Superlubricity-activated thinning of graphite flakes compressed by passivated crystalline silicon substrates for graphene exfoliation

Abstract

A special thinning phenomenon is observed through molecular dynamics, where compression of AB-stacked graphite flakes between two hydrogen-terminated silicon substrates leads to the exfoliation of graphene layers. We have used multiple molecular dynamics simulations to study how this thinning phenomenon is affected by parameters such as size, number of graphene layers, and the crystalline orientation of the substrate surface. It is shown that this thinning phenomenon occurs through the activation of an inter-layer superlubricity regime, caused by torque-induced spontaneous rotations of the layers which are initiated by in-plane shear modes of graphite during compression.