WO2012167703A1

WO2012167703A1 - Method for preparing graphene by high temperature atom dialysis based on chemical vapor deposition

Info

Publication number: WO2012167703A1
Application number: PCT/CN2012/076201
Authority: WO
Inventors: 瞿研
Original assignee: 无锡第六元素高科技发展有限公司
Priority date: 2011-06-09
Filing date: 2012-05-29
Publication date: 2012-12-13
Also published as: CN102275907B; CN102275907A

Abstract

The present invention relates to a method for preparing graphene by high temperature atom dialysis based on chemical vapor deposition. The method comprises depositing carbon source gas on a pocket-shaped metal substrate in reductive atmosphere by means of gradually cooling it down from high temperature, and thus obtaining a monolayer and/or multilayer grahpene deposited inside the pocket-shaped metal substrate. The reductive atmosphere is hydrogen atmosphere. The grahpene is superior in crystal quality, the crystal size (domain) can be up to 500μm and the grahpene has excellent transparence; and the thickness can be controllable from monolayer to multilayer.

Description

Method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition

Technical field

The invention relates to the technical field of preparation of graphene materials, in particular to a method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition.

Background technique

Graphene, the English name Graphene, is a two-dimensional lattice structure in which carbon atoms are arranged in hexagons. As a single-layer carbon atom planar material, graphene can be obtained by peeling off a graphite material. Since the graphite crystal film was discovered by scientists at the University of Manchester in 2004, graphene has become the focus of attention in the scientific and industrial circles. Graphene has a thickness of only 0.335 nm, which is not only the thinnest of the known materials, but also very strong and hard. As a simple substance, it transmits electrons at room temperature faster than all known conductors and semiconductors (graphene The migration speed of electrons reaches 1/300 of the speed of light). Due to the special atomic structure of graphene, the behavior of carriers (electrons and holes) must be characterized by Relativistic Quantum Mechanics. Due to its high electron mobility and high light transmittance, graphene may be used in various information technology fields, for example, as a transparent conductive electrode for flat panel displays, or as a channel layer for high frequency/RF transistors. Meanwhile, as a single layer structure of carbon atoms, the theoretical specific surface area of up graphene 2630m ² / g. Such a high specific surface area makes the graphene-based material a promising energy storage active material, making it possible to use graphene materials in hydrogen storage, new lithium ion batteries, supercapacitors or fuel cells.

There are several ways to prepare this special material:

1. Slight rubbing or tearing tape method (paste HOPG (highly oriented pyrolytic graphite))

This method is simple and easy to obtain high quality graphene. But the yield is extremely low, in a piece of Si Usually only a few micrometers of graphene are obtained on the substrate. Therefore, this method is only suitable for the preparation of graphene in the laboratory, and is not suitable for industrial mass production.

2. Heating SiC method

In this method, Si is removed by heating single crystal 6H-SiC, and a graphene sheet is decomposed on the single crystal (0001) plane. The specific process is as follows: A sample obtained by etching with oxygen or hydrogen is heated by electron bombardment under high vacuum to remove oxides. After the Auchen electron spectroscopy is used to confirm that the oxide on the surface is completely removed, the sample is heated to raise the temperature to 1250-1450 ° C and then thermostated for 1 minute to 20 minutes to form a very thin graphite layer. Exploration, Berger et al. have been able to controllably prepare single or multi-layer graphene. Since the thickness is determined by the heating temperature, it is difficult to prepare a graphene having a single thickness in a large area.

The method can realize large-size, high-quality graphene preparation, and is a preparation method which is very important for realizing the practical application of the graphene device. The disadvantage is that SiC is too expensive, and the obtained graphene is difficult to transfer to other substrates.

3. Chemical dispersion method

Graphite oxide is formed by the hydrolysis of graphite under the action of strong oxidants such as H ₂ S0 ₄ , HN0 ₃ , HC10 ₄ or by electrochemical peroxidation. Graphite oxide is also a layered covalent compound with a interlayer distance of about 0.8 nm (graphite is 0.335 nm), which varies depending on the preparation method. It is considered that the graphite oxide contains a group such as -C-OH, -C-0-C, or even -COOH. Unlike graphite, the graphite oxide sheet has a strong hydrophilic or polar solvent property due to the presence of polar groups. Therefore, the graphite oxide can be peeled off in water or other polar solvent by external force, such as ultrasonic waves, to form a single layer of graphene oxide (Graphene Oxide) ₀ to obtain graphene oxide, and then to be oxidized by chemical reduction. Graphene is de- graphitized by deoxidation, and its conductivity can be restored when its geometry is maintained.

The method dissociates natural graphite powder into a single layer of graphite during oxidation and reduction. Although it only partially reduces its conductivity during the redox process (destroying the high electron mobility of graphene itself), The product has a relatively high powder specific surface area (>700 m ² /g) and the process is relatively simple, so the method is more suitable for industrial large-scale production of graphene materials. However, it is only partially reduced in conductivity during the redox process (destroying the high electron mobility of the graphene itself).

4, chemical vapor deposition (CVD, Chemical Vapor Deposition)

A carbonaceous compound such as methane is used as a carbon source to grow graphene by pyrolysis on the surface of the substrate. Ren Wencai gave the growth mechanism of graphene in CVD method in "Preparation of Graphene by Chemical Vapor Deposition": (1) Mechanism of Carburizing and Carbon Deposition: For metal matrix with high carbon content such as nickel, carbon The carbon atoms generated by the source cracking penetrate into the metal body at a high temperature, and then nucleate out from the inside when the temperature is lowered, and then grow into graphene; (2) Surface growth mechanism: a metal matrix having a lower carbon content such as copper The carbon atoms generated by the cracking of the gaseous carbon source at high temperature are adsorbed on the surface of the metal, and then nucleated to form a "graphene island", and a two-dimensional growth of the "graphene island" is combined to obtain a continuous graphene film. (Preparation of Graphene by Chemical Vapor Deposition, Ren Wencai et al., New Carbon Materials, 2011, February, Vol. 26, No. 1) CN101285175 discloses a method for preparing graphene. The method comprises the steps of preparing a graphene by chemical vapor deposition, comprising the steps of: placing a substrate with a catalyst in an oxygen-free reactor, bringing the temperature of the substrate to 500-1200 ° C, and then reacting to the reaction. A carbonaceous material is introduced into the apparatus to obtain graphene; wherein the catalyst is a metal or a metal compound. The method for preparing graphene according to the invention requires that a catalyst be deposited on the substrate first, and the catalyst needs to be removed again after the graphene is deposited, which is cumbersome.

How to develop a graphene with simple preparation method, easy control, low defect, good light transmittance, large size and single thickness controllable is a technical problem in the art.

Summary of the invention

In view of the deficiencies of the prior art, it is an object of the present invention to provide a method of preparing a super-large area thickness controllable single or multi-layer graphene film. The method is based on high temperature of chemical vapor deposition A method of preparing graphene by atomic dialysis, wherein the high temperature in the high temperature atomic dialysis refers to a temperature of 800 °C.

The present invention is achieved by the following technical solution: In a reducing atmosphere, a carbon source gas is deposited on a charge-like metal substrate by gradually decreasing the temperature from a high temperature, thereby obtaining a single layer deposited on the inner side of the charge-like metal substrate and/or Or multilayer graphene; the reducing atmosphere is a hydrogen atmosphere.

The invention is based on a chemical vapor deposition method for pyrolyzing formazan or other hydrocarbon gas on the outer surface of a closed charge-like metal substrate, and the deposited carbon atoms are dialyzed to the inner surface of the metal substrate at a high temperature to form graphite on the inner surface. Alkene film. In this method, graphene is formed at a slower rate, and the formed graphene grains are larger, thereby providing a method for preparing an ultra-large grain graphene film.

The method for preparing the charge-like metal substrate is as follows: taking a rectangular metal substrate, after folding, the three sides of the opening are sealed to form a pouch-like copper foil. The "sealing the three sides of the opening" is a technique well known to those skilled in the art, and typical but non-limiting examples are compression. The size of the rectangular metal substrate is not particularly limited, and those skilled in the art can rectangular metal substrate according to the actual length and width are selected, the present invention is preferably from 50-150mm ^2, more preferably from 80-120mm ^2.

In the present invention, the choice of the metal substrate determines the dialysis rate of the graphene, the dialysis temperature, the growth temperature, the growth substrate, and the type of carbon source gas used. At the same time, the crystal type and crystal orientation of the metal also affect the growth of graphene. quality. The present invention selects the metal substrate after considering factors such as the melting point of the metal, the amount of carbon dissolved, and whether or not there is a stable metal carbide.

Preferably, the metal in the metal substrate of the present invention is selected from any one or a combination of at least two of nickel, copper, ruthenium, cobalt, palladium, platinum, rhodium or ruthenium, such as foil, nickel foil, palladium metal. The foil, the cobalt-palladium alloy foil, the copper-rhenium-tellurium alloy foil, or the like is preferably any one of copper foil, nickel foil, nickel-copper alloy foil, copper-bismuth-nickel alloy foil, and copper-cobalt alloy foil. The combination of the two types is more preferably any one or a combination of at least two of copper foil, nickel foil or nickel-copper alloy foil.

The prior art shows that CVD growth of graphene mainly involves three aspects: carbon source, growth substrate (lining) Bottom) and growth conditions (barometric pressure, carrier, temperature, etc.). (Preparation of Graphene by Chemical Vapor Deposition, Ren Wencai et al., New Carbon Materials, February 2011, Vol. 26, No. 1)

In the present invention, the carbon source is a gaseous carbon source. Preferably, the carbon source gas of the present invention is an organic gas containing only carbon atoms and hydrogen atoms, and any one known to those skilled in the art contains only one. The gas of the H element may be used in the present invention, and the present invention preferably has any one or a combination of at least two of a C1-C4 terpene hydrocarbon, a C2-C4 olefin, and a C2-C3 alkyne, wherein C1-C4 Examples of the alkane are methane, ethyl hydrazine, propidium, cyclopropane, n-butane, isobutyl hydrazine, methylcyclopropene or cyclobutyl hydrazine; and examples of the C2-C4 olefin are ethylene, propylene, n-butene , isobutylene, 1,3-butadiene, 1,2-butadiene, etc.; examples of the C2-C3 alkyne are acetylene, propyne, 1-butyne, 2-butyne, etc., such as a combination浣/acetamidine, acetylene/1,2-butadiene/n-butylene, propyne/propane, n-butylene/1,3-butadiene/2-butyne, and the like.

In the process of preparing graphene by chemical vapor deposition, the choice of carbon source largely determines the growth temperature of graphene. The present invention considers the decomposition temperature, decomposition rate and decomposition product of the carbon source gas, and further Preferred are methane, ethane, ethylene, acetylene, propionium, n-butene, isobutylene, 1,2-butadiene, 1,3-butadiene, cis-butadiene, anti-butadiene, n-butane, and As a carbon source gas of the present invention, any one or a combination of at least two of butyl hydrazine, propylene, and propylene is preferable as the carbon source gas of the present invention.

As a preferred technical solution, the method for preparing single-layer or multi-layer graphene based on chemical vapor deposition high temperature sub-dialysis of the present invention comprises the following steps:

(1) preparing a charge-like metal substrate;

(2) placing a charge-like metal substrate in a vacuum reactor;

(3) removing oxygen from the vacuum chamber;

(4) injecting a reducing gas into the vacuum chamber;

(5) heating up; (6) injecting a carbon source gas into the vacuum chamber while maintaining a reducing gas flow rate;

(7) cooling, a metal substrate on which graphene is deposited;

(8) Take out the metal substrate on which graphene is deposited.

Preferably, the preparing the clad metal substrate as described in the step (1) comprises the following steps:

(la) taking a rectangular metal foil, after folding it, sealing the three sides of the opening to form a pouch-like metal foil;

(lb) Clean the residual contaminants after the pressure welding with an organic solvent.

Step (lb) The selection of the organic solvent for cleaning residual contaminants after pressure welding is a technique well known to those skilled in the art, and typical, but non-limiting examples of the organic solvent are ethanol, acetone or n-hexane.

Preferably, the removing the oxygen in the vacuum chamber according to the step (3) comprises the following steps:

(3a) evacuating the vacuum chamber;

(3b) injecting an inert gas into the vacuum chamber;

(3c) vacuuming the vacuum chamber again;

(3d) ho repeating step (3b) and the step (3c), the vacuum chamber until the oxygen partial pressure lxl0_ ⁶ torr. Preferably, ho step (3a) is evacuated to a vacuum state 2-15xl0- ² torr, e.g. ^{2><10_ 2 torr, 2.3} l0 "2 torr. 2.7 l0" 2 torr, 4.2 l0 "2 torr, 4.9 l0" ² torr, 6.1 l0" ² torr, 6.7 l0" ² torr, 7.5xl (T ² torr, 8.7 l0" ² torr, 9 l0" ² torr, 11.4xl0 ^-2 torr, 12.9 l0" ² torr, 13.9 l0" ² Torr, 14.4xl0" ² torr, 14.7xl0" ² torr 15xl() - ² torr, etc., preferably 3-10xl (r ² torr, most preferably 4-8x1 (r ² torr; preferably, step (3b) inert gas The injection amount is such that the pressure in the vacuum chamber is 10 torr, for example, 10 torr, 15 torr, 24 torr, 30 torr, 48 torr, 62.1 torr, 70 torr, 90 torr, lOOtorr, 101 torr, 103.1 torr, 163 torr, 203 torr, 255 torr 708 tor, 1020 torr, etc., preferably 100 torr .

Preferably, the inert gas of the step (3b) is selected from the group consisting of nitrogen, helium, neon, argon, helium, Any one or a combination of at least two of helium, such as nitrogen/helium, helium/helium, argon/helium, helium/helium/helium, helium/helium/argon Gas and so on. The present invention is the purity of the inert gas is not particularly limited, and only need to remove oxygen in the vacuum chamber to achieve a partial pressure of oxygen as the standard lxl0- ⁶ torr, and preferably, the purity of the inert gas according to the present invention 99.99%.

Preferably, step (3c) is evacuated to a vacuum state 2-15xl0- ² torr, e.g. ^{2><10_ 2 toiT, 2.1x10-} 2 torr, 3.7x10- 2 torr, 4.9x10- 2 torr, 5.9x10- 2 Torr, 6.2x10— ² torr, 7.1x10— ² torr, 8.6xl0” ² torr.10.8xl0" ² torr, llxl0" ² torr, 11.8xl0" ² torr.12.7 l0" ² torr, 13.5xl0" ² torr, 14.9 X10 - ² torr, 14.3xl0 - ² torr, 15 l0" ² torr, preferably 3-10xl0 - ² torr, most preferably 4-8x10 - ² torr.

Preferably, the number of repetitions of the step (3b) and the step (3c) described in the step (3d) is 2-8 times, for example, 2 times, 4 times, 5 times, 7 times, 8 times, preferably 2-5 times, Most preferably 2-3 times.

Step (3) The purpose of removing oxygen in the vacuum chamber is to prevent the graphene obtained by high temperature atomic dialysis from reacting with the gas in the vacuum chamber, especially with oxygen therein. Thus, step (3) requires repeated "evacuation - filled with an inert gas - vacuuming - filled with an inert gas" step, the vacuum chamber until the oxygen partial pressure lxl (T ⁶ torr, should be apparent to those skilled in the art The lower the oxygen partial pressure described here, the better the quality of the finally obtained graphene. For example, the partial pressure of oxygen is l l0" ⁶ torr, 0.98 l0" ⁶ torr, 0.92 l0" ⁶ torr, 0.82 l0 " ⁶ torr, 0.88xl (T ⁶ torr, etc.).

In the present invention, the gas injection flow rate is independently selected from 1-100 sccm, such as l.lsccm, 1.9 sccm, 3.5 sccm, 9.7 sccm, 15 sccm, 29 sccm, 44 sccm, 69 sccm, 87 sccm, 98 sccm, 99.5 sccm, etc., preferably 4- 96 sccm, further preferably 20-80 sccm. The injection flow rate of the gas includes the inert gas described in the step (3), the reducing gas (hydrogen gas) described in the step (4), and the carbon source gas and the reducing gas described in the step (6), and the step ( 8) The inert gas or the like.

Preferably, the purity of the reducing gas and the carbon source gas of the present invention is independently defined to be 99.99%. Preferably, the reducing gas (hydrogen) of the present invention has a purity of 99.99%, for example, 99.991%, 99.999% and so on.

Preferably, the inert gas flow rate of the present invention is preferably 4-96 sccm, further preferably 20-80 sccm; preferably, the injection flow rates of the reducing gas and the carbon source gas described in the steps (4) and (6) are independently Limited to l-100sccm.

Preferably, the reducing gas flow rate according to the present invention is preferably 4-60 sccm, further preferably 10-30 sccm;

Preferably, the carbon source gas flow rate according to the present invention is preferably from 1 to 40 sccm, further preferably from 1 to 10 sccm. Preferably, the carbon source gas of the present invention has a purity of 99.99%, for example, 99.991%, 99.999%, and the like. Step (5) The temperature of the temperature rise is a dialysis temperature of the carbon atoms obtained by decomposition of the carbon source and a growth temperature of the graphene, depending on factors such as the kind of the substrate, the kind of the carbon source, and the like. Preferably, the temperature of the temperature rising in the step (5) is 800-1150 ° C, for example, 800 ° C, 801 ° C, 817 ° C, 832 ° C, 897 ° C, 922 ° C, 989 ° C, 1020 °C, 1090 ° C, 1106 ° C, 1130 ° C, 1170 ° C, 1200 ° C, etc., preferably 800-1100 ° C, further preferably 880-1080 ° C, particularly preferably 950-1050 ° C;

Step (7) The rate of cooling determines the speed of graphene deposition and the appearance of graphene deposited. Preferably, step (7) is to reduce the temperature to room temperature, and the temperature drop rate is 2-18 ° C. /s, for example 2.1 °C / s, 2.7 ° C / s, 5.8 ° C / s, 6.9 ° C / s, 7.6 ° C / s, ll ° C / s, 13.5 ° C / s, 16 ° C / s, 17.8. Preferably, C/s or the like is 3-9 ° C / s, and further preferably 8 ° C / s.

The present invention has obtained graphene deposited on a substrate through steps (1) - (7), but if a momentary release of pressure, a large amount of air is poured into the vacuum chamber, it will definitely cause oxidation of graphene, how to make it. The graphene is taken out and ensured that it is not oxidized by oxygen in the air, and step (8) is required. The step (8) includes the following steps:

( 8a) closing the reducing gas intake valve, the carbon source gas intake valve and the vacuum pump;

(8b) Open the inert gas inlet valve and fill with inert gas until the pressure in the vacuum chamber is 1 atmosphere; ( 8c) Remove the substrate.

The invention is based on a chemical vapor deposition method for pyrolyzing formazan or other hydrocarbon gas on the outer surface of a closed charge-like metal substrate (for example, copper foil, nickel foil, nickel-copper alloy, etc.), and the deposited carbon atoms are at a high temperature. The inner surface of the metal substrate is dialyzed to form a graphene film on the inner surface. In this method, graphene is formed at a slower rate, and the formed graphene grains are larger, thereby providing a method for preparing an ultra-large grain graphene film.

The present invention can be realized by an experimental apparatus capable of achieving the above object, and a person skilled in the art can realize a process of preparing a single layer and a plurality of layers of graphene by chemical vapor deposition according to his own expertise. A preferred embodiment of the invention is accomplished in a vacuum reactor. The vacuum reactor of the present invention is well known to those skilled in the art, and typically, but not exclusively, a tube furnace or an atmosphere furnace.

As a preferred technical solution, the method for preparing graphene by high-temperature atomic dialysis based on chemical vapor deposition according to the present invention is carried out in a chemical vapor deposition system, which comprises an inert gas flow meter, a hydrogen flow meter 2, and carbon. The source gas flow meter 3, the quartz tube 4, the tube furnace 5, the vacuum gauge 6, and the substrate 7 are composed; wherein, the quartz tube 4 is placed in the tube furnace 5, and one side of the quartz tube 4 passes through the inert gas flow meter 1. The hydrogen flow meter 2 and the carbon source gas flow meter 3 are respectively connected to an inert gas, a hydrogen gas, and a carbon source gas cylinder, and the other side of the quartz tube 4 is sequentially connected to the vacuum gauge 6 and the vacuum pump.

As an alternative technical solution, the quartz tube and the tube furnace can be replaced with an atmosphere furnace having a larger space, and the operation steps are the same as those of the above tube furnace.

As an alternative technical solution, the method for preparing the graphene by high temperature atomic dialysis based on chemical vapor deposition of the present invention comprises the following steps:

( la ) taking a rectangular metal foil of a certain size, after folding it, sealing the three sides of the opening to form a pouch-like metal foil;

( lb ) cleaning the residual contaminants after pressure welding with an organic solvent; (2) placing a charge-like metal substrate in a vacuum reactor;

(3a) evacuating the vacuum chamber;

(3b) injecting an inert gas into the vacuum chamber;

(3c) vacuuming the vacuum chamber again;

(3d) repeating step (3b) and step (3c) until the oxygen in the vacuum chamber is divided by lxl0_ ⁶ torr;

(4) injecting hydrogen into the vacuum chamber;

(5) Warming up to 800-1100 °C;

(6) injecting a carbon source gas into the vacuum chamber while maintaining the hydrogen flow rate;

(7) After Ι-lOOmin, a metal substrate on which graphene is deposited;

(8a) closing the reducing gas intake valve, the carbon source gas intake valve, and the vacuum pump;

(8b) Open the inert gas inlet valve and fill with inert gas until the pressure in the vacuum chamber is 1 atmosphere;

(8c) Remove the substrate.

Alternatively, the method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition comprises the following steps:

(la) taking a rectangular metal foil of a certain size, after folding it, sealing the three sides of the opening to form a pouch-like metal foil;

(lb) cleaning the residual contaminants after the pressure welding with an organic solvent;

(2) placing a charge-like metal substrate in a vacuum reactor;

(3a) evacuating the air pressure of the tube furnace or the atmosphere furnace to 4-8X 10- ² torr _;

(3b) injecting 99.99% pure inert gas into the vacuum chamber at a gas flow rate of 1-100 sccm;

(3c) Close the inert gas inlet valve and draw the air pressure of the tube furnace or the atmosphere furnace to the limit 4-8 l0" ² torr;

(3d) repeating step (3b) and step (3c) until the oxygen in the vacuum chamber is divided by lxl0_ ⁶ torr; (4) injecting hydrogen into the vacuum chamber;

(5) Warm up to 800-1100 ° C, and keep at the highest temperature l-100min while maintaining the protective airflow

(7) After 1 to 100 minutes, a metal substrate on which graphene is deposited;

(8b) Open the inert gas inlet valve and fill with inert gas until the pressure in the vacuum chamber is 1 atm; (8c) Remove the substrate.

Optionally, the present invention is implemented by the following technical solutions:

A method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition, and the steps are as follows:

(1) Take a rectangular copper foil of a certain size, after folding it, seal the three sides of the opening to form a purple-like copper foil; then use organic solvent to clean the residual contaminants after the welding;

(2) The pouch-like copper foil is placed in a vacuum reactor, and in the case of removing oxygen in the vacuum chamber, hydrogen gas is injected into the vacuum chamber, and the temperature is raised to 800-1100 ° C, and the carbon source gas is injected into the vacuum chamber. At the same time, the hydrogen flow rate is maintained, and the encapsulated copper foil of graphene is deposited after l-100 min.

Preferably, the method for removing oxygen in the vacuum chamber is:

(1) pumping the air pressure of the tube furnace or the atmosphere furnace to the ultimate vacuum state 4-8X10_ ² torr _;

(2) injecting an inert gas having a purity higher than 99.99% into the vacuum chamber at a gas flow rate of 1-100 sccm;

(3) Close the inert gas inlet valve and pump the air pressure of the tube furnace or the atmosphere furnace to the limit of 4-8X 10" ² torr _;

(4) Repeat steps (2) and (3) 2-3 times, until the atmosphere in the furnace or tube furnace residual oxygen in addition to the oxygen partial pressure is less than lX10- ⁶ torr.

Preferably, the method for taking out the graphitic copper foil depositing graphene is: turning off the hydrogen gas and the carbon source gas The body valve, the vacuum pump, and the atmospheric pressure of the tube furnace or the atmosphere furnace are filled with an inert gas to an atmospheric pressure state, and then the pouch-shaped copper foil is taken out.

Preferably, the hydrogen and carbon source gases have a flow rate of from 1 to 100 sccm and a purity of more than 99.99%. Preferably, the carbon source gas is an organic gas containing only hydrocarbon atoms.

Preferably, the carbon source gas is formazan.

A second object of the present invention is to provide a graphene prepared by the above-mentioned high-temperature atomic dialysis method based on chemical vapor deposition, wherein the thickness of the graphene is controllable; the thickness of the graphene is a single atomic layer graphene or a polyatomic layer Graphene.

The present invention obtains a monoatomic layer graphene or a polyatomic layer of graphene by selecting the kind and thickness of the metal substrate, controlling the operating conditions of the carbon source gas and the reducing gas, the temperature of the heating, and the rate of temperature drop.

Preferably, the graphene is a polyatomic layer graphene;

Preferably, the graphene is a monoatomic layer graphene.

A third object of the present invention is to provide a use of graphene prepared by a method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition, which is used for energy storage active materials, microprocessors, batteries, displays, and Flexible electronics, preferably for hydrogen storage, lithium-ion batteries, supercapacitors or fuel cells, as well as nanoelectronics, high frequency circuits, photon sensors, gene electronics sequencing, noise reduction, high frequency / RF transistors, flat panel displays and flexible displays .

Compared with the prior art, the present invention has the following beneficial effects:

(1) The graphene provided by the present invention has an extremely high crystal quality, and the crystal size (crystal domain) can reach 500 μm;

(2) The graphene product provided by the invention has excellent light transmittance (transmittance is better than 97%);

(3) The thickness of the graphene provided by the present invention is controllable from a single layer to a multilayer, and a monoatomic layered stone is easily obtained. Motenol.

DRAWINGS

1 is a schematic view showing the fabrication of the metal substrate according to the step (1) of the present invention;

2 is a schematic structural view of a chemical vapor deposition system according to Embodiments 1 to 4 of the present invention;

Fig. 3 is a scanning electron microscope image of graphene prepared in Example 3 of the present invention.

Reference numeral

1-inert gas flow meter; 2-hydrogen flow meter; 3-carbon source gas flow meter; 4-quartz tube; 5-tube furnace; 6-vacuum gauge;

detailed description

In order to facilitate the understanding of the present invention, the present invention is exemplified by the following. It should be understood by those skilled in the art that the present invention is not to be construed as limited.

In the embodiment of the present invention, high-temperature atomic dialysis is performed by using a metal copper foil of 100 mm ² as a substrate, but those skilled in the art should understand that the metal substrate of the present invention can be replaced, for example, a copper foil of 100 mm ² can be replaced with Other metal substrates, for example, may be replaced by 80 mm ² copper foil, 120 mm ² copper foil, 50 mm ² copper-nickel alloy metal foil, 150 mm ² nickel foil, 200 mm ² copper-palladium-nickel metal foil, 40 mm ² The copper-ruthenium metal foil or the like, the specific preparation conditions thereof can be inferred by the prior art or new technology grasped by those skilled in the art according to the preparation process of the present invention.

Figure 1 is a schematic view showing a metal substrate made of a metal copper foil of 100 mm ² . The preparation process of the metal substrate is specifically as follows:

(1) After folding the metal copper foil of 100 mm ² in half, the three sides are sealed by a pressure welding machine to form a bag-shaped metal copper foil;

( lb) Wash the residual contaminants after pressing with an organic solvent.

Example 1 A graphene film is prepared on the inner surface of the encapsulated copper foil by chemical vapor deposition, and the method is carried out in a chemical vapor deposition system, including the following preparation steps:

(1) preparing a charge-like metal substrate;

(2) taking the pouch-like copper foil substrate 7 prepared above into the quartz tube 4;

(3a) Open the vacuum pump to pump the air pressure of the quartz tube 4 to the ultimate vacuum state 4 X l (T ² torr _;

(3b) The inert gas flow meter 1 is set to 5 _SCC m, and argon gas is injected into the vacuum chamber;

(3c) After 4.5 min, close the inert gas flow meter 1 wide door and draw the air pressure of the tube furnace 5 to the limit of 8 X 10 — ² torr:

(3d) repeating steps (3b) and the step (3c) procedure three times; until the residual oxygen and clean the quartz tube 4 is driven to the oxygen partial pressure is less than l X 10- ⁶ _torr;

(4) The hydrogen flow meter 2 is set to 5 _SCC m to inject hydrogen into the vacuum chamber;

(5) Raise the temperature of the tube furnace 5 to 1000 ° C _;

(6) The carbon source gas flow meter 3 sets 5 _SCC m to inject the nail into the vacuum chamber;

(7) The temperature of the tube furnace 5 is lowered to room temperature, and the temperature drop rate is 2 ° C / s.

(8a) Close the hydrogen flow meter 2. Carbon source gas flow meter 3 valve and vacuum pump;

(8b) Inert gas flow meter 1 is set to 50sccm, and the quartz tube 4 air pressure is filled with argon gas to an atmospheric pressure state;

( 8c) Open the quartz tube 4 vacuum port, take it out, and cut the seal to obtain a copper foil substrate 7 on which graphite is deposited on the inner surface.

Figure 2 is a schematic view showing the structure of a chemical vapor deposition system according to Examples 1-4 of the present invention.

Example 2

A graphene film is prepared on the inner surface of the encapsulated copper foil by chemical vapor deposition, and the method is carried out in a chemical vapor deposition system, including the following preparation steps: (1) preparing a charge-like metal substrate;

(2) taking the pouch-like copper foil substrate prepared above, placed in the quartz tube 4;

(3a) the vacuum pump 4 to the pressure of the quartz tube evacuated to ultimate vacuum of 8X10- ² _torr;

(3b) is set to an inert gas flow meter 50 sccm, helium gas injected into the vacuum chamber; after (3c) 4.5min, an inert gas flow to close the valve 1, the pressure tube furnace evacuated to the limit of 5 4X10- ² Torr;

(3d) repeating steps (3b) and the step (3c) procedure twice; until residual oxygen in a clean quartz tube 4 is driven to the oxygen partial pressure is less than lX10- ⁶ _torr;

(4) The hydrogen flow meter 2 is set to 50 _SCC m to inject hydrogen into the vacuum chamber;

(5) Raise the temperature of the tube furnace 5 to 900 ° C _;

(6) Carbon source gas flow meter 3 Set lOsccm to inject ethane into the vacuum chamber;

(7) The temperature of the tube furnace 5 is lowered to room temperature, and the cooling rate is 15 ° C / s;

(8a) Close the hydrogen flow meter 2. Carbon source gas flow meter 3 door and vacuum pump;

(8b) Inert gas flow meter 1 is set to lOOsccm, and the gas pressure of the quartz tube 4 is filled with helium gas to an atmospheric pressure state;

(8c) Open the quartz tube 4 vacuum port, take it out, and cut the seal to obtain a copper foil substrate 7 on which graphite is deposited on the inner surface.

Example 3

A graphene film is prepared on the inner surface of the encapsulated copper foil by chemical vapor deposition, and the method is carried out in a chemical vapor deposition system, and includes the following preparation steps:

(1) preparing a charge-like metal substrate;

(3a) Open the vacuum pump to pump the air pressure of the quartz tube 4 to the ultimate vacuum state 6X10_ ² torr; (3b) The inert gas flow meter 1 is set to 1000sccm, and nitrogen gas is injected into the vacuum chamber; (3c) After 4.5 minutes, the inert gas flow meter 1 valve is closed, and the gas pressure of the tube furnace 5 is drawn to the limit 6 X 10- ² torr;

(3d) repeat the steps of step (3b) and step (3c) twice; until the residual oxygen of the quartz tube 4 is driven clean until the oxygen partial pressure is less than ix io_ ⁶ t _orr;

(4) The hydrogen flow meter 2 is set to lOOsccm, and hydrogen is injected into the vacuum chamber;

(5) Raise the temperature of the tube furnace 5 to 800 ° C;

(6) The carbon source gas flow meter 3 sets 20 _SCC m to inject ethylene into the vacuum chamber;

(7) The temperature of the tube furnace 5 is lowered to room temperature, and the cooling rate is 10 ° C / s;

(8b) The inert gas flow meter 1 is set to 75 _SCC m, and the quartz tube 4 air pressure is filled with nitrogen to an atmospheric pressure state;

Example 4

A graphene film is prepared on the inner surface of the encapsulated copper foil by chemical vapor deposition, and the method is carried out in a chemical vapor deposition system, which comprises the following preparation steps:

(1) preparing a charge-like metal substrate;

(3a) the vacuum pump 4 to the pressure of the quartz tube evacuated to ultimate vacuum of 2xl0- ² _torr;

(3b) Inert gas flow meter 1 is set to 50sccm, and helium and nitrogen are introduced into the vacuum chamber at a volume ratio of 1:4;

(3c) After 7 minutes, close the inert gas flow meter 1 valve and draw the pressure of the tube furnace 5 to the limit. lS lO^torr:

(3d) repeat the steps of step (2b) and step (2c) 8 times; until the residual oxygen of the quartz tube 4 is driven clean until the partial pressure of oxygen is less than 0.89xl0_ ⁶ torr;

(4) The hydrogen flow meter 2 is set to lsccm, and hydrogen gas is injected into the vacuum chamber;

(5) Raise the temperature of the tube furnace 5 to 1150 ° C;

(6) The carbon source gas flow meter 3 is set to 1.5 _SCC m, and cis 1,3-butadiene is injected into the vacuum chamber;

(7) The temperature of the tube furnace 5 is lowered to room temperature, and the cooling rate is 2 ° C / s _;

(8b) Inert gas flow meter 1 is set to SOsccm, and the quartz tube 4 is filled with helium gas to an atmospheric pressure state;

( 8c) Open the quartz tube 4 vacuum port and take out the nickel film substrate 7 on which graphene has been deposited.

Wherein, the purity of hydrogen and 1,3-butadiene gas is independently limited to ^99.99%

The present invention uses a scanning electron microscope SEM image of a single layer of graphene to characterize the crystal size of the prepared graphene. It can be seen that the obtained graphene coverage is <50%. The darker gray areas in Fig. 3 are single-layer graphene surrounded by a metallic copper substrate. It can be seen from the figure that the crystal size (crystal domain) of the prepared graphene is about 0.5 mm.

It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, although the present invention has been described in detail with reference to the foregoing embodiments, The technical solutions described in the foregoing embodiments may be modified, or some of the technical features may be equivalently replaced. Any modifications, equivalent substitutions, improvements, etc., which are within the scope of the invention, are intended to be included within the scope of the invention.

Claims

Claim

A method for preparing graphene by high temperature atomic dialysis based on chemical vapor deposition, characterized in that the method is to deposit a carbon source gas on a charge-bearing metal substrate by gradually decreasing the temperature from a high temperature in a reducing atmosphere. Thereby, a single layer and/or a plurality of layers of graphene deposited on the inner side of the bag-like metal substrate are obtained; the reducing atmosphere is a hydrogen atmosphere.

2. The method according to claim 1, wherein the method for preparing the packet-shaped metal substrate is: taking a rectangular metal substrate, after folding, sealing three sides of the opening to form a pouch-like copper foil;

Preferably, the metal in the metal substrate is selected from any one or a combination of at least two of nickel, copper, ruthenium, cobalt, palladium, platinum, rhodium or ruthenium, preferably copper foil, nickel foil, nickel-copper Any one or a combination of at least two of an alloy foil, a copper-bismuth-nickel alloy foil, and a copper-cobalt alloy foil, and preferably one or at least two of copper foil, nickel foil or nickel-copper alloy foil. Combination of species;

Preferably, the carbon source gas is an organic gas containing only carbon atoms and hydrogen atoms, and preferably any one or at least two of C1-C4 anthracene, C2-C4 olefin, and C2-C3 alkyne. Combination, further preferably, formazan, ethane, ethylene, acetylene, propylene, n-butene, isobutylene, 1,2-butadiene, 1, 3-butadiene, cis-butadiene, anti-dibutene, Any combination of at least one of n-butyl sulfonium, isobutyl hydrazine, propylene, and propylene fluorene is particularly preferably methane.

3. The method of claim 1 or 2, wherein the method comprises the steps of:

(1) preparing a charge-like metal substrate;

(2) placing a charge-like metal substrate in a vacuum reactor;

(3) removing oxygen from the vacuum chamber;

(4) injecting a reducing gas into the vacuum chamber;

(5) heating up;

(6) injecting a carbon source gas into the vacuum chamber while maintaining a reducing gas flow rate; (7) cooling, a metal substrate on which graphene is deposited;

(8) Take out the metal substrate on which graphene is deposited.

4. The method according to claim 3, wherein the step (1) of preparing the charge-packed metal substrate comprises the following steps:

(lb) Washing the residual contaminants after the pressure welding with an organic solvent.

5. The method according to claim 3 or 4, wherein the removing the oxygen in the vacuum chamber by the step (3) comprises the steps of: (3a) evacuating the vacuum chamber; (3b) injecting the inert gas a vacuum chamber; (. 3C) the vacuum chamber was evacuated again; (3D) repeating steps (3b) and ho step (3c), the vacuum chamber until the oxygen partial pressure 1x10- ⁶ torr;

Preferably, step (3a) is evacuated to a vacuum of 2-15 x 10 - ² torr, preferably 3 - 10 x 10 - ² torr, and most preferably 4 - 8 x 10 - ² torr;

Preferably, the inert gas of the step (3b) is injected in such a manner that the pressure in the vacuum chamber is 10 torr, preferably 100 torr; preferably, the inert gas in the step (3b) is selected from the group consisting of nitrogen, helium, neon, argon, Any one or a combination of at least two of helium and neon;

Preferably, step (3c) is evacuated to a vacuum of 2-15 x 1 (T ² torr, preferably 3-10 x 1 (T ² torr, most preferably 4-8 x 1 (T ² torr;

Preferably, the number of repetitions of the step (3b) and the step (3c) described in the step (3d) is 2-8 times, preferably 2-5 times, and most preferably 2-3 times.

6. The method according to claim 3-5, characterized in that the temperature of the temperature rising in the step (5) is 800 to 1150 ° C, preferably 800 to 1100 ° C, further preferably 880 to 1080 ° C, in particular Preferably, 950-1050 ° C; preferably, the injection flow rate of the reducing gas and the carbon source gas described in the step (4) and the step (6) Independently defined as 1-100 sccm; the reducing gas flow rate, further preferably 4-60 sccm, particularly preferably 10-30 sccm; the carbon source gas flow rate, further preferably 1-40 sccm, particularly preferably 1-10 sccm; preferably, The purity of the reducing gas and the carbon source gas is independently defined as 99.99%;

Preferably, the temperature drop is reduced to room temperature, and the temperature drop rate is 2-18 ° C / s, preferably 3-9 ° C / s, further preferably 8 ° C / s.

7. The method according to any one of claims 3-6, wherein the removing the metal substrate on which the graphene is deposited in the step (8) comprises the steps of:

(8b) opening the inert gas intake valve, filling the inert gas into the vacuum chamber at a pressure of 1 atmosphere;

( 8c) Remove the substrate.

8. A method according to any one of claims 3-7, characterized in that the method comprises the steps of: (la) taking a rectangular metal foil of a certain size, after folding it, sealing the three sides of the opening to form a Pruned metal foil;

( lb) cleaning the residual contaminants after the pressure welding with an organic solvent;

(2) placing a charge-like metal substrate in a vacuum reactor;

(3a) vacuuming the vacuum chamber;

(3b) injecting an inert gas into the vacuum chamber;

(3c) vacuuming the vacuum chamber again;

(3d) repeating step (3b) and step (3c) until the oxygen in the vacuum chamber is divided by l xl0_ ⁶ torr;

(4) injecting hydrogen into the vacuum chamber;

(5) Warming up to 800-1100 °C;

(7) After l-100min, a metal substrate of graphene is deposited; ( 8a) closing the reducing gas intake valve, the carbon source gas intake valve and the vacuum pump;

( 8c) Remove the substrate.

A graphene prepared by the method according to any one of claims 1-8, wherein the graphene has a thickness that is controllable;

Preferably, the graphene is a polyatomic layer graphene;

Preferably, the graphene is a monoatomic layer graphene.

10. Use of graphene according to claim 9, characterized in that the graphene is used for energy storage active materials, microprocessors, batteries, displays and flexible electronic devices, preferably for hydrogen storage, lithium Ion batteries, supercapacitors or fuel cells, as well as nanoelectronics, high frequency circuits, photonic sensors, gene electronics sequencing, noise reduction, HF/RF transistors, flat panel displays and flexible displays.