The effects of pre-treatment and catalyst composition on growth of carbon nanofibers at low temperature

Carbon nanofiber films have been grown on Fe-Ni alloy catalysts at 400 degreesC by a thermal chemical vapor deposition (CVD) method using acetylene as a carbon source. Fe-Ni-C alloy catalysts were found to be more suitable for carbon nanofiber growth at 400 degreesC than pure Ni or Fe-Ni catalysts. When Fe-Ni catalysts were pre-treated in hydrogen at a low temperature (400 degreesC), the catalyst lost its activity in growing carbon nanofibers at 400 degreesC by forming an amorphous carbon layer covering catalytic sites on the surface. The growth rate of carbon nanofibers was improved significantly by pre-treating the catalyst with a low concentration of carbon source (e.g. acetylene, carbon monoxide) forming Fe-Ni-C alloy during the temperature-rising step before growth. Carbon nanofiber walls consisted of imperfect graphite structure as characterized by transmission electron microscopy. (C) 2001 Elsevier Science B.V. All rights reserved.