Effect of ferrocene concentration on the synthesis of bamboo-shaped carbon-nitrogen nanotube bundles.

We have investigated the effect of ferrocene concentration on the synthesis of carbon-nitrogen (C-N) nanotubes. The bamboo-shaped carbon-nitrogen nanotubes were synthesized by spray pyrolysis of Fe(C5H5)2 and CH3CN solution using argon as a carrier gas at the optimum temperature of approximately 900 degrees C. The effect of ferrocene concentration on the length and concentration of nitrogen in nanotubes was studied. Micro-structural features of the nanotubes were monitored employing scanning and transmission electron microscopic techniques. SEM studies reveal that with decreasing ferrocene concentration from 25 mg ml(-1) to 5 mg ml(-1), the length of the nanotubes vary from 80 microm to 430 microm. A feasible growth model has been described and discussed. X-ray photoelectron spectroscopic studies have confirmed the formation of nitrogen-doped carbon nanotubes. These studies reveal that the nitrogen concentration in the nanotubes decreases with the increase of ferrocene concentration. The present synthesis route also provides means of producing carbon nanotubes with different concentrations of nitrogen.