Plasma etching for purification and controlled opening of aligned carbon nanotubes

Plasma etching was applied for removal of the amorphous carbon layer that covers aligned carbon nanotube films produced by pyrolysis of metal-containing organometallic precursors. Microscopic and kinetic studies showed that amorphous carbon could be easily removed by H2O-plasma etching while carbon nanotubes remain largely unchanged under relatively mild plasma conditions. Prolonged plasma treatment, however, was found to cause a controllable disintegration of the graphitic structure, leading to a region-selective opening of the aligned carbon nanotubes (e.g., the removal of one end-cap only). Metal-filling was demonstrated to be also possible even with the resultant one-end opened nanotubes.