TY - JOUR
T1 - H2O2/UV layer-by-layer oxidation of multiwall carbon nanotubes
T2 - The “onion effect” and the control of the degree of surface crystallinity and diameter
AU - González, Viviana Jehová
AU - Vega-Díaz, Sofía Magdalena
AU - Morelos-Gómez, Aarón
AU - Fujisawa, Kazunori
AU - Endo, Morinobu
AU - Cadiz, Olga Martin
AU - Llido, Juan Baselga
AU - Terrones, Mauricio
N1 - Funding Information:
Authors wish to acknowledge financial support from Spanish Ministerio de Economía y Competitividad under grant MAT2014-57557-R. MT thanks the Comunidad de Madrid and Banco Santander for the chair of excellence award.
Publisher Copyright:
© 2018
PY - 2018/11
Y1 - 2018/11
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85053132119&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85053132119&partnerID=8YFLogxK
U2 - 10.1016/j.carbon.2018.07.062
DO - 10.1016/j.carbon.2018.07.062
M3 - Article
AN - SCOPUS:85053132119
SN - 0008-6223
VL - 139
SP - 1027
EP - 1034
JO - Carbon
JF - Carbon
ER -