Transport of fullerene molecules along graphene nanoribbons

We study the motion of C60 fullerene molecules (buckyballs) and short-length carbon nanotubes on graphene nanoribbons. We demonstrate that the nanoribbon edge creates an effective potential that keeps the carbon structures on the surface. We reveal that the character of the motion of C60 molecules depends on temperature: for low temperatures (T<150K) the main type of motion is sliding along the surface, but for higher temperatures the sliding is replaced by rocking and rolling. Modeling of the buckyball with an included metal ion, such as Fe@C60, demonstrates that this molecular complex undergoes a rolling motion along the nanoribbon with the constant velocity under the action of a constant electric field. The similar effect is observed in the presence of the heat gradient applied to the nanoribbon, but mobility of carbon structures in this case depends largely on their size and symmetry, such that larger and more asymmetric structures demonstrate much lower mobility. Our results suggest that both electorphoresis and thermophoresis can be employed to control the motion of carbon molecules and fullerenes and, for example, sort them by their size, shape, and possible inclusions.