Zipping and unzipping of nanoscale carbon structures

TL;DR

This paper provides a theoretical analysis of how hydrogenation and annealing influence the structural transformations of nanoscale carbon structures, affecting their merging or disassembly, which is vital for their use in electronics.

Contribution

It introduces a theoretical framework explaining how chemical modifications control the merging and disassembly of nanoscale carbon structures.

Findings

Hydrogenation facilitates disassembly of carbon structures by converting bonds to sp^3.

Annealing and hydrogenation promote merging into larger flakes or nanotubes.

Energy changes up to 6.22 eV drive structural transformations.

Abstract

We demonstrate theoretically that hydrogenation and annealing applied to nanoscale carbon structures play a crucial role in determining the final shape of the system. In particular, graphene flakes characterized by the linear and non-hydrogenated zigzag or armchair edges have high propensity to merge into a bigger flake or a nanotube (the formation of a single carbon-carbon bond lowers the total energy of the system by up to 6.22 eV). Conversely, the line of the $sp^2$ carbon bonds (common for pure carbon structures such as graphene or a carbon nanotube) converted into the $sp^3$ type by hydrogenation shows an ability to disassemble the original structure by cutting it along the line of the modified bonds. These structural transformations provide us with an understanding of the behavior of mobile carbon structures in solution and a distinct scenario of how to preserve the original structure which would be a crucial issue for their application in carbon-based electronics.