Efficient band structure tuning, charge separation, and visible-light response in ZrS2-based van der Waals heterostructures

Abstract

As a fast emerging topic, van der Waals heterostructures can modify two-dimensional (2D) layered materials with desired properties, thus greatly extending the applications of these materials. Via state-of-the-art first-principles calculations, we systematically study four types of van der Waals heterostructures formed by monolayer graphene, h-BN, g-C₃N₄, and polyphenylene on ZrS₂ nanosheets. A direct band gap can be obtained in the graphene/ZrS₂ heterostructure, endowing graphene with the real ability to be applied in nanoelectronics, whereas the van der Waals interactions of graphene significantly broadens the optical absorption of ZrS₂. The conduction band and valence band of the four heterostructures are contributed by the ZrS₂ layer and the other layer, respectively, meaning good charge separation is achieved. We proposed that the strained h-BN/ZrS₂ and g-C₃N₄/ZrS₂ heterostructures satisfy fundamental aspects for photocatalytic water splitting, with the reduction and oxidation levels well inside their band gaps. By forming heterostructures with ZrS₂, the optical properties of h-BN, g-C₃N₄ and polyphenylene show a remarkable improvement in the visible-light region. The findings in this study will be of broad interest in van der Waals heterostructure research and in the photocatalysis field.