Low Temperature Growth of Carbon Nanotubes with Aligned Multiwalls by Microwave Plasma-CVD

Multiwall carbon nanotubes (MW-CNTs) have been prepared in a microwave-plasma enhanced CVD (MW-PECVD) tubular system at a low temperature similar to 300 degrees C from CH4-H-2 plasma with the addition of CO2 using as a week oxidant to selectively remove the amorphous carbon component and promote the CNT growth. CNTs are typically with outer diameter similar to 20 nm, inner diameter similar to 10 nm of several mu m in length and are grown via the tip growth process, bearing Fe catalyst nano-particles at the tip. The presence of CO2 as a weak oxidant in the plasma may influence in reducing the size of the support catalyst nano-particles and narrowing the CNTs with aligned multiwalls.