Tearing Graphene Sheets From Adhesive Substrates Produces Tapered Nanoribbons

TL;DR

This study combines simulations and experiments to investigate how graphene tears from substrates, revealing that the resulting nanoribbon shape depends on adhesion energy and layer count, providing insights into 2D material fracture mechanics.

Contribution

It introduces a combined computational and experimental approach to understand tearing mechanisms in graphene, highlighting the control of nanoribbon geometry by adhesion and layer number.

Findings

Tapered graphene nanoribbons are formed during tearing.

Nanoribbon geometry depends on adhesion energy and layer number.

Results offer fundamental insights into 2D material fracture mechanisms.

Abstract

Graphene is a truly two-dimensional atomic crystal with exceptional electronic and mechanical properties. Whereas conventional bulk and thin-film materials have been studied extensively, the key mechanical properties of graphene, such as tearing and cracking, remain unknown, partly due to its two-dimensional nature and ultimate single-atom-layer thickness, which result in the breakdown of conventional material models. By combining first-principles ReaxFF molecular dynamics and experimental studies, a bottom-up investigation of the tearing of graphene sheets from adhesive substrates is reported, including the observation of the formation of tapered graphene nanoribbons. Through a careful analysis of the underlying molecular rupture mechanisms, it is shown that the resulting nanoribbon geometry is controlled by both the graphene-substrate adhesion energy and by the number of torn graphene layers. By considering graphene as a model material for a broader class of two-dimensional atomic crystals, these results provide fundamental insights into the tearing and cracking mechanisms of highly confined nanomaterials.