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Title
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Ultrasonication induces oxygenated species and defects onto exfoliated graphene
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Author
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Abstract
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| The effect of ultrasonication parameters, such as time and power applied, to exfoliate graphite in o-dichlorobenzene (o-DCB) and N-methyl-1,2-pyrrolidone (NMP) was examined. It was found that the concentration of graphene was higher in o-DCB, while its dispersibility was increased when sonication was applied for a longer period and/or at higher power. However, spectroscopic examination by X-ray photoelectron spectroscopy (XPS) revealed that ultrasonication causes defects and induces oxygen functional groups in the form of carboxylic acids and ethers/epoxides onto the graphene lattice. Additional proof for the latter arose from Raman, IR, and thermogravimetry studies. The carboxylic acids and ethers/epoxides onto exfoliated graphene were derived from air during ultrasonication and found independent of the solvent used for the exfoliation and the power and/or time ultrasonication applied. Quantitative evaluation of the amount of oxygenated species present on exfoliated graphene as performed by high-resolution XPS revealed that the relative oxygen percentage was higher when exfoliation was performed in NMP. Finally, the sonication time and/or power affected the oxygen content on exfoliated graphene, since extended ultrasonication resulted in a decrease in the oxygen content on exfoliated graphene, with a simultaneous increase of defected sp(3) carbon atoms. |
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Language
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English
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Source (journal)
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The journal of physical chemistry: C : nanomaterials and interfaces. - Washington, D.C., 2007, currens
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Publication
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Washington, D.C.
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2013
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ISSN
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1932-7447
[print]
1932-7455
[online]
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DOI
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10.1021/JP4057048
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Volume/pages
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117
:44
(2013)
, p. 23272-23278
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ISI
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000326845400090
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Full text (Publisher's DOI)
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