Theoretical design of sandwich two-dimensional structures for photocatalysts and nano-optoelectronic devices

In this paper, three series of heterostructures of 2D transition metal dichalcogenides (including MoS2, MoSe2, MoTe2, WS2, WSe2, and WTe2) sandwiched by graphene (Gr), h-BN, and g-C3N4, which will be referred to as Gr sandwich heterostructures (SHS), h-BN-SHS, and g-C3N4-SHS in the rest of this paper, have been systematically studied firstly by using first-principle calculations. Gr-SHS are found to hold stable structures with an expanded band gap when MoSe2 and WSe2 are used as interlayers, indicating potential applications to Hall switch sensors. With the same type of interlayers, the stable h-BN-SHS shows additionally good response to visible light. In addition to good response to the visible light, effective electron-hole separation is also observed in g-C3N4-SHS. Such properties suggest structures in this sandwich type may be applied in plentiful areas, such as photocatalyst and solar cells. Moreover, the number and density of catalytically active sites in SHS may be dramatically increased. Consequently, we hope our findings could provide guidance for both the design of advanced materials and the corresponding nano-devices.