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A kind of graphene airgel natural drying preparation method

A graphene aerogel, natural drying technology, applied in the direction of graphene, nano-carbon, etc., can solve the problems of limiting the macro size, increasing the production cost and difficulty of graphene aerogel, and achieving low difficulty and low preparation cost. Effect

Active Publication Date: 2018-04-06
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, both the low-temperature vacuum conditions required for freeze-drying and the high-pressure conditions required for supercritical drying greatly increase the production cost and difficulty of graphene aerogels, and limit their macroscopic size.

Method used

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  • A kind of graphene airgel natural drying preparation method
  • A kind of graphene airgel natural drying preparation method
  • A kind of graphene airgel natural drying preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] A kind of preparation method of graphene airgel natural drying, as follows:

[0025] 1) Mix 10ml of graphene oxide solution with a concentration of 5mg / ml with 60μm reducing agent ethylenediamine (EDA) and 50μm mass fraction of 5% borax (Na 2 B 4 o 7 ) solutions, ultrasonically disperse the mixed solution for 30 minutes, take 1ml of the mixed solution in a 5ml container bottle, put the container bottle into a reaction kettle for hydrothermal reaction at 120°C for 14 hours to form a hydrogel.

[0026] 2) Dialyze the hydrogel obtained above with a volume fraction of 1% ethanol aqueous solution for 6 hours, place it in a -10°C refrigerator for 12 hours, and finally take out the frozen hydrogel under natural conditions (normal temperature and pressure) ) was dried for 24 hours to obtain graphene airgel with good shape and no large volume shrinkage. The concentration of graphene oxide solution, hydrothermal reduction time, water-alcohol ratio of dialysate and pre-freezing...

Embodiment 2

[0028] to combine figure 1 , SEM and TEM characterization tests of the internal porous structure of graphene airgel prepared by natural drying method, as follows:

[0029] The natural drying preparation method of graphene airgel proposed by the present invention is based on the reduction of capillary force produced by the natural volatilization of solvents and the bionic enhancement of the structural rigidity of the airgel itself. Due to the extrusion of ice crystal growth on the airgel structure in the pre-freezing process and the effect of liquid capillary tension in the natural drying process, the final graphene aerogel presents a unique shell-core structure, such as figure 1 as shown in a. The shell-core structure is composed of a regular honeycomb core structure in the middle and a loose shell structure around the periphery. The average pore size of the core structure is 100 microns, and the shell structure is 200 microns, such as figure 1shown in b-d. figure 1 e show...

Embodiment 3

[0031] to combine figure 2 , the mechanical property test of graphene airgel prepared by natural drying method is as follows:

[0032] The graphene airgel prepared by the natural drying method of the present invention has a recoverable compression deformation characteristic of up to 99%, and an ultimate stress of up to 1MPa, such as figure 2 As shown in a, this performance is the highest level of graphene airgel research. figure 2 b shows that the graphene airgel material has a high initial structural stiffness, which avoids volume shrinkage and structural collapse caused by capillary stress during the natural drying process. By loading the material 100 times, it is proved that the graphene airgel has stable and excellent superelastic mechanical properties, such as figure 2 c, d shown.

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Abstract

The invention provides a natural drying preparation method of graphene aerogel. The method comprises the following steps: mixing a graphene oxide solution with a reducing agent ethylenediamine (EDA) and borax, wherein hydrogel is formed by self-assembly after a period of time of hydrothermal reaction; performing dialysis and pre-freezing for a period of time for moulding; and drying to remove moisture to obtain the graphene aerogel with sound shape and without volume shrinkage. In the invention, through the improved hydrothermal reaction and a bionic means (borate crosslinking effect) between the graphene sheet layers, the rigidity of the aerogel is enhanced, the contact angle between water and graphene is controlled, and the capillary force in the drying process is remarkably reduced. In the invention, the preparation process is simple and easy to control, the production cost is low, and batch production is easy to implement; the prepared graphene aerogel has excellent mechanical property and the like; and a technical support is provided for large-scale commercial preparation of graphene aerogel.

Description

technical field [0001] The invention relates to the fields of energy and new materials, in particular to a method for preparing graphene airgel by natural drying. Background technique [0002] Graphene Aerogel is due to its excellent electrical conductivity (~10S / cm), interesting superelasticity (~99%), large specific surface area (~840m 2 / g), super high porosity (~99%), extremely low density (~10mg / cm 3 ), a series of properties such as lipophilicity and fire prevention, and has huge potential applications in the fields of energy, environmental protection, and catalyst carriers. By using graphene oxide (GO) as the precursor, through the gradual reduction of GO sheets, a large number of oxygen-containing groups on the surface are gradually detached, reducing the electrostatic repulsion between the sheets and promoting the formation of their overlapping. A stable three-dimensional overall hydrogel structure, and then the solvent in the hydrogel is removed by freeze-drying ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B32/184
CPCC01P2004/03C01P2004/04
Inventor 李惠徐翔张强强俞祎康
Owner HARBIN INST OF TECH
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