CN105645385B - A method of preparing graphene - Google Patents
A method of preparing graphene Download PDFInfo
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- CN105645385B CN105645385B CN201410723515.4A CN201410723515A CN105645385B CN 105645385 B CN105645385 B CN 105645385B CN 201410723515 A CN201410723515 A CN 201410723515A CN 105645385 B CN105645385 B CN 105645385B
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Abstract
The invention discloses it is a kind of based on flocculation-solution flocculation realize graphite oxide it is quick, efficiently separate, then the method that graphene is prepared by reduction reaction.This method includes three steps: the 1. oxidation reaction of graphite obtains the mixed liquor containing graphite oxide, inorganic salts and acid；2. flocculation is conciliate in the flocculation of graphite oxide, evenly dispersed graphite oxide dispersion is obtained；3. reduction reaction, obtain can fine dispersion graphene.In the present invention, controlled flocculation agent realize graphite oxide separation, adjusting control agent realize graphite oxide solution flocculation and it is evenly dispersed, and reduction when graphite oxide controlled flocculation agent have stablizing effect to graphene；Three steps are all linked with one another, and the two large problems of the separation of graphite oxide difficulty and the dispersion of graphene difficulty that disposably solve are, it can be achieved that efficient, prepare with scale high dispersive graphene.
Description
Technical field
The invention belongs to technical field of graphene, and in particular to a method of efficiently prepare graphene.
Background technique
Graphene is a kind of novel two-dimensional nano-carbon material, due to excellent electricity, calorifics, optically and mechanically property
Can, it is expected to be widely used in fields such as battery material, energy storage material, electronic device, composite materials.Wherein, graphene
Prepare with scale, where cost effective and dispersion is its widely applied key technology.
Currently, graphene preparation method mainly has a micromechanics stripping method, crystal epitaxy method, chemical vapour deposition technique and
Oxidation-reduction method etc..First three methods because complicated for operation, condition is harsh, low yield and it is at high cost etc. limit the preparation of its scale and
Applications in various fields；And oxidation-reduction method is using graphite cheap and easy to get as raw material, can be mass with chemically reactive modification, recognized
To be graphene prepare with scale and being easy to the main stream approach of practical application.Oxidation-reduction method mainly passes through strong oxidizer in liquid
Graphite oxide/graphene oxide (i.e. oxidation stage) is prepared after aoxidizing in phase to crystalline flake graphite, later by reduction
Obtain graphene (i.e. reduction phase).Wherein, quick chemical oxidation reaction and efficient separation are oxidation stage keys, and high
The reduction reaction of effect and surface treatment are the key that reduction phases.
For oxidation stage, prepare graphite oxide/graphene oxide chemical oxidation reaction (such as classical Hummers method)
Having used the strong oxidizers such as strong acid, potassium permanganate such as including the concentrated sulfuric acid is raw material.It is removed in liquid after the completion of chemical oxidation reaction
Outside target product, also containing by-products and unreacted residual acid such as a large amount of inorganic salts.Due to graphite oxide with " hydroxyl ",
A variety of oxygen-containing groups such as " epoxy ", " carbonyl ", " carboxylic acid ", have good hydrophily, in water dispersibility and film forming all
Very well.It is difficult to using common filtering, suction filtration, centrifugation etc. by graphite oxide/graphene oxide separation, purifying, in the scale of progress
Change preparation when inefficiency, time-consuming, cost is also higher.Therefore, graphite oxide/graphene oxide is efficient, scale separation
It is problem to be solved in graphene heavy industrialization application process.
For reduction phase, existing reduction technique is mainly carried out thermal reduction at high temperature with solid phase and passed through in the liquid phase
Reducing agent is restored to obtain graphene.United States Patent (USP) US 7658901 is using 1050 DEG C of high temperature to oxidation graphite solid powder
End has carried out thermal reduction and graphene is prepared；Ruoff etc. using hydrazine hydrate as reducing agent by graphite oxide in aqueous dispersions into
Graphene (Ruoff, et al.Carbon, 2007,45,1558) is prepared in row liquid-phase reduction.Have during high temperature thermal reduction
It has been removed conducive to the organo-functional group or molecule of graphene dispersion, resulting graphene is easy to reunite, in a solvent bad dispersibility.
The resulting graphene of reducing agent liquid-phase reduction causes to reunite since lamella is inclined to returning again folded, dispersed in a solvent
Difference.Therefore, the dispersibility of graphene is also problem to be solved during large-scale application.The high temperature thermal reduction of solid phase has no
Dispersion problem is solved, and the method restored in liquid phase can be can be obtained by the way that surface treating agent is added in reduction reaction process
The well dispersed graphene of energy in solvent.Stankovich etc. is table by reducing agent, addition kayexalate of hydrazine hydrate
Surface treatment agent, obtained graphene can be stably dispersed in water (Stankovich, et al.Journal of Material
Chemistry,2006,16,155)。
In the prior art, Chinese patent (application number: 200910062869.8) discloses graphite oxide is soluble in water, super
Sound is removed to obtain the aqueous solution of graphene oxide, then obtains single-layer graphene oxide on a large scale by flocculating setting and drying.
What the patent obtained is the solid aggregate of single-layer graphene oxide, it is difficult to it is dispersed again in solvent, it can not be by liquid phase also
Original is changed into graphene, to hinder its application；More importantly the patent, which is built upon, has obtained a large amount of graphite oxides
On the basis of (mixed liquor for obtaining graphite after aoxidizing filtered, it is neutral to be washed till, is dried to obtain graphite oxide), and it is direct
By being filtered to mixed liquor, by graphite oxide from the aqueous solution containing impurity separate itself is a low efficiency,
The process that time-consuming especially filters after the second half section forms colloid extremely difficult.Chinese patent (application number:
201110056093.6) it discloses to efficiently separate out graphite oxide flocculating setting by addition organic flocculant and aoxidizes stone
Ink, then the oxidation graphite solid through being dried to obtain is obtained into graphene powder by high temperature reduction.Although the patent passes through flocculation
Sedimentation is able to achieve efficiently separating for graphite oxide, but its by graphite oxide flocculating setting and isolated product is still reunion
Object can not be also dispersed again in solvent, also can not be changed into graphene by liquid-phase reduction.The patent is selected by drying
Obtained oxidation graphite solid carries out high temperature reduction to which graphene can be obtained, but since the overwhelming majority is conducive to graphene dispersion
Organo-functional group and the organic flocculant that uses be removed in the high temperature process, resulting graphene is easy to reunite, in solvent
Middle bad dispersibility.Therefore this method also fails to be fully solved the problems in graphene heavy industrialization application process.
Summary of the invention
The purpose of the present invention is being directed to the industrialized the problems of the prior art of graphene, oxidation-reduction method is disposably solved
Middle graphite oxide efficiently separates the two big difficulties with graphene dispersion, provides one kind and efficiently prepares polymolecularity graphene
Method.
The purpose of the present invention can be achieved by the following measures:
A kind of preparation method of graphene, includes the following steps: the oxidation reaction of 1. graphite；2. the flocculation of graphite oxide and
Solution flocculation；3. reduction reaction.
Step 1. in the oxidation reaction of graphite be to carry out oxygen with the mixed liquor of strong oxidizer and strong acid using graphite as raw material
Change, obtains the mixed liquor containing graphite oxide, inorganic salts and acid.
The strong oxidizer is one or more of potassium permanganate, potassium chlorate, sodium chlorate or potassium bichromate；Strong acid is
One or both of the concentrated sulfuric acid or concentrated nitric acid.
Step 1. in graphite oxidation reaction advantageous embodiment Hummers method.Concrete example is as follows: the concentrated sulfuric acid, sodium nitrate,
Potassium permanganate is added in graphite powder as raw material, is reacted while stirring, 25-50 DEG C reaction 0.2-5 hours.Hereafter, it is added
Deionized water dilutes to obtain suspension, 80-100 DEG C reaction 5-50 minutes.Finally, hydrogen peroxide and deionized water reaction 1- is added
After 30 minutes, the mixed liquor containing graphite oxide, inorganic salts and acid is obtained.
For example, in Hummers method, the ratio of each reactive material is more preferably, i.e., graphite, the concentrated sulfuric acid, sodium nitrate,
Potassium permanganate, hydrogen peroxide ratio be 10g:(150-300) ml:(2-8) g:(10-40) g:(40-80) g.
, it is preferable to use ice bath when strong oxidizer and strong acid is added.
Hydrogen peroxide is added and deionized water, the quality of deionized water are preferably 10-20 times of hydrogen peroxide.
The mass content of the concentrated sulfuric acid used in the present invention is preferably not less than 70%.The concentrated sulfuric acid is further preferably not less than
97%.
The preferred graphite powder of the graphite, further preferably crystalline graphite powder, still more preferably natural flake graphite
Powder.The mesh number of graphite powder is preferably 500 mesh~20000 mesh, it is contemplated that effect and cost be more preferably 1500 mesh~
12000 mesh.
The oxidizability of graphite oxide can be adjusted by changing the amount of the oxidant in graphite oxidation reaction.It is specific and
Speech, big using the amount of potassium permanganate in the oxidation reaction for a certain amount of graphite, then oxidizability is high；It is on the contrary then low.Oxidizability
It can be measured by the molar ratio of oxygen atom in graphite oxide and carbon atom.In view of the oxidation removing of graphite and gained aoxidize
The dispersion of graphite passes through the molar ratio preferably 0.45 or more of the XPS oxygen atom measured and carbon atom, it is contemplated that reduction obtains
Graphene conductive, by the molar ratio preferably 0.55 of the XPS oxygen atom measured and carbon atom and following.
Step 2. in graphite oxide flocculation reconciliation flocculate be directed in the mixed liquor containing graphite oxide, inorganic salts and acid
Controlled flocculation inorganic agent is added, is separated after making graphite oxide flocculating setting；Isolated flocculation state graphite oxide adds in water
Enter adjusting control agent deflocculation, finely dispersed graphite oxide dispersion is prepared.
It is direct that mode of operation can be the mixed liquor containing graphite oxide, inorganic salts and acid obtained after aoxidizing to graphite
Controlled flocculation inorganic agent is added and carries out flocculating setting；Suction filtration removal part nothing can also be first passed through before graphite oxide forms colloid
Machine salt and acid (the suction filtration operation before colloid is formed is not difficult, and colloid formed after suction filtration is extremely difficult, efficiency is extremely low), then it is right
The mixed liquor containing graphite oxide, inorganic salts and acid of removal part inorganic salts and acid is added controlled flocculation inorganic agent and flocculates
Sedimentation.
Controlled flocculation inorganic agent refers to a kind of inorganic agent that the flocculation reconciliation flocculation that can make graphite oxide is controllable, that is, is added
Graphite oxide can flocculate after the inorganic agent, and then (such as: pH value variation, ion are strong for response under the stimulation of change of external conditions
Spend variation, temperature change, separately add adjusting control agent), realize flocculated releasing.
The controlled flocculation inorganic agent preferably organic matter containing aryl and quaternary ammonium group simultaneously.Graphite oxide is that have squama
For piece graphite through oxidation gained, structure is that " hydroxyl ", " epoxy ", " carbonyl " or " carboxylic are introduced in the big conjugate planes of script
A variety of oxygen-containing groups such as acid ".Controlled flocculation inorganic agent of the invention due to preferably simultaneously contain aryl and quaternary ammonium group, aryl
Phenyl ring can have pi-pi effect with conjugate moiety on graphite oxide, and quaternary ammonium group can have electricity with the oxygen-containing group on graphite oxide
Lotus interaction, to have good flocculating effect to graphite oxide.In view of the dissolution of controlled flocculation inorganic agent in water
Property, the controlled flocculation inorganic agent preferably small organic molecule containing aryl and quaternary ammonium group simultaneously.In view of effect, at controlled flocculation
Aryl and quaternary ammonium group in reason agent are preferred the two of small organic molecule ends respectively, preferably the aryl at molecule both ends and season
The short alkyl chain of 5 carbon, most preferably benzyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzene are no more than among ammonium group
One or more of base trimethylammonium bromide or phenyl trimethicone ammonium chloride.
Controlled flocculation inorganic agent is to the Flocculation Mechanism of graphite oxide and the Flocculation Mechanism of common organic flocculant
It is different.For example, the aliphatic cationic flocculant such as " cetyl ammonium bromide ", does not have pi-pi effect with graphite oxide, is
The charge interaction of the oxygen-containing groups such as " carboxylic acid " in cationic " quaternary ammonium group " and graphite oxide, while flocculant can be passed through
Cladding/bridge formation of longer alkyl chain etc. is by graphite oxide flocculating setting, but isolated graphite oxide flocculate can not pass through
Outside stimulus realizes flocculated releasing.And the controlled flocculation inorganic agent in the present invention passes through the dual interaction with graphite oxide
Realize flocculation, i.e. there are two " anchor points " for a controlled flocculation processing agent molecule, realize without the cladding etc. by strand
Flocculation.Therefore, graphite oxide flocculating setting, isolated flocculation state are aoxidized using the controlled flocculation inorganic agent in the present invention
Flocculated releasing can be achieved by outside stimulus (as used adjusting control agent) in graphite, and the oxidation stone of uniform dispersion can be prepared later
Black dispersion liquid/graphene oxide dispersion (graphene oxide dispersion can be obtained after the removing of graphite oxide dispersion ultrasound).
The adjusting control agent is alkaline solution, preferably one of ammonium hydroxide, sodium hydrate aqueous solution or potassium hydroxide aqueous solution
Or it is several.In view of the graphene being prepared later is avoided containing unnecessary substance, most preferably adjusting control agent is ammonium hydroxide.It is added
" quaternary ammonium group " and " carboxyl " on graphite oxide of controlled flocculation inorganic agent etc. can be eliminated or be weakened to a small amount of alkaline solution
The charge or hydrogen bond action of oxygen-containing group, so that a controlled flocculation handles the only one " anchoring of agent molecule and graphite oxide
" anchor point " of point ", i.e. pi-pi effect, also forms without networks such as claddings.Therefore, isolated flocculation state graphite oxide
Yu Shuizhong be added adjusting control agent can deflocculation, be prepared the graphite oxide dispersion of uniform dispersion, graphite oxide dispersion is super
Graphene oxide dispersion can be obtained after sound removing.
Step 3. in reduction reaction be not particularly limited.In view of the dispersibility for the graphene being prepared, preferably exist
It is restored under liquid-phase system using reducing agent.As described above, after deflocculation, the aryl phenyl ring and graphite oxide of agent molecule are handled
Conjugate moiety still pi-pi is kept to act on, reduction is carried out in the liquid-phase systems such as water when graphene is prepared, passes through pi-
The processing agent molecule of pi effect " anchoring " on the surface of graphene is conducive to the dispersion of graphene, when avoiding solid high-temperature thermal reduction
The organic molecule that the overwhelming majority is conducive to graphene dispersion removes in the high temperature process.
In view of electric conductivity and reduction efficiency, preferably high-efficiency reducing agent such as sodium dithionite, potassium hyposulfite or
One or more of hydrazine hydrate.In view of low cost, liquid-phase system is preferably aqueous systems.The graphite oxide water that will be prepared
Dispersion liquid after sonication, is added reducing agent and is reacted, and after the reaction was completed, filtering, washing and dry can be obtained can be molten
The graphene powder of stable dispersion in agent.
Graphene preparation method in the present invention is can be realized fast and efficiently using the flocculated method of flocculation-solution by oxygen
Graphite is separated, and the graphite oxide that can be realized the solution flocculation of flocculation state graphite oxide and uniform dispersion is prepared divides
Dispersion liquid；The graphite oxide flocculation treatment agent added originally after solution flocculation plays stabilization in reduction, can be prepared good
The graphene dispersed well.The method of the present invention is all linked with one another, disposably solves graphite oxide separation in the prior art and graphene
The two large problems of dispersion provide a kind of efficient, prepare with scale high dispersive, the method for highly conductive graphene.Side of the present invention
The graphene that method is prepared can be used for high-performance conductive/heat-conductive composite material, energy storage material, electronic device, functional coating etc.
Field.
Detailed description of the invention
Fig. 1 is flocculation state graphite oxide Yu Shuizhong isolated in the embodiment of the present invention 1 before adjusting control agent is added
Photo.
Fig. 2 is flocculation state graphite oxide Yu Shuizhong isolated in the embodiment of the present invention 1 after adjusting control agent is added
Photo.
Compare Fig. 1 and Fig. 2 it is found that the obtained graphite oxide flocculate Yu Shuizhong of controlled flocculation agent is after being added adjusting control agent
Solution flocculation completely, obtains the graphite oxide aqueous dispersions of uniform dispersion.
Fig. 3 is flocculation state graphite oxide Yu Shuizhong isolated in comparative example 1 of the present invention before adjusting control agent is added
Photo.
Fig. 4 is flocculation state graphite oxide Yu Shuizhong isolated in comparative example 1 of the present invention after adjusting control agent is added
Photo.
Compare Fig. 3 and Fig. 4 it is found that the graphite oxide flocculate that common flocculant obtains cannot disperse in water, and add
Flocculation can not be solved later by entering adjusting control agent.
Specific embodiment
Specific chemicals involved in the present invention:
Natural graphite powder is purchased from one sail graphite Co., Ltd of Shanghai；
The concentrated sulfuric acid, sodium nitrate, potassium permanganate, hydrogen peroxide, sodium dithionite, potassium hyposulfite, hydrazine hydrate, benzyl
Trimethylammonium bromide, benzyltrimethylammonium chloride, phenyltrimethylammonium bromide, phenyl trimethicone ammonium chloride, cetyl bromination
Ammonium, ammonium hydroxide, N-Methyl pyrrolidone etc. are purchased from Chinese Chinese medicines group Reagent Company or Aladdin Reagent Company.
The test of graphite oxide oxidizability:
The oxidizability of graphite oxide can be measured by the molar ratio of oxygen atom in graphite oxide and carbon atom.Aoxidize stone
Black mixed liquor is sufficiently cleaned, obtains graphite oxide powder after freeze-drying, is tested by x-ray photoelectron spectroscopy (XPS)
To the molar ratio of oxygen atom and carbon atom.The XPS spectrum of each sample be using Quantera SXM (ULVAC-PHI company) into
Row is tested and is obtained.Exciting X-ray is monochromatic Al Kα1,2Ray (1486.6eV), X-ray diameter are 200 microns, photoelectron
Exit angle (take-off angle) is 45 °.
The test of graphene dispersion:
Dispersion performance is tested as follows.By Graphene powder obtained in 1 part of following embodiments or comparative example
End and 99 parts of N-Methyl pyrrolidones are added in sample bottle, after handling 30 minutes in ultrasonic cleaner, observe settling phase.
If solution is in the state of visual homogeneity, it can determine whether that it is in the state of good dispersion；If become at the top of solution
Clearly, or when sediment is observed in solution bottom, then it can determine whether that it is in the state of layering.
Embodiment 1
(1) oxidation reaction of graphite: with 15g natural graphite powder (1500 mesh) for raw material, it is added 330ml's in ice bath
98% concentrated sulfuric acid, 7.5g sodium nitrate and 45g potassium permanganate keep mixeding liquid temperature to be lower than 20 DEG C, mechanical stirring 1.5 hours.It will
Above-mentioned mixed liquor takes out from ice bath, and stirred in water bath 2.5 hours at 35 DEG C are reacted.690ml deionization is added later
Water obtains suspension, further reacts 15 minutes at 90 DEG C.It is eventually adding 1020ml deionized water and 50ml hydrogen peroxide, is reacted
5 minutes to get the mixed liquor containing graphite oxide, inorganic salts and acid for arriving yellow.Wherein, the oxygen atom of graphite oxide and carbon are former
The ratio of son is 0.53 by XPS test.
(2) separation and dispersion of graphite oxide are realized in flocculation reconciliation flocculation: that states directly up contains graphite oxide, inorganic
Controlled flocculation inorganic agent benzyltrimethylammonium chloride is added in the mixed liquor of salt and acid, and (flocculation treatment agent is in the concentration of system
2.5g/L), it after settling graphite oxide rapid flocculation, pours out supernatant liquor and obtains sediment, washing, suction filtration obtain flocculation state oxygen
Graphite filter cake；Isolated flocculation state graphite oxide filter cake is diluted with water to 0.5wt% again, is added adjusting control agent " ammonium hydroxide "
So that system pH be greater than 7, stirring can deflocculation, the graphite oxide aqueous dispersions of uniform dispersion are made.
(3) reduction reaction: the graphite oxide aqueous dispersions (concentration 0.5wt%) of above-mentioned uniform dispersion are through ultrasonication
Afterwards, the aqueous dispersions of evenly dispersed khaki graphene oxide are obtained.Add in the aqueous dispersions of the graphene oxide of 200ml
Enter 3 grams of reducing agent sodium dithionites and carries out reduction reaction.Reduction reaction temperature is 40 DEG C, and the reduction reaction time is 30 minutes.
It is filtered, washes, obtain graphene powder after freeze-drying.
The dispersion performance of graphene powder is tested using the method for test case.Still steadily divide after 10 days
It dissipates, does not observe sedimentation.
Embodiment 2
(1) oxidation reaction of graphite: with 15g natural graphite powder (12000 mesh) for raw material, it is added 330ml's in ice bath
98% concentrated sulfuric acid, 5.25g sodium nitrate and 31.5g potassium permanganate keep mixeding liquid temperature to be lower than 20 DEG C, mechanical stirring 1.5 hours.
Above-mentioned mixed liquor is taken out from ice bath, stirred in water bath 2.5 hours at 35 DEG C are reacted.Later be added 690ml go from
Sub- water obtains suspension, further reacts 15 minutes at 90 DEG C.It is eventually adding 1020ml deionized water and 50ml hydrogen peroxide, instead
Answer 5 minutes to get arrive yellow the mixed liquor containing graphite oxide, inorganic salts and acid.Wherein, the oxygen atom and carbon of graphite oxide
The ratio of atom is 0.45 by XPS test.
(2) separation and dispersion of graphite oxide are realized in flocculation reconciliation flocculation: that states directly up contains graphite oxide, inorganic
Controlled flocculation inorganic agent benzyltrimethylammonium bromide is added in the mixed liquor of salt and acid, and (flocculation treatment agent is in the concentration of system
2g/L), it after settling graphite oxide rapid flocculation, pours out supernatant liquor and obtains sediment, washing filters the state oxidation that obtains flocculating
Graphite Cake；Isolated flocculation state graphite oxide filter cake is diluted with water to 0.5wt% again, adjusting control agent " ammonium hydroxide ", which is added, to be made
System pH be greater than 7, stirring can deflocculation, the graphite oxide aqueous dispersions of uniform dispersion are made.
(3) reduction reaction: the graphite oxide aqueous dispersions (concentration 0.5wt%) of above-mentioned uniform dispersion are through ultrasonication
Afterwards, the aqueous dispersions of evenly dispersed khaki graphene oxide are obtained.Add in the aqueous dispersions of the graphene oxide of 200ml
Enter 3 grams of reducing agent potassium hyposulfites and carries out reduction reaction.Reduction reaction temperature is 40 DEG C, and the reduction reaction time is 30 minutes.
It is filtered, washes, obtain graphene powder after freeze-drying.
The dispersion performance of graphene powder is tested using the method for test case.Still steadily divide after 10 days
It dissipates, does not observe sedimentation.
Embodiment 3
(1) oxidation reaction of graphite: with the step (1) in embodiment 1.
(2) flocculation reconciliation flocculation realize graphite oxide separation and dispersion: obtained in step (1) containing graphite oxide,
The mixed liquor of inorganic salts and acid, which first passes through, filters removal part inorganic salts and acid, before forming colloid, occurring filtering difficulty, then
Controlled flocculation inorganic agent benzyl trimethyl is added to the mixed liquor (concentration) containing graphite oxide of removal part inorganic salts and acid
Ammonium chloride (flocculation treatment agent is 1g/L in the concentration of system), after settling graphite oxide rapid flocculation, pours out supernatant liquor and obtains
To sediment, washing, suction filtration obtain flocculation state graphite oxide filter cake；Again by isolated flocculation state graphite oxide filter cake water
Be diluted to 0.5wt%, be added adjusting control agent " ammonium hydroxide " make system pH be greater than 7, stirring can deflocculation, uniform dispersion is made
Graphite oxide aqueous dispersions.
(3) reduction reaction: the graphite oxide aqueous dispersions (concentration 0.5wt%) of above-mentioned uniform dispersion are through ultrasonication
Afterwards, the aqueous dispersions of evenly dispersed khaki graphene oxide are obtained.Add in the aqueous dispersions of the graphene oxide of 200ml
Enter 3 grams of reducing agent sodium dithionites and carries out reduction reaction.Reduction reaction temperature is 40 DEG C, and the reduction reaction time is 30 minutes.
It is filtered, washes, obtain graphene powder after freeze-drying.
The dispersion performance of graphene powder is tested using the method for test case.Still steadily divide after 10 days
It dissipates, does not observe sedimentation.
Embodiment 4
(1) oxidation reaction of graphite: with the step (1) in embodiment 2.
(2) flocculation reconciliation flocculation realize graphite oxide separation and dispersion: obtained in step (1) containing graphite oxide,
The mixed liquor of inorganic salts and acid, which first passes through, filters removal part inorganic salts and acid, before forming colloid, occurring filtering difficulty, then
Controlled flocculation inorganic agent phenyl trimethicone is added to the mixed liquor (concentration) containing graphite oxide of removal part inorganic salts and acid
Ammonium bromide (flocculation treatment agent is 1g/L in the concentration of system), after settling graphite oxide rapid flocculation, pours out supernatant liquor and obtains
To sediment, washing, suction filtration obtain flocculation state graphite oxide filter cake；Again by isolated flocculation state graphite oxide filter cake water
Be diluted to 0.5wt%, be added adjusting control agent " ammonium hydroxide " make system pH be greater than 7, stirring can deflocculation, uniform dispersion is made
Graphite oxide aqueous dispersions.
(3) reduction reaction: the graphite oxide aqueous dispersions (concentration 0.5wt%) of above-mentioned uniform dispersion are through ultrasonication
Afterwards, the aqueous dispersions of evenly dispersed khaki graphene oxide are obtained.Add in the aqueous dispersions of the graphene oxide of 200ml
Enter 3 grams of reducing agent hydrazine hydrates and carries out reduction reaction.Reduction reaction temperature is 100 DEG C, and the reduction reaction time is 24 hours.By
Filter, washing, obtains graphene powder after freeze-drying.
The dispersion performance of graphene powder is tested using the method for test case.Still steadily divide after 10 days
It dissipates, does not observe sedimentation.
Embodiment 5
(1) oxidation reaction of graphite: with 15g natural graphite powder (12000 mesh) for raw material, it is added 330ml's in ice bath
98% concentrated sulfuric acid, 4.1g sodium nitrate and 24.8g potassium permanganate keep mixeding liquid temperature to be lower than 20 DEG C, mechanical stirring 1.5 hours.
Above-mentioned mixed liquor is taken out from ice bath, stirred in water bath 2.5 hours at 35 DEG C are reacted.Later be added 690ml go from
Sub- water obtains suspension, further reacts 15 minutes at 90 DEG C.It is eventually adding 1020ml deionized water and 50ml hydrogen peroxide, instead
Answer 5 minutes to get arrive yellow the mixed liquor containing graphite oxide, inorganic salts and acid.Wherein, the oxygen atom and carbon of graphite oxide
The ratio of atom is 0.4 by XPS test.
(2) separation and dispersion of graphite oxide are realized in flocculation reconciliation flocculation: with the step (2) in embodiment 2.
(3) reduction reaction: with the step (3) in embodiment 2.
The dispersion performance of graphene powder is tested using the method for test case.Still steadily divide after 3 days
It dissipates, does not observe sedimentation；Sedimentation is observed after 10 days.
Comparative example 1
(1) oxidation reaction of graphite: with the step (1) in embodiment 1.
(2) flocculant hexadecane bromide is added in the mixed liquor containing graphite oxide, inorganic salts and acid stated directly up
Change ammonium (flocculant is 2.5g/L in the concentration of system), after settling graphite oxide rapid flocculation, pours out supernatant liquor and sunk
Object drops, and washing, suction filtration obtain flocculation state graphite oxide filter cake；Isolated flocculation state graphite oxide filter cake is diluted with water again
To 0.5wt%, the graphite oxide for state of flocculating uniform can not disperse；Adjusting control agent " ammonium hydroxide " is added later makes system pH be greater than 7,
Flocculate state graphite oxide can not deflocculation, the graphite oxide aqueous dispersions of uniform dispersion can not be prepared.
(3) reduction reaction: due to the flocculation state graphite oxide can not redisperse, can not deflocculation, therefore, it is impossible to
Graphene is prepared by the reduction reaction under liquid-phase system.
Graphene is prepared by high temperature thermal reduction: obtained flocculation state graphite oxide filter cake will be filtered in step (2) 60
DEG C drying, be placed on the drying of 1000 DEG C of Muffle furnaces thermal reduction 15 seconds, make graphite oxide expansion removing, oxygen-containing group removal, together
When cetyl ammonium bromide be also degraded, obtain graphene powder.
The dispersion performance of graphene powder is tested using the method for test case.Sedimentation is observed after 6 hours.
Comparative example 2
(1) oxidation reaction of graphite: with embodiment 1.
(2) stating directly up and 1.5ml concentration is added in the mixed liquor containing graphite oxide, inorganic salts and acid is 10wt%'s
Flocculant " polypropylene-base ammonium chloride " after settling graphite oxide rapid flocculation, pours out supernatant liquor and obtains sediment, wash,
Suction filtration obtains flocculation state graphite oxide filter cake；Isolated flocculation state graphite oxide filter cake is diluted with water to 0.5wt% again,
The graphite oxide of flocculation state uniform can not disperse；Adjusting control agent " ammonium hydroxide " is added later makes system pH be greater than 7, the oxygen for state of flocculating
Graphite can not deflocculation, the graphite oxide aqueous dispersions of uniform dispersion can not be prepared.
(3) reduction reaction: due to the flocculation state graphite oxide can not redisperse, can not deflocculation, therefore, it is impossible to
Graphene is prepared by the reduction reaction under liquid-phase system.
Graphene is prepared by high temperature thermal reduction: obtained flocculation state graphite oxide filter cake will be filtered in step (2) 60
DEG C drying, be placed on the drying of 1000 DEG C of Muffle furnaces thermal reduction 15 seconds, make graphite oxide expansion removing, oxygen-containing group removal, together
When polypropylene-base ammonium chloride be also degraded, obtain graphene powder.
The dispersion performance of graphene powder is tested using the method for test case.Sedimentation is observed after 6 hours.
Claims (7)
1. a kind of preparation method of graphene, characterized by the following steps:
1. the oxidation reaction of graphite；
2. flocculation is conciliate in the flocculation of graphite oxide: controlled flocculation will be added in the mixed liquor containing graphite oxide, inorganic salts and acid
Inorganic agent separates after making graphite oxide flocculating setting；Adjusting control agent releasing is added in isolated flocculation state graphite oxide in water
Flocculation, is prepared finely dispersed graphite oxide dispersion, and the controlled flocculation inorganic agent is to contain aryl and quaternary ammonium simultaneously
The organic matter of group, the adjusting control agent are alkaline solution；
3. reduction reaction.
2. the preparation method of graphene according to claim 1, it is characterised in that: the oxidation reaction of the graphite, be with
Graphite is raw material, is aoxidized with the mixed liquor of strong oxidizer and strong acid, and the mixing containing graphite oxide, inorganic salts and acid is obtained
Liquid.
3. the preparation method of graphene according to claim 1, it is characterised in that: the controlled flocculation inorganic agent is simultaneously
Small organic molecule containing aryl and quaternary ammonium group.
4. the preparation method of graphene according to claim 3, it is characterised in that: the controlled flocculation inorganic agent is benzyl
One of trimethylammonium bromide, benzyltrimethylammonium chloride, phenyltrimethylammonium bromide or phenyl trimethicone ammonium chloride are several
Kind.
5. the preparation method of graphene according to claim 1, it is characterised in that: the adjusting control agent is ammonium hydroxide, hydroxide
One or more of sodium water solution or potassium hydroxide aqueous solution.
6. the preparation method of graphene according to claim 1, it is characterised in that: the reduction reaction is in liquid-phase system
It is lower to be restored using reducing agent.
7. the preparation method of graphene according to claim 6, it is characterised in that: the reducing agent is hydrosulfurous acid
One or more of sodium, potassium hyposulfite or hydrazine hydrate.
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| CN103482613A (en) * | 2013-09-03 | 2014-01-01 | 中国科学院山西煤炭化学研究所 | High-efficiency separation and purification method of graphite oxide |
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| CN103482613A (en) * | 2013-09-03 | 2014-01-01 | 中国科学院山西煤炭化学研究所 | High-efficiency separation and purification method of graphite oxide |
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