Study the multiwalled nanotubes growth mechanism overFe/Ni/Al2O3 from acetylene source

Abstract

Multiwalled cacbon nanotubes (MWNTs) were synthesized by Thermal - Chemical Vapor Deposition (T-CVD) technique using Fe/Ni/Al₂O₃. Acetylene was used as the source of cacbon and Argon as the carrier gas. The pyrolysis of hydrocacbon was investigated in the range of 400 – 750^oC to find out the optimal temperature and the growth mechanism of MWNTs would be discussed. By comparing the degree of crystallization (or graphitic level) of synthesized MWNTs, it was observed that at 650⁰C, the tube diameter obtained about 10- 20 nm and reaching the highest crystallization level. MWNTs getting at 650^oC were then purified through two-step process: air oxidation and acid treatment. The results showed that purification process could produce high purity MWNTs (≈95%).