APPARATUS AND METHOD FOR PLASMA SYNTHESIS OF GRAPHITIC PRODUCTS INCLUDING GRAPHENE

Dale Andrew Pennington; Aaron Robert Clayton; Katarzyna Luiza Juda; Catharina Paukner; Lukasz Kurzepa; Robert Henry St. John Cooper; Krzysztof Kazimierz Koziol; Jerome Yi-Zhe Joaug

Patent

Atlas literature

Patent

US 11,802,052 B2

APPARATUS AND METHOD FOR PLASMA SYNTHESIS OF GRAPHITIC PRODUCTS INCLUDING GRAPHENE

Dale Andrew Pennington, Aaron Robert Clayton, Katarzyna Luiza Juda, Catharina Paukner et al.

LEVIDIAN NANOSYSTEMS LIMITED, Cambridge (GB)·Oct. 31, 2023·US

Drawings

Patent drawings and their descriptions. Click a drawing to enlarge it.

FIG. 1

FIG. 1 illustrates an embodiment of the present invention, 10 including a plasma nozzle, afterglow reaction chamber and hot gas ﬁlter, for the plasma synthesis …

FIG. 2

FIG. 2 is a simpliﬁed drawing of the plasma nozzle of

FIG. 3

FIG. 3 illustrates the interface between the plasma nozzle, wave guide and reaction chamber with a purging ring;

FIG. 4

FIG. 4 shows a computational ﬂuid dynamics (CFD) simulation showing a triple vortex structure;

FIG. 5

FIG. 5 illustrates a CFD model of a twin nozzle using offset tangent planes;

FIG. 6

FIG. 6 illustrates a plasma nozzle, modiﬁed to prevent carbon build up by tapering the exit, with an additional channel to allow constant cooling via inert gas …

FIG. 7

FIGS. 7 and 8 present transmission electron micrographs of synthesised graphitic carbon material;

FIG. 8

FIG. 9

FIG. 9 presents transmission electron micrographs of graphitic carbon material synthesised at 2 kW microwave power, 24 L/min N₂+6 L/min mains natural gas (NG) …

FIG. 10

FIG. 10 presents a Raman spectrum of a graphitic carbon sample synthesised at 2 kW, 24 L/min N₂+6 L/min CH₄ ﬂow rate;

FIG. 11

FIGS. 11-13 present further transmission electron micro- graphs of synthesised graphitic carbon material;

FIG. 12

FIG. 12—15 L/min Ar, 22 L/min NG, 6 kW, HGF B₂

FIG. 13

FIG. 13—6 L/min Ar, 22 L/min NG, 6 kW, bag ﬁlter Example 4: Experiments with CO₂ and Associated TEM Analysis

FIG. 14

FIG. 14 presents TEM analysis of carbon materials syn- thesised at 6 kW, 21.5 L/min of Natural Gas, 5 L/min of CO2;

FIG. 15

FIG. 15 presents further transmission electron micro- graphs of synthesised carbon materials;

FIG. 16

FIG. 16 presents Raman spectra of samples of carbon materials produced (in line with the TEM observations in

FIG. 17

FIG. 17 presents further transmission electron micro- graphs of synthesised carbon materials;

FIG. 18

FIG. 18 presents Raman spectra of samples obtained for 50 (a) Low NG (D/G 0.68, G/2D 1.2) vs (b) high NG (D/G 1.0, G/2D 1.8) ﬂows in argon at 5 kW microwave …

FIG. 19

FIG. 19 presents further transmission electron micro- graphs of synthesised carbon materials;

FIG. 20

FIG. 20 presents Raman spectra of samples obtained 55 using NG in helium for (a) 3 kW (D/G 0.73, G/2D 1.8) and (b) 6 kW (D/G 0.83, G/2D 1.3);

FIG. 21

FIG. 21 presents further transmission electron micro- graphs of synthesised carbon materials;

FIG. 22

FIG. 22 presents Raman spectra of samples obtained 60 using 3.6 U/min NG at kW in (a) argon (D/G 0.68, G/2D 1.2) and (b) helium (D/G 0.97, G/2D 1.8);

FIG. 23

FIG. 23 presents further transmission electron micro- graphs of synthesised carbon materials;

FIG. 24

FIG. 24 presents Raman spectra of samples obtained 65 using 3.6 L/min NG at 6 kW in (a) helium (D/G 0.83, G/2D 1.3) and (b) nitrogen (D/G 1.2, G/2D 1.5); B₂

FIG. 25

FIG. 25 is a series of schematic illustrations to explain the expression “chord central angle” in relation to the arrange- ment of plasma nozzles relative to …

FIG. 26

FIG. 26 illustrates an example of alternative apparatus for the plasma synthesis of graphitic products including gra- phene;

FIG. 27

FIG. 27 shows an experimentally-measured temperature proﬁle at a point 2 cm from the plasma zone during plasma ignition;

FIG. 28

FIG. 28 shows an experimentally-measured temperature proﬁle at a point 4 cm from the plasma zone during typical operation; and

FIG. 29

FIG. 29 shows a conﬁguration of thermocouples in the reaction chamber, as used to obtain the test results shown in

Claims

Claims define the patent's legal scope. Independent claims stand alone; dependent claims (nested) narrow them. Click a claim to expand its dependents.

1 independent · 8 dependent

1
Independentgraphenecarbon-containing speciesplasma synthesis apparatus for graphitic products
A method of synthesizing graphitic products including graphene, the method comprising: supplying a process gas to a plasma nozzle that is coupled to a reaction chamber, the process gas comprising a carbon-containing species; supplying radio frequency radiation to the process gas within the plasma nozzle, so as to produce a nonequilibrium plasma within the plasma nozzle, and passing the process gas through a radio frequency radiation ﬁeld within the plasma nozzle, to thereby cause cracking of the carbon-containing species within the plasma nozzle, wherein the radio frequency radia-tion comprises microwave radiation; forming multiple vortices in the process gas within the plasma nozzle and subjecting the multiple vortices to the microwave radiation; wherein the plasma nozzle is arranged such that an afterglow of the plasma extends into the reaction cham-ber, the cracked carbon-containing species also passes into the reaction chamber, and the cracked carbon-containing species recombines within the afterglow, so as to form the graphitic products including the gra-phene; applying cooling to the afterglow on exiting the plasma nozzle, wherein the cooling comprises one of water cooling or gas cooling; subjecting the reaction chamber to gas ﬁltration to collect solid carbon from the gas phase, wherein the gas ﬁltration is performed using a gas ﬁltration system that is attached above the reaction chamber and comprises an elongate chamber comprising one or more ﬁlter candles; and blowing gas through the elongate chamber to dislodge the graphitic products collected by the one or more ﬁlter candles as a result of the gas ﬁltration, to cause the graphitic products collected by the one or more ﬁlter candles to fall down, through the reaction chamber, for extraction through an exit at the bottom of the reaction chamber.
1. 2
  Dependent← claim 1
  The method according to claim 1, further comprising generating the plasma at substantially atmospheric pressure.
2. 3
  Dependent← claim 1natural gasCH₄C₂H₆C₂H₄C₃H₈C₄H₁₀
  The method according to claim 1, wherein the carbon-containing species comprises one of natural gas, CH4, C₂H6, C₂H4, C₃H₈ or C₄H10. 23 24
3. 4
  Dependent← claim 1ArN₂He
  The method according to claim 1, wherein the process gas further comprises a buffer gas, the buffer gas comprising one of argon, nitrogen, or helium; and wherein the ratio of carbon-containing species to buffer gas in the process gas is 50:50 or less; or around 20:80.
4. 5
  Dependent← claim 1CO₂
  The method according to claim 1, wherein the process gas further comprises a buffer gas, the buffer gas comprising carbon dioxide.
5. 6
  Dependent← claim 1
  The method according to claim 1, wherein the after-glow within the reaction chamber has an operating tempera-ture of lower than 3500° C., lower than 1000° C., or around 300° C.; and wherein the temperature outside the plasma nozzle, at the carbon formation point within the afterglow, is in the range of 800° C. to 1200° C.
6. 7
  Dependent← claim 1
  The method according to claim 1, further comprising delivering gas around an interface between the plasma nozzle and the reaction chamber.
7. 8
  Dependent← claim 1
  The method according to claim 1, further comprising extracting the graphitic products using a continuous extrac-tion process.
8. 9
  Dependent← claim 1
  The method according to claim 1, wherein the carbon-containing species is cracked without the process gas being introduced into a thermal zone; wherein no catalyst is used in forming the graphitic products; and wherein no external heating is applied during the forma-tion of the graphitic products. ∗ ∗ ∗ ∗ ∗

Device structures

Layer stacks claimed or described, ordered top of device to substrate.

plasma synthesis apparatus for graphitic products

No layer stack recorded.

Materials

Materials described outside the worked examples.

graphene

Synthesis Product

carbon-containing species

Process Gas Precursor

Process steps

Additional fabrication and treatment steps described in the patent.

Microwave Plasma Synthesis

Step 1

Temperature

300, 800, 1000, 1200, 3500°C

Process details

cooling:water cooling or gas cooling

catalyst:

Characterization

Measurements and analyses referenced in the patent, with their drawing references.

tem

TEM

FIGS. 7 and 8 present transmission electron micrographs of synthesised graphitic carbon material;

Figure references

FIG. 7

tem

Reported properties

Performance values and ranges asserted in the specification or claims.

Property	Value	Material
Thickness	50–500 nm	—
Duration

Cited prior art

Patents and literature cited by this patent (applicant and examiner references).

Cited patents · 25

US 5,349,154 A5,349,154 A * 9/1994 Harker..................... H05H 1/46examiner
US 6,099,696 A6,099,696 A 8/2000 Schwob
US 7,771,666 B27,771,666 B2 * 8/2010 De La Veaux......... B01J 19/088examiner
US 8,071,906 B28,071,906 B2 * 12/2011 Smiljanic............... B01J 19/088examiner

Why these are connected

Related documents with shared materials, methods, properties, or citations.

APPARATUS AND METHOD FOR PLASMA SYNTHESIS OF GRAPHITIC PRODUCTS INCLUDING GRAPHENE | Matter42 Literature

Cited non-patent literature · 7

WO 2005058755 A1—translation (Year: 2005).
United Kingdom Search Report in counterpart patent application No. GB1510364.1 dated Jun. 25, 2015. International Search Report in counterpart patent application No. PCT/GB2015/051745 dated Aug. 19, 2015. Novoselov, K. S. et al., Nature, a roadmap for graphene, vol. 490, pp. 192-200, Oct. 2012. Segal, M., Nature Nanotechnology, Selling graphene by the ton, vol. 4, pp. 612-614, Oct. 2009. Subrahmanyam, K. S. et al., The Journal of Physical Chemistry C
Letters, Simple method of preparing graphene ﬂakes by an arc- discharge method, vol. 113, pp. 4257-4259, Feb. 2009. Chen, Y. et al., Chemical Physics Letters, Mass-production of highly-crystalline few-layer graphene sheets by arc discharge in various H2-inert gas mixtures, vol. 538, pp. 72-76, Apr. 2012. Meunier, J. L. et al., 21st International Symposium on Plasma
Chemistry, Homogeneous nucleation of graphene nanoﬂakes (GNFs) in thermal plasma: Tuning the 2D nanoscale geometry, pp. 1-4, Aug. 2013. Anekawa, Y. et al., 21st International Symposium on Plasma
Chemistry, Synthesis of graphene-based conductive thin ﬁlms by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system, 2013. Tatarova, E. et al., Applied Physics Letters, Microwave plasma based single step method for free standing graphene synthesis at atmospheric conditions, vol. 103, pp. 134101-134105, Sep. 2013. Dato, A. et al., Chemical Communications, Clean and highly ordered graphene synthesized in the gas phase, pp. 6095-6097, Aug. 2009. Novoselov, K. S. et al., Science, Electric ﬁeld effect in atomically thin carbon ﬁlms, vol. 306, pp. 666-669, Oct. 2004. Castelain, M. et al., Chemical Communications, Supramolecular assembly of graphene with functionalized poly(ﬂuorene-alt- phenylene): the role of the anthraquinone pendant groups, vol. 47, pp. 7677-7679, May 2011. Yan, X. et al., Journal of Materials Chemistry, Solution-chemistry approach to graphene nanostructures, vol. 21, pp. 3295-3300, 2011. Emstev, K. et al., Nature Materials, Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide, vol. 8, pp. 203-207, Mar. 2009. Wurstbauer, U. et al., Carbon, Molecular beam growth of graphene nanocrystals on dielectric substrates, vol. 50, pp. 4822-4829, 2012. Dhar, S. et al., AIP Advances, a new route to graphene layers by selective laser ablation, vol. 1, p. 022109, 2011. McAllister, M. J. et al., Chemistry of Materials, Single sheet functionalized graphene by oxidation and thermal expansion of graphite, vol. 19, pp. 4396-4404, 2007. Vlassiouk, I. et al., Carbon, Large scale atmospheric pressure chemical vapor deposition of graphene, vol. 54, pp. 58-67, 2013. Reina, A. et al., Nano Letters, Large area, few-layer graphene ﬁlms on arbitrary substrates by chemical vapor deposition, vol. 9, No. 1, pp. 30-35, 2009.
Microwave plasmas applied for the synthesis of free standing graphene sheets. Angstron Materials; Vorbeck Materials in Jessup, Maryland; XG Sciences in East Lansing, Michigan. Hernandez, Y. et al., Nanotechnology, High-yield production of graphene by liquid-phase exfoliation of graphite, vol. 3, pp. 563- 568, Sep. 2008. Dato, A. et al., New Journal of Physics, Substrate-free microwave synthesis of graphene: experimental conditions and hydrocarbon precursors, vol. 12, p. 125013, 2010. E. Tatarova et al.,“Microwave plasmas applied for the synthesis of free standing graphene sheets”, Journal of Physics. D: Applied Physics 47, 385501, pp. 1-11, Aug. 22, 2014. Y. Wu et al., “Efficient and Large-Scale Synthesis of Few-Layered Graphene Using an Arc-Discharge Method and Conductivity Stud- ies of the Resulting Films”, Nano Research, vol. 3(9), pp. 661-669, Sep. 2010. M. Leins et al., “An Atmospheric Pressure Microwave Plasma Torch”, 2011. P.L. Fauchais et al., Thermal Spray Fundamentals: From Powder to
Overview of Thermal Spray. Part, Chapter 2, “Overview of Thermal Spray,” Springer: New York, pp. 17-72, 2014. S. Heidenreich et al., Fuel, “Hot gas ﬁltration—a review”, vol. 104, pp. 83-94, 2013. C.-J. Chen et al.,“The Thermal Decomposition of Methane. I. Kinetics of the Primary Decomposition to C2H6 + H2; Rate Constant for the Homogeneous Unimolecular Dissociation of Meth- ane and its Pressure Dependence”, Canadian Journal of Chemistry, vol. 53, pp. 3580-3590, 1975. Yang, Z., et al., “Differentiation of alkane isomers through binding energy spectra and total momentum cross sections”, New J. Chem., vol. 38, pp. 1031-1039, 2014. Sun, Q., et al., “Methane activation on Fe4 cluster: a density functional theory study”, Chemical Physics Letters 550, pp. 41-46, 2012. Merlo-Sosa, L., et al., “Dodecane decomposition in a radio- frequency (RF) plasma reactor”, International Journal of Chemical Reactor Engineering, vol. 3, p. 1542, 2005. Ogungbesan, B., et al., “Experimental validation of local thermal equilibrium in a MW plasma torch for hydrogen production”, Int. J. Hyd. Energy 38, pp. 15210-15218, 2013. Juda, K. L., et al., “Large scale synthesis of carbon nanoforms in a novel atmospheric pressure microwave plasma reactor”, Proceed- ings of ISPC 21, Aug. 2013.

Cited non-patent literature · 7

WO 2005058755 A1—translation (Year: 2005).
United Kingdom Search Report in counterpart patent application No. GB1510364.1 dated Jun. 25, 2015. International Search Report in counterpart patent application No. PCT/GB2015/051745 dated Aug. 19, 2015. Novoselov, K. S. et al., Nature, a roadmap for graphene, vol. 490, pp. 192-200, Oct. 2012. Segal, M., Nature Nanotechnology, Selling graphene by the ton, vol. 4, pp. 612-614, Oct. 2009. Subrahmanyam, K. S. et al., The Journal of Physical Chemistry C
Letters, Simple method of preparing graphene ﬂakes by an arc- discharge method, vol. 113, pp. 4257-4259, Feb. 2009. Chen, Y. et al., Chemical Physics Letters, Mass-production of highly-crystalline few-layer graphene sheets by arc discharge in various H2-inert gas mixtures, vol. 538, pp. 72-76, Apr. 2012. Meunier, J. L. et al., 21st International Symposium on Plasma
Chemistry, Homogeneous nucleation of graphene nanoﬂakes (GNFs) in thermal plasma: Tuning the 2D nanoscale geometry, pp. 1-4, Aug. 2013. Anekawa, Y. et al., 21st International Symposium on Plasma
Chemistry, Synthesis of graphene-based conductive thin ﬁlms by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system, 2013. Tatarova, E. et al., Applied Physics Letters, Microwave plasma based single step method for free standing graphene synthesis at atmospheric conditions, vol. 103, pp. 134101-134105, Sep. 2013. Dato, A. et al., Chemical Communications, Clean and highly ordered graphene synthesized in the gas phase, pp. 6095-6097, Aug. 2009. Novoselov, K. S. et al., Science, Electric ﬁeld effect in atomically thin carbon ﬁlms, vol. 306, pp. 666-669, Oct. 2004. Castelain, M. et al., Chemical Communications, Supramolecular assembly of graphene with functionalized poly(ﬂuorene-alt- phenylene): the role of the anthraquinone pendant groups, vol. 47, pp. 7677-7679, May 2011. Yan, X. et al., Journal of Materials Chemistry, Solution-chemistry approach to graphene nanostructures, vol. 21, pp. 3295-3300, 2011. Emstev, K. et al., Nature Materials, Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide, vol. 8, pp. 203-207, Mar. 2009. Wurstbauer, U. et al., Carbon, Molecular beam growth of graphene nanocrystals on dielectric substrates, vol. 50, pp. 4822-4829, 2012. Dhar, S. et al., AIP Advances, a new route to graphene layers by selective laser ablation, vol. 1, p. 022109, 2011. McAllister, M. J. et al., Chemistry of Materials, Single sheet functionalized graphene by oxidation and thermal expansion of graphite, vol. 19, pp. 4396-4404, 2007. Vlassiouk, I. et al., Carbon, Large scale atmospheric pressure chemical vapor deposition of graphene, vol. 54, pp. 58-67, 2013. Reina, A. et al., Nano Letters, Large area, few-layer graphene ﬁlms on arbitrary substrates by chemical vapor deposition, vol. 9, No. 1, pp. 30-35, 2009.
Microwave plasmas applied for the synthesis of free standing graphene sheets. Angstron Materials; Vorbeck Materials in Jessup, Maryland; XG Sciences in East Lansing, Michigan. Hernandez, Y. et al., Nanotechnology, High-yield production of graphene by liquid-phase exfoliation of graphite, vol. 3, pp. 563- 568, Sep. 2008. Dato, A. et al., New Journal of Physics, Substrate-free microwave synthesis of graphene: experimental conditions and hydrocarbon precursors, vol. 12, p. 125013, 2010. E. Tatarova et al.,“Microwave plasmas applied for the synthesis of free standing graphene sheets”, Journal of Physics. D: Applied Physics 47, 385501, pp. 1-11, Aug. 22, 2014. Y. Wu et al., “Efficient and Large-Scale Synthesis of Few-Layered Graphene Using an Arc-Discharge Method and Conductivity Stud- ies of the Resulting Films”, Nano Research, vol. 3(9), pp. 661-669, Sep. 2010. M. Leins et al., “An Atmospheric Pressure Microwave Plasma Torch”, 2011. P.L. Fauchais et al., Thermal Spray Fundamentals: From Powder to
Overview of Thermal Spray. Part, Chapter 2, “Overview of Thermal Spray,” Springer: New York, pp. 17-72, 2014. S. Heidenreich et al., Fuel, “Hot gas ﬁltration—a review”, vol. 104, pp. 83-94, 2013. C.-J. Chen et al.,“The Thermal Decomposition of Methane. I. Kinetics of the Primary Decomposition to C2H6 + H2; Rate Constant for the Homogeneous Unimolecular Dissociation of Meth- ane and its Pressure Dependence”, Canadian Journal of Chemistry, vol. 53, pp. 3580-3590, 1975. Yang, Z., et al., “Differentiation of alkane isomers through binding energy spectra and total momentum cross sections”, New J. Chem., vol. 38, pp. 1031-1039, 2014. Sun, Q., et al., “Methane activation on Fe4 cluster: a density functional theory study”, Chemical Physics Letters 550, pp. 41-46, 2012. Merlo-Sosa, L., et al., “Dodecane decomposition in a radio- frequency (RF) plasma reactor”, International Journal of Chemical Reactor Engineering, vol. 3, p. 1542, 2005. Ogungbesan, B., et al., “Experimental validation of local thermal equilibrium in a MW plasma torch for hydrogen production”, Int. J. Hyd. Energy 38, pp. 15210-15218, 2013. Juda, K. L., et al., “Large scale synthesis of carbon nanoforms in a novel atmospheric pressure microwave plasma reactor”, Proceed- ings of ISPC 21, Aug. 2013.

Cited non-patent literature · 7

WO 2005058755 A1—translation (Year: 2005).
United Kingdom Search Report in counterpart patent application No. GB1510364.1 dated Jun. 25, 2015. International Search Report in counterpart patent application No. PCT/GB2015/051745 dated Aug. 19, 2015. Novoselov, K. S. et al., Nature, a roadmap for graphene, vol. 490, pp. 192-200, Oct. 2012. Segal, M., Nature Nanotechnology, Selling graphene by the ton, vol. 4, pp. 612-614, Oct. 2009. Subrahmanyam, K. S. et al., The Journal of Physical Chemistry C
Letters, Simple method of preparing graphene ﬂakes by an arc- discharge method, vol. 113, pp. 4257-4259, Feb. 2009. Chen, Y. et al., Chemical Physics Letters, Mass-production of highly-crystalline few-layer graphene sheets by arc discharge in various H2-inert gas mixtures, vol. 538, pp. 72-76, Apr. 2012. Meunier, J. L. et al., 21st International Symposium on Plasma
Chemistry, Homogeneous nucleation of graphene nanoﬂakes (GNFs) in thermal plasma: Tuning the 2D nanoscale geometry, pp. 1-4, Aug. 2013. Anekawa, Y. et al., 21st International Symposium on Plasma
Chemistry, Synthesis of graphene-based conductive thin ﬁlms by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system, 2013. Tatarova, E. et al., Applied Physics Letters, Microwave plasma based single step method for free standing graphene synthesis at atmospheric conditions, vol. 103, pp. 134101-134105, Sep. 2013. Dato, A. et al., Chemical Communications, Clean and highly ordered graphene synthesized in the gas phase, pp. 6095-6097, Aug. 2009. Novoselov, K. S. et al., Science, Electric ﬁeld effect in atomically thin carbon ﬁlms, vol. 306, pp. 666-669, Oct. 2004. Castelain, M. et al., Chemical Communications, Supramolecular assembly of graphene with functionalized poly(ﬂuorene-alt- phenylene): the role of the anthraquinone pendant groups, vol. 47, pp. 7677-7679, May 2011. Yan, X. et al., Journal of Materials Chemistry, Solution-chemistry approach to graphene nanostructures, vol. 21, pp. 3295-3300, 2011. Emstev, K. et al., Nature Materials, Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide, vol. 8, pp. 203-207, Mar. 2009. Wurstbauer, U. et al., Carbon, Molecular beam growth of graphene nanocrystals on dielectric substrates, vol. 50, pp. 4822-4829, 2012. Dhar, S. et al., AIP Advances, a new route to graphene layers by selective laser ablation, vol. 1, p. 022109, 2011. McAllister, M. J. et al., Chemistry of Materials, Single sheet functionalized graphene by oxidation and thermal expansion of graphite, vol. 19, pp. 4396-4404, 2007. Vlassiouk, I. et al., Carbon, Large scale atmospheric pressure chemical vapor deposition of graphene, vol. 54, pp. 58-67, 2013. Reina, A. et al., Nano Letters, Large area, few-layer graphene ﬁlms on arbitrary substrates by chemical vapor deposition, vol. 9, No. 1, pp. 30-35, 2009.
Microwave plasmas applied for the synthesis of free standing graphene sheets. Angstron Materials; Vorbeck Materials in Jessup, Maryland; XG Sciences in East Lansing, Michigan. Hernandez, Y. et al., Nanotechnology, High-yield production of graphene by liquid-phase exfoliation of graphite, vol. 3, pp. 563- 568, Sep. 2008. Dato, A. et al., New Journal of Physics, Substrate-free microwave synthesis of graphene: experimental conditions and hydrocarbon precursors, vol. 12, p. 125013, 2010. E. Tatarova et al.,“Microwave plasmas applied for the synthesis of free standing graphene sheets”, Journal of Physics. D: Applied Physics 47, 385501, pp. 1-11, Aug. 22, 2014. Y. Wu et al., “Efficient and Large-Scale Synthesis of Few-Layered Graphene Using an Arc-Discharge Method and Conductivity Stud- ies of the Resulting Films”, Nano Research, vol. 3(9), pp. 661-669, Sep. 2010. M. Leins et al., “An Atmospheric Pressure Microwave Plasma Torch”, 2011. P.L. Fauchais et al., Thermal Spray Fundamentals: From Powder to
Overview of Thermal Spray. Part, Chapter 2, “Overview of Thermal Spray,” Springer: New York, pp. 17-72, 2014. S. Heidenreich et al., Fuel, “Hot gas ﬁltration—a review”, vol. 104, pp. 83-94, 2013. C.-J. Chen et al.,“The Thermal Decomposition of Methane. I. Kinetics of the Primary Decomposition to C2H6 + H2; Rate Constant for the Homogeneous Unimolecular Dissociation of Meth- ane and its Pressure Dependence”, Canadian Journal of Chemistry, vol. 53, pp. 3580-3590, 1975. Yang, Z., et al., “Differentiation of alkane isomers through binding energy spectra and total momentum cross sections”, New J. Chem., vol. 38, pp. 1031-1039, 2014. Sun, Q., et al., “Methane activation on Fe4 cluster: a density functional theory study”, Chemical Physics Letters 550, pp. 41-46, 2012. Merlo-Sosa, L., et al., “Dodecane decomposition in a radio- frequency (RF) plasma reactor”, International Journal of Chemical Reactor Engineering, vol. 3, p. 1542, 2005. Ogungbesan, B., et al., “Experimental validation of local thermal equilibrium in a MW plasma torch for hydrogen production”, Int. J. Hyd. Energy 38, pp. 15210-15218, 2013. Juda, K. L., et al., “Large scale synthesis of carbon nanoforms in a novel atmospheric pressure microwave plasma reactor”, Proceed- ings of ISPC 21, Aug. 2013.

Cited non-patent literature · 7

WO 2005058755 A1—translation (Year: 2005).
United Kingdom Search Report in counterpart patent application No. GB1510364.1 dated Jun. 25, 2015. International Search Report in counterpart patent application No. PCT/GB2015/051745 dated Aug. 19, 2015. Novoselov, K. S. et al., Nature, a roadmap for graphene, vol. 490, pp. 192-200, Oct. 2012. Segal, M., Nature Nanotechnology, Selling graphene by the ton, vol. 4, pp. 612-614, Oct. 2009. Subrahmanyam, K. S. et al., The Journal of Physical Chemistry C
Letters, Simple method of preparing graphene ﬂakes by an arc- discharge method, vol. 113, pp. 4257-4259, Feb. 2009. Chen, Y. et al., Chemical Physics Letters, Mass-production of highly-crystalline few-layer graphene sheets by arc discharge in various H2-inert gas mixtures, vol. 538, pp. 72-76, Apr. 2012. Meunier, J. L. et al., 21st International Symposium on Plasma
Chemistry, Homogeneous nucleation of graphene nanoﬂakes (GNFs) in thermal plasma: Tuning the 2D nanoscale geometry, pp. 1-4, Aug. 2013. Anekawa, Y. et al., 21st International Symposium on Plasma
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