KR20170112026A - Method for preparation of graphene - Google Patents

Abstract

The graphene production method according to the present invention is characterized in that the graphene precursor is treated by an electrochemical method to improve the production efficiency of graphene and the size of the graphene to be produced is uniform compared with the conventional process.

Description

Method for preparation of graphene [0002]

The present invention relates to a method of producing graphene using a method of electrochemically treating a graphene precursor.

Graphene is a semimetallic material with a thickness corresponding to the carbon atomic layer, with the carbon atoms forming a hexagonally connected arrangement in two dimensions on the sp2 bond. Recently, evaluation of the characteristics of a graphene sheet having one carbon atom layer has revealed that the electron mobility is about 50,000 cm ² / Vs or more, which can exhibit a very good electric conductivity.

Graphene also has structural, chemical stability and excellent thermal conductivity characteristics. In addition, it is easy to process one- or two-dimensional nanopatterns composed of carbon, which is a relatively light element. Graphene is expected to replace silicon-based semiconductor technology and transparent electrodes due to its electrical, structural, chemical, and economic properties, and it is expected to be applicable to flexible electronic devices due to its excellent mechanical properties.

Due to the many advantages and excellent properties of such graphenes, various methods have been proposed or studied to more effectively produce graphene from carbon-based materials such as graphite. Particularly, there have been various studies on a method for easily producing a graphene sheet or flake having a thinner thickness and a larger area so that excellent characteristics of graphene can be more dramatically developed. Such conventional methods of producing graphene include the following.

First, a method of peeling a graphene sheet from graphite by a physical method such as using a tape is known. However, this method is not suitable for mass production methods, and the peeling yield is also very low.

There is known a method for obtaining graphene or an oxide thereof which is peeled off from an intercalation compound in which an acid, a base, a metal or the like is interposed between carbon layers of graphite, or by peeling by a chemical method such as oxidizing graphite.

However, in the former method, a large number of defects may be generated on the finally produced graphene in the process of oxidizing the graphite to proceed the exfoliation and reducing the graphene oxide obtained therefrom to obtain graphene again. This may adversely affect the properties of the final produced graphene. In addition, the latter method requires additional processes such as using and treating an intercalation compound, which may complicate the overall process, resulting in a low yield and a low cost. Further, in this method, it is not easy to obtain a large-area graphene sheet or flake.

Recently, a method of producing graphene by separating carbon layers contained in graphite by ultrasonic irradiation or a milling method using a ball mill or the like has been applied most recently in the state where graphite or the like is dispersed in a liquid state. However, these methods have also been problematic in that it is difficult to obtain graphene having a sufficiently thin thickness and a large area, a large number of defects are formed on the graphene in the peeling process, or the yield of peeling is insufficient.

As a result, there is a continuing need for a manufacturing method capable of easily producing a graphene sheet or flake having a thinner thickness and a larger area with higher yield.

The present invention is to provide a method for producing graphene which can produce graphene of uniform size with excellent efficiency.

In order to solve the above problems, the present invention provides a process for producing graphene comprising the steps of:

A first electrode comprising a graphene precursor; A second electrode; And separating the graphene precursor from the first electrode by applying a voltage to the first electrode and the second electrode in an electrolyte contained between the first electrode and the second electrode (step 1);

High-speed homogenization of the dispersion solution containing the exfoliated graphene precursor and dispersant to prepare a feed solution (Step 2); And

Passing the feed solution through an inlet, an outlet, and a high pressure homogenizer including a microfluidic channel having a micrometer scale diameter connecting between the inlet and the outlet (step 3).

The term "graphite" used in the present invention refers to a material which is also called graphite or talc and belongs to a hexagonal system having a crystal structure such as quartz, and is a material having a black color and metallic luster. The graphite has a plate-like structure. A single layer of graphite is called "graphene" to be produced in the present invention, and thus graphite becomes the main raw material for the production of graphene.

In order to peel off graphene from the graphite, energy that can overcome the pi-pi interaction between the stacked graphenes should be applied. In the present invention, the high-pressure homogenization method is used as in step 3 described later. The high-pressure homogenization method can apply a strong shear force to the graphite, so that the graphene peeling efficiency is excellent. However, if the graphite in the feed solution used for high-pressure homogenization is not sufficiently dispersed, the processability and efficiency of the high-pressure homogenization process deteriorate. In order to increase the peeling efficiency of high-pressure homogenization, it is preferable that the interlayer spacing of graphite is wider than that of pure graphite. In this invention, electrochemically expanded graphite is used as step 1 as described above.

Accordingly, when electrochemically expanded graphite is applied to high-pressure homogenization as compared with a method in which pure graphite is directly applied to high-pressure homogenization, not only the peeling efficiency is improved but also the thickness of the produced graphene is thinner, Lt; / RTI >

Hereinafter, the present invention will be described in detail.

Grapina  A first electrode comprising a precursor; A second electrode; And separating the graphene precursor from the first electrode by applying a voltage to the first electrode and the second electrode in the electrolyte contained between the first electrode and the second electrode (step 1)

The step 1 is a step of peeling the graphene precursor from the first electrode including the graphene precursor, and is also referred to as electrochemical exfoliation (ECE) because of using a voltage or the like.

The peeling process of the graphene precursor according to the step 1 is schematically shown in FIG.

As shown in FIG. 1, in an apparatus including a first electrode, a second electrode, and an electrolyte, the first electrode includes a graphene precursor and serves as a cathode, and the second electrode serves as an anode. When a voltage is applied to it, water is reduced in the cathode, which causes a nucleophilic attack by hydroxyl (HO ^- ) on the edge of the graphene precursor or part of the graphene layer. Here oxidation progresses and the space between the graphene layers expands, and ions contained in the electrolyte permeate between the graphene layers. The infiltrated ions are reduced and the water is self-oxidized, so that various gaseous substances (for example, SO ₂ , O _2, etc.) are generated between the graphene layers, The separation of the graphene precursor proceeds.

In the first electrode comprising the graphene precursor, the graphene precursor is preferably graphite. More preferably, the first electrode is made of graphite, and for example, a graphite foil can be used. In addition, the graphene precursor peeled off in the step 1 should be understood as a material in which the distance between the graphene layers in the graphene precursor used for the first electrode is widened or the graphene layers are separated from each other.

The second electrode is not particularly limited as long as it is a conductive material and preferably a Pt electrode, an Au electrode, a carbon rod, a graphite electrode, a steel electrode, an Hg electrode, an Ag electrode, a Cu electrode, W electrodes can be used.

The electrolyte may contain sulfate ions. The concentration of the sulfate ion contained in the electrolyte is preferably 0.01 M to 10 M, more preferably 0.1 M to 1 M. The sulphate ions can be from a variety of compounds, for example as _{(NH 4) 2 SO 4,} Na 2 SO 4, (NH 4) 2 S 2 O 8, K 2 SO 4, H 2 S0 4, ammonium lauryl Sodium lauryl sulfate, potassium lauryl sulfate, sodium myreth sulfate, sodium dodecyl sulfate, sodium laureth sulfate, or sodium lauryl sulfate, sodium lauryl sulfate, sodium lauryl sulfate, It can be derived from sodium pareth sulfate. For example, the above materials may be dissolved in water and used as an electrolyte.

Also, the electrolyte may be at least one selected from the group consisting of H ₂ Cr ₂ O ₇ , HMnO ₄ , HBr, HNO ₃ , HCl, HI, HClO ₃ , HClO ₄ , H ₃ PO ₄ , p-toluenesulfonic acid, triflic acid, The compounds of the present invention can be used in the form of salts such as carborane superacid, fluoroantimonic acid, acetic acid, citric acid, borane acid, diethylbarbituric acid, sodium benzenesulfonate, sodium dodecylbenzenesulfonate ), Dioctyl sodium sulfosuccinate, perfluorobutanesulfonic acid, perfluorooctanesulfonic acid, perfluorononanoic acid, perfluorooctanoic acid, perfluorooctanoic acid, perfluorooctanoic acid, sodium peroxide, perfluorooctanoic acid, sodium palmate, sodium stearate, sodium tallowate, Na ₂ HPO ₄ , KH ₂ PO ₄ , sodium acetate, sodium citrate (sodium ci trate, borax, KMnO ₄ , or K ₂ Cr ₂ O ₇ . For example, the above materials may be dissolved in water and used as an electrolyte. The concentration of the substance contained in the electrolyte is preferably 0.01 M to 10 M, more preferably 0.1 M to 1 M.

The voltage applied to the first electrode and the second electrode is preferably 0.01 to 200 V. In addition, the step 1 is preferably carried out for 1 minute to 3 hours, more preferably 10 minutes to 1 hour.

On the other hand, as the graphene precursor is peeled off from the first electrode in the step 1, precipitation occurs in the electrolyte solution. Therefore, the precipitate can be recovered and used in Step 2 to be described later. The recovery method is not particularly limited, and for example, filtration or the like can be used. Further, after the recovery, washing with water may be further included.

remind Peeled Grapina  The dispersion solution containing the precursor and the dispersing agent is subjected to high- Homogenized Feed  The step of preparing the solution (step 2)

The step 2 is a step of preparing a feed solution to be applied to the high-pressure homogenization of step 3, which will be described later, and the dispersion solution containing the graphene precursor prepared in the step 1 is dispersed in the dispersion solution of the graphene precursor This is to increase the degree.

A dispersant is used to increase the degree of dispersion of the expanded graphite. The dispersants act to maintain their dispersed state mediated by hydrophobic expanding graphites, delaminated expanded graphite or graphene due to their amphiphilic nature, and are also referred to as surfactants in other terms. As the dispersing agent, any dispersant may be used as long as it is used for graphene peeling, and an anionic surfactant, a nonionic surfactant, and a cationic surfactant can be used. Specific examples thereof include pyrene-based low molecular weight derivatives; Cellulosic polymers; Cationic surfactants; Anionic surfactants; Gum arabic; n-Dodecyl b-D-maltoside; Amphoteric surfactants; Polyvinylpyrrolidone type polymers; Polyethylene oxide type polymers; Ethylene oxide-propylene oxide copolymer; Tannic acid; Or a mixture of plural kinds of polyaromatic hydrocarbon oxides, which contains a polyaromatic hydrocarbon oxide having a molecular weight of 300 to 1000 in an amount of 60 wt% or more. Preferably, polyvinyl pyrrolidone can be used.

The weight ratio of the graphene precursor and the dispersant is preferably 2.5 to 20. If it is less than 2.5, the content of the graphene precursor is too low to cause the peeling efficiency in step 3 to be lowered. If the content exceeds 20, the content of the dispersant is too low, thereby deteriorating the dispersing effect of the graphene precursor. More preferably, the weight ratio of the graphene precursor and the dispersant is 2.5 to 5.

The concentration of the graphene precursor in the dispersion solution is preferably 0.5 to 5% by weight. When the amount of the graphene precursor is less than 0.5% by weight, the amount of the graphene precursor is too low and the yield of the step 3 is lowered. When the amount of the graphene precursor is more than 5% by weight, The effect is poor.

The solvent of the dispersion solution may be selected from the group consisting of water, N-methyl-2-pyrrolidone, acetone, N, N-dimethylformamide, DMSO, CHP, N-dodecyl-pyrrolidone ), Benzyl benzoate, N-octyl-pyrrolidone, dimethyl-imidazolidinone, cyclohexanone, dimethylacetamide, NMF (N-Methyl Formamide), bromobenzene, chloroform, chlorobenzene, benzonitrile , Quinoline, benzyl ether, ethanol, isopropyl alcohol, methanol, butanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxypropanol, tetrahydrofuran (THF), ethylene glycol, , Methyl ethyl ketone (butanone), alpha-terpineol, formic acid, ethyl acetate and acrylonitrile may be used.

The high-speed homogenization means stirring the dispersion solution, preferably the dispersion solution is stirred at 3000 to 8000 rpm. The high-speed homogenization is preferably performed for 0.5 to 3 hours. When the time is less than 0.5 hour, there is a limit that the dispersion degree is lowered, and when the time exceeds 3 hours, the dispersion degree does not become substantially higher.

By blending, based on ^{- (1 high shear rate,>} 10 4 sec) the stirring is high-speed homogenizer (high speed homogenizer) water, wherein the high-speed homogenizer rotor and high applied between stator shear rate can be performed using the , And some interstices in the graphene precursor having a wide interlayer spacing are separated. As a result, the size of the graphene precursor becomes small to increase the degree of dispersion in the dispersion solution, and as a feed solution of the high pressure homogenization of step 3 to be described later, the graphene peeling processability improves and the peeling efficiency becomes remarkably high when used.

remind Feed  The solution The inlet , The outlet , The inlet Outlet  And a micrometer-scale Diameter  And a high-pressure In the homogenizer  (Step 3)

This step is a step of homogenizing the feed solution prepared in 2 above under high pressure to peel the graphene from the expanded graphite in the feed solution.

The term 'high pressure homogenization' means applying a high pressure to a micro-channel having a micrometer scale diameter to apply a strong shear force to the material passing through it. Typically, high pressure homogenization is performed using a high pressure homogenizer including an inlet, an outlet, and a microchannel connecting between the inlet and outlet and having a micrometer scale diameter.

The fine flow path preferably has a diameter of 50 to 300 mu m. In addition, it is preferable that the feed solution flows into the inflow portion of the high pressure homogenizer through the micro flow path under a pressure of 500 to 3000 bar.

In addition, according to step 3, the feed solution that has passed through the microfluidic channel can be reintroduced into the inlet of the high-pressure homogenizer, whereby the graphene can be further peeled off from the ungrained graphene precursor.

The reintroduction process may be repeated 2 to 20 times, more preferably 2 to 10 times. The reintroduction process can be carried out repeatedly using the high-pressure homogenizer used or using a plurality of high-pressure homogenizers. In addition, the re-inputting process may be performed separately or sequentially.

On the other hand, it may further include a step of recovering and drying graphene from the graphene dispersion recovered in the outlet according to step 3 above. The recovering step may be carried out by centrifugation, vacuum filtration or pressure filtration. The drying step may be performed by vacuum drying at a temperature of about 30 to 200 ° C.

In addition, the size of the graphene produced according to the present invention is uniform, which is advantageous in expressing characteristics inherent to graphene. The graphene thus prepared may be re-dispersed in various solvents and used for various applications such as a composition for forming a heat dissipation substrate, a conductive paste composition, a conductive ink composition, an electrically conductive composite, an EMI tea composite or a conductive material for a battery or a slurry.

The solvent used in the graphene dispersion may be any of the solvents used in the art. For example, the solvent of the expanded graphite dispersion solution described above may be used.

The graphene production method according to the present invention is characterized in that the graphene precursor is treated by an electrochemical method to improve the production efficiency of graphene and the size of the graphene to be produced is uniform compared with the conventional process.

Fig. 1 schematically shows a manufacturing method of the present invention.
Fig. 2 shows SEM images of graphene prepared in Examples and Comparative Examples of the present invention.
Fig. 3 shows TEM images of graphene prepared in Examples and Comparative Examples of the present invention.
Fig. 4 shows the size distribution of graphene produced in Examples and Comparative Examples of the present invention.
Fig. 5 shows the thermal diffusivity of GF-PMMA prepared using graphene prepared in Examples and Comparative Examples of the present invention.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are shown to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

Example  One

(Step 1)

As shown in Fig. 1, a graphite foil (2.5 cm x 2.5 cm) having a thickness of 0.1 mm to 1 mm is used as a cathode, a Pt mesh electrode having the same area is used as an anode, and an aqueous solution of ammonium sulfate as a 0.1 M is used as an electrolyte Respectively. A direct current of 10 V was applied for 10 minutes. The electrolyte was then vacuum filtered to recover the precipitated graphene precursor, washed with water and dried.

(Step 2)

The graphene precursor and PVP (polyvinylpyrrolidone, molecular weight: 58,000) obtained in step 1 above were dissolved in DMF (graphene precursor 0.5 wt%, PVP 0.1 wt%). This was stirred with a high speed homogenizer (Silverson model L5M mixer) at 5,000 rpm for 30 minutes to prepare a feed solution.

(Step 3)

The feed solution prepared in step 2 was supplied to the inlet of the high pressure homogenizer. The high pressure homogenizer has a structure including an inlet portion of the raw material, an outlet portion of the peeled product, and a microchannel connecting the inlet portion and the outlet portion and having a micrometer scale diameter. A high pressure of 500 bar was applied through the inlet to feed the feed solution so that a high shear force was applied while passing a fine flow path having a diameter of 75 탆. The product recovered from the outlet was reintroduced into the inlet of the high pressure homogenizer and the process was repeated twice, resulting in a product which was passed through the microchannel three times in total.

Example  2

The product was obtained in the same manner as in Example 1, except that 800 bar was used instead of 500 bar in the step 3 of Example 1 above.

Example  3

The product was obtained in the same manner as in Example 1, except that 1100 bar was used instead of 500 bar in the step 3 of Example 1.

Comparative Example  One

Graphite (BNB90) and PVP (polyvinylpyrrolidone, molecular weight 58,000) were dissolved in DMF (graphite 0.5 wt%, PVP 0.1 wt%). This was stirred with a high speed homogenizer (Silverson model L5M mixer) at 5,000 rpm for 30 minutes to prepare a feed solution.

The prepared feed solution was supplied to the inlet of the high pressure homogenizer. The high pressure homogenizer has a structure including an inlet portion of the raw material, an outlet portion of the peeled product, and a microchannel connecting the inlet portion and the outlet portion and having a micrometer scale diameter. A high pressure of 500 bar was applied through the inlet to feed the feed solution so that a high shear force was applied while passing a fine flow path having a diameter of 75 탆. The product recovered from the outlet was reintroduced into the inlet of the high pressure homogenizer and the process was repeated twice, resulting in a product which was passed through the microchannel three times in total.

Comparative Example  2

A product was obtained in the same manner as in Example 1, except that 800 bar was used instead of 500 bar in the microchannel in Comparative Example 1.

Comparative Example  3

A product was obtained in the same manner as in Example 1, except that in Comparative Example 1, 1100 bar was used instead of 500 bar in the microchannel.

Experimental Example  One

The products obtained in the above Examples and Comparative Examples were observed with an SEM image, and the results are shown in Fig.

2 (d) to 2 (e)) according to the present invention, which has been electrochemically treated as shown in Fig. 2, shows a comparative example (Fig. 2 c)). As a result, it was confirmed that a thinner graphene was produced.

In particular, it has been confirmed that the embodiment according to the present invention remarkably improves the degree of peeling in the embodiment according to the present invention as the inter-layer attraction of the graphite decreases due to the electrochemical treatment and the interlayer spacing expands and the pressure of the microchannel increases . On the other hand, in the case of the comparative example, even when the pressure of the microfluidic channel was increased, the degree of improvement as in the example was not shown.

Experimental Example  2

The products obtained in Example 2 and Comparative Example 2 were observed with a TEM image, and the results are shown in Fig.

As shown in Fig. 3, unlike the comparative example (Fig. 3 (a)), the embodiment according to the present invention (Fig. 3 (b)) showed no wrinkled structure in graphene and no chunk. This effect is due to the reduction of the interlayer attraction of the graphite and the expansion of the interlayer spacing according to the electrochemical treatment.

Experimental Example  3

The graphene particle size in the product obtained in Example 2 and Comparative Examples 1 to 3 was analyzed. Specifically, each product was measured for the distribution of laplace size dispersed in a particle size analyzer (LA-960 Laser Particle Size Analyzer). The results are shown in FIG.

As shown in FIG. 4, when the pressure applied to the microchannel was the same as that of Example 2 and Comparative Example 2, the size of the graphene was smaller and the chunk was significantly reduced. In addition, the standard variation was reduced by about 3 times, confirming that more uniform graphene was produced.

Experimental Example  4

In order to confirm the characteristics of the graphene prepared in Examples and Comparative Examples, the thermal diffusivity of GF-PMMA was measured. Specifically, the composite obtained by mixing the graphene and the PMMA prepared in the above Examples and Comparative Examples at a weight ratio of 15:85 was hot-pressed to prepare a 0.5 mm thick film. The prepared film was perforated with a 1 inch ellipse, and both sides were coated with a graphite spray as a whole. The graphite-coated sample was placed in a jig and loaded on a machine (Netzsch, LFA-447), and the thermal diffusivity was measured at three points per sample to calculate the average value (thermal conductivity = thermal diffusivity × specific heat × specific gravity). The results are shown in Fig.

As shown in FIG. 5, the examples showed excellent thermal diffusivity compared to the comparative example regardless of the pressure applied to the micro flow path.

Claims (14)

A first electrode comprising a graphene precursor; A second electrode; And applying a voltage to the first electrode and the second electrode in an electrolyte contained between the first electrode and the second electrode to peel off the graphene precursor from the first electrode;
Rapidly homogenizing the dispersion solution containing the exfoliated graphene precursor and the dispersing agent to prepare a feed solution; And
Passing said feed solution through an inlet, an outlet, and a high pressure homogenizer comprising a microchannel having a micrometer scale diameter connecting between the inlet and outlet,
Graphene.
The method according to claim 1,
Wherein the first electrode comprising the graphene precursor is graphite.
Gt;
The method according to claim 1,
Wherein the second electrode is a Pt electrode, an Au electrode, a carbon rod, a graphite electrode, a steel electrode, an Hg electrode, an Ag electrode, a Cu electrode, a Ti electrode,
Gt;
The method according to claim 1,
Characterized in that the electrolyte comprises sulfate ions.
Gt;
5. The method of claim 4,
The sulfate ion may be selected from the group consisting of (NH ₄ ) ₂ SO ₄ , Na ₂ SO ₄ , (NH ₄ ) ₂ S ₂ O ₈ , K ₂ SO ₄ , H ₂ SO ₄ , ammonium lauryl sulfate, Sodium lauryl sulfate, sodium lauryl sulfate, sodium myreth sulfate, sodium dodecyl sulfate, sodium laureth sulfate, or sodium pareth sulfate. Features,
Gt;
The method according to claim 1,
Wherein the electrolyte is selected from the group consisting of H ₂ Cr ₂ O ₇ , HMnO ₄ , HBr, HNO ₃ , HCl, HI, HClO ₃ , HClO ₄ , H ₃ PO ₄ , p-toluenesulfonic acid, triflic acid, carborane superacid, fluoroantimonic acid, acetic acid, citric acid, borane acid, diethylbarbituric acid, sodium benzenesulfonate, sodium dodecylbenzenesulfonate, But are not limited to, dioctyl sodium sulfosuccinate, perfluorobutanesulfonic acid, perfluorooctanesulfonic acid, perfluorononanoic acid, perfluorooctanoic acid, perfluorooctanoic acid, sodium acetate, sodium palmitate, sodium stearate, sodium tallowate, Na ₂ HPO ₄ , KH ₂ PO ₄ , sodium acetate, sodium citrate citrate), Characterized in that it comprises borax, KMnO ₄ , or K ₂ Cr ₂ O ₇ .
Gt;
The method according to claim 1,
Wherein the voltage of step 1 is in the range of 0.01 to 200 V,
Gt;
The method according to claim 1,
The dispersant may be a pyrene-based low molecular weight material; Cellulosic polymers; Cationic surfactants; Anionic surfactants; Gum arabic; n-Dodecyl bD-maltoside; Amphoteric surfactants; Polyvinylpyrrolidone type polymers; Polyethylene oxide type polymers; Ethylene oxide-propylene oxide copolymer; Tannic acid; Or a mixture of plural kinds of polyaromatic hydrocarbon oxides, wherein the mixture contains a polyaromatic hydrocarbon oxide having a molecular weight of 300 to 1000 in an amount of not less than 60% by weight,
Gt;
The method according to claim 1,
The solvent of the dispersion solution may be selected from the group consisting of water, N-methyl-2-pyrrolidone, acetone, N, N-dimethylformamide, DMSO, CHP, N-dodecyl-pyrrolidone ), Benzyl benzoate, N-octyl-pyrrolidone, dimethyl-imidazolidinone, cyclohexanone, dimethylacetamide, NMF (N-Methyl Formamide), bromobenzene, chloroform, chlorobenzene, benzonitrile , Quinoline, benzyl ether, ethanol, isopropyl alcohol, methanol, butanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxypropanol, tetrahydrofuran (THF), ethylene glycol, , Methyl ethyl ketone (butanone), alpha-terpineol, formic acid, ethyl acetate and acrylonitrile.
Gt;
The method according to claim 1,
Characterized in that the high-speed homogenization is carried out by stirring the dispersion solution at 3000 to 8000 rpm.
Gt;
The method according to claim 1,
Wherein the graphene precursor in the feed solution is peeled while passing through the fine flow path under application of a shear force to produce graphene.
Gt;
The method according to claim 1,
Characterized in that the fine flow path has a diameter of 50 to 300 mu m.
Gt;
The method according to claim 1,
Wherein the feed solution flows into the inlet portion of the high-pressure homogenizer under a pressure of 500 to 3000 bar and passes through the microchannel.
Gt;
The method according to claim 1,
Characterized in that the step 2 is further carried out 2 to 10 times.
Gt;

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