▎ 摘　　要

Longitudinal unzipping of carbon nanotubes (CNTs) can create graphene nano-ribbons (GNRs) with predetermined width. Experiments have used thus far an oxidative-induced unzipping approach that produces residual oxygen impurities. Here, we employ results of first-principles calculations to demonstrate an alternative scenario of GNR formation. We show that hydrogen loading at open CNT ends leads to successive C-C bond breaking and opening of CNTs to GNRs with edge morphologies that depend on CNT chirality. We also show that re-zipping of partially open CNTs can lead to new type of materials, for example, CNTs with lines of oxygen inter-carbon bridges. (C) 2011 American Institute of Physics. [doi:10.1063/1.3648105]