Large-area graphene film and rapid preparation method thereof

Abstract

The application provides a large-area graphene film and a rapid preparation method thereof, and belongs to the technical field of two-dimensional nanomaterials and inorganic film preparation. The preparation method comprises the following steps: adding graphene and an auxiliary agent into a solvent and uniformly mixing to obtain a graphene dispersion liquid; performing blade coating or suction filtration treatment on the graphene dispersion liquid, so that the graphene dispersion liquid is uniformly deposited on a polymer base film; performing drying treatment to obtain a polymer base film with an attached graphene layer; submerging the polymer base film with the attached graphene layer in a solution, so that the graphene layer in the polymer base film with the attached graphene layer is separated from the polymer base film and suspended on the surface of the solution, and the graphene layers are assembled to form a large-area graphene film. The method is based on the graphene dispersion liquid, a graphene conductive film is formed by blade coating or suction filtration, and then a large-area continuous graphene film is assembled on the surface of the solution under the action of the auxiliary agent, so that the production efficiency is high, the device is simple, the cost is low, and the method is suitable for industrialization.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of two-dimensional nanomaterials and inorganic thin film preparation, and particularly relates to a large-area graphene film and a rapid preparation method thereof. BACKGROUND

[0002] Graphene is a two-dimensional monolayer film with a hexagonal honeycomb structure of carbon atoms in sp 2 hybridization. As the first two-dimensional nanomaterial successfully prepared in the world, graphene has attracted extensive attention in the scientific community due to its unique structure and excellent physical and chemical properties such as optical, electrical, mechanical, etc. The conductivity of graphene is almost as high as that of a metal element, and its optical transmittance is as high as 97.7%. The preparation and film forming technology of high-conductivity and transparent graphene is the basic condition for promoting the application and industrialization of graphene in the fields of optoelectronic devices, supercapacitors, field emission, energy storage, etc., and the multifunctionality of graphene film has stimulated the research enthusiasm of researchers.

[0003] At present, the preparation methods of graphene are divided into "top-down" and "bottom-up" methods. The "top-down" method includes mechanical exfoliation, oxidation-reduction, supercritical fluid exfoliation and liquid phase exfoliation, etc., among which the liquid phase exfoliation is a direct and scalable method that can be applied to large-scale preparation and application; the "bottom-up" method includes chemical vapor deposition (CVD) method and epitaxial growth method, etc. The existing film forming technology of graphene film mainly includes solution coating, layer-by-layer assembly (LBL), CVD growth, etc. These methods have their own advantages and disadvantages: (1) Solution coating method is simple to operate and uses multiple substrates. However, graphene sheets in the solution are prone to uneven aggregation during drying, which sharply reduces the uniformity and conductivity, thermal conductivity, mechanical properties, etc. of the film. (2) The spin coating method can prepare large-area graphene films, but the thickness of the obtained graphene film is relatively thick and the stacking is disordered, which causes a significant decrease in conductivity. (2) The LBL method can design the film more accurately, but it needs to regulate the substrate and graphene interaction. In addition, the LBL method is time-consuming and still has the problem of uneven aggregation of graphene sheets induced by drying. (3) The CVD method is a method that can realize high-quality, large-area and continuous graphene film, but this method is expensive and the film thickness is thin, which is only suitable for electronic devices and other scene requirements. In addition, this method usually needs to transfer the graphene film grown on the catalytic metal substrate to the target substrate, which often introduces metal residues and causes structural damage during the transfer process, resulting in a decrease in the conductivity of the graphene film. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application aims to provide a large-area graphene film and a rapid preparation method thereof, which can rapidly assemble graphene sheets and form a large-area graphene film, is simple in operation, fast in film formation, green in environmental protection, high in conductivity of the conductive film, excellent in stability, wide in applicable substrate, greatly reduces the production cost of the graphene conductive film, and is conducive to promoting the industrialized production of the graphene film.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The present application provides a rapid preparation method of a large-area graphene film, comprising the following steps:

[0007] S1: adding graphene and an auxiliary agent into a solvent A and uniformly mixing to obtain a graphene dispersion liquid;

[0008] S2: performing blade coating or suction filtration treatment on the graphene dispersion liquid, so that the graphene dispersion liquid is uniformly deposited on a polymer base film, and performing drying treatment to obtain a polymer base film with an attached graphene layer;

[0009] S3: submerging the polymer base film with the attached graphene layer in a solvent B, so that the graphene layer in the polymer base film is separated from the polymer base film and suspended on the surface of the solvent B, and the graphene layer is assembled to form a large-area graphene film.

[0010] Further, in the S1, the mass ratio of the graphene to the auxiliary agent is 1:(0.05-10).

[0011] Further, in the S1, the auxiliary agent is a dispersing agent, and the auxiliary agent is one or more combinations of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, lauryl sulfosuccinic acid monodisodium, monododecyl phosphate potassium, a chloride salt and a hydroxide of a metal ion, tetramethylammonium chloride, tetrabutylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, ethanol, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, N-methylpyrrolidone, Tween-60 and polyvinylpyrrolidone.

[0012] Further, in the S1, the concentration of the graphene dispersion liquid is 0.05-5 mg / ml.

[0013] Further, in the S1, the solvent A is one or more combinations of methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide and N-methylpyrrolidone.

[0014] The application further relates to the polymer base film in the S2, wherein the polymer base film is any one of an acetate fiber resin film, a polyether sulfone film, a nylon film, a polyamide film, a polytetrafluoroethylene film, a polyvinylidene fluoride film, a nitrocellulose film or a porous aluminum oxide film.

[0015] The application further relates to the S2, wherein the drying treatment is performed at a temperature of 10-200 DEG C, a relative humidity of 10-95%, and for a time period of 1 min-2 h.

[0016] The application further relates to the S2, wherein the thickness of the graphene layer in the graphene layer-attached polymer base film is 1 nm-200 microns.

[0017] The application further relates to the S3, wherein the solvent B is one or more of the following: ammonia, methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N-methylformamide and N-methylpyrrolidone.

[0018] The application further provides a graphene film prepared by the method.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] The application provides a method for rapidly preparing a large-area graphene film.

[0021] The graphene film prepared by the method can be transferred to any substrate, and the method has the advantages of fast film-forming speed, simple process and good graphene film quality. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A scanning electron microscope image of the graphene film prepared by the application;

[0023] Figure 2 An optical microscope image of the graphene film prepared by the application. DETAILED DESCRIPTION

[0024] To enable persons skilled in the art to have a better understanding of the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have the usual meaning understood by those skilled in the art of the present application, and in the event of conflict, the definition in the specification shall prevail.

[0025] Theories and mechanisms described and disclosed herein, whether correct or not, should not be considered limiting on the scope of the present application, which can be practiced without regard to any particular theory or mechanism.

[0026] Herein, all features defined by numerical ranges or percentage ranges, such as numerical values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0027] Herein, unless otherwise specified, "comprise", "include", "contain", "have" or similar words are intended to cover the meaning of "consist of" and "consist essentially of", for example, "A comprises a" covers the meaning of "A comprises a and other" and "A comprises only a".

[0028] Herein, for the sake of brevity, all possible combinations of the various technical features in the various embodiments or examples are not described. Therefore, the various technical features in the various embodiments or examples can be combined in any manner as long as there is no contradiction, and all possible combinations should be considered as falling within the scope of the present specification.

[0029] The present application provides a large-area graphene film and a rapid preparation method thereof.

[0030] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not intended to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms should also fall within the scope of the claims appended to the present application.

[0031] The following examples use conventional apparatus in the art. The experimental methods in the following examples, unless otherwise specified, are usually carried out under conventional conditions, or under the conditions recommended by the manufacturer. In the following examples, various raw materials are used, unless otherwise specified, and conventional commercially available products are used, which are conventional specifications in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0032] The application discloses a method for rapidly preparing a large-area graphene film. First, graphene and an auxiliary agent are added into a solvent A, and a graphene dispersion liquid is formed after ultrasonic or stirring treatment. Then, the graphene dispersion liquid is uniformly deposited on a polymer base film through scraping coating or suction filtration, and drying treatment is performed under certain temperature and humidity. Subsequently, the polymer film is slowly immersed in a solvent B, and at this time, the graphene on the surface of the polymer base film is suspended and assembled to form a large-area graphene film on the surface of the solvent B under the action of the auxiliary agent.

[0033] The large-area graphene film disclosed by the application can be transferred to any substrate, the preparation method has the advantages of fast film forming speed, simple process and good graphene film quality, and has wide application prospects in the fields of conductive coating, new materials and electronic devices.

[0034] The specific steps of the method for rapidly preparing a large-area graphene film are as follows:

[0035] Step one: graphene and an auxiliary agent serving as a dispersant are added into a solvent A at a mass ratio of 1:(0.05-10), and ultrasonic or stirring treatment is performed for 5 min to 2 h to obtain a graphene dispersion liquid with a concentration of 0.05-5 mg / ml;

[0036] Step two: the graphene dispersion liquid is used as a basis to form a graphene conductive film through scraping coating or suction filtration;

[0037] The obtained graphene dispersion liquid is uniformly deposited on a polymer base film through scraping coating or suction filtration, and drying treatment is performed under certain temperature and humidity for 1 min to 10 h to obtain a polymer base film with a graphene layer of a certain thickness; the certain temperature and humidity refer to a temperature of 10-200 DEG C and a humidity of 10-95% of relative humidity, preferably a temperature of 25-50 DEG C and a humidity of normal humidity to 90%; the graphene layer of a certain thickness refers to a layer thickness of 1 nm to 200 microns.

[0038] Step three: a large-area continuous graphene film is assembled on the surface of the solution under the action of the auxiliary agent;

[0039] The polymer base film with the graphene layer is slowly immersed in a solvent B, and at this time, the graphene layer is separated from the polymer base film and suspended on the surface of the solvent B and assembled to form a large-area graphene film under the action of the auxiliary agent and the solvent B.

[0040] In particular, the suspended large-area graphene film can be directly transferred to various substrate layers.

[0041] Preferably, the dispersant in step one is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, lauryl sulfonate succinate monosodium, potassium monododecyl phosphate, chlorides and hydroxides of various ions (sodium, potassium, lithium, magnesium, calcium, aluminum ions), alkylammonium (tetramethylammonium chloride, tetrabutylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride), ethanol, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, N-methylpyrrolidone, Tween-60, polyvinylpyrrolidone. The solvent A is one or more of methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide or N-methylpyrrolidone.

[0042] Further, the dispersant is one or more of sodium dodecyl benzene sulfonate, tetramethylammonium chloride, ethanol, water, N,N-dimethylformamide, N-methylpyrrolidone.

[0043] The polymer-based film in step two refers to an acetate fiber resin film, a polyether sulfone film, a nylon film, a polyamide film, a polytetrafluoroethylene film, a polyvinylidene fluoride film, a nitrocellulose film or a porous aluminum oxide film.

[0044] The solvent B in step three is one or more of ammonia, methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, N-methylpyrrolidone.

[0045] The graphene film prepared by the method of the present application has a wide range of suitable substrates, and can be formed on smooth substrates as well as rough structure surfaces. The film forming process is simple and can effectively shorten the production cycle.

[0046] Example 1

[0047] 10 mg of graphene was dispersed in 50 ml of ethanol solution, and 10 mg of tetramethylammonium chloride was added as an auxiliary agent. After ultrasonic treatment for 1 h, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. The prepared solution was deposited on a 10 cm x 10 cm polyether sulfone film by means of scraping. The film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 10 min. Then the graphene-loaded polyether sulfone film was slowly inserted into a methanol solution, at which time the graphene layer was peeled off from the surface of the polyether sulfone film and assembled into a suspension on the surface of the methanol solution to form a graphene film with an area of 100 cm 2 After being transferred to a silica wafer, the film was tested to have a thickness of 15 nm (as shown in Figure 1 Figure 2) and a conductivity of 70 S cm.-1 .

[0048] Example 2

[0049] The 10 mg graphene was dispersed in 50 ml ethanol solution, and then 50 mg of N,N-dimethylformamide was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. 5 ml of the above graphene dispersion solution was deposited on a 20 cm 2 nylon film by suction filtration, and the film was dried in an environment with a relative humidity of 50% and a temperature of 20°C for 1 min. Then the graphene-loaded nylon film was slowly inserted into water, at which time the graphene layer was peeled off from the surface of the nylon film and assembled into a suspension on the surface of the aqueous solution to form a graphene film with an area of 20 cm 2 . After being transferred to a silica wafer, the film was tested to have a thickness of 40 nm and a conductivity of 101S cm -1 .

[0050] Example 3

[0051] The 10 mg graphene was dispersed in 50 ml ethanol solution, and then 0.5 mg of the auxiliary agent sodium dodecyl benzene sulfonate was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. The prepared solution was deposited on a 10 cm x 10 cm polyether sulfone film by means of scraping, and the film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 10 min. Then the graphene-loaded polyether sulfone film was slowly inserted into a mixed solvent of ethanol and water (ethanol: water = 1:2), at which time the graphene layer was peeled off from the surface of the polyether sulfone film and assembled into a suspension on the surface of the mixed solution of ethanol and water to form a graphene film with an area of 100 cm 2 . After being transferred to a silica wafer, the film was tested to have a thickness of 620 nm and a conductivity of 30 S cm -1 .

[0052] Example 4

[0053] The 100 mg graphene was dispersed in 50 ml of N-methyl pyrrolidone solution, and then 20 mg of the auxiliary agent aluminum chloride was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 2 mg / ml was obtained. The prepared solution was deposited on a 10 cm x 10 cm polytetrafluoroethylene film by means of scraping, and the film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 10 min. Then the graphene-loaded polytetrafluoroethylene film was slowly inserted into an aqueous solution, at which time the graphene layer was peeled off from the surface of the polytetrafluoroethylene film and assembled into a suspension on the surface of the aqueous solution to form a graphene film with an area of 100 cm 2 . After being transferred to a silica wafer, the film was tested to have a thickness of 10 μm and a conductivity of 200 S cm -1 .

[0054] Example 5

[0055] 10 mg graphene was dispersed in 50 ml ethanol solution, then added N,N- dimethylformamide 100 mg, after 1 h ultrasonic treatment, the graphene dispersion solution with concentration of 0.2 mg / ml was obtained. 5 ml graphene dispersion solution was taken and deposited on 20 cm 2 polyvinylidene fluoride membrane by suction filtration, and dried for 1 min in the normal temperature and humidity environment. Then the graphene loaded polyvinylidene fluoride membrane was slowly inserted into water, at this time the graphene layer was peeled off from the surface of the polyvinylidene fluoride membrane and assembled into a graphene film with an area of 20 cm 2 on the surface of the water solution. After being transferred to a silica sheet, the film thickness was tested to be 35 nm, and the conductivity was 165 S cm -1 .

[0056] Example 6

[0057] 10 mg graphene was dispersed in 200 ml ethanol solution, then added auxiliary agent tetramethylammonium chloride 0.5 mg, after 1 h ultrasonic treatment, the graphene dispersion solution with concentration of 0.05 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyether sulfone membrane by scraping, and the membrane was dried for 50 min in the environment of relative humidity 50% and temperature 50°C. Then the graphene loaded polyether sulfone membrane was slowly inserted into N-methyl formamide solution, at this time the graphene layer was peeled off from the surface of the polyether sulfone membrane and assembled into a graphene film with an area of 10 cm 2 on the surface of the N-methyl formamide solution. After being transferred to a silica sheet, the film thickness was tested to be 10 nm, and the conductivity was 40 S cm -1 .

[0058] Example 7

[0059] 10 mg graphene was dispersed in 2 ml ethanol solution, then added auxiliary agent N-methyl formamide 50 mg, after 1 h ultrasonic treatment, the graphene dispersion solution with concentration of 5 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyether sulfone membrane by scraping, and the membrane was dried for 50 min in the environment of relative humidity 50% and temperature 50°C. Then the graphene loaded polyether sulfone membrane was slowly inserted into N,N-dimethylformamide solution, at this time the graphene layer was peeled off from the surface of the polyether sulfone membrane and assembled into a graphene film with an area of 10 cm 2 on the surface of the N,N-dimethylformamide solution. After being transferred to a silica sheet, the film thickness was tested to be 100 μm, and the conductivity was 211 S cm -1 .

[0060] Example 8

[0061] The 10 mg graphene was dispersed in 200 ml ethanol solution, and then 100 mg of auxiliary agent tetramethylammonium chloride was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.05 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyether sulfone film by means of scraping, and the film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 50 min. Then the graphene-loaded polyether sulfone film was slowly inserted into an N,N-dimethylformamide solution, at which time the graphene layer was peeled off from the surface of the polyether sulfone film and assembled to form a graphene film with an area of 10 cm 2 on the surface of the N,N-dimethylformamide solution. After being transferred to a silicon dioxide sheet, the film was tested to have a thickness of 1 nm.

[0062] Example 9

[0063] The 10 mg graphene was dispersed in 2 ml ethanol solution, and then 50 mg of auxiliary agent N-methylpyrrolidone was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 5 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyether sulfone film by means of scraping, and the film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 50 min. Then the graphene-loaded polyether sulfone film was slowly inserted into an ethanol solution, at which time the graphene layer was peeled off from the surface of the polyether sulfone film and assembled to form a graphene film with an area of 10 cm 2 on the surface of the ethanol solution. After being transferred to a silicon dioxide sheet, the film was tested to have a thickness of 200 μm.

[0064] Example 10

[0065] The 10 mg graphene was dispersed in 50 ml methanol solution, and then 10 mg of auxiliary agent sodium dodecyl sulfate was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. The prepared solution was deposited on a 10 cm x 10 cm cellulose acetate film by means of suction filtration, and the film was dried in an environment with a relative humidity of 50% and a temperature of 10°C for 10 min. Then the graphene-loaded cellulose acetate film was slowly inserted into an ammonia solution, at which time the graphene layer was peeled off from the surface of the cellulose acetate film and assembled to form a graphene film with an area of 100 cm 2 on the surface of the ammonia solution.

[0066] Example 11

[0067] The 10 mg graphene was dispersed in 50 ml isopropanol solution, and then 50 mg of auxiliary agent lauryl sulfosuccinic acid monosodium was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. 5 ml of the above graphene dispersion solution was deposited on a 20 cm2 The nylon membrane was dried for 1 minute in an environment with a relative humidity of 60% and a temperature of 200°C. Then, the graphene-loaded nylon membrane was slowly inserted into water. At this point, the graphene layer peeled off from the surface of the nylon membrane and assembled and suspended on the surface of the aqueous solution, forming a 20 cm² area. 2 Graphene film.

[0068] Example 12

[0069] 10 mg of graphene was dispersed in 50 ml of acetone solution, and 1 mg of potassium monododecyl phosphate was added as an auxiliary agent. After ultrasonic treatment for 1 h, a graphene dispersion with a concentration of 0.2 mg / ml was obtained. The prepared solution was deposited onto a 10 cm × 10 cm polyethersulfone membrane using a blade coating method. The membrane was dried in an environment with a relative humidity of 50% and a temperature of 50 °C for 2 h. Subsequently, the graphene-loaded polyethersulfone membrane was slowly immersed in a mixed solvent of ethanol and water (ethanol:water = 1:2). At this time, the graphene layer peeled off from the surface of the polyethersulfone membrane and assembled and suspended on the surface of the ethanol and water mixed solution to form a 100 cm² area. 2 Graphene film.

[0070] Example 13

[0071] 100 mg of graphene was dispersed in 50 ml of acetonitrile solution, and 20 mg of aluminum chloride was added as an auxiliary agent. After ultrasonic treatment for 1 hour, a graphene dispersion with a concentration of 2 mg / ml was obtained. The prepared solution was deposited onto a 10 cm × 10 cm polytetrafluoroethylene (PTFE) membrane using a blade coating method. The membrane was dried at 50% relative humidity and 50°C for 60 minutes. Subsequently, the PTFE membrane loaded with graphene was slowly immersed in an isopropanol solution. At this time, the graphene layer peeled off from the surface of the PTFE membrane and assembled and suspended on the surface of the isopropanol solution to form a 100 cm² area. 2 Graphene film.

[0072] Example 14

[0073] 10 mg of graphene was dispersed in 50 ml of tetrahydrofuran solution, and then 50 mg of tetrabutylammonium chloride was added as an auxiliary agent. After ultrasonic treatment for 1 hour, a graphene dispersion with a concentration of 0.2 mg / ml was obtained. 5 ml of the above graphene dispersion was deposited for 20 cm using vacuum filtration. 2 The polyvinylidene fluoride (PVDF) membrane was dried at room temperature and humidity for 30 minutes. Then, the PVDF membrane loaded with graphene was slowly inserted into acetone. At this point, the graphene layer peeled off from the PVDF membrane surface and assembled and suspended on the acetone solution surface, forming a 20 cm² area. 2 Graphene film.

[0074] Example 15

[0075] The 10 mg graphene was dispersed in 200 ml of n-hexane solution, and then 0.5 mg of the auxiliary agent dodecyltrimethylammonium chloride was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.05 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm nitrocellulose membrane by means of scraping, and the membrane was dried in an environment with a relative humidity of 10% and a temperature of 100°C for 50 min. Then the graphene-loaded nitrocellulose membrane was slowly inserted into an acetonitrile solution, at which time the graphene layer was peeled off from the surface of the nitrocellulose membrane and assembled into a suspension on the surface of the acetonitrile solution to form a graphene film with an area of 10 cm 2 .

[0076] Example 16

[0077] The 10 mg graphene was dispersed in 2 ml of dimethyl sulfoxide solution, and then 50 mg of the auxiliary agent tetradecyltrimethylammonium chloride was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 5 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm porous alumina membrane by means of scraping, and the membrane was dried in an environment with a relative humidity of 70% and a temperature of 10°C for 50 min. Then the graphene-loaded porous alumina membrane was slowly inserted into a tetrahydrofuran solution, at which time the graphene layer was peeled off from the surface of the porous alumina membrane and assembled into a suspension on the surface of the tetrahydrofuran solution to form a graphene film with an area of 10 cm 2 .

[0078] Example 17

[0079] The 10 mg graphene was dispersed in 200 ml of N,N-dimethylformamide solution, and then 100 mg of the auxiliary agent ethanol was added. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.05 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyamide membrane by means of scraping, and the membrane was dried in an environment with a relative humidity of 80% and a temperature of 200°C for 50 min. Then the graphene-loaded polyamide membrane was slowly inserted into a n-hexane solution, at which time the graphene layer was peeled off from the surface of the polyamide membrane and assembled into a suspension on the surface of the n-hexane solution to form a graphene film with an area of 10 cm 2 .

[0080] Example 18

[0081] A 10 mg graphene was dispersed in 2 ml N,N-dimethylformamide solution, and 50 mg of dimethyl sulfoxide was added as an auxiliary agent. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 5 mg / ml was obtained. The prepared solution was deposited on a 2 cm x 5 cm polyether sulfone film by means of scraping, and the film was dried in an environment with a relative humidity of 95% and a temperature of 150°C for 50 min. Subsequently, the graphene-loaded polyether sulfone film was slowly inserted into the dimethyl sulfoxide solution, at which time the graphene layer was peeled off from the surface of the polyether sulfone film and assembled into a suspension on the surface of the dimethyl sulfoxide solution to form a graphene film with an area of 10 cm 2

[0082] Comparative Example 1

[0083] A 10 mg graphene was dispersed in 50 ml water solution without any auxiliary agent, and after 1 h of ultrasonic treatment, a graphene-water mixed solution with a concentration of 0.2 mg / ml was obtained. At this time, the graphene was aggregated in the water and did not form a uniform dispersion state. The prepared solution was deposited on a 10 cm x 10 cm polyether sulfone film by means of scraping, and the film was dried in an environment with a relative humidity of 50% and a temperature of 50°C for 10 min. Subsequently, the graphene-loaded polyether sulfone film was slowly inserted into the methanol solution, at which time the graphene layer was partially peeled off from the surface of the polyether sulfone film and could not form a continuous graphene film.

[0084] Comparative Example 2

[0085] A 10 mg graphene was dispersed in 50 ml ethanol solution, and 10 mg of tetramethylammonium chloride was added as an auxiliary agent. After 1 h of ultrasonic treatment, a graphene dispersion solution with a concentration of 0.2 mg / ml was obtained. At this time, the prepared solution was deposited on a 10 cm x 10 cm polyether sulfone film by means of scraping, and the graphene layer did not combine well with the polyether sulfone without drying treatment. Subsequently, the graphene-loaded polyether sulfone film was slowly inserted into the methanol solution, at which time the graphene was directly dispersed into the methanol solution due to the presence of a large amount of solvent A on the surface of the polyether sulfone, and could not form a film on the surface.

[0086] Comparative Example 3

[0087] A 100 mg graphene was dispersed in 5 ml ethanol solution, and 50 mg of water was added. After 1 h of ultrasonic treatment, a graphene solution with a concentration of 20 mg / ml was obtained. At this time, the solution concentration was too high, and the graphene coexisted in the solution in the form of partial precipitation and partial dispersion. 5 ml of the above graphene dispersion solution was deposited on a 20 cm 2 ​The nylon membrane was dried for 0.2 minutes in an environment with a relative humidity of 50% and a temperature of 20°C. Then, the graphene-loaded nylon membrane was slowly immersed in water. At this point, the graphene layer could only partially peel off from the surface of the nylon membrane and was discontinuous. After being transferred to a silicon dioxide wafer, the area of ​​the intact membrane was only 2.2 cm². 2 The conductivity decreased to 1.2 S cm⁻¹. -1 .

[0088] Comparative Example 4

[0089] 10 mg of graphene was dispersed in 500 ml of ethanol solution, and then 50 mg of water was added. After ultrasonic treatment for 1 hour, a graphene dispersion with a concentration of 0.02 mg / ml was obtained. 5 ml of the above graphene dispersion was deposited for 20 cm using vacuum filtration. 2 The polyvinylidene fluoride (PVDF) membrane was dried in a normal temperature and humidity environment for 1 minute. Then, the PVDF membrane loaded with graphene was slowly inserted into a hydrochloric acid solution. At this point, the membrane was damaged and fractured, and the graphene layer could not be suspended on the surface of the hydrochloric acid solution.

[0090] like Figure 1 As shown in the scanning electron microscope image of the graphene film prepared in Example 1, the graphene sheets inside the film are clearly visible and overlap each other, forming a continuous film with a good charge transport network. Figure 2 As shown in the optical microscope image of the graphene film prepared in Example 2, it can be seen from the optical microscope image that the obtained graphene film is still continuous and unbroken at the micrometer scale, and the preparation and transfer process did not damage the film structure.

[0091] Through comparison of examples and comparative examples, the preparation method of the present invention enables the rapid assembly of graphene sheets to form large-area graphene films. The method is simple to operate, has a fast film formation speed, is green and environmentally friendly, and the conductive film has high conductivity, excellent stability, and a wide range of applicable substrates. It greatly reduces the production cost of graphene conductive films and is conducive to promoting the industrial production of graphene films.

[0092] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for rapidly preparing large-area graphene film, characterized in that, The method comprises the following steps: S1: adding graphene and an auxiliary agent into solvent A and mixing to obtain a graphene dispersion; the mass ratio of the graphene to the auxiliary agent is 1:(0.05-10); the auxiliary agent is a dispersing agent, and the auxiliary agent is one of aluminum chloride and tetrabutylammonium chloride; the concentration of the graphene dispersion is 0.05-5 mg / ml; S2: performing blade coating or suction filtration treatment on the graphene dispersion to uniformly deposit the graphene dispersion on a polymer base film, and performing drying treatment to obtain a polymer base film with an attached graphene layer; the temperature of the drying treatment is 10-200 DEG C; the relative humidity of the drying treatment is 10-95%; in the S2, the thickness of the graphene layer in the polymer base film with the attached graphene layer is 1 nm-200 μm; S3: submerging the polymer base film with the attached graphene layer in solvent B, and separating the graphene layer in the polymer base film with the attached graphene layer from the polymer base film and suspending the graphene layer on the surface of the solvent B, and assembling the graphene layer to form a large-area graphene film.

2. The method according to claim 1, wherein the graphene film is prepared in a large area. In the S1, the solvent A is one or a combination of multiple of methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide and N-methylpyrrolidone.

3. The method of claim 1, wherein the graphene film is formed on a substrate. In the S2, the polymer base film is any one of cellulose acetate resin film, polyethersulfone film, nylon film, polyamide film, polytetrafluoroethylene film, polyvinylidene fluoride film, nitrocellulose film or porous alumina film. 4.The method of claim 1, wherein the graphene film is formed on a substrate. In the S3, the solvent B is one or a combination of multiple of ammonia, methanol, ethanol, water, isopropanol, acetone, acetonitrile, tetrahydrofuran, n-hexane, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, N-methylpyrrolidone.

5. A graphene film prepared by the method for rapidly preparing a large-area graphene film according to any one of claims 1-4.

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