Enhanced photocatalytic mechanism for the hybrid g-C3N4/MoS2 nanocomposite

Abstract

Here, we explore the enhanced photocatalytic mechanism for the hybrid g-C₃N₄/MoS₂ nanocomposites for the first time by performing extensive density functional theory calculations. The calculated band alignment between the g-C₃N₄ monolayer and MoS₂ sheets clearly reveals that the conduction band minimum and valence band maximum of the g-C₃N₄ monolayer are higher by about 0.83 eV and 0.15 eV respectively than those of the MoS₂ sheet. This predicted type-II band alignment ensures the photogenerated electrons easily migrate from the g-C₃N₄ monolayer to the MoS₂ sheet, and leads to the high hydrogen-evolution reaction activity. The charge transfer between MoS₂ and g-C₃N₄ results in a polarized field within the interface region, which will benefit the separation of photogenerated carriers. The calculated optical absorption curves verify that this proposed layered nanocomposite is a good light-harvesting semiconductor. Moreover, a g-C₃N₄ bilayer covering a MoS₂ sheet also displays desirable properties. These findings indicate that the MoS₂ sheet is a promising candidate as a non-noble metal co-catalyst for g-C₃N₄ photocatalysts, and also provide useful information for understanding the observed enhanced photocatalytic mechanism in experiments.