Published online by Cambridge University Press: 01 February 2011
The alignment, orientation and morphologies of multi-walled carbon nanotubes (MWNTs) can be tailored by controlling catalyst deposition on porous silicon substrates. During the growth of MWNTs, H2 promoted the growth of carbon nanotubes and prevented the formation of amorphous carbon particles. With the introduction of H2, the average diameter of MWNTs decreased from 130 nm to 15 nm, and the average growth rate of nanotubes increased from 50 nm/s to 145 nm/s. The use of CH4 as the carbon source resulted in single-walled carbon nanotubes (SWNTs) with an average diameter of 2 nm, and the use of C2H2 as the carbon source resulted in MWNTs with an average diameter of 15 nm.