Simplified synthesis of double-wall carbon nanotubes

We demonstrate a simplified synthesis technique for double-wall carbon nanotubes that is an adaptation of chemical vapor deposition (CVD) techniques used previously for the production of single-wall nanotubes. Double-wall nanotubes (DWNTs) provide ideal geometries for numerous fundamental structural, electronic, thermal and vibrational studies, as well as providing a unique new platform for practical applications. The diameter distribution of DWNTs is broad, and it is possible that in previous studies using CVD-grown small-diameter nanotubes, presumed to be single-wall, there were significant numbers of DWNTs present.