Influence of catalyst thickness and temperature gradient on MWCNT growth and morphology in TCVD process

In this article the effect of catalyst thickness and reaction temperature on the formation of horizontal multi-wall carbon nanotube (MWCNT) was discussed to control product growth and morphology. MWCNTs were synthesized from methane by double-heater thermal catalytic vapor deposition method (TCVD) using a mixture of methanol and ammonia as active agents to promote the growth of nanotubes and nickel as a catalyst and are characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Results from SEM indicated that, the diameter and density of tubes increased with increasing the catalyst thickness, whereas the effect of reaction temperature was on the growth efficiency and purity of nanotubes and lifetime of the catalyst. The most favorable temperature for the highest growth efficiency and purity was around 900 °C. However the optimal catalyst thickness was around 4 nm.