Facet-governed frictional behavior in graphene/h-BN heteronanotubes

Abstract

Superlubricity, a state characterized by ultra-low friction and nearly-zero wear, has conventionally been linked to planar incommensurate interfaces between heterogeneous van der Waals layered materials. In this work, our investigation introduces a novel perspective by highlighting the pivotal role of curvature in heterostructures. Employing our recently developed anisotropic interlayer force field, we demonstrate the profound impact of size and chirality on the morphological characteristics, specifically circumferential faceting, of heterogeneous graphene/h-BN nanotubes. This exploration unravels a consequential transition from a superlubric to a high-friction state, coinciding with the transformation of nanotube cross-sections from cylindrical to faceted shapes. The induction of a faceted scenario triggers redistribution of moiré-dependent distortion deformation during sliding, resulting in a transition from a stick-slip mode to a high-friction state. This stands in stark contrast to the smooth-sliding mode (superlubric state) observed in non-faceted heterogeneous nanotubes. Our discoveries provide valuable insights for the intentional design of quasi one-dimensional van der Waals metamaterials and devices with tunable tribological properties, and expand the current understanding of superlubricity.