High-temperature continuous hydrothermal post treatment derived g-C3N4 for enhanced photocatalytic H2 production

Zhai, B. and Li, Y. and Jiang, Y. and Mao, L. and Shi, J. and Zhao, Q. and Bin, Z. and Wang, F. and Du, Y. and Jin, H. (2025) High-temperature continuous hydrothermal post treatment derived g-C3N4 for enhanced photocatalytic H2 production. Journal of Colloid and Interface Science, 685. pp. 1099-1108. ISSN 1095-7103

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Abstract

Nowadays, hydrothermal post treatment is a promising method for the modification of g-C3N4. This paper illustrates the post-treatment modification of g-C3N4 achieved by using a continuous hydrothermal system (CHS) with high heating rates (25–50 °C/s), short residence time (25.2–50.3 s), high reaction temperatures (250–300 °C) and high pressure (about 19 MPa). The continuous hydrothermal post treatment derived g-C3N4 (CHT-CN) prepared at 280 °C with 9 ml min−1 flow rate of g-C3N4 dispersion (CN-280/9) exhibits 5.6 times the photocatalytic H2-evolution activity of CN-30/9 under visible light irradiation (λ > 400 nm). Due to the exfoliation and shearing action of high-temperature and high-pressure water, the specific surface area of CN-280/9 reaches 65.8 m2 g−1, which is 4.3 times of CN-30/9 and therefore lead to an increase in reactive sites available for photocatalytic reactions. Moreover, the continuous hydrothermal post treatment results in the disruption of the conjugate structure of pristine g-C3N4 to build new channels, which allows more electrons to be transferred from bulk to surface to participate in the reduction reaction, and thus enhancing the H2-evolution activity. This work provides a valuable reference to potentially achieving the large-scale production of efficient photocatalysts based on the continuous high-temperature and high-pressure hydrothermal method.