Vapor-Phase Epitaxial Re-Growth Of Large Diameter Single-Walled Carbon Nanotubes

Long single-wall carbon nanotubes (SWCNTs) with a controlled conductivity type or chirality are interesting for fundamental study and are promising in many different technological applications, such as nanoelectronics, optoelectronics, and also upon utilizing them as nanoscale reactors to produce nanomaterials. In this study, the long aligned large diameter SWCNTs and the large diameter nanotube dense networks were synthesized via a vapor-phase epitaxial re-growth method. The nanotubes were re-grown on ST (stable temperature)-cut quartz substrates from short SWCNT seeds using the mixture of ethanol and acetylene as a precursor. The efficient nanotube re-growth was achieved using unsorted SWCNTs with diameters of 1.2-2.0nm and semiconducting SWCNTs, sorted by an aqueous two-phase extraction method, as seeds. According to our study, the re-grown nanotubes in an array have an average length of 5.5 mu m, while the individual re-grown nanotubes can reach up to 20-30 mu m. The extensive optical study confirms the preservation of SWCNTs diameter during the re-growth and signifies the high quality of produced nanotubes. We demonstrate the SWCNT chirality selective efficiency of the re-growth, which leads to predominance of the metallic nanotubes.