CN110550620B - Graphene and preparation method thereof - Google Patents

Graphene and preparation method thereof Download PDF

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CN110550620B
CN110550620B CN201810538740.9A CN201810538740A CN110550620B CN 110550620 B CN110550620 B CN 110550620B CN 201810538740 A CN201810538740 A CN 201810538740A CN 110550620 B CN110550620 B CN 110550620B
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graphene
graphite
hours
oxidant
reaction
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CN110550620A (en
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徐伟箭
欧恩才
史春风
张晓燕
鲍琳
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • 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
    • 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
    • C01B32/194—After-treatment
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00—Structure or properties of graphene
    • C01B2204/20—Graphene characterized by its properties
    • C01B2204/28—Solid content in solvents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/01—Crystal-structural characteristics depicted by a TEM-image
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data

Abstract

The invention relates to the field of functional materials, and discloses graphene and a preparation method thereof, wherein graphene aqueous dispersion with the content of 0.02-2 weight per thousand is prepared and stood, the absorbances of upper, middle and bottom graphene aqueous dispersions with the same volume and the same solvent solutions with the same concentration are respectively measured at the same temperature, after standing for 2 hours, the relative deviation of the absorbances of the upper, middle and bottom graphene aqueous dispersions is not higher than 5%, preferably less than or equal to 1%, and after standing for 24 hours, the relative deviation of the absorbances of the upper, middle and bottom graphene aqueous dispersions is not higher than 10%, preferably less than or equal to 3%. The graphene provided by the invention is different from the traditional graphene, can be fully and stably dispersed in water, and has good dispersibility in water, so that the problem of the hydrophobicity of the traditional graphene is solved, the problem of poor compatibility with other materials due to the inherent hydrophobicity of a carbon material is solved, and the application range of the graphene is expanded.

Description

Graphene and preparation method thereof
Technical Field
The invention relates to graphene and a preparation method thereof, in particular to graphene with good water dispersibility and a preparation method thereof.
Background
The unique two-dimensional structure of graphene makes it have a structure that can be as high as 2600cm2Specific surface area per gram, high Young modulus and carrier mobility, excellent conductivity, thermal conductivity, mechanical property, light transmittance and the like. Among the known materials, graphene is the substance of highest known strength by humans, and is more than 100 times that of steel. Graphene is also an additive to nanocomposites. With the continuous and deep research on graphene, the application range of graphene is continuously expanded, so that the preparation of graphene becomes an important research topic.
However, due to the inherent hydrophobicity of the carbon material, graphene produced by the prior art is difficult to be fully dispersed in water, the dispersion stability in water is poor, and "water-soluble" graphene capable of being well dispersed in water is difficult to obtain, so how to solve the problem of the dispersibility of graphene in water is a difficult point and a key for obtaining the "water-soluble" graphene. The solution is that graphene is modified usually, but the graphene has stable chemical properties, and a large amount of strong acid and strong oxidant such as concentrated sulfuric acid, potassium permanganate and the like are required to be used for oxidizing the graphene (such as oxidized graphene) in order to perform modification, and then the oxidized graphene is subjected to graft modification through chemical reaction. However, oxidation of graphene by strong acids and strong oxidants not only destroys the structure of graphene, but also degrades its performance. In addition, due to poor water dispersibility of graphene, graphene cannot be uniformly dispersed in other materials, such as paint, plastic, resin, rubber, etc., which greatly limits the application of graphene.
Therefore, in view of the problems of poor graphene dispersibility and defects in the quality of the obtained graphene in the methods for preparing graphene in the prior art, the development of a novel method for preparing graphene is still under further study, and the present invention is therefore particularly proposed.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide graphene with good water dispersibility and a preparation method thereof.
In order to achieve the above object, in one aspect, the present invention provides graphene, wherein a graphene aqueous dispersion with a content of 0.02 to 2 wt% is prepared and left to stand, and the absorbances of the same solvent solutions with the same concentrations of the upper, middle and bottom graphene aqueous dispersions are respectively measured at the same temperature, after standing for 2 hours, the relative deviation of the absorbances of the solutions of the upper, middle and bottom graphene aqueous dispersions is not higher than 5%, preferably less than or equal to 1%, and after standing for 24 hours, the relative deviation of the absorbances of the solutions of the upper, middle and bottom graphene aqueous dispersions is not higher than 10%, preferably less than or equal to 3%.
Preferably, the assay method comprises: respectively measuring the absorbances of the same solvent dissolving solutions with the same concentration of the upper graphene water dispersion liquid, the middle graphene water dispersion liquid and the bottom graphene water dispersion liquid with the same volume, respectively recording the absorbances as S1, S2, S3, S1 or S2 or S3 and the average value of S1, S2 and S3 in the measurement, recording the absolute values of the differences as RS1, RS2 and RS3, and recording the percentages of the ratios of RS1, RS2 and RS3 to the average value of S1, S2 and S3 in the measurement as DS1, DS2 and DS 3; after standing for 2 hours, the relative deviations DS1, DS2 and DS3 are respectively in the ranges of 0.1-2, 0.1-2 and 0.1-5, preferably 0.1-0.5, 0.1-0.5 and 0.1-0.8; after standing for 24h, the relative deviations DS1, DS2 and DS3 are respectively in the ranges of 0.1-5, 0.1-5 and 0.1-10, preferably 0.1-1.5, 0.1-2 and 0.1-3.
The second aspect of the present invention provides a preparation method of graphene, wherein the preparation method comprises the following steps:
(1) the graphite is in contact reaction with an intercalation agent to obtain graphite with increased interlayer spacing, wherein the intercalation agent is selected from at least one of hydrazine hydrate, carbon disulfide, elemental phosphorus and elemental sulfur;
(2) contacting the graphite with increased interlayer spacing obtained in the step (1) with an oxidant, wherein the oxidant is selected from at least one of oxygen-containing gas, ozone, chlorine dioxide, hypochlorous acid, nitric acid, hydrogen peroxide, benzoyl peroxide and dicumyl peroxide;
(3) and (3) carrying out ultrasonic stripping treatment on the product obtained in the step (2).
Preferably, in step (1), the intercalation agent is selected from one or more of elemental sulfur, elemental phosphorus and hydrazine hydrate, and in step (2), the oxidizing agent is selected from one or more of hydrogen peroxide, ozone and benzoyl peroxide.
In a third aspect, the present invention provides a graphene prepared by the method of the present invention.
Compared with the prior art, the invention has the beneficial effects that:
1) the graphene provided by the invention is different from the traditional graphene, can be fully and stably dispersed in water, and has good dispersibility in water, so that the problem of the hydrophobicity of the traditional graphene is changed, the problem of poor compatibility with other materials due to the inherent hydrophobicity of a carbon material is solved to a certain extent, and the application range of the graphene is expanded.
2) The preparation method of the graphene provided by the invention can be carried out on the existing industrial equipment, and the preparation process has the advantages of small using amount of the used oxidant, simple, quick, environment-friendly, easy operation and the like, and is easy to industrialize.
Drawings
Fig. 1 is a raman spectrum of graphene prepared according to the present invention, wherein (a) in fig. 1 corresponds to example 1, (b) in fig. 1 corresponds to example 4, and (c) in fig. 1 corresponds to example 5;
fig. 2 is a transmission electron microscope image of graphene prepared in example 1 of the present invention;
fig. 3 is a transmission electron microscope image of graphene prepared in example 4 of the present invention;
fig. 4 is a transmission electron microscope image of graphene prepared in example 5 of the present invention.
Detailed Description
The endpoints of the ranges and any values disclosed herein 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 give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The graphene provided by the invention has good and stable dispersion performance in water. In the invention, the stability of the graphene aqueous dispersion is defined by preparing the graphene aqueous dispersion and standing, and measuring the absolute deviation and the relative deviation of the absorbance of the graphene aqueous dispersion in a solvent solution at different positions sampled after standing for different times under the same conditions.
Specifically, according to the present invention, a graphene aqueous dispersion having a content of 0.02 to 2% by weight is prepared and left to stand, and the absorbances of the same solvent solutions of the same concentration of the same volume of upper, middle and bottom graphene aqueous dispersions are measured at the same temperature and are respectively recorded as S1, S2, S3, S1 or S2 or S3, as absolute values of the difference from the average value of S1, S2, S3 in this measurement as RS1, RS2, RS3, that is, the absolute deviation values (absolute deviation values ═ individual measurement values — arithmetic average values of multiple measurements) are recorded, and the percentages of the ratios of RS1, RS2, RS3 to the average values of S1, S2, S3 in this measurement are recorded as DS1, DS2, DS 3; that is, the relative deviation value (the relative deviation value is the percentage of the absolute deviation of a certain measurement to the average value and is used for measuring the deviation degree of a single measurement result from the average value) is recorded, and after standing for 2 hours, the measurement is carried out for multiple times, and the ranges of DS1, DS2 and DS3 are 0.1-2, 0.1-5, preferably 0.1-0.5, 0.1-0.5 and 0.1-0.8; standing for 24 hr, and measuring for several times, wherein DS1, DS2, and DS3 are 0.1-5, and 0.1-10, preferably 0.1-1.5, 0.1-2, and 0.1-3, respectively.
According to the invention, an aqueous graphene dispersion with a content of 0.02 to 2 wt.% is prepared and left to stand, preferably an aqueous graphene dispersion with a content of 0.05 to 1 wt.% is prepared and left to stand, the standing time can be 0.1-6h, after the standing, samples sampled from different positions of the upper, middle and lower parts of the graphene aqueous dispersion are respectively dissolved in the same solvent to form dissolved solutions, the relative deviation of the absorbance of the dissolved solutions measured after the standing is 2h is not higher than 5%, preferably not higher than 1%, after the standing is 24h, the samples sampled from different positions of the graphene aqueous dispersion are respectively dissolved in the same polar solvent, and the relative deviation of the absorbance of the dissolved solutions measured is not higher than 10%, preferably not higher than 1%, so that the graphene provided by the invention has good and stable dispersibility in water. The number of measurements per sampling site is usually 3 to 20, preferably 5 to 10, and the average value is used as the measurement result by default.
More specifically, as can be seen from the raman spectrum of the graphene prepared in example 4 (fig. 1 (b)), it is located at 1350cm-1、1580cm-1And 2700cm-1A characteristic peak D, a G peak, and a 2D peak of graphene appear nearby. Wherein, 1350cm-1The D peak is a defect peak at 1580cm-1The G peak in the vicinity is a characteristic peak of a carbon sp2 hybrid structure, ID/IGReflects the irregularity degree of the graphene lamellar structure, is an important index for judging the order of the graphene, and the D peak of the graph (b) in figure 1 is lower, which shows that the oxidation degree of the graphite is lower, ID/IG0.22, which shows that although oxygen has a certain oxidation effect on the intercalated graphite, the graphitization degree of the graphene is still relatively high, and the microstructure shows that the stripping degree of the graphene is not high, and the water solubility is not optimal. As can be seen from the raman spectrograms of the graphenes prepared in example 5 and example 1 (fig. 1 (c) and (a), respectively), the D peak intensities of (c) and (a) in fig. 1 are increased, indicating that the degree of oxidation of the graphenes by hydrogen peroxide and ozone is increased, and I in fig. 1 (c)D/IGIs 0.76, I of diagram (a) in FIG. 1D/IGThe value of 0.79 indicates that the prepared graphene has a reduced graphitization degree, an improved exfoliation degree and better water solubility.
According to the invention, the measurement temperature of the graphene dispersibility can be normal temperature to 100 ℃, and preferably, the measurement temperature of the graphene dispersibility is 20-60 ℃. Graphene exhibits good solubility in certain solvents, and thus, in a method for determining graphene dispersibility, the solvent may be selected from one or more of water, Dimethylsulfoxide (DMSO), N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), oleic acid, and naphthenic acid; the mass concentration of the solvent dissolving solution can be 0.1-20 per thousand, and preferably 0.2-10 per thousand.
According to the present invention, the preparation method of graphene comprises the following steps:
(1) the graphite is in contact reaction with an intercalation agent to obtain graphite with increased interlayer spacing, wherein the intercalation agent is selected from at least one of hydrazine hydrate, carbon disulfide, elemental phosphorus and elemental sulfur;
(2) contacting the graphite with increased interlayer spacing obtained in the step (1) with an oxidant, wherein the oxidant is selected from at least one of air, oxygen, ozone, chlorine dioxide, chlorine gas, hypochlorous acid, nitric acid, hydrogen peroxide, benzoyl peroxide and dicumyl peroxide;
(3) and (3) carrying out ultrasonic stripping treatment on the product obtained in the step (2).
The layered structure of graphite allows some voids to exist between layers, so that under certain conditions, atoms (or molecules) of some reactants (such as acid, alkali, halogen, etc.) can enter the interlayer space and form an interlayer compound with the carbon network. According to the preparation method of the graphene, the specific intercalation agent and the oxidant are combined for use, the specific intercalation agent is firstly utilized to prepare the graphite with the increased interlayer spacing, and then the oxidant is utilized to remove the intercalation agent to prepare the graphene. Specifically, the intercalation agent is selected from at least one of hydrazine hydrate, carbon disulfide, elemental phosphorus, and elemental sulfur; the oxidant is at least one selected from air, oxygen, ozone, chlorine dioxide, chlorine gas, hypochlorous acid, nitric acid, hydrogen peroxide, benzoyl peroxide and dicumyl peroxide.
According to the present invention, it is further preferred that the intercalating agent is selected from one or more of elemental sulfur, elemental phosphorus and hydrazine hydrate, and in step (2), the oxidizing agent is selected from one or more of hydrogen peroxide, ozone and benzoyl peroxide; more preferably, in step (1), the intercalation agent is elemental sulfur or a combination of elemental sulfur and elemental phosphorus and/or hydrazine hydrate, and when the intercalation agent selects elemental sulfur to be used in combination with other intercalation agents, the mass ratio of elemental sulfur to the total amount of elemental phosphorus and hydrazine hydrate is preferably 1: 0.1-1. In the step (2), the oxidant is preferably hydrogen peroxide and/or ozone in combination with the oxidant, so that the dispersion stability of the prepared graphene in water can be further improved, and the quality of the graphene is improved.
According to the invention, in the step (1), the mass ratio of the intercalation agent to the graphite can be 5-120:1, and in order to further prepare graphene with excellent quality, the mass ratio of the intercalation agent to the graphite is preferably 10-100: 1.
According to the invention, in the step (1), in the process of carrying out contact reaction between graphite and the intercalator to prepare the graphite with increased interlayer spacing, the contact mode of the intercalator and the graphite is not particularly limited, and when the intercalator is used in various combinations, the intercalator can be respectively mixed with the graphite (specifically, the intercalator can be added into the graphite and uniformly mixed), and the sequence of the contact of each intercalator and the graphite does not particularly influence the quality of the obtained graphite with increased interlayer spacing.
According to the invention, in step (1), the conditions of the contact reaction include: the reaction temperature may be 100-220 deg.C, preferably 120-200 deg.C, and the reaction time may be 2-15 hours, preferably 4-12 hours.
According to the present invention, preferably, the graphite having increased interlamellar spacings obtained after step (1) may have a multiple expansion of from 0.2 to 5 times relative to the graphite starting material (for graphite expansion measurement see GBT10698-1989 expandable graphite).
In the present invention, in step (1), the contact reaction of graphite and the intercalant may be carried out under stirring for the purpose of more complete reaction. The stirring rate may be suitably selected in accordance with the actual conditions, and for example, the stirring rate may be 20 to 2000 rpm, preferably 50 to 1000 rpm. Furthermore, preferably, in the step (1), after the graphite with increased interlayer spacing is obtained, a step of washing and drying the graphite with increased interlayer spacing may be further included, and the specific operation of washing and drying is well known to those skilled in the art, for example, the obtained mixture may be washed to neutrality with diluted hydrochloric acid and deionized water, and then subjected to suction filtration and drying. Specifically, after the reaction of graphite and the intercalating agent is finished, dilute hydrochloric acid may be used to perform multiple washing, and the amount of deionized water is gradually increased in the washing process, and the amount of dilute hydrochloric acid is decreased until the graphite is washed to be neutral, and the concentration of the dilute hydrochloric acid is not particularly limited and may be selected conventionally by those skilled in the art, and in the present invention, dilute hydrochloric acid having a concentration of 10 wt% is preferred. The method of filtration after washing is well known to those skilled in the art, and for example, suction filtration may be employed, and the suction filtration equipment and the suction filtration conditions are not particularly limited and may be selected conventionally by those skilled in the art. In the present invention, the drying method may be vacuum drying, freeze drying, spray drying, etc., and the drying equipment and drying conditions are not particularly limited and may be selected conventionally by those skilled in the art.
According to the present invention, the graphite may be selected from one or more of natural flake, graphite microcrystalline graphite, and synthetic graphite. The flake graphite is natural crystalline graphite which is shaped like fish scales and has a layered structure. The microcrystalline graphite is also called earthy graphite powder, amorphous graphite powder and black lead powder, and belongs to aphanitic graphite. The synthetic graphite is also called artificial graphite or artificial graphite, and in a broad sense, all graphite materials obtained by organic carbonization and graphitization high-temperature treatment can be called artificial graphite, such as carbon fiber, pyrolytic carbon, foam graphite and the like, while the artificial graphite in a narrow sense generally refers to a massive solid material prepared by taking a carbon raw material with low impurity content as an aggregate, coal pitch and the like as a binder and performing the procedures of batching, kneading, molding, carbonization, graphitization and the like, such as static pressure graphite and the like. The carbon content at the time of the lower content of the graphite impurity may be 99% by weight or more (i.e.,. gtoreq.99% by weight), preferably 99.99% by weight or more (i.e.,. gtoreq.99.99% by weight), and the average particle size of the graphite may be 30 to 500 mesh, preferably 50 to 350 mesh.
According to the present invention, in the step (2), the conditions for the contact reaction between the graphite with increased interlayer spacing obtained in the step (1) and the oxidizing agent are related to the selection of the oxidizing agent, but it is sufficient to ensure that the oxidation of the oxidizing agent is promoted and the intercalating agent in the graphite with increased interlayer spacing is decomposed under the corresponding reaction conditions.
Specifically, the oxidant may be air and/or oxygen, and the contact reaction conditions include: the reaction temperature may be 200-600 deg.C, preferably 300-500 deg.C, and the reaction time may be 0.1-8 hours, preferably 0.2-5 hours. Wherein, the dosage of the oxidant can be 2 to 10 times of the theoretical value of oxygen demand for decomposing the intercalating agent by the mass of the oxygen.
The oxidant may be selected from one or more of ozone, chlorine and chlorine dioxide, and the contact reaction conditions include: the reaction temperature may be 20 to 100 deg.C, preferably 30 to 80 deg.C, and the reaction time may be 0.1 to 8 hours, preferably 0.2 to 4 hours. The amount of oxidizing agent used may be from 1 to 5 times the theoretical amount of oxidizing agent used to decompose the intercalant.
The oxidant can be hypochlorous acid and/or nitric acid, and the contact reaction conditions comprise: the reaction temperature may be 30 to 80 ℃ and preferably 40 to 70 ℃ and the reaction time may be 1 to 8 hours and preferably 2 to 4 hours. The mass ratio of oxidant to graphite may be 0.5-10:1, preferably 1-8: 1.
The oxidant may be hydrogen peroxide, and the contact reaction conditions include: the reaction temperature may be 30 to 80 deg.C, preferably 40 to 60 deg.C, and the reaction time may be 0.5 to 8 hours, preferably 1 to 6 hours. The hydrogen peroxide is generally used in the form of an aqueous solution thereof, and the mass ratio of hydrogen peroxide to graphite may be 0.5 to 5:1, preferably 0.75 to 2: 1; wherein the concentration of the aqueous hydrogen peroxide solution is generally 10 to 70% by weight.
The oxidant can be benzoyl peroxide and/or dicumyl peroxide, and the contact reaction conditions comprise: the reaction temperature may be 100-150 deg.C, preferably 110-140 deg.C, and the reaction time may be 4-12 hours, preferably 5-10 hours. The mass ratio of oxidant to graphite may be 0.5-10:1, preferably 1-8: 1.
Preferably, when the oxidizing agents are used in a plurality of combinations, the amount of each oxidizing agent can be reduced to 1/3-1/2 in the amount of the oxidizing agent used alone.
In the present invention, in the step (2), in order to allow the reaction to be more sufficient, when the oxidizing agent is in a liquid phase, the graphite having an increased interlayer distance obtained in the step (1) may be contacted with the oxidizing agent while stirring. The stirring rate may be suitably selected in accordance with the actual operation, and for example, the stirring rate may be 50 to 1000 rpm.
According to the present invention, in order to obtain a better exfoliation effect of the prepared graphene particles, the method further comprises the step (3): and (3) carrying out ultrasonic stripping treatment on the product obtained in the step (2). The ultrasonic exfoliation treatment is usually performed in a solvent, and the type of the solvent is not particularly limited in the present invention, and may be any of various existing inert liquid substances capable of performing a dispersing action, such as various existing alcohol solvents, ester solvents, ether solvents, amide solvents, water, and the like, but in order to facilitate the solvent to enter between graphite layers to promote the exfoliation of graphene, the solvent is preferably selected from at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, alcohol, acetone, water, toluene, xylene, methyl acetate, and ethyl acetate, and more preferably selected from at least one of N-methylpyrrolidone, dimethylformamide, alcohol, acetone, and water.
According to the present invention, in the step (3), the ratio of the solvent used in the ultrasonic peeling treatment to the product obtained in the step (2) is not particularly limited as long as the product obtained in the step (2) can be immersed in the solvent to ensure that the solvent can disperse the product obtained in the step (2), and in the present invention, preferably, the solvent is used in an amount of preferably 200-.
According to the present invention, in step (3), the conditions of the ultrasonic peeling treatment generally include: the temperature is 35-75 ℃ and the time is 1-6 hours. In addition, in the present invention, the apparatus for performing ultrasound is not particularly limited and may be conventionally selected by those skilled in the art.
According to the present invention, preferably, the method further comprises the steps of performing solid-liquid separation after the ultrasonic exfoliation treatment to obtain graphene, and washing and drying the graphene. The solid-liquid separation method is a method worked by a person skilled in the art, and comprises suction filtration, centrifugation and the like. The specific method for washing and drying the graphene may be the same as that described above, and is not described herein again.
The invention also provides graphene prepared by the method.
The present invention will be described in detail below by way of examples.
Unless otherwise specified, various materials used below are commercially available.
The expansion factor determination method is referred to as GBT10698 and 1989 Expandable graphite.
The graphene nanopowder prepared in the following manner is graphene with an atomic layer of 1-10.
In the following examples, two decimal places were retained for the relative deviation in absorbance.
Example 1
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with the average particle size of 325 meshes and the carbon content of more than or equal to 99.99 percent with elemental sulfur in a reaction kettle, wherein the weight ratio of the graphite to the elemental sulfur is 1:50, contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing with 2 weight percent dilute hydrochloric acid for many times, washing with deionized water to be neutral, and drying for 2 hours at the temperature of 80 ℃. The expansion factor was 2.5.
(2) And (2) placing the graphite with the increased interlayer spacing obtained in the step (1) into a reaction kettle, introducing ozone (the volume concentration of the ozone is 50%, and the balance of oxygen), and contacting for 3 hours at the reaction temperature of 35 ℃, wherein the introduction amount of the ozone is 2 times of the theoretical dosage used for decomposing the intercalating agent.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanosheets prepared in the embodiment into graphene aqueous dispersion with the content of 0.2 weight per thousand, standing for 1h, preparing dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand by taking the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values of S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.23%, 0.23% and 0.24% respectively. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 0.55%, 0.56% and 0.65%, respectively.
The raman spectrum and the transmission electron microscope of the graphene nano powder prepared in this example are shown in fig. 1 and fig. 2, respectively.
Specifically, as shown in (a) of FIG. 1, ID/IGThe value of 0.79 indicates that the prepared graphene has low graphitization degree and high exfoliation degree. As can be seen from fig. 2, graphene is transparent and thin sheet-like, has a small sheet size, is an oligo-layer graphene, and thus has good water solubility.
Example 2
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with the average particle size of 325 meshes and the carbon content of more than or equal to 99.99 percent with carbon disulfide in a reaction kettle, wherein the weight ratio of the graphite to the carbon disulfide is 1:50, contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing with 2 weight percent dilute hydrochloric acid for many times, washing with deionized water to be neutral, and drying for 2 hours at the temperature of 80 ℃. The expansion factor was 2.
(2) And (2) placing the graphite with the increased interlayer spacing obtained in the step (1) into a reaction kettle, introducing ozone (the volume concentration of the ozone is 50%, and the balance of oxygen), and contacting for 3 hours at the reaction temperature of 35 ℃, wherein the introduction amount of the ozone is 2 times of the theoretical dosage used for decomposing the intercalating agent.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanopowder prepared in the embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing 8 wt% per thousand dimethyl sulfoxide solutions from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the 8 wt% per thousand dimethyl sulfoxide solutions of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values between S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.95%, 0.99% and 1.06% respectively. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 1.62%, 1.75% and 1.83%, respectively.
Example 3
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with the average particle size of 325 meshes and the carbon content of more than or equal to 99.99 percent and phosphorus powder in a reaction kettle, wherein the weight ratio of the graphite to the phosphorus powder is 1:50, contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing with 2 weight percent dilute hydrochloric acid for many times, washing with deionized water to be neutral, and drying for 2 hours at the temperature of 80 ℃. The expansion factor was 2.
(2) And (2) placing the graphite with the increased interlayer spacing obtained in the step (1) into a reaction kettle, introducing ozone (the volume concentration of the ozone is 50%, and the balance of oxygen), and contacting for 3 hours at the reaction temperature of 35 ℃, wherein the introduction amount of the ozone is 2 times of the theoretical dosage used for decomposing the intercalating agent.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanopowder prepared in the embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing 8 wt% per thousand dimethyl sulfoxide solutions from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the 8 wt% per thousand dimethyl sulfoxide solutions of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values between S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.35%, 0.36% and 0.37% respectively. After standing still for 24 hours again, the numbers of DS1, DS2 and DS3 were measured 10 times and found to be 0.77%, 0.82% and 0.90%, respectively.
Example 4
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with the average particle size of 325 meshes and the carbon content of more than or equal to 99.99 percent with sulfur powder in a reaction kettle, wherein the weight ratio of the graphite to the sulfur powder is 1:50, contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing with 2 weight percent dilute hydrochloric acid for many times, washing with deionized water to be neutral, and drying for 2 hours at the temperature of 80 ℃. The expansion factor was 2.5.
(2) And (2) placing the graphite with the increased interlayer spacing obtained in the step (1) into a reaction kettle, introducing oxygen (with the purity of 100%), and contacting for 5 hours at the reaction temperature of 400 ℃, wherein the introduction amount of the oxygen is 5 times of the theoretical amount used for decomposing the intercalation agent.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanosheets prepared in the embodiment into graphene aqueous dispersion with the content of 0.2 weight per thousand, standing for 1h, preparing dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand by taking the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values of S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.55%, 0.63% and 0.65% respectively. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 1.02%, 1.25% and 1.45%, respectively.
The raman spectrum and the transmission electron microscope of the graphene nano powder prepared in this example are shown in fig. 1 and fig. 3, respectively.
Specifically, as shown in (b) of FIG. 1, ID/IG0.22, indicating that although oxygen has some oxidizing effect on the intercalated graphite, graphene has a higher degree of graphitization.
As can be seen from fig. 3, the graphene is in a sheet shape and has a larger sheet size, and the microstructure thereof indicates that the graphene can be peeled off at a higher degree, but the graphitization degree is higher, and the water solubility is not optimal.
Example 5
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with the average particle size of 325 meshes and the carbon content of more than or equal to 99.99 percent with sulfur powder in a reaction kettle, wherein the weight ratio of the graphite to the sulfur powder is 1:50, contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing with 10 weight percent dilute hydrochloric acid for many times, washing with deionized water to be neutral, and drying for 2 hours at the temperature of 80 ℃. The expansion factor was 2.5.
(2) And (2) uniformly mixing the graphite with the increased interlayer spacing obtained in the step (1) and aqueous hydrogen peroxide (with the mass percent concentration of 30%) in a reaction kettle at the stirring speed of 300 revolutions per minute, and contacting for 2 hours at the reaction temperature of 60 ℃, wherein the weight ratio of the graphite to the hydrogen peroxide (solute) is 1: 1.25.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanopowder prepared in the embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing 8 wt% per thousand dimethyl sulfoxide solutions from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the 8 wt% per thousand dimethyl sulfoxide solutions of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values between S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentage of the ratio of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement was 0.24% for DS1, 0.25% for DS2, and 0.25% for DS 3. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 0.67%, 0.73% and 0.78%, respectively.
The raman spectrum and the transmission electron microscope of the graphene nano powder prepared in this example are shown in fig. 1 and fig. 4, respectively.
Specifically, as shown in (c) of FIG. 1, ID/IGThe value of 0.76 indicates that the prepared graphene has a low graphitization degree.
As can be seen from fig. 4, the graphene is in a transparent sheet shape, has a small sheet size, is an oligo-layer graphene, and shows that the degree of exfoliation of the graphene is increased, and the water solubility is better.
Example 6
This example is intended to illustrate the process for preparing graphene provided by the present invention.
(1) Under the stirring speed of 300 revolutions per minute, uniformly mixing natural crystalline flake graphite with 325 meshes and carbon content of more than or equal to 99.99 percent, elemental sulfur and hydrazine hydrate in a reaction kettle, wherein the weight ratio of the graphite to the total amount of the elemental sulfur and the hydrazine hydrate is 1:50 (the mass ratio of the elemental sulfur to the hydrazine hydrate is 1:0.5), contacting for 10 hours at the reaction temperature of 150 ℃, transferring a reaction product into suction filtration equipment after the reaction is finished and cooled to room temperature, washing the reaction product with 2 weight percent dilute hydrochloric acid for multiple times, washing the reaction product with deionized water to be neutral, and drying the reaction product for 2 hours at the temperature of 80 ℃. The expansion factor was 2.5.
(2) And (2) placing the graphite with the increased interlayer spacing obtained in the step (1) into a reaction kettle, introducing ozone (the volume concentration of the ozone is 50%, and the balance of oxygen), and contacting for 3 hours at the reaction temperature of 35 ℃, wherein the introduction amount of the ozone is 2 times of the theoretical dosage used for decomposing the intercalating agent.
(3) And (3) carrying out ultrasonic treatment on the product obtained in the step (2) in an N-methylpyrrolidone solvent for 4 hours at the temperature of 40 ℃, wherein the dosage of the solvent is 1000ml relative to 1g of the product obtained in the step (2). And transferring the reaction product to suction filtration equipment for solid-liquid separation, and drying at 80 ℃ for 2h to obtain the graphene nano powder.
Preparing the graphene nanosheets prepared in the embodiment into graphene aqueous dispersion with the content of 0.2 weight per thousand, standing for 1h, preparing dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand by taking the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the dimethyl sulfoxide dissolving solutions with the concentration of 8 weight per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values of S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.22%, 0.21% and 0.21% respectively. After standing still for 24 hours again, the numbers of DS1, DS2 and DS3 were measured 10 times and found to be 0.58%, 0.62% and 0.73%, respectively.
Example 7
This example is intended to illustrate the process for preparing graphene provided by the present invention.
Graphene was prepared according to the method of example 1, except that crystalline graphite was used instead of flake graphite in example 1, and hydrazine hydrate was used instead of sulfur powder as an intercalator.
Preparing the graphene nanopowder prepared in this embodiment into 0.2 wt% per thousand graphene aqueous dispersion, standing for 1h, preparing 6 wt% per thousand oleic acid solution from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, and measuring the absorbance of the 6 wt% per thousand oleic acid solution of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, wherein the absolute values of the difference between S1 or S2 or S3 and the average value of S1, S2 and S3 in this measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement are 0.38%, 0.39% and 0.40% respectively. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 0.76%, 0.87% and 0.96%, respectively.
Example 8
This example is intended to illustrate the process for preparing graphene provided by the present invention.
Graphene was prepared according to the method of example 5, except that crystalline graphite was substituted for the crystalline flake graphite of example 5, the oxidant was substituted for the hydrogen peroxide with benzoyl peroxide, and the oxidative contact reaction conditions included: the reaction temperature was 100 ℃ and the reaction time was 6 hours.
Preparing the graphene nanopowder prepared in this embodiment into 0.2 wt% per thousand graphene aqueous dispersion, standing for 1h, preparing 6 wt% per thousand oleic acid solution from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, and measuring the absorbance of the 6 wt% per thousand oleic acid solution of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, wherein the absolute values of the difference between S1 or S2 or S3 and the average value of S1, S2 and S3 in this measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2 and RS3 to the average of S1, S2 and S3 in this measurement are 0.26%, 0.28% and 0.28% respectively. After standing still for 24 hours again, the numbers of DS1, DS2 and DS3 were measured 10 times and found to be 0.78%, 0.83% and 0.88%, respectively.
Example 9
This example is intended to illustrate the process for preparing graphene provided by the present invention.
Graphene was prepared according to the method of example 1, except that the flake graphite in example 1 was replaced with synthetic graphite.
Preparing the graphene nanopowder prepared in this embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand from the graphene aqueous dispersions at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, determining the absorbances of the N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and determining for 10 times, wherein the absolute values of the differences between S1 or S2 or S3 and the average values of S1, S2 and S3 in the determination are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement are 0.24%, 0.24% and 0.24% respectively. After standing still for 24 hours again, the numbers of DS1, DS2 and DS3 were measured 10 times and found to be 0.58%, 0.60% and 0.62%, respectively.
Example 10
This example is intended to illustrate the process for preparing graphene provided by the present invention.
Graphene was prepared according to the method of example 3, except that the intercalant used a mixture of phosphorus and sulfur powders in a weight ratio of 1:1.
Preparing the graphene nanopowder prepared in this embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand from the graphene aqueous dispersions at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, determining the absorbances of the N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and determining for 10 times, wherein the absolute values of the differences between S1 or S2 or S3 and the average values of S1, S2 and S3 in the determination are RS1, RS2 and RS 3. The percentage of the ratio of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement was 0.32% for DS1, 0.32% for DS2, and 0.32% for DS 3. After standing for 24 hours again, the samples were measured 10 times, and the ranges of DS1, DS2, and DS3 were 0.72%, 0.75%, and 0.80%, respectively.
Example 11
This example is intended to illustrate the process for preparing graphene provided by the present invention.
Graphene was prepared according to the method of example 2, except that the oxidant was nitric acid (concentration of 40% by mass, mass ratio of nitric acid to graphite 5: 1).
Preparing the graphene nanopowder prepared in this embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand from the graphene aqueous dispersions at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, determining the absorbances of the N-methylpyrrolidone solutions with a concentration of 10 wt% per thousand of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and determining for 10 times, wherein the absolute values of the differences between S1 or S2 or S3 and the average values of S1, S2 and S3 in the determination are RS1, RS2 and RS 3. The percentage of the ratio of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement was 2.58% DS1, 2.58% DS2, 2.58% DS 3. After standing for 24 hours again, the samples were measured 10 times, and the ranges of DS1, DS2 and DS3 were 3.29%, 3.76% and 4.14%, respectively.
Comparative example 1
This comparative example serves to illustrate the preparation of reference graphene.
Graphene was prepared according to the method of example 5, except that the intercalant was replaced with the same weight of ferric chloride for the sulfur powder.
Preparing the graphene nanopowder prepared in the embodiment into a graphene aqueous dispersion with a content of 0.2 wt% per thousand, standing for 1h, preparing 8 wt% per thousand dimethyl sulfoxide solutions from the graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively at 25 ℃, standing for 2h, measuring the absorbance of the 8 wt% per thousand dimethyl sulfoxide solutions of the prepared graphene aqueous dispersion at the upper part, the middle part and the bottom of the graphene aqueous dispersion respectively as S1, S2 and S3, and measuring for 10 times, wherein the absolute values of the difference values between S1 or S2 or S3 and the average values of S1, S2 and S3 in the measurement are RS1, RS2 and RS 3. The percentages DS1, DS2 and DS3 of the ratios of RS1, RS2, RS3 to the average of S1, S2, S3 in this measurement were 8.24%, 10.51% and 12.83% respectively. After standing for 24 hours again, the samples were measured 10 times, and the values of DS1, DS2 and DS3 were 16.33%, 19.62% and 25.08%, respectively.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (20)

1. The graphene is characterized in that graphene aqueous dispersions with the content of 0.02-2 weight per thousand are prepared and are stood, the absorbances of upper, middle and bottom graphene aqueous dispersions with the same volume and the same concentration of dissolved solutions with the same solvent are respectively measured at the same temperature, after the graphene aqueous dispersions are stood for 2 hours, the relative deviation of the absorbances of the upper, middle and bottom graphene aqueous dispersions is not higher than 5%, and after the graphene aqueous dispersions are stood for 24 hours, the relative deviation of the absorbances of the upper, middle and bottom graphene aqueous dispersions is not higher than 10%;
the preparation method of the graphene comprises the following steps:
(1) the graphite with increased interlayer spacing is obtained by contact reaction of graphite and an intercalating agent, wherein the intercalating agent is elemental sulfur or the combination of elemental sulfur and elemental phosphorus and/or hydrazine hydrate, and when the intercalating agent selects elemental sulfur to be combined with other intercalating agents for use, the mass ratio of the elemental sulfur to the total amount of the elemental phosphorus and the hydrazine hydrate is 1: 0.1-1; the conditions of the contact reaction include: the reaction temperature is 100-220 ℃, and the reaction time is 2-15 hours;
(2) contacting the graphite with increased interlayer spacing obtained in the step (1) with an oxidant, wherein the oxidant is selected from at least one of air, oxygen, ozone, chlorine dioxide, chlorine gas, hypochlorous acid, benzoyl peroxide and dicumyl peroxide;
(3) and (3) carrying out ultrasonic stripping treatment on the product obtained in the step (2).
2. The graphene according to claim 1, wherein the graphene aqueous dispersion is prepared in an amount of 0.02 to 2 wt% and left to stand, the absorbances of the same volume of the same solvent solutions of the same concentration of the upper, middle and bottom graphene aqueous dispersions are measured at the same temperature, respectively, the relative deviation of the absorbances of the solutions of the upper, middle and bottom graphene aqueous dispersions is less than or equal to 1% after 2 hours of standing, and the relative deviation of the absorbances of the solutions of the upper, middle and bottom graphene aqueous dispersions is less than or equal to 3% after 24 hours of standing.
3. The graphene according to claim 1, wherein the assay method comprises: respectively measuring the absorbances of the same solvent dissolving solutions with the same concentration of the upper graphene water dispersion liquid, the middle graphene water dispersion liquid and the bottom graphene water dispersion liquid with the same volume, respectively recording the absorbances as S1, S2, S3, S1 or S2 or S3 and the average value of S1, S2 and S3 in the measurement, recording the absolute values of the differences as RS1, RS2 and RS3, and recording the percentages of the ratios of RS1, RS2 and RS3 to the average value of S1, S2 and S3 in the measurement as DS1, DS2 and DS 3; standing for 2h, wherein the ranges of DS1, DS2 and DS3 are 0.1-2, 0.1-2 and 0.1-5 respectively; after standing for 24h, the ranges of DS1, DS2 and DS3 are 0.1-5, 0.1-5 and 0.1-10 respectively.
4. The graphene according to claim 3, wherein after standing for 2h, the ranges of DS1, DS2 and DS3 are 0.1-0.5, 0.1-0.5 and 0.1-0.8 respectively; after standing for 24h, the ranges of DS1, DS2 and DS3 are 0.1-1.5, 0.1-2 and 0.1-3 respectively.
5. The graphene according to any one of claims 1 to 4, wherein the measurement temperature is from ambient temperature to 100 ℃; the mass concentration of the solvent dissolving solution is 0.1-20 per mill; the solvent is selected from one or more of water, dimethyl sulfoxide, N-dimethylformamide, N-methylpyrrolidone, oleic acid and naphthenic acid; the number of times of measurement is 3-20.
6. The graphene according to claim 5, wherein the measurement temperature is 20-60 ℃; the mass concentration of the solvent dissolving solution is 0.2-10 per mill; the number of times of measurement is 5-10.
7. A preparation method of graphene is characterized by comprising the following steps:
(1) the graphite with increased interlayer spacing is obtained by contact reaction of graphite and an intercalating agent, wherein the intercalating agent is elemental sulfur or the combination of elemental sulfur and elemental phosphorus and/or hydrazine hydrate, and when the intercalating agent selects elemental sulfur to be combined with other intercalating agents for use, the mass ratio of the elemental sulfur to the total amount of the elemental phosphorus and the hydrazine hydrate is 1: 0.1-1; the conditions of the contact reaction include: the reaction temperature is 100-220 ℃, and the reaction time is 2-15 hours;
(2) contacting the graphite with increased interlayer spacing obtained in the step (1) with an oxidant, wherein the oxidant is selected from at least one of air, oxygen, ozone, chlorine dioxide, chlorine gas, hypochlorous acid, benzoyl peroxide and dicumyl peroxide;
(3) and (3) carrying out ultrasonic stripping treatment on the product obtained in the step (2).
8. The preparation method according to claim 7, wherein in the step (1), the mass ratio of the intercalation agent to graphite is 5-120: 1.
9. The preparation method according to claim 8, wherein in the step (1), the mass ratio of the intercalation agent to graphite is 10-100: 1.
10. The production method according to claim 7, wherein in the step (1), the conditions of the contact reaction include: the reaction temperature is 120-200 ℃ and the reaction time is 4-12 hours.
11. The method of claim 10, wherein the contacting is performed under agitation.
12. The production method according to claim 7, wherein in the step (1), the graphite is one or more selected from the group consisting of flake graphite, microcrystalline graphite, and synthetic graphite, and has a carbon content of 99% by weight or more and an average particle size of 30 to 500 mesh.
13. The production method according to claim 12, wherein the graphite has a carbon content of 99.99% by weight or more and an average particle size of 50 to 350 mesh.
14. The production method according to claim 7, wherein, in the step (2):
when the oxidant is air and/or oxygen, the contact reaction conditions comprise: the reaction temperature is 200-600 ℃, the reaction time is 0.1-8 hours, and the dosage of air and/or oxygen is 2-10 times of the theoretical value of oxygen demand for decomposing the intercalating agent by mass of the oxygen;
when the oxidant is one or more selected from ozone, chlorine and chlorine dioxide, the contact reaction conditions include: the reaction temperature is 20-100 ℃, the reaction time is 0.1-8 hours, and the dosage of one or more of ozone, chlorine and chlorine dioxide is 1-5 times of the theoretical dosage of the oxidant used for decomposing the intercalating agent;
when the oxidant is benzoyl peroxide and/or dicumyl peroxide, the contact reaction conditions comprise: the reaction temperature is 100-150 ℃, the reaction time is 4-12 hours, and the mass ratio of the oxidant to the graphite is 0.5-10: 1.
15. The production method according to claim 14, wherein in the step (2):
when the oxidant is air and/or oxygen, the contact reaction conditions comprise: the reaction temperature is 300-500 ℃, and the reaction time is 0.2-5 hours;
when the oxidant is one or more selected from ozone, chlorine and chlorine dioxide, the contact reaction conditions include: the reaction temperature is 30-80 ℃, and the reaction time is 0.2-4 hours;
when the oxidant is benzoyl peroxide and/or dicumyl peroxide, the contact reaction conditions comprise: the reaction temperature is 110-140 ℃, the reaction time is 5-10 hours, and the mass ratio of the oxidant to the graphite is 1-8: 1.
16. The method of claim 14 or 15, wherein the contacting is performed under agitation.
17. The production method according to claim 7, wherein, in the step (3), the ultrasonic peeling treatment is performed in a solvent selected from at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, alcohol, acetone, water, toluene, xylene, and methyl acetate and ethyl acetate; the amount of the solvent used was 200-10000 ml relative to 1g of the product obtained in the step (2).
18. The production method according to claim 17, wherein the solvent is selected from at least one of N-methylpyrrolidone, dimethylformamide, alcohol, acetone, and water; the amount of the solvent used was 500-5000 ml relative to 1g of the product obtained in the step (2).
19. The production method according to claim 7, 17 or 18, wherein in step (3), the conditions of the ultrasonic peeling treatment include: the temperature is 35-75 ℃ and the time is 1-6 hours.
20. Graphene prepared by the method of any one of claims 7-19.
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CN116462191A (en) * 2023-01-19 2023-07-21 浙江澜沐浦科技有限公司 Method for preparing graphene

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101173673B1 (en) * 2011-05-09 2012-08-13 전자부품연구원 Carbon based anode materials for lithium ion capacitor and preparation method thereof
CN103395779A (en) * 2013-08-15 2013-11-20 中国科学院宁波材料技术与工程研究所 Porous graphene and preparation method thereof
CN104058396A (en) * 2014-07-14 2014-09-24 复旦大学 Method for preparing large-size high-quality graphene with controllable number of layers
CN105293476A (en) * 2015-11-16 2016-02-03 复旦大学 Preparation method of large-size graphene oxide or graphene
CN106882796A (en) * 2017-03-23 2017-06-23 复旦大学 A kind of preparation method of three-dimensional grapheme structure/high-quality graphene
CN107271386A (en) * 2017-06-12 2017-10-20 常州第六元素材料科技股份有限公司 A kind of method for setting up graphene Stability of Slurry characterization model

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101173673B1 (en) * 2011-05-09 2012-08-13 전자부품연구원 Carbon based anode materials for lithium ion capacitor and preparation method thereof
CN103395779A (en) * 2013-08-15 2013-11-20 中国科学院宁波材料技术与工程研究所 Porous graphene and preparation method thereof
CN104058396A (en) * 2014-07-14 2014-09-24 复旦大学 Method for preparing large-size high-quality graphene with controllable number of layers
CN105293476A (en) * 2015-11-16 2016-02-03 复旦大学 Preparation method of large-size graphene oxide or graphene
CN106882796A (en) * 2017-03-23 2017-06-23 复旦大学 A kind of preparation method of three-dimensional grapheme structure/high-quality graphene
CN107271386A (en) * 2017-06-12 2017-10-20 常州第六元素材料科技股份有限公司 A kind of method for setting up graphene Stability of Slurry characterization model

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
The effect of hydrazine intercalation on the structure and capacitance of 2D titanium carbide (MXene);O. Mashtalir et al.;《Nanoscale》;20161231;第8卷;9128-9133 *

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