Formation of single-walled carbon nanotube via the interaction of graphene nanoribbons : ab initio density functional calculations

Recently, single graphite layers, referred to as Graphene nanoribbons (GNR) have been prepared experimentally by using conventional methods, such as cutting mechanically exfoloiated graphenes or by patterning epitaxially grown graphenes [1-2]. On the other hand, SWCNTs are typically grown as mixtures of metallic and semiconducting tubes and separating them has become a central issue in terms of effective fabrication of high performance electronic devices [3-4]. In this work, the interaction of bare graphene nanoribbons (GNRs) was investigated by ab initio density functional theory calculations with both the local density approximation (LDA) and the generalized gradient approximation (GGA). Remarkably, two bare 8-GNRs with zigzag shaped edges are predicted to form an (8, 8) armchair single-wall carbon nanotube (SWCNT) without any obvious activation barrier. The formation of a (10, 0) zigzag SWCNT from two bare 10-GNRs with armchair shaped edges has an activation barrier of 0.23 eV and 0.61 eV for using the LDA and the revised PBE exchange correlation functional, respectively. Our results suggest a possible route to control the growth of specific types SWCNT via the interaction of GNRs.