Preparation of double-walled carbon nanotubes using lanthanum as promoter

Double-walled carbon nanotubes (DWNTs) were prepared from graphite by arc discharge technique with La as promoter. The DWNTs products were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray diffraction and Raman spectroscopy. The results demonstrated that La was a suitable promoter reagent for making high purity DWNTs with narrow diameter distribution by arc discharge method. The role of La in the growth of the DWNTs was briefly discussed in terms of the relationship with metal catalysts.