Microwave plasmas applied for the synthesis of free standing graphene sheets
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Authors
Tatarova, E.
Henriques, J.
Dias, A.
Botelho do Rego, A.M.
Ferraria, A.M.
Abrashev, M.V.
Luhrs, Claudia C.
Phillips, Jonathan
Dias, F.M.
Ferreira, C.M.
Subjects
graphene
microwave plasma
ethanol
microwave plasma
ethanol
Advisors
Date of Issue
2014
Date
Publisher
Language
Abstract
Self-standing graphene sheets were synthesized using microwave plasmas driven by surface
waves at 2.45 GHz stimulating frequency and atmospheric pressure. The method is based on
injecting ethanol molecules through a microwave argon plasma environment, where
decomposition of ethanol molecules takes place. The evolution of the ethanol decomposition
was studied in situ by plasma emission spectroscopy. Free gas-phase carbon atoms created in
the plasma diffuse into colder zones, both in radial and axial directions, and aggregate into solid
carbon nuclei. The main part of the solid carbon is gradually withdrawn from the hot region of
the plasma in the outlet plasma stream where nanostructures assemble and grow. Externally
forced heating in the assembly zone of the plasma reactor has been applied to engineer the
structural qualities of the assembled nanostructures. The synthesized graphene sheets have
been analysed by Raman spectroscopy, scanning electron microscopy, high-resolution
transmission electron microscopy and x-ray photoelectron spectroscopy. The presence of sp3
carbons is reduced by increasing the gas temperature in the assembly zone of the plasma
reactor. As a general trend, the number of mono-layers decreases when the wall temperature
increases from 60 to 100 ◦C. The synthesized graphene sheets are stable and highly ordered.
Type
Article
Description
The article of record as published may be located at http://dx.doi.org/10.1088/0022-3727/47/38/385501
Series/Report No
Department
Mechanical and Aerospace Engineering
Organization
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NPS Report Number
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Funding
Format
Citation
J. Phys. D: Appl. Phys. 47 (2014) 385501 (11pp)
Distribution Statement
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.