TY - JOUR
T1 - Effect of hydrogen concentration on graphene synthesis using microwave-driven plasma-mediated methane cracking
AU - Singh, Madhu
AU - Sengupta, Arupananda
AU - Zeller, Kurt
AU - Skoptsov, George
AU - Vander Wal, Randy L.
N1 - Funding Information:
H Quest Vanguard, Inc. is a privately held technology company, based in Pittsburgh, Pennsylvania, focused on the development and commercialization of novel hydrocarbon conversion technologies. This material is based on work supported by the Department of Energy, Office of Science through subaward agreement no. 186949 with H Quest Vanguard, Inc . under the Prime Award DE-SC0015895 Phase I SBIR. Characterizations (TEM, TGA, XRD, Raman, FTIR, EELS) were performed using the facilities of the Materials Research Institute at The Pennsylvania State University. HRTEM guidance from Dr. Jennifer Gray and Dr. Ke Wang is gratefully acknowledged. FTIR spectroscopy was performed and analyzed with the help and guidance of Dr. Tawanda J. Zimudzi at the Materials Characterization Laboratory. Arupananda Sengupta and Madhu Singh have contributed equally to this work.
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2019/3
Y1 - 2019/3
N2 - Gas phase graphene forms as an aerosol in a microwave plasma among other carbon forms. Consisting of 2–6 sheets per stack with dimensions between 100 and 500 nm, it is referred to as nanographene (NG). Surprisingly, increasing H/C ratio in the feedstock increases the relative graphitic content of the product. Dependence of the different carbon forms upon H/C ratio of the gas feed mixture is shown across multiple analytical characterizations. Attributes of (a) phase quality (pristine nature of NG) and (b) phase quantity (how much NG forms relative to other carbon sp2 phases) are addressed. Phase identification of the forms is performed via transmission electron microscopy with quantification by thermogravimetric analysis, assessing their respective oxidative reactivity benchmarked to commercially available similar carbon products applied as standards. X-ray diffraction differentiates these forms based on varied extent of graphitic structure. Electron energy loss spectroscopy assesses graphitic content by the ratio of sp2/sp3 bonding. Raman spectroscopy supports the observed shift in relative proportions of the carbon forms towards preferential graphitic content with increasing H/C. Selected area diffraction illustrates this for NG. Fringe analyses of nanostructure quantifies this shift for carbon particles. Infra-red spectroscopy reveals complementary C–H bonding as a measure of graphitic quality.
AB - Gas phase graphene forms as an aerosol in a microwave plasma among other carbon forms. Consisting of 2–6 sheets per stack with dimensions between 100 and 500 nm, it is referred to as nanographene (NG). Surprisingly, increasing H/C ratio in the feedstock increases the relative graphitic content of the product. Dependence of the different carbon forms upon H/C ratio of the gas feed mixture is shown across multiple analytical characterizations. Attributes of (a) phase quality (pristine nature of NG) and (b) phase quantity (how much NG forms relative to other carbon sp2 phases) are addressed. Phase identification of the forms is performed via transmission electron microscopy with quantification by thermogravimetric analysis, assessing their respective oxidative reactivity benchmarked to commercially available similar carbon products applied as standards. X-ray diffraction differentiates these forms based on varied extent of graphitic structure. Electron energy loss spectroscopy assesses graphitic content by the ratio of sp2/sp3 bonding. Raman spectroscopy supports the observed shift in relative proportions of the carbon forms towards preferential graphitic content with increasing H/C. Selected area diffraction illustrates this for NG. Fringe analyses of nanostructure quantifies this shift for carbon particles. Infra-red spectroscopy reveals complementary C–H bonding as a measure of graphitic quality.
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U2 - 10.1016/j.carbon.2018.11.082
DO - 10.1016/j.carbon.2018.11.082
M3 - Article
AN - SCOPUS:85059330224
VL - 143
SP - 802
EP - 813
JO - Carbon
JF - Carbon
SN - 0008-6223
ER -