Controllable synthesis of carbon nanotubes with ultrafine inner diameters in ethanol flame

Carbon nanotubes (CNTs) with ultrafine inner diameters have been synthesized successfully through a simple ethanol flame method. The samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy, scanning electron microscopy, and Raman spectrum. The inner diameter as well as the crystallinity of the CNTs can be influenced greatly by controlling experimental conditions. The mechanism for the formation of this kind of multi-walled carbon nanotubes (MWCNTs) was proposed.