Defect assisted coupling of a MoS₂/TiO₂ interface and tuning of its electronic structure

Although MoS₂ based heterostructures have drawn increased attention, the van der Waals forces within MoS₂ layers make it difficult for the layers to form strong chemical coupled interfaces with other materials. In this paper, we demonstrate the successful strong chemical attachment of MoS₂ on TiO₂ nanobelts after appropriate surface modifications. The etch-created dangling bonds on TiO₂ surfaces facilitate the formation of a steady chemically bonded MoS₂/TiO₂ interface. With the aid of high resolution transmission electron microscope measurements, the in-plane structure registry of MoS₂/TiO₂ is unveiled at the atomic scale, which shows that MoS₂[1-10] grows along the direction of TiO₂[001] and MoS₂[110] parallel to TiO₂[100] with every six units of MoS₂ superimposed on five units of TiO₂. Electronically, type II band alignments are realized for all surface treatments. Moreover, the band offsets are delicately correlated to the surface states, which plays a significant role in their photocatalytic performance. (paper)