CN108529607B - Preparation method of graphene - Google Patents

Preparation method of graphene Download PDF

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CN108529607B
CN108529607B CN201810054862.0A CN201810054862A CN108529607B CN 108529607 B CN108529607 B CN 108529607B CN 201810054862 A CN201810054862 A CN 201810054862A CN 108529607 B CN108529607 B CN 108529607B
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graphene
graphite
stripping
aromatic amine
ultrasonic treatment
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CN108529607A (en
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黄美荣
李新贵
于佳雪
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Tongji University
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    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00Structure or properties of graphene
    • C01B2204/20Graphene characterized by its properties
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Abstract

The invention relates to a preparation method of graphene, which comprises the steps of placing graphite in aromatic amine, carrying out continuous ultrasonic treatment or multi-round ultrasonic treatment after replacing fresh aromatic amine, and carrying out centrifugal separation on a product to obtain the graphene. Compared with the prior art, the liquid-phase stripping of the graphene can be completed at room temperature only by ultrasonic action, other energy-consuming processes are not involved, the preparation process is simple and convenient, the cost is relatively low, 100% stripping of the graphite can be realized through a limited number of stripping wheels in a stripping system with the graphite content of not more than 1.5mg/mL, and the obtained graphene is pure and high in quality. The perfect electronic structure, particularly the pure graphene without solvent residues, can keep the inherent characteristics of the graphene, so that the graphene plays an irreplaceable role in various fields such as nano composite materials, large solar cells, lithium battery electrodes, super capacitors, light emitting diodes, field effect transistors, liquid crystal display devices, flexible touch screens and the like, and is expected to be widely used in various industries.

Description

Preparation method of graphene
Technical Field
The invention relates to a graphene preparation method, and belongs to the technical field of graphene preparation.
Background
Since geosel K S, geom a K, Morozov S V, Jiang D, Zhang Y, Dubonos S V, grigiova I V, firstov a.a. electric field effect in atomic carbon films science,2004,306(5696):666-669, single-layer graphene sheets at atomic level were prepared by micromechanical lift-off method from geosel K S and Novoselov, university of british, 2004, it became a hot spot of competitive research overnight due to its low material cost and excellent electrical properties. Graphene is used as a star-grade material, is taken as a chelating point in a plurality of new materials, becomes a new research bright point in the fields of materials and physical science, arouses great attention and research of students at all levels all over the world, and has an unprecedented research enthusiasm. The single-layer two-dimensional graphene is a universal building block made of carbon-based materials and is a matrix of graphite forms of other dimensions. The curling can construct a zero-dimensional buckyball (buckyball) and a plurality of other non-tubular fullerenes and one-dimensional carbon nanotubes which are stacked on the carbon nanotubeTogether back to the three-dimensional graphite bulk material. The movement modes of electrons and holes of two-dimensional graphene are greatly different from those of common three-dimensional graphite, but are the same as those of relativistic particles. Their excellent crystalline quality and electronic properties make them display performance levels that are difficult to achieve with conventional materials (Peng H S, Chen D Y, Huang J Y, Chikkannanavar S B, Hanisch J, Jain M, Peterson D E, Doorn S K, Lu Y F, Zhu Y T, Jian X. Strong and guide colossal carbon tubes with walls of rectangle macro organisms. Phys. Rev. Lett.,2008,101: 145501). The theoretical specific surface area of, for example, graphene can be as high as about 2630m2The thermal conductivity can reach 5300W/(m.K), which is higher than that of carbon nano tube and diamond, the mechanical property can reach 1060GPa, and the electron mobility can reach 15000-60000 cm at normal temperature2V.s, transmittance 97.7%, conductivity up to 106S/cm, perfect quantum tunneling effect and half-integer quantum Hall effect. Micron-scale graphene films are sufficiently rigid to not curl or fold as flexible fabrics, but rather have a large load capacity to carry millions of objects over their own weight (book T J, Blake P, Nair R, Jiang D, Hill E W, Bangert U, Blelch A, Gass M, Novoseov K S, Katsnelson M I, Geim A K. Macroscopic graphene membranes and the infrared barrier. Nano Lett, 2008, 8(8):2442 and 2446). And the graphene derivatives modified by various molecules or functional groups are possible to develop more new functions. Due to the unique properties, the material has wide application prospect in the fields of solar cells, light-emitting diodes, transparent electrodes for replacing ITO and FTO, liquid crystal display devices, large-scale pattern telescopic electrodes, electrode materials of lithium ion batteries, electrochemical capacitors, field effect transistors, memories, sensors and electrochemical biosensors, anticorrosive coatings, hydrogen storage materials, high-activity biomimetic oxidation catalysts, methanol fuel cell catalysts, various composite materials and the like, and almost the material cannot be used. Particularly, a field effect transistor made of graphene in a high-frequency circuit is expected to replace the existing mainstream silicon transistor, so that the high frequency of various electronic equipment instruments such as a super computer is promoted to be infinitely wide. Terahertz spectrum with novel development and research in whole electromagnetic spectrumRegional graphene also has great utility. The adjustable forbidden band is related to the characteristic that the forbidden band is adjustable, and the forbidden band of 0-3 eV (Brey L, Fertig H A. electronic states of graphene nanoribbon absorbed with the dielectric equalization. Phys. Rev. B2006, 73(23):235411) can be designed by cutting the graphene into micron or nanometer band, so as to just cover 1-10 THz terahertz frequency bands (Ju L, Geng B, Horng J, Girit C, Martin M, Hao Z, Bechtel HA, Liang X, Zettl A, Shen Y R, WaF. graphene planarity for tunable terahertz electromagnetic materials. Nat. Nanotechnol.2011,6: 634). This adjustable bandgap makes it promising for applications in terahertz emitters and detectors. The multifaceted and multipurpose graphene is expected to be developed into a novel multifunctional material following high-aromatic and high-heat-resistant organic materials such as carbon nanotubes, conductive polymers, conjugated polymers and the like.
In two major preparation methods of graphene, from Bottom to Top (Bottom-Up) and from Top to Bottom (Top-Down), the former mainly involves a micromachining technical approach, is easy to prepare, can also prepare single-layer and few-layer graphene with higher quality, but has harsh conditions (high temperature and high vacuum) and is difficult to produce in quantity. The latter uses graphite as raw material, and prepares graphene through intercalation, liquid phase stripping, oxidation reduction and other ways, and has mass production potential. The liquid phase stripping method has the advantages of low preparation cost, simple and easy operation, few defects of the obtained graphene and the like, and is highly concerned. The liquid phase exfoliation method is a method in which graphite is exfoliated in a liquid phase medium by means of ultrasonic waves, microwaves, shear forces, thermal stress, electrochemistry, and the like. The liquid phase stripping method mainly considers how to overcome van der waals force between graphite layers to achieve the purpose of stripping the graphene wafer. With the progress of liquid phase stripping research, two main categories of direct liquid phase stripping methods and auxiliary agent assisted liquid phase stripping methods have been derived from liquid phase stripping methods. The latter is a green aqueous stripping system which has been attracting attention in recent years, but because of the extremely large surface energy of water, it is necessary to add an auxiliary agent such as a surfactant like SDS, a polycyclic compound like sodium carboxymethyl cellulose, chitosan, epoxy resin, etc., porphyrin, pyrene, etc., and sodium silicate, sodium aluminate, sodium hydroxide, etc., and the stripping efficiency is not high, and the aqueous stripping system often needs to undergo a hydrothermal process at 200 ℃ in an autoclave (chinese patent 201110456632.5).
The direct liquid phase exfoliation method is a method of direct exfoliation using pure organic solvent, multi-component mixed organic solvent (chinese patent 201110428499.2) or ionic liquid (zhangping spectroscopy and spectral analysis 2016, 36(10): 231-. The Coleman study is representative of this field of study. He summarized the effect of organic solvent surface energy on exfoliation graphite efficiency, indicating that the surface tension of an effective exfoliation solvent should be close to 40mJ/m2The value is similar to the surface energy of graphene, so that the energy required for stripping graphite is close to zero, and the graphene is easy to strip. Further, the direct liquid phase exfoliation method is intended to obtain graphene with higher concentration, and the total Hildebrand solubility parameter t of the graphene is 23MPa1/2Wherein the three components of the Hansen solubility parameter are: dispersion force component 18MPa1/2Polar component 9.3MPa1/2Hydrogen bond force component 7.7MPa1/2(HernandezY, NicoloSev, Lotya M, et al. high-yield production of graphene by liquid-phase evolution of graphene. Nature Nanotechnology 2008,3: 563-568; colour JN. liquid evolution of defect-Free graphene. Account Chemical Research 2013,46(1): 14-22). These studies provide quantitative guidelines for the search for exfoliation solvents for graphite.
However, the classical organic solvents have so far been limited to N-methylpyrrolidone (NMP), a single solvent, and the drawbacks of NMP are evident. The graphene film has a high boiling point and a low vapor pressure and cannot be completely removed in a stripping system, NMP remained in graphene enables the conductivity of the graphene film which is dried in vacuum at room temperature to be only 0.05S/cm, the conductivity can be improved to 50S/cm after being dried in 300 ℃ atmosphere for 2H, and the conductivity can be improved to 65S/cm after being dried in 250 ℃ Ar/H2 for 2H. Even under such severe drying conditions, NMP bound to graphene nanoplatelets cannot be completely removed, and about 10% of NMP remains, corresponding to 1 NMP molecule per 75 graphene carbons, which are trapped on the inner surface of graphene (Hernandez Y, nicolosiv, type M, et al, high-yield process of graphene byyliquid-phase evolution of graphene. nature Nanotechnology 2008,3: 563-568). Undoubtedly, such NMP-remaining graphene causes great limitations in further use. Some methods using NMP as a stripping solvent need to increase a solvothermal process to enhance an ultrasonic stripping effect, but the prepared graphene is thick, cannot be completely stripped, and cannot obtain high-quality graphene (chinese patent 201310169706.6); for organic solvents N, N-Dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) which have similar Hansen solubility dispersion component and slightly larger Hilbert-Blard total parameter value with NMP, the stripping yield is only about 1 wt%, and the efficiency is extremely low; while the stripping in acetonitrile solvent can be successfully completed after pretreatment for 12h at 180 ℃ by a solvothermal method in an autoclave in advance, and the stripping yield is only 10-12 wt% (Qian W. Hao R, Hou Y. L. et. Solvothermal-associated isolation process stone with high yield and high quality. Nano Res 2009,2: 706. 712); the aliphatic organic amine solvent stripping can be finished after being pretreated for 72 hours at 170-250 ℃ by a solvothermal method in an autoclave, the stripping efficiency is very low, and the concentration of the obtained graphene is only dozens of mu g/mL-150 mu g/mL (Chinese patent, 200910093581.7); perfluorinated aromatic organic solvents such as pentafluorobenzonitrile, hexafluorobenzene, and trifluoromethyl hexafluorobenzene, etc. can obtain graphene only by 1h of sonication, but the exfoliation yield is still only 1 wt% to 2 wt%, and perfluorinated aromatic organic solvents are expensive and very corrosive (Bourlinos A B, Georgaikias V, Zboril R, et al. liquid-phase ionization of graphite towards dissolved graphene. Small 2009,5(16): 1841-1845). Recently, the use of C3-C8 alcoholic solvents such as isoamyl alcohol, butanol and octanol has been disclosed, which is characterized by the availability of single-layer graphene, but it requires the prior intercalation of phosphoric acid molecules, which requires several months of time to be maintained at 90 ℃ (Kovtyukhova N I, Perea-Lopez N, Terrones M, ethyl. alumina in layers of graphene and hexagonal boron nitride film morphology evolution of the anode phosphorus interaction composition ACS Nano2017,11,6746 and 6754), which is very energy-consuming and time-consuming.
It can be seen that although many solvent systems have been used for liquid phase exfoliation of graphene. However, all the media cannot give consideration to the characteristics of simple operation, high yield, low cost, mass production, high quality and the like. Therefore, the preparation method for obtaining the high-quality graphene without solvent residues in a large scale, which is simple and feasible, has important significance.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of graphene. The preparation method provided by the invention is economic and effective, has a simple process, can be carried out in a large scale, and simultaneously has no solvent residue, and the prepared graphene has high quality.
The purpose of the invention can be realized by the following technical scheme:
a preparation method of graphene comprises the steps of putting graphite into aromatic amine, carrying out continuous ultrasonic treatment or multi-round ultrasonic treatment after replacing fresh aromatic amine, and carrying out centrifugal separation on a product to obtain the graphene.
In one embodiment of the present invention, the aromatic amine is selected from one of aniline, o-toluidine, m-toluidine, p-toluidine, o-ethylaniline, m-ethylaniline, p-ethylaniline, o-propylaniline, m-propylaniline, p-propylaniline, N-methylaniline, N-ethylaniline, N-propylaniline, or a binary or multicomponent blend solvent thereof.
In one embodiment of the invention, the graphite is natural flake graphite or expandable graphite, preferably expandable graphite.
In one embodiment of the invention, the ratio of the graphite to the aromatic amine is not more than 10/1(mg/mL), preferably 1/1 (mg/mL).
In one embodiment of the invention, before the continuous ultrasonic treatment or the replacement of fresh aromatic amine, the graphite is placed in the aromatic amine and then is subjected to a sealing soaking step.
In one embodiment of the invention, the graphite is placed in aromatic amine and sealed for a soaking time of 1 to 60 days, preferably 7 days.
In one embodiment of the invention, the graphite is placed in an aromatic amine at a temperature of from room temperature to 60 ℃, preferably room temperature.
In one embodiment of the invention, the temperature of the sonication is between room temperature and 60 ℃, preferably 40 ℃.
In one embodiment of the invention, the ultrasound mode is rod ultrasound or water bath ultrasound, preferably water bath ultrasound.
In one embodiment of the invention the ultrasound frequency is in the range of 20kHz to 70kHz, preferably 53 kHz.
In one embodiment of the invention, the continuous ultrasound time is 1h to 200h, depending on the initial concentration of graphite. The higher the initial concentration, the longer the sonication time.
In one embodiment of the invention, replacing fresh aromatic amine for multiple rounds of ultrasound refers to replacing fresh aromatic amine solvent for graphene after sealing and soaking, then performing ultrasound again, centrifuging after ultrasound, taking out graphite, adding new aromatic amine solvent again for re-ultrasound, and repeating the operations for multiple rounds of ultrasound, wherein the number of times of the multiple rounds of ultrasound is 2-20 times, and is determined according to the initial concentration of graphite. The higher the initial concentration, the more the number of the ultrasonic rounds, and the repeated operation can completely strip the graphite.
In one embodiment of the present invention, a graphene dispersion is obtained by: centrifuging the system after ultrasonic treatment at 200-1000 rpm for 30-120 min, and sucking and collecting supernatant to obtain the graphene dispersion.
In one embodiment of the present invention, the graphene dispersion is centrifuged, the collected graphene is washed, and then frozen and dried to remove the residual aromatic amine, thereby obtaining powdered graphene.
Preferably, the manner of obtaining the powdered graphene is: centrifuging the graphene dispersion liquid at 7000 rpm-10000 rpm for 30 min-120 min, washing the collected graphene with deionized water and ethanol, transferring the washed graphene into a cold trap of a freeze dryer, freezing for 8h, drying for 40h, and finally drying in a vacuum oven at 150 ℃ for 36h to completely remove the residual stripping solvent aromatic amine.
In one embodiment of the present invention, the ultraviolet spectroscopy of the graphene dispersion: diluting the obtained graphene dispersion liquid by using stripping solvent aromatic amine in a proper proportion, and then scanning ultraviolet visible light within the wavelength range of 200-1100 nm by using the stripping solvent aromatic amine as a reference solution;
and (3) determining the absorptivity of the graphene: and (3) measuring the absorbance of different graphene concentrations at 660nm light waves, plotting the absorbance against the concentration of the graphene, and performing linear fitting through an origin according to Lambert-beer law:
A=b C
in the formula, A is the absorbance under 660nm light wave, b is the optical path, C is the graphene concentration, and the absorption coefficient of the graphene can be calculated according to the slope of the fitted straight line.
And (3) measuring the conductivity of the graphene: the obtained graphene powder is pressed into a sheet with the thickness of tens of micrometers to hundreds of micrometers by using a press, and the conductivity of the graphene powder is tested by adopting a four-probe mode.
Compared with the prior art, the innovation points of the invention are embodied in the following aspects:
the method takes graphite as a raw material, the graphite is placed in an aromatic amine solvent to be stripped to prepare the graphene, the polar amino group on the aromatic amine molecule is fully utilized to develop an induction effect on intercalation between graphite layers, and the power supplied aromatic ring increases the pi electron density, so that the pi-pi electron effect between carbon atom layers in the graphite is promoted to be converted into the effect between two pi electrons with different conjugation degrees, namely a carbon atom layer and an organic solvent aromatic ring, the cohesive energy between graphene platelets is overcome, and finally the stripping of the graphite is realized. The graphene obtained by the stripping method not only has perfect sp2The electronic hybrid structure is easy to remove and has no solvent residue because the solvent has certain vapor pressure and proper boiling point. It is clear that such compositionally pure, heteroatom-free graphene is able to achieve the various properties that are inherent to graphene without being inhibited or affected as other residual solvent-bound graphene. The liquid phase stripping method of the present invention has not been reported.
The beneficial effects of the invention are embodied in the following aspects:
according to the method, an aromatic amine solvent is selected to carry out liquid phase stripping of graphite at room temperature, and the aromatic amine solvent is intercalated and stripped into single-layer graphene and few-layer graphene by utilizing the wettability and affinity between aromatic amine molecules and graphite. For an exfoliation system with an initial graphite concentration of 1.0mg/mL, almost complete exfoliation was achieved by a limited number of rounds of exfoliation. When the stripping peak period is reached during multi-round stripping, the obtained stripping system is centrifuged at 900rpm for 90min to 150min, and the concentration of graphene in the un-stripped graphite is thrown out to be 219 mu g/mL at most. According to different initial graphite consumption and different stripping process parameters, the absorption coefficient of the graphene to 660nm wavelength is 2840-5996L/(g.m), and the diluted graphene dispersion liquid has obvious Tyndall effect, all of which indicate that the graphite is stripped into few-layer graphene. Electron microscope observation further shows that the obtained graphene is few-layer graphene, and the transverse dimension of the graphene is in a micron order. The graphene dispersion system is stable, the settling time constant of the graphene dispersion system with the concentration of 17 mu g/mL is 65.4h, and the concentration C of the stably dispersed graphene0Is settleable graphene concentration C11.04 to 1.19 times of the amount of the graphene, that is, more than half of the graphene does not settle. And the aggregation of the settled graphene in the standing process is temporary soft aggregation and can be completely opened and recovered by ultrasonic. The solvent in the graphene dispersion liquid can be completely removed by washing and drying, so that the conductivity of the obtained powder graphene measured by a tabletting four-probe method reaches 38.5S/cm.
The liquid phase stripping of the graphene can be completed at room temperature only by ultrasonic action, other energy consumption processes are not involved, the preparation process is simple and convenient, the cost is relatively low, the stripping of most of graphite can be realized through a limited number of stripping rounds in a stripping system with the graphite content of not more than 1.5mg/mL, and the obtained graphene is pure and has high quality. The perfect electronic structure, especially the pure graphene without solvent residue, can keep the inherent characteristics of the graphene, such as ultrahigh electron mobility, ultrahigh electron conductivity and ion conductivity, ultrahigh heat conductivity, excellent light transmittance and the like, so that the graphene plays an irreplaceable role in various fields of nano composite materials, large solar cells, lithium battery electrodes, super capacitors, light emitting diodes, field effect transistors, liquid crystal display devices, flexible touch screens and the like, and is expected to be widely used in various industries.
Drawings
Fig. 1 shows an ultraviolet spectrum (a) and a corresponding digital photograph (b) of the graphene dispersion obtained in example 1;
fig. 2 shows an ultraviolet spectrum (a) and a corresponding digital photograph (b) of the graphene dispersion obtained in example 2;
fig. 3 shows the tyndall phenomenon (a) of the graphene dispersion obtained in example 7 and the tyndall phenomenon (b) not observed in the excessively concentrated graphene;
fig. 4(a) is an ultraviolet-visible spectrum of the graphene dispersion obtained in example 9 after 6-fold dilution;
fig. 4(b) is an ultraviolet-visible spectrum of the graphene dispersion obtained in example 10 after 6-fold dilution;
fig. 4(c) is an ultraviolet-visible spectrum of the graphene dispersion obtained in example 11 after 6-fold dilution;
fig. 4(d) is an ultraviolet-visible spectrum of the graphene dispersion obtained in example 12 after 6-fold dilution;
fig. 4(e) is an ultraviolet-visible spectrum of the graphene dispersion obtained in example 13 after 6-fold dilution;
FIG. 5 is a graph showing the relationship between A660 and the number of ultrasonic cycles of the graphene dispersion liquid obtained in examples 9 to 13 after 6-fold dilution;
FIG. 6 shows the relationship between the soaking time in example 6 and examples 9 to 12, and the number of cycles required for completely stripping graphite, the theoretically calculated concentration of the total graphene dispersion solution, and the actually measured A660 sum value in each cycle;
FIG. 7 is a graph showing a UV absorption spectrum of a supernatant obtained in example 14 diluted 6 times;
fig. 8 is a settling curve of the graphene obtained in example 17 and example 18;
fig. 9 is a raman spectrum of graphene obtained in example 3;
FIG. 10(a) is a SEM image of the graphene obtained in example 12 showing corrugated sheets;
FIG. 10(b) is a SEM photograph of the graphene obtained in example 12 showing a wrinkled porous structure;
fig. 10(c) is a scanning electron micrograph of the micron-sized graphene obtained in example 12;
fig. 11(a) is a transmission electron micrograph of few-layer graphene without stacking in the graphene obtained in example 16;
FIG. 11(b) is an electron diffraction pattern of a selected region of graphene in FIG. 11 (a);
FIG. 12 is a transmission electron micrograph of a single-layer graphene and a few-layer graphene obtained in example 16 stacked together, and the right image shows selected region electron diffraction patterns of the graphene in the left image of FIG. 12;
fig. 13 is a transmission electron micrograph of the few-layer graphene obtained in example 16 at the left, and a curled edge morphology of the graphene obtained in example 16 in an ethanol medium.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1
Rod type ultrasonic effect experiment
A small tube was charged with 20mg of graphite and 20mL of o-toluidine, at which point the initial concentration of graphite was 1.0 mg/mL. Rod-type ultrasound is carried out at 40% power by using a JY92-IIN ultrasonic cell crusher (650W, 20-25 kHz), ultrasound is carried out intermittently, the ultrasound is stopped for 1s every 3s, the total ultrasound is carried out for 1h and 4h, the ultraviolet spectrum of the graphene dispersion liquid obtained after 20 times of dilution after different ultrasound time is shown in figure 1(a), and the appearance photo and the Tyndall photo are shown in figure 1 (b). It can be seen that after 1h, especially 4h, of rod ultrasound, an ink-like graphene dispersion was obtained, whose uv spectrum produced significant absorption of 660nm light waves, but after a night of standing, the uv was again reduced and a small amount of particle settling was observed.
Example 2
Water bath ultrasonic effect experiment
A small tube was charged with 20mg of graphite and 20mL of o-toluidine, at which point the initial concentration of graphite was 1.0 mg/mL. It was placed in an SK3300HP ultrasonic cleaner (180W,53kHz) and subjected to water bath ultrasound at 100% power for 33h in total. The ultraviolet map of the graphene dispersion liquid obtained under several ultrasonic time nodes after 11 times dilution is shown in figure 2(a), and the appearance photo and the tyndall photo are shown in figure 2 (b). It can be seen that the absorption of the ultraviolet spectrum to the light wave of 660nm is obviously increased with the extension of the ultrasonic time, which indicates that the concentration of the obtained graphene is increased with the extension of the ultrasonic time, and the absorption spectrum of the graphene dispersion liquid at the high wavelength is reduced after standing for a night, but the reduction range is obviously smaller than that of the rod-type ultrasonic in example 1. In this case, the number of graphene layers obtained is smaller, so that water bath ultrasound is superior to rod ultrasound.
Examples 3 to 4: experiment of drying mode
Example 3
10mg of expanded graphite and 20mL of m-ethylaniline were added to the cuvette, at which point the initial concentration of graphite was 0.5 mg/mL. Placing the mixture into an SK3300HP ultrasonic cleaning machine (180W,53kHz), and carrying out batch-mode water bath ultrasonic treatment for 48h at 100% power, wherein the temperature is controlled not to exceed 40 ℃. The exfoliation system was centrifuged at 900rpm for 45min to remove non-exfoliated graphite, the weight of the non-exfoliated graphite remaining on the centrifuge tube wall was 1.87mg after washing with alcohol and water and freeze-drying, and the weight loss was 1.35 mg after vacuum drying at 150 ℃ for 36h to completely remove the residual solvent.
Centrifuging the collected supernatant to obtain a dense black graphene dispersion, shaking the dense black graphene dispersion uniformly, diluting the graphene dispersion by 6 times with a solvent according to the volume ratio of 1:5, and scanning an ultraviolet spectrum to indicate that the absorbance A660 of the graphene dispersion to the wavelength of 660nm reaches 1.53. Centrifuging the supernatant at 10000rpm for 90min to settle graphene, washing with absolute ethyl alcohol for 5min by ultrasound, shaking for 2-3 times to remove organic solvent attached to the surface of the graphene by using the ethanol, collecting the cleaned graphene at 10000rpm for 90min, transferring the graphene to a glass surface dish, freezing for 8h, and freeze-drying for 40h to obtain black graphene powder 11.09mg, transferring the black graphene powder to a vacuum oven at 150 ℃ for drying for 36h to obtain black graphene powder 6.91mg, and calculating the concentration of the original graphene dispersion to be 0.3455mg/mL and the stripping yield to be 69.1%.
Example 4
The difference from example 3 is that the stripping solvent is replaced by a ternary blending solvent of aniline, N-methylaniline and m-toluidine with the same volume, and the stripping is carried out by soaking for 60 days at room temperature before ultrasonic treatment. And after ultrasonic treatment, collecting cleaned graphene at 10000rpm for 90min, transferring the graphene to a glass surface dish, freezing the graphene for 8h, and freeze-drying the graphene for 40h to obtain black graphene powder 9.27mg, transferring the black graphene powder to a vacuum oven at 150 ℃ for drying for 36h to obtain black graphene powder 5.67mg, and calculating the concentration of the original graphene dispersion liquid to be 0.2835mg/mL and the stripping yield to be 56.7%.
As can be seen from examples 3 and 4, the residual solvent can be removed to the maximum extent by increasing the vacuum drying.
Examples 5 to 6: multiple rounds of stripping at 1.0mg/mL
Example 5
An equal volume of a mixed solvent of 20mg graphite and 20mL aniline and N-ethyl aniline was added to the cuvette at an initial graphite concentration of 1.0 mg/mL. Placing the sample in an SK3300HP ultrasonic cleaning machine (180W,53kHz), performing water bath ultrasonic treatment at 100% power for 20h, peeling at the temperature of not more than 50 ℃, centrifuging at 800rpm for 60min after finishing peeling in the 1 st round, sucking 70% of supernatant liquid into a test tube, shaking uniformly, observing the Tyndall effect, taking out a little of supernatant liquid, diluting according to a ratio of 1:10, and performing ultraviolet-visible light scanning. And centrifuging at 10000rpm for 90min to collect all graphene, centrifuging and washing for 2 times by using ethanol, weighing after freeze drying and vacuum drying, and calculating the stripping rate and the graphene concentration of the 1 st round. Adding fresh mixed solvent to the settled un-stripped graphite at the bottom of the original bottle to strip for 20h in the 2 nd round; in this way, multiple rounds of exfoliation were performed until the non-exfoliated graphite could not be thrown out by centrifugation. The results show that the 4 rounds of exfoliation completed the complete exfoliation of the graphite. The weight, exfoliation rate, graphene concentration, and conductivity of the powder pressed graphene obtained in each run by the four-probe method are shown in table 1. The obtained stripping system is centrifuged at 800rpm for 60min, and the concentration of graphene in the un-stripped graphite is thrown out to reach 474 mug/mL. The light absorption coefficient of the graphene obtained by linear fitting according to the Lambert beer law according to the absorbance and corresponding concentration of each round of the graphene dispersion liquid after 11 times of dilution is 2841L/(g.m), wherein the linear correlation coefficient is 0.998, and the linear range is 10-15 mu g/mL. The graphene can be reflected to be few-layer graphene from the numerical value of the extinction coefficient.
Table 1 shows the stripping yield and concentration of graphene and the conductivity of graphene obtained by centrifuging at 800rpm for 60min after multiple rounds of stripping of graphite when the initial graphene concentration is 1.0mg/mL
Figure BDA0001553451100000101
Example 6
Multiple rounds of stripping were performed similarly, but a mixed solvent of aniline, p-ethylaniline and N-propylaniline (volume ratio 5:3:2) was used as a stripping mixed solvent. The exfoliation temperature did not exceed 40 ℃ and the non-exfoliated graphite was thrown off using a 900rpm centrifuge for 45 min. And diluting the obtained graphene dispersion liquid according to a ratio of 1:6, and then carrying out ultraviolet-visible light scanning. In the washing and drying stage, in order to improve the working efficiency, the graphene dispersion solutions with similar absorbance are combined and then subjected to washing and drying treatment. The results show that 10 rounds of exfoliation can complete exfoliation of the graphite. The weight, exfoliation rate and graphene concentration of the obtained graphene for each round are shown in table 2. The obtained stripping system is centrifuged at 900rpm for 90min, and the concentration of graphene in the un-stripped graphite is thrown out to be 298.5 mu g/mL at most. Due to the small sample size, the conductivity of the four-probe method for powder pressed graphene was only the combined sample of the 8 th and 9 th round and the sample of the 10th round, and the conductivity was 16S/cm and 19S/cm, respectively. And the absorption coefficient of graphene obtained by linear fitting according to the Lambert beer law according to the absorbance and corresponding concentration of each round of graphene dispersion liquid after 6 times of dilution is 4388L/(g.m), wherein the linear correlation coefficient is 0.931, and the linear range is 0.76-49.8 mu g/mL. The graphene can be reflected to be few-layer graphene from the numerical value of the extinction coefficient.
Table 2 shows the exfoliation yield and dispersion concentration of graphene obtained by centrifuging at 900rpm for 45min after multiple rounds of exfoliation of graphite when the initial graphene concentration is 1.0mg/mL
Figure BDA0001553451100000111
Examples 7 to 8: multiple rounds of Peel at 1.5mg/mL and 2.5mg/mL
30mg and 50mg of graphite and 20mL of a 1:1 blend solvent of aniline and N-propylaniline were added to 2 tubes, respectively, at initial concentrations of graphite of 1.5mg/mL and 2.5mg/mL, respectively, followed by ultrasonic washing as in example 6. Taking 1.5mg/mL as an example, from the graphene stripped in the 1 st round, the obtained graphene dispersion liquid is in a black ink shape, and an obvious tyndall phenomenon can be observed, as shown in fig. 3, as the number of stripping rounds increases, the concentration of the graphene gradually increases, and the tyndall phenomenon cannot be observed due to excessively concentrated graphene. When the multi-wheel stripping reaches the stripping peak, the obtained stripping system is centrifuged at 900rpm for 90min, and the concentration of graphene in the un-stripped graphite is thrown out to be 219 mu g/mL at most. The detailed results of the peeling of the front 14 wheels and the front 11 wheels are shown in Table 3. It can be seen that the number of the stripping rounds is greatly increased after the initial graphite concentration is increased, although 10 rounds of stripping cannot complete the stripping of all the graphene, for the multi-round stripping with the initial graphite concentration of 1.5mg/mL, 14 rounds of stripping can complete the stripping of most of the graphite, and the total stripping yield can reach 78.7%. The highest conductivity of the powder graphene measured by a tabletting four-probe method can reach 38.5S/cm.
In addition, the light absorption coefficient of graphene obtained by performing linear fitting according to Lambert beer's law on the basis of the absorbance and corresponding concentration of each 6-fold diluted graphene dispersion liquid for each round of graphene peeling from 1.5mg/mL and 2.5mg/mL is 5996L/(g.m), wherein the linear correlation coefficient is 0.995, and the linear range is 1.6-17 [ mu ] g/mL. The graphene can be reflected to be few-layer graphene from the numerical value of the extinction coefficient.
TABLE 3 exfoliation yield and dispersion concentration of graphene obtained by centrifugation at 900rpm for 90min after multiple rounds of exfoliation of graphite when initial graphene concentration was 1.5mg/mL and 2.5mg/mL, respectively
Figure BDA0001553451100000121
Examples 9 to 13: immersion pretreatment assisted liquid phase stripping
Pouring 5 parts of 20mg graphite into 5 test tubes, adding 20mL aniline,the cells were respectively sealed and soaked at room temperature for 2 days, 5 days, 7 days and 21 days and soaked at 60 ℃ for 7 days with stirring, and then subjected to multiple rounds of exfoliation, post-treatment of graphene, and the like according to example 6. The ultraviolet-visible spectrum of each round of exfoliated graphene dispersion liquid obtained under the 5 soaking conditions is shown in fig. 4(a), 4(b), 4(c), 4(d) and 4(e), and a diluted 6-fold amount of a can be seen660Up to 2. As the number of days of soaking at room temperature increased, the number of rounds required for total exfoliation decreased to 9, 8, 7 and 6 rounds in order. Not only the time was significantly shortened, but the amount of stripping solvent used was also gradually decreased from 165mL to 110mL, which was 33.3%. See table 4 for details. This indicates that the immersion pretreatment is favorable for intercalation and exfoliation of the exfoliation solvent, and improves exfoliation efficiency.
TABLE 4 Effect of the Pre-soak treatment on graphite exfoliation
Figure BDA0001553451100000131
Figure BDA0001553451100000141
On the other hand, the number of cycles in which the highest exfoliated graphene concentration appears is advanced from the concentration of the exfoliated graphene dispersion, and the graphite subjected to the immersion treatment for 7 days enters the exfoliation explosion period from the 4 th cycle and is diluted by 6 times of a660All above 1.2, see the bar chart of absorbance and number of ultrasound rounds (fig. 5). The longer the infiltration time, the earlier the highest point is reached. The effect of stirring and soaking for 7 days at 60 ℃ is close to that of soaking for 21 days at room temperature, which shows that the soaking treatment has time-temperature equivalence.
The relationship of soaking time to the number of cycles required to completely exfoliate the graphite for the same graphite soaked at room temperature is shown in fig. 6, where the data for 0 days of soaking is taken from example 6. Meanwhile, the total graphene dispersion concentration can be theoretically calculated under the condition of complete stripping according to the weight of the input initial graphite and the total volume of the solvent used in the stripping process. The concentration versus soaking time is also shown in fig. 6. It can be seen that the peel efficiency was high except for the un-soaked sampleLimited, only 14mL of dispersion can be taken out per stripping), the number of cycles required for complete stripping of graphite is significantly reduced as the soaking time is prolonged, while the concentration of the total graphene dispersion is significantly increased. If the soaking time is actually measured with the graphene dispersion liquid A in each round660The addition values are correlated, and each round of the addition values is found to measure A660The addition value was not increased, and the level was maintained substantially (fig. 6), and it is assumed that the number of graphene layers peeled off gradually decreased as the soaking time was increased, according to the rule that the number of graphene layers decreased and the absorption coefficient decreased. It can be seen that, from the viewpoint of both the peeling efficiency and the peeling effect, the soaking facilitates the wetting of the vermicular pore canal structure by the solvent, and even fully wets the graphite microcrystals through the capillary phenomenon of the vermicular pore canals, thereby promoting the peeling of the graphite.
Example 14: peeling off the bull wheel
20mg of graphite and 20mL of toluidine are poured into a test tube, the test tube is sealed and soaked for 2 months at room temperature, then a 480W ultrasonic cleaning machine is used for carrying out large-round ultrasonic treatment for a plurality of times at 40kHz for a long time period, stripping of most of graphite is completed after 4 rounds, residual graphite is negligible, the total stripping yield can reach 83.3% after 4 rounds of stripping, particularly after 1 st round of ultrasonic stripping and 2 nd round of ultrasonic stripping are completed at 40h and 80h time points, the ultraviolet absorption spectrum with 6-time dilution of supernatant fluid is centrifuged at 900rpm for 90min is shown in figure 7, A660 is 2.8556 and 2.4308, the corresponding graphite stripping yields respectively reach 42.6% and 40.7%, and the large-round stripping with increased time length can also prepare graphene with high yield.
Example 15: exfoliation of graphite under 50mL scale
Adding 2 parts of 50mg of graphene into two 100mL test tubes respectively, adding 50mL of mixed solvent of aniline and toluidine in a volume ratio of 3:2 respectively, placing the materials in an SK3300HP ultrasonic cleaning machine (180W and 60kHz), carrying out water bath ultrasonic treatment at 100% power, completing the first round of ultrasonic treatment after 60h, centrifuging at 900rpm for 90min, combining obtained supernatants, shaking up and diluting by 6 times, measuring UV, continuously adding solvent for stripping without stripping, centrifuging every 20h to obtain a supernatant, and similarly diluting by 6 times, wherein the results are shown in Table 5. The absorbance A of the supernatant after the second round of stripping was observed6602.4713 is achieved, 26.7mg of graphite which is not stripped after the 4 th round is remained, and the total stripping yield can reach 73.3% after the 4 th round stripping is completed, which shows that the graphene can be prepared with higher yield by enlarging the stripping scale.
TABLE 550 mL Scale graphite exfoliation results
Figure BDA0001553451100000151
Mixing all the stripped graphene dispersion solutions, uniformly mixing, taking 300mL, and carrying out ultrasonic treatment in 2 conical flasks for 30min to completely recover the graphene dispersion solutions; and (4) subpackaging the recovered graphene dispersion liquid into a centrifuge tube, and throwing out a small amount of non-peeled graphite after 90min at 900rpm and discarding the graphite. Centrifuging the supernatant at 1000rpm for 90 minutes, throwing out a graphene fraction of G900-1000, determining the absorbance by a stepwise dilution method after constant volume, washing the residual dispersion, drying and weighing, and calculating the concentration C of graphene in the mother solution1After linear fitting is carried out on the relation curve A to C, the obtained absorption coefficient is 4591L/(g.m), the fitting linear range is 2.0 to 31.9 mug/mL, and the linear correlation coefficient is 0.992.
Similarly, centrifuging the supernatant at 1000rpm for 90 minutes at 2000rpm to obtain a graphene fraction G2000-1000, diluting to constant volume, measuring absorbance by a stepwise dilution method, washing the residual dispersion, drying, weighing, and calculating the concentration C of graphene in the mother solution2After linear fitting is carried out on the relation curve A-C, the obtained absorption coefficient is 4180L/(g.m), the fitting linear range is 3.1-50.4 mu g/mL, and the linear correlation coefficient is 0.994.
Similarly, centrifuging the supernatant at 2000rpm for 90 minutes at 3000rpm, centrifuging the spun graphene fraction at G3000-2000, determining the absorbance by a stepwise dilution method after constant volume, washing the residual dispersion, drying, weighing, and calculating the concentration C of graphene in the mother solution3After linear fitting is carried out on the relation curve A to C, the obtained light absorption coefficient is 4126L/(g.m), the fitting linear range is 2.7-43.5 mu g/mL, and the linear correlation coefficient is 0.995.
It is found that the three graphene fractions G900-1000, G1000-2000 and G2000-3000 have absorption coefficients in the range of 4100-4600L/(g.m), and are few-layer graphene.
Example 16
20mg of graphite and 20mL of aniline are poured into a test tube, the test tube is soaked for 6 weeks at room temperature, then 4 rounds of ultrasound are carried out on the test tube by a 180W ultrasonic cleaning machine at 53kHz in 40h 1 round, each round of graphite is stripped, the graphite is centrifuged at 900rpm for 120min, and the non-stripped graphite is thrown out, wherein the total yield can reach 57.6 percent after 4 rounds of stripping. Combining the obtained supernatant, continuing to perform ultrasonic treatment for 33h, centrifuging at 900rpm for 120min, throwing out thicker graphene, and collecting the graphene fraction centrifuged at 1000-2000 rpm for 90 min.
Examples 17 to 18: investigation of the Settlement Curve
30mL of the graphene dispersion liquid obtained in examples 7 to 8 was transferred to a test tube, ultrasonic treatment was performed for 30min, the time after the ultrasonic treatment was t 0, and then the test tube was kept still, and natural sedimentation was followed and studied by visual observation, Tyndall effect and ultraviolet scanning. Wherein, the ultraviolet scanning sample is taken from the dispersion liquid at one half position below the liquid surface, and is diluted by 6 times by using stripping solvent according to the proportion of 1:5, and then the ultraviolet-visible light spectrum is scanned by taking fresh solvent as reference. Absorbance A at 660nm660The resulting concentration C0The sedimentation curve plotted against time is shown in FIG. 8. The obtained curve is expressed as C ═ C0+C1e-t/τThe parameters of the sedimentation curve obtained by fitting are shown in table 6.
TABLE 6 settling curve fitting parameters for graphene dispersions
Figure BDA0001553451100000171
C0Represents the stable dispersion concentration, i.e. the supernatant concentration after settling for an infinite time;
C1representing the initial concentration of the sediment substance, namely the concentration of the sediment substance after the sediment is settled for infinite time at the original initial moment;
τ represents the settling time constant.
As can be seen, the graphene dispersionIs stable, the settling time constant of a graphene dispersion at a concentration of about 17. mu.g/mL is 65.4h, wherein the concentration of stably dispersed graphene C0Is settleable graphene concentration C11.04 to 1.19 times of the amount of the graphene, that is, more than half of the graphene does not settle. The graphene settled during standing can be fully opened and restored by short-time ultrasound, and the temporary soft agglomeration is proved to be mainly caused by larger transverse dimension of the graphene rather than the re-stacking of the graphene into graphite.
Example 19: elemental analysis
An appropriate amount of the graphene powder obtained in example 12 was subjected to an elemental analyzer to measure the CHNS content (detection limit 0.3%) and, for comparison, elemental analysis of graphite after expansion was also performed. The results showed that the CHNS contents of the expanded graphite were 95.75 wt%, less than 0.3 wt%, undetectable, 0.83 wt%, and 0.71 wt%, respectively, while the CHNS contents of the exfoliated graphene were 91.87 wt%, 0.3 wt%, 1.33 wt%, and 1.36 wt%, respectively, and it was found that the N and H contents of the CHNS after exfoliation were slightly increased, which was converted to an aniline content of 3.32 wt%. Indicating negligible residual stripping solvent. In addition, the CHNS element weight percentages of the unexfoliated expanded graphite and the graphene are 97.59 wt% and 94.86 wt%, respectively, and if the remaining elements are all oxygen, the molar ratio of carbon element to oxygen element of the graphene is 24, which is much higher than the common reduced graphene oxide rGO although the value is lower than that of the pre-exfoliated expanded graphite (54). The obtained graphene has few defects.
Example 20: raman spectral observation
A small amount of the graphene powder prepared in example 3 was measured using a raman spectrometer, and the resulting raman spectrum was shown in fig. 9(a), in contrast to that of the non-exfoliated graphite in fig. 9 (b). Wherein, the D peak can reflect the defect information of graphene, and the G peak reflects SP2In-plane vibrational strength of hybridized carbon atoms. The ratio of the D peak intensity to the G peak intensity can reflect the defect degree of the graphene. Comparing the raman spectra of graphene and graphite in fig. 8, it can be seen that, with the G peak intensity as an internal standard, the visual representation shows that the D peak intensity of graphene is only slightly higher than that of graphite, and I thereofG/IDThe ratio is as low as 0.084, indicating that the exfoliated graphene has few defects as the original raw material graphite. Observing the graphite at 2717.8cm -12D peak of (2), which was shifted to 2701.0cm after exfoliation to graphene-1. The displacement of the 2D peak to the low wave number direction indicates that the graphene is few-layer graphene.
Example 21: SEM Observation
The graphene powder prepared in example 12 was dispersed on a silicon wafer, the silicon wafer was adhered to a conductive gel and placed under a Scanning Electron Microscope (SEM) of FEIQuanta200 in the united states for observation, and the obtained photographs at different magnifications are shown in fig. 10. It can be seen that few-layer graphene exists under the visual field, the edge of the graphene tends to be a corrugated sheet layer [ fig. 10(a) ], and the sheet layer is formed by continuously stripping, refining and collapsing graphite flakes from outside to inside, and finally a dense and rich stripped sheet layer structure is formed, so that a criss-cross corrugated porous structure form is constructed [ fig. 10(b) ]. Further enlargement of the graphene sheet layer can be seen to have a lateral dimension of up to several microns [ fig. 10(c) ], which is a graphene with a larger lateral dimension.
Example 22: TEM observation
Taking a small amount of the graphene fraction collected in example 16, dispersing in ethanol, performing ultrasonic dispersion treatment for 30min to uniformly disperse the sample, sucking a small amount of the graphene fraction with a dropper, dropping the graphene fraction on a copper net, drying in the air, and observing and photographing with a JEM-2100F high-resolution field emission electron microscope (TEM). The obtained TEM image and Selected Area Electron Diffraction (SAED) pattern of the selected area in red circle are shown in FIG. 11, FIG. 12 and FIG. 13. It can be seen that there are few layers of graphene in the obtained graphene, which can be confirmed by its nearly transparent contrast [ see fig. 11(a) and fig. 12, left figure ], and it can be known from the selected area electron diffraction of the red circle region that the selected area electron diffraction pattern shows regular hexagonal dot-like diffraction spots, indicating that the obtained graphene has a complete lattice structure. The multi-layer graphene in fig. 11(a) is a single few-layer graphene whose diffraction pattern appears as a set of regular hexagons [ fig. 11(b) ]; the multilayer graphene in the left diagram of fig. 12 is formed by stacking 2 kinds of few-layer graphene, the hexagonal diffraction pattern is dislocated, 2 sets of hexagonal diffraction spots exist [ the right diagram of fig. 12 ], and according to the brightness difference of diffraction points, the single-layer graphene is reflected by weak brightness, and the few-layer graphene is reflected by strong brightness. Further amplifying the few-layer graphene, the edge of the few-layer graphene can be seen to have a 3-layer appearance [ fig. 13, left figure ], and the few-layer graphene is known to be 3-layer graphene. In addition, the graphene sample is prepared in ethanol, and since the affinity of graphene and ethanol is lower than that of the exfoliation medium, the obtained graphene sheet is not sufficiently stretched, and some edges are curled, as shown in fig. 11(a) and fig. 12, left and fig. 13, right.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (11)

1. A preparation method of graphene is characterized in that graphite is placed in aromatic amine for sealed soaking, continuous ultrasonic treatment or multiple rounds of ultrasonic treatment for replacing fresh aromatic amine is carried out, and a product is subjected to centrifugal separation to obtain graphene;
placing graphite in aromatic amine to carry out sealed soaking, then carrying out continuous ultrasonic treatment or replacing fresh aromatic amine to carry out multi-round ultrasonic treatment, wherein the sealed soaking time is 1-60 days, and the soaking temperature is room temperature-60 daysoC;
The intercalation development induction effect of polar amino groups on aromatic amine molecules between graphite layers and aromatic rings with supplied electric amino groups increasing pi electron density are utilized to promote the conversion of the pi-pi electron effect between carbon atom layers in graphite into the effect between two pi electrons with different conjugation degrees of a carbon atom layer and an organic solvent aromatic ring, so that the cohesive energy between graphene platelets is overcome, and the graphite is finally stripped;
the obtained graphene has perfect sp2An electronic hybrid structure; the obtained stoneThe graphene has no solvent residue;
the aromatic amine is selected from one of o-toluidine, m-toluidine, p-toluidine, o-ethylaniline, m-ethylaniline, p-ethylaniline, o-propylaniline, m-propylaniline, p-propylaniline, N-methylaniline, N-ethylaniline and N-propylaniline or a binary or multicomponent blending solvent thereof.
2. The method for preparing graphene according to claim 1, wherein the ratio of the graphite to the aromatic amine is not more than 10/1 mg/mL.
3. The method according to claim 2, wherein the ratio of the graphite to the aromatic amine is 1/1 mg/mL.
4. The method for preparing graphene according to claim 1, wherein the graphite is placed in aromatic amine and sealed for 7 days.
5. The method for preparing graphene according to claim 1, wherein the temperature of ultrasonic treatment is room temperature to 60 ℃oC。
6. The method for preparing graphene according to claim 5, wherein the temperature of ultrasonic treatment is 40 degreesoC。
7. The method according to claim 1, wherein the ultrasonic frequency is 20kHz to 70 kHz.
8. The method for preparing graphene according to claim 7, wherein the ultrasonic frequency range is 53 kHz.
9. The method for preparing graphene according to claim 1, wherein the centrifugal separation mode is as follows: centrifuging the system after ultrasonic treatment, sucking and collecting supernatant to obtain graphene dispersion liquid containing graphene, wherein the conditions of centrifugal separation are as follows: centrifuging for 30-120 min at 200-1000 rpm.
10. The method according to claim 9, wherein the graphene dispersion is centrifuged, the collected graphene is washed, and then frozen and dried to remove residual aromatic amine, thereby obtaining the powdered graphene.
11. The method for preparing graphene according to claim 10, wherein the graphene dispersion is centrifuged at 7000rpm to 10000rpm for 30min to 120min, the collected graphene is washed with deionized water and ethanol, then is transferred to a cold trap of a freeze dryer for freezing for 8h, is dried for 40h, and finally is dried in a vacuum oven for 150 hoAnd C, baking for 36h to completely remove residual aromatic amine to obtain the powdered graphene.
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CN102431997A (en) * 2011-09-07 2012-05-02 南京师范大学 Graphene oxide with antibacterial and anticoagulant functions and preparation method thereof
CN102464313A (en) * 2010-11-05 2012-05-23 海洋王照明科技股份有限公司 Preparation method of graphene
CN103373724A (en) * 2012-04-17 2013-10-30 安炬科技股份有限公司 Method for preparing graphene composite material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102464313A (en) * 2010-11-05 2012-05-23 海洋王照明科技股份有限公司 Preparation method of graphene
CN102431997A (en) * 2011-09-07 2012-05-02 南京师范大学 Graphene oxide with antibacterial and anticoagulant functions and preparation method thereof
CN103373724A (en) * 2012-04-17 2013-10-30 安炬科技股份有限公司 Method for preparing graphene composite material

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Aniline- and N,N-dimethylformamide-assisted processing route for graphite nanoplates: intercalation and exfoliation pathway;Chellachamy A. Amarnath et al;《Materials Letters》;20110218;第65卷;全文 *
Changes in the electronic structure and properties of graphene induced by molecular charge-transfer;Barun Das et al;《Chemical Communication》;20080925;全文 *
原位插层聚合制备石墨烯/导电聚合物杂化结构及其电磁学性能研究;陈向南;《中国博士学位论文全文数据库·工程科技I辑》;20170415;全文 *

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