Self-tearing and self-peeling of folded graphene nanoribbons

TL;DR

This study uses atomistic simulations to understand the atomic-scale mechanisms behind the self-tearing and self-peeling of folded graphene nanoribbons, revealing the influence of thermal fluctuations, substrate interactions, and edge structures.

Contribution

It provides new insights into the atomic-scale factors affecting graphene nanoribbon tearing and peeling, complementing experimental observations.

Findings

Large thermal fluctuations hinder the process by promoting chemical reactions.

Stronger graphene-substrate attraction increases initial growth velocities.

Armchair crack-edges produce more uniform cuts than zigzag edges.

Abstract

A recent experimental study showed that an induced folded flap of graphene can spontaneously drive itself its tearing and peeling off a substrate, thus producing long, micrometer sized, regular trapezoidal-shaped folded graphene nanoribbons. As long as the size of the graphene flaps is above a threshold value, the 'tug of war' between the forces of adhesion of graphene-graphene and graphene-substrate, flexural strain of folded region and carbon-carbon (C-C) covalent bonds favor the self-tearing and self-peeling off process. As the detailed information regarding the atomic scale mechanism involved in the process remains not fully understood, we carried out atomistic reactive molecular dynamics simulations to address some features of the process. We show that large thermal fluctuations can prevent the process by increasing the probability of chemical reactions between carbon dangling bonds of adjacent graphene layers. The effects of the strength of attraction between graphene and the substrate on the ribbon growth velocities at the early stages of the phenomenon were also investigated. Structures with initial armchair crack-edges were observed to form more uniform cuts than those having initial zigzag ones. Our results are of importance to help set up new experiments on this phenomenon, especially with samples with nanoscale sized cuts.