g-C3N4/TiO2-B{100} heterostructures used as promising photocatalysts for water splitting from a hybrid density functional study

Fabrication of heterostructures has been shown to be a good strategy to improve photocatalytic performance. By using first-principles calculation based on hybrid density functionals, the photocatalytic mechanism of g-C3N4/TiO2-B{100} heterostructures is investigated to understand the process of water decomposition. We find that the reduction of the band gap of g-C3N4/TiO2-B{100} heterostructures enhances the visible light response range. g-C3N4/TiO2-B{100} heterostructures have direct band gaps, staggered band alignment, electron flow from g-C3N4 to TiO2-B{100} surfaces and straddling water decomposition potential, and are potential Z-scheme photocatalysts. Photoinduced carriers can be effectively separated using the Z-scheme photocatalytic mechanism. Our results demonstrate that g-C3N4/TiO2-B{100} heterostructures can enhance light absorption, prolong the life of photoinduced carriers, and further improve the photocatalytic activity. We believe that our findings can provide a reference for explaining the enhancement mechanism of the g-C3N4/TiO2 photocatalyst as observed in the experiment.