Unravelling the Role of Topological Defects on Catalytic Unzipping of Single-Walled Carbon Nanotubes by Single Transition Metal Atom

Catalytic unzipping of single-walled carbon nanotubes (SWCNTs) has been experimentally shown to be a viable method to produce graphene nanoribbons (GNRs) with clean and smooth edges for advanced applications, while topological defects (TDs) are inevitably presented in mass produced CNTs (especially the tube end/cap), which may affect the catalytic unzipping. Herein, we theoretically investigate the roles of TDs on the catalytic unzipping of SWCNTs by a single Fe atom in the H ₂ environment. Our computation shows that the threshold reaction barriers to the catalytic SWCNT unzipping can be notably reduced by â=20%-40%, resulting from weakened and elongated local C-C bonds associated with TDs. The curvature energy of a SWCNT released during the unzipping can support the continuous unzipping and enable the chirality-and diameter-dependent unzipping. The important roles of H ₂ are also identified. The suggested tear-from-end-defect mechanism can markedly improve the controllability of the catalytic unzipping of SWCNTs.