WO2017055618A1 - Method of producing graphene structures - Google Patents

Method of producing graphene structures Download PDF

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Publication number
WO2017055618A1
WO2017055618A1 PCT/EP2016/073525 EP2016073525W WO2017055618A1 WO 2017055618 A1 WO2017055618 A1 WO 2017055618A1 EP 2016073525 W EP2016073525 W EP 2016073525W WO 2017055618 A1 WO2017055618 A1 WO 2017055618A1
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WIPO (PCT)
Prior art keywords
continuous
graphene
substrate
optionally
continuous substrate
Prior art date
Application number
PCT/EP2016/073525
Other languages
French (fr)
Inventor
Donal Paul O'Flynn
William Franklin Shelley
Original Assignee
O'flynn Donal Paul
William Franklin Shelley
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP15188248.7A external-priority patent/EP3150551A1/en
Priority claimed from EP15196596.9A external-priority patent/EP3173379A1/en
Application filed by O'flynn Donal Paul, William Franklin Shelley filed Critical O'flynn Donal Paul
Publication of WO2017055618A1 publication Critical patent/WO2017055618A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/186—Preparation by chemical vapour deposition [CVD]

Definitions

  • This invention relates to a method for producing graphene structures by providing a substrate; forming a graphene on or at the substrate; and removing the substrate to provide a graphene structure. Also disclosed are graphene structures produced by that method; a further method for producing graphene fibres, and the graphene fibres produced by that further method. Background to the Invention
  • the present invention relates to a method for producing structures formed from graphene.
  • the present invention provides a method for producing high modulus, high tensile strength carbon fibres.
  • High performance carbon fibres are primarily made from a polyacrylonitrile (PAN) precursor fibre that is oxidized and then carbonized. 50% of the cost of the end-product carbon fibre is attributed to the PAN precursor. 40% of the total cost of production of PAN-based carbon fibres comes from the energy intensive, high temperature oxidation and carbonization processes. The final 10% of the cost is attributed to post treatment of the fibres.
  • Research into carbon fibres produced from other precursors such as pitch, polyolefin, and lignin have failed to produce carbon fibres with the requisite tensile strength and elastic modulus.
  • the process variables that have a large impact on the final cost of producing structures formed from graphene include the lifetime of the substrate in service, and the residence time of the substrate in the hot zone of the reaction chamber or during graphene deposition.
  • the substrate would have the lowest possible initial cost and the longest possible service lifetime.
  • the residence time of the substrate in the hot zone of the reaction chamber or environment should be minimized, so as to maximize graphene production rates in terms of structure length over time, for example, by increasing the temperature of the reaction chamber or environment, thus speeding the kinetics of hydrocarbon dissociation.
  • the kinetics of hydrocarbon dissociation can also be improved by using Le Chatellier's principle and removing product hydrogen gas from the reaction chamber or environment as it is liberated from the hydrocarbon source gas. It is also desirable to deposit the highest number of graphene layers on the substrate in the shortest possible time, so as to maximize the capture rate of graphene over a given residence time.
  • the present invention takes advantage of the unique properties of graphene that can be produced from various cheap hydrocarbon precursors and on various substrates.
  • a method for producing graphene structures comprising the steps of: (a) providing a continuous substrate;
  • a method for producing graphene fibres comprising the steps of:
  • the providing more than one graphene tube step comprises providing more than one graphene tube produced by a method according to the first or second aspect of the present invention.
  • a method for producing graphene films comprising the steps of:
  • discontinuous is meant having no point of discontinuity, and is intended to exclude any break, gap, opening, similar interruption, or a combination thereof, to the substrate.
  • the step of providing a continuous substrate comprises: providing a reaction environment prior to the step of forming graphene on or at the continuous substrate.
  • continuous is meant a substrate having no point of discontinuity, optionally when the substrate is within the reaction environment; and is intended to exclude a substrate having any break, gap, opening, similar interruption, or a combination thereof, to the substrate, optionally when the substrate is within the reaction environment.
  • the continuous substrate has no point of discontinuity. Further optionally, the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate. Still further optionally, the continuous substrate has no point of discontinuity when the substrate is within the reaction environment. Still further optionally, the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate when the substrate is within the reaction environment.
  • the method comprises the steps of
  • substrate optionally a continuous generally planar substrate
  • the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment. Further optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate through the reaction environment, prior to the step of forming graphene on or at the continuous substrate. Still further optionally, the method further comprises the step of continually passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment, prior to the step of forming graphene on or at the continuous substrate.
  • the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment; forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment; and removing the graphene structure from the continuous substrate.
  • the removing step is conducted outside the reaction environment. Further optionally, the removing step comprises removing the graphene structure from the continuous substrate when the substrate is outside the reaction environment.
  • the reaction environment is defined by a reaction chamber.
  • the continuous substrate optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has no point of discontinuity when the substrate is within the reaction chamber.
  • the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate when the substrate is within the reaction chamber,
  • the method comprises the steps of
  • substrate optionally a continuous generally planar substrate
  • the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber. Further optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate through the reaction chamber prior to the step of forming graphene on or at the continuous substrate. Still further optionally, the method further comprises the step of continually passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber prior to the step of forming graphene on or at the continuous substrate.
  • the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction chamber; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber;
  • the removing step is conducted outside the reaction chamber. Further optionally, the removing step comprises removing the graphene structure from the continuous substrate when the substrate is outside the reaction chamber.
  • the forming step comprises continually forming graphene on or at the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, to provide the graphene structure.
  • the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; continually forming graphene on or at the continuous substrate to provide a graphene structure; and removing the graphene structure from the continuous substrate.
  • the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment or a reaction chamber; continually forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment or the reaction chamber; and removing the graphene structure from the continuous substrate.
  • the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment or a reaction chamber; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment or the reaction chamber; forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment or the reaction chamber; and removing the graphene structure from the continuous substrate.
  • the continuous substrate can be any substrate on or at which graphene can be formed.
  • the continuous substrate can be any substrate on or at which graphene can be formed and from which the formed graphene structure can be removed.
  • the continuous substrate is a continuous ribbon.
  • the continuous substrate is a continuous planar ribbon.
  • the continuous ribbon can be of any cross-sectional dimension required to produce a graphene tube.
  • the continuous substrate comprises at least one continuous ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous ribbons.
  • the continuous substrate comprises at least one continuous planar ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar ribbons.
  • the continuous substrate is a continuous plate.
  • the continuous substrate is a continuous planar plate.
  • the continuous plate can be of any cross-sectional dimension required to produce a graphene film.
  • the continuous substrate is a continuous wire.
  • the continuous substrate is a continuous cylindrical wire.
  • the continuous wire can be of any cross-sectional shape required to produce the graphene tube.
  • the continuous substrate comprises at least one continuous wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous wires. Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical wires. Optionally, the continuous substrate comprises a plurality of continuous substrates.
  • the continuous substrate optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has an uninterrupted length of more than 1 m, optionally more than 10m, further optionally more than 100m, further optionally more than 1000m.
  • the continuous substrate optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has an uninterrupted length of more than 1 m within the reaction environment, optionally more than 10m within the reaction environment, further optionally more than 100m within the reaction environment, further optionally more than 1000m within the reaction environment.
  • the continuous substrate forms a loop. Further optionally, the continuous substrate forms a continuous (or endless) loop.
  • the continuous substrate is formed from a material having an elastic modulus (E) of 75 - 463 gigapascals. Further optionally, the continuous substrate is formed from a material having an elastic modulus (E) of 75, 89, 107, 1 10, 162, 186, 189, 207, 220, 279, 407, or 463 gigapascals.
  • the continuous substrate is formed from a material having an ultimate tensile strength (UTS) of 48.3 - 4840 megapascals. Further optionally or additionally, the continuous substrate is formed from a material having an ultimate tensile strength (UTS) of 48.3, 83, 220, 262, 330, 480, 552, 586, 655, 1070, or 4840 megapascals.
  • UTS ultimate tensile strength
  • the continuous substrate is formed from a material having an annealed elongation of 2 - 70%. Further optionally or additionally, the continuous substrate is formed from a material having an annealed elongation of 2, 3.15, 15, 25, 30, 35, 40, 44, 45, or 70%.
  • the continuous substrate is formed from a material having a melting point of 1085 - 3400°C. Further optionally or additionally, the continuous substrate is formed from a material having a melting point of 1085, 1220, 1399, 1400, 1420, 1427, 1453, 1538, 1665, 1800, 1907, 3186, 3400°C.
  • the continuous substrate is formed from a material having a density of 2.203 - 21.02 g/cm 3 . Further optionally or additionally, the continuous substrate is formed from a material having a density of 2.203, 2.65, 4.5, 7.14, 7.87, 8.02, 8.6, 8.73, 8.85, 8.9, 8.94, 19.3, or 21.02 g/cm 3 . Optionally or additionally, the continuous substrate is formed from a material having a coefficient of thermal expansion (CTE) of 0.5 - 17.3 ppm/°C.
  • CTE coefficient of thermal expansion
  • the continuous substrate is formed from a material having a coefficient of thermal expansion (CTE) of 0.5, 4.44, 6.2, 7.14, 8.1 , 1 1.8, 12.8, 13.7, 14.9, 16.42, 16.8, or 17.3 ppm/°C.
  • CTE coefficient of thermal expansion
  • the continuous substrate is formed from a material selected from copper, nickel, chromium, stainless steel, silicon dioxide, aluminium (III) oxide, iron, titanium, tungsten, rhenium, constantan, a nickel/chromium alloy such as Chromel® from Concept Alloys, Inc; a nickel, manganese, aluminium and silicon alloy such as Alumel® from Concept Alloys, Inc; basalt, polyethylene, and mixtures each thereof.
  • the continuous substrate is formed from a metal or metal alloy. Further optionally, the continuous substrate is formed from a plastic metal or metal alloy. Further optionally, the continuous substrate is formed from a ductile metal or metal alloy. Alternatively the continuous substrate is formed from a malleable metal or metal alloy.
  • the continuous substrate is formed from a metal or metal alloy selected from copper, nickel, chromium, and stainless steel.
  • the continuous substrate is formed from copper.
  • the continuous substrate comprises at least one continuous copper wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper wires. Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical copper wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical copper wires.
  • the continuous substrate has a cross sectional diameter of about 10 to about 10,000 micrometres ( ⁇ ). Further optionally, the continuous substrate has a cross sectional diameter of about 10 to about 100 micrometres ( ⁇ ).
  • the continuous substrate comprises at least one continuous copper wire having a cross sectional diameter of about 10 to about 10000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper wires, each having a cross sectional diameter of about 10 to about 10000 micrometres ( ⁇ ). Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical copper wire having a cross sectional diameter of about 10 to about 10000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical copper wires, each having a cross sectional diameter of about 10 to about 10000 micrometres ( ⁇ ). Alternatively, the continuous substrate comprises at least one continuous copper ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper ribbons. Optionally or additionally, the continuous substrate comprises at least one continuous planar copper ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper ribbons.
  • the continuous substrate has a thickness of about 10 to about 1000 micrometres ( ⁇ ).
  • the continuous substrate comprises at least one continuous copper ribbon having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper ribbons, each having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Optionally or additionally, the continuous substrate comprises at least one continuous planar copper ribbon having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper ribbons, each having a thickness of about 10 to about 1000 micrometres ( ⁇ ).
  • the continuous substrate comprises at least one continuous copper film having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper films, each having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Optionally or additionally, the continuous substrate comprises at least one continuous planar copper film having a thickness of about 10 to about 1000 micrometres ( ⁇ ). Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper films, each having a thickness of about 10 to about 1000 micrometres ( ⁇ ).
  • wire is meant a continuous substrate having substantially the same cross sectional dimensions i.e. the dimensions on or at the polar axis are substantially the same.
  • ribbon is meant a continuous substrate having a circumferential length of greater dimension that width, and the circumferential length and the width are each greater than the thickness (depth). The width is generally less than half the dimension of the circumferential length.
  • film is meant a continuous substrate having a circumferential length of greater dimension that width, and the circumferential length and the width are each greater than the thickness (depth).
  • the width is generally greater than half the dimension of the circumferential length.
  • the step of forming graphene on or at the continuous substrate comprises providing a carbon source. Further optionally, the step of forming graphene on or at the continuous substrate comprises providing a hydrocarbon source.
  • the method comprises the steps of:
  • the providing a carbon source step comprises heating the continuous substrate. Further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature up to 1400°C. Still further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature of 800 - 1400°C. Still further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature of 800 - 1000°C.
  • the providing a carbon source step comprises heating the continuous substrate by applying a heat source. Further optionally, the providing a carbon source step comprises heating the continuous substrate by applying a heat source selected from resistive heating, combustion burners, induction heating, and plasma.
  • the providing a carbon source step comprises providing a gaseous carbon source. Further optionally or additionally, the providing a carbon source step comprises providing methane or ethylene.
  • the providing a carbon source step comprises providing a liquid carbon source. Further optionally, the providing a carbon source step comprises spraying a liquid carbon source.
  • the carbon source is an oil product. Further optionally, the carbon source is an oil distillate. Still further optionally, the carbon source is a heavy oil distillate. Still further optionally, the carbon source is an oil residuum.
  • the carbon source is a petroleum product. Further optionally, the carbon source is a petroleum distillate. Still further optionally, the carbon source is a heavy petroleum distillate. Still further optionally, the carbon source is a petroleum residuum.
  • the providing a carbon source step comprises providing petroleum jelly or paraffin wax. Further optionally or additionally, the providing a carbon source step comprises spraying petroleum jelly or paraffin wax.
  • the providing a carbon source step is conducted in the absence of a medium. Further optionally, the providing a carbon source step is conducted in the absence of a fluid medium. Still further optionally, the providing a carbon source step is conducted in the absence of air. Still further optionally, the providing a carbon source step is conducted in the absence of oxygen. Still further optionally, the providing a carbon source step is conducted under vacuum.
  • the step of forming graphene on or at the continuous substrate comprises forming a single layer of graphene on or at the continuous substrate. Further optionally, the step of forming graphene on or at the continuous substrate comprises forming more than one layer of graphene on or at the continuous substrate. Still further optionally, the step of forming graphene on or at the continuous substrate comprises forming a plurality of layers of graphene on or at the continuous substrate.
  • the step of forming graphene on or at the continuous substrate further comprises the step of removing hydrogen.
  • the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate.
  • the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate by introducing a point of discontinuity to the graphene structure. Further optionally, the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate by introducing a break, gap, opening, similar interruption, or a combination thereof to the graphene structure.
  • the removing the graphene structure step comprises irradiating the graphene structure with radiation. Further optionally, the removing the graphene structure step comprises irradiating the graphene structure with a laser. Still further optionally, the removing the graphene structure step comprises irradiating the graphene structure with a laser to introduce a point of discontinuity to the graphene structure.
  • the laser is selected from a solid-state laser, a dye laser, a gas laser, and a laser diode. Further optionally, the laser is a laser diode.
  • the laser is a red laser diode.
  • the laser is an infrared laser diode.
  • the laser is a laser diode selected from a green laser diode and a blue laser diode.
  • the laser emits light at a wavelength selected from 405 nm (InGaN blue-violet laser); 445-465 nm (InGaN blue laser multimode diode); 510-525 nm (Green diodes); 635 nm (AIGalnP red laser pointers); 650-660 nm (GalnP/AIGalnP CDDVD); 670 nm (AIGalnP bar code readers); 760 nm (AIGalnP gas sensing: 02); 785 nm (GaAIAs Compact Disc drives); 808 nm (GaAIAs pumps in DPSS Nd:YAG lasers); 848 nm (laser mice); 980 nm (InGaAs pump for optical amplifiers, for
  • Yb:YAG DPSS lasers 1 ,064 nm (AIGaAs fiber-optic communication, DPSS laser pump frequency); 1 ,310 nm (InGaAsP, InGaAsN fiber-optic communication); 1 ,480 nm (InGaAsP pump for optical amplifiers); 1 ,512 nm (InGaAsP gas sensing: NH3); 1 ,550 nm (InGaAsP, InGaAsNSb fiber-optic communication); 1 ,625 nm (InGaAsP fiber-optic communication, service channel); 1 ,654 nm (InGaAsP gas sensing: CH4); 1 ,877 nm (GalnAsSb gas sensing: H20); 2,004 nm (GalnAsSb gas sensing: C02; 2,330 nm (GalnAsSb gas sensing: CO); 2,680 nm (GalnA
  • the removing the graphene structure step comprises dissolving the continuous substrate.
  • the removing the graphene structure step comprises contacting the substrate with an acid.
  • the removing the substrate step comprises contacting the substrate with a mineral acid.
  • the removing the substrate step comprises contacting the substrate with a nitric acid.
  • the removing the substrate step comprises contacting the substrate with a fuming nitric acid.
  • the removing the graphene structure step further comprises dehydrating and/or drying the graphene structure.
  • the removing the graphene structure step further comprises degassing the graphene structure.
  • the deforming the contiguous bundle step comprises stretching the contiguous bundle. Further optionally, the deforming the contiguous bundle step comprises increasing the longitudinal length of the contiguous bundle.
  • the deforming the contiguous bundle step comprises twisting the contiguous bundle. Further optionally, the deforming the contiguous bundle step comprises rotating the contiguous bundle about the longitudinal length of the contiguous bundle. Also disclosed is an apparatus for producing graphene structures, the apparatus comprising a reaction chamber for forming graphene on or at a continuous substrate; and means for removing the graphene structure from the continuous substrate.
  • the reaction chamber comprises a heat source.
  • the reaction chamber comprises a heat source selected from a resistive heater, a combustion burner, an induction heater, and a plasma generator.
  • the reaction chamber is adapted to receive a continuous substrate. Further optionally, the reaction chamber is adapted allow the passage of a continuous substrate therethrough.
  • the reaction chamber comprises at least one aperture to allow the passage of the continuous substrate therethrough.
  • the reaction chamber comprises at least two apertures to allow the passage of the continuous substrate therethrough. Still further optionally, the reaction chamber comprises two apertures to allow the passage of the continuous substrate therethrough.
  • the reaction chamber comprises first and second apertures to allow the passage of the continuous substrate therethrough.
  • the first aperture is arranged to allow access of the continuous substrate to the reaction chamber.
  • the second aperture is arranged to allow egress of the continuous substrate from the reaction chamber.
  • the continuous substrate comprises a plurality of continuous substrates. Further optionally, the continuous substrate comprises a plurality of continuous substrates arranged about the reaction chamber. Still further optionally, the continuous substrate comprises a plurality of continuous substrates arranged radially about the reaction chamber. Still further optionally, the continuous substrate comprises a plurality of continuous substrates arranged radially about the longitudinal axis of the reaction chamber.
  • the reaction chamber is adapted to receive a carbon source. Further optionally, the reaction chamber is adapted to receive a hydrocarbon source.
  • the reaction chamber comprises a carbon source reservoir. Further optionally, the reaction chamber comprises a hydrocarbon source reservoir.
  • the reaction chamber is adapted to provide a vacuum.
  • the reaction chamber comprises a vacuum pump.
  • the means for removing the graphene structure from the continuous substrate comprises a laser.
  • the laser is selected from a solid-state laser, a dye laser, a gas laser, and a laser diode. Further optionally, the laser is a laser diode.
  • the laser is a red laser diode.
  • the laser is an infrared laser diode.
  • the laser is a laser diode selected from a green laser diode and a blue laser diode.
  • the laser emits light at a wavelength selected from 405 nm (InGaN blue-violet laser); 445-465 nm (InGaN blue laser multimode diode); 510-525 nm (Green diodes); 635 nm (AIGalnP red laser pointers); 650-660 nm (GalnP/AIGalnP CDDVD); 670 nm (AIGalnP bar code readers); 760 nm (AIGalnP gas sensing: 02); 785 nm (GaAIAs Compact Disc drives); 808 nm (GaAIAs pumps in DPSS Nd:YAG lasers); 848 nm (laser mice); 980 nm (InGaAs pump for optical amplifiers, for Yb:YAG DPSS lasers); 1 ,064 nm (AIGaAs fiber-optic communication, DPSS laser pump frequency); 1 ,310 nm (InGaAs), 4
  • the means for removing the graphene structure from the continuous substrate comprises a bath.
  • the means for removing the graphene structure from the continuous substrate comprises an acid bath.
  • the means for removing the graphene structure from the continuous substrate comprises a mineral acid bath.
  • the means for removing the graphene structure from the continuous substrate comprises a nitric acid bath.
  • the means for removing the graphene structure from the continuous substrate comprises a fuming nitric acid bath.
  • Figure 1 is a cross sectional view of a copper wire substrate having graphene formed on or at the substrate in a method according to the present invention
  • Figures 2-5 are each a schematic diagram of an apparatus for conducting a method according to the present invention
  • Figures 6 and 7 are each a schematic diagram of a preferred embodiment of an apparatus for conducting a method according to the present invention.
  • Figure 8 is a cross sectional view of graphene fibre comprising a contiguous bundle of graphene tubes in a method according to the present invention..
  • the present invention provides a method for producing graphene structures.
  • the method comprises the steps of providing a continuous substrate; forming graphene on or at the continuous substrate to provide a graphene structure; and removing the graphene structure from the continuous substrate.
  • the method of the present invention can be used for producing graphene tubes by providing a continuous generally cylindrical substrate; forming graphene on or at the continuous substrate to provide a graphene tube; and removing the graphene tube from the continuous substrate.
  • the method can be used for producing graphene fibres by providing more than one graphene tube (which can be more than one graphene tube produced by a method according to a first aspect of the present invention or any graphene tube); assembling the more than one graphene tube into a contiguous bundle; and deforming the contiguous bundle to provide a graphene fibre.
  • more than one graphene tube which can be more than one graphene tube produced by a method according to a first aspect of the present invention or any graphene tube
  • assembling the more than one graphene tube into a contiguous bundle and deforming the contiguous bundle to provide a graphene fibre.
  • the method can be used for producing graphene films by providing a continuous generally planar substrate; forming graphene on or at the continuous substrate to provide a graphene film; and removing the graphene film from the continuous substrate.
  • Continuous copper wires, or alternatively continuous (or endless) loop copper wires, each having a diameter of 10 ⁇ to 1 cm in diameter were used.
  • Other substrates may also be used instead of copper such as nickel, stainless steel, Si0 2 , Al 2 0 3 , etc.
  • the copper wire is used due to its commercial availability in a range of diameters.
  • the form factor of the substrate may be as a cylindrical wire, or a flat ribbon, or foil, or a cylindrical wire loop, or a flat ribbon loop, or foil loop, as examples.
  • the continuous copper wires, or alternatively continuous (or endless) loop copper wires are fed about rollers or tensioners, or from spools, into a reaction chamber (reactor environment) that is heated.
  • the source of heat may be any energy source that can provide reaction chamber temperatures up to 1400°C, such as resistive heating, combustion burners, induction heating, etc.
  • RF or DC plasma may also be used to provide a temperature within the plasma high enough to crack the precursor hydrocarbon.
  • a low cost hydrocarbon source is fed into the heated reaction chamber.
  • This may be a gaseous precursor such as methane or ethylene. It may also be a solid or liquid precursor such as petroleum jelly, paraffin wax, etc., that may boil and become gaseous at the reaction chamber temperature. Liquid precursor may be introduced into the reaction chamber or environment in a reservoir to generally fill the reaction chamber or environment with gaseous vapors, or may be applied directly to the substrate via a dip coating or spraying method.
  • the heat provided in the reaction chamber is sufficient to cause thermal cracking of the hydrocarbon precursor.
  • the continuous copper substrate will act as a catalyst for the thermal dissociation of the hydrocarbon precursor and carbon will deposit on the continuous substrate in the form of graphene.
  • the atmosphere within the reaction chamber can be controlled by differential pumping though multiple reactor environments so that the substrate can transition from atmospheric pressure to moderately high vacuums or slightly positive pressures. Oxygen must be eliminated from the reaction chamber or environment to prevent oxidation of the hydrocarbon into CO or C0 2 .
  • the temperature the reaction chamber and the feed rate of the continuous copper substrate will determine the form of the graphene deposited on the continuous substrate, such as monolayer graphene, or few layer graphene.
  • hydrogen gas is also produced according to the example equation: CH 4 + heat -> C + 2H 2
  • the carbon deposits on the continuous copper substrate in the form of graphene.
  • the liberated hydrogen gas can then be separated from the hydrocarbon gases within the reaction chamber by a gas separation membrane.
  • the hydrogen gas may be used as a gaseous fuel for combustion or may be further combined with nitrogen to form liquid ammonia or energy dense liquid fuels.
  • the continuous copper substrates now coated with graphene are further fed out of the reaction chamber or environment at a controlled rate.
  • the graphene structures formed on the continuous copper substrate can then be removed by laser scribing, resulting in free, continuous, hollow tubes of graphene with an inside diameter determined by the outside diameter of the continuous copper wire.
  • the operating parameters of the laser will depend in part on the material type and form of the substrate that is chosen, and may be selected by one skilled in the art.
  • the reflectivity/absorption of the laser light by the substrate will determine the laser power required to cut the graphene with minimal damage to the substrate, and may be selected by one skilled in the art.
  • the angle of incidence of the laser to the substrate can be anywhere in a range from about 90 degrees (laser beam normal to substrate surface) to an angle of approximately 45 degrees between the laser beam and the substrate surface. 405 nm wavelength (blue-violet) lasers have been proven to be effective at cutting graphene on a substrate with a minimal zone of thermal damage in the adjacent graphene.
  • the laser may also be pulsed at extremely short time intervals (for example femtoseconds) or may be a continuous wave laser.
  • the pulse duration and power settings will be adjusted to achieve cutting of graphene with minimal thermal damage to the adjacent graphene, and may be selected by one skilled in the art.
  • the laser introduces a point of discontinuity to the graphene structure, thereby providing a free end of the graphene structure e.g. a free end of the graphene structure that is no longer in contact with or adjacent to the substrate.
  • a mechanical grabber can be used to pull the free end of the graphene structure produced by the point of discontinuity introduced by the laser. This process can occur at the beginning (e.g. at the free end) of the deposited graphene structure, following which the process will be continuous e.g. the point of discontinuity will advance as the graphene structure is removed from the substrate.
  • the graphene structures Once the graphene structures have been grabbed and are pulled at a speed matching the speed of the deposition and laser cutting upstream, the graphene structures can be pulled downstream by a system of tensioning rollers and pulleys. The tension of this pulling can be low enough to avoid damage to the graphene structures, but high enough to assist in separating the graphene structure from the substrate.
  • the coefficient of thermal expansion (CTE) mismatch between the substrate and the graphene structure will aid in releasing the graphene structure from the substrate.
  • the grabber can also be rotated at a certain speed to twist the graphene structures into a multi strand, twisted graphene fibre. The rotational speed of the grabber will determine the number of twists per unit length of the graphene fibre.
  • jets of gas are blown substantially parallel to the free ends of the graphene structure to pull the graphene structure along with the gas jet, which can be a jet of air.
  • the free ends of the graphene structure can be collected (e.g. funnelled into a tube) where a mechanical grabber can pull the loose ends together and begin the twisting (yarning process) to form a graphene fibre.
  • the graphene structures formed on the continuous copper substrate can be removed by dissolution of the continuous copper substrate in an acid such as nitric acid. Resulting in free, continuous, hollow tubes of graphene with an inside diameter determined by the outside 25 diameter of the copper wire.
  • the copper wire may be left and the resulting structure is a core-shell structure with a copper core covered by a graphene shell.
  • the electrical conductivity of the graphene will result in improved conductivity of the resulting conductor wire or cable.
  • the free graphene tubes or ribbons can then be degassed via heat and vacuum.
  • the resulting plurality of free graphene tubes may now be twisted into long, continuous graphene conductors, analogous to the twisted copper conductors in conventional electrical wire or cable.
  • the graphene tubes will collapse, eliminating the inside diameter of each tube.
  • the twisted fibre may be pulled (tensioned) sufficiently that a dense conductor core is achieved.
  • the copper dissolved in acid may be recovered and reused by precipitation the copper from solution.
  • the twisted graphene fibre may then be coated with conventional polymeric insulator materials such as polyvinylchloride (PVC) or teflon, as in traditional copper wire.
  • PVC polyvinylchloride
  • teflon polyvinylchloride
  • the resulting graphene conductor wire or cable will be strong, lightweight, and can support a higher current density than traditional copper conductor wire. This will result in lower line loss due to resistance.
  • graphene conductor wires or cables could be joined by a coupler to extend the overall length to many kilometres.
  • Graphene has excellent electrical and thermal conductivity and is ideal as an electrode or conductor. Graphene is known to be able to carry the highest current density of any material at room temperature. Graphene also has excellent mechanical strength and is extremely light weight. Presently, growing large area graphene is extremely difficult. Typically, large area graphene is considered to be on the order of 50 mm x 50 mm. The limitation in growing larger area sheets of graphene is due to the limitations of the size of the chemical vapour deposition systems used for the growth of graphene and the ability to control heating rate, cooling rate, and absolute temperature. In addition, present systems are typically batch process tube furnaces.
  • the reactor environment used for graphene growth is up to a few meters in diameter, allowing the growth of extremely large area graphene.
  • the system allows for continuous processing.
  • the absolute temperature of the proposed system will be maintained due to the extremely large thermal mass and the fact that the system will be operated continuously, eliminating heat-up and cool-down cycles.
  • the heating and cooling rates of the graphene growth on the continuous copper substrate are controlled by the rate at which the substrate is moved through the reaction chamber or environment.
  • the use of differential pumping at the inlet and the outlet of the reaction chamber or environment allows for continuous feed into the reaction chamber or and can be used to control heating and cooling rates.
  • the choice of material forming the continuous substrate is critical to the design of a cost-effective and robust system.
  • the properties of the material forming the continuous substrate that have a significant impact on the final choice of material include ultimate tensile strength (UTS), elastic (Young's) modulus (E), elongation at break (a measure of ductility), coefficient of thermal expansion (CTE), melting point, and cost (both raw material cost and processing cost to produce the form, shape, and dimension of the substrate).
  • each substrate is formed in a continuous (or endless) loop and is moved in a circuit using rollers or tensioners.
  • a high ultimate tensile strength is desired. High tensile strength will allow the continuous substrate to survive the mechanical stresses that are imparted to the continuous substrate by the rollers or tensioners and by the thermal gradients from the exterior of the reaction chamber to the interior of the reaction chamber.
  • the elastic modulus of the continuous substrate should also be maximized to allow the rollers or tensioners to maintain taut tension on the continuous substrate without plastic deformation.
  • the continuous substrate will be in the order of tens to hundreds of micrometers in diameter, a high elastic modulus will be required, along with a multitude of continuous substrates in parallel on the roller or tensioner.
  • Ductility is a key characteristic in the optimal substrate material. Elongation at break is a
  • a material with high elongation at break is considered to be less prone to brittle fracture failures in service.
  • a brittle material would be prone to low cycle and high cycle fatigue failures.
  • the coefficient of thermal expansion (CTE) will be critical.
  • a high mismatch in CTE between the material forming the continuous substrate and the graphene structure will work to facilitate the release of the graphene structure from the continuous substrate.
  • a high CTE for the material forming the continuous substrate is desired.
  • a material having a high CTE will also require more adjustment of the roller or tensioner to account for the thermal expansion of the continuous substrate in the reaction chamber and to maintain a taut tension on the continuous substrate.
  • a substrate with a high melting point is desired. Temperatures commonly used for graphene deposition are on the order of 800°C to 1400°C.
  • the homologous temperature (T H ) is a ratio of the process temperature of a given system to the melting point of the material of concern.
  • the homologous temperature should always be less than 1 , and the lower T H , the better.
  • the cost of the material forming the continuous substrate impacts both capital expenditure (CAPEX) requirements and operational expenditure (OPEX) requirements.
  • CAPEX capital expenditure
  • OPEX operational expenditure
  • the CAPEX cost will be experienced in the initial assembly of the apparatus for producing graphene structures, and the OPEX cost will be experienced due to the requisite periodic replacement of the continuous substrates for preventive maintenance. Due to the thermal/mechanical stresses experienced by the continuous substrates in service, they are not expected to have an infinite lifetime. Thus the lowest cost material is desirable. However, a higher cost material may be chosen for its higher strength and resulting longer service lifetime (less frequent replacement required) such that the lifetime apparatus cost is minimized even though the one time cost is higher. While the raw material commodity cost is a strong driver for the overall cost of the continuous substrate, the processing cost for forming a given material into, for example, a micro-wire may also be significant. Thus the total cost of the continuous substrate must be considered.
  • the continuous substrate there are many candidate materials for forming the continuous substrate, from elemental metals such as copper, nickel, iron, titanium, tungsten, rhenium, and chromium; alloys such as stainless steel, constantan, Chromel®, and Alumel®; inorganics such as fused silica and basalt; composite substrates such as an iron core with a thin film shell of chromium or an iron core with a thin film shell of rhenium; and hydrocarbon substrates such as de-hydrogenated polyethylene. Copper is a common substrate used in graphene deposition.
  • suitable candidate materials such as iron, nickel, titanium, tungsten, rhenium, and chromium provide higher melting point options as compared to copper.
  • Stainless Steel 300 series or 400 series
  • constantan Chromel®
  • Alumel® all have higher strength and a higher melting point than copper.
  • Constantan, Chromel®, and Alumel® are commonly used for the production of thermocouples. As such, these alloys are currently mass produced in fine gage wire.
  • Inorganic fibers such as fused silica (Si0 2 ) and basalt have high melting points and may provide low cost material options. They are made from abundant minerals, which could be mined and processed at distributed sites and allow to local use of resources. Rhenium and chromium may serve as thin film protective layers over another bulk material to provide a core-shell composite continuous substrate. Rhenium and chromium both have very high melting points compared to copper. Both materials would also provide corrosion resistance to an underlying bulk material such as iron. Iron is a candidate material for forming continuous substrates due to its extremely low raw material cost and abundance.
  • Rhenium or chromium can be deposited on the surface of a continuous iron substrate in thin film form via sputtering and will provide a protective coating to prevent oxidation of the iron.
  • the thin film of rhenium or chromium would be on the order of 1000A thick and would also act as a diffusion barrier to prevent the diffusion of carbon from the hydrocarbon dissociation into the iron.
  • Such composite core-shell substrates of a 100 Dm diameter iron wire with a 1000-2000A sputtered coating of rhenium or chromium are expected to have very long service lifetimes, leading to overall lower OPEX.
  • Iron, copper, nickel, stainless steel, titanium, and rhenium have all been shown to be acceptable catalysts for graphene deposition.
  • Mangan, Chromel®, and Alumel® are all alloys containing copper and/or nickel. Thus, all should be acceptable catalysts for graphene deposition.
  • the inorganic substrates, silica and basalt, would likely need a thin film sputtered coating of a metallic element from the list above to act as the catalyst on the substrate.

Abstract

The present invention relates to a method for producing graphene structures, the method comprising the steps of providing a continuous substrate; forming graphene on or at the continuous substrate to provide a graphene structure; and removing the graphene structure from the continuous substrate. Also disclosed are methods for producing graphene tubes, graphene ribbons, and graphene films.

Description

Method of Producing Graphene Structures
Field of the Invention This invention relates to a method for producing graphene structures by providing a substrate; forming a graphene on or at the substrate; and removing the substrate to provide a graphene structure. Also disclosed are graphene structures produced by that method; a further method for producing graphene fibres, and the graphene fibres produced by that further method. Background to the Invention
The present invention relates to a method for producing structures formed from graphene. In particular, the present invention provides a method for producing high modulus, high tensile strength carbon fibres. High performance carbon fibres are primarily made from a polyacrylonitrile (PAN) precursor fibre that is oxidized and then carbonized. 50% of the cost of the end-product carbon fibre is attributed to the PAN precursor. 40% of the total cost of production of PAN-based carbon fibres comes from the energy intensive, high temperature oxidation and carbonization processes. The final 10% of the cost is attributed to post treatment of the fibres. Research into carbon fibres produced from other precursors such as pitch, polyolefin, and lignin have failed to produce carbon fibres with the requisite tensile strength and elastic modulus.
Further to the initial substrate cost, the process variables that have a large impact on the final cost of producing structures formed from graphene include the lifetime of the substrate in service, and the residence time of the substrate in the hot zone of the reaction chamber or during graphene deposition. In an optimized system, the substrate would have the lowest possible initial cost and the longest possible service lifetime. The residence time of the substrate in the hot zone of the reaction chamber or environment should be minimized, so as to maximize graphene production rates in terms of structure length over time, for example, by increasing the temperature of the reaction chamber or environment, thus speeding the kinetics of hydrocarbon dissociation. The kinetics of hydrocarbon dissociation can also be improved by using Le Chatellier's principle and removing product hydrogen gas from the reaction chamber or environment as it is liberated from the hydrocarbon source gas. It is also desirable to deposit the highest number of graphene layers on the substrate in the shortest possible time, so as to maximize the capture rate of graphene over a given residence time. The present invention takes advantage of the unique properties of graphene that can be produced from various cheap hydrocarbon precursors and on various substrates.
Summary of the Invention According to a first aspect of the present invention, there is provided a method for producing graphene structures, the method comprising the steps of: (a) providing a continuous substrate;
(b) forming graphene on or at the continuous substrate to provide a graphene structure; and
(c) removing the graphene structure from the continuous substrate. According to a second aspect of the present invention, there is provided a method for producing graphene tubes, the method comprising the steps of:
(a) providing a continuous generally cylindrical substrate;
(b) forming graphene on or at the continuous generally cylindrical substrate to provide a
graphene tube; and
(c) removing the graphene tube from the continuous generally cylindrical substrate.
According to a third aspect of the present invention, there is provided a method for producing graphene fibres, the method comprising the steps of:
(a) providing more than one graphene tube;
(b) assembling the more than one graphene tube into a contiguous bundle; and
(c) deforming the contiguous bundle to provide a graphene fibre.
Optionally, the providing more than one graphene tube step comprises providing more than one graphene tube produced by a method according to the first or second aspect of the present invention.
According to a fourth aspect of the present invention, there is provided a method for producing graphene films, the method comprising the steps of:
(a) providing a continuous generally planar substrate;
(b) forming graphene on or at the continuous generally planar substrate to provide a graphene film; and
(c) removing the graphene film from the continuous generally planar substrate.
By the term "continuous" is meant having no point of discontinuity, and is intended to exclude any break, gap, opening, similar interruption, or a combination thereof, to the substrate.
Optionally, the step of providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate, comprises: providing a reaction environment prior to the step of forming graphene on or at the continuous substrate. In such an embodiment, by the term "continuous" is meant a substrate having no point of discontinuity, optionally when the substrate is within the reaction environment; and is intended to exclude a substrate having any break, gap, opening, similar interruption, or a combination thereof, to the substrate, optionally when the substrate is within the reaction environment.
Optionally, the continuous substrate has no point of discontinuity. Further optionally, the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate. Still further optionally, the continuous substrate has no point of discontinuity when the substrate is within the reaction environment. Still further optionally, the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate when the substrate is within the reaction environment.
Optionally, the method comprises the steps of
(a) providing a continuous substrate, optionally a continuous generally cylindrical
substrate, optionally a continuous generally planar substrate;
(b) providing a reaction environment;
(c) forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment; and (d) removing the graphene structure from the continuous substrate.
Optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment. Further optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate through the reaction environment, prior to the step of forming graphene on or at the continuous substrate. Still further optionally, the method further comprises the step of continually passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment, prior to the step of forming graphene on or at the continuous substrate.
Optionally, the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment; forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment; and removing the graphene structure from the continuous substrate.
Optionally, the removing step is conducted outside the reaction environment. Further optionally, the removing step comprises removing the graphene structure from the continuous substrate when the substrate is outside the reaction environment.
Optionally, the reaction environment is defined by a reaction chamber.
Optionally, the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has no point of discontinuity when the substrate is within the reaction chamber. Further optionally, the continuous substrate excludes any break, gap, opening, similar interruption, or a combination thereof, to the substrate when the substrate is within the reaction chamber,
Optionally, the method comprises the steps of
(a) providing a continuous substrate optionally a continuous generally cylindrical
substrate, optionally a continuous generally planar substrate;
(b) providing a reaction chamber;
(c) forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction chamber; and
(d) removing the graphene structure from the continuous substrate.
Optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber. Further optionally, the method further comprises the step of passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate through the reaction chamber prior to the step of forming graphene on or at the continuous substrate. Still further optionally, the method further comprises the step of continually passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber prior to the step of forming graphene on or at the continuous substrate.
Optionally, the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction chamber; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction chamber;
forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction chamber; and removing the graphene structure from the continuous substrate.
Optionally, the removing step is conducted outside the reaction chamber. Further optionally, the removing step comprises removing the graphene structure from the continuous substrate when the substrate is outside the reaction chamber.
Optionally, the forming step comprises continually forming graphene on or at the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, to provide the graphene structure.
Optionally, the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; continually forming graphene on or at the continuous substrate to provide a graphene structure; and removing the graphene structure from the continuous substrate. Optionally, the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment or a reaction chamber; continually forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment or the reaction chamber; and removing the graphene structure from the continuous substrate.
Optionally, the method comprises: providing a continuous substrate, optionally a continuous generally cylindrical substrate, optionally a continuous generally planar substrate; providing a reaction environment or a reaction chamber; passing the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, through the reaction environment or the reaction chamber; forming graphene on or at the continuous substrate to provide a graphene structure, optionally when the substrate is within the reaction environment or the reaction chamber; and removing the graphene structure from the continuous substrate.
The continuous substrate can be any substrate on or at which graphene can be formed. Optionally, the continuous substrate can be any substrate on or at which graphene can be formed and from which the formed graphene structure can be removed.
Optionally, the continuous substrate is a continuous ribbon. Further optionally, the continuous substrate is a continuous planar ribbon. However, it is appreciated that the continuous ribbon can be of any cross-sectional dimension required to produce a graphene tube.
Optionally or additionally, the continuous substrate comprises at least one continuous ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous ribbons.
Optionally or additionally, the continuous substrate comprises at least one continuous planar ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar ribbons.
Optionally, the continuous substrate is a continuous plate. Further optionally, the continuous substrate is a continuous planar plate. However, it is appreciated that the continuous plate can be of any cross-sectional dimension required to produce a graphene film.
Optionally, the continuous substrate is a continuous wire. Further optionally, the continuous substrate is a continuous cylindrical wire. However, it is appreciated that the continuous wire can be of any cross-sectional shape required to produce the graphene tube.
Optionally or additionally, the continuous substrate comprises at least one continuous wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous wires. Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical wires. Optionally, the continuous substrate comprises a plurality of continuous substrates.
Optionally, the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has an uninterrupted length of more than 1 m, optionally more than 10m, further optionally more than 100m, further optionally more than 1000m.
Optionally, the continuous substrate, optionally the continuous generally cylindrical substrate, optionally the continuous generally planar substrate, has an uninterrupted length of more than 1 m within the reaction environment, optionally more than 10m within the reaction environment, further optionally more than 100m within the reaction environment, further optionally more than 1000m within the reaction environment.
Optionally, the continuous substrate forms a loop. Further optionally, the continuous substrate forms a continuous (or endless) loop. Optionally, the continuous substrate is formed from a material having an elastic modulus (E) of 75 - 463 gigapascals. Further optionally, the continuous substrate is formed from a material having an elastic modulus (E) of 75, 89, 107, 1 10, 162, 186, 189, 207, 220, 279, 407, or 463 gigapascals.
Optionally or additionally, the continuous substrate is formed from a material having an ultimate tensile strength (UTS) of 48.3 - 4840 megapascals. Further optionally or additionally, the continuous substrate is formed from a material having an ultimate tensile strength (UTS) of 48.3, 83, 220, 262, 330, 480, 552, 586, 655, 1070, or 4840 megapascals.
Optionally or additionally, the continuous substrate is formed from a material having an annealed elongation of 2 - 70%. Further optionally or additionally, the continuous substrate is formed from a material having an annealed elongation of 2, 3.15, 15, 25, 30, 35, 40, 44, 45, or 70%.
Optionally or additionally, the continuous substrate is formed from a material having a melting point of 1085 - 3400°C. Further optionally or additionally, the continuous substrate is formed from a material having a melting point of 1085, 1220, 1399, 1400, 1420, 1427, 1453, 1538, 1665, 1800, 1907, 3186, 3400°C.
Optionally or additionally, the continuous substrate is formed from a material having a density of 2.203 - 21.02 g/cm3. Further optionally or additionally, the continuous substrate is formed from a material having a density of 2.203, 2.65, 4.5, 7.14, 7.87, 8.02, 8.6, 8.73, 8.85, 8.9, 8.94, 19.3, or 21.02 g/cm3. Optionally or additionally, the continuous substrate is formed from a material having a coefficient of thermal expansion (CTE) of 0.5 - 17.3 ppm/°C. Further optionally or additionally, the continuous substrate is formed from a material having a coefficient of thermal expansion (CTE) of 0.5, 4.44, 6.2, 7.14, 8.1 , 1 1.8, 12.8, 13.7, 14.9, 16.42, 16.8, or 17.3 ppm/°C.
Optionally, the continuous substrate is formed from a material selected from copper, nickel, chromium, stainless steel, silicon dioxide, aluminium (III) oxide, iron, titanium, tungsten, rhenium, constantan, a nickel/chromium alloy such as Chromel® from Concept Alloys, Inc; a nickel, manganese, aluminium and silicon alloy such as Alumel® from Concept Alloys, Inc; basalt, polyethylene, and mixtures each thereof.
Optionally, the continuous substrate is formed from a metal or metal alloy. Further optionally, the continuous substrate is formed from a plastic metal or metal alloy. Further optionally, the continuous substrate is formed from a ductile metal or metal alloy. Alternatively the continuous substrate is formed from a malleable metal or metal alloy.
Optionally, the continuous substrate is formed from a metal or metal alloy selected from copper, nickel, chromium, and stainless steel.
Optionally, the continuous substrate is formed from copper.
Optionally or additionally, the continuous substrate comprises at least one continuous copper wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper wires. Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical copper wire. Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical copper wires.
Optionally, the continuous substrate has a cross sectional diameter of about 10 to about 10,000 micrometres (μητι). Further optionally, the continuous substrate has a cross sectional diameter of about 10 to about 100 micrometres (μητι).
Optionally or additionally, the continuous substrate comprises at least one continuous copper wire having a cross sectional diameter of about 10 to about 10000 micrometres (μητι). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper wires, each having a cross sectional diameter of about 10 to about 10000 micrometres (μιη). Optionally or additionally, the continuous substrate comprises at least one continuous cylindrical copper wire having a cross sectional diameter of about 10 to about 10000 micrometres (μιη). Further optionally or additionally, the continuous substrate comprises a plurality of continuous cylindrical copper wires, each having a cross sectional diameter of about 10 to about 10000 micrometres (μιη). Alternatively, the continuous substrate comprises at least one continuous copper ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper ribbons. Optionally or additionally, the continuous substrate comprises at least one continuous planar copper ribbon. Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper ribbons.
Optionally, the continuous substrate has a thickness of about 10 to about 1000 micrometres (μητι).
Optionally or additionally, the continuous substrate comprises at least one continuous copper ribbon having a thickness of about 10 to about 1000 micrometres (μητι). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper ribbons, each having a thickness of about 10 to about 1000 micrometres (μιη). Optionally or additionally, the continuous substrate comprises at least one continuous planar copper ribbon having a thickness of about 10 to about 1000 micrometres (μιη). Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper ribbons, each having a thickness of about 10 to about 1000 micrometres (μιη).
Alternatively, the continuous substrate comprises at least one continuous copper film having a thickness of about 10 to about 1000 micrometres (μιη). Further optionally or additionally, the continuous substrate comprises a plurality of continuous copper films, each having a thickness of about 10 to about 1000 micrometres (μιη). Optionally or additionally, the continuous substrate comprises at least one continuous planar copper film having a thickness of about 10 to about 1000 micrometres (μιη). Further optionally or additionally, the continuous substrate comprises a plurality of continuous planar copper films, each having a thickness of about 10 to about 1000 micrometres (μπη).
By "wire" is meant a continuous substrate having substantially the same cross sectional dimensions i.e. the dimensions on or at the polar axis are substantially the same. By "ribbon" is meant a continuous substrate having a circumferential length of greater dimension that width, and the circumferential length and the width are each greater than the thickness (depth). The width is generally less than half the dimension of the circumferential length.
By "film" is meant a continuous substrate having a circumferential length of greater dimension that width, and the circumferential length and the width are each greater than the thickness (depth). The width is generally greater than half the dimension of the circumferential length.
Optionally, the step of forming graphene on or at the continuous substrate comprises providing a carbon source. Further optionally, the step of forming graphene on or at the continuous substrate comprises providing a hydrocarbon source. Optionally, the method comprises the steps of:
(a) providing a continuous substrate;
(b) providing a carbon source;
(c) forming graphene on or at the continuous substrate to form a graphene structure; and (d) removing the graphene structure from the continuous substrate.
Optionally, the providing a carbon source step comprises heating the continuous substrate. Further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature up to 1400°C. Still further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature of 800 - 1400°C. Still further optionally, the providing a carbon source step comprises heating the continuous substrate to a temperature of 800 - 1000°C.
Further optionally, the providing a carbon source step comprises heating the continuous substrate by applying a heat source. Further optionally, the providing a carbon source step comprises heating the continuous substrate by applying a heat source selected from resistive heating, combustion burners, induction heating, and plasma.
Optionally or additionally, the providing a carbon source step comprises providing a gaseous carbon source. Further optionally or additionally, the providing a carbon source step comprises providing methane or ethylene.
Optionally or additionally, the providing a carbon source step comprises providing a liquid carbon source. Further optionally, the providing a carbon source step comprises spraying a liquid carbon source.
Optionally, the carbon source is an oil product. Further optionally, the carbon source is an oil distillate. Still further optionally, the carbon source is a heavy oil distillate. Still further optionally, the carbon source is an oil residuum.
Optionally, the carbon source is a petroleum product. Further optionally, the carbon source is a petroleum distillate. Still further optionally, the carbon source is a heavy petroleum distillate. Still further optionally, the carbon source is a petroleum residuum. Optionally, the providing a carbon source step comprises providing petroleum jelly or paraffin wax. Further optionally or additionally, the providing a carbon source step comprises spraying petroleum jelly or paraffin wax.
Optionally, the providing a carbon source step is conducted in the absence of a medium. Further optionally, the providing a carbon source step is conducted in the absence of a fluid medium. Still further optionally, the providing a carbon source step is conducted in the absence of air. Still further optionally, the providing a carbon source step is conducted in the absence of oxygen. Still further optionally, the providing a carbon source step is conducted under vacuum.
Optionally, the step of forming graphene on or at the continuous substrate comprises forming a single layer of graphene on or at the continuous substrate. Further optionally, the step of forming graphene on or at the continuous substrate comprises forming more than one layer of graphene on or at the continuous substrate. Still further optionally, the step of forming graphene on or at the continuous substrate comprises forming a plurality of layers of graphene on or at the continuous substrate.
Optionally, the step of forming graphene on or at the continuous substrate further comprises the step of removing hydrogen.
Optionally, the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate.
Optionally, the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate by introducing a point of discontinuity to the graphene structure. Further optionally, the removing the graphene structure step comprises releasing the graphene structure from the continuous substrate by introducing a break, gap, opening, similar interruption, or a combination thereof to the graphene structure.
Optionally, the removing the graphene structure step comprises irradiating the graphene structure with radiation. Further optionally, the removing the graphene structure step comprises irradiating the graphene structure with a laser. Still further optionally, the removing the graphene structure step comprises irradiating the graphene structure with a laser to introduce a point of discontinuity to the graphene structure.
Optionally, the laser is selected from a solid-state laser, a dye laser, a gas laser, and a laser diode. Further optionally, the laser is a laser diode.
Optionally, the laser is a red laser diode. Alternatively, the laser is an infrared laser diode.
Alternatively, the laser is a laser diode selected from a green laser diode and a blue laser diode.
Optionally, the laser emits light at a wavelength selected from 405 nm (InGaN blue-violet laser); 445-465 nm (InGaN blue laser multimode diode); 510-525 nm (Green diodes); 635 nm (AIGalnP red laser pointers); 650-660 nm (GalnP/AIGalnP CDDVD); 670 nm (AIGalnP bar code readers); 760 nm (AIGalnP gas sensing: 02); 785 nm (GaAIAs Compact Disc drives); 808 nm (GaAIAs pumps in DPSS Nd:YAG lasers); 848 nm (laser mice); 980 nm (InGaAs pump for optical amplifiers, for
Yb:YAG DPSS lasers); 1 ,064 nm (AIGaAs fiber-optic communication, DPSS laser pump frequency); 1 ,310 nm (InGaAsP, InGaAsN fiber-optic communication); 1 ,480 nm (InGaAsP pump for optical amplifiers); 1 ,512 nm (InGaAsP gas sensing: NH3); 1 ,550 nm (InGaAsP, InGaAsNSb fiber-optic communication); 1 ,625 nm (InGaAsP fiber-optic communication, service channel); 1 ,654 nm (InGaAsP gas sensing: CH4); 1 ,877 nm (GalnAsSb gas sensing: H20); 2,004 nm (GalnAsSb gas sensing: C02; 2,330 nm (GalnAsSb gas sensing: CO); 2,680 nm (GalnAsSb gas sensing: C02); 3,030 nm (GalnAsSb gas sensing: C2H2); and 3,330 nm (GalnAsSb gas sensing: CH4).
Optionally, the removing the graphene structure step comprises dissolving the continuous substrate. Optionally, the removing the graphene structure step comprises contacting the substrate with an acid. Further optionally, the removing the substrate step comprises contacting the substrate with a mineral acid. Still further optionally, the removing the substrate step comprises contacting the substrate with a nitric acid. Still further optionally, the removing the substrate step comprises contacting the substrate with a fuming nitric acid.
Optionally, the removing the graphene structure step further comprises dehydrating and/or drying the graphene structure.
Optionally or additionally, the removing the graphene structure step further comprises degassing the graphene structure.
Optionally, the deforming the contiguous bundle step comprises stretching the contiguous bundle. Further optionally, the deforming the contiguous bundle step comprises increasing the longitudinal length of the contiguous bundle.
Optionally, the deforming the contiguous bundle step comprises twisting the contiguous bundle. Further optionally, the deforming the contiguous bundle step comprises rotating the contiguous bundle about the longitudinal length of the contiguous bundle. Also disclosed is an apparatus for producing graphene structures, the apparatus comprising a reaction chamber for forming graphene on or at a continuous substrate; and means for removing the graphene structure from the continuous substrate.
Optionally, the reaction chamber comprises a heat source. Further optionally, the reaction chamber comprises a heat source selected from a resistive heater, a combustion burner, an induction heater, and a plasma generator.
Optionally, the reaction chamber is adapted to receive a continuous substrate. Further optionally, the reaction chamber is adapted allow the passage of a continuous substrate therethrough. Optionally, the reaction chamber comprises at least one aperture to allow the passage of the continuous substrate therethrough. Further optionally, the reaction chamber comprises at least two apertures to allow the passage of the continuous substrate therethrough. Still further optionally, the reaction chamber comprises two apertures to allow the passage of the continuous substrate therethrough.
Optionally, the reaction chamber comprises first and second apertures to allow the passage of the continuous substrate therethrough. Optionally, the first aperture is arranged to allow access of the continuous substrate to the reaction chamber. Optionally or additionally, the second aperture is arranged to allow egress of the continuous substrate from the reaction chamber.
Optionally, the continuous substrate comprises a plurality of continuous substrates. Further optionally, the continuous substrate comprises a plurality of continuous substrates arranged about the reaction chamber. Still further optionally, the continuous substrate comprises a plurality of continuous substrates arranged radially about the reaction chamber. Still further optionally, the continuous substrate comprises a plurality of continuous substrates arranged radially about the longitudinal axis of the reaction chamber.
Optionally, the reaction chamber is adapted to receive a carbon source. Further optionally, the reaction chamber is adapted to receive a hydrocarbon source. Optionally, the reaction chamber comprises a carbon source reservoir. Further optionally, the reaction chamber comprises a hydrocarbon source reservoir.
Optionally, the reaction chamber is adapted to provide a vacuum. Optionally, the reaction chamber comprises a vacuum pump.
Optionally, the means for removing the graphene structure from the continuous substrate comprises a laser. Optionally, the laser is selected from a solid-state laser, a dye laser, a gas laser, and a laser diode. Further optionally, the laser is a laser diode.
Optionally, the laser is a red laser diode. Alternatively, the laser is an infrared laser diode. Alternatively, the laser is a laser diode selected from a green laser diode and a blue laser diode.
Optionally, the laser emits light at a wavelength selected from 405 nm (InGaN blue-violet laser); 445-465 nm (InGaN blue laser multimode diode); 510-525 nm (Green diodes); 635 nm (AIGalnP red laser pointers); 650-660 nm (GalnP/AIGalnP CDDVD); 670 nm (AIGalnP bar code readers); 760 nm (AIGalnP gas sensing: 02); 785 nm (GaAIAs Compact Disc drives); 808 nm (GaAIAs pumps in DPSS Nd:YAG lasers); 848 nm (laser mice); 980 nm (InGaAs pump for optical amplifiers, for Yb:YAG DPSS lasers); 1 ,064 nm (AIGaAs fiber-optic communication, DPSS laser pump frequency); 1 ,310 nm (InGaAsP, InGaAsN fiber-optic communication); 1 ,480 nm (InGaAsP pump for optical amplifiers); 1 ,512 nm (InGaAsP gas sensing: NH3); 1 ,550 nm (InGaAsP, InGaAsNSb fiber-optic communication); 1 ,625 nm (InGaAsP fiber-optic communication, service channel); 1 ,654 nm (InGaAsP gas sensing: CH4); 1 ,877 nm (GalnAsSb gas sensing: H20); 2,004 nm (GalnAsSb gas sensing: C02; 2,330 nm (GalnAsSb gas sensing: CO); 2,680 nm (GalnAsSb gas sensing: C02); 3,030 nm (GalnAsSb gas sensing: C2H2); and 3,330 nm (GalnAsSb gas sensing: CH4).
Optionally, the means for removing the graphene structure from the continuous substrate comprises a bath. Optionally, the means for removing the graphene structure from the continuous substrate comprises an acid bath. Further optionally, the means for removing the graphene structure from the continuous substrate comprises a mineral acid bath. Still further optionally, the means for removing the graphene structure from the continuous substrate comprises a nitric acid bath. Still further optionally, the means for removing the graphene structure from the continuous substrate comprises a fuming nitric acid bath.
Brief Description of the Drawings
Embodiments of the present invention will now be described with reference to the accompanying drawings and non-limiting examples, in which:
Figure 1 is a cross sectional view of a copper wire substrate having graphene formed on or at the substrate in a method according to the present invention; Figures 2-5 are each a schematic diagram of an apparatus for conducting a method according to the present invention;
Figures 6 and 7 are each a schematic diagram of a preferred embodiment of an apparatus for conducting a method according to the present invention; and
Figure 8 is a cross sectional view of graphene fibre comprising a contiguous bundle of graphene tubes in a method according to the present invention..
Detailed Description of the Invention
The present invention provides a method for producing graphene structures. The method comprises the steps of providing a continuous substrate; forming graphene on or at the continuous substrate to provide a graphene structure; and removing the graphene structure from the continuous substrate. The method of the present invention can be used for producing graphene tubes by providing a continuous generally cylindrical substrate; forming graphene on or at the continuous substrate to provide a graphene tube; and removing the graphene tube from the continuous substrate. Moreover, the method can be used for producing graphene fibres by providing more than one graphene tube (which can be more than one graphene tube produced by a method according to a first aspect of the present invention or any graphene tube); assembling the more than one graphene tube into a contiguous bundle; and deforming the contiguous bundle to provide a graphene fibre.
The method can be used for producing graphene films by providing a continuous generally planar substrate; forming graphene on or at the continuous substrate to provide a graphene film; and removing the graphene film from the continuous substrate.
Producing graphene fibres
Continuous copper wires, or alternatively continuous (or endless) loop copper wires, each having a diameter of 10 μιτι to 1 cm in diameter were used. Other substrates may also be used instead of copper such as nickel, stainless steel, Si02, Al203, etc. The copper wire is used due to its commercial availability in a range of diameters. The form factor of the substrate may be as a cylindrical wire, or a flat ribbon, or foil, or a cylindrical wire loop, or a flat ribbon loop, or foil loop, as examples. The continuous copper wires, or alternatively continuous (or endless) loop copper wires are fed about rollers or tensioners, or from spools, into a reaction chamber (reactor environment) that is heated. The source of heat may be any energy source that can provide reaction chamber temperatures up to 1400°C, such as resistive heating, combustion burners, induction heating, etc. RF or DC plasma may also be used to provide a temperature within the plasma high enough to crack the precursor hydrocarbon.
A low cost hydrocarbon source is fed into the heated reaction chamber. This may be a gaseous precursor such as methane or ethylene. It may also be a solid or liquid precursor such as petroleum jelly, paraffin wax, etc., that may boil and become gaseous at the reaction chamber temperature. Liquid precursor may be introduced into the reaction chamber or environment in a reservoir to generally fill the reaction chamber or environment with gaseous vapors, or may be applied directly to the substrate via a dip coating or spraying method.
The heat provided in the reaction chamber is sufficient to cause thermal cracking of the hydrocarbon precursor. The continuous copper substrate will act as a catalyst for the thermal dissociation of the hydrocarbon precursor and carbon will deposit on the continuous substrate in the form of graphene.
The atmosphere within the reaction chamber can be controlled by differential pumping though multiple reactor environments so that the substrate can transition from atmospheric pressure to moderately high vacuums or slightly positive pressures. Oxygen must be eliminated from the reaction chamber or environment to prevent oxidation of the hydrocarbon into CO or C02. The temperature the reaction chamber and the feed rate of the continuous copper substrate (so time and temperature) will determine the form of the graphene deposited on the continuous substrate, such as monolayer graphene, or few layer graphene. Upon thermal dissociation of the hydrocarbon, hydrogen gas is also produced according to the example equation: CH4 + heat -> C + 2H2
In this example, the carbon deposits on the continuous copper substrate in the form of graphene. The liberated hydrogen gas can then be separated from the hydrocarbon gases within the reaction chamber by a gas separation membrane. The hydrogen gas may be used as a gaseous fuel for combustion or may be further combined with nitrogen to form liquid ammonia or energy dense liquid fuels. The continuous copper substrates now coated with graphene are further fed out of the reaction chamber or environment at a controlled rate. The graphene structures formed on the continuous copper substrate can then be removed by laser scribing, resulting in free, continuous, hollow tubes of graphene with an inside diameter determined by the outside diameter of the continuous copper wire.
The operating parameters of the laser will depend in part on the material type and form of the substrate that is chosen, and may be selected by one skilled in the art. The reflectivity/absorption of the laser light by the substrate will determine the laser power required to cut the graphene with minimal damage to the substrate, and may be selected by one skilled in the art. The angle of incidence of the laser to the substrate can be anywhere in a range from about 90 degrees (laser beam normal to substrate surface) to an angle of approximately 45 degrees between the laser beam and the substrate surface. 405 nm wavelength (blue-violet) lasers have been proven to be effective at cutting graphene on a substrate with a minimal zone of thermal damage in the adjacent graphene. Flowing an inert gas such as argon across the surface of the substrate in the path of the laser beam helps to remove debris and carbon vapor from the laser cutting zone. The laser may also be pulsed at extremely short time intervals (for example femtoseconds) or may be a continuous wave laser. The pulse duration and power settings will be adjusted to achieve cutting of graphene with minimal thermal damage to the adjacent graphene, and may be selected by one skilled in the art. The laser introduces a point of discontinuity to the graphene structure, thereby providing a free end of the graphene structure e.g. a free end of the graphene structure that is no longer in contact with or adjacent to the substrate. A mechanical grabber can be used to pull the free end of the graphene structure produced by the point of discontinuity introduced by the laser. This process can occur at the beginning (e.g. at the free end) of the deposited graphene structure, following which the process will be continuous e.g. the point of discontinuity will advance as the graphene structure is removed from the substrate. Once the graphene structures have been grabbed and are pulled at a speed matching the speed of the deposition and laser cutting upstream, the graphene structures can be pulled downstream by a system of tensioning rollers and pulleys. The tension of this pulling can be low enough to avoid damage to the graphene structures, but high enough to assist in separating the graphene structure from the substrate. The coefficient of thermal expansion (CTE) mismatch between the substrate and the graphene structure will aid in releasing the graphene structure from the substrate. As the mechanical grabber is used to apply tension to pull the graphene structure downstream, the grabber can also be rotated at a certain speed to twist the graphene structures into a multi strand, twisted graphene fibre. The rotational speed of the grabber will determine the number of twists per unit length of the graphene fibre.
In an alternative embodiment, jets of gas are blown substantially parallel to the free ends of the graphene structure to pull the graphene structure along with the gas jet, which can be a jet of air. The free ends of the graphene structure can be collected (e.g. funnelled into a tube) where a mechanical grabber can pull the loose ends together and begin the twisting (yarning process) to form a graphene fibre.
Alternatively, the graphene structures formed on the continuous copper substrate can be removed by dissolution of the continuous copper substrate in an acid such as nitric acid. Resulting in free, continuous, hollow tubes of graphene with an inside diameter determined by the outside 25 diameter of the copper wire.
Alternatively, the copper wire may be left and the resulting structure is a core-shell structure with a copper core covered by a graphene shell. The electrical conductivity of the graphene will result in improved conductivity of the resulting conductor wire or cable.
The free graphene tubes or ribbons can then be degassed via heat and vacuum.
As the continuous copper wires or substrates may be fed into the reaction chamber or environment as a plurality, the resulting plurality of free graphene tubes may now be twisted into long, continuous graphene conductors, analogous to the twisted copper conductors in conventional electrical wire or cable. As the fibre is twisted, the graphene tubes will collapse, eliminating the inside diameter of each tube. The twisted fibre may be pulled (tensioned) sufficiently that a dense conductor core is achieved. The copper dissolved in acid may be recovered and reused by precipitation the copper from solution.
The twisted graphene fibre may then be coated with conventional polymeric insulator materials such as polyvinylchloride (PVC) or teflon, as in traditional copper wire. The resulting graphene conductor wire or cable will be strong, lightweight, and can support a higher current density than traditional copper conductor wire. This will result in lower line loss due to resistance. For long transmission lines, graphene conductor wires or cables could be joined by a coupler to extend the overall length to many kilometres.
Producing graphene films
Using the same method previously described for depositing graphene on copper wires in a continuous process, large area (>1 m wide by >1 km long) thin films of graphene may be produced. A copper plate with any thickness between 10 μιτι to several mm and length of >1 kilometre can be used.
Graphene has excellent electrical and thermal conductivity and is ideal as an electrode or conductor. Graphene is known to be able to carry the highest current density of any material at room temperature. Graphene also has excellent mechanical strength and is extremely light weight. Presently, growing large area graphene is extremely difficult. Typically, large area graphene is considered to be on the order of 50 mm x 50 mm. The limitation in growing larger area sheets of graphene is due to the limitations of the size of the chemical vapour deposition systems used for the growth of graphene and the ability to control heating rate, cooling rate, and absolute temperature. In addition, present systems are typically batch process tube furnaces. In the present methods, the reactor environment used for graphene growth is up to a few meters in diameter, allowing the growth of extremely large area graphene. In addition, as described in previous embodiments, the system allows for continuous processing. The absolute temperature of the proposed system will be maintained due to the extremely large thermal mass and the fact that the system will be operated continuously, eliminating heat-up and cool-down cycles. The heating and cooling rates of the graphene growth on the continuous copper substrate are controlled by the rate at which the substrate is moved through the reaction chamber or environment. The use of differential pumping at the inlet and the outlet of the reaction chamber or environment allows for continuous feed into the reaction chamber or and can be used to control heating and cooling rates. The choice of material forming the continuous substrate is critical to the design of a cost-effective and robust system. The properties of the material forming the continuous substrate that have a significant impact on the final choice of material include ultimate tensile strength (UTS), elastic (Young's) modulus (E), elongation at break (a measure of ductility), coefficient of thermal expansion (CTE), melting point, and cost (both raw material cost and processing cost to produce the form, shape, and dimension of the substrate).
In a preferred embodiment, each substrate is formed in a continuous (or endless) loop and is moved in a circuit using rollers or tensioners. In order to maximize the lifetime of the continuous substrates, a high ultimate tensile strength is desired. High tensile strength will allow the continuous substrate to survive the mechanical stresses that are imparted to the continuous substrate by the rollers or tensioners and by the thermal gradients from the exterior of the reaction chamber to the interior of the reaction chamber.
The elastic modulus of the continuous substrate should also be maximized to allow the rollers or tensioners to maintain taut tension on the continuous substrate without plastic deformation. As the continuous substrate will be in the order of tens to hundreds of micrometers in diameter, a high elastic modulus will be required, along with a multitude of continuous substrates in parallel on the roller or tensioner. Ductility is a key characteristic in the optimal substrate material. Elongation at break is a
characteristic that gives an indication of ductility during a tensile test. A material with high elongation at break is considered to be less prone to brittle fracture failures in service. As the continuous substrate will be wound around the relatively tight radius of the roller or tensioner, a brittle material would be prone to low cycle and high cycle fatigue failures.
Once the graphene structure has been deposited on the substrate and is being released from the substrate outside of the reaction chamber, the coefficient of thermal expansion (CTE) will be critical. A high mismatch in CTE between the material forming the continuous substrate and the graphene structure will work to facilitate the release of the graphene structure from the continuous substrate. Here, a high CTE for the material forming the continuous substrate is desired. However, a material having a high CTE will also require more adjustment of the roller or tensioner to account for the thermal expansion of the continuous substrate in the reaction chamber and to maintain a taut tension on the continuous substrate. A substrate with a high melting point is desired. Temperatures commonly used for graphene deposition are on the order of 800°C to 1400°C. Obviously, the melting point of the material forming the continuous substrate must be higher than the process temperature, to prevent melting of the substrate. The homologous temperature (TH) is a ratio of the process temperature of a given system to the melting point of the material of concern. The homologous temperature should always be less than 1 , and the lower TH, the better.
The cost of the material forming the continuous substrate impacts both capital expenditure (CAPEX) requirements and operational expenditure (OPEX) requirements. The CAPEX cost will be experienced in the initial assembly of the apparatus for producing graphene structures, and the OPEX cost will be experienced due to the requisite periodic replacement of the continuous substrates for preventive maintenance. Due to the thermal/mechanical stresses experienced by the continuous substrates in service, they are not expected to have an infinite lifetime. Thus the lowest cost material is desirable. However, a higher cost material may be chosen for its higher strength and resulting longer service lifetime (less frequent replacement required) such that the lifetime apparatus cost is minimized even though the one time cost is higher. While the raw material commodity cost is a strong driver for the overall cost of the continuous substrate, the processing cost for forming a given material into, for example, a micro-wire may also be significant. Thus the total cost of the continuous substrate must be considered.
There are many candidate materials for forming the continuous substrate, from elemental metals such as copper, nickel, iron, titanium, tungsten, rhenium, and chromium; alloys such as stainless steel, constantan, Chromel®, and Alumel®; inorganics such as fused silica and basalt; composite substrates such as an iron core with a thin film shell of chromium or an iron core with a thin film shell of rhenium; and hydrocarbon substrates such as de-hydrogenated polyethylene. Copper is a common substrate used in graphene deposition.
Other suitable candidate materials such as iron, nickel, titanium, tungsten, rhenium, and chromium provide higher melting point options as compared to copper. Several alloys would provide a good combination of thermomechanical properties and cost as candidate materials. Stainless Steel (300 series or 400 series), constantan, Chromel®, and Alumel® all have higher strength and a higher melting point than copper. Constantan, Chromel®, and Alumel® are commonly used for the production of thermocouples. As such, these alloys are currently mass produced in fine gage wire.
Inorganic fibers such as fused silica (Si02) and basalt have high melting points and may provide low cost material options. They are made from abundant minerals, which could be mined and processed at distributed sites and allow to local use of resources. Rhenium and chromium may serve as thin film protective layers over another bulk material to provide a core-shell composite continuous substrate. Rhenium and chromium both have very high melting points compared to copper. Both materials would also provide corrosion resistance to an underlying bulk material such as iron. Iron is a candidate material for forming continuous substrates due to its extremely low raw material cost and abundance. Rhenium or chromium can be deposited on the surface of a continuous iron substrate in thin film form via sputtering and will provide a protective coating to prevent oxidation of the iron. The thin film of rhenium or chromium would be on the order of 1000A thick and would also act as a diffusion barrier to prevent the diffusion of carbon from the hydrocarbon dissociation into the iron. Such composite core-shell substrates of a 100 Dm diameter iron wire with a 1000-2000A sputtered coating of rhenium or chromium are expected to have very long service lifetimes, leading to overall lower OPEX.
Iron, copper, nickel, stainless steel, titanium, and rhenium have all been shown to be acceptable catalysts for graphene deposition. Constantan, Chromel®, and Alumel® are all alloys containing copper and/or nickel. Thus, all should be acceptable catalysts for graphene deposition. The inorganic substrates, silica and basalt, would likely need a thin film sputtered coating of a metallic element from the list above to act as the catalyst on the substrate.

Claims

Claims
1. A method for producing graphene structures, the method comprising the steps of:
(a) providing a continuous substrate;
(b) forming graphene on or at the continuous substrate to provide a graphene structure; and
(c) removing the graphene structure from the continuous substrate.
2. A method according to Claim 1 , wherein the step of providing a continuous substrate
comprises: providing a reaction environment prior to the step of forming graphene on or at the continuous substrate.
A method according to Claim 2 further comprising the step of passing the continuous substrate through the reaction environment prior to the step of forming graphene on or at the continuous substrate.
A method according to Claim 2 or 3, wherein the step of forming graphene on or at the continuous substrate comprises forming graphene on or at the continuous substrate when the substrate is within the reaction environment.
A method according to any one of Claims 2-4, wherein the removing step comprises removing the graphene structure from the continuous substrate when the substrate is outside the reaction environment.
6. A method according to any one of Claims 1-5, wherein the step of forming graphene on or at the continuous substrate comprises continually forming graphene on or at the continuous substrate.
7. A method according to any one of Claims 1-6, wherein the continuous substrate comprises a plurality of continuous substrates.
8. A method according to any one of Claims 1-7, wherein the or each continuous substrate has an uninterrupted length of more than 1 m.
9. A method according to any one of Claims 1-8, wherein the or each continuous substrate forms a loop.
10. A method according to any one of Claims 1-9, wherein the or each continuous substrate is formed from a metal or metal alloy selected from copper, nickel, chromium, and stainless steel.
1 1. A method according to any one of Claims 1-10, wherein the step of forming graphene on or at the continuous substrate comprises providing a carbon source under vacuum and heating the continuous substrate to a temperature up to 1400°C.
A method according to any one of Claims 1-1 1 , wherein the removing the graphene structure step comprises irradiating the graphene structure with a laser selected from a solid-state laser, a dye laser, a gas laser, and a laser diode to introduce a point of discontinuity to the graphene structure.
A method according to any one of Claims 1-1 1 , wherein the removing the graphene structure step comprises contacting the substrate with a mineral acid.
14. An apparatus for producing graphene structures, the apparatus comprising a reaction
chamber for forming graphene on or at a continuous substrate; and means for removing the graphene structure from the continuous substrate, wherein the reaction chamber is adapted allow the passage of the continuous substrate therethrough.
15. An apparatus according to Claim 14 further comprising a plurality of continuous substrates arranged radially about the longitudinal axis of the reaction chamber.
16. A method for producing graphene tubes, the method comprising the steps of:
(a) providing a continuous generally cylindrical substrate;
(b) forming graphene on or at the continuous generally cylindrical substrate to provide a graphene tube; and
(c) removing the graphene tube from the continuous generally cylindrical substrate.
17. A method for producing graphene fibres, the method comprising the steps of:
(a) providing more than one graphene tube produced by a method according to
16;
(b) assembling the more than one graphene tube into a contiguous bundle; and
(c) deforming the contiguous bundle to provide a graphene fibre.
PCT/EP2016/073525 2015-10-02 2016-09-30 Method of producing graphene structures WO2017055618A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2458776A (en) * 2008-03-31 2009-10-07 Qinetiq Ltd Chemical vapour deposition process
US20120128573A1 (en) * 2010-11-19 2012-05-24 Research & Business Foundation Sungkyunkwan University Method for fabricating three dimensional graphene structures using catalyst templates
US20130220530A1 (en) * 2012-02-24 2013-08-29 Kuanping Gong Method of transferring graphene
CN103435035A (en) * 2013-08-20 2013-12-11 常州二维碳素科技有限公司 Device and method for continuous preparing and transferring graphene

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2458776A (en) * 2008-03-31 2009-10-07 Qinetiq Ltd Chemical vapour deposition process
US20120128573A1 (en) * 2010-11-19 2012-05-24 Research & Business Foundation Sungkyunkwan University Method for fabricating three dimensional graphene structures using catalyst templates
US20130220530A1 (en) * 2012-02-24 2013-08-29 Kuanping Gong Method of transferring graphene
CN103435035A (en) * 2013-08-20 2013-12-11 常州二维碳素科技有限公司 Device and method for continuous preparing and transferring graphene

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
GOLAP KALITA ET AL: "Synthesis of continuous graphene on metal foil for flexible transparent electrode application", NANOELECTRONICS CONFERENCE (INEC), 2013 IEEE 5TH INTERNATIONAL, IEEE, vol. 1,4-10,12-147, 2 January 2013 (2013-01-02), pages 281 - 284, XP032334290, ISBN: 978-1-4673-4840-9, DOI: 10.1109/INEC.2013.6466023 *
HESJEDAL THORSTEN: "Continuous roll-to-roll growth of graphene films by chemical vapor deposition", APPLIED PHYSICS LETTERS, AMERICAN INSTITUTE OF PHYSICS, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747, vol. 98, no. 13, 30 March 2011 (2011-03-30), pages 133106 - 133106, XP012139930, ISSN: 0003-6951, DOI: 10.1063/1.3573866 *
X. LI ET AL: "Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils", SCIENCE, vol. 324, no. 5932, 7 May 2009 (2009-05-07), US, pages 1312 - 1314, XP055259738, ISSN: 0036-8075, DOI: 10.1126/science.1171245 *
XUESONG LI ET AL: "Large-area synthesis of high-quality and uniform graphene films on copper foils", SCIENCE, AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE, US, vol. 324, no. 5932, 5 June 2009 (2009-06-05), pages 1312 - 1314, XP008127472, ISSN: 0036-8075, [retrieved on 20090507], DOI: 10.1126/SCIENCE.1171245 *

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