Robust Superlubricity in Graphene/h-BN Heterojunctions

TL;DR

This study demonstrates that heterostructures of graphene and h-BN exhibit robust superlubricity due to reduced sliding energy barriers, especially in large flakes, making them promising for dry lubrication applications.

Contribution

It reveals that graphene/h-BN heterojunctions maintain low friction across misorientations, unlike homogeneous graphene, due to size-dependent energy landscape effects.

Findings

Sliding energy corrugation decreases with flake size.

Large flakes exhibit at least ten times lower energy barriers.

Heterogeneous interfaces are promising for dry lubrication.

Abstract

The sliding energy landscape of the heterogeneous graphene/h-BN interface is studied by means of the registry index. For a graphene flake sliding on top of h-BN the anisotropy of the sliding energy corrugation with respect to the misfit angle between the two naturally mismatched lattices is found to reduce with the flake size. For sufficiently large flakes the sliding energy corrugation is expected to be at least an order of magnitude lower than that obtained for matching lattices regardless of the relative interlayer orientation thus resulting in a stable low-friction state. This is in contrast to the case of the homogeneous graphene interface where flake reorientations are known to eliminate superlubricty. Our results mark heterogeneous layered interfaces as promising candidates for dry lubrication purposes.