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Journal of Nanomaterials
Volume 2011 (2011), Article ID 320516, 9 pages
Research Article

Decoration of Carbon Nanotubes with CoO and Co Nanoparticles

1Institute of Materials Science, N.C.S.R. “Demokritos” Agia Paraskevi, 15310 Athens, Greece
2ICMP, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, 1015 Lausanne, Switzerland
3Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece
4Department of Physics, University of South Florida, Tampa, FL 33620, USA

Received 1 September 2010; Revised 15 December 2010; Accepted 27 January 2011

Academic Editor: Gaurav Mago

Copyright © 2011 M. Belesi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Multiwall carbon nanotubes (MWNTs) decorated with CoO nanocrystals were synthesized by in-situ thermal decomposition of Co(acac)2 in oleyl amine under reflux conditions open in the air. The CoO/MWNTs composite material can be easily converted to metallic Co/MWNTs through annealing under reducing atmosphere (4%   ) at without any significant sintering effect. The composite materials characterized by X-ray diffraction, transmission electron microscopy, and Nuclear Magnetic Resonance (NMR) spectroscopy. The structural and morphological characterization shows that the CoO has cubic face (fcc) and the particles deposited uniformly on the external surface of the carbon nanotubes. In the annealed materials, the NMR shows that the fcc and hcp metallic Co phases coexist with a significant percentage of stacking faults. The magnetic measurements indicated that the CoO/MWNTs composite is largely composed of CoO nanoparticles with uncompensated surface spins. The fluctuations of spins persist in partially reduced CoO grains as shown by nuclear spin-lattice relaxation measurements.