Edge-closed graphene nanoribbons fabricated by spontaneous collapse of few-walled carbon nanotubes.

A simple method of fabricating graphene nanoribbons (GNRs) with closed edges by utilizing the spontaneous collapsing mechanism of few-walled carbon nanotubes (CNTs) is demonstrated. The diameter of the tube that can be used to fabricate GNRs should be larger than a critical value, which is 16.27, 24.41 and 39.15 Å for single-, double- and triple-walled CNTs, respectively. The geometry of fabricated multi-layered GNRs consists of two highly strained bulbs on the two edges and a flat region with an interlayer distance of 3.4 Å. Defects at the initial tube wall affect the collapsing speed and GNR configuration. The encapsulated molecules slow the collapsing speed, and may even hinder the collapse of the tube.