Enhanced Photocatalytic Performance of g-C3N4/TiO2 Heterojunctions through Sc, B Monodoping and Co-doping: A First-Principles Study

This study employed the first-principles method based on density functional theory to investigate the cell structure properties, electronic properties, and photocatalytic performance of g-C3N4/TiO2 heterojunctions, as well as Sc, B monodoped and co-doped g-C3N4/TiO2 heterojunctions. The results demonstrate that both TiO2 and g-C3N4 crystals exhibit good structural stability. The interaction between the g-C3N4 monolayer and the TiO2 (101) surface forms a van der Waals heterojunction, which possesses advantages such as a narrow bandgap, wide light response spectrum bandwidth, and high carrier migration efficiency. This effectively addresses the challenge of high energy consumption in the degradation process of organic pollutants. The heterojunction model, both before and after doping, is reasonable and feasible, featuring narrow bandgaps that effectively suppress the recombination of photo-generated electron-hole pairs. The interlaced band structure of the two crystals within the heterojunction promotes charge separation and carrier migration. The doping of Sc and B introduces hybrid states, not only regulating the redox ability but also further reducing the bandgap. Among these, co-doping exhibits the most significant effect, with a bandgap of 2.178 eV, accelerating charge transfer, causing a red shift in the absorption edge of the system, expanding the response range in the visible light region, enhancing absorption performance, and ultimately leading to superior photocatalytic performance.