CN112500584B - Graphene/cellulose aqueous dispersion and preparation method thereof - Google Patents
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
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- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
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- C01B32/19—Preparation by exfoliation
- C01B32/192—Preparation by exfoliation starting from graphitic oxides
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- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/02—Cellulose; Modified cellulose
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- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/04—Oxycellulose; Hydrocellulose
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- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
- C08K3/042—Graphene or derivatives, e.g. graphene oxides
Abstract
The invention provides a graphene/cellulose aqueous dispersion and a preparation method thereof. According to the invention, graphite is synchronously stripped, nano-scale cellulose is prepared and hybridized in situ, so that the whole preparation process is simplified, and even the ball milling time is shortened by 12-36 hours compared with that of a common ball milling method, the yield can reach 100%, the preparation efficiency is greatly improved, the yield is improved, and the industrial mass production is realized.
Description
Technical Field
The invention belongs to the technical field of functional materials, and relates to a graphene/cellulose aqueous dispersion and a preparation method thereof.
Background
The hybrid material is a material with new performance, which is composed of two or more components at the nanometer or molecular level, is a common mode of combining various nanometer materials at present because the new performance generates an effect different from that of a single nanometer material, the graphene is an ultrathin two-dimensional carbon nanometer material, the graphene and the derivatives thereof have excellent mechanical properties, good optical properties, excellent electric conduction, heat conduction and the like, the material has been widely researched and applied in the fields of materialology, energy sources, biomedicine, drug delivery and the like, and the cellulose is one of the most popular biomass materials at present, and has the advantages of abundant reserves, wide sources, reproducibility, degradability and excellent mechanical properties.
In the prior art, two strategies exist for preparing graphene and nano-sized cellulose respectively and then carrying out hybridization or preparing nano-sized cellulose firstly and then carrying out auxiliary stripping of graphite to prepare graphene, the two strategies are too complicated and not suitable for large-scale production, meanwhile, the preparation methods of graphene, such as a chemical vapor deposition method, an epitaxial growth method and the like, have complicated preparation processes and high cost, the mechanical stripping method is simple but has low yield, the development and application of graphene are limited, the graphene oxide is easy to prepare, but the mechanical property is greatly reduced due to serious damage of a lamellar structure of the graphene oxide, and the electric conduction and heat conduction capability is basically lost, so that the graphene-based material preparation method which is synchronous to strip and in-situ hybridization, has higher yield, larger lamellar and better performance and can also be produced on a large scale is of great significance for the development and application of graphene and graphene-based hybrid materials thereof.
Disclosure of Invention
The invention aims to provide a graphene/cellulose aqueous dispersion and a preparation method thereof; aiming at the defects or improvement demands of the prior art, the method does not need to prepare graphene or nano-scale cellulose separately, the yield can reach 100%, and the obtained hybrid material has excellent performance and can realize large-scale production.
In order to achieve the above effects, the present invention provides the following technical solutions:
the preparation method of the graphene/cellulose aqueous dispersion comprises the steps of expanding a graphite sheet, then carrying out primary oxidation and secondary oxidation, regulating the pH value of a reaction system, and carrying out ball milling on mixed cellulose to obtain the graphene/cellulose aqueous dispersion.
Preferably, the method comprises the following steps:
s1, mixing and standing graphite with ammonium persulfate and 98% concentration concentrated sulfuric acid according to a certain proportion for a period of time to expand a graphite sheet;
s2, adding 98% concentrated sulfuric acid and potassium permanganate into the expanded graphite sheet to perform primary oxidation at a certain temperature;
s3, pouring the oxidized product into deionized water with the volume double that of sulfuric acid after primary oxidation, and performing secondary oxidation at a higher temperature;
s4, pouring the reaction product after secondary oxidation into a 400-mesh screen for filtering;
s5, placing the pre-oxidized graphite obtained after filtration in an alkali solution;
s6, after the pH value is regulated, mechanically grinding the mixed cellulose;
and S7, grinding to obtain graphene sheets and nano-scale cellulose hybridization material aqueous dispersion liquid.
Preferably, in the operating steps of S1-S4: the graphite is 30-100 mesh natural crystalline flake graphite, the mass ratio of ammonium persulfate to concentrated sulfuric acid to graphite is 1:2:1-10:10:1, the standing time is 2-12h, and the mass ratio of concentrated sulfuric acid to potassium permanganate to graphite is 50:0.5:1-150:1.5:1.
Preferably, in the operating steps of S1-S4: the primary oxidation reaction temperature is 30-60 ℃ and the reaction time is 4 hours, the secondary oxidation reaction temperature is 70-90 ℃ and the reaction time is 0.5-8 hours.
Preferably, in the operation step of S5: the alkali solution is sodium hydroxide solution or potassium hydroxide solution, and the pH value is adjusted to be 10-14.
Preferably, in the operation step of S6: the mechanical grinding is carried out by adopting a rotary type, vibration type, planetary ball mill, mortar or grinding tank and sand mill.
Preferably, in the operation step of S6: the mechanical grinding speed is 100-500rpm, and the grinding time is 3-36h.
Preferably, in the operation step of S6: the cellulose is microfibrillated cellulose or microcrystalline cellulose.
The graphene/cellulose aqueous dispersion prepared by the method comprises graphene sheets and nanoscale cellulose, wherein the graphene sheets exist in the dispersion in a single-layer or multi-layer mode, the thickness of the graphene sheets is 1.0-7.0nm, the size of the graphene sheets is 1-30um, the length-diameter ratio of the nanoscale cellulose is 1-200, the diameter of the nanoscale cellulose is 3-50nm, and the mass ratio of the graphene sheets to the nanoscale cellulose is 1:1-10:1.
Preferably, the nanoscale cellulose includes at least one of cellulose nanospheres, cellulose nanocrystals, and cellulose nanofibers.
The invention provides a graphene/cellulose aqueous dispersion and a preparation method thereof, and the graphene/cellulose aqueous dispersion has the following beneficial effects:
1. the graphene/cellulose hybrid material prepared by the method can be stably dispersed in a water system, is free of precipitation after standing for one month, has high concentration, can be used for preparing graphene slurry, has good conductivity and heat energy, and is wider in application range.
2. According to the invention, graphite is synchronously stripped, nano-scale cellulose is prepared and hybridized in situ, so that the whole preparation process is simplified, and even the ball milling time is shortened by 12-36 hours compared with that of a common ball milling method, the yield can reach 100%, the preparation efficiency is greatly improved, the yield is improved, and the industrial mass production is realized.
3. In the invention, a large amount of epoxy groups on the graphite oxide sheet are oxidized into carboxyl groups and hydroxyl groups by secondary oxidation, which is favorable for stripping graphene, remarkably improves the yield, can improve the hybridization degree and enhances the interaction between graphene and cellulose.
4. The yield of the invention can reach 100%, and the aqueous dispersion is alkalescent, and can be directly applied to compounding materials such as natural latex, nitrile latex and the like without the processes of centrifugation, standing and sedimentation of large particles and the like, thereby improving the industrial application efficiency.
5. The microcrystalline cellulose or microfibrillated cellulose used in the invention is ground into nano-sized cellulose, and can assist in stripping graphite to prepare graphene, the graphene can be hybridized on the graphene to prevent the graphene with extremely low oxidation degree from sedimentation after agglomeration, the nano-sized cellulose has poor dispersibility in a water system without treatment, and the nano-sized cellulose can be well dispersed in the water system through interaction of the graphene and the nano-sized cellulose.
6. Three nanoscale celluloses exist in the present invention: cellulose nanocrystals, cellulose nanofibers and cellulose nanospheres, wherein the cellulose nanospheres are prepared for the first time in a ball milling process, and nanoscale cellulose with a diameter of at least 3nm is a primary nanofiber which is difficult to prepare.
7. According to the invention, 30-100 mesh large-size natural crystalline flake graphite is adopted, compared with 325 mesh, 1000 mesh, 10000 mesh and other small-size graphite, the price is more favorable, the average size of the prepared graphene is larger, the average size is far higher than that of the graphene prepared by a conventional ball milling method, and the material conductivity, the thermal conductivity, the barrier property and the mechanical property are improved.
8. Microcrystalline cellulose or microfibrillated cellulose in the invention belongs to industrial raw materials, cellulose belongs to renewable natural polymers, and is a renewable and degradable biomass material with abundant reserves and wide sources, and is very environment-friendly.
Drawings
FIG. 1 is an AFM image of a sample according to example 1 of the present invention;
FIG. 2 is an AFM image of a sample according to example 2 of the present invention;
FIG. 3 is an AFM image of a sample according to example 3 of the present invention;
FIG. 4 is an AFM image of a sample according to example 10 of the present invention;
FIG. 5 is a graph showing a sample resistance test according to example 3 of the present invention;
FIG. 6 is a graph of ultraviolet spectra of samples and graphene oxide according to examples 1-3 of the present invention.
Detailed Description
Referring to fig. 1-6: the invention provides a technical scheme that: a graphene/cellulose aqueous dispersion comprises a dispersion liquid, wherein the dispersion liquid comprises graphene sheets and nanoscale cellulose, the graphene sheets exist in the dispersion liquid in a single-layer or multi-layer mode, the thickness of the graphene sheets is 1.0-7.0nm, the size of the graphene sheets is 1-30um, the length-diameter ratio of the nanoscale cellulose is 1-200, the diameter of the nanoscale cellulose is 3-50nm, and the mass ratio of the graphene sheets to the nanoscale cellulose is 1:1-10:1.
In particular, the nanoscale cellulose includes cellulose nanospheres, cellulose nanocrystals, and cellulose nanofibers.
A method for preparing graphene/cellulose aqueous dispersion, comprising the following steps:
firstly, mixing ammonium persulfate and 98% concentration concentrated sulfuric acid with graphite according to a certain proportion, standing for a period of time to expand a graphite sheet, wherein the graphite is 30-100 mesh natural crystalline flake graphite, the mass ratio of the ammonium persulfate to the concentrated sulfuric acid to the graphite is 1:1:1-10:10:1, and the standing time is 2-12h.
Step two, adding 98% concentration concentrated sulfuric acid and potassium permanganate to perform primary oxidation at a certain temperature after expanding the graphite sheet, wherein the mass ratio of the concentrated sulfuric acid to the potassium permanganate to the graphite is 50:0.5:1-150:1.5:1, the primary oxidation reaction temperature is 30-60 ℃, and the reaction time is 4 hours.
And thirdly, pouring the mixture into deionized water with the volume of double sulfuric acid volume after primary oxidation, and performing secondary oxidation at a higher temperature, wherein the secondary oxidation reaction temperature is 70-90 ℃, and the reaction time is 0.5-8h.
And fourthly, pouring the reaction product after the secondary oxidation into a 400-mesh screen for filtering.
And fifthly, placing the filtered preoxidized graphite in an alkali solution, wherein the alkali solution is sodium hydroxide solution or potassium hydroxide solution, and adjusting the pH value to be 10-14.
Step six, mechanically grinding the mixed cellulose after pH adjustment, wherein the mechanical grinding is performed by adopting a rotary type, vibratory type, planetary ball mill, mortar or grinding tank, and a sand mill, the mechanical grinding speed is 100-500rpm, and the grinding time is 3-36h.
And step seven, grinding to obtain graphene sheets and nano-grade cellulose hybridization material aqueous dispersion, wherein the nano-grade cellulose is cellulose nanocrystalline, cellulose nanofiber and cellulose nanospheres.
Example 1 as shown in fig. 1, there is a uniform hybridization of fine spherical and fine fibrous nano-sized cellulose on the surface of monolithic graphene.
Uniformly mixing 1g of natural crystalline flake graphite with ammonium persulfate and concentrated sulfuric acid according to the mass ratio of 1:5:5, standing for 2h, adding 50mL of concentrated sulfuric acid and 1g of potassium permanganate, stirring for 2h at normal temperature, pouring into 100mL of deionized water, heating and stirring for 30min at 80 ℃, washing the product with a screen, adding 140mL of deionized water into the product in the screen, adding sodium hydroxide solution until the pH=12 and microfibrillated cellulose are added into a ball mill according to the mass ratio of 2:1 for ball milling, and taking out after ball milling is completed at the speed of 180rpm for 24h to obtain a single-layer and multi-layer graphene and nanoscale cellulose hybridized mixed aqueous dispersion liquid with the concentration of about 1.24mg/mL and the thickness of graphene sheet layer of about 1.0-7.0nm, and standing for one month without precipitation.
Example 2 as shown in fig. 2, there is a uniform hybridization of larger spherical, elongated fibrous nanoscale cellulose on the surface of monolithic graphene.
The difference with example 1 is that the dosage of potassium permanganate is changed to 0.75g, after ball milling is completed, the single-layer and multi-layer graphene and nano-scale cellulose hybrid mixed aqueous dispersion liquid is obtained after taking out, the concentration is about 1.20mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 3, as shown in fig. 3, there is some globular, fibrous nanoscale cellulose hybridized on the surface of graphene sheets.
The difference with example 1 is that the dosage of potassium permanganate is changed to 0.5g, after ball milling is completed, the single-layer and multi-layer graphene and nano-scale cellulose hybrid mixed aqueous dispersion liquid is obtained after taking out, the concentration is about 1.12mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
As shown in fig. 5, the resistance of the hybrid material film sample is measured directly by a multimeter, and the resistance value is about 90 Ω, and the hybrid material film sample has quite excellent conductivity compared with graphene oxide.
As shown in fig. 6, the peak position of graphene oxide is 230nm, the peak position of pure graphene is 270nm, the oxidation degree is different, the peak position of ultraviolet peak is different, and the oxidation degree of graphene is lower and lower through red shift of the peak position of ultraviolet peak in examples 1-3.
Example 4, same as example 1, is different in that the dosage of potassium permanganate is changed to 1.5g, after ball milling is completed, single-layer and multi-layer graphene and nano-scale cellulose hybridized mixed aqueous dispersion liquid can be obtained, the concentration is about 1.69mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 5, same as example 1, is different in that the mass ratio of graphite to cellulose is changed to 5:1, single-layer and multi-layer graphene and nano-grade cellulose hybridized mixed aqueous dispersion liquid can be obtained after ball milling, the concentration is 1.0mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 6, same as example 1, is different in that the mass ratio of graphite to cellulose is changed to 10:1, single-layer and multi-layer graphene and nano-grade cellulose hybridized mixed aqueous dispersion liquid can be obtained after ball milling, the concentration is 0.91mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 7 is the same as example 1 except that the mass ratio of ammonium persulfate to graphite is changed to 2:1, and after ball milling is completed, single-layer and multi-layer graphene and nanoscale cellulose hybridized mixed aqueous dispersion liquid is obtained, the concentration is 1.24mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 8, same as example 1, is different in that the mass ratio of ammonium persulfate to graphite is changed to 3:1, and after ball milling is completed, single-layer and multi-layer graphene and nanoscale cellulose hybridized mixed aqueous dispersion liquid can be obtained, the concentration is 1.24mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 9, which is the same as example 1, is different in that the sodium hydroxide solution is replaced by potassium hydroxide solution, and after ball milling is completed, the single-layer and multi-layer graphene and nano-sized cellulose hybrid mixed aqueous dispersion liquid is obtained, the concentration is 1.24mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 10, as shown in fig. 4, there is a large amount of fine fibrous nano-sized cellulose hybridized on the surface of graphene.
The difference is that the microfibrillated cellulose is changed into microcrystalline cellulose, after ball milling, single-layer and multi-layer graphene and nano-grade cellulose hybridized mixed aqueous dispersion liquid can be obtained, the concentration is about 1.24mg/mL, the thickness of the graphene sheet is about 1.0-7.0nm, and no sediment exists after standing for one month.
Example 11, which is the same as example 2, is different in that microfibrillated cellulose is changed into microcrystalline cellulose, and after ball milling is completed, single-layer and multi-layer graphene and nanoscale cellulose hybridized mixed aqueous dispersion liquid can be obtained, the concentration is about 1.20mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 12, same as example 3, except that microfibrillated cellulose was changed into microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was about 1.12mg/mL, the thickness of the graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
Example 13, same as example 4, except that microfibrillated cellulose was changed to microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was about 1.29mg/mL, the thickness of the graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
Example 14, same as example 5, except that microfibrillated cellulose was changed into microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was 1.0mg/mL, the thickness of graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
Example 15, same as example 6, except that microfibrillated cellulose was changed into microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was 0.91mg/mL, the thickness of graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
Example 16, same as example 7, except that microfibrillated cellulose was changed into microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was 1.24mg/mL, the thickness of graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
Example 17, which is the same as example 8 except that microfibrillated cellulose is changed into microcrystalline cellulose, after ball milling, the mixture is taken out to obtain a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion, the concentration is 1.24mg/mL, the thickness of graphene sheets is 1.0-7.0nm, and no precipitate exists after standing for one month.
Example 18, same as example 9, except that microfibrillated cellulose was changed into microcrystalline cellulose, and after ball milling was completed, a single-layer and multi-layer graphene/nanoscale cellulose hybrid aqueous dispersion was obtained, the concentration was 1.24mg/mL, the thickness of graphene sheet was 1.0-7.0nm, and no precipitate was obtained after standing for one month.
In conclusion, the graphene/cellulose hybrid material prepared by the method can be stably dispersed in a water system, stands for one month, has no precipitation and high concentration, can be used for preparing graphene slurry, can be applied to various materials, simultaneously strips off graphite synchronously, prepares nano-sized cellulose and then carries out in-situ hybridization, simplifies the whole preparation process, shortens the ball milling time by 12-36h compared with the common ball milling method, can achieve 100% of yield, greatly improves the preparation efficiency, is more beneficial to realizing industrialized mass production, oxidizes a large amount of epoxy groups on a graphene oxide sheet into carboxyl groups and hydroxyl groups in secondary oxidation, is beneficial to stripping graphene, remarkably improves the yield, can improve the hybridization degree, enhances the interaction between graphene and cellulose, can achieve 100% of yield, is weak alkaline, does not need to be subjected to the processes of centrifugation, standing, sedimentation, and the like, can be directly applied to the compounding of materials such as natural latex, butyronitrile latex, can assist in the preparation of nano-sized cellulose, can assist the graphene stripping of microcrystalline cellulose or micro-sized cellulose into nano-sized cellulose, can realize the excellent interaction between graphene and nano-sized cellulose in the water system, can realize poor dispersion of graphene and nano-sized graphene, and the nano-sized cellulose can realize excellent interaction after the nano-sized graphene is well-dispersed in the water system, and the nano-sized graphene is well dispersed in the water system, and the nano-sized graphene is extremely poor in the nano-sized, and the graphene is extremely stable, and the graphene is easy to be dispersed, and the like, and the graphene is easy to be dispersed, and the: cellulose nanocrystals, cellulose nanofibers and cellulose nanospheres, wherein the cellulose nanospheres are prepared for the first time in a ball milling method, the diameter of nanoscale cellulose is the lowest 3nm, the cellulose nanospheres belong to primary nanofibers which are difficult to prepare, 30-100 mesh large-size natural crystalline flake graphite is adopted, compared with 325 mesh, 1000 mesh, 10000 mesh and other small-size graphite, the price is more favorable, the average size of the prepared graphene is larger, the average size is far higher than that of graphene prepared by a conventional ball milling method, the conductivity, the heat conductivity, the barrier property and the mechanical property of the material are improved, microcrystalline cellulose or microfibrillated cellulose belongs to micron-sized cellulose, independent preparation is not needed, industrial raw materials can be directly used, the cellulose belongs to renewable natural high molecules, and the renewable and degradable biomass material with abundant reserves and wide sources is very environment-friendly.
According to the invention, graphite is synchronously stripped, nano-scale cellulose is prepared and hybridized in situ, so that the whole preparation process is simplified, and even the ball milling time is shortened by 12-36 hours compared with that of a common ball milling method, the yield can reach 100%, the preparation efficiency is greatly improved, the yield is improved, and the industrial mass production is realized.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. The graphene/cellulose aqueous dispersion is characterized in that the dispersion comprises graphene sheets and nanoscale cellulose, wherein the graphene sheets exist in the dispersion in a single-layer or multi-layer mode, the thickness of the graphene sheets is 1.0-7.0nm, the size of the graphene sheets is 1-30um, the length-diameter ratio of the nanoscale cellulose is 1-200, the diameter of the nanoscale cellulose is 3-50nm, and the mass ratio of the graphene sheets to the nanoscale cellulose is 1:1-10:1; a method for preparing graphene/cellulose aqueous dispersion, comprising the following steps:
s1, mixing and standing graphite with ammonium persulfate and 98% concentration concentrated sulfuric acid according to a certain proportion for a period of time to expand a graphite sheet;
s2, adding 98% concentrated sulfuric acid and potassium permanganate into the expanded graphite sheet to perform primary oxidation at a certain temperature;
s3, pouring the oxidized product into deionized water with the volume double that of sulfuric acid after primary oxidation, and performing secondary oxidation at a higher temperature;
s4, pouring the reaction product after secondary oxidation into a 400-mesh screen for filtering;
s5, placing the filtered preoxidized graphite in an alkali solution to adjust the pH;
s6, after the pH value is regulated, mechanically grinding the mixed cellulose;
s7, grinding to obtain graphene sheets and nanoscale cellulose hybridization material aqueous dispersion;
in the operation steps of S1-S4: the graphite is 30-100 mesh natural crystalline flake graphite, the mass ratio of ammonium persulfate to concentrated sulfuric acid to graphite is 1:2:1-10:10:1, the standing time is 2-12h, and the mass ratio of concentrated sulfuric acid to potassium permanganate to graphite is 50:0.5:1-150:1.5:1; the primary oxidation reaction temperature is 30-60 ℃ and the reaction time is 4 hours, the secondary oxidation reaction temperature is 70-90 ℃ and the reaction time is 0.5-8 hours; the nanoscale cellulose comprises at least one of cellulose nanospheres, cellulose nanocrystals and cellulose nanofibers.
2. An aqueous graphene/cellulose dispersion according to claim 1, characterised in that in the operating step of S5: the alkali solution is sodium hydroxide solution or potassium hydroxide solution, and the pH value is adjusted to be 10-14.
3. An aqueous graphene/cellulose dispersion according to claim 1, characterised in that in the operating step of S6: the mechanical grinding is performed by a rotary ball mill, a vibratory ball mill, a planetary ball mill, a mortar or a sand mill.
4. An aqueous graphene/cellulose dispersion according to claim 1, characterised in that in the operating step of S6: the mechanical grinding speed is 100-500rpm, and the grinding time is 3-36h.
5. An aqueous graphene/cellulose dispersion according to claim 1, characterised in that in the operating step of S6: the cellulose is microfibrillated cellulose or microcrystalline cellulose.
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