The present teachings provide, in part, methods of separating two-dimensional nanomaterials by atomic layer thickness. In certain embodiments, the present teachings provide methods of generating boron nitride nanomaterials having a controlled number of atomic layer(s).

A method of separating and extracting carbon nanotubes, the method includes introducing the carbon nanotubes into a two-phase system that includes a first component and a second component, the first component being different from the second component. The method includes introducing a chemical agent into the two-phase system, mixing the chemical agent and the carbon nanotubes in the two-phase system, removing the first component to extract a first portion of the carbon nanotubes contained in the first component after the mixing, replenishing the two-phase system with fresh first component, and extracting a second portion of the carbon nanotubes contained in the fresh first component. A bandgap of the carbon nanotubes in the first portion is different from the bandgap of the carbon nanotubes in the second portion.

In one aspect, methods of making semiconducting single-walled carbon nanotubes are described herein. In some implementations, a method of making semiconducting single-walled carbon nanotubes comprises providing a plurality of semiconducting nanotube seeds including (n,m) nanotube seeds and non-(n,m) nanotube seeds. The method further comprises illuminating the plurality of nanotube seeds with a first laser beam having a first wavelength and a second laser beam having a second wavelength, the second wavelength differing from the first wavelength. The first wavelength corresponds to an absorption maximum for a (n,m) carbon nanotube and the second wavelength corresponds to a photoluminescence emission frequency for the (n,m) carbon nanotube.

In one aspect, methods of making semiconducting single-walled carbon nanotubes are described herein. In some implementations, a method of making semiconducting single-walled carbon nanotubes comprises providing a plurality of semiconducting nanotube seeds including (n,m) nanotube seeds and non-(n,m) nanotube seeds. The method further comprises illuminating the plurality of nanotube seeds with a first laser beam having a first wavelength and a second laser beam having a second wavelength, the second wavelength differing from the first wavelength. The first wavelength corresponds to an absorption maximum for a (n,m) carbon nanotube and the second wavelength corresponds to a photoluminescence emission frequency for the (n,m) carbon nanotube.

The present disclosure provides methods for removing defects nanotube application solutions and providing low defect, highly uniform nanotube fabrics. In one aspect, a degassing process is performed on a suspension of nanotubes to remove air bubbles present in the solution. In another aspect, a continuous flow centrifugation (CFC) process is used to remove small scale defects from the solution. In another aspect, a depth filter is used to remove large scale defects from the solution. According to the present disclosure, these three methods can be used alone or combined to realize a low defect nanotube application solutions and fabrics.

Provided is a method for uniform dispersion of single-wall carbon nanotubes, comprising: (1) dispersing single-wall carbon nanotube powder in a low-boiling point alcohol or water or DMF, then placing into a UV bench for ultraviolet irradiation and oxidation; (2) after cleaning the carbon nanotubes in the UV bench, using a strong acid to carry out an oxidation reaction, then washing by centrifugation; (3) after cleaning with strong acid, subjecting the single-wall carbon nanotubes to ethanol or water ultrasonic dispersion 2-3 times, washing by centrifugation, then dissolving in low-boiling point alcohol or water or DMF solution to obtain a single-wall carbon nanotube dispersion. By means of the present method, the entire surface of a carbon nanotube is grafted with a functionalized group, achieving solubility of single-wall carbon nanotubes; further, high-performance carbon nanotube composite flexible transparent electrode materials can be prepared, which have high transmittance and low sheet resistance.

The present disclosure provides a nanotube solution being treated with a molecular additive, a nanotube film having enhanced adhesion property due to the treatment of the molecular additive, and methods for forming the nanotube solution and the nanotube film. The nanotube solution includes a liquid medium, nanotubes in the liquid medium, and a molecular additive in the liquid medium, wherein the molecular additive includes molecules that provide source elements for forming a group IV oxide within the nanotube solution. The molecular additive can introduce silicon (Si) and/or germanium (Ge) in the liquid medium, such that nominal silicon and/or germanium concentrations of the nanotube solution ranges from about 5 ppm to about 60 ppm.

In one aspect, methods of making semiconducting single-walled carbon nanotubes are described herein. In some implementations, a method of making semiconducting single-walled carbon nanotubes comprises providing a plurality of semiconducting nanotube seeds including (n,m) nanotube seeds and non-(n,m) nanotube seeds. The method further comprises illuminating the plurality of nanotube seeds with a first laser beam having a first wavelength and a second laser beam having a second wavelength, the second wavelength differing from the first wavelength. The first wavelength corresponds to an absorption maximum for a (n,m) carbon nanotube and the second wavelength corresponds to a photoluminescence emission frequency for the (n,m) carbon nanotube.

In various embodiments, a method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes may be provided. The method may include the steps of (a) passing a carbon nanotube dispersion over a charged material. The dispersion may include a mixture of the semiconducting carbon nanotubes and the metallic single-walled carbon nanotubes. The method may further include (b) passing an eluent solution through the charged material after (a). The method may also include (c) collecting an eluate including semiconducting carbon nanotubes or a mixture of semiconducting carbon nanotubes and metallic carbon nanotubes.

The present disclosure provides methods for removing defects nanotube application solutions and providing low defect, highly uniform nanotube fabrics. In one aspect, a degassing process is performed on a suspension of nanotubes to remove air bubbles present in the solution. In another aspect, a continuous flow centrifugation (CFC) process is used to remove small scale defects from the solution. In another aspect, a depth filter is used to remove large scale defects from the solution. According to the present disclosure, these three methods can be used alone or combined to realize a low defect nanotube application solutions and fabrics.