Rapid acid-mediated purification of single-walled carbon nanotubes with homogenization of bulk properties.

A rapid, mild and readily scaleable method for purification and isolation of single-walled nanotubes (SWNTs) using aqueous nitric acid that, in only 1-2 hours at reflux temperature, not only decrease the content of residual metal particles but also the relative ratio of small diameter and metallic NTs. The acid-treated SWNTs have been characterised by TEM, FT-IR, and Raman spectroscopy (514 and 783 cm-1). The results are discussed in relation to observations from other acid-mediated treatments and the reactive chemical species involved at different conditions.