Novel composite of Co/carbon nanotubes: Synthesis, magnetism and microwave absorption properties

Composites of flowery hexagonal close-packed (hcp) cobalt crystallite covered with multi-wall carbon nanotubes (MWCNTs) were fabricated in high yield via a simple catalytic pyrolysis method. A series of characterizations including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) revealed that MWCNTs grew on the surface of the cobalt flowers, which possibly followed a bottom-growth model. Thus-prepared Co/CNT composites not only exhibited much higher coercivity (772 Oe) than that of the initial pure cobalt flowers (308 Oe), but also showed much-enhanced microwave absorption than that of pure Co flowers or CNTs. The enhancement mechanism was investigated on the basis of the magnetic properties of Co/CNT composite and electromagnetic theory. (c) 2007 Elsevier Masson SAS. All rights reserved.