Atomic-scale perspective of mechanical properties and fracture mechanisms of graphene/WS2/graphene heterostructure

Abstract

The heterostructures synthesized by vertically stacking two-dimensional (2D) materials exhibit appealing and sophisticated features and functions that are typically missing in single-layer 2D materials. In our present study, the chirality and temperature-dependent mechanical characteristics and fracture process of graphene/h-WS2/graphene (GWG) vertical heterostructure in both armchair and zigzag loading directions are investigated utilizing molecular dynamics (MD) simulations. Our findings reveal that vertically sandwiching h-WS2 between two graphene layers significantly improves the h-WS2 monolayer's mechanical characteristics (Young's modulus and ultimate stress). Young's moduli of the heterostructure are higher than that predicted by the rule of mixture (ROM), especially at high temperatures. This points out a significant enhancement of mechanical properties due to the vertical stacking and strong interlayer interaction of graphene and WS2 layers. Moreover, we have discovered that while armchair loading causes the fracture to begin in the graphene layers, zigzag loading causes the crack to begin in either the WS2 layer or the graphene layers. Finally, this study illustrates an intriguing and thorough characterization of the GWG vertical heterostructures' mechanical properties and fracture mechanisms, as well as their temperature dependence and directional anisotropy, allowing for efficient and versatile application of the material in a variety of fields.