CN111732094A - Method for preparing graphene through ultrasonic-assisted supercritical liquid phase stripping - Google Patents
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Abstract
The invention provides a method for preparing graphene by ultrasonic-assisted supercritical liquid phase stripping, which comprises the following steps: taking graphite as a raw material, and carrying out carbon dioxide supercritical treatment and ultrasonic treatment on the graphite to obtain the graphene. The method has the advantages of simple process, low cost, abundant raw material resources, easy large-scale production, high quality of the obtained graphene and good industrial application prospect.
Description
Technical Field
The invention relates to the technical field of graphene preparation, in particular to a method for preparing graphene by ultrasonic-assisted supercritical liquid phase stripping.
Background
Graphene was found for 16 years to date, and slowly enters the initial stage of industrialization after a long laboratory development stage. The large-scale industrialization necessarily requires a mature method for preparing graphene in large quantities. In fact, there are many methods for preparing graphene, but they mainly include two types: the Top-Down method and the Bottom-up method.
The Top-Down method generally uses graphite as a raw material, increases the graphite layer spacing by various physical or chemical means, and further strips the graphite to obtain graphene. Such methods mainly include redox methods, mechanical exfoliation methods, and liquid phase intercalation exfoliation methods. The oxidation-reduction method is to oxidize graphite by using strong oxidants such as sulfuric acid, potassium permanganate and the like so as to increase the graphite interlayer spacing, obtain graphene oxide through ultrasonic stripping, and then obtain graphene through high-temperature reduction. The mechanical exfoliation method is to physically treat graphite using some special equipment to obtain graphene. The liquid phase intercalation stripping is to use a specific organic solvent to intercalate graphite so as to obtain graphene.
The Bottom-up method generally uses small molecule gas, organic matter or silicon carbide as raw materials, and removes non-carbon elements through a certain physical and chemical process, so that carbon atoms are rearranged, and graphene is obtained. Such methods mainly include chemical vapor deposition, epitaxial growth, and chemical synthesis. In the chemical vapor deposition method, carbon-containing small molecule gas is generally used as a raw material, and under the catalytic action of metals such as copper and nickel, the small molecules are decomposed on the surface of a catalyst, and carbon atoms are rearranged to form a graphene structure. The epitaxial growth method comprises breaking silicon-carbon bond in silicon carbide under high temperature and high vacuum conditions, sublimating silicon atoms from the surface, and rearranging the carbon atoms enriched on the surface to form sp2A hybridized carbon-carbon bond. The chemical synthesis method generally uses an organic compound as a raw material, and the organic compound is pyrolyzed at high temperature and high pressure to form graphene.
Among these preparation methods, environmental pollution is caused in the redox preparation process, and the chemical vapor deposition method and the epitaxial growth method are expensive in equipment and high in cost. The physical mechanical stripping method is environment-friendly due to low cost of raw materials, and is a promising industrialization method. The previous reported results are generally carried out by adopting a single mechanical stripping means, and a new method for preparing graphene by combining mechanical stripping is needed in order to improve the stripping efficiency and the product quality.
It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
The invention provides a method for preparing graphene by ultrasonic-assisted supercritical liquid phase stripping, which aims to overcome at least one defect of the prior art and solve the problems of high cost, low product quality and the like of the conventional graphene preparation process.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for preparing graphene by ultrasonic-assisted supercritical liquid phase stripping, which comprises the steps of taking graphite as a raw material, and carrying out carbon dioxide supercritical treatment and ultrasonic treatment on the graphite to obtain the graphene.
According to one embodiment of the invention, the method further comprises the steps of adding a first solvent and a first dispersing agent into the graphite, and fully mixing to obtain a first dispersion liquid as a raw material; the first solvent is selected from one or more of water, N-methyl pyrrolidone and ethanol, the first dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, lecithin, polyvinylpyrrolidone, polyvinyl alcohol, sodium lignin sulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid and polysorbate, the mass ratio of the graphite to the first solvent is 1: 10-200, and the mass ratio of the graphite to the first dispersing agent is 200-5: 1.
According to one embodiment of the invention, the method comprises the following steps: placing the raw materials in a reaction kettle connected with ultrasonic equipment; introducing carbon dioxide into the reaction kettle, adjusting the pressure of the reaction kettle to 8 MPa-100 MPa, the temperature to 35-500 ℃, setting the ultrasonic power to 500W-3000W, and keeping for 0.1-10 h for reaction.
According to an embodiment of the present invention, further comprising: and adding a second solvent and a second dispersing agent into the reacted product, fully mixing to obtain a second dispersion solution, homogenizing the second dispersion solution under the pressure of 100-300 MPa, and drying to obtain the graphene.
According to one embodiment of the invention, the second solvent is selected from one or more of water, N-methyl pyrrolidone and ethanol, and the second dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, cetyltrimethyl ammonium bromide, lecithin, polyvinylpyrrolidone, polyvinyl alcohol, sodium lignin sulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid, and polysorbate; the mass ratio of the graphite to the second solvent is 1: 10-200, and the mass ratio of the graphite to the second dispersing agent is 200-5: 1.
According to one embodiment of the present invention, the homogenization treatment is repeated 3 to 6 times, and the time for each homogenization treatment is 5 to 50 min.
According to one embodiment of the invention, the method further comprises the steps of carrying out secondary ultrasonic treatment after homogenizing treatment, and drying to obtain graphene; wherein the power of the secondary ultrasonic treatment is 500W-3000W, and the time is 1 h-5 h.
According to one embodiment of the present invention, the graphite is one or more of natural graphite, artificial graphite and expanded graphite.
According to one embodiment of the present invention, the graphite is in a powder form and has a particle size of 1 μm to 100. mu.m.
According to one embodiment of the present invention, the number of graphene layers is 5 to 10.
According to the technical scheme, the invention has the beneficial effects that:
the invention provides a novel method for preparing graphene by utilizing ultrasonic-assisted supercritical liquid phase stripping, and the obtained graphene is high in quality and good in electric conduction and heat conduction performance. The method has the advantages of simple process, low cost, abundant raw material resources, easy large-scale production and good industrial application prospect.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
Fig. 1 is an atomic force microscope image of graphene prepared in example 1.
Fig. 2 is an atomic force microscope image of graphene prepared in example 2.
Fig. 3 is an atomic force microscope image of graphene prepared in example 3.
Fig. 4 is an atomic force microscope image of graphene prepared in example 4.
Fig. 5 is an atomic force microscope image of graphene prepared in example 5.
Detailed Description
The following presents various embodiments or examples in order to enable those skilled in the art to practice the invention with reference to the description herein. These are, of course, merely examples and are not intended to limit the invention. The endpoints of the ranges and any values disclosed in the present application are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to yield one or more new ranges of values, which ranges of values should be considered as specifically disclosed herein.
The invention provides a method for preparing graphene by ultrasonic-assisted supercritical liquid phase stripping, which comprises the steps of taking graphite as a raw material, and carrying out carbon dioxide supercritical treatment and ultrasonic treatment on the graphite to obtain the graphene.
According to the invention, the problems of high cost, low product quality and the like of the existing graphene preparation process are solved, and therefore, the inventor of the invention finds that high-quality graphene with good electric and heat conduction properties can be efficiently obtained by combining carbon dioxide supercritical treatment and ultrasonic treatment, namely, carrying out liquid phase stripping on graphite by using an ultrasonic-assisted supercritical method. The method has the advantages of simple process, low cost, rich raw material resources and good industrial application prospect.
The method for preparing graphene by ultrasonic-assisted supercritical liquid phase exfoliation according to an embodiment of the present invention is specifically described below.
First, graphite is provided as a raw material. Wherein the graphite may be natural graphite, artificial graphite, expanded graphite, etc., or a combination thereof, to which the present invention is not limited. Graphite powder having a particle size of 1 to 100 μm, preferably 1 to 10 μm is preferably used as the graphite.
Placing raw material graphite in a reaction kettle connected with ultrasonic equipment, introducing carbon dioxide into the reaction kettle, and adjusting the pressure of the reaction kettle to be 8 MPa-100 MPa, such as 8MPa, 10MPa, 15MPa, 20MPa, 50MPa, 70MPa and the like, preferably 10 MPa-50 MPa; the temperature is 35 ℃ to 500 ℃, for example, 35 ℃, 38 ℃, 50 ℃, 80 ℃, 100 ℃, 150 ℃, and the like, preferably 50 ℃ to 300 ℃, and the ultrasonic power is set to be 500W to 3000W, for example, 500W, 700W, 750W, 800W, 900W, 1000W, 2500W, and the like, preferably 1000W to 2000W, and the temperature is maintained for 0.1h to 10h, for example, 0.1h, 1h, 2h, 4h, 6h, 8h, and the like, preferably 0.5h to 5 h. At the moment, the graphite can be stripped in a liquid phase under the action of supercritical fluid carbon dioxide in the reaction kettle, so that graphene is obtained, the stripping effect of the graphite is further improved in a synergistic manner in an ultrasonic-assisted mode, the reaction time is greatly shortened, and meanwhile, the uniformly distributed multilayer graphene can be obtained. Generally, the number of graphene layers obtained by the method of the present invention is about 5 to 10.
According to the present invention, a uniformly dispersed graphite solution can be used as a raw material in the aforementioned method. Specifically, a first solvent and a first dispersant are added to graphite and sufficiently mixed to obtain a first dispersion, and the first dispersion is used as a raw material to perform carbon dioxide supercritical treatment and ultrasonic treatment.
Wherein, the first solvent is selected from one or more of water, N-methyl pyrrolidone and ethanol, and the water is preferably deionized water. The first dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, hexadecyl trimethyl ammonium bromide, lecithin, polyvinylpyrrolidone, polyvinyl alcohol, sodium lignosulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid and polysorbate, and the mass ratio of the graphite to the first solvent is 1: 10-200, for example, 1:10, 1:20, 1:30, 1:60, 1:80, 1:100, 1:130, 1:180 and the like, preferably 1: 20-200; the mass ratio of the graphite to the first dispersant is 200 to 5:1, for example, 5:1, 10:1, 15:1, 20:1, 38:1, 50:1, 65:1, 70:1, 80:1, 150:1, and the like, and preferably 20:1 to 5: 1.
Further, the method further comprises the step of further homogenizing the product obtained after the ultrasonic-assisted supercritical treatment, so that the stripping rate of graphite is further improved, and the yield of graphene is improved.
Specifically, after the supercritical reaction is completed, a pressure release valve of the reaction kettle is opened, the material is collected while instantly releasing the pressure, a second solvent and a second dispersing agent are added to the collected material and fully mixed to obtain a second dispersion liquid, the second dispersion liquid is subjected to high-pressure homogenization treatment at a pressure of 100MPa to 300MPa, for example, 100MPa, 120MPa, 210MPa, 250MPa, 280MPa, and preferably 100MPa to 200MPa, and then dried to obtain the graphene powder, wherein the drying manner may be drying or freeze-drying. In some embodiments, the homogenization treatment is repeated 3-6 times, and the time for each homogenization treatment is 5-50 min.
The first solvent is one or more selected from water, N-methyl pyrrolidone and ethanol, and the water is preferably deionized water. The first dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, hexadecyl trimethyl ammonium bromide, lecithin, polyvinylpyrrolidone, polyvinyl alcohol, sodium lignosulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid and polysorbate, and the mass ratio of the graphite to the first solvent is 1: 10-200, for example, 1:10, 1:20, 1:30, 1:60, 1:80, 1:100, 1:130, 1:180 and the like, preferably 1: 20-200; the mass ratio of the graphite to the first dispersant is 200 to 5:1, for example, 5:1, 10:1, 15:1, 20:1, 38:1, 50:1, 65:1, 70:1, 80:1, 150:1, and the like, and preferably 20:1 to 5: 1.
Furthermore, in order to obtain high-quality graphene with good dispersibility and higher yield, the invention also comprises secondary ultrasonic treatment after homogenization treatment, and graphene is obtained after drying, wherein the drying method can still be freeze-drying or drying. Wherein the power of the secondary ultrasonic treatment is 500W-3000W, such as 500W, 700W, 750W, 800W, 900W, 1000W, 2500W and the like, preferably 1000W-2000W; the secondary ultrasonic treatment time is 1h to 5h, for example, 1h, 3h, 4h, 5h and the like.
In conclusion, the method can efficiently obtain the high-quality graphene with good electric conductivity and heat conductivity by adopting the ultrasonic-assisted supercritical liquid phase stripping method, and has the advantages of simple process, low cost, abundant raw material resources, easiness for large-scale production and good industrial application prospect.
The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto. Unless otherwise specified, reagents, materials and the like used in the present invention are commercially available.
Example 1
1) 1kg of expanded graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to be 30MPa, raising the temperature of the reaction kettle to 50 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 2000W, and the holding time is 1 h. And opening the pressure release valve, and collecting the material while releasing the pressure instantly to obtain the graphene powder.
Fig. 1 is an atomic force microscope image of graphene prepared in example 1, and the number of graphene layers is about 10 as shown in fig. 1.
Example 2
1) 1kg of expanded graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to be 30MPa, raising the temperature of the reaction kettle to 50 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 2000W, and the holding time is 1 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 30kg of deionized water and 0.2kg of polyvinylpyrrolidone to obtain a dispersion liquid, placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 100MPa, and repeatedly carrying out homogenization treatment for 5 times, and the treatment time is 30min each time; and freeze-drying the homogenized dispersion liquid to obtain graphene powder.
Fig. 2 is an atomic force microscope image of the graphene prepared in example 2, and the number of graphene layers is about 9 as shown in fig. 2.
Example 3
1) 1kg of expanded graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to be 30MPa, raising the temperature of the reaction kettle to 50 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 2000W, and the holding time is 1 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 30kg of deionized water and 0.2kg of polyvinylpyrrolidone to obtain a dispersion liquid, placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 100MPa, and repeatedly carrying out homogenization treatment for 5 times, and the treatment time is 30min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 2000W, the ultrasonic time is 1h, and freeze-drying after ultrasonic treatment to obtain graphene powder.
Fig. 3 is an atomic force microscope image of the graphene prepared in example 3, and the number of layers of the graphene is about 5 as shown in fig. 3.
Example 4
1) 1kg of natural graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to 20MPa, raising the temperature of the reaction kettle to 80 ℃, and turning on an ultrasonic machine, wherein the ultrasonic power is 1600W, and the holding time is 2 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 20kg of N-methyl pyrrolidone and 0.1kg of sodium dodecyl sulfate to obtain a dispersion liquid, and placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 150MPa, and the homogenization treatment is repeatedly carried out for 4 times, and the treatment time is 20min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 1000W, the ultrasonic time is 2h, and drying after ultrasonic treatment to obtain graphene powder.
Fig. 4 is an atomic force microscope image of the graphene prepared in example 4, and the number of graphene layers is about 8 as shown in fig. 4.
Example 5
1) 1kg of artificial graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to 40MPa, raising the temperature of the reaction kettle to 60 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 1500W, and the holding time is 2 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 30kg of ethanol and 0.15kg of sodium dodecyl benzene sulfonate to obtain a dispersion liquid, and placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 200MPa, and the homogenization treatment is repeatedly carried out for 3 times, and the treatment time is 30min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 2000W, the ultrasonic time is 1h, and drying after ultrasonic treatment to obtain graphene powder.
Fig. 5 is an atomic force microscope image of the graphene prepared in example 5, and the number of graphene layers is about 8 as shown in fig. 5.
Example 6
1) 1kg of expanded graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the reactor to 20MPa, raising the temperature of the reaction kettle to 100 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 1000W, and the holding time is 2 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 20kg of N-methyl pyrrolidone and 0.1kg of polyvinyl alcohol to obtain a dispersion liquid, and placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 150MPa, and the homogenization treatment is repeatedly carried out for 4 times, and the treatment time is 25min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 1000W, the ultrasonic time is 2h, and drying after ultrasonic treatment to obtain graphene powder. The average number of layers was about 7 by atomic force microscopy.
Example 7
1) 1kg of natural graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to 30MPa, raising the temperature of the reaction kettle to 100 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 2000W, and the holding time is 1 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 40kg of deionized water and 0.05kg of polyvinylpyrrolidone to obtain a dispersion liquid, placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 180MPa, and repeatedly carrying out homogenization treatment for 5 times, and the treatment time is 40min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 1800W, the ultrasonic time is 1.5h, and freeze-drying after ultrasonic treatment to obtain graphene powder. The average number of layers was about 6 by atomic force microscopy.
Example 8
1) 1kg of expanded graphite is added into a high-temperature high-pressure reaction kettle connected with an ultrasonic machine, wherein an ultrasonic probe extends into the reaction kettle. Introducing carbon dioxide, adjusting the pressure in the kettle to 10MPa, raising the temperature of the reaction kettle to 150 ℃, and opening an ultrasonic machine, wherein the ultrasonic power is 1800W, and the holding time is 1 h. And then opening the pressure release valve, and collecting the materials while instantly releasing the pressure.
2) Fully mixing the material obtained in the step 1), 30kg of ethanol and 0.2kg of sodium lignosulfonate to obtain a dispersion liquid, and placing the dispersion liquid into a high-pressure homogenizer for homogenization treatment, wherein the pressure of the high-pressure homogenizer is 200MPa, and the homogenization treatment is repeatedly carried out for 3 times, and the treatment time is 35min each time;
3) and (3) placing the dispersion liquid obtained after homogenizing in the step 2) into an ultrasonic machine for secondary ultrasonic treatment, wherein the ultrasonic power is 2000W, the ultrasonic time is 1h, and drying after ultrasonic treatment to obtain graphene powder. The average number of layers was about 7 by atomic force microscopy.
It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.
Claims (10)
1. A method for preparing graphene by ultrasonic-assisted supercritical liquid phase exfoliation is characterized by comprising the following steps: taking graphite as a raw material, and carrying out carbon dioxide supercritical treatment and ultrasonic treatment on the graphite to obtain the graphene.
2. The method according to claim 1, further comprising adding a first solvent and a first dispersing agent to the graphite, and mixing them thoroughly to obtain a first dispersion as the raw material; the first solvent is selected from one or more of water, N-methyl pyrrolidone and ethanol, the first dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, lecithin, polyvinylpyrrolidone, polyvinyl alcohol, sodium lignin sulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid and polysorbate, the mass ratio of the graphite to the first solvent is 1: 10-200, and the mass ratio of the graphite to the first dispersing agent is 200-5: 1.
3. The method of claim 1, comprising:
placing the raw materials in a reaction kettle connected with ultrasonic equipment;
introducing carbon dioxide into the reaction kettle, adjusting the pressure of the reaction kettle to 8 MPa-100 MPa, adjusting the temperature to 35-500 ℃, setting the ultrasonic power to 500W-3000W, and keeping for 0.1-10 h for reaction.
4. The method of claim 3, further comprising: and adding a second solvent and a second dispersing agent into the reacted product, fully mixing to obtain a second dispersion solution, homogenizing the second dispersion solution under the pressure of 100-300 MPa, and drying to obtain the graphene.
5. The method of claim 4, wherein the second solvent is selected from one or more of water, N-methyl pyrrolidone, and ethanol, and the second dispersing agent is selected from one or more of sodium fatty acid, sodium amino acid, sodium ketosulfonamide, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, lecithin, polyvinyl pyrrolidone, polyvinyl alcohol, sodium lignosulfonate, alkyl glucoside, fatty glyceride, sorbitan fatty acid, and polysorbate; the mass ratio of the graphite to the second solvent is 1: 10-200, and the mass ratio of the graphite to the second dispersing agent is 200-5: 1.
6. The method according to claim 4, wherein the homogenization treatment is repeated 3 to 6 times, and the time for each homogenization treatment is 5 to 50 min.
7. The method according to claim 4, further comprising performing a secondary ultrasonic treatment after the homogenizing treatment, and drying to obtain the graphene; wherein the power of the secondary ultrasonic treatment is 500-3000W, and the time is 1-5 h.
8. The method of claim 1, wherein the graphite is one or more of natural graphite, artificial graphite, and expanded graphite.
9. The method of claim 1, wherein the graphite is in a powder form having a particle size of 1 μm to 100 μm.
10. The method according to claim 1, wherein the number of graphene layers is 5 to 10.
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| CN112607728A (en) * | 2020-11-20 | 2021-04-06 | 中国科学院深圳先进技术研究院 | Automatic device for preparing graphene composite material by ultrasonic-assisted supercritical fluid |
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