Green preparation method for high-performance graphene

Abstract

A green preparation method for high-performance graphene, comprising the following steps: preparing graphite oxide and then preparing graphene: mixing the graphite oxide with NH4S2O8 and H2O2 under ultrasound, and then carrying out a microwave reaction to successfully prepare graphene. The method uses microwaves, which are a type of radiation heating, and can achieve penetrating heating of a bulk phase by means of microwave dielectric loss of a heated material; in addition, since an ambient medium is not heated, a high temperature of hundreds or even thousands of degrees can be reached in a very short time, causing microwave heating to have advantages such as high heating efficiency, no thermal inertia, energy saving and speed, and to be suitable for rapid heating or high-frequency, large-scale production. The prepared graphene has high quality, and due to a special stripping process, the obtained graphene has a specific surface area of ​​600-2000m2 / g and a high monolayer rate.

Description

A green preparation method for high-performance graphene Technical Field

[0001] The present invention relates to the technical field of graphene preparation, in particular to a green preparation method of high-performance graphene. Background Art

[0002] Graphene is an emerging carbon material composed of a single layer of carbon atoms arranged in an sp2 arrangement. It possesses extremely high strength, modulus, electrical conductivity, and thermal conductivity. Due to its exceptional properties, not only can graphene monomers be used in numerous fields such as electrical conductivity, energy storage, and sensing, but macroscopic graphene assemblies, such as graphene films and graphene fibers, are also widely used in daily life, electronic communications, and industrial production.

[0003] Conventional thermal reduction methods typically require heating graphite oxide to temperatures above 200°C, sometimes as high as 1000°C. This results in low production efficiency and energy utilization, as well as poor exfoliation of the graphite oxide and a low graphene monolayer ratio.

[0004] However, through experimental exploration, people have found that microwave radiation can induce molecular thermal motion of functional groups such as hydroxyl (-OH) and carboxyl (-COOH) in graphite oxide, convert electromagnetic energy into internal energy, and decompose functional groups such as hydroxyl and carboxyl groups, generating a large amount of small molecule gases (H2O, CO2) between graphite oxide sheets, overcoming the van der Waals force between graphite oxide sheets, achieving rapid exfoliation of graphite oxide sheets, and obtaining graphene.

[0005] Summary of the Invention

[0006] The object of the present invention is to provide a green preparation method for high-performance graphene to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a green preparation method for high-performance graphene, the preparation method comprising the following steps:

[0008] After preparing graphite oxide, graphene was prepared: graphite oxide was mixed with NH4S208 and H202 under ultrasound, and then subjected to microwave reaction to successfully prepare graphene.

[0009] Preferably, when preparing graphite oxide, 10 g of graphite and 230 mL of 98% concentrated sulfuric acid are mixed and placed in an ice bath, and stirred for 30 minutes to fully mix.

[0010] Preferably, preparing graphite oxide further comprises: weighing 40g KMnO4, adding the above mixture and continuing to stir for 1h, then moving into a 40°C warm water bath and continuing to stir for 30min, and diluting the reaction solution with distilled water to control the temperature below 100°C to 800-1000mL.

[0011] Preferably, the preparation of graphite oxide further comprises: adding an appropriate amount of 5% H2O2 to the diluted reaction solution, filtering it while hot, and washing it thoroughly with 5% HCl and distilled water until it is nearly neutral.

[0012] Preferably, the graphite oxide sample is obtained by filtering, washing and drying at 60°C.

[0013] Preferably, the preparation of graphene includes: weighing 0.05 g of the above-mentioned graphite oxide and adding it to 100 mL of NaOH solution with a pH of 11, and ultrasonicating at 150 W for 90 minutes to prepare a graphene oxide dispersion.

[0014] Preferably, the preparation of graphene further includes: centrifuging at 4000 r / min for 3 minutes to remove a very small amount of unexfoliated graphite oxide, adding 0.1 mL of hydrazine hydrate to the centrifuged graphene oxide dispersion, reacting at 90° C. for 2 hours to obtain a graphene dispersion, and sealing and standing for several days to observe its dispersion effect.

[0015] Preferably, when graphite oxide is mixed with NH4S208 and H202 under ultrasound and then subjected to microwave reaction, NH4S208 decomposes under microwave to produce oxygen free radicals. Under the induction of oxygen free radicals, graphite nanosheets are cut, and H202 decomposes and inserts into the interlayer of graphite nanosheets, thereby causing the exfoliation of graphene.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The green preparation method for high-performance graphene proposed in the present invention uses microwave radiation heating, which can achieve penetrating heating of the bulk phase through the dielectric loss of the heated material to the microwave. At the same time, since the ambient medium is not heated, a high temperature of hundreds or even thousands of degrees can be reached in a very short time. This makes microwave heating have the advantages of high heating efficiency, no thermal inertia, and rapid energy saving. It is suitable for rapid heating or high-frequency large-scale production. The graphene obtained is of high quality. Due to the special exfoliation process, the specific surface area of ​​the obtained graphene is 600-2000m2 / g and the monolayer rate is high. DETAILED DESCRIPTION

[0018] In order to clearly and completely describe the purpose and technical solutions of the present invention and make its advantages more clearly understood, it should be understood that the specific embodiments described herein are only part of the embodiments of the present invention, not all of them, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0019] The present invention provides a technical solution: a green preparation method for high-performance graphene, the preparation method comprising the following steps:

[0020] After preparing graphite oxide, graphene is prepared: graphite oxide is mixed with NH4S208 and H202 under ultrasound, and then subjected to microwave reaction. NH4S208 decomposes under microwave to produce oxygen free radicals. Under the induction of oxygen free radicals, graphite nanosheets are cut, and H202 decomposes and inserts into the interlayers of graphite nanosheets, thereby causing the exfoliation of graphene and successfully preparing graphene. Microwave radiation is carried out in a vacuum environment of 0.01-1000Pa. The vacuum environment can ensure that the exfoliated graphene is not oxidized during the carbonization process.

[0021] When preparing graphite oxide, 10g of graphite and 230mL of 98% concentrated sulfuric acid are mixed and placed in an ice bath, stirred for 30min to fully mix, 40g of KMnO4 is weighed and added to the above mixture, and stirring is continued for 1h, and then moved into a 40°C warm water bath and stirred for 30min. The reaction solution is diluted to 800-1000mL with distilled water at a temperature below 100°C, and an appropriate amount of 5% H2O2 is added to the diluted reaction solution, filtered while hot, and washed with 5% HCl and distilled water until it is close to neutral. Filter, wash, and dry at 60°C to obtain a graphite oxide sample; graphite oxide can also be prepared by Hummers method, improved Hummers method, Brodie method, Staudenmair method or electrochemical oxidation method;

[0022] The graphene preparation process includes: weighing 0.05 g of the above-mentioned graphite oxide and adding it to 100 mL of a NaOH solution with a pH of 11, and ultrasonicating at 150 W for 90 minutes to prepare a graphene oxide dispersion; centrifuging at 4000 r / min for 3 minutes to remove a very small amount of unexfoliated graphite oxide, adding 0.1 mL of hydrazine hydrate to the centrifuged graphene oxide dispersion, reacting at 90° C. for 2 hours to obtain a graphene dispersion, and sealing and standing for several days to observe its dispersion effect.

[0023] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A green preparation method for high-performance graphene, characterized in that: The preparation method comprises the following steps: After preparing graphite oxide, graphene was prepared: graphite oxide was mixed with NH4S208 and H202 under ultrasound, and then subjected to microwave reaction to successfully prepare graphene.

2. A green preparation method for high-performance graphene according to claim 1, characterized in that: When preparing graphite oxide, 10 g of graphite and 230 mL of 98% concentrated sulfuric acid were mixed in an ice bath and stirred for 30 minutes to fully mix.

3. A green preparation method for high-performance graphene according to claim 2, characterized in that: The preparation of graphite oxide also includes: weighing 40g KMnO4, adding it to the above mixture, continuing to stir for 1h, then moving it into a 40°C warm water bath and continuing to stir for 30min, and diluting the reaction solution to 800-1000mL with distilled water to control the temperature below 100°C.

4. The green preparation method of high-performance graphene according to claim 3, characterized in that: The preparation of graphite oxide also includes: adding an appropriate amount of 5% H2O2 to the diluted reaction solution, filtering it while hot, and washing it thoroughly with 5% HCl and distilled water until it is nearly neutral.

5. The green preparation method of high-performance graphene according to claim 4, characterized in that: The graphite oxide sample was obtained by filtering, washing and drying at 60°C.

6. The green preparation method of high-performance graphene according to claim 5, characterized in that: The preparation of graphene includes: weighing 0.05 g of the above-mentioned graphite oxide and adding it into 100 mL of NaOH solution with pH=11, and ultrasonicating at 150 W for 90 minutes to prepare a graphene oxide dispersion.

7. The green preparation method of high-performance graphene according to claim 6, characterized in that: The preparation of graphene also includes: centrifuging at 4000r / min for 3 minutes to remove a very small amount of unexfoliated graphite oxide, adding 0.1mL of hydrazine hydrate to the graphene oxide dispersion after centrifugation, reacting at 90°C for 2 hours to obtain a graphene dispersion, and sealing and standing for several days to observe its dispersion effect.

8. The green preparation method of high-performance graphene according to claim 1, characterized in that: When graphite oxide is mixed with NH4S208 and H202 under ultrasound and then subjected to microwave reaction, NH4S208 decomposes under microwave to produce oxygen free radicals. Under the induction of oxygen free radicals, graphite nanosheets are cut, and H202 decomposes and inserts into the interlayers of graphite nanosheets, resulting in the exfoliation of graphene.