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@article{54354,
   author = {Jašek, Ondřej and Toman, Jozef and Šnírer, Miroslav and Jurmanová, Jana and Kudrle, Vít and Michalička, Jan and Všianský, Dalibor and Pavliňák, David},
   article_number = {50},
   doi = {http://dx.doi.org/10.1088/1361-6528/ac24c3},
   keywords = {high temperature; dehydrogenation; graphene; growth mechanism; microwave plasma},
   language = {eng},
   issn = {0957-4484},
   journal = {Nanotechnology},
   title = {Microwave plasma-based high temperature dehydrogenation of hydrocarbons and alcohols as a single route to highly efficient gas phase synthesis of freestanding graphene},
   url = {https://doi.org/10.1088/1361-6528/ac24c3},
   volume = {32},
   year = {2021}
}

TY  - JOUR
ID  - 54354
AU  - Jašek, Ondřej - Toman, Jozef - Šnírer, Miroslav - Jurmanová, Jana - Kudrle, Vít - Michalička, Jan - Všianský, Dalibor - Pavliňák, David
PY  - 2021
TI  - Microwave plasma-based high temperature dehydrogenation of hydrocarbons and alcohols as a single route to highly efficient gas phase synthesis of freestanding graphene
JF  - Nanotechnology
VL  - 32
IS  - 50
SP  - "505608"
EP  - "505608"
PB  - IOP Publishing Ltd.
SN  - 0957-4484
KW  - high temperature
KW  - dehydrogenation
KW  - graphene
KW  - growth mechanism
KW  - microwave plasma
UR  - https://doi.org/10.1088/1361-6528/ac24c3
N2  - Understanding underlying processes behind the simple and easily scalable graphene synthesis methods enables their large-scale deployment in the emerging energy storage and printable device applications. Microwave plasma decomposition of organic precursors forms a high-temperature environment, above 3000 K, where the process of catalyst-free dehydrogenation and consequent formation of C2 molecules leads to nucleation and growth of high-quality few-layer graphene (FLG). In this work, we show experimental evidence that a high-temperature environment with a gas mixture of H2 and acetylene, C2H2, leads to a transition from amorphous to highly crystalline material proving the suggested dehydrogenation mechanism. The overall conversion efficiency of carbon to FLG reached up to 47%, three times as much as for methane or ethanol, and increased with increasing microwave power (i.e. with the size of the high-temperature zone) and hydrocarbon flow rate. The yield decreased with decreasing C:H ratio while the best quality FLG (low D/G–0.5 and high 2D/G–1.5 Raman band ratio) was achieved for C:H ratio of 1:3. The structures contained less than 1 at% of oxygen. No additional hydrogen was necessary for the synthesis of FLG from higher alcohols having the same stoichiometry, 1-propanol and isopropanol, but the yield was lower, 15%, and dependent on the atom arrangement of the precursor. The prepared FLG nanopowder was analyzed by scanning electron microscopy, Raman, x-ray photoelectron spectroscopy, and thermogravimetry. Microwave plasma was monitored by optical emission spectroscopy.
ER  - 

JAŠEK, Ondřej, Jozef TOMAN, Miroslav ŠNÍRER, Jana JURMANOVÁ, Vít KUDRLE, Jan MICHALIČKA, Dalibor VŠIANSKÝ a David PAVLIŇÁK. Microwave plasma-based high temperature dehydrogenation of hydrocarbons and alcohols as a single route to highly efficient gas phase synthesis of freestanding graphene. \textit{Nanotechnology}. IOP Publishing Ltd., 2021, roč.~32, č.~50, s.~''505608'', 11 s. ISSN~0957-4484. Dostupné z: https://dx.doi.org/10.1088/1361-6528/ac24c3.