Impact of nitrogen doping on triazole-based graphitic carbon Nitride-TiO2 (P25) S-scheme heterojunction for improved photocatalytic hydrogen production

Abstract

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.