In one aspect, provided is a method for producing a semiconducting single-walled carbon nanotube dispersion. This method allows semiconducting single-walled carbon nanotubes to be separated from a single-walled carbon nanotube mixture containing semiconducting single-walled carbon nanotubes and metallic single-walled carbon nanotubes in an aqueous medium, and yet requires only an easily available separation agent and a simple operation.

One aspect of the present disclosure relates to a method for producing a semiconducting single-walled carbon nanotube dispersion. The method includes (A) preparing a single-walled carbon nanotube dispersion to be separated that contains single-walled carbon nanotubes composed of semiconducting single-walled carbon nanotubes and metallic single-walled carbon nanotubes, an aqueous medium, and a nonionic polymer containing a constitutional unit A derived from a monomer represented by the following formula (1), and (B) centrifuging the single-walled carbon nanotube dispersion to be separated and then collecting a supernatant containing the semiconducting single-walled carbon nanotubes from the centrifuged single-walled carbon nanotube dispersion. A content of the constitutional unit A in all constitutional units of the polymer is 2 mol % or more. The polymer is water soluble.

CH.sub.2═CR.sup.1—COO—(EO).sub.p(PO).sub.q—R.sup.2   (1)

A carbon nanotube composite is a carbon nanotube composite including one carbon nanotube and an amorphous carbon-containing layer that coats the carbon nanotube, the carbon nanotube having a D/G ratio of 0.1 or less, the D/G ratio being a ratio of a peak intensity of a D band to a peak intensity of a G band in Raman spectroscopic analysis with a wavelength of 532 nm, the carbon nanotube composite being fibrous and having a diameter of 0.1 μm or more and 50 μm or less.

Provided is a fibrous carbon nanostructure that has excellent dispersibility after surface modification treatment. The fibrous carbon nanostructure has an amount of localized electrons of 1.0×10.sup.17/g or more as determined by electron spin resonance measurement at a temperature of 10 K.

Provided is a fibrous carbon nanostructure that has excellent dispersibility after surface modification treatment. The fibrous carbon nanostructure has an amount of localized electrons of 1.0×10.sup.17/g or more as determined by electron spin resonance measurement at a temperature of 10 K.

An optoelectronic system can include a single walled carbon nanotube (SWNT) device. The SWNT can include a carrier-doping density with optical conditions that control trion formation that respond via optical, electrical, or magnetic stimuli. The carrier-doping density can include a hole-polaron or electron-polaron concentration.

An optoelectronic system can include a single walled carbon nanotube (SWNT) device. The SWNT can include a carrier-doping density with optical conditions that control trion formation that respond via optical, electrical, or magnetic stimuli. The carrier-doping density can include a hole-polaron or electron-polaron concentration.

A method for preparation of conductive polymer/carbon nanotube (CNT) composite nanofiltration (NF) membrane and the use thereof. This conductive polymer/CNT composite NF membrane is obtained by polymerizing conductive polymer into a CNT membrane and then in-situ cross-linking with glutaraldehyde under acidic condition. The synthetic method for the conductive polymer/CNT composite NF membrane is simple and has no need of expensive equipment. The prepared membrane has controllable membrane structure and possesses superior electrical conductivity and electrochemical stability. The membrane can couple with electrochemistry for electrically assisted filtration. With the electrical assistance, the membrane can achieve improved ion rejection performance while retaining high permeability by enhancement of membrane surface charge density, which alleviates the permeability-selectivity trade-off. Furthermore, the electrically assisted NF membrane filtration can also enhance the removal for small molecular organic pollutants.

A method for preparation of conductive polymer/carbon nanotube (CNT) composite nanofiltration (NF) membrane and the use thereof. This conductive polymer/CNT composite NF membrane is obtained by polymerizing conductive polymer into a CNT membrane and then in-situ cross-linking with glutaraldehyde under acidic condition. The synthetic method for the conductive polymer/CNT composite NF membrane is simple and has no need of expensive equipment. The prepared membrane has controllable membrane structure and possesses superior electrical conductivity and electrochemical stability. The membrane can couple with electrochemistry for electrically assisted filtration. With the electrical assistance, the membrane can achieve improved ion rejection performance while retaining high permeability by enhancement of membrane surface charge density, which alleviates the permeability-selectivity trade-off. Furthermore, the electrically assisted NF membrane filtration can also enhance the removal for small molecular organic pollutants.

The present disclosure provides a method for purifying nanostructured material comprising carbon nanotubes, metal impurities and amorphous carbon impurities. The method generally includes oxidizing the unpurified nanostructured material to remove the amorphous carbon and thereby exposing the metal impurities and subsequently contacting the nanostructured material with carbon monoxide to volatilize the metal impurities and thereby substantially remove them from the nanostructured material.

The present disclosure provides a method for purifying nanostructured material comprising carbon nanotubes, metal impurities and amorphous carbon impurities. The method generally includes oxidizing the unpurified nanostructured material to remove the amorphous carbon and thereby exposing the metal impurities and subsequently contacting the nanostructured material with carbon monoxide to volatilize the metal impurities and thereby substantially remove them from the nanostructured material.