Purification of single-walled carbon nanotubes

Abstract

Abstract. We present a study of purification of single-walled carbon nanotubes (SWCNTs) using different oxidation temperatures and chemical treatments. We have developed a simple two annealing-steps procedure resulting in high nanotube purity with minimal sample loss. The process involves annealing the SWCNTs at 300 • C for 2 h with subsequent reflux in 6 M HCl at 130 • C, followed by further annealing at 350 • C for 1 h with reflux in 6 M HCl at 130 • C. The process results in effective removal of carbon impurities and metal particles which are associated with SWCNTs production. The process is less time consuming (complete in 4.5 h) than conventional acid purification methods which require over 5 h, and less destructive than conventional methods with a yield of 26%. SWCNT purity was assessed using Raman spectroscopy, thermogravimetry and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy.

Hierarchical carbon nanotube membrane with high packing density and tunable porous structure for high voltage supercapacitors

“…Considering MgO support doesn't contribute to the capacitance and the Fe-Mo metals have negative effect on the stability of supercapacitor [18], a multistep method was used here to remove these impurities [19][20][21][22][23]. Firstly, pristine CNTs were directly etched by the CO 2 (96% purity) at 200-900°C, in an instrument of thermogravimetric analysis (TGA, TA, 5°C/min) in situ, which is effective to remove amorphous carbon, to open the cap or sidewall of tubes [2], and, to probably destroy some carbon capsules outside the Fe-Mo nanoparticles [22].…”

A charge-driven molecular flip-flop

“…The two external pulling forces fall within the force range of some available experimental facilities [17]. For instance, in experiments, the two carbon atoms, C 1 and C 2 , can connect organic groups by covalent bonds [18,19]. Therefore, F y1 and F y2 can be realized by drawing the organic groups [20].…”

Dispersion and functionalization of single-walled carbon nanotubes (SWCNTS) for nanocomposite applications

“…Impurities within the products include approximately 35 w% residual catalyst (Ni, Y) and some amorphous carbon on the outer surfaces of the ropes. The single-walled carbon nanotubes were purified by a method described elsewhere in the text [26].…”

“…Raman spectra were obtained from the raw (r-SWCNTs), purified (p-SWCNTs) and functionalized (f-SWCNTs) nanotubes using an argon (Ar + ) laser excitation of 785 nm with a resolution of 2 cm −1 . The procedure for obtaining the purified SWCNT samples has been described in Reference [26].…”