Longitudinal Cutting of Pure and Doped Carbon Nanotubes to Form Graphitic Nanoribbons Using Metal Clusters as Nanoscalpels

We report the use of transition metal nanoparticles (Ni or Co) to longitudinally cut open multiwalled carbon nanotubes in order to create graphitic nanoribbons. The process consists of catalytic hydrogenation of carbon, in which the metal particles cut sp<sup>2</sup> hybridized carbon atoms along nanotubes that results in the liberation of hydrocarbon species. Observations reveal the presence of unzipped nanotubes that were cut by the nanoparticles. We also report the presence of partially open carbon nanotubes, which have been predicted to have novel magnetoresistance properties.<sup>1</sup> The nanoribbons produced are typically 15−40 nm wide and 100−500 nm long. This method offers an alternative approach for making graphene nanoribbons, compared to the chemical methods reported recently in the literature.