CN106006615B - A kind of graphene aerogel spontaneously dries preparation method - Google Patents
A kind of graphene aerogel spontaneously dries preparation method Download PDFInfo
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Abstract
The present invention proposes a kind of graphene aerogel and spontaneously dries preparation method, after graphene oxide solution is mixed with reducing agent ethylenediamine EDA and borax, hydrogel is self-assembly of by hydro-thermal reaction for a period of time, it is molded for a period of time through further dialysis, pre-freeze again, finally drying removes wherein moisture to obtain the graphene aerogel of the intact no volume contraction of shape.The present invention passes through bionical means using hydro-thermal reaction is improved in graphene film interlayer --- and borate crosslinks act on, and increase aeroge stiffness by itself and control the contact angle of water and graphene that the capillary force in drying process is greatly lowered.Preparation process of the present invention is simply easily controllable, and production cost is low to be easy to produce in batches, the excellent performance such as graphene aerogel mechanics being prepared, extensive and the business of large scale prepares and provides technical support for graphene aerogel.
Description
Technical field
The present invention relates to the energy and field of new materials, and in particular to a kind of graphene aerogel spontaneously dries preparation method.
Background technology
Graphene aerogel (Graphene Aerogel) is due to its excellent electric conductivity (~10S/cm), interesting superlastic
Property (~99%), bigger serface (~840m2/ g), the porosity such as superelevation (~99%), extremely low density (~10mg/cm3),
, huge potential application in fields such as the energy, environmental protection, catalyst carriers be present in a series of performances such as oleophylic fire prevention.By using
Graphene oxide (GO) is used as presoma, by the gradual reduction to GO lamellas, makes the gradual of the substantial amounts of oxy radical in its surface
Depart from, reduce the electrostatic repulsion of piece interlayer and promote it and mutually overlap to form stable three-dimensional overall hydrogel structure, then general
Hydrogel internal solvent is removed by freeze-drying or supercritical drying and can obtain graphene three-dimensional aerogel structure.Often at present
Graphene aerogel preparation method mainly has：Assemble in situ method, induce construction from part, chemical crosslink technique.
Assemble in situ method passes through the gradual reduction to graphene oxide layer so that the substantial amounts of oxygen-containing functional group in its surface by
Gradually remove, reduce the electrostatic repulsion between lamella and promote it and mutually overlap to form stable three-dimensional overall structure.Sun Li
Great waves et al. find, when the pH value of system is 10 or so, to obtain using ammoniacal liquor and the pH value of hydrochloric acid regulation and control graphene oxide dispersion
To final product graphene aerogel there is the mechanical strength of highest electrical conductivity and highest.Qu Liangti et al. is being aoxidized
Pyrroles is introduced in the dispersion liquid of graphene as swelling agent, reduces the heap of redox graphene nanometer sheet in an assembling process
Product degree, greatly improved graphene aerogel porosity.Cheng Huiming et al. is then aided in using thiocarbamide as additive by hydro-thermal
Assemble in situ obtained high mechanical strength, pore structure and the adjustable graphene aerogel of surface chemical property, the structure pair
Some Organic Pollutants, such as dyestuff, oil product and organic solvent etc. all show extraordinary characterization of adsorption.Except utilizing
Hydro-thermal is completed outside assemble in situ, and this process can be also realized using electronation approach.For hydro-thermal approach, chemistry is also
Reason is gentle in reaction condition, it is easier to realizes prepared by extension.A series of reducing agent inductions are investigated and have prepared in Yan Li peaks et al.
The possibility of Graphene gel, result of study show NaHSO3、Na2S, a variety of inorganic, organic reduction such as HI and hydroquinones
Agent is respectively provided with the potentiality that redox graphene prepares graphene aerogel.Zhang Xuetong et al. proposes that using ascorbic acid be reduction
Agent, after redox graphene under conditions of without external disturbance is when reacting small more than 2, just it can be formed with good mechanical
The gel structure of intensity.
Construction from part is induced by the way that under the inducing action in the external world, the balance of graphene oxide colloidal dispersion system is broken,
Graphene gel structure is formed when it reaches new balance.Seo et al. is entered using traditional vacuum technological guide graphene oxide
Row assembling.In this process, the effect of centrifugal force can promote graphene oxide to be enriched with, and the evaporation of water can then make under vacuum condition
Graphene oxide forms loose structure in banking process.Pass through subsequent heat treatment, you can obtain graphene aerogel.Kim
Et al. the graphene aerogel that assembling prepares ordered big hole structure is carried out using breath pattern method induced oxidation graphene.Except water
Outside drop, ice crystal also can effective induced oxidation graphene assembling.Li et al. takes the lead in using ascorbic acid to graphene oxide
The reduction of part is carried out, in subsequent refrigerating process, the formation of ice can cause the solubility of these graphene films to reduce, from liquid
Separate out in phase, and assembled around ice crystal, obtain that there is anisotropic ordered structure；Done by follow-up
Dry and drastic reduction handles to have obtained the graphene aerogel with ordered big hole.
Chemical crosslink technique be by preparing gel in graphene oxide during further add other components in lamella
Between introduce chemical crosslinking come modulation graphene aerogel structure and property.Wang Xun et al. carries out graphene oxide and glucose
Hydro-thermal, glucose have obtained the graphene of high mechanical properties because polycondensation can form chemical crosslinking between graphene sheet layer altogether
Aerogel structure.Worsley et al. introduced in the aqueous solution of graphene oxide phenol and formaldehyde and by the use of sodium carbonate as
The polymerization of catalyst inducement phenol and formaldehyde is crosslinked together by stannic oxide/graphene nano piece；Subsequent carbonization treatment causes phenolic aldehyde
Resin is converted into carbon and crosslinking is formed between graphene sheet layer.
In summary, in graphene three-dimensional structure construction method generally existing by harshness drying preparation condition limited and
Causing at present can not large scale, large-scale production and application.Graphene aerogel is as wherein using GO as the suitable big of presoma
The graphene three-dimensional structure of scale production, because hydrogel backbone internal solvent has surface tension, it can be produced under spontaneously drying
Skeleton collapse and the contraction of volume and form xerogel, therefore all need to use Freeze Drying Technique or Supercritical Drying Technology
To remove the moisture in graphene-structured.However, either it is freeze-dried required cryogenic vacuum condition or supercritical drying
Required condition of high voltage all largely increases production cost, the difficulty of graphene aerogel of knowing clearly, and limits its macroscopical chi
It is very little.
The content of the invention
Based on above weak point, it is an object of the invention to provide a kind of graphene aerogel to spontaneously dry preparation side
Method, can possess the advantages of production cost is low, preparation difficulty is low, is set without special producing.
The technology used in the present invention method is as follows：A kind of graphene aerogel spontaneously dries preparation method, as follows：By oxygen
After graphite alkene solution mixes with reducing agent ethylenediamine EDA and borax, water-setting is self-assembly of by hydro-thermal reaction for a period of time
Glue, then be molded for a period of time through further dialysis, pre-freeze, finally drying wherein moisture will remove to obtain the intact no volume receipts of shape
The graphene aerogel of contracting.
The present invention also has following technical characteristic：
1st, graphene oxide solution concentration as described above is 5mg/ml.
2nd, the graphene oxide solution that 10ml concentration is 5mg/ml is divided with 60 μm of reducing agent ethylenediamine EDA and 50 μm of quality
Number is 5% borax Na2B4O7Solution mixes.
3rd, hydro-thermal reaction as described above is 120 DEG C of hydro-thermal reactions 14 hours.
4th, dialysis as described above uses volume fraction as 1% ethanol water.
5th, pre-freeze 12 hours in -10 DEG C are placed in as described above.
6th, a kind of graphene aerogel as described above spontaneously dries preparation method, and step is as follows：
Step 1：By the graphene oxide solution and 60 μm of reducing agent ethylenediamine EDA and 50 μm that 10ml concentration is 5mg/ml
Mass fraction is 5% borax Na2B4O7Solution mixes, and by mixed liquor ultrasonic disperse 30 minutes, takes 1ml mixed liquors in 5ml container bottles
In, container bottle is put into 120 DEG C of reactions in reactor and forms hydrogel within 14 hours；
Step 2：It is after 1% ethanol water is dialysed 6 hours, to be placed in -10 by hydrogel volume fraction obtained above
Pre-freeze 12 hours in DEG C refrigerator, finally the hydrogel after freezing is taken out and dries that to obtain shape within 24 hours intact at normal temperatures and pressures
Graphene aerogel without volume contraction.
The natural drying preparation method of graphene aerogel of the present invention, possess and prepare that cost is low, difficulty is small, without
The advantages that special installation and energy-conserving and environment-protective, alternative freeze-drying and Supercritical Drying Technology, promote graphene aerogel
On a large scale, large scale prepares and its in flexible robot, driver, sensor, electrode and ultracapacitor, ultralight protection material
Material, the application in the field such as insulation and environmental improvement.
Brief description of the drawings
Fig. 1 is to spontaneously dry graphene aerogel structure SEM, the TEM photo prepared；(a) graphite prepared is spontaneously dried
Aeroge SEM schemes；(b) graphene aerogel core space SEM schemes；(c) graphene aerogel marginal zone SEM schemes；(d) graphene gas
Gel transition region SEM schemes；(e) graphene aerogel rupture zone SEM schemes；(f) pore wall thickness SEM schemes；(g) hole wall TEM schemes (h-i)
Hole wall join domain high magnification TEM schemes；
Fig. 2 is to spontaneously dry the graphene aerogel mechanical property investigation and comparison figure prepared；(a) longitudinal direction is pressurized to reply and answered
Become 99% figure, (b) spontaneously dries preceding 5 compression chords-strain curve figure of graphene aerogel compression 50%, (c) different GO
Prepared by concentration spontaneously dries aeroge in the stress-strain curve that decrement is 99%, (d) 100 second compression circulation
Limit stress, single energy loss, Young's modulus change curve；
Fig. 3 is to spontaneously dry the graphene aerogel electricity prepared and thermal property investigation and comparison figure；(a) graphene airsetting
Glue conductivity test figure, (b) piezoresistive effect test chart, (c) Determination of conductive coefficients figure, (d) heat stability testing figure.
Embodiment
Illustrate below in conjunction with the accompanying drawings and patent of the present invention is described in more detail：
Embodiment 1：
The preparation method that a kind of graphene aerogel spontaneously dries is as follows：
1) graphene oxide solution and 60 μm of reducing agent ethylenediamines (EDA) and 50 μm of quality for being 5mg/ml by 10ml concentration
Fraction is 5% borax (Na2B4O7) solution mixing, by mixed liquor ultrasonic disperse 30 minutes, 1ml mixed liquors were taken in 5ml container bottles
In, container bottle is put into 120 DEG C of hydro-thermal reactions in reactor and forms hydrogel within 14 hours.
2) it is after 1% ethanol water is dialysed 6 hours, to be placed in -10 DEG C of ice by hydrogel volume fraction obtained above
Freezed in case 12 hours, finally the hydrogel after freezing is taken out and obtains shape within dry 24 hours under field conditions (factors) (normal temperature and pressure)
The graphene aerogel that the intact no large volume of shape is shunk.Graphene oxide solution concentration, hydrothermal reduction time, dialyzate water alcohol ratio
Volume contraction of the graphene aerogel in natural drying process and skeleton can all be collapsed with pre-freezing temperature and cause to significantly affect.
Parameter of the present invention, graphene oxide concentration is controlled in more than 4mg/ml, 14 hours hydrothermal reduction time, dialysis solution
During water alcohol volume ratio 1%, the shrinkage-free graphene aerogel of volume can be successfully prepared.Reduce hydrothermal reduction time and pre-freeze temperature
Degree, or increase dialysis solution water alcohol ratio, can cause graphene aerogel to produce different degrees of volume contraction or structure
Cave in.
Embodiment 2：
With reference to Fig. 1, natural drying method prepares inner porosity SEM, TEM characterization test of graphene aerogel, such as
Under：
Graphene aerogel proposed by the present invention spontaneously dry preparation method be based on volatilizing to solvent naturally caused by hair
The reduction of thin power and the bionical enhancing to the aeroge rigidity of structure itself.Due to during pre-freeze ice-crystal growth to aerogel structure
Extruding and natural drying process in liquid capillary tension effect so that last graphene aerogel show the shell of uniqueness-
Nuclear structure, as shown in Figure 1a.The shell-core structure is made up of the loose shell structure of the cellular nuclear structure of middle part rule and periphery.Its
Middle nuclear structure average cell size is 100 microns, and shell structure is 200 microns, as shown in Fig. 1 b-d.Fig. 1 e show peripheral shell parts
Oversized hole structure is due to caused by hole wall caused by ice-crystal growth and solvent capillary force destroys.Fig. 1 f-i show, spontaneously dry
Method, which prepares gained graphene aerogel structure, has thicker hole wall, is formed by about 70 layer graphene self assembly π-π overlap joints.
Embodiment 3：
With reference to Fig. 2, natural drying method prepares the Mechanics Performance Testing of graphene aerogel, as follows：
The present invention recovers compression using graphene aerogel prepared by natural drying method with up to 99%
Characteristic, and up to 1MPa limit stress, as shown in Figure 2 a, the performance are the highest levels of current graphene aerogel research.
Fig. 2 b show that the graphene aerogel material possesses higher initial configuration rigidity, avoid structure in natural drying process because
For the volume contraction and structure collapses caused by capillary stress.Pass through 100 CYCLIC LOADINGs to the material, it was demonstrated that the graphite
Alkene aeroge possesses stabilization, excellent super-elasticity mechanical property, as shown in Fig. 2 c, d.
Embodiment 4：
With reference to Fig. 3, natural drying method prepares the electricity of graphene aerogel, thermal property test, as follows：
Graphene aerogel prepared by natural drying method possesses up to 1.3S/cm electrical conductivity, the piezoresistive effect stablized,
Ultralow thermal conductivity factor 0.018W/mK and excellent heat endurance, as shown in Fig. 3 a-d.Above-mentioned electricity, thermal property are located
In the highest level of current graphene aerogel performance study, show that graphene aerogel proposed by the present invention spontaneously dries method
Not only prepare that cost is low, difficulty is small, and ensure that every excellent properties of aeroge, be graphene aerogel it is extensive,
Large scale prepares and provides technical support.
Claims (1)
1. a kind of graphene aerogel spontaneously dries preparation method, it is characterised in that method and step is as follows：
Step 1：By the graphene oxide solution and 60 μm of reducing agent ethylenediamine EDA and 50 μm of quality that 10ml concentration is 5mg/ml
Fraction is 5% borax Na2B4O7Solution mixes, and by mixed liquor ultrasonic disperse 30 minutes, takes 1ml mixed liquors in 5ml container bottles,
Container bottle is put into 120 DEG C of reactions in reactor and forms hydrogel within 14 hours；
Step 2：It is after 1% ethanol water is dialysed 6 hours, to be placed in -10 DEG C by hydrogel volume fraction obtained above
Pre-freeze 12 hours, finally the hydrogel after freezing is taken out and obtains within dry 24 hours at normal temperatures and pressures the intact no volume receipts of shape
The graphene aerogel of contracting；Described pre-freeze causes last graphene aerogel to show shell-core structure in 12 hours, described
Shell-core structure is made up of the loose shell structure of the cellular nuclear structure of middle part rule and periphery, and wherein nuclear structure average cell size is
100 microns, shell structure is 200 microns.
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| CN111252754B (en) * | 2020-03-12 | 2020-12-29 | 浙江大学 | Graphene aerogel air hole regulation and control method and graphene gradient aerogel |
| WO2021179232A1 (en) * | 2020-03-12 | 2021-09-16 | 浙江大学 | Method for preparing aerogel via solvent plasticization and foaming |
| CN112429721B (en) * | 2020-11-24 | 2022-03-29 | 安徽大学 | Composite graphene aerogel, preparation method and application of composite graphene aerogel in super-capacitor pressure sensor |
| CN112794705A (en) * | 2021-01-13 | 2021-05-14 | 兰州大学 | Method for preparing hyperelastic silicon oxide nano ceramic aerogel based on graphene serving as template |
| CN113441094B (en) * | 2021-05-21 | 2023-06-20 | 安徽大学 | Boron alkene-graphene composite aerogel and preparation and application thereof |
| CN115072707A (en) * | 2022-06-08 | 2022-09-20 | 哈尔滨工业大学 | Super-soft-tough multifunctional carbon aerogel and preparation method thereof |
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| CN104261392B (en) * | 2014-09-22 | 2016-08-24 | 东南大学 | A kind of preparation method of the conductive graphene paper of borate ion crosslinking |
| CN104925787B (en) * | 2015-03-19 | 2018-05-15 | 青岛科技大学 | A kind of method that constant pressure and dry prepares graphene aerogel |
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