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a co 2 Method for preparing graphene by exfoliating natural graphite powder by introducing dislocation slip effect in expanding liquid

A natural graphite and graphene technology, applied in the field of nanomaterials, can solve the problems of low concentration of graphene, difficult separation, and separation, and achieve the effects of simplified processing, mild reaction conditions, and simple and easy-to-control stripping process

Active Publication Date: 2017-12-19
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are still many shortcomings in the liquid phase exfoliation method, such as the use of a large amount of expensive or high boiling organic solvents, the obtained graphene concentration is very low, subsequent separation is difficult, auxiliary agents such as surfactants are difficult to separate from the product, etc.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] In a 0.1L autoclave, put 0.02LDMF, and at the same time put 0.05g natural graphite powder and 20-40 mesh quartz sand (the total volume of quartz sand is 0.01L). After sealing with CO 2 Rinse several times to discharge the air in it, preheat to the experimental temperature of 30°C, and pour CO2 through the pipeline 2 , to a pressure of 5MPa. Turn on the mechanical stirring, adjust the rotating speed to 1500rpm, and keep it for 2h. Quickly release the pressure within 2-6s after the experiment. The concentrated graphene solution is subjected to low-speed centrifugation, and the remaining solution is subjected to vacuum filtration and vacuum drying. Afterwards, by counting a large number of TEM photos, it was judged that the yield was 10%. Through AFM and Raman analysis, it is judged that single-layer graphene accounts for 30%, and the remaining 70% is less than five-layer oligolayer graphene.

Embodiment 2

[0026] In a 0.2L autoclave, put 0.04LNMP, put 0.1g of natural graphite powder and 40-80 mesh quartz sand (the total volume of quartz sand is 0.02L) at the same time, seal it with CO 2 Rinse several times to discharge the air in it, preheat to the experimental temperature of 40°C, and pour CO2 through the pipeline 2 , to a pressure of 4MPa. Turn on the mechanical stirring, adjust the rotating speed to 2000rpm, and keep it for 3h. Quickly release the pressure within 2-6s after the experiment. Reflush into CO after depressurization 2 , treated at the same temperature, pressure and rotational speed for 3h. After the pressure is released, unreacted graphite powder is removed by low-speed centrifugation, and the graphene in the solution is vacuum-filtered and vacuum-dried. By counting a large number of TEM photos, it is judged that the yield is 30%. Through AFM and Raman analysis, it is judged that single-layer graphene accounts for 50%, and the remaining 50% is less than five-...

Embodiment 3

[0028] In a 2L high-pressure reactor, put 0.4L EG, and put 10g of natural graphite powder and 40-80 mesh quartz sand at the same time (the total volume of quartz sand is 0.2L), seal it with CO 2 Rinse several times to discharge the air in it, preheat to the experimental temperature of 40°C, and pour CO2 through the pipeline 2 , to a pressure of 6MPa. Turn on the mechanical stirring, adjust the rotating speed to 3000rpm, and keep it for 5h. Quickly release the pressure within 2-6s after the experiment. The concentrated graphene solution is subjected to low-speed centrifugation, and the remaining solution is subjected to vacuum filtration and vacuum drying. After counting a large number of TEM photos, it was judged that the yield was 9%. Through AFM and Raman analysis, it is judged that single-layer graphene accounts for 25%, and the remaining 75% is less than five-layer oligolayer graphene.

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Abstract

The invention provides a method for preparing graphene by stripping natural graphite powder in a CO2 expanded liquid by introducing dislocation glide actions, belonging to the technical field of nano materials. According to the solubility-parameter-based thermodynamic calculation process, the appropriate organic solvent is selected, the system temperature, pressure and CO2 to organic solvent ratio are regulated, the physicochemical properties of the multicomponent system are regulated, and the interaction force between the graphene and organic solvent is changed, so that the surface tension of the mixed system is matched with the surface energy of the graphene. The non-normal force is introduced to generate the dislocation glide acting force, the graphite flakes can transversely slide by using the graphite self lubrication of the graphite, and the intercalation action of the small molecule CO2 is utilized to efficiently strip the graphite powder so as to prepare the graphene. By the aid of the dislocation glide action and energy conversion, the intercalation action of the CO2 small molecule is utilized, thereby enhancing the stripping efficiency. According to the method, the subsequent treatment process is simplified, and the highly-concentrated graphene dispersion solution can be obtained after the pressure relief operation.

Description

technical field [0001] The invention belongs to the technical field of nanomaterials, and provides a green, fast and efficient method for preparing graphene, and relates to a method for preparing graphene under mild conditions through CO 2 A method of directly exfoliating natural graphite powder to prepare graphene by introducing dislocation slip caused by non-orthogonal force in the expanding liquid. Background technique [0002] Graphene has become a research hotspot in the field of materials in recent years because of its unique two-dimensional crystal structure and excellent mechanical, electrical, thermal and optical properties. To realize the industrialization of graphene, the key issue is to explore large-scale, high-quality, low-cost graphene preparation technology. At present, the main preparation methods of graphene are: micromechanical exfoliation method, redox method, silicon carbide epitaxial growth method, chemical vapor deposition method, etc. The micromecha...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B32/19
CPCC01B2204/04
Inventor 银建中徐琴琴张昱
Owner DALIAN UNIV OF TECH
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