Selective oxidation of carbon nanotubes into zigzag graphene nanoribbons

Fabrication of graphene nanoribbons of desired edge and width is a critical challenge for its practical applications. Our first-principles calculations and molecular dynamics simulations show that oxygen atoms are favorable to adsorb on the high curvature sidewalls of radially deformed armchair single-walled carbon nanotubes (SWNTs) and form unzipped C-O-C epoxy lines. With further oxidation, the unzipped epoxy lines are broken into carbonyl pairs and the armchair SWNTs transform into bilayer graphene nanoribbons of zigzag edges and approximately identical widths. Under the same radial deformation and oxidation, the formation of normal epoxy groups on the high curvature regions of zigzag SWNTs are more favorable because of different bond arrangement, and the zigzag carbon nanotubes could not be broken into zigzag graphene nanoribbons by the same procedure. This result provides a possible way to selectively produce bilayer graphene nanoribbons of controlled structure from carbon nanotubes by mechanical and chemical coupling actions.