Separation and optical identification of semiconducting and metallic single‐walled carbon nanotubes

Abstract

In this work we demonstrate a large‐scale separation of arc single‐walled carbon nanotubes into semiconducting and metallic fractions by an aqueous two‐phase extraction technique. The identification of nanotube conductivity type and the estimation of content for both fractions have been based on UV–vis–NIR optical absorption and time‐resolved pump–probe data. The fraction containing up to 98% of semiconducting nanotubes has been obtained. Optimization of the separation technique for the one‐step formation of high‐purity fractions via either temperature control or regulation of polymer–surfactant concentrations in the mixture has been proposed. The fractions enriched with semiconducting nanotubes can be used for transistor and optoelectronics applications. The metallic fractions can be efficient for formation of electric bus lines. UV–vis–NIR absorbance spectrum of pure semiconducting fraction of arc‐SWCNTs with an average diameter of 1.4 nm and the photo of 30 ml of this suspension.

Aqueous two-polymer phase extraction of single-wall carbon nanotubes using surfactants

“…The easiest application of ATPE is for the separation of highly enriched semiconducting SWCNT populations from the parent dispersion. 16,30,31 In my lab this is performed by competing SC with SDS for the SWCNT surface in the ATPE system, most effectively while in the presence of an oxidizing compound such as sodium hypochlorite (NaClO). In the important report of Gui et al, 35 the authors showed that addition of a small quantity of such an oxidizing agent both vastly improved robustness of the semiconducting from metallic separation delity, by effectively setting the redox potential in the ATPE system rather than relying on the ambient level, and could also enable band gap selection, critically between true metallic armchair, (n,m ¼ n), SWCNTs and the k B T level bandgap semi-metallic SWCNTs.…”

A Comparative Study of Field Emission From Semiconducting and Metallic Single‐Walled Carbon Nanotube Planar Emitters

“…Purification of nanotubes from byproducts was performed by tip sonication in 2 wt.% water solution of sodium cholate for 4 h and ultracentrifugation at 22 400 g. The separation of metallic and semiconducting nanotubes was made using the ATPE technique. [16] For this purpose two polymers À polyethylene glycol (6 kDa) and dextran (70 kDa), and two types of surfactants À sodium dodecyl sulfate and sodium cholate in appropriate concentrations were used. It is worth noting that separation of SWCNTs with such a large average diameter by ATPE technique was demonstrated for the first time here.…”

“…It is worth noting that separation of SWCNTs with such a large average diameter by ATPE technique was demonstrated for the first time here. The purity of obtained semiconducting and metallic fractions was estimated to 98%, [16] according to optical absorbance spectra (Figure 1). After sorting, SWCNTs were purified from residual polymers and surfactants by adding sodium chloride and ethanol to the suspension and ultracentrifugated at 360 000 g for 15 min in order to deposit the nanotubes.…”

Optical Features of Vapor‐Phase Epitaxial Re‐Grown Long Semiconducting Single‐Walled Carbon Nanotubes

“…Much effort has been put into chirality selective chemical vapor deposition (CVD) synthesis of SWCNTs . Significant progress was achieved in developing various SWCNT sorting methods . However, controlling simultaneously chirality of produced nanotubes and morphology of nanotube assembly is still a challenging task.…”

“…[4][5][6][7][8][9][10][11] Significant progress was achieved in developing various SWCNT sorting methods. [12][13][14][15][16][17][18] However, controlling simultaneously chirality of produced nanotubes and morphology of nanotube assembly is still a challenging task. One of the ways to obtain the desired level of the SWCNT structure control is a vapor-phase epitaxial (VPE) growth method.…”