Tuning and Understanding of Layered 2D MoS2–MoO3 Interface for Enhanced Photocatalytic Activities

Abstract

Heterostructures composed of transition metal dichalcogenides (TMDs) and transition metal oxides (TMOs) are essential for a wide range of applications, including photocatalysis and optoelectronic devices. The interface between these materials plays a significant role in controlling bandgap, charge carrier dynamics and photocatalytic activity. Therefore, it is imperative to conduct a systematic study of interface formation and its impact on these parameters to enhance the efficiency of both photocatalysts and devices. In this work, the synthesis of layered MoO3–MoS2 heterostructure using the two-step chemical vapor deposition method is reported. The α-MoO3 is synthesized using vapor trapping technique, followed by sulfurization to form the heterostructure. The interfacial structures and evolution of MoO3 to MoS2 at the interface using XRD, Raman, HRTEM, and XPS are systematically investigated. Density functional theory based on the first-principle calculations shows that an additional layer, MoOS, within the MoO3–MoS2 heterostructure induces a type-II band alignment rather than a type-III alignment. Further, the heterostructure is utilized as a photocatalyst, which shows threefold increase in photocatalytic efficiency compared to pure MoO3, achieving the degradation of 5 ppm MB dye in just 20 min under visible light, with a rate constant of 0.11408 min⁻¹, following a type-II staggered heterojunction mechanism.