Synthesis of multi-walled C nanotubes by Fe–Ni (70 wt.%) catalyzed chemical vapor deposition from pre-heated CH4

This study aims to investigate effect of pre-heating of pure CH4 on the growth of C nanotubes by chemical vapor deposition in the presence of Fe–Ni (70 wt.%) alloy catalyst. It was observed that un-preheated CH4 yielded no C formation at 1050–1150 K owing to its poor decomposition rate, contrary to the results of thermodynamic analysis. Whereas, pre-heating treatment of CH4 at 1200 K prior to the growth increased pyrolysis of the hydrocarbon which promoted synthesis of C nanotubes at 1050–1150 K, possibly due to enhanced formations of intermediate gaseous species. TEM study revealed that the morphologies of the products consist of multi-walled C nanotubes.