Probing plasma-induced defect formation and oxidation in carbon nanotubes by Raman dispersion spectroscopy

Lee, Szetsen; Peng, Jr-Wei; Liu, Chih-Hung

doi:10.1016/j.carbon.2009.08.019

Cited by 47 publications

(43 citation statements)

References 57 publications

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“…Furthermore, OD production is related to graphitic sheet cutting and unzipping processes induced by chemical oxidation with inorganic acids 31,44,48 . Both cutting and unzipping processes can be minimized in the oxidation through plasma treatment, thus preserving the integrity of nanotube morphology [49][50][51][52] . As the generation of OD is suppressed during oxidation through plasma treatment in oxygen-based blend gases, samples p-SWCNT and p-MWCNT did not have substantial amount of these byproducts.…”

Section: Nanocarbons Morphological and Structural Characterization Tmentioning

confidence: 99%

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Padovani¹,

Petry²,

Holanda³

et al. 2015

J. Phys. Chem. C

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There are successful protocols for dispersing carbon nanotubes and graphene oxide in physiological media by using biocompatible polymers, which enable their use in nanomedicine. However, there is not a clear understanding regarding the mechanisms of the colloidal stabilization manifested (i.e., electric, steric or electrosteric or through depletion forces). Here we show that the manifestation of a particular mechanism of stabilization for oxidized carbon nanotubes (CNTs) and graphene oxide (GO) in the presence of Pluronic F-127 (PF127) and short-and long-chain polyethylene glycol (PEG 1,500 or 35,000 respectively) depends on a proper matching between the nanocarbon morphology and the polymer chain length, chemical structure and concentration. The high aspect ratio one dimensional morphology of CNTs enables an initial steric and electrosteric stabilization through the nanotube wrapping (i.e., adsorption) by PF127 present in low concentrations (<0.1%). Depletion stabilization for CNTs manifests when PF127 is present in high concentrations (≥1.0%), thus enabling the formation of highly stable CNT colloids even in a 0.9% NaCl saline solution. This depletion stabilization depends little on the CNT structure (i.e., single-or multi-wall), surface charge (i.e., zeta potential), oxidation and carboxylation degree or the nanotube length. On the other hand, large-sized sheets of GO could be colloidally stabilized in NaCl 0.9% only in the presence of PEG 35,000 through repulsive depletion forces, whose manifestation occurs with a polymer concentration threshold of 5.0 wt%. Comparatively, in a physiological saline solution, PF127 is able to colloidally stabilize CNTs to a much large extent than PEG 35,000 stabilizes the large GO sheets.

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Section: Nanocarbons Morphological and Structural Characterization Tmentioning

confidence: 99%

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Padovani¹,

Petry²,

Holanda³

et al. 2015

J. Phys. Chem. C

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“…[5] In MWCNTs, the D band further appears (around 1610 cm −1 at 2.41 eV) as a weak shoulder to the G band. Similar to the D band, the D band is a disorder-activated double-resonance Raman feature; [13,14] the former is associated with the inter-valley scattering processes, while the latter originates from the intravalley processes. [13,14] The second-order spectrum of graphite (region above 2200 cm −1 of spectrum (a) in Fig.…”

Section: Raman Scattering In Graphite and Graphiterelated Carbonsmentioning

confidence: 99%

Evaluation of crystalline perfection degree of multi‐walled carbon nanotubes: correlations between thermal kinetic analysis and micro‐Raman spectroscopy

Santangelo

Messina

Faggio

et al. 2010

J Raman Spectroscopy

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Commercially available and laboratory-prepared multi-walled carbon nanotubes (MWCNTs) are systematically investigated by the use of micro-Raman spectroscopy (MRS), thermogravimetric analysis (TGA) and complementary techniques (scanning electron microscopy (SEM) and transmission electron microscopy (TEM)) with the aim of establishing a standardised postgrowth diagnostic protocol for the assessment of their overall crystalline quality. By studying a set of 'reference' samples, clear correlations are evidenced between the Raman graphitisation indexes (D/G, G /G and G /D intensity ratios) commonly adopted to describe the crystalline arrangement of nanotubes, and their reactivity towards oxygen, as measured by the apparent activation energy needed for their oxidation, inferred from the kinetic analysis in quasi-isothermal conditions. The higher the crystalline perfection degree, the higher the energy needed for oxidising them. The efficacy of the found correlations in indirectly assessing the reactivity of nanotubes prepared under different conditions is successfully demonstrated by the use of a second set of samples. The physical meaning and range of validity of the shown correlations are further discussed. Copyright

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“…2(e) quantitatively shows that the apparent contact angle of FMWCNT interfaces decreased with increasing plasma treatment time at a given oxygen flow rate. Raman analysis showed that more defects were introduced by longer plasma treatment time, 30 e.g., with more C¼O, OAC¼O and OAH groups, 23 which were indicated by an increasing I D /I G ratio 30 (refer to the supplement information). To better understand the effects of plasma treatment on the wetting property of CNTs, the change of static contact angle on pristine MWCNTs coatings without Nafion was studied.…”

mentioning

confidence: 99%

Enhanced nucleate boiling on horizontal hydrophobic-hydrophilic carbon nanotube coatings

Dai

Huang

Yang

et al. 2013

Applied Physics Letters

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Ideal hydrophobic-hydrophilic composite cavities are highly desired to enhance nucleate boiling. However, it is challenging and costly to fabricate these types of cavities by conventional micro/nano fabrication techniques. In this study, a type of hydrophobic-hydrophilic composite interfaces were synthesized from functionalized multiwall carbon nanotubes by introducing hydrophilic functional groups on the pristine multiwall carbon nanotubes. This type of carbon nanotube enabled hydrophobic-hydrophilic composite interfaces were systematically characterized. Ideal cavities created by the interfaces were experimentally demonstrated to be the primary reason to substantially enhance nucleate boiling.

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Probing plasma-induced defect formation and oxidation in carbon nanotubes by Raman dispersion spectroscopy

Cited by 47 publications

References 57 publications

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Evaluation of crystalline perfection degree of multi‐walled carbon nanotubes: correlations between thermal kinetic analysis and micro‐Raman spectroscopy

Enhanced nucleate boiling on horizontal hydrophobic-hydrophilic carbon nanotube coatings

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