Long and oriented single-walled carbon nanotubes grown by ethanol chemical vapor deposition

We report the controlled chemical vapor deposition (CVD) growth of single-walled carbon nanotubes (SWNTs), using ethanol as the carbon feedstock and bimetallic CoMo-doped mesoporous silica (SBA16) as the catalyst. Ultralong (up to 4 mm) and horizontally aligned SWNTs can be grown directly on flat substrates or across slits (20-120mum apart), and the orientation of the nanotubes is always parallel to the gas flow direction. The control of the growth direction and length also enables us to fabricate parallel nanotube arrays or two-dimensional networks on flat surfaces. The growth of the carbon nanotubes is relatively fast-it is attributed to the high reactivity of ethanol and high activity of the CoMo/SBA16 catalyst-and no doubt contributes to increased length and orientation control. Unlike previous procedures that have been used to grow well-oriented nanotubes, neither a strong external electrical field nor a fast-heating technique is required in this ethanol CVD process. Moreover, the as-grown SWNTs have a relatively narrow size distribution of 0.8-1.8 nm, which is a result of the narrow size distribution of the CoMo nanoparticles embedded in the mesoporous SBA16 silica.