Closed-Edged Graphene Nanoribbons from Large-Diameter Collapsed Nanotubes

The diameter dependence of the collapse of single- and double-walled carbon nanotubes to two- and four-walled graphene nanoribbons with closed edges (CE_<i>x</i>GNRs) has been experimentally determined and compared to theory. TEM and AFM were used to characterize nanotubes grown from preformed 4.0 nm diameter aluminum–iron oxide particles. Experimental data indicate that the energy equivalence point (the diameter at which the energy of a round and fully collapsed nanotube is the same) is 2.6 and 4.0 nm for single- and double-walled carbon nanotubes, respectively. Molecular dynamics simulations predict similar energy equivalence diameters with the use of ε = 54 meV/pair to calculate the carbon–carbon van der Waals interaction