Insights into the mechanism of the enhanced visible-light photocatalytic activity of a MoS2/BiOI heterostructure with interfacial coupling

Abstract

An understanding of the high photocatalytic performance reported for MoS₂/BiOI nanocomposite is far from satisfactory. Here, the interfacial interaction and electronic properties of a MoS₂/BiOI heterostructure were investigated systematically for the first time by first-principle calculations incorporating a semi-empirical dispersion-correction scheme. Our results confirm the reasonable existence of van der Waals interactions and a favorable Z-scheme mechanism, based on the typical interfacial cohesive energy and the energy level lineup at the interface. Analyzing the charge density differences and work functions, the built-in electric field is formed along the direction from MoS₂ to BiOI after the interface equilibrium, and facilitates the separation of photoinduced electron–hole pairs in the interface. Additionally, it can be inferred that the incorporation of MoS₂ into BiOI increases the carrier mobility and improves light harvesting, in agreement with the previously reported experimental data. Our work provides an insight into the mechanism of the enhanced visible-light photocatalytic activity of a MoS₂/BiOI heterostructure, and helps to design other new heterostructure combinations.