Establishing an S-scheme heterojunction is a promising method for increasing the photocatalytic activity of synthetic materials. In this study, nitrogen-doped g-C3N5/TiO2 S-scheme photocatalysts have been synthesized and examined for photocatalytic hydrogen production using thermal decomposition methods. Nitrogen-doped g-C3N5/TiO2 composites performed better than pure nitrogen-doped g-C3N5 and TiO2 alone. Using experiments and density functional theory (DFT) calculations, nitrogen (N) doping was identified as being introduced by replacing the carbon (C) atoms in the matrix of g-C3N5. In addition to its narrow band gap, N-doped g-C3N5 showed efficient carrier separation and charge transfer, resulting in the enhanced absorption of visible light and photocatalytic activity. DFT, XPS, optical property characteristics, and PL spectra confirmed these findings, which were attributed to the successful nitrogen doping, and the composite was proven to be a potential candidate for photocatalytic hydrogen generation under light irradiation. The quantity of H2 produced from the nitrogen-doped g-C3N5/TiO2 composite for 3 hours (3515.1 μmol g-1) was about three times that of N-doped g-C3N5. The H2 production percentage of the nitrogen-doped g-C3N5/TiO2 catalyst with Pt as the cocatalyst was improved by nearly ten times as compared to N-doped g-C3N5/TiO2 without a cocatalyst. Herein, we report the successful preparation of the N-doped g-C3N5/TiO2 S-scheme heterojunction and highlight a simple and efficient catalyst for energy storage requirements and environmental monitoring.
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