Oxidation of multiwalled carbon nanotubes by nitric acid

Rosca, I. D.; Watari, Fumio; Uo, Motohiro; Akasaka, Tsukasa

doi:10.1016/j.carbon.2005.06.019

Cited by 701 publications

(430 citation statements)

References 16 publications

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“…But low purity of the MWNTs and hydrophobic and inert nature of the surface of MWNTs reduce their applications. The oxidation of MWNTs by using wet chemical [1][2][3][4][5][6][7][8][9], photo oxidation [10][11][12][13], gas phase treatment [13], and oxygen plasma [10] method is a basic technique for purification and also improvement of the chemical reactivity of the MWNTs.…”

Section: Introductionmentioning

confidence: 99%

A study on the dependence of structure of multi-walled carbon nanotubes on acid treatment

et al. 2015

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In the current research, the role of both concentrated nitric acid and ultrasound waves on oxidation of multi-walled carbon nanotubes (MWNTs) was studied. The functionalized MWCNTs were characterized by transmission electron microscopy (TEM), thermogravimetric analyzer, and Fourier transform infrared spectroscopy (FTIR) techniques. It was found that desirable modifications to MWNTs occurred after acid treatment. Carboxylic acid groups were appeared on the side surfaces of MWNTs. FTIR presented the formation of oxygen-containing groups such as C=O and COOH after modification by concentrated nitric acid. The TEM images showed that the aspect ratio of opened MWCNTs was controlled by both ultrasonic waves and acid treatment time. It was also found that the exposure of about 4 h in nitric acid led to the highest removal of the impurities with the least destructive effect.

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Section: Introductionmentioning

confidence: 99%

A study on the dependence of structure of multi-walled carbon nanotubes on acid treatment

et al. 2015

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“…carboxylic groups) is by oxidation. Indeed, oxidation reactions in air 20 or nitric (HNO 3 ) 21 and sulfuric (H 2 SO 4 ) 22 acids create defective sites in the wall structure, resulting in the formation of carboxyl and carbonyl groups on the surface of the nanotubes. These groups can be used as sites for further functionalization by other molecules.…”

Section: Introductionmentioning

confidence: 99%

Monitoring oxidation of multiwalled carbon nanotubes by Raman spectroscopy

Osswald

Havel

Gogotsi

2007

J Raman Spectroscopy

546

362

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Multiwalled carbon nanotubes (MWCNTs) were oxidized in air and acids while varying the treatment time and/or temperature. The goal of this approach was to create the highest density of carboxyl groups with moderate sample loss, which is necessary for nanocomposite applications. In situ Raman experiments allowed real-time observation of the structural changes in MWCNTs upon oxidation. The ratio of the Raman intensities of the D and G bands was used to estimate the concentration of defects. It was found that while an oxidation for 6 h in H 2 SO 4 /HNO 3 provided the strongest effect, a 'flash oxidation' in air (15 min at 550°C) also leads to an efficient functionalization in a cost-effective and environmentally friendly way. Transmission electron microscopy, Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis and electrophoretic mobility analysis were used to study the oxidized nanotubes.

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“…For example, Liu et al [20] first reported the severe oxidative treatment of SWNT when using a reflux mixture of concentrated sulfuric and nitric acids (H 2 SO 4 /HNO 3 3:1, 98% and 40% respectively). Interestingly, variations of this method have been widely used by various researchers to purify (removal of catalyst impurities and amorphous carbon) and functionalize SWCNT and MWCNT [16,17,20,21,24]. González-Guerrero et al [25] found that the concentration of total acidic groups increased up to 2.5 Â 10 À5 mol mg À1 after 6 h of refluxing time, and remained constant at longer refluxing periods.…”

Section: Introductionmentioning

confidence: 99%

“…These authors indicate that various functional groups can be introduced to the tubes surfaces when the SWNTs are treated with different oxidizing agents. Dilute nitric acid has shown to generate carboxylic acid groups on defect sites already present within nanotubes, whereas a mixture of concentrated sulfuric and nitric acids generates carboxylic acid groups on newly created defective sites [23,24]. Potassium permanganate introduces different amounts of hydroxyl, carbonyl and carboxylic groups within the nanotubes surface [35].…”

Section: Introductionmentioning

confidence: 99%