Method of purifying nanotubes and nanofibers using electromagnetic radiation
First Claim
1. A process for purifying a nanostructure mixture, said mixture comprisinga nanotube or a nanofiber, and a particle of a catalyst residue, said process comprising the steps of:
- inducing localized heating of said particle by exposing the mixture to electromagnetic radiation or an electromagnetic field; and
removing the particle from the mixture.
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Accused Products
Abstract
Disclosed are methods of purifying mixtures comprising nanofibers and/or nanotubes and residual catalyst particles that are covered by outer layers of the nanotube or nanofiber material. The mixtures are exposed to electromagnetic radiation, which induces localized heating in the residual catalyst particles. The localized heating creates breaches in the outer layers. Thereafter, the residual catalyst particles may be removed under relatively mild conditions that do not significantly affect the structural integrity of the nanotubes or nanofibers. The methods of the invention have been used to particular advantage in the purification of single wall carbon nanotubes (SWNTs) synthesized using metal catalysts. For these SWNTs, microwave radiation is preferably used to induce the localized heating, the outer layers are preferably removed at least in part by carrying out the localized heating under air, and the residual catalyst may be removed by exposure to relatively dilute aqueous acid.
132 Citations
35 Claims
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1. A process for purifying a nanostructure mixture, said mixture comprising
a nanotube or a nanofiber, and a particle of a catalyst residue, said process comprising the steps of: -
inducing localized heating of said particle by exposing the mixture to electromagnetic radiation or an electromagnetic field; and removing the particle from the mixture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A process for purifying a nanostructure, comprising the steps of:
synthesizing a nanofiber by a synthesis process, said synthesis process yielding the nanofiber and particles of a residue of a material promoting formation of said nanofiber, each of said particles being surrounded completely or incompletely by an outer layer of a composition similar to the composition of the nanofiber;
locally heating the outer layers; and
removing the particles.
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23. A process for purifying carbon nanotubes, comprising the steps of:
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providing a mixture comprising the carbon nanotubes and particles of a catalyst residue, each of said particles being at least partially surrounded by an outer layer, said outer layer comprising graphene carbon; exposing the particles to electromagnetic radiation or an electromagnetic field; and
removing the particles. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification