Transition-metal-catalyzed unzipping of single-walled carbon nanotubes into narrow graphene nanoribbons at low temperature.

Open, sesame! Graphene nanoribbons (GNRs) with smooth edges and controllable widths are crucial for graphene electronic and spintronic applications. High-quality narrow GNRs can be synthesized from single-walled carbon nanotubes at 200-300 °C using a Cu-atom catalyst, which dramatically reduces the energy barrier of unzipping from 3.11 to 1.16 eV.