Curved Graphene Nanoribbons: Structure and Dynamics of Carbon Nanobelts

TL;DR

This study uses molecular dynamics simulations to analyze the formation, stability, and dynamics of carbon nanobelts derived from graphene nanoribbons, revealing spontaneous formation mechanisms and structural behaviors.

Contribution

It provides new insights into the energetics and formation processes of carbon nanobelts, highlighting their spontaneous formation at low temperatures and potential synthetic routes.

Findings

CNBs formation is driven by elastic energy and van der Waals interactions.

Beyond a critical diameter, CNBs are more stable than planar graphene.

Shorter CNBs tend to form perfect scrolls, longer ones form complex conformations.

Abstract

Carbon nanoribbons (CNRs) are graphene (planar) structures with large aspect ratio. Carbon nanobelts (CNBs) are small graphene nanoribbons rolled up into spiral-like structures, i. e., carbon nanoscrolls (CNSs) with large aspect ratio. In this work we investigated the energetics and dynamical aspects of CNBs formed from rolling up CNRs. We have carried out molecular dynamics simulations using reactive empirical bond-order potentials. Our results show that similarly to CNSs, CNBs formation is dominated by two major energy contribution, the increase in the elastic energy due to the bending of the initial planar configuration (decreasing structural stability) and the energetic gain due to van der Waals interactions of the overlapping surface of the rolled layers (increasing structural stability). Beyond a critical diameter value these scrolled structures can be even more stable (in terms of energy) than their equivalent planar configurations. In contrast to CNSs that require energy assisted processes (sonication, chemical reactions, etc.) to be formed, CNBs can be spontaneously formed from low temperature driven processes. Long CNBs (length of $\sim$ 30.0 nm) tend to exhibit self-folded racket-like conformations with formation dynamics very similar to the one observed for long carbon nanotubes. Shorter CNBs will be more likely to form perfect scrolled structures. Possible synthetic routes to fabricate CNBs from graphene membranes are also addressed.