Zipping and unzipping of nanoscale carbon structures

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 linear and nonhydrogenated zigzag or armchair edges have a 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, a line of sp(2) carbon bonds (common for pure carbon structures such as graphene or a carbon nanotube) converted into 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 for how to preserve the original structure, which is a crucial issue for their application in carbon-based electronics.