Chirality-controlled carbon nanotubes fabricated by self-assembly of graphene nanoribbons

We demonstrate by molecular dynamics simulations that carbon nanotubes can activate and guide on their surfaces the fabrication of single-walled carbon nanotubes by self-assembly of edge-unpassivated twisted graphene nanoribbons. Temperature is a governing factor, which mainly controls the self-assembly process. Three types of stable configurations exist due to the self-assembly of twisted graphene nanoribbons at constant temperatures, i.e., a helical structure, a self-assembled carbon nanotube, and a nearly straight graphene strip, on a basal carbon nanotube. Raising the temperature gradually, the helical structure can spontaneously switch to a single-walled carbon nanotube or a nearly straight graphene strip. The straight graphene strip can further turn into a self-assembled carbon nanotube through annealing technique. Furthermore, the chirality of the self-assembled carbon nanotube can be predicted by the width of the twisted graphene nanoribbon and the radius of the basal carbon nanotube. Our finding should be useful for the design of nanodevices with chirality-controlled nanotubes.