Hydrogenation-assisted unzipping of carbon nanotubes to realize graphene nano-sheets

Abstract

We report the hydrogenation-assisted unzipping of multiwall carbon nanotubes grown on silicon substrates. Carbon nanotubes are formed using hydrogen and acetylene or methane in a direct-current plasma enhanced chemical vapor deposition chamber at a temperature of 650 °C. By patterning the nickel prior to the growth of CNTs, desired patterns are feasible which can be used for unzipping purposes. The unrolling of CNTs is feasible using a mixture of hydrogen and oxygen plasma treatments at temperatures ranging from 200 to 600 °C and in the presence of plasma powers of around 0.3–0.7 watt cm⁻². By the extended exposure of CNTs to hydrogen plasma at low powers, an anomalous swelling of CNTs has been observed. We believe that the swelling of CNTs is due to the incorporation of H atoms into CNT structure. Scanning electron microscopy, transmission electron microscopy; atomic force microscopy, Raman Spectroscopy and X-ray diffraction analyses have been exploited to investigate the physical properties of the synthesized nano-structures.