Two-dimensional (2D) nano-materials, such as molybdenum disulfide (MoS2) and graphene, have atomic or molecular thickness, exhibiting promising applications in nano-electro-mechanical systems. Graphene is a one-atom thick carbon sheet, with atoms arranged in a regular hexagonal pattern. Molybdenum disulfide (MoS2) belongs to transition metal dichalcogenides (TMD) semiconductor family YX2 (Y=Mo, W; X=S, Se, Te), with a layered structure. This project aims to demonstrate novel opto-electronic devices, like light-emitting diode (LED), solar cells, etc. These 2D nano-materials can also be integrated into nano-electro-mechanical systems, enabling ultra-sensitive mechanical mass sensors, with single molecule or even single atom sensitivities. Moreover, the mechanical resonators based on these 2D nano-materials would be a perfect platform to investigate quantum mechanics, opto-mechanics, material internal friction force, nonlinear physics, etc.