CN103408003A

CN103408003A - Method for preparing graphene

Info

Publication number: CN103408003A
Application number: CN2013103250540A
Authority: CN
Inventors: 赵伟; 韩鹏; 齐涛; 王毅; 王丽娜; 曲景奎
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2013-04-19
Filing date: 2013-07-30
Publication date: 2013-11-27
Anticipated expiration: 2033-07-30
Also published as: CN103408003B; CN103241732A

Abstract

The invention relates to a method for preparing high quality graphene in quantity. The method comprises the following technological processes: adjusting the pH value of the mixture of acidic graphite oxide and water to be 7 to 8 with 10 to 30% an ammonia water solution, gaining precipitates after centrifugation, dispersing into a small quantity of hydrazine hydrate for ultrasonic processing for hours, enabling graphite oxide to be stripped to obtain few-layer or single-layer oxidized graphene, then transferring the mixture solution into a reaction kettle, reacting for 24 to 60 hours at the temperature of 150 to 250 DEG C, filtering, water washing, and obtaining a large quantity of black products, that is, high quality graphene. The pH value of the acidic graphite oxide solution is adjusted to be neutral or slight alkaline by adopting ammonia water, not only is the wash time reduced, but also a large quantity of water is saved, and prepared graphene is not inferior to graphene prepared by the conventional method in specific surface area and specific capacitance. The method is simple and convenient to operate, low in cost and high in productivity.

Description

A kind of method for preparing Graphene

Technical field

The present invention relates to a kind of method for preparing in a large number high-quality graphene, belong to the inorganic material chemistry field.

Background technology

Graphene has just caused rapidly scientist's very big concern since from 2004, being found by Geim group, and research boom continues so far.Graphene only has monoatomic layer thickness, piles up in order by the two-dimension netted plane that carbon atom forms the crystal formed, and can be used as the elementary cell of constructing other carbon material.Simultaneously, it or a kind of zero bandgap semiconductor material.These structural performances make Graphene have a lot of excellent properties and special effects, as the quantum hall effect under: outstanding specific surface area, fabulous heat conductivity, high electron transport efficiency, Di Lake fermion, two-shipper field-effect and room temperature etc., thereby, be considered to have very tempting application prospect in fields such as biology, the energy, photoelectricity, machineries.

The preparation method of Graphene mainly contains micromechanics stripping method, epitaxy method, heating SiC method, chemical dispersion/reduction method and chemical Vapor deposition process etc. at present.At first chemical method utilizes oxidizing reaction that graphite oxidation is to graphite oxide, by graphite carbon atom between layers, introducing oxygen-containing functional group, increases interlamellar spacing, and then weakens the interaction of interlayer.Common method for oxidation has Brodie method, Staudenmaier method and Hummers method, and its principle is all first with strong acid, graphite to be processed, and then adds strong oxidizer to carry out oxidation.Graphite after oxidation forms graphene oxide by ultrasonic peeling off, and then adds reductive agent to reduce, thereby obtains Graphene.Reductive agent commonly used has hydrazine hydrate, NaBH ₄And the ultrasonic reduction of highly basic etc.NaBH ₄Because price comparison is expensive and easy residual B element, although and the ultrasonic reduction of highly basic is simple to operate and, than environmental protection, be difficult to reduction thoroughly, after reduction, usually have the residual of a large amount of oxygen-containing functional groups, thereby usually adopt more cheap hydrazine hydrate to carry out reduction-oxidation graphite.The advantage of hydrazine hydrate reduction is reducing power by force and hydrazine hydrate is easy to volatilization, can residual impurity in product, in reduction process, usually add appropriate ammoniacal liquor, improve on the one hand the reducing power of hydrazine hydrate, the surface of Graphene is repelled mutually because of electronegative, and then reduce the reunion of Graphene.

By the chemistry redox method, can realize the preparation in enormous quantities of Graphene, and the dispersiveness of intermediate product graphene oxide in water is better, is easy to realize modification and the functionalization to Graphene, so the method often is used in the researchs such as matrix material, energy storage.But because in oxidation, ultrasonic procedure in the disappearance of part carbon atom and reduction process the residual Graphene made that often makes of oxygen-containing functional group contain more defect, its electroconductibility is reduced, and then limited it in the application in the higher field of Graphene specification of quality.Wherein chemical dispersion/reduction method, because its required preparation condition is comparatively gentle and synthetic with low cost, be considered to be most appropriate to prepare in a large number the method for Graphene.That but this synthetic method also exists is time-consuming, water wasting, productive rate are low, and product Graphene surface imperfection is more, and electroconductibility has the defects such as certain loss.Therefore, chemical dispersion/reduction method will really realize prepared on a large scale by industrialized Graphene, must improve above weak point.

Summary of the invention

The present invention is directed to existing chemical dispersion/reduction and prepare the deficiency of Graphene method, propose a kind of method that ammonia scrubbing prepares high-quality graphene in a large number.

The method for preparing Graphene provided by the invention comprises the steps:

1) prepare neutral graphite oxide: in the mixture of oxytropism graphite oxide and water, drip 10%-30% ammoniacal liquor, the pH value to 7 of stirring and adjusting system～8, stirred 10～30 minutes, after standing 5-10 minute; By graphite oxide in whizzer centrifugal 5～65 minutes, outwell supernatant liquor, obtain neutral graphite oxide precipitation.

Preferably, described acidic oxidation graphite is raw material, the acidic oxidation graphite that utilizes the Hummers method to make for take crystalline flake graphite.

The oxytropism graphite oxide solution drips 10%-30% ammoniacal liquor, and the pH value to 7 of stirring and adjusting solution～8, stirred 10～30 minutes, and standing 5-10 minute, can be washed till neutrality by graphite oxide, and in this process, water and acidic oxidation graphite ratio do not exert an influence to this step; The centrifugal neutral graphite oxide precipitation that obtains of neutral graphite oxide will be washed till.

2) preparation of Graphene: the above-mentioned neutral graphite oxide precipitation made is fully mixed with hydrazine hydrate solution with the volume ratio of 1:5～5:1, after ultrasonic dispersion, under 150～250 ℃, reacted 10～60 hours, after filtration, washing, drying obtain Graphene, is stored in moisture eliminator it standby.

Preferably, the reaction times is 24～60 hours.

Preferably, the massfraction of described hydrazine hydrate solution is 85%.

Preferably, the time of ultrasonic dispersion is 30～300 minutes.

Preferably, the solution after ultrasonic dispersion is in band teflon-lined reaction kettle for reaction.

Utilize Graphene product prepared by the inventive method to have the even structure of individual layer of few layer, productive rate is higher, specific surface area and the Graphene that all prepares no less than the traditional chemical oxidation-reduction method than electric capacity.

The present invention uses the pH value of 10%-30% ammonia soln adjustment of acidity graphite oxide solution to neutrality or meta-alkalescence, not only effectively shortened the centrifugation required time, and but also saved and be washed till in a large number neutral required water, characteristic that simultaneously can also basic guarantee product Graphene, have simple to operate, with low cost, Graphene productive rate advantages of higher.And neutral graphite oxide undried processing just disperses in hydrazine hydrate solution, guaranteeing the fully decentralized while of graphite oxide, reduced the consumption of poisonous dispersion medium, have certain environment protection significance.Graphene prepared by the present invention has been applied to adsorbing the heavy metal ion such as Mercury in Industrial Waste Water, and has obtained certain effect.。

The accompanying drawing explanation

Fig. 1 is gained high-quality graphene transmission electron microscope photo of the present invention.Fig. 2 is gained high-quality graphene X-ray diffraction of the present invention (XRD) spectrogram.

Embodiment

Below by example, further describe feature of the present invention.

Embodiment 1:

Preparation process in the present embodiment is as described below:

To 50ml acidic oxidation graphite solution, carefully add while stirring 20% ammonia soln, the pH value to 8 of regulator solution, continue to stir 30 minutes standing a moment; By being washed till neutral graphite oxide solution under the rotating speed of 5000rpm centrifugal 45 minutes, outwell supernatant liquor, namely obtain a large amount of neutral graphite oxide gelatinous precipitates.The hydrazine hydrate solution that is 85% by the above-mentioned neutral graphite oxide gelatinous precipitate made and massfraction fully mixes with the volume ratio of 2:1, ultrasonic dispersion 3 hours; After being uniformly dispersed, transfer them in band teflon-lined reactor, and reaction 24 hours under 180 ℃, after filtration, washing, drying obtain the Graphene of a large amount of black, it is stored in moisture eliminator.

Acidic oxidation graphite is raw material for take crystalline flake graphite herein, the acidic oxidation graphite that utilizes the Hummers method to make, the acidic oxidation graphite in other sources also can play similar effect, those skilled in the art can select suitable acidic oxidation graphite to originate to prepare Graphene as required, no longer list herein.

Fig. 1 is gained high-quality graphene transmission electron microscope photo figure.As we know from the figure, the gained Graphene number of plies is less, be even individual layer, and size is larger, is close to clear, colorless.

Fig. 2 is gained high-quality graphene X-ray diffraction spectrogram.As seen from the figure, in 2 θ=25.6 °, located to occur the characteristic diffraction peak of Graphene (002) crystal face, interpret sample is high-quality graphene; Diffraction peaks broadening shows that the Graphene particle diameter of preparation is less.

Example 2

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Different is: the centrifugation of neutral graphite oxide solution ultrasonic jitter time in hydrazine hydrate is 2 hours, finally makes a large amount of high-quality graphenes.

Example 3

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Different is: the temperature heated in reactor is 165 ℃, and the reaction times is 60 hours, finally makes a large amount of high-quality graphenes.

Example 4

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Different is: the temperature heated in reactor is 220 ℃, and the reaction times is 10 hours, finally makes a large amount of high-quality graphenes.

Example 5

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Different is: ultrasonic jitter time is 40 minutes, and the temperature heated in reactor is 250 ℃, and the reaction times is 8 hours, finally makes a large amount of high-quality graphenes.

Claims

1. a method for preparing Graphene, comprise the steps:

1) in the mixture of oxytropism graphite oxide and water, drip 10%-30% ammoniacal liquor, the pH value to 7 of stirring and adjusting system～8, stirred 10～30 minutes, after standing 5-10 minute; By graphite oxide in whizzer centrifugal 5～65 minutes, outwell supernatant liquor, obtain neutral graphite oxide precipitation;

2) the above-mentioned neutral graphite oxide precipitation made is fully mixed with hydrazine hydrate solution with the volume ratio of 1:5～5:1, after ultrasonic dispersion, under 150～250 ℃, reacted 10～60 hours, after filtration, washing, drying obtain Graphene.

2. method according to claim 1, is characterized in that, described acidic oxidation graphite is raw material, the acidic oxidation graphite that utilizes the Hummers method to make for take crystalline flake graphite.

3. method according to claim 1, is characterized in that step 2) described in the matter of hydrazine hydrate solution

The amount mark is 85%.

4. method according to claim 1, is characterized in that step 2) in time of ultrasonic dispersion be 30～300 minutes.

5. method according to claim 1, is characterized in that step 2) in solution after ultrasonic dispersion in band teflon-lined reaction kettle for reaction.

6. method according to claim 1, is characterized in that step 2) in the reaction times be 24～60 hours.