Purification and Characterization of Single-Wall Carbon Nanotubes

Chiang, Ivana W.; Brinson, Bruce E.; Smalley, R. E.; Margrave, and J. L.; Hauge, Robert H.

doi:10.1021/jp003453z

Cited by 528 publications

(421 citation statements)

References 36 publications

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“…One efficient dry purification technique is oxygen burning, or annealing, in which oxygen gas preferentially oxidizes both amorphous carbon and sp 3 -hybridized carbon nanoparticles, which are more reactive than sp 2 -hybridized SWNTs. 41,42 Wet techniques such as liquid or size-exclusion chromatography 43,44 and high-speed centrifugation 45 provide limited SWNT separation from other forms of carbon. Still, the primary obstacle for nanotube purification is removal of residual metal catalyst particles that embed between the SWNTs; these particles are more stable than nanotubes and are therefore difficult to remove.…”

Section: Purification Of Swntsmentioning

confidence: 99%

“…27 Removal of the catalyst is usually accomplished with a nitric acid reflux, which also eradicates any remaining superfluous carbon. 41,[46][47][48] Although dry and wet purification methods remove the majority of residual carbon and metal catalysts, it is important to note that some residual impurities remain in all current SWNT samples.…”

Section: Purification Of Swntsmentioning

confidence: 99%

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Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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Section: Purification Of Swntsmentioning

confidence: 99%

Section: Purification Of Swntsmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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“…It should be noted that the burning temperature of the K 2 S 2 O 8 -treated CarboLex SWNTs sample increases in comparison with the starting materials. This is a result of partial removal of metal catalysts [11] as verified by the smaller amount of residue at 900 8C than that of the as-prepared SWNTs sample. In summary, K 2 S 2 O 8 oxidation plays roles in modifying, unbundling and coating SWNTs, along with partial removal of amorphous carbon and metal catalysts.…”

Section: Chemical Modifications Of Swntsmentioning

confidence: 82%

“…Since metal catalytic particles are always found encapsulated in PCNs, the accessibility of acids to them is a severe problem. It has been reported that exposure to moist air or wet Ar/O 2 mixture [11], ultrasonic suspension with inorganic nanoparticles [12], ozone oxidization [13], and microwave treatment [14,15] can breach the surrounding carbon shell to some degree. But, under these severe conditions further damage on the remaining walls of SWNTs inevitably took place.…”

Section: Introductionmentioning

confidence: 99%

Centrifugal purification of chemically modified single-walled carbon nanotubes

Jia

Lian

Ishitsuka

et al. 2005

Science and Technology of Advanced Materials

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A wet chemistry procedure which couples chemical functionalization and a dispersion-centrifugation cycle was applied to the dissolution and purification of as-prepared electric-arc produced single-walled carbon nanotubes (SWNTs). It is validated that K 2 S 2 O 8 treatment generates hydrophilic groups such as carboxyl and hydroxyl on the surfaces of varying carbons, whereas such treatment also causes no severe destruction on the structure of SWNTs. Amidation of the K 2 S 2 O 8 -treated and mixed acids shortened SWNTs leads them largely soluble in tetrahydrofuran (THF) or other organic solvents. The soluble sample was fractionated via a dispersion-centrifugation cycle and highly pure and well-separated SWNTs were successfully obtained in the middle fractions. The purity of the centrifugally fractionated samples is qualitatively estimated with Raman spectroscopy, scanning electron microscope (SEM), and atomic force microscopy (AFM). Quantitative optical absorption spectroscopy and thermogravimetric analysis show that about 60% nanotubes in the starting material are transferred into liquid phase and the carbonaceous purity reaches as high as 129% of a reference sample R2, an 'impurity-free' fragment of soot directly from the arc chamber. q

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“…N- As-prepared CNTs contain carbonaceous impurities, such as amorphous carbon and graphite nanoparticles, and particles of the transition-metal catalysts (see Note 2). The use of high-temperature oxidation in air is effective in removing amorphous and graphitic contaminants from MWCNTs; for SWCNTs, however, metal catalysts must first be removed before this oxidation step since such metals are known to catalyze the low-temperature oxidation of CNTs (12,13). In principle, the purification of SWCNTs is feasible by using a combination of the following: gas-or vaporphase oxidation; wet-chemical oxidation/treatment; and centrifugation or filtration (including chromatography techniques) (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”

Section: -Pyrenebutanoic Acid Succinimidyl Ester (Pase)mentioning

confidence: 99%

Purification, Functionalization, and Bioconjugation of Carbon Nanotubes

Luong

Male²,

Mahmoud³

et al. 2011

Methods in Molecular Biology

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Bioconjugation of carbon nanotubes (CNTs) with biomolecules promises exciting applications such as biosensing, nanobiocomposite formulation, design of drug vector systems, and probing protein interactions. Pristine CNTs, however, are virtually water-insoluble and difficult to evenly disperse in a liquid matrix. Therefore, it is necessary to attach molecules or functional groups to their sidewalls to enable bioconjugation. Both noncovalent and covalent procedures can be used to conjugate CNTs with a target biomolecule for a specific bioapplication. This chapter presents a few selected protocols that can be performed at any wet chemistry laboratory to purify and biofunctionalize CNTs. The preparation of CNTs modified with metallic nanoparticles, especially gold, is also described since biomolecules can bind and self-organize on the surfaces of such metal-decorated CNTs.

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Purification and Characterization of Single-Wall Carbon Nanotubes

Cited by 528 publications

References 36 publications

Photophysics of Individual Single-Walled Carbon Nanotubes

Photophysics of Individual Single-Walled Carbon Nanotubes

Centrifugal purification of chemically modified single-walled carbon nanotubes

Purification, Functionalization, and Bioconjugation of Carbon Nanotubes

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