Nanotribological Properties of Graphene/h-BN Heterostructures

Heterogeneous two-dimensional (2-D) layered nanomaterials have recently gained significant interest due to their potential as lubricant additives and solid lubricants, aimed at enhancing the energy efficiency of tribological systems. For instance, 2-D heterogeneous layered interfaces, composed of graphene and hexagonal boron nitride (h-BN), have exhibited excellent superlubricity owing to their inherent lattice mismatch, weak interlayer van der Waals (vdW) interactions, and the presence of moiré patterns. However, a comprehensive understanding of the impact of temperature and structural defects on the nanotribological properties of these 2-D heterogeneous structures remains elusive. In this work, we employ molecular dynamics simulations to investigate how friction in a heterostructure system is influenced by temperature variations and the presence of structural defects. Our study employs a molecular dynamics model simulating a silicon tip sliding over a graphene/h-BN heterostructure, mimicking atomic force microscopy experiments. We systematically measured the coefficient of friction across various stack orderings of the graphene/h-BN heterostructure, at different normal loads and temperatures. Furthermore, we delve into the effects of Stone–Wales (SW) defects on the frictional properties of the graphene/h-BN heterostructure. We quantitatively assess the lateral force variations during the sliding process when SW defects are present on the topmost layer, drawing comparisons with defect-free heterostructure cases. These investigations shed light on the intricate interplay between temperature, structural defects, and frictional behavior in graphene/h-BN heterostructures, offering valuable insights for the development of advanced lubricants and tribological systems.