Synthesis and purification of single-walled carbon nanotubes in the cottonlike soot

The cottonlike soot with single-walled carbon nanotubes (SWNTs) is synthesized in large quantity under an improved arc discharge condition. It is found that the soot obtained under this condition contains much fewer multi-shell graphite particles compared to the clothlike soot produced earlier by our group and is much easier to be purified. High-purity SWNTs were obtained by combining oxidation in air and microwave-assisted acid treatment without multi-step filtration. SWNT purity was evaluated by SEM, TEM, thermogravimetric analysis, and Raman spectroscopy. Furthermore, the formation mechanism of the cottonlike soot is also discussed.