CN103408003B

CN103408003B - Method for preparing graphene

Info

Publication number: CN103408003B
Application number: CN201310325054.0A
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: 2015-06-03
Anticipated expiration: 2033-07-30
Also published as: CN103241732A; CN103408003A

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 preparing Graphene

Technical field

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

Background technology

Since Graphene was found by Geim group from 2004, just cause rapidly the very big concern of scientist, research boom continues so far.Graphene only has monoatomic layer thickness, the crystal that the two-dimension netted plane be made up of carbon atom is piled up in order, can be used as the elementary cell of constructing other carbon material.Meanwhile, 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 etc. under outstanding specific surface area, fabulous heat conductivity, high electron transport efficiency, Di Lake fermion, two-shipper field-effect and room temperature, thus, be considered to, in fields such as biology, the energy, photoelectricity, machineries, there is very tempting application prospect.

The preparation method of current Graphene mainly contains micromechanics stripping method, epitaxy method, heating SiC method, chemical dispersion/reduction method and chemical Vapor deposition process etc.First chemical method utilizes oxidizing reaction to be graphite oxide by graphite oxidation, increases interlamellar spacing by introducing oxygen-containing functional group on graphite carbon atom between layers, 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 process graphite with strong acid, then adds strong oxidizer and is oxidized.Graphite after oxidation forms graphene oxide by ultrasonic stripping, then adds reductive agent and reduces, thus obtain Graphene.Conventional reductive agent has hydrazine hydrate, NaBH ₄and the ultrasonic reduction of highly basic etc.NaBH ₄due to the expensive and easy residual B element of price comparison, although and the simple to operate and comparatively environmental protection of the ultrasonic reduction of highly basic, be difficult to reduction thoroughly, after reduction, usually have the residual of a large amount of oxygen-containing functional group, thus usually adopt more cheap hydrazine hydrate to carry out reduction-oxidation graphite.The advantage of hydrazine hydrate reduction is that reducing power is comparatively strong and hydrazine hydrate is easy to volatilization, in the product can not residual impurity, in reduction process, usually appropriate ammoniacal liquor is added, improve the reducing power of hydrazine hydrate on the one hand, the surface of Graphene can be made mutually to repel because of electronegative on the other hand, and then reduce the reunion of Graphene.

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

Summary of the invention

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

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

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

Preferably, described acidic oxidation graphite is be raw material with crystalline flake graphite, utilizes the acidic oxidation graphite that Hummers method is obtained.

Oxytropism graphite oxide solution drips 10%-30% ammoniacal liquor, and pH value to 7 ~ 8 of stirring and adjusting solution, stir 10 ~ 30 minutes, and leave standstill 5-10 minute, graphite oxide can be washed till neutrality, in this process, water and acidic oxidation graphite ratio do not have an impact to this step; By being washed till, neutral graphite oxide is centrifugal obtains neutral graphite oxide precipitation.

2) preparation of Graphene: above-mentioned obtained neutral alumina aquadag is fully mixed with hydrazine hydrate solution with the volume ratio of 1:5 ~ 5:1, after ultrasonic disperse, react 10 ~ 60 hours at 150 ~ 250 DEG C, after filtration, washing, drying obtains Graphene, is stored in moisture eliminator for subsequent use.

Preferably, the reaction times is 24 ~ 60 hours.

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

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

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

The Graphene product utilizing the inventive method to prepare has few layer even structure of individual layer, and productive rate is higher, specific surface area and ratio capacitance be all no less than Graphene prepared by traditional chemical oxidation-reduction method.

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

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 (XRD) spectrogram of the present invention.

Embodiment

Feature of the present invention is further described below by example.

Embodiment 1:

Preparation process in the present embodiment is as described below:

Carefully add the ammonia soln of 20% while stirring to 50ml acidic oxidation graphite solution, the pH value to 8 of regulator solution, continues stirring 30 minutes, leaves standstill a moment; By being washed till neutral graphite oxide solution under the rotating speed of 5000rpm centrifugal 45 minutes, outwelling supernatant liquor, namely obtaining a large amount of neutral graphite oxide gelatinous precipitate.The hydrazine hydrate solution being 85% by above-mentioned obtained neutral alumina graphite gelatinous precipitate and massfraction fully mixes with the volume ratio of 2:1, ultrasonic disperse 3 hours; Transfer them to after being uniformly dispersed in band teflon-lined reactor, and react 24 hours at 180 DEG C, after filtration, washing, drying obtain the Graphene of a large amount of black, is stored in moisture eliminator.

Acidic oxidation graphite is take crystalline flake graphite as raw material herein, utilize the acidic oxidation graphite that Hummers method is obtained, the acidic oxidation graphite in other sources also can play similar effect, those skilled in the art can select suitable acidic oxidation graphite 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, is even individual layer, and size is comparatively large, is close to clear, colorless.

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

Example 2

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Unlike: centrifugation ultrasonic disperse time in hydrazine hydrate of neutral alumina graphite solution is 2 hours, final obtained a large amount of high-quality graphene.

Example 3

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Unlike: the temperature heated in a kettle. is 165 DEG C, and the reaction times is 60 hours, final obtained a large amount of high-quality graphene.

Example 4

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Unlike: the temperature heated in a kettle. is 220 DEG C, and the reaction times is 10 hours, final obtained a large amount of high-quality graphene.

Example 5

Preparation process in the present embodiment and step and above-mentioned example 1 are roughly the same.Unlike: the ultrasonic disperse time is 40 minutes, and the temperature heated in a kettle. is 250 DEG C, and the reaction times is 8 hours, final obtained a large amount of high-quality graphene.

Claims

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

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

2) fully mixed with hydrazine hydrate solution with the volume ratio of 1:5 ~ 5:1 by above-mentioned obtained neutral alumina aquadag, after ultrasonic disperse, react 10 ~ 60 hours at 150 ~ 250 DEG C, after filtration, washing, drying obtains Graphene;

Described acidic oxidation graphite is be raw material with crystalline flake graphite, utilizes the acidic oxidation graphite that Hummers method is obtained.

2. method according to claim 1, is characterized in that, step 2) described in the massfraction of hydrazine hydrate solution be 85%.

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

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

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