Interlocking Friction Governs the Mechanical Fracture of Bilayer MoS 2 .

A molybdenum disulfide (MoS ₂ ) layered system is a two-dimensional (2D) material, which is expected to provide the next generation of electronic devices together with graphene and other 2D materials. Due to its significance for future electronics applications, gaining a deep insight into the fundamental mechanisms upon MoS ₂ fracture is crucial to prevent mechanical failure toward reliable applications. Here, we report direct experimental observation and atomic modeling of the complex failure behaviors of bilayer MoS ₂ originating from highly variable interlayer frictions, elucidated with in situ transmission electron microscopy and large-scale reactive molecular dynamics simulations. Our results provide a systematic understanding of the effects that different stacking and loading conditions have on the failure mechanisms and crack-tip behaviors in the bilayer MoS ₂ systems. Our findings unveil essential properties in fracture of this 2D material and provide mechanistic insight into its mechanical failure.