Nearly monodispersed carbon coated iron nanoparticles for the catalytic growth of nanotubes/nanofibres

We present the single step preparation of nano-iron cores embedded in carbon layers and their preliminary application to the growth of carbon nanotubes. CO2 laser pyrolysis of volatile iron and carbon precursors in a gas flow reactor was used in order to obtain the Fe-C nanocomposites. The structure and composition of the obtained nanopowders were analysed by transmission electron microscopy, high-resolution transmission electron microscopy, electron energy loss spectroscopy and Raman spectroscopy. The results indicate that the synthesized carbon embedded iron nanoparticles (similar to3-7 nm mean diameter) present sharp particle distributions. The degree of agglomeration and the number of surrounding carbon layers depend on the relative concentration of reactive donors. Silicon substrates seeded with a dilution of Fe-C nanocomposites were further used to catalyze nanotubes/nanofibres growth by the laser-induced CVD method. A deeper insight in the inception and growth mechanism of these structures is needed in order to achieve different levels of encapsulation and subsequent nanotube growth. (C) 2004 Elsevier B.V. All rights reserved.