Carbon nanocapsules encapsulating cobalt nanoparticles by pulsed discharge plasma chemical vapor deposition

Silicon coated with a thin film of cobalt [Si/Co (10 nm)] is exposed to the plasma generated using CH4-H-2 gas mixture by making a discharge between Si/Co substrates and Mo bent plate in pulsed discharge plasma chemical vapor deposition. At high plasma temperature and deposition pressure, carbon nanocapsules encapsulating Co nanoparticles are observed to form. They are investigated using high resolution transmission electron microscopy, scanning electron microscopy, visible Raman spectroscopy and X-ray diffraction. Present study indicates that the formation mechanism of carbon nanocapsules lie in the sputtering of Co thin film by the energetic ions from plasma at high deposition pressure which results in the formation of Co nanoparticles, on surface of which graphitic layers gets deposited at high plasma temperature. Present approach provides a novel strategy for the synthesis of high purity carbon nanocapsules encapsulating metal nanoparticles. (C) 2007 Elsevier B.V. All rights reserved.