of Ag, a higher level of nitrogen vacancies was introduced on TCN, which not only enhanced the delocalization of electrons but also provided additional active sites for photocatalytic reactions. Performance evaluations reveals that the 1 % Ag/TCN sample exhibits the highest visible-light-driven hydrogen evolution efficiency, up to 2667 μmol g^-1·h^-1, with an apparent quantum yield (AQY) of 7.12 % under 420 nm monochromatic light irradiation. Furthermore, all modified samples demonstrate superior performance in photocatalytic CO₂ reduction, with the 1 % Ag/TCN sample achieving a CO evolution rate of 45.6 μmol g^-1, which is 5.18 times than that of the pristine TCN sample. This "structure-interface-defect" cooperative multi-scale optimization strategy significantly enhanced the photogenerated charge carriers separation and migration rates of g-C₃N₄, thereby improving the photocatalytic performance. This integrated approach provides a reliable and cost-effective pathway to address the inherent limitations of semiconductor-based photocatalysts.

Keywords: CO(2) reduction; Heterojunctions; Nitrogen vacancies; Photocatalytic hydrogen evolution; Tubular carbon nitride.