Modeling Nanoribbon Peeling

TL;DR

This paper develops a theoretical model for the mechanical peeling of graphene nanoribbons, identifying universal transition regimes influenced by bending rigidity and adsorption energy, validated by experimental data.

Contribution

It introduces a universal, analytical model for nanoribbon peeling, capturing transition regimes and explaining experimental observations.

Findings

Peeling involves distinct regimes: initial prying, peeling with stretching, peeling with sliding, and liftoff.

In negligible substrate corrugation, the transition simplifies to a universal, sharp crossover.

The model matches experimental data on graphene nanoribbons on Au(111).

Abstract

The lifting, peeling and exfoliation of physisorbed ribbons (or flakes) of 2D material such as graphene off a solid surface are common and important manoeuvres in nanoscience. The feature that makes this case peculiar is the structural lubricity generally realized by stiff 2D material contacts. We model theoretically the mechanical peeling of a nanoribbon of graphene as realized by the tip-forced lifting of one of its extremes off a flat crystal surface. The evolution of shape, energy, local curvature and body advancement are ideally expected to follow a succession of regimes: (A) initial prying, (B) peeling with stretching but without sliding (stripping), (C) peeling with sliding, (D) liftoff. In the case where in addition the substrate surface corrugation is small or negligible, then (B) disappears, and we find that the (A)-(C) transition becomes universal, analytical and sharp, determined by the interplay between bending rigidity and adsorption energy. This general two-stage peeling transition is identified as a sharp crossover in published data of graphene nanoribbons pulled off an atomic-scale Au(111) substrate.