Oxidation of Single-Walled Carbon Nanotubes under Controlled Chemical Conditions
Single-walled carbon nanotubes are oxidized in the presence of H2SO4/HNO3 mixtures containing distinct concentrations of the nitronium ion, [NO2+]. The spectroscopic analyses of the final samples suggest a higher structural disorder in the oxidized systems with increasing [NO2+]. This is due to a considerable oxygen amount on the tube surface, reaching up to 30%, depending on the reaction time and [NO2+]. Interestingly, if long reaction time is considered, the oxygen amount on the tube surface is maximum for low [NO2+] and reduces slightly for larger [NO2+]. On the other hand, the oxidation process occurs gradually at 4 h, allowing a fine control of the oxidation process. Therefore, if fine tuning of the oxidation degree is desirable, the reaction must be conducted during short time (4 h) using increasing [NO2+] as those obtained from 2:1, 2.5:1 and 3:1 H2SO4/HNO3 acid mixtures to produce increasing content of functionalization.
| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
2018
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532018001102387 |
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| Summary: | Single-walled carbon nanotubes are oxidized in the presence of H2SO4/HNO3 mixtures containing distinct concentrations of the nitronium ion, [NO2+]. The spectroscopic analyses of the final samples suggest a higher structural disorder in the oxidized systems with increasing [NO2+]. This is due to a considerable oxygen amount on the tube surface, reaching up to 30%, depending on the reaction time and [NO2+]. Interestingly, if long reaction time is considered, the oxygen amount on the tube surface is maximum for low [NO2+] and reduces slightly for larger [NO2+]. On the other hand, the oxidation process occurs gradually at 4 h, allowing a fine control of the oxidation process. Therefore, if fine tuning of the oxidation degree is desirable, the reaction must be conducted during short time (4 h) using increasing [NO2+] as those obtained from 2:1, 2.5:1 and 3:1 H2SO4/HNO3 acid mixtures to produce increasing content of functionalization. |
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