Issue 2, 2022

Unraveling the dual defect sites in graphite carbon nitride for ultra-high photocatalytic H2O2 evolution

Abstract

Defect engineering modified graphite carbon nitride (g-C3N4) has been widely used in various photocatalytic systems due to the enhanced catalytic activity of multiple defect sites (such as vacancies or functional groups). However, the key mechanism of action in each defect site in the corresponding photocatalytic surface reactions is still unclear. Here, the –C[triple bond, length as m-dash]N groups and N vacancies were sequentially introduced into g-C3N4 (Nv–C[triple bond, length as m-dash]N–CN) for photocatalytic production of high-value and multifunctional H2O2, and the effect of dual defect sites on the overall photocatalytic conversion process was systematically analyzed. The modification of the dual defect sites forms an electron-rich structure and leads to a more localized charge density distribution, which not only enhances the light absorption and carrier separation capabilities, but also significantly improves the selectivity and activity of H2O2 generation. Importantly, detailed experimental characterizations and theoretical calculations clearly revealed the key role of each defect site in the photocatalytic H2O2 surface reaction mechanism: the N vacancies can effectively adsorb and activate O2, and the –C[triple bond, length as m-dash]N groups facilitate the adsorption of H+, which synergistically promote H2O2 generation. The Nv–C[triple bond, length as m-dash]N–CN reached a H2O2 generation rate of 3093 μmol g−1 h−1 and achieved an apparent quantum efficiency of 36.2% at 400 nm, significantly surpassing the previously reported g-C3N4-based photocatalysts. Meanwhile, a solar-to-chemical conversion efficiency of 0.23% was achieved in pure water. Constructing defects and understanding their crucial role provides significant insights into the rational use of defect engineering to design and synthesize highly active catalytic materials for energy conversion and environmental remediation.

Graphical abstract: Unraveling the dual defect sites in graphite carbon nitride for ultra-high photocatalytic H2O2 evolution

Supplementary files

Article information

Article type
Paper
Submitted
02 8 2021
Accepted
05 1 2022
First published
06 1 2022

Energy Environ. Sci., 2022,15, 830-842

Unraveling the dual defect sites in graphite carbon nitride for ultra-high photocatalytic H2O2 evolution

X. Zhang, P. Ma, C. Wang, L. Gan, X. Chen, P. Zhang, Y. Wang, H. Li, L. Wang, X. Zhou and K. Zheng, Energy Environ. Sci., 2022, 15, 830 DOI: 10.1039/D1EE02369A

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