H2O2/UV layer-by-layer oxidation of multiwall carbon nanotubes: The 'onion effect' and the control of the degree of surface crystallinity and diameter
| Autor: | Mauricio Terrones, Olga Martin Cadiz, Aaron Morelos-Gomez, Morinobu Endo, Viviana Jehová González, Kazunori Fujisawa, Sofía M. Vega-Díaz, Juan Baselga Llido |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Layer by layer 02 engineering and technology General Chemistry Carbon nanotube 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Electron spectroscopy 0104 chemical sciences law.invention Crystallinity symbols.namesake X-ray photoelectron spectroscopy Chemical engineering Transmission electron microscopy law symbols General Materials Science 0210 nano-technology High-resolution transmission electron microscopy Raman spectroscopy |
| Zdroj: | Carbon. 139:1027-1034 |
| ISSN: | 0008-6223 |
| Popis: | Hydrogen peroxide (H2O2) is an alternative oxidant and green method for the purification and functionalization of carbon nanotubes (CNTs), which works more efficiently in combination with UV radiation. In this paper, we investigated and monitored the oxidation mechanism of ethanol-synthesized and standard multi-walled carbon nanotubes. Characterization was carried out by high-resolution transmission electron microscopy (HRTEM), X-ray photo electron spectroscopy (XPS), acid/base titrations, thermo-gravimetric analysis (TGA) and Raman spectroscopy. Interestingly, we found a close correlation between oxidation time and the nature of the nanotubes. For the first time, a unique cyclic peeling of layers within MWNTs, termed “onion effect” was found. In this process, the degree of crystallinity of the outer layers significantly changed for the different peeling stages. We explain the process and how the number of layers within nanotubes gradually decreases when reaching critical acid concentrations. This method now allows the synthesis of MWCNTs with specific numbers of walls, diameter and controlled degree of crystallinity that could be effectively used for applications in biology and composites. |
| Databáze: | OpenAIRE |
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