On the purification of CVD grown boron doped single-walled carbon nanotubes

In this paper, we report a facile purification method of boron-doped single-walled carbon nanotubes (SWCNTs) produced by high vacuum chemical vapor deposition (HV-CVD). The raw material was doped in situ during growth, with a B content below 0.5 at.%, estimated by means of X-ray photoelectron spectroscopy (XPS). Using ultracentrifugation combined with a mild acid solution pH neutralization, we have proved it is feasible to purify this material, which originally contains synthesis byproducts that differ from the typical catalytic remaining in pristine carbon nanotube samples produced with a similar method. The diameter size and distribution previous and after purification have been monitored by multi-frequency Raman spectroscopy.