RESUMEN
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(2) 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.(1) 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.
Asunto(s)
Nanocompuestos/química , Nanotecnología/métodos , Nanotubos de Carbono/química , Catálisis , Cobalto/química , Diseño de Equipo , Grafito/química , Microscopía de Fuerza Atómica/métodos , Microscopía Electrónica de Rastreo/métodos , Microscopía Electrónica de Transmisión/métodos , Níquel/químicaRESUMEN
We present a class of intramolecular graphene heterojunctions and use first-principles density functional calculations to describe their electronic, magnetic, and transport properties. The hybrid graphene and hybrid graphene nanoribbons have both armchair and zigzag features that are separated by an interface made up of pentagonal and heptagonal carbon rings. Contrary to conventional graphene sheets, the computed electronic density of states indicates that all hybrid graphene and nanoribbon systems are metallic. Hybrid nanoribbons are found to exhibit a remarkable width-dependent magnetic behavior and behave as spin polarized conductors.
RESUMEN
We use first principles calculations to investigate the magnetic properties of zinc oxide nanoribbons with zigzag-terminated edges. The polarized spin density of states is calculated as a function of the nanoribbons width and thickness. All nanoribbons formed by a single layer exhibit a magnetic behavior independently of the width. By analyzing the charge density and spin density, we determine that the oxygen-dominated edge exhibits unpaired spins. When the thickness of the ribbons is increased, a magnetic moment is observed only for specific thicknesses.