Chemical Vapor Deposition Based Synthesis of Carbon Nanotubes and Nanofibers Using a Template Method

TLDR

A new method for producing graphitic carbon nanofibers and nanotubes was developed. Carbon was synthesized by CVD inside alumina template pores using ethylene or pyrene at 545 °C with a Ni catalyst or at 900 °C without. The CVD process produced uniform hollow tubes that, with longer deposition, became nanofibers; post‑annealing at 500 °C for 36 h yielded highly ordered single‑crystal graphite nanofibers with planes aligned along the fiber axis.

Abstract

We have developed a new approach for preparing graphitic carbon nanofiber and nanotube ensembles. This approach entails chemical vapor deposition (CVD) based synthesis of carbon within the pores of an alumina template membrane with or without a Ni catalyst. Ethylene or pyrene was used in the CVD process with reactor temperatures of 545 °C for Ni-catalyzed CVD and 900 °C for the uncatalyzed process. The resultant carbon nanostructures were uniform hollow tubes with open ends. Increasing the deposition time converted the carbon nanotubes into carbon nanofibers. Transmission electron microscopy and electron diffraction data show the as deposited graphitic carbon nanofibers synthesized with the Ni catalyst were not highly ordered. Heating the carbon-containing membrane at 500 °C for 36 h, however, converts the carbon nanofibers into highly ordered graphite. The electron diffraction data show a spotted diffraction pattern characteristic of single-crystal graphite with the graphitic planes parallel to the long axis of the nanofibers.