CN112960668A - Method for preparing graphene powder by water-phase enhanced stripping method - Google Patents
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 195
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 99
- 238000000034 method Methods 0.000 title claims abstract description 73
- 239000000843 powder Substances 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 claims abstract description 20
- 229910002804 graphite Inorganic materials 0.000 claims description 86
- 239000010439 graphite Substances 0.000 claims description 86
- 238000003756 stirring Methods 0.000 claims description 21
- 239000007864 aqueous solution Substances 0.000 claims description 20
- 239000006185 dispersion Substances 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 15
- 239000002002 slurry Substances 0.000 claims description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- 238000005406 washing Methods 0.000 claims description 13
- 239000005457 ice water Substances 0.000 claims description 12
- 238000010008 shearing Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 9
- 238000004108 freeze drying Methods 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 239000010410 layer Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 239000011229 interlayer Substances 0.000 claims description 7
- 239000007800 oxidant agent Substances 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 6
- 239000012298 atmosphere Substances 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 230000007935 neutral effect Effects 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 238000001291 vacuum drying Methods 0.000 claims description 5
- 238000005411 Van der Waals force Methods 0.000 claims description 4
- 125000000524 functional group Chemical group 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims description 2
- 229910052744 lithium Inorganic materials 0.000 claims description 2
- 229910052700 potassium Inorganic materials 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- 230000002195 synergetic effect Effects 0.000 claims description 2
- 238000004299 exfoliation Methods 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 9
- 239000003638 chemical reducing agent Substances 0.000 abstract description 8
- 238000009776 industrial production Methods 0.000 abstract description 7
- 231100000331 toxic Toxicity 0.000 abstract description 7
- 230000002588 toxic effect Effects 0.000 abstract description 7
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract description 3
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 238000011946 reduction process Methods 0.000 abstract description 2
- 238000006722 reduction reaction Methods 0.000 abstract description 2
- 230000033116 oxidation-reduction process Effects 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- 239000012065 filter cake Substances 0.000 description 14
- 238000000967 suction filtration Methods 0.000 description 13
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000009830 intercalation Methods 0.000 description 4
- 230000002687 intercalation Effects 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 239000012286 potassium permanganate Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 229910017717 NH4X Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000000138 intercalating agent Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/184—Preparation
- C01B32/19—Preparation by exfoliation
Abstract
The invention discloses a method for preparing graphene powder by a water-phase enhanced stripping method. At present, graphene prepared by an oxidation-reduction method is a main mode of industrial production, however, the production period is long, the prepared graphene is easy to agglomerate and difficult to disperse, and meanwhile, toxic and harmful reducing agents such as hydrazine hydrate and the like are needed in the chemical reduction process, and the lattice structure of the graphene can be damaged in the reduction process. Various preparation defects restrict the popularization of the industrial production and application of the graphene. In order to solve the technical problems, the invention provides the graphene powder which is environment-friendly, beneficial to industrial production and not easy to agglomerate. Compared with the preparation process of the reduced graphene oxide, the experimental process is safe and reliable, the process period is greatly shortened, and the time cost is saved.
Description
Technical Field
The invention relates to the field of carbon nano-material preparation, in particular to a method for preparing graphene powder by a water-phase enhanced stripping method.
Background
The current preparation method of graphene mainly comprises a mechanical stripping method, a redox method, a chemical vapor deposition method and the like, wherein the redox method for preparing graphene is the main mode for realizing industrial production at present. According to the method, chemical reagents such as concentrated sulfuric acid and concentrated nitric acid are used as an intercalation agent and oxidizing agents such as potassium permanganate to perform intercalation oxidation on natural graphite, the distance between graphite layers is increased, oxygen-containing functional groups are inserted between the layers to prepare graphite oxide, then the graphite oxide is peeled by methods such as mechanical peeling to prepare graphene oxide, and then the graphene oxide is reduced to graphene by using a strong reducing agent. The method for preparing the graphene powder is simple, but the production period is long, the prepared graphene is easy to agglomerate and difficult to disperse, and meanwhile, toxic and harmful reducing agents such as hydrazine hydrate and the like are needed in the chemical reduction process, so that the lattice structure of the graphene can be damaged in the reduction process. Various preparation defects restrict the popularization of the industrial production and application of the graphene.
In order to improve the preparation process, in patent CN 106882796A, a three-dimensional graphene structure is prepared by oxidizing a graphite intercalation, and graphene is obtained by a mechanical stripping method, so that a toxic and harmful strong reducing agent is not introduced, and the experimental process is environment-friendly. The obtained graphene has a perfect structure and good dispersibility in an organic solvent or a surfactant. However, the number of graphene layers prepared by a mechanical stripping method is not uniformly distributed, and the problem of graphene agglomeration is not improved.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide the graphene powder which is environment-friendly, beneficial to industrial production and not easy to agglomerate.
One of the purposes of the invention is to provide a preparation method of a water phase enhanced stripping method, which has the following principle: under the action of concentrated sulfuric acid and oxidant, the interlayer of the scale graphite is opened. And then decomposing the interlayer compound at high temperature to release gas to push away the graphite interlayer space, so that the graphite is expanded at high power to obtain the vermicular expanded graphite. The graphite is partially oxidized under the action of an oxidant, a certain amount of oxygen-containing functional groups are generated on the surface, and the expanded graphite can be uniformly dispersed in an alkaline aqueous solution and has a certain viscosity coefficient when the concentration is higher. The tangential force, which is exactly opposite to the shear force, is caused by the viscosity under the action of high-speed shear. While in alkaline aqueous solution, OH-Attached to oxygen-containing graphite watchAnd the electrostatic repulsion between the layers is increased, the van der Waals force is weakened, and the expanded graphite is completely peeled into graphene under the synergistic effect.
The second purpose of the invention is that the preparation of the expanded graphite by the method only takes several hours, so that compared with the preparation process of reducing graphene oxide, the process period is greatly shortened, and the time cost is saved.
The third purpose of the invention is to utilize concentrated sulfuric acid and hydrogen peroxide as an intercalating agent and an oxidant, and to avoid potassium permanganate or fuming nitric acid and other strong oxidants which produce toxic, harmful and explosive substances, so that the experimental process is safe and reliable.
The fourth purpose of the invention is that no toxic strong reducing agent is used, and the preparation process is environment-friendly.
The fifth purpose of the invention is to introduce OH-And the van der waals force between the sheets is weakened, and the graphene is not easy to agglomerate.
Adopts the technical proposal
The invention relates to a method for preparing graphene powder by a water-phase enhanced stripping method, which comprises the following specific steps:
1. preparation of expandable graphite
Under the ice water condition, the volume ratio of (2-4): 1, slowly adding concentrated sulfuric acid into hydrogen peroxide (30%), stirring for 30min, heating to 30-40 ℃, adding crystalline flake graphite, stirring for 1-6 h, washing until the dispersion is neutral, and drying in vacuum to obtain the expandable graphite.
2. Preparation of expanded graphite
And rapidly expanding the expandable graphite for 8-30 s at 600-1050 ℃ to obtain the vermicular expanded graphite.
3. Preparation of graphene slurry
Mixing alkaline substance A (OH) according to the proportion of 1-3 mol/LxAdding into pure water, and stirring to obtain alkaline aqueous solution. And (3) uniformly dispersing the expanded graphite obtained in the step (2) into an alkaline aqueous solution to obtain a dispersion liquid with a certain viscosity, then placing the dispersion liquid into a high-speed shearing machine for complete stripping, and finally completely stripping the expanded graphite to obtain the graphene slurry.
4. Preparation of graphene powder
And washing the graphene slurry with water until the pH value is 7-9, and freeze-drying to obtain graphene powder.
The invention discloses a method for preparing graphene powder by using a water-phase enhanced stripping method, wherein the particle size range of crystalline flake graphite is 2-500 mu m.
The invention discloses a method for preparing graphene powder by using a water-phase enhanced stripping method, wherein the mass ratio of graphite to concentrated sulfuric acid is 1: (10-40).
The method for preparing the graphene powder by the water-phase enhanced stripping method comprises the following steps of drying at 30-70 ℃ for 24-48 hours in vacuum.
The method for preparing the graphene powder by the water-phase enhanced stripping method disclosed by the invention is characterized in that the expansion atmosphere of the expandable graphite can be an inert atmosphere, an air atmosphere or vacuum.
The method for preparing the graphene powder by the water-phase enhanced stripping method is characterized in that the expandable graphite is preferably expanded at 700-1000 ℃.
The invention relates to a method for preparing graphene powder by using a water-phase enhanced stripping method, wherein A comprises Li, K, Na and NH4X is more than or equal to 1 and less than or equal to 3.
The invention relates to a method for preparing graphene powder by using a water-phase enhanced stripping method, wherein the mass ratio of expanded graphite to an alkaline aqueous solution is 1: (10-50).
The method for preparing the graphene powder by the water phase enhanced stripping method is characterized in that the shearing rate is 10000-40000 rpm, and the time is 30-360 min.
The method for preparing the graphene powder by the water-phase enhanced stripping method disclosed by the invention is characterized in that the freeze drying time is 24-96 hours.
Advantageous effects
1) The method has the advantages of simple process and short preparation period, and is suitable for batch industrial production.
2) The invention does not introduce toxic, harmful and explosive substances such as nitric acid, potassium permanganate and the like and toxic strong reducing agents such as hydrazine hydrate and the like in the preparation process, and the experimental process is environment-friendly.
3) The water-phase enhanced stripping method utilizes the viscosity characteristic of the expanded graphite to increase the stripping effect of the graphite sheet under high-speed shearing, does not damage the graphite lattice structure, and obtains the graphene with few defects and complete lattice structure.
4) The invention utilizes OH-Can adhere to the graphite oxide sheet layer, increases the electrostatic repulsion between the sheet layers due to the increase of negative charges, weakens the van der Waals force, reduces the stripping difficulty, and has OH in the dispersion liquid-And agglomeration of graphene sheets is prevented.
Drawings
Fig. 1 is a schematic diagram of the present invention.
FIG. 2 is an optical photograph of 1g of flake graphite and vermicular expanded graphite in example 1.
Fig. 3 is an electron micrograph of graphene prepared in example 1 magnified 50000 times.
Fig. 4 is a test result of the graphene XPS C1s prepared in example 1.
Detailed Description
The reference ratio is 1:
(1) adding 500mL of concentrated sulfuric acid into 50mL of concentrated nitric acid slowly under the condition of ice water, uniformly mixing, heating to room temperature, adding 10g of crystalline flake graphite into a reaction solution, stirring for 24h, and performing suction filtration to obtain a graphite interlayer filter cake.
(2) And (2) slowly adding 100mL of concentrated sulfuric acid into 10mL of hydrogen peroxide (30%) under the condition of ice-water bath, uniformly stirring, heating the mixed solution to 40 ℃, adding the filter cake obtained in the step (1) into the mixed solution, stirring at room temperature for 15min, standing for expansion for 48h, filtering, and washing with water to obtain the three-dimensional graphene structure.
(3) And (3) placing 1g of wet three-dimensional graphite structure body in 100mL of N-methyl pyrrolidone, uniformly dispersing, and shearing for 60min at a speed of 20000rpm by using a high-speed shearing machine to obtain single-layer and few-layer graphene.
Example 1:
(1) slowly adding 700mL of concentrated sulfuric acid into 300mL of hydrogen peroxide (30%) under the condition of ice-water bath, stirring for 30min, heating to 35 ℃, adding 35g of 270-micron scale graphite, stirring for 2h, carrying out suction filtration to remove acid liquor, slowly adding a filter cake into ice water, uniformly stirring, continuing suction filtration, washing for 7 times, enabling the pH value of a graphite dispersion to be close to neutral, carrying out suction filtration to obtain a graphite filter cake, and drying the filter cake in a vacuum drying oven at 60 ℃ for 24h to obtain the expandable graphite.
(2) The expandable graphite is rapidly expanded in batches in air at 900 ℃ for 10s to obtain the vermicular expanded graphite. (3) 28g of NaOH solid was weighed and added to 700mL of pure water, and the mixture was sufficiently stirred to obtain a 1mol/L NaOH aqueous solution. Then 35g of vermicular expanded graphite is added into 700mL of NaOH aqueous solution with the concentration of 1mol/L and stirred for 30min to obtain viscous dispersion liquid, and then the dispersion liquid is placed into a high-speed shearing machine to be sheared for 120min at the speed of 20000rpm to obtain graphene slurry. And (3) centrifugally washing the graphene slurry for 10 times, wherein the pH value of the graphene aqueous solution is about 8, and centrifuging to obtain the graphene pressed powder.
(4) And (4) freeze-drying the graphene pressed powder for 2 days to obtain graphene powder.
An optical photograph of 1g of flake graphite and vermicular expanded graphite of example 1 is shown in FIG. 2, wherein the flake graphite has a diameter of 270 μm and a thickness of about 40 μm, and the expanded graphite expands nearly 300 times in volume and the stacking thickness of the sheets is greatly reduced. Fig. 3 shows a scanning electron microscope image of the graphene powder prepared in example 1, and a light-yarn-shaped semitransparent structure of graphene with a complete structure can be clearly seen under a scanning electron microscope, which indicates that the graphene prepared in example 1 is single-layer graphene. The XPS 1Cs test result of the graphene powder is shown in FIG. 4, which shows that the carbon content is about 95% and the carbon is hybridized (sp)3) The content is less, and the structural integrity of the graphene is further confirmed.
Example 2:
(1) slowly adding 700mL of concentrated sulfuric acid into 300mL of hydrogen peroxide (30%) under the condition of ice-water bath, stirring for 30min, heating to 35 ℃, adding 35g of 270-micron scale graphite, stirring for 6h, carrying out suction filtration to remove acid liquor, slowly adding a filter cake into ice water, stirring uniformly, continuing suction filtration, washing for 7 times to ensure that the pH value of a graphite dispersion liquid is close to neutral, carrying out suction filtration to obtain a graphite filter cake, and drying the filter cake in a vacuum drying oven at 30 ℃ for 48h to obtain the expandable graphite.
(2) The expandable graphite is rapidly expanded in batches in air at 900 ℃ for 10s to obtain the vermicular expanded graphite. (3) 56g of NaOH solid was weighed and added to 700mL of pure water, and the mixture was sufficiently stirred to obtain a 2mol/L NaOH aqueous solution. Then 35g of vermicular expanded graphite is added into 700mL of 1mol/L NaOH aqueous solution and stirred for 30min to obtain viscous dispersion liquid, and then the dispersion liquid is placed into a high-speed shearing machine to be sheared for 90min at the speed of 20000rpm, so that graphene slurry is obtained. And (3) centrifugally washing the graphene slurry for 10 times, wherein the pH value of the graphene aqueous solution is about 8, and centrifuging to obtain the graphene pressed powder.
(4) And (4) freeze-drying the graphene pressed powder for 2 days to obtain graphene powder.
The graphene prepared in example 2 was found to have a relatively low carbon content (87%) by XPS elemental analysis, and its increased oxygen-containing functional group content was caused by a longer intercalation oxidation time.
Example 3:
(1) adding 400mL of concentrated sulfuric acid slowly into 100mL of hydrogen peroxide (30%) under the condition of ice-water bath, stirring for 30min, heating to 30 ℃, adding 20g of 10-micron scale graphite, stirring for 2h, carrying out suction filtration to remove acid liquor, slowly adding a filter cake into ice water, stirring uniformly, continuing suction filtration, washing with water until the pH value of a graphite dispersion liquid is close to neutral, carrying out suction filtration to obtain a graphite filter cake, and drying the filter cake in a vacuum drying oven at 30 ℃ for 48h to obtain the expandable graphite.
(2) And rapidly expanding the expandable graphite in batches in the air at 800 ℃ for 10s to obtain the expanded graphite.
(3) 11.2g of KOH solid was weighed and added to 200mL of pure water and sufficiently stirred to obtain a 1mol/L KOH aqueous solution. Then 20g of expanded graphite is added into 200mL of 1mol/L KOH aqueous solution and stirred for 40min to obtain viscous dispersion liquid, and then the dispersion liquid is placed in a high-speed shearing machine to be sheared for 60min at the speed of 20000rpm, so that graphene slurry is obtained. And (4) centrifugally washing the graphene slurry until the pH value of the graphene aqueous solution is about 8, and continuously centrifuging to obtain the graphene pressed powder.
(4) And (4) freeze-drying the graphene pressed powder for 2 days to obtain graphene powder.
Example 4:
(1) adding 400mL of concentrated sulfuric acid slowly into 100mL of hydrogen peroxide (30%) under the condition of ice-water bath, stirring for 30min, heating to 30 ℃, adding 20g of flake graphite with the particle size of 2.6 microns, stirring for 2h, carrying out suction filtration to remove acid liquor, slowly adding a filter cake into ice water, stirring uniformly, continuing suction filtration, washing with water until the pH value of a graphite dispersion liquid is close to neutral, carrying out suction filtration to obtain a graphite filter cake, and drying the filter cake in a vacuum drying oven at 60 ℃ for 24h to obtain the expandable graphite.
(2) And rapidly expanding the expandable graphite in batches in the air at 800 ℃ for 10s to obtain the expanded graphite.
(3) 75mL of ammonia (25%) was measured and diluted to 1L to obtain a 1mol/L ammonia solution. Then 20g of expanded graphite is added into 200mL of 1mol/L ammonia water solution and stirred for 40min to obtain viscous dispersion liquid, and then the dispersion liquid is placed into a high-speed shearing machine to be sheared for 300min at the speed of 30000rpm to obtain graphene slurry. And (4) centrifugally washing the graphene slurry until the pH value of the graphene aqueous solution is about 7, and continuously centrifuging to obtain the graphene pressed powder.
(4) And (4) freeze-drying the graphene pressed powder for 3 days to obtain graphene powder.
Claims (16)
1. A method for preparing graphene by a water-phase enhanced stripping method is characterized in that under the action of concentrated sulfuric acid and an oxidant, the interlayer of crystalline flake graphite is opened.
2. A method for preparing graphene by a water-phase enhanced stripping method is characterized in that a compound among layers is decomposed at a high temperature to release gas to push away graphite interlayer spacing, so that graphite is subjected to high-power expansion.
3. A method for preparing graphene by a water-phase enhanced stripping method is characterized in that graphite is partially oxidized under the action of an oxidant, a certain amount of oxygen-containing functional groups are generated on the surface, and expanded graphite can be uniformly dispersed in an alkaline aqueous solution and has a certain viscosity coefficient when the concentration is higher.
4. A method for preparing graphene by a water-phase enhanced stripping method is characterized in that a tangential force which is completely opposite to a shearing force is caused by viscosity under the action of high-speed shearing.
5. A method for preparing graphene by a water-phase enhanced stripping method is characterized in that OH & lt- & gt is attached to the surface of oxygen-containing graphite in an alkaline aqueous solution, interlayer electrostatic repulsion is increased, van der Waals force is weakened, and expanded graphite is completely stripped into graphene under a synergistic effect.
6. The method for preparing graphene powder according to claims 1-5, which comprises the following steps:
(1) preparation of expandable graphite
Under the ice water condition, the volume ratio of (2-4): 1, slowly adding concentrated sulfuric acid into hydrogen peroxide (30%), stirring for 30min, heating to 30-40 ℃, adding crystalline flake graphite, stirring for 1-6 h, washing until the dispersion is neutral, and drying in vacuum to obtain expandable graphite
(2) Preparation of expanded graphite
Rapidly expanding the expandable graphite for 8-30 s at 600-1050 ℃ to obtain vermicular expanded graphite
(3) Preparation of graphene slurry
Adding an alkaline substance A (OH) x into pure water according to the proportion of 1-3 mol/L, and fully stirring to obtain an alkaline aqueous solution
(4) And (3) uniformly dispersing the expanded graphite obtained in the step (2) into an alkaline aqueous solution to obtain a dispersion liquid with a certain viscosity, then placing the dispersion liquid into a high-speed shearing machine for complete stripping, and finally completely stripping the expanded graphite to obtain the graphene slurry.
7. Preparation of graphene powder
And washing the graphene slurry with water until the pH value is 7-9, and freeze-drying to obtain graphene powder.
8. The method for preparing graphene powder according to claims 1-5, wherein the particle size of the flake graphite is 2-500 μm.
9. The method for preparing graphene powder according to claims 1-5, wherein the mass ratio of graphite to concentrated sulfuric acid is 1: (10-40).
10. The method for preparing graphene powder according to the water-phase enhanced exfoliation method of claims 1-5, wherein the first step is vacuum drying at 30-70 ℃ for 24-48 h.
11. The method for preparing graphene powder according to claims 1-5, wherein the atmosphere in which the expandable graphite expands may be an inert atmosphere, an air atmosphere or a vacuum.
12. The method for preparing graphene powder according to claims 1 to 5, wherein the expandable graphite is preferably expanded at 700 to 1000 ℃.
13. The method for preparing graphene powder according to claims 1-5, wherein A comprises at least one of Li, K, Na and NH4, and x is 1-3.
14. The method for preparing graphene powder according to claims 1 to 5, wherein the mass ratio of the expanded graphite to the alkaline aqueous solution is 1: (10-50).
15. The method for preparing graphene powder according to claims 1-5, wherein the shear rate is 10000-40000 rpm, and the time is 30-360 min.
16. The method for preparing graphene powder according to the water-phase enhanced exfoliation method of claims 1-5, wherein the freeze-drying time is 24-96 hours.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115231559A (en) * | 2022-08-24 | 2022-10-25 | 常熟世名化工科技有限公司 | Graphene, preparation method thereof and graphene water-based dispersion |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115231559A (en) * | 2022-08-24 | 2022-10-25 | 常熟世名化工科技有限公司 | Graphene, preparation method thereof and graphene water-based dispersion |
| CN115231559B (en) * | 2022-08-24 | 2023-11-03 | 常熟世名化工科技有限公司 | Graphene, preparation method thereof and graphene water-based dispersion |
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