WO2015106437A1 - 一种石墨烯量子点的大规模制备方法 - Google Patents

一种石墨烯量子点的大规模制备方法 Download PDF

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WO2015106437A1
WO2015106437A1 PCT/CN2014/070804 CN2014070804W WO2015106437A1 WO 2015106437 A1 WO2015106437 A1 WO 2015106437A1 CN 2014070804 W CN2014070804 W CN 2014070804W WO 2015106437 A1 WO2015106437 A1 WO 2015106437A1
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quantum dots
watts
graphene quantum
dispersion
graphene
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PCT/CN2014/070804
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French (fr)
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张明东
张麟德
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深圳粤网节能技术服务有限公司
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Priority to PCT/CN2014/070804 priority Critical patent/WO2015106437A1/zh
Priority to EP14878575.1A priority patent/EP3085665B1/en
Priority to US15/109,817 priority patent/US9663370B2/en
Priority to JP2016547043A priority patent/JP6271745B2/ja
Publication of WO2015106437A1 publication Critical patent/WO2015106437A1/zh

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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/184Preparation
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/184Preparation
    • C01B32/19Preparation by exfoliation
    • C01B32/192Preparation by exfoliation starting from graphitic oxides
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/194After-treatment
    • C01B32/196Purification
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00Nanotechnology for materials or surface science, e.g. nanocomposites
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00Manufacture or treatment of nanostructures
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    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/65Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S977/00Nanotechnology
    • Y10S977/70Nanostructure
    • Y10S977/734Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S977/00Nanotechnology
    • Y10S977/70Nanostructure
    • Y10S977/773Nanoparticle, i.e. structure having three dimensions of 100 nm or less
    • Y10S977/774Exhibiting three-dimensional carrier confinement, e.g. quantum dots
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S977/00Nanotechnology
    • Y10S977/84Manufacture, treatment, or detection of nanostructure
    • Y10S977/842Manufacture, treatment, or detection of nanostructure for carbon nanotubes or fullerenes

Definitions

  • the invention relates to the technical field of nano material preparation, in particular to a large-scale preparation method of graphene quantum dots.
  • the perfect graphene has an ideal two-dimensional structure. It consists of a hexagonal lattice. Each carbon atom is bonded to the other three carbon atoms in the plane of the lattice plane through the ⁇ bond. The electrons that are not ⁇ bond are used as ⁇ . The electrons form a ⁇ -orbital system perpendicular to the plane of the lattice. The ⁇ electrons can move freely on the plane.
  • the band structure is in the form of a Dirac cone, and at the Dirac point, the conduction band of the graphene and the valence band coincide, so the electron at its Dirac point
  • the effective mass of the holes and the holes are all zero, and the mobility of the corresponding electrons and holes are the same and infinitely close to infinity, which means that the carrier can be either a hole or an electron, and its carrier mobility is extremely high.
  • the carrier can be either a hole or an electron, and its carrier mobility is extremely high.
  • ideal graphene should have excellent electrical conductivity and is predicted to withstand current densities six orders of magnitude higher than copper.
  • Such graphene has a corresponding energy band gap, which results in a laser emission wavelength formed after the exciton de-excitation is excellent, and has excellent laser characteristics.
  • Such graphene particles have characteristics similar to those of semiconductor quantum dots in inorganic materials, so they are called graphene quantum dots, and the radius of graphene quantum dots is within the Bohr radius, which is non-toxic and harmless.
  • the narrow fluorescence wavelength and wide laser wavelength make it an excellent application for light-emitting diodes (LEDs) and bio-imaging as well as photovoltaic devices and sensors.
  • the secondary oxidation method needs to prepare high-quality graphene material first, in order to carry out the subsequent oxidation step, the cost is high, and it is not conducive to industrialization; the process involved in the organic synthesis method is complicated and cumbersome, which is not conducive to industrial production; The method of electron or ion beam etching has the problem of small yield and cannot be mass-produced; the method of micro-cutting carbon materials also has the disadvantages of complicated steps and low yield. Therefore, a simple method and a method for preparing graphene quantum dots on a large scale is proposed, which is imperative for the advancement of quantum dot research.
  • a method for large-scale preparation of graphene quantum dots comprising the following steps:
  • the mixture is reacted in a microwave environment of 500 watts to 800 watts for 10 minutes to 60 minutes, and after cooling, solid-liquid separation is performed, and a solid is obtained to obtain a crude product;
  • the second dispersion is reacted in a microwave environment of 500 watts to 800 watts for 0.2 hours to 1 hour, and then stripped in an ultrasonic environment of 120 watts to 300 watts for 2 hours to 3 hours, and the graphene quantum is obtained after separation and purification. point.
  • the step of ultrasonic stirring before the step of reacting the mixed solution in a microwave environment of 500 watts to 800 watts for 10 minutes to 60 minutes, the step of ultrasonic stirring is performed, and the step of ultrasonic stirring is specifically: The mixture is stirred in an ultrasonic environment of 120 watts to 300 watts for 0.5 hour to 4 hours.
  • the step of ultrasonically dispersing before the step of reacting the second dispersion in a microwave environment of 500 watts to 800 watts for 0.2 hours to 1 hour, the step of ultrasonically dispersing is further included, the step of ultrasonically dispersing is specifically: The second dispersion is dispersed in an ultrasonic environment of 120 watts to 300 watts for 0.5 hours to 2 hours.
  • the first solvent and the second solvent are each selected from the group consisting of water, dimethoxyethane, aqueous solutions of polyvinyl alcohol, glycerol, triethylene glycol, and N-methylpyrrolidone. At least one of them.
  • the concentration of the graphene oxide in the first dispersion is from 2 mg/ml to 10 mg/ml.
  • the reducing agent is selected from at least one of citric acid, gluconic acid, formic acid, ascorbic acid, oxalic acid, sodium citrate, sodium gluconate, sodium formate, sodium ascorbate, and sodium oxalate.
  • the mass ratio of the graphene oxide to the reducing agent is 1:3-10.
  • the operation of reacting the mixed liquid in a microwave environment of 500 watts to 800 watts for 10 minutes to 60 minutes is specifically: mixing the mixed liquid in a microwave environment of 500 watts to 800 watts.
  • the reaction is carried out for 5 minutes to 30 minutes, and after the addition of the first solvent, the reaction is continued for 5 minutes to 30 minutes in a microwave environment of 500 watts to 800 watts; wherein the volume of the first solvent added is the number 10% to 15% of the initial volume of a solvent.
  • the mass ratio of the crude product to one of the reducing polyhydroxy aldehyde and the organic acid is 1:5-10.
  • the reducing polyhydroxy aldehyde is glucose or adipaldehyde.
  • the Lewis acid is selected from at least one of ferric chloride, aluminum chloride, zinc chloride, boron trifluoride, magnesium chloride, copper chloride, and lithium chloride.
  • the organic acid is selected from at least one of citric acid, gluconic acid, formic acid, ascorbic acid, and oxalic acid.
  • the concentration of the mixture in the second dispersion is from 0.1 g/ml to 1 g/ml.
  • the Lewis acid has a mass of from 1% to 3% by mass of the mixture.
  • the step of obtaining the graphene quantum dots after separation and purification is specifically: peeling the reaction product obtained in the ultrasonic environment of 120 watts to 300 watts for 2 hours to 3 hours for column layer Separating and separating, and then vacuum-removing the solvent to obtain the graphene quantum dots; wherein the stationary phase of the column chromatography is silica gel or polyacrylamide, and the first phase developing agent is dichloromethane and methanol by volume ratio 1 : 1 to 3 mixed liquid, the second phase developing agent is deionized water.
  • the above-mentioned large-scale preparation method of graphene quantum dots completes the preparation of a large number of graphene quantum dots by a microwave-solvent method, the process is simple, the cost is effectively reduced, and the reaction amount is large, and the gram level or even the kilogram level can be completed at one time.
  • the preparation of graphene quantum dots enables the preparation of graphene on a large scale. At the same time, after a plurality of strippings, the raw material of graphene oxide can be completely utilized to obtain an extremely high yield.
  • FIG. 1 is a flow chart of a method for large-scale preparation of graphene quantum dots according to an embodiment
  • Example 2 is a fluorescence spectrum diagram of a graphene quantum dot prepared in Example 1;
  • Example 3 is a fluorescence spectrum diagram of the ocene quantum dots prepared in Example 2.
  • Example 4 is a fluorescence spectrum diagram of the ocene quantum dots prepared in Example 3.
  • FIG. 5 is a fluorescence spectrum diagram of the ocene quantum dots prepared in Example 4.
  • FIG. 5 is a fluorescence spectrum diagram of the ocene quantum dots prepared in Example 4.
  • a method for large-scale preparation of graphene quantum dots includes the following steps S110 to S140 .
  • Step S110 adding graphene oxide to the first solvent, uniformly dispersing to obtain a first dispersion liquid, adding the reducing agent to the first dispersion liquid, and uniformly dispersing to obtain a mixed liquid.
  • the graphene oxide is preferably a single layer of graphene oxide prepared by a chemical process that improves Hummers.
  • the first solvent is at least one selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol, glycerin, triethylene glycol, and N-methylpyrrolidone. These solvents have a relatively high boiling point, and a high-boiling solvent can provide a sufficiently high ambient temperature for deoxygenation of graphene oxide, and the above-mentioned high-boiling solvent does not adversely react with graphene oxide.
  • the first solvent is an aqueous solution of polyvinyl alcohol. More preferably, the mass percentage of the aqueous solution of polyvinyl alcohol is 10%.
  • the concentration of graphene oxide in the first dispersion is from 2 mg/ml to 10 mg/ml.
  • the reducing agent is selected from at least one of citric acid, gluconic acid, formic acid, ascorbic acid, oxalic acid, sodium citrate, sodium gluconate, sodium formate, sodium ascorbate, and sodium oxalate.
  • the reducing agent is oxalic acid.
  • the mass ratio of graphene oxide to reducing agent is 1:3-10.
  • the mass ratio is selected to partially reduce the graphene oxide, so that the partially reduced graphene oxide has less oxygen, but still retains part of oxygen.
  • the graphene oxide destroys the graphene Dirac due to the introduction of oxygen.
  • the cone makes the energy band of the graphene discontinuous, and has a possible semiconductor structure, which is favorable for the subsequent formation of higher quality graphene quantum dots.
  • the reducing agent is added to the first dispersion to obtain a mixture of the reducing agent and the first dispersion, and the mixture of the reducing agent and the first dispersion is ultrasonically dispersed to uniformly disperse the graphene oxide and the reducing agent to obtain a mixed solution.
  • Step S120 reacting the mixed solution in a microwave environment of 500 watts to 800 watts for 10 minutes to 60 minutes, cooling and then separating the solid and liquid, and taking the filter cake to obtain a crude product.
  • the step of ultrasonic agitation is also included prior to reacting the mixture in a microwave environment.
  • the ultrasonic stirring step is specifically: stirring the mixed solution in an ultrasonic environment of 120 watts to 300 watts for 0.5 hour to 4 hours.
  • the purpose of ultrasonic agitation is to strip the reduced graphene oxide which may be agglomerated, and to promote the destruction of graphene oxide after reduction, thereby forming quantum dots.
  • the mixture is stirred for 0.5 hour to 4 hours in an ultrasonic environment of 120 watts to 300 watts to ensure complete ablation of the reduced graphene oxide and aggravation of the reduced graphene oxide to ensure the formation of graphene quantum dots.
  • the ultrasonically stirred mixture is reacted in a microwave environment to subject the graphene oxide to microwave-solvent thermal reduction cracking.
  • the reduction under microwave-solvothermal conditions effectively reduces the cracking of graphene oxide, thereby reducing the size of the graphene sheet layer and facilitating the control of the size of the graphene quantum dots in the next step.
  • the operation of reacting the mixed solution in a microwave environment of 500 watts to 800 watts for 10 minutes to 60 minutes is specifically: placing the mixed solution in a closed reaction vessel and reacting in a microwave environment of 500 watts to 800 watts. Minutes ⁇ 30 minutes, after taking out the first solvent, continue to react in a microwave environment of 500 watts to 800 watts for 5 minutes to 30 minutes.
  • the volume of the added first solvent is 10% to 15% of the initial volume of the first solvent.
  • the mixture is subjected to a microwave-solvothermal reaction in two steps, and after the first step of the reaction is completed, the first solvent is added and then the second step is carried out.
  • the solid-liquid separation operation is specifically: the reaction liquid is cooled, deionized water is added to the reaction liquid to obtain a reactant dispersion liquid, and the reactant dispersion liquid is ultrasonically dispersed in an ultrasonic environment of 120 watts to 300 watts for 5 minutes to 30 minutes. Then, suction filtration was carried out to obtain a filtrate and a cake, and the cake was taken to obtain a crude product. The filtrate is retained to further separation in subsequent step S140.
  • the initial volume ratio of deionized water to the first solvent added to the reaction solution is 1:10-20.
  • the filtrate is a solution of smaller size graphene quantum dots.
  • the filter cake, the crude product is a larger size graphene quantum dot.
  • the subsequent steps S130 and S140 are performed to obtain graphene quantum dots of a desired size.
  • Step S130 mixing one of the reducing polyhydroxy aldehyde and the organic acid with the crude product, adding a Lewis acid, uniformly mixing to obtain a mixture, adding the mixture to the second solvent, and uniformly dispersing to obtain a second dispersion.
  • the reducing polyhydroxy aldehyde is preferably a six-membered ring saccharide, and more preferably glucose or adipaldehyde.
  • Glucose and adipaldehyde act as reducing agents on the one hand and carbon rings on graphene quantum dots on the other hand as carbon sources.
  • Glucose or adipaldehyde a six-membered ring sugar, has a six-membered ring structure that matches the structure of graphene. It does not introduce Stone-Wales topological defects on the graphene structure to ensure the final prepared graphene. Quantum dots have a higher quality.
  • the organic acid is selected from at least one of citric acid, gluconic acid, formic acid, ascorbic acid, and oxalic acid.
  • the second solvent is at least one selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol, glycerin, triethylene glycol, and N-methylpyrrolidone.
  • the Lewis acid is at least one selected from the group consisting of ferric chloride, aluminum chloride, zinc chloride, boron trifluoride, magnesium chloride, copper chloride, and lithium chloride.
  • the reducing polyhydroxy aldehyde is mixed with the crude product, a Lewis acid is added, and the mixture is uniformly mixed to obtain a mixture, and the mixture is added to the second solvent to be uniformly dispersed to obtain a second dispersion.
  • the mass ratio of the crude product to the reducing polyhydroxy aldehyde is 1:5-10.
  • the mass of the Lewis acid is from 1% to 3% by mass of the mixture of the reducing polyhydroxy aldehyde, the crude product and the Lewis acid.
  • the organic acid is mixed with the crude product, a Lewis acid is added, and the mixture is uniformly mixed to obtain a mixture, and the mixture is added to the second solvent to be uniformly dispersed to obtain a second dispersion.
  • the mass ratio of the crude product to the organic acid is 1:5-10.
  • the mass of the Lewis acid is from 1% to 3% by mass of the mixture of the organic acid, the crude product and the Lewis acid.
  • One of the reducing polyhydroxy aldehyde and the organic acid is mixed with the crude product, a Lewis acid is added, and the mixture is uniformly mixed to obtain a mixture, and the mixture is added to a second solvent to be uniformly dispersed in an ultrasonic environment to obtain a second dispersion.
  • the concentration of the mixture of the reduced polyhydroxy aldehyde and the organic acid, the crude product and the Lewis acid is from 0.1 g/mL to 1 g/mL.
  • Step S140 reacting the second dispersion in a microwave environment of 500 watts to 800 watts for 0.2 hours to 1 hour, and then performing stripping in an ultrasonic environment of 120 watts to 300 watts for 2 hours to 3 hours, and separating and purifying to obtain graphene quantum. point.
  • the step of ultrasonic dispersion is further included before the second dispersion is reacted in a microwave environment.
  • the ultrasonic dispersion step is specifically: dispersing the second dispersion in an ultrasonic environment of 120 watts to 300 watts for 0.5 hours to 2 hours, so that one of the reducing polyhydroxy aldehyde and the organic acid in the second dispersion is The crude product and the Lewis acid are uniformly dispersed to facilitate the reaction.
  • the ultrasonically dispersed second dispersion is reacted in a microwave environment of 500 watts to 800 watts for 0.2 hours to 1 hour, and then dispersed and stripped in an ultrasonic environment of 120 watts to 300 watts for 2 hours to 3 hours, and is obtained after separation and purification.
  • Graphene quantum dots of the desired size are obtained after separation and purification.
  • the reaction liquid obtained by the microwave reaction is diluted by adding deionized water, and then Dispersion and stripping were carried out in an ultrasonic environment of 120 watts to 300 watts for 2 hours to 3 hours to obtain an aqueous solution of graphene quantum dots.
  • the volume ratio of the deionized water to the second solvent of the second dispersion is preferably 1:10 to 20.
  • Step S130 and step S140 wherein the graphene quantum dots are prepared by a hydrothermal method using a reducing polyhydroxy aldehyde as a carbon source, and the graphene particles are used as a nucleation source of the quantum dots, thereby effectively increasing the size of the graphene quantum dots.
  • the corresponding red shift of the fluorescence spectrum Thereby, yellow to red graphene quantum dots can be obtained.
  • the graphene oxide quantum dots are prepared by the solvothermal heat of the second solvent in the organic acid environment and the high frequency ultrasonic is used as the carbon layer cracking method, and the graphene particles are used as the nucleation source of the quantum dots,
  • the second solvent protects the quantum dots, thereby effectively reducing the size of the graphene quantum dots, which corresponds to the blue shift of the fluorescence spectrum. Thereby, green and blue graphene quantum dots can be obtained.
  • the separation and purification operation is specifically performed by subjecting an aqueous solution of graphene quantum dots to column chromatography, sequentially obtaining an aqueous solution of graphene quantum dots having different particle diameters, and vacuuming the obtained aqueous solutions of graphene quantum dots having different particle sizes.
  • the solvent was distilled off to obtain dried graphene quantum dot powders having different particle sizes.
  • the graphite quantum dot solution in the aqueous phase is first extracted by a mixed solvent of dichloromethane and methanol in a volume ratio of 1:1 to 3:1, and then the solvent is distilled off to obtain a size. Small graphene quantum dot powder.
  • the stationary phase of the column chromatography is silica gel or polyacrylamide.
  • the first phase developing agent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:1 to 3, and the second phase developing agent is deionized water.
  • the filtrate prepared in step S120 that is, the solution of graphene quantum dots is also separated by the above-mentioned column chromatography separation method, and vacuum-depleted to remove the solvent to obtain a dried graphene quantum dot powder to improve the yield.
  • the above-mentioned large-scale preparation method of graphene quantum dots completes the preparation of a large number of graphene quantum dots by a microwave-solvent method, the process is simple, the cost is effectively reduced, and the reaction amount is large, and the gram level or even the kilogram level can be completed at one time.
  • the preparation of graphene quantum dots enables the preparation of graphene on a large scale. At the same time, after multiple stripping and multiple reductions in size, the raw material of graphene oxide can be fully utilized to obtain an extremely high yield.
  • the above-mentioned large-scale preparation method of graphene quantum dots can control the size of graphene quantum dots by hydrothermal method using reduced polyhydroxy aldehyde as carbon source or solvothermal method in organic acid environment, and can control graphite well.
  • the size of the ene quantum dots can be Good control, which is conducive to continuous mass production.
  • the mixture was ultrasonically dispersed in a 120 W ultrasonic environment for 4 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 500 W for 30 min; the dimethoxyethane was added, and the dimethoxy group was added.
  • the volume of ethane is 15% of the volume of the initial dimethoxyethane in the first dispersion; the reaction is continued for 10 minutes in a microwave environment of 500 W. After the reaction is completed, the reaction solution is cooled and added to the reaction solution.
  • Ionic water volume ratio of deionized water to initial dimethoxyethane in the first dispersion was 1:10) to obtain a reactant dispersion, and the reactant dispersion was ultrasonically dispersed in a 120 W ultrasonic environment for 30 minutes. Then, suction filtration is performed, and the filtrate is taken to obtain a solution of graphene quantum dots, which is used; the filter cake is taken to obtain a crude product;
  • the second dispersion was dispersed in a 120 W ultrasonic environment for 2 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 500 W for 1 hour. After adding the deionized water, the reaction solution obtained by the microwave reaction was diluted (go. The volume ratio of ionized water to N-methylpyrrolidone in the second dispersion is 1:15), and then dispersed and stripped in an ultrasonic environment of 300 W for 2 hours to obtain an aqueous solution of graphene quantum dots, and the graphene quantum dots are obtained.
  • the aqueous solution and the solution of graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:3.
  • the second phase developing agent is deionized water; a column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle diameters; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:3.
  • the solution of the quantum dots is subjected to vacuum distillation to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is mixed by a ratio of dichloromethane to methanol by 1:1. Extraction agent, and then the solvent was distilled off by rotary evaporation, to obtain graphene quantum dots dried powder.
  • FIG. 2 is a fluorescence spectrum diagram of the graphene quantum dots prepared in the first embodiment. As can be seen from FIG. 2, the fluorescence emission wavelength of the obtained graphene quantum dots prepared in the present Example 1 was about 435 nm.
  • the mixture was ultrasonically dispersed in a 150 W ultrasonic environment for 1 hour, placed in a closed reaction vessel, and reacted in a microwave environment of 700 W for 20 min; and the triethylene glycol and N were added in a volume ratio of 1:1.
  • a mixed solvent of methylpyrrolidone a volume ratio of a mixed solvent of triethylene glycol and N-methylpyrrolidone added in a volume ratio of 1:1 is an initial volume ratio of 1:1 in the first dispersion 12% by volume of the mixed solvent of triethylene glycol and N-methylpyrrolidone; continue to react in a microwave environment of 700 W for 20 min. After the reaction is completed, the reaction solution is cooled, and deionized water (deionized) is added to the reaction solution.
  • a volume ratio of water to the mixed solvent of triethylene glycol and N-methylpyrrolidone in an initial volume ratio of 1:1 in the first dispersion is 1:20) to obtain a reactant dispersion, and a reactant dispersion Ultrasonic dispersion in a 300 W ultrasonic environment for 15 minutes, followed by suction filtration, taking the filtrate to obtain a solution of graphene quantum dots, and standby; taking the filter cake to obtain a crude product;
  • the second dispersion was dispersed in a 180 W ultrasonic environment for 1.5 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 550 W for 0.5 hours, and deionized water was added to dilute the reaction solution obtained by the microwave reaction (go.
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:15), and then dispersed and stripped in an ultrasonic environment of 180 W for 3 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of the graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle sizes; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the solution of the olefin quantum dots is evaporated under vacuum to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a ratio of 2:1 by volume of dichloromethane and methanol. mixing
  • the solvent is subjected to extraction, and the solvent is further evaporated to obtain a dried graphene quantum dot powder.
  • FIG. 3 is a fluorescence spectrum diagram of the graphene quantum dots prepared in Example 2. As can be seen from FIG. 3, the obtained graphene quantum dots prepared by the present Example 2 have a fluorescence emission wavelength of about 380 nm.
  • the mixture was ultrasonically dispersed in a 200 W ultrasonic environment for 3 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 650 W for 8 minutes; water was added and the volume of water added was in the first dispersion. 10% of the initial water volume; continue to react in a microwave environment of 650 W for 8 min. After the reaction is completed, the reaction solution is cooled, and deionized water (deionized water and initial water in the first dispersion liquid) is added to the reaction liquid.
  • the volume ratio is 1:10), the reactant dispersion is obtained, and the reactant dispersion is ultrasonically dispersed in a ultrasonic environment of 150 W for 18 minutes, and then subjected to suction filtration, and the filtrate is taken to obtain a solution of graphene quantum dots, which is ready for use; a cake to obtain a crude product;
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:10), and then dispersed and stripped in an ultrasonic environment of 270 W for 3 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of the graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle sizes; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the solution of the olefin quantum dots is evaporated under vacuum to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a ratio of 2:1 by volume of dichloromethane and methanol.
  • Example 4 is a fluorescence spectrum diagram of the graphene quantum dots prepared in Example 3. As can be seen from FIG. 4, the obtained graphene quantum dots prepared by the method have a fluorescence emission wavelength of about 390 nm.
  • the mixture was ultrasonically dispersed in a 200 W ultrasonic environment for 2 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 600 W for 10 min; the glycerol was added and the volume of the added glycerol was 10% of the volume of the initial glycerol in a dispersion; continue to react in a microwave environment of 600 W for 10 min.
  • the reaction solution is cooled, and deionized water (deionized water and first) is added to the reaction solution.
  • the volume ratio of the initial glycerol in the dispersion was 1:15), the reactant dispersion was obtained, and the reactant dispersion was ultrasonically dispersed in a 180 W ultrasonic environment for 20 minutes, followed by suction filtration, and the filtrate was taken to obtain graphene. a solution of quantum dots, spare; take the filter cake to obtain a crude product;
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:15), and then dispersed and stripped in an ultrasonic environment of 180 W for 3 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of the graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle sizes; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the solution of the olefin quantum dots is evaporated under vacuum to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a ratio of 2:1 by volume of dichloromethane and methanol.
  • FIG. 5 is a fluorescence spectrum diagram of the graphene quantum dots prepared in Example 4. As can be seen from FIG. 5, the obtained graphene quantum dots prepared by the method have a fluorescence emission wavelength of about 410 nm.
  • the mixture was ultrasonically dispersed in a 120 W ultrasonic environment for 4 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 500 W for 30 min; the dimethoxyethane was added, and the dimethoxy group was added.
  • the volume of ethane is 15% of the volume of the initial dimethoxyethane in the first dispersion; the reaction is continued for 10 minutes in a microwave environment of 500 W. After the reaction is completed, the reaction solution is cooled and added to the reaction solution.
  • Ionic water volume ratio of deionized water to initial dimethoxyethane in the first dispersion was 1:10) to obtain a reactant dispersion, and the reactant dispersion was ultrasonically dispersed in a 280 W ultrasonic environment for 5 minutes. Then, suction filtration is performed, and the filtrate is taken to obtain a solution of graphene quantum dots, which is used; the filter cake is taken to obtain a crude product;
  • the second dispersion was dispersed in a 120 W ultrasonic environment for 2 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 500 W for 1 hour. After adding the deionized water, the reaction solution obtained by the microwave reaction was diluted (go.
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:20), and then dispersed and stripped in an ultrasonic environment of 300 W for 2 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:3.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle sizes; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:3.
  • the solution of the olefin quantum dots is subjected to vacuum distillation to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a volume ratio of 1:1 to methylene chloride and methanol. Mixed solution It was extracted, and then the solvent was distilled off by rotary evaporation, to obtain graphene quantum dots dried powder.
  • the mixture was ultrasonically dispersed in a 300 W ultrasonic environment for 0.4 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 800 W for 5 min; and an aqueous solution of polyvinyl alcohol having a mass concentration of 10% was taken out and added.
  • the volume of the aqueous solution of polyvinyl alcohol having a mass concentration of 10% is 10% of the volume of the aqueous solution of polyvinyl alcohol having an initial mass concentration of 10% in the first dispersion; the reaction is continued for 5 minutes in a microwave environment of 800 W, After the reaction is completed, the reaction solution is cooled, and deionized water (volume ratio of deionized water to an aqueous solution of polyvinyl alcohol having an initial mass concentration of 10% in the first dispersion liquid of 1:12) is added to the reaction liquid.
  • reaction dispersion was ultrasonically dispersed in a 200 W ultrasonic environment for 30 minutes, and then subjected to suction filtration, and the filtrate was taken to obtain a solution of graphene quantum dots, which was used; the filter cake was taken to obtain a crude product;
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:15), and then dispersed and stripped in an ultrasonic environment of 120 W for 3 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of the graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:1.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle diameters; and the solvent is a mixture of dichloromethane and methanol mixed in a volume ratio of 1:1.
  • the solution of the olefin quantum dots is subjected to vacuum distillation to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a volume ratio of 1:1 to methylene chloride and methanol. mixing
  • the solvent is subjected to extraction, and the solvent is further evaporated to obtain a dried graphene quantum dot powder.
  • the mixture was ultrasonically dispersed in a 250 W ultrasonic environment for 2.5 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 550 W for 25 min; the triethylene glycol was added and the triplet was added.
  • the volume of the diol is 13% of the volume of the initial triethylene glycol in the first dispersion; the reaction is continued for 25 minutes in a microwave environment of 550 W, and after the reaction is completed, the reaction solution is cooled and added to the reaction solution.
  • the second dispersion was dispersed in a 150 W ultrasonic environment for 1.8 hours, placed in a closed reaction vessel, and reacted in a microwave environment of 750 W for 0.4 hours. After adding the deionized water, the reaction solution obtained by the microwave reaction was diluted (go.
  • the volume ratio of ionized water to dimethoxyethane in the second dispersion is 1:15), and then dispersed and stripped in an ultrasonic environment of 250 W for 2.5 hours to obtain an aqueous solution of graphene quantum dots, and graphene quantum
  • the aqueous solution of the point and the solution of the graphene obtained in the above step 2 are subjected to column chromatography, wherein the stationary phase of the column chromatography is silica gel, and the first phase developing agent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the second phase developing agent is deionized water; the column chromatography is sequentially performed to obtain a solution of graphene quantum dots having different particle sizes; and the solvent is a mixture of dichloromethane and methanol in a volume ratio of 1:2.
  • the solution of the olefin quantum dots is evaporated under vacuum to remove the solvent to obtain a dried graphene quantum dot powder; the solution of the graphene quantum dots in which the solvent is deionized water is passed through a ratio of 2:1 by volume of dichloromethane and methanol.

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Abstract

一种石墨烯量子点的大规模制备方法,包括:将氧化石墨烯加入第一溶剂中,得到第一分散液,将还原剂加入第一分散液中,得到混合液;将混合液于微波环境中反应,冷却后进行固液分离,取固体,得到粗产物;将还原性多羟基醛及有机酸中的一种与粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将混合物加入第二溶剂中,得到第二分散液;及将第二分散液于微波环境中反应,然后于超声环境下剥离,分离纯化后得到石墨烯量子点。通过微波-溶剂热的方法完成大规模制备,工艺简单且氧化石墨烯利用率高,产率高。

Description

一种石墨烯量子点的大规模制备方法
【技术领域】
本发明涉及纳米材料制备技术领域,特别是涉及一种石墨烯量子点的大规模制备方法。
【背景技术】
自从2004年英国曼彻斯特大学的Andre Geim及Konstantin Novoselof首次成功剥离热解石墨并观测到石墨烯以来,学界内对于新型碳材料的研究热度就一直没有消退过。石墨烯的成功分离意味着理论对于二维晶体热力学不稳定的预言被破除,也就带来了许多新领域研究的可能。
完美的石墨烯具有理想的二维结构,它由六边形晶格组成,每个碳原子通过σ键在晶格平面方向上与其他的三个碳原子结合,未成σ键的电子则作为π电子,组成了垂直于晶格平面的π轨道体系。π电子可在平面上任意移动。但更为重要的是,由于石墨烯特有的结构,其能带结构呈狄拉克锥的形式,而在狄拉克点上,石墨烯的导带和价带重合,因此在其狄拉克点上电子和空穴的有效质量皆为零,对应的电子和空穴的迁移率都相同且无限接近于无穷大,这意味着其载子既可以是空穴也可以是电子,且其载子迁移率极大,因此理想的石墨烯应当具有极好的导电性,预测其能够承受比铜高六个数量级的电流密度。
目前的研究对于大片层的石墨烯已经有一系列激动人心的研究工作已经发表,而对于二维的片层尺度大小被束缚在玻尔半径的石墨烯及氧化石墨烯颗粒的研究,也正如火如荼的进行着。对于这样的石墨烯颗粒,由于保留了一定的氧化官能团或缺陷,且尺寸变小,故其能带并非连续,由此导致其载子可被激发。载子被激发后形成激子,而激子又被限制在了该石墨烯的三个空间方向的能带隙里,单层石墨烯厚度在1nm左右,片层大小在玻尔半径左右,由于这样的石墨烯对应的能带隙较大,这导致激子退激发后形成的激光发射波长较宽,具有极好的激光特性。而这类石墨烯颗粒,有类似无机材料中的半导体量子点所具有的特性,因此被称之为石墨烯量子点,石墨烯量子点的半径在波尔半径之内,其无毒无害,荧光波长窄,激光波长宽,在发光二级管(LED)和生物成像以及光伏器件和传感器上能起到极好的应用。
目前对于石墨烯量子点的研究中,主要采用的制备方法有四种。这四种方法分别是对石墨烯进行再氧化的二次氧化法、从有机小分子出发的有机合成法、电子束或离子束蚀刻的方法以及对碳材料进行微观切割的方法。这当中,二次氧化法需要先制备出高品质的石墨烯材料,才能进行好后续的氧化步骤,成本较高,也不利于工业化;有机合成法所涉及工艺复杂且繁琐,不利于工业生产;电子或离子束蚀刻的方法则存在产量小,无法大批量生产的问题;对碳材料进行微观切割的方法也存在步骤复杂且产率较低的缺陷。因此,提出一种工艺简单,且能够大规模制备石墨烯量子点的方法,对于推动量子点研究的进展,是势在必行的。
【发明内容】
基于此,有必要提供一种工艺简单、产率较高的石墨烯量子点的大规模制备方法,以大规模制备石墨烯量子点。
一种石墨烯量子点的大规模制备方法,包括如下步骤:
将氧化石墨烯加入第一溶剂中,均匀分散得到第一分散液,将还原剂加入所述第一分散液中,均匀分散得到混合液;
将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟,冷却后进行固液分离,取固体,得到粗产物;
将还原性多羟基醛及有机酸中的一种与所述粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将所述混合物加入第二溶剂中,均匀分散得到第二分散液;及
将所述第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时,然后于120瓦~300瓦的超声环境下剥离2小时~3小时,分离纯化后得到所述石墨烯量子点。
在其中一个实施例中,将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟的步骤之前,包括超声搅拌的步骤,所述超声搅拌的步骤具体为:将所述混合液于120瓦~300瓦的超声环境下搅拌0.5小时~4小时。
在其中一个实施例中,将所述第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时的步骤之前,还包括超声分散的步骤,所述超声分散的步骤具体为:将所述第二分散液于120瓦~300瓦的超声环境中分散0.5小时~2小时。
在其中一个实施例中,所述第一溶剂和第二溶剂均选自水、二甲氧基乙烷、聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。
在其中一个实施例中,所述第一分散液中,所述氧化石墨烯的浓度为2毫克/毫升~10毫克/毫升。
在其中一个实施例中,所述还原剂选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸、草酸、柠檬酸钠、葡萄糖酸钠、甲酸钠、抗坏血酸钠及草酸钠中的至少一种。
在其中一个实施例中,所述氧化石墨烯与所述还原剂的质量比为1:3~10。
在其中一个实施例中,所述将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟的操作具体为:将所述混合液于500瓦~800瓦的微波环境中反应5分钟~30分钟,取出补加所述第一溶剂后,继续于500瓦~800瓦的微波环境中反应5分钟~30分钟;其中,所补加的第一溶剂的体积为所述第一溶剂的初始体积的10%~15%。
在其中一个实施例中,所述粗产物与所述还原性多羟基醛及有机酸中的一种的质量比为1:5~10。
在其中一个实施例中,所述还原性多羟基醛为葡萄糖或己二醛。
在其中一个实施例中,所述路易斯酸选自氯化铁、氯化铝、氯化锌、三氟化硼、氯化镁、氯化铜及氯化锂中的至少一种。
在其中一个实施例中,所述有机酸选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸及草酸中的至少一种。
在其中一个实施例中,所述第二分散液中,所述混合物的浓度为0.1克/毫升~1克/毫升。
在其中一个实施例中,所述路易斯酸的质量占所述混合物的质量的1%~3%。
在其中一个实施例中,所述分离纯化后得到所述石墨烯量子点的步骤具体为:将所述于120瓦~300瓦的超声环境下剥离2小时~3小时得到的反应产物进行柱层析分离,然后真空旋蒸除去溶剂,得到所述石墨烯量子点;其中,所述柱层析的固定相为硅胶或聚丙烯酰胺,第一相展开剂为二氯甲烷和甲醇按体积比1:1~3进行混合的混合液,第二相展开剂为去离子水。
上述石墨烯量子点的大规模制备方法通过微波-溶剂热的方法完成了石墨烯量子点的大量制备,工艺简单,有效地降低了成本,且反应量大,能够一次完成克级甚至是千克级的石墨烯量子点的制备,能够大规模制备石墨烯。同时,经过多次剥离后,可以将原料的氧化石墨烯完全利用,获得极高的产率。
【附图说明】
图1为一实施方式的石墨烯量子点的大规模制备方法的流程图;
图2为实施例1制备得到的石墨烯量子点的荧光光谱图;
图3为实施例2制备得到的墨烯量子点的荧光光谱图;
图4为实施例3制备得到的墨烯量子点的荧光光谱图;
图5为实施例4制备得到的墨烯量子点的荧光光谱图。
【具体实施方式】
为使本发明的上述目的、特征和优点能够更加明显易懂,下面结合附图对本发明的具体实施方式做详细的说明。在下面的描述中阐述了很多具体细节以便于充分理解本发明。但是本发明能够以很多不同于在此描述的其它方式来实施,本领域技术人员可以在不违背本发明内涵的情况下做类似改进,因此本发明不受下面公开的具体实施的限制。
请参阅图1,一实施方式的石墨烯量子点的大规模制备方法,包括如下步骤S110~步骤S140。
步骤S110:将氧化石墨烯加入第一溶剂中,均匀分散得到第一分散液,将还原剂加入第一分散液中,均匀分散得到混合液。
氧化石墨烯优选为由改进Hummers的化学法制备的单层氧化石墨烯。
第一溶剂选自水、二甲氧基乙烷、聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。这几种溶剂的沸点较高,高沸点的溶剂可以提供足够高的使氧化石墨烯脱氧还原的环境温度,并且上述高沸点的溶剂与氧化石墨烯无不良反应。
优选地,第一溶剂为聚乙烯醇的水溶液。更优选地,聚乙烯醇的水溶液的质量百分数为10%。
优选地,第一分散液中,氧化石墨烯的浓度物2毫克/毫升~10毫克/毫升。
还原剂选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸、草酸、柠檬酸钠、葡萄糖酸钠、甲酸钠、抗坏血酸钠及草酸钠中的至少一种。优选地,还原剂为草酸。
优选地,氧化石墨烯与还原剂的质量比为1:3~10。选用该质量比,以将氧化石墨烯部分还原,使得经过部分还原后的氧化石墨烯的含氧量较少,但仍保留了部分氧,氧化石墨烯由于氧的引入破坏了石墨烯的狄拉克锥,使得石墨烯的能带不连续,才具有可能的半导体结构,有利于后续形成质量较高的石墨烯量子点。
将还原剂加入第一分散液中得到还原剂与第一分散液的混合物,将还原剂与第一分散液的混合物进行超声分散,使氧化石墨烯与还原剂均匀分散,得到混合液。
步骤S120:将混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟,冷却后进行固液分离,取滤饼,得到粗产物。
优选地,将混合液于微波环境中反应之前,还包括超声搅拌的步骤。超声搅拌的步骤具体为:将混合液于120瓦~300瓦超声环境下搅拌0.5小时~4小时。
超声搅拌的目的是剥离可能团聚的还原后的氧化石墨烯,以及促进还原后的氧化石墨烯的破坏,从而使量子点的形成。在120瓦~300瓦超声环境下搅拌0.5小时~4小时,以保证完全剥离团聚的还原后的氧化石墨烯,并对还原后的氧化石墨烯进行破坏,以保证石墨烯量子点的生成。
将超声搅拌后的混合液置于微波环境中反应,以将氧化石墨烯进行微波-溶剂热还原裂解。在微波-溶剂热条件下进行还原,有效地将氧化石墨烯还原裂解,从而减低石墨烯片层的大小,便于下一步的石墨烯量子点尺寸的控制。
优选地,将混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟的操作具体为:将混合液放入密闭的反应容器中,于500瓦~800瓦的微波环境中反应5分钟~30分钟,取出补加第一溶剂后,继续于500瓦~800瓦的微波环境中反应5分钟~30分钟。其中,所补加的第一溶剂的体积为第一溶剂的初始体积的10%~15%。
在密闭的反应容器中于500瓦~800瓦的微波环境中反应5分钟~30分钟后,部分第一溶剂会在微波-溶剂热的反应过程中直接分解沉降碳在反应物上,所以需要补加第一溶剂维持蒸汽压以利于反应的进行。因此,将混合液分两步进行微波-溶剂热反应,并在第一步反应完成后,补加第一溶剂后再进行第二步反应。
反应结束后,固液分离,取固体,得到粗产物。固液分离的操作具体为:待反应液冷却,向反应液中加入去离子水,得到反应物分散液,将反应物分散液于120瓦~300瓦的超声环境中超声分散5分钟~30分钟,然后进行抽滤,得到滤液和滤饼,取滤饼,得到粗产物。保留滤液至后续步骤S140中进一步分离。
向反应液中加入的去离子水与第一溶剂的初始的体积比为1:10~20。
滤液为尺寸较小的石墨烯量子点的溶液。滤饼,即粗产物为尺寸较大的石墨烯量子点。为了进一步控制石墨烯量子点的尺寸,进行后续步骤S130和步骤S140,以得到所需尺寸的石墨烯量子点。
步骤S130:将还原性多羟基醛及有机酸中的一种与粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将混合物加入第二溶剂中,均匀分散得到第二分散液。
还原性多羟基醛优选为六元环的糖类,进一步优选为葡萄糖或己二醛。葡萄糖和己二醛一方面作为还原剂,另一方面也作为碳源在石墨烯量子点上补充碳环。
选用葡萄糖或己二醛这种具有六元环的糖类,其六元环结构与石墨烯的结构相匹配,不会在石墨烯结构上引入Stone-Wales拓扑缺陷,保证最终制备得到的石墨烯量子点具有较高的质量。
有机酸选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸及草酸中的至少一种。
第二溶剂选自水、二甲氧基乙烷、聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。
路易斯酸选自氯化铁、氯化铝、氯化锌、三氟化硼、氯化镁、氯化铜及氯化锂中的至少一种。
希望增大量子点尺寸时,将还原性多羟基醛与粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将混合物加入第二溶剂中,均匀分散得到第二分散液。
优选地,粗产物与还原性多羟基醛的质量比为1:5~10。优选地,路易斯酸的质量是还原性多羟基醛、粗产物和路易斯酸的混合物的质量的1%~3%。
希望减小量子点尺寸时,将有机酸与粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将混合物加入第二溶剂中,均匀分散得到第二分散液。
优选地,粗产物与有机酸的质量比为1:5~10。优选地,路易斯酸的质量是有机酸、粗产物和路易斯酸的混合物的质量的1%~3%。
将还原性多羟基醛及有机酸中的一种与粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将混合物加入第二溶剂中,于超声环境下均匀分散得到第二分散液。
优选地,第二分散液中,还原性多羟基醛及有机酸中的一种、粗产物和路易斯酸的混合物的浓度为0.1g/mL~1g/mL。
步骤S140:将第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时,然后于120瓦~300瓦的超声环境下进行剥离2小时~3小时,分离纯化后得到石墨烯量子点。
优选地,在将第二分散液于微波环境中进行反应之前,还包括超声分散的步骤。超声分散的步骤具体为:将第二分散液于120瓦~300瓦的超声环境中分散0.5小时~2小时,以使第二分散液中的还原性多羟基醛及有机酸中的一种、粗产物和路易斯酸均匀分散,有利于反应。
将超声分散后的第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时,然后于120瓦~300瓦的超声环境下进行分散和剥离2小时~3小时,分离纯化后得到所需尺寸的石墨烯量子点。
优选地,将第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时后,为了便于后续分散和剥离,先加入去离子水将微波反应得到的反应液进行稀释后,再于120瓦~300瓦的超声环境下进行分散和剥离2小时~3小时,得到石墨烯量子点的水溶液。
去离子水与第二分散液的第二溶剂的体积比优选为1:10~20。
步骤S130和步骤S140以还原性多羟基醛为碳源的水热法制备石墨烯量子点,再利用石墨烯颗粒作为量子点的成核源,有效地增大了石墨烯量子点的尺寸,其对应的荧光光谱的红移。由此,可以获得黄色到红色的石墨烯量子点。
或者,步骤S130和步骤S140以有机酸环境下的第二溶剂的溶剂热和大频率超声为碳层裂解的方法制备氧化石墨烯量子点,再利用石墨烯颗粒作为量子点的成核源,以第二溶剂保护量子点,从而有效地减少了石墨烯量子点的尺寸,其对应的荧光光谱的蓝移。由此,可以获得绿色和蓝色的石墨烯量子点。
分离纯化的操作具体为:将石墨烯量子点的水溶液进行柱层析,依次得到粒径大小不同的石墨烯量子点的水溶液,分别将得到的粒径大小不同的石墨烯量子点的水溶液进行真空旋蒸蒸去溶剂,分别得到干燥的、粒径大小不同的石墨烯量子点粉末。
优选地,为了方便蒸除溶剂,水相中的石墨量子点溶液首先通过二氯甲烷和甲醇按体积比为1:1~3:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得尺寸小的石墨烯量子点粉末。
优选地,柱层析的固定相为硅胶或聚丙烯酰胺。第一相展开剂为二氯甲烷和甲醇按体积比为1:1~3混合的混合液,第二相展开剂为去离子水。
以柱层析而不是渗析的方式进行分离纯化,可以有效地提高产率,同时加快反应速度。同样,由于层析柱可以通过紫外光观察到石墨烯量子点在柱上的移动,从而能有效地获得石墨烯量子点颗粒。
优选地,步骤S120制备得到的滤液,即石墨烯量子点的溶液也采用上述柱层析分离的方法进行分离,并进行真空蒸蒸去溶剂,得到干燥的石墨烯量子点粉末,提高产率。
上述石墨烯量子点的大规模制备方法通过微波-溶剂热的方法完成了石墨烯量子点的大量制备,工艺简单,有效地降低了成本,且反应量大,能够一次完成克级甚至是千克级的石墨烯量子点的制备,能够大规模制备石墨烯。同时,经过多次剥离和多次减小尺寸后,可以将原料的氧化石墨烯完全利用,获得极高的产率。
上述石墨烯量子点的大规模制备方法用还原性多羟基醛作为碳源的水热法或采用在有机酸环境下的溶剂热法对石墨烯量子点的尺寸进行控制,能够较好地控制石墨烯量子点的尺寸。控制性好,有利于进行连续批量生产。
以下通过具体实施例进一步阐述。
实施例1
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于二甲氧基乙烷中,均匀分散得到单层氧化石墨烯的浓度为2mg/mL的第一分散液,将草酸加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与草酸的质量比为1:3;
2、将该混合液于120W的超声环境下超声分散4小时后放入密闭的反应容器中,于500W的微波环境中反应30min;取出加入二甲氧基乙烷,所加入的二甲氧基乙烷的体积是第一分散液中的初始的二甲氧基乙烷的体积的15%;继续于500W的微波环境中反应10min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的二甲氧基乙烷的体积比为1:10),得到反应物分散液,将反应物分散液于120W的超声环境中超声分散30分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将柠檬酸与粗产物进行混合,并加入氯化铁,混合均匀得到混合物,其中,粗产物与柠檬酸的质量比为1:5,氯化铁的质量占粗产物、柠檬酸、氯化铁的混合物的质量的3%;将该混合物加入N-甲基吡咯烷酮中,分散均匀得到混合物的浓度为0.5g/mL的第二分散液;
4、将第二分散液于120W的超声环境下分散2小时后放入密闭的反应容器中,于500W微波环境中反应1小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的N-甲基吡咯烷酮的体积比为1:15),然后于300W的超声环境下进行分散和剥离2小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:3混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:3混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为1:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
图2为本实施例1所制备得到的石墨烯量子点的荧光光谱图。由图2可看出,由本实施例1制备的得到的石墨烯量子点的荧光发射波长在435nm左右。
实施例2
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂中,均匀分散得到单层氧化石墨烯的浓度为6mg/mL的第一分散液,将草酸钠加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与草酸钠的质量比为1:8;
2、将该混合液于150W的超声环境下超声分散1小时后放入密闭的反应容器中,于700W的微波环境中反应20min;取出加入体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂,所加入的体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂的体积是第一分散液中的初始的体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂的体积的12%;继续于700W的微波环境中反应20min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂的体积比为1:20),得到反应物分散液,将反应物分散液于300W的超声环境中超声分散15分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将甲酸、抗坏血酸与粗产物进行混合,并加入氯化镁和氯化铜,混合均匀得到混合物,其中,粗产物、甲酸与抗坏血酸的质量比为1:4:4,氯化镁和氯化铜的质量比为1:1,氯化镁和氯化铜的质量之和占粗产物、甲酸、抗坏血酸、氯化镁和氯化铜的混合物的质量的2.5%;将该混合物加入体积比为1:1的三缩二乙二醇和N-甲基吡咯烷酮的混合溶剂中,分散均匀得到混合物的浓度为0.6g/mL的第二分散液;
4、将第二分散液于180W的超声环境下分散1.5小时后放入密闭的反应容器中,于550W微波环境中反应0.5小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:15),然后于180W的超声环境下进行分散和剥离3小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:2混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:2混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为2:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
图3为本实施例2所制备得到的石墨烯量子点的荧光光谱图。由图3可看出,由本实施例2制备的得到的石墨烯量子点的荧光发射波长在380nm左右。
实施例3
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于水中,均匀分散得到单层氧化石墨烯的浓度为3mg/mL的第一分散液,将抗坏血酸加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与抗坏血酸的质量比为1:4;
2、将该混合液于200W的超声环境下超声分散3小时后放入密闭的反应容器中,于650W的微波环境中反应8min;取出加入水,所加入的水的体积是第一分散液中的初始水的体积的10%;继续于650W的微波环境中反应8min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的水的体积比为1:10),得到反应物分散液,将反应物分散液于150W的超声环境中超声分散18分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将抗坏血酸与粗产物进行混合,并加入三氟化硼,混合均匀得到混合物,其中,粗产物与抗坏血酸的质量比为1:9,三氟化硼的质量占抗坏血酸、粗产物和三氟化硼的混合物的质量的1.5%;将该混合物加入水中,分散均匀得到混合物的浓度为0.2g/mL的第二分散液;
4、将第二分散液于250W的超声环境下分散1小时后放入密闭的反应容器中,于650W微波环境中反应0.5小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:10),然后于270W的超声环境下进行分散和剥离3小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:2混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:2混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为2:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
图4为本实施例3所制备得到的石墨烯量子点的荧光光谱图。由图4可看出,由本法制备的得到的石墨烯量子点的荧光发射波长在390nm左右。
实施例4
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于丙三醇中,均匀分散得到单层氧化石墨烯的浓度为5mg/mL的第一分散液,将葡萄糖酸钠加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与葡萄糖酸钠的质量比为1:6;
2、将该混合液于200W的超声环境下超声分散2小时后放入密闭的反应容器中,于600W的微波环境中反应10min;取出加入丙三醇,所加入的丙三醇的体积是第一分散液中的初始的丙三醇的体积的10%;继续于600W的微波环境中反应10min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的丙三醇的体积比为1:15),得到反应物分散液,将反应物分散液于180W的超声环境中超声分散20分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将柠檬酸与粗产物进行混合,并加入氯化锌,混合均匀得到混合物,其中,粗产物与柠檬酸的质量比为1:7,氯化锌的质量是柠檬酸、粗产物与氯化锌的混合物的质量的2%;将该混合物加入丙三醇中,分散均匀得到混合物的浓度为0.5g/mL的第二分散液;
4、将第二分散液于250W的超声环境下分散1小时后放入密闭的反应容器中,于700W微波环境中反应0.5小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:15),然后于180W的超声环境下进行分散和剥离3小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:2混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:2混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为2:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
图5为本实施例4所制备得到的石墨烯量子点的荧光光谱图。由图5可看出,由本法制备的得到的石墨烯量子点的荧光发射波长在410nm左右。
实施例5
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于二甲氧基乙烷中,均匀分散得到单层氧化石墨烯的浓度为2mg/mL的第一分散液,将草酸加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与草酸的质量比为1:3;
2、将该混合液于120W的超声环境下超声分散4小时后放入密闭的反应容器中,于500W的微波环境中反应30min;取出加入二甲氧基乙烷,所加入的二甲氧基乙烷的体积是第一分散液中的初始的二甲氧基乙烷的体积的15%;继续于500W的微波环境中反应10min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的二甲氧基乙烷的体积比为1:10),得到反应物分散液,将反应物分散液于280W的超声环境中超声分散5分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将葡萄糖与粗产物进行混合,并加入氯化铁,混合均匀得到混合物,其中,粗产物与葡萄糖的质量比为1:5,氯化铁的质量占葡萄糖、粗产物与氯化铁的混合物的质量的1%;将该混合物加入二甲氧基乙烷中,分散均匀得到混合物的浓度为0.1g/mL的第二分散液;
4、将第二分散液于120W的超声环境下分散2小时后放入密闭的反应容器中,于500W微波环境中反应1小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:20),然后于300W的超声环境下进行分散和剥离2小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:3混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:3混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为1:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
实施例6
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于质量浓度为10%的聚乙烯醇的水溶液中,均匀分散得到单层氧化石墨烯的浓度为10mg/mL的第一分散液,将质量比为1:1的柠檬酸和柠檬酸钠加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯的质量与柠檬酸和柠檬酸钠的质量之和的比值为1:10;
2、将该混合液于300W的超声环境下超声分散0.4小时后放入密闭的反应容器中,于800W的微波环境中反应5min;取出加入质量浓度为10%的聚乙烯醇的水溶液,所加入的质量浓度为10%的聚乙烯醇的水溶液的体积是第一分散液中的初始的质量浓度为10%的聚乙烯醇的水溶液的体积的10%;继续于800W的微波环境中反应5min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的质量浓度为10%的聚乙烯醇的水溶液的体积比为1:12),得到反应物分散液,将反应物分散液于200W的超声环境中超声分散30分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将葡萄糖与粗产物进行混合,并加入氯化铝,混合均匀得到混合物,其中,粗产物与葡萄糖的质量比为1:10,氯化铝的质量占葡萄糖、粗产物与氯化铝的混合物的质量的3%;将该混合物加入质量浓度为10%的聚乙烯醇的水溶液中,分散均匀得到混合物的浓度为1g/mL的第二分散液;
4、将第二分散液于300W的超声环境下分散0.5小时后放入密闭的反应容器中,于800W微波环境中反应0.2小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:15),然后于120W的超声环境下进行分散和剥离3小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:1混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:1混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为1:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
实施例7
制备石墨烯量子点
1、提供由改进Hummers的化学法制备的单层氧化石墨烯,将单层氧化石墨烯分散于三缩二乙二醇中,均匀分散得到单层氧化石墨烯的浓度为4mg/mL的第一分散液,将草酸钠加入第一分散液中,均匀分散得到混合液;其中,单层氧化石墨烯与草酸钠的质量比为1:7;
2、将该混合液于250W的超声环境下超声分散2.5小时后放入密闭的反应容器中,于550W的微波环境中反应25min;取出加入三缩二乙二醇,所加入的三缩二乙二醇的体积是第一分散液中的初始的三缩二乙二醇的体积的13%;继续于550W的微波环境中反应25min,反应结束后,待反应液冷却,向反应液中加入去离子水(去离子水与第一分散液中初始的三缩二乙二醇的体积比为1:18),得到反应物分散液,将反应物分散液于220W的超声环境中超声分散10分钟,然后进行抽滤,取滤液,得到石墨烯量子点的溶液,备用;取滤饼,得到粗产物;
3、将己二醛与粗产物进行混合,并加入氯化锂,混合均匀得到混合物,其中,粗产物与己二醛的质量比为1:6,氯化锂的质量是己二醛、粗产物和氯化锂的混合物的质量的2.5%;将该混合物加入三缩二乙二醇中,分散均匀得到混合物的浓度为0.3g/mL的第二分散液;
4、将第二分散液于150W的超声环境下分散1.8小时后放入密闭的反应容器中,于750W微波环境中反应0.4小时,加入去离子水将微波反应得到的反应液进行稀释后(去离子水与第二分散液中的二甲氧基乙烷的体积比为1:15),然后于250W的超声环境下进行分散和剥离2.5小时,得到石墨烯量子点的水溶液,将石墨烯量子点的水溶液和上述步骤2得到石墨烯的溶液进行柱层析,其中,柱层析的固定相为硅胶,第一相展开剂为二氯甲烷和甲醇按体积比为1:2混合的混合液,第二相展开剂为去离子水;进行柱层析依次得到粒径大小不同的石墨烯量子点的溶液;将溶剂为二氯甲烷和甲醇按体积比为1:2混合的混合液的石墨烯量子点的溶液进行真空下旋蒸蒸去溶剂,得到干燥的石墨烯量子点粉末;将溶剂为去离子水的石墨烯量子点的溶液通过二氯甲烷和甲醇按体积比为2:1的混合溶剂进行萃取,再旋蒸蒸去溶剂,获得干燥的石墨烯量子点粉末。
以上所述实施例仅表达了本发明的几种实施方式,其描述较为具体和详细,但并不能因此而理解为对本发明专利范围的限制。应当指出的是,对于本领域的普通技术人员来说,在不脱离本发明构思的前提下,还可以做出若干变形和改进,这些都属于本发明的保护范围。因此,本发明专利的保护范围应以所附权利要求为准。

Claims (15)

  1. 一种石墨烯量子点的大规模制备方法,其特征在于,包括如下步骤:
    将氧化石墨烯加入第一溶剂中,均匀分散得到第一分散液,将还原剂加入所述第一分散液中,均匀分散得到混合液;
    将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟,冷却后进行固液分离,取固体,得到粗产物;
    将还原性多羟基醛及有机酸中的一种与所述粗产物进行混合,加入路易斯酸,混合均匀得到混合物,将所述混合物加入第二溶剂中,均匀分散得到第二分散液;及
    将所述第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时,然后于120瓦~300瓦的超声环境下剥离2小时~3小时,分离纯化后得到所述石墨烯量子点。
  2. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟的步骤之前,包括超声搅拌的步骤,所述超声搅拌的步骤具体为:将所述混合液于120瓦~300瓦的超声环境下搅拌0.5小时~4小时。
  3. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,将所述第二分散液于500瓦~800瓦微波环境中反应0.2小时~1小时的步骤之前,还包括超声分散的步骤,所述超声分散的步骤具体为:将所述第二分散液于120瓦~300瓦的超声环境中分散0.5小时~2小时。
  4. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述第一溶剂和第二溶剂均选自水、二甲氧基乙烷、聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。
  5. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述第一分散液中,所述氧化石墨烯的浓度为2毫克/毫升~10毫克/毫升。
  6. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述还原剂选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸、草酸、柠檬酸钠、葡萄糖酸钠、甲酸钠、抗坏血酸钠及草酸钠中的至少一种。
  7. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述氧化石墨烯与所述还原剂的质量比为1:3~10。
  8. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述将所述混合液于500瓦~800瓦的微波环境中反应10分钟~60分钟的操作具体为:将所述混合液于500瓦~800瓦的微波环境中反应5分钟~30分钟,取出补加所述第一溶剂后,继续于500瓦~800瓦的微波环境中反应5分钟~30分钟;其中,所补加的第一溶剂的体积为所述第一溶剂的初始体积的10%~15%。
  9. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述粗产物与所述还原性多羟基醛及有机酸中的一种的质量比为1:5~10。
  10. 根据权利要求1或9所述的石墨烯量子点的大规模制备方法,其特征在于,所述还原性多羟基醛为葡萄糖或己二醛。
  11. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述路易斯酸选自氯化铁、氯化铝、氯化锌、三氟化硼、氯化镁、氯化铜及氯化锂中的至少一种。
  12. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述有机酸选自柠檬酸、葡萄糖酸、甲酸、抗坏血酸及草酸中的至少一种。
  13. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述第二分散液中,所述混合物的浓度为0.1克/毫升~1克/毫升。
  14. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述路易斯酸的质量占所述混合物的质量的1%~3%。
  15. 根据权利要求1所述的石墨烯量子点的大规模制备方法,其特征在于,所述分离纯化后得到所述石墨烯量子点的步骤具体为:将所述于120瓦~300瓦的超声环境下剥离2小时~3小时得到的反应产物进行柱层析分离,然后真空旋蒸除去溶剂,得到所述石墨烯量子点;其中,所述柱层析的固定相为硅胶或聚丙烯酰胺,第一相展开剂为二氯甲烷和甲醇按体积比1:1~3进行混合的混合液,第二相展开剂为去离子水。
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