Interfaces between MoOx and MoX2 (X = S, Se, and Te)*

In the past decades there have been many breakthroughs in low-dimensional materials, especially in two-dimensional (2D) atomically thin crystals like graphene. As structural analogues of graphene but with a sizeable band gap, monolayers of atomically thin transition metal dichalcogenides (with formula of MX2, M = Mo, W; X = S, Se, Te, etc.) have emerged as the ideal 2D prototypes for exploring fundamentals in physics such as valleytronics due to the quantum confinement effects, and for engineering a wide range of nanoelectronic, optoelectronic, and photocatalytic applications. Transition metal trioxides as promising materials with low evaporation temperature, high work function, and inertness to air have been widely used in the fabrication and modification of MX2. In this review, we reported the fabrications of one-dimensional MoS2 wrapped MoO2 single crystals with varied crystal direction via atmospheric pressure chemical vapor deposition method and of 2D MoOx covered MoX2 by means of exposing MoX2 to ultraviolet ozone. The prototype devices show good performances. The approaches are common to other transition metal dichalcogenides and transition metal oxides.