WO2016045045A1 - Method for preparing graphene quantum dots - Google Patents

Method for preparing graphene quantum dots Download PDF

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WO2016045045A1
WO2016045045A1 PCT/CN2014/087419 CN2014087419W WO2016045045A1 WO 2016045045 A1 WO2016045045 A1 WO 2016045045A1 CN 2014087419 W CN2014087419 W CN 2014087419W WO 2016045045 A1 WO2016045045 A1 WO 2016045045A1
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graphene quantum
quantum dots
solution
graphene
preparing
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PCT/CN2014/087419
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French (fr)
Chinese (zh)
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张麟德
张明东
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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/CN2014/087419 priority Critical patent/WO2016045045A1/en
Publication of WO2016045045A1 publication Critical patent/WO2016045045A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/02—Oxides; Hydroxides

Definitions

  • the invention relates to the technical field of graphene quantum dots, in particular to a method for preparing graphene quantum dots.
  • top-down method of cracking graphene to obtain graphene quantum dots including secondary oxidation, electron beam or ion beam etching, hydrothermal cracking or solvothermal cracking, and micro-cutting of carbon materials Method
  • bottom-up method is mainly organic synthesis method starting from small organic molecules.
  • the size distribution of graphene quantum dots is too wide, which leads to various non-radiative transitions between graphene quantum dots to reduce energy, which makes the resulting graphene quantum dots have low quantum yield and wide fluorescence wavelength, which loses its application significance. .
  • a method for preparing graphene quantum dots comprising the following steps:
  • zinc oxide having a hexagonal crystal structure as a seed crystal nucleus, wherein the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm;
  • the colloidal solution is hydrothermally reacted at 160 ° C to 300 ° C for 0.5 h to 2 h to obtain a suspension containing graphene quantum dots;
  • Adding an acid to the suspension containing the graphene quantum dots causes the suspension containing the graphene quantum dots to be clarified, and filtering the clarified suspension containing the graphene quantum dots to obtain a filtrate Adjusting the pH of the filtrate to 7-8 and stirring, then filtering, and discarding the precipitate to obtain a solution containing graphene quantum dots;
  • the solution containing the graphene quantum dots is extracted, and then the extractant is removed by evaporation to obtain graphene quantum dots.
  • the zinc oxide having a hexagonal crystal structure is prepared as follows:
  • the first solution and the second solution are mixed, stirred for 2 h to 3 h, and the precipitate is taken by centrifugation, and the precipitate is washed to obtain the zinc oxide having a hexagonal crystal structure.
  • the zinc salt in the first solution, has a mass percentage concentration of 5% to 25%, and the protective agent has a mass percentage concentration of 0.2% to 1%.
  • the protective agent is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide, and ten At least one of octadecyltrimethylammonium bromide.
  • the volume ratio of ammonia to ethanol is 1:5-8.
  • the volume ratio of the first solution to the second solution is from 1 to 2:1.
  • the concentration of the single-layer graphene oxide is 2 mg/mL to 10 mg/mL.
  • the stabilizer is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide, and ten At least one of octadecyltrimethylammonium bromide.
  • the stabilizer has a mass percent concentration in the colloidal solution of from 0.1% to 3%.
  • the solvent is selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol having a 10% by weight concentration, glycerol, triethylene glycol, and N-methylpyrrolidone. At least one of them.
  • the mass ratio of the single-layer graphene oxide to the zinc oxide having a hexagonal crystal structure is from 1 to 10:1.
  • the above method for preparing graphene quantum dots uses zinc oxide having a hexagonal crystal structure as a seed crystal nucleus for inducing growth of graphene quantum dots, and zinc oxide having a hexagonal crystal structure and graphene oxide belong to the same kind of lattice crystal, and as an oxide
  • the oxygen atom on the exposed crystal face of the zinc oxide can form a hydrogen bond with the hydroxyl group on the graphene oxide to cause the graphene oxide to be adsorbed on the exposed crystal face of the zinc oxide, thereby inducing the graphene through the zinc oxide as the seed crystal nucleus.
  • FIG. 1 is a flow chart showing a method of preparing graphene quantum dots according to an embodiment
  • Example 2 is an atomic force microscope (AFM) diagram of the graphene quantum dots of Example 1;
  • Example 3 is another atomic force microscope (AFM) diagram of the graphene quantum dots of Example 1.
  • a method for preparing a graphene quantum dot includes the following steps 110 to 150 .
  • Step 110 Providing zinc oxide having a hexagonal crystal structure as a seed crystal nucleus, and the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm.
  • the [1000] and [1111] crystal faces of zinc oxide having a hexagonal crystal structure are exposed crystal faces.
  • Graphene and graphene oxide are more likely to grow on the [1000] and [1111] crystal faces of zinc oxide having a hexagonal crystal structure.
  • Zinc oxide having a hexagonal crystal structure is used as a seed nucleus to induce graphene quantum dot growth, and the size of the graphene quantum dot can be indirectly controlled by controlling the particle size of zinc oxide having a hexagonal crystal structure.
  • the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm.
  • the zinc oxide having a hexagonal crystal structure is spherical, hexagonal or rod-shaped.
  • the particle diameter of 5 nm to 30 nm means that the diameter of the zinc oxide is 5 nm to 30 nm; when the zinc oxide is hexagonal, the particle diameter of 5 nm to 30 nm means the farthest angle of the zinc oxide.
  • the distance is 5 nm to 30 nm; when the zinc oxide is in the form of a rod, the particle diameter of 5 nm to 30 nm means that the length of the zinc oxide is 5 nm to 30 nm.
  • zinc oxide having a hexagonal crystal structure is prepared as follows.
  • the method of preparing zinc oxide having a hexagonal crystal structure as follows includes steps 210 to 230.
  • Step 210 Dissolve the zinc salt in an alcohol solvent and heat it at 50 ° C ⁇ 60 ° C water bath for 0.5 h ⁇ 4 h, then adding a protective agent to obtain a first solution.
  • the zinc salt is preferably zinc acetate (Zn(CH 3 COO) 2 ) or zinc chloride (ZnCl 2 ).
  • the alcohol solvent is at least one selected from the group consisting of methanol, ethanol, isopropanol, tert-butanol, isoamyl alcohol, cyclohexanol, ethylene glycol, glycerin, and hexanediol.
  • the alcohol solvent is at least one selected from the group consisting of ethanol, isopropanol, and ethylene glycol.
  • the role of the protective agent is to promote the dispersion of the zinc salt.
  • the protective agent is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide and octadecyltrimethylammonium bromide. At least one of them.
  • the protective agent is selected from at least one of polymethylpyrrolidone, hydroxypropylcellulose, carboxymethylcellulose, and tetrabutylammonium bromide.
  • the mass percentage concentration of the zinc salt is 5% to 25%, and the mass percentage concentration of the protective agent is 0.2% to 1%.
  • Step 220 preparing a mixed solution of ammonia water and ethanol, and adding sodium hydroxide or potassium hydroxide to obtain a second solution, wherein the concentration of sodium hydroxide or potassium hydroxide in the second solution is 0.1 mg/L to 0.5 mg. /L.
  • the volume ratio of ammonia water to ethanol is 1:5-8.
  • the mass percentage of ammonia water is 25% to 28%
  • ethanol is anhydrous ethanol.
  • Sodium hydroxide or potassium hydroxide is added to adjust the pH of the mixed solution of ammonia water and ethanol.
  • concentration of sodium hydroxide or potassium hydroxide in the second solution of aqueous ammonia and ethanol is from 0.1 mg/mL to 0.5 mg/mL.
  • Step 230 Mixing the first solution and the second solution, stirring for 2 h to 3 h, centrifuging to take a precipitate, and washing the precipitate to obtain zinc oxide having a hexagonal crystal structure.
  • the first solution and the second solution are mixed under stirring at a rate of 30 rpm to 60 rpm.
  • the volume ratio of the first solution to the second solution is from 1 to 2:1.
  • the rate of centrifugation is preferably from 3000 rpm to 4000 rpm, and the centrifugation time is from 5 min to 30 min.
  • the zinc oxide having a hexagonal crystal structure may be a commercially available zinc oxide having a hexagonal crystal structure.
  • Step 120 adding a single layer of graphene oxide to a solvent to prepare a dispersion of graphene oxide, adding zinc oxide having a hexagonal crystal structure to the dispersion of graphene oxide, adding a stabilizer, and uniformly dispersing to obtain a colloidal solution.
  • the solvent is selected from at least one selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol having a 10% by mass concentration, glycerin, triethylene glycol, and N-methylpyrrolidone.
  • the above solvent has a high boiling point, contributes to the formation of graphene quantum dots at a low pressure, and prevents carbon dots formed by pyrolysis of the solvent itself from entering the system as impurities.
  • the solvent is at least one selected from the group consisting of glycerol, N-methylpyrrolidone, and an aqueous solution of polyvinyl alcohol having a 10% by mass concentration.
  • the mass ratio of the single-layer graphene oxide to the zinc oxide having the hexagonal crystal structure is from 1 to 10:1.
  • the concentration of the single-layer graphene oxide is 2 mg/mL to 10 mg/mL.
  • the stabilizer is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide and octadecyltrimethylammonium bromide. At least one of them.
  • the stabilizer is selected from at least one of polymethylpyrrolidone and tetrabutylammonium bromide.
  • Stabilizers are used to promote the dispersion of zinc oxide having a hexagonal crystal structure in the system.
  • the mass percent concentration of the stabilizer in the colloidal solution is from 0.1% to 3%.
  • the dispersion is stirred and dispersed under ultrasonic waves.
  • the ultrasonic power is 120w ⁇ 300w
  • the stirring and dispersing time is 1h ⁇ 2h.
  • Step 130 hydrothermal reaction of the colloidal solution at 160 ° C to 300 ° C for 0.5 h to 2 h to obtain a suspension containing graphene quantum dots.
  • the colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 160 ° C ⁇ 300 ° C for 0.5 h ⁇ 2 h.
  • the single layer of graphene oxide was cracked to form graphene quantum dots.
  • Step 140 adding an acid to a suspension containing graphene quantum dots to clarify a suspension containing graphene quantum dots, filtering a clear suspension containing graphene quantum dots, taking a filtrate, and separating the filtrate.
  • the pH was adjusted to 7-8 and stirred, then filtered, and the precipitate was discarded to obtain a solution containing graphene quantum dots.
  • An acid is added to the suspension containing graphene quantum dots to adjust the pH of the suspension containing graphene quantum dots to 2 to 3.
  • the pH is 2 to 3
  • the suspension containing graphene quantum dots becomes clear.
  • the above acid for adjusting the pH is hydrochloric acid having a pH of 1.
  • the clarified suspension containing graphene quantum dots was filtered to remove graphene sheets which were not cracked after the hydrothermal reaction but were reduced at a high temperature.
  • the pH of the filtrate was adjusted to 7-8 using ammonia water having a mass percentage concentration of 10% to 25%.
  • the pH of the filtrate was adjusted to 7 to 8 and stirred to precipitate zinc hydroxide, and zinc hydroxide was removed by filtration to obtain a solution containing graphene quantum dots.
  • Step 150 extracting a solution containing graphene quantum dots, and then removing the extractant by evaporation to obtain graphene quantum dots.
  • the extracting agent is selected from at least methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, chloroform, dichloromethane, carbon tetrachloride, diethyl ether, toluene, benzene, cyclohexane, petroleum ether, hexane and pentane.
  • the extractant is selected from at least one of methanol, ethyl acetate, ethanol, acetonitrile, chloroform, dichloromethane, and petroleum ether.
  • the volume ratio of the solution containing the graphene quantum dots to the extractant is 1:1 to 5.
  • the extractant containing graphene quantum dots is subjected to rotary evaporation to remove the extractant to obtain graphene quantum dots.
  • the size of the graphene quantum dots is 3 nm to 50 nm, and the size distribution is narrow, and the fluorescent color is adjustable.
  • Graphene quantum dots can be obtained from a solution containing graphene quantum dots by simple extraction without using a chromatographic method for purification as in the conventional method for preparing graphene quantum dots, and the process is relatively simple.
  • the above method for preparing graphene quantum dots uses zinc oxide having a hexagonal crystal structure as a seed crystal nucleus for inducing growth of graphene quantum dots, and zinc oxide having a hexagonal crystal structure and graphene oxide belong to the same kind of lattice crystal, and as an oxide
  • the oxygen atom on the exposed crystal face of the zinc oxide can form a hydrogen bond with the hydroxyl group on the graphene oxide to cause the graphene oxide to be adsorbed on the exposed crystal face of the zinc oxide, thereby inducing the graphene through the zinc oxide as the seed crystal nucleus.
  • the size of the graphene quantum dots prepared by the above method for preparing graphene quantum dots is equivalent to the particle size of zinc oxide having a hexagonal crystal structure, and the particle size of zinc oxide having a hexagonal crystal structure can be controlled.
  • the separation technique separates graphene quantum dots of different sizes one by one.
  • the graphene quantum dots are prepared by using the above-mentioned method for preparing graphene quantum dots.
  • the size and fluorescent color of the graphene quantum dots are adjustable, the size distribution is narrow, and the quantum yield is high, so that it can be effectively obtained in the fields of LED and biological imaging. Good application.
  • the above-described method for preparing graphene quantum dots is simpler than the conventional bottom-up method, and it is not necessary to use a silica gel chromatography method as in the conventional bottom-up method. It is confirmed by standard characterization method, avoiding too cumbersome operations, and is conducive to industrial production and expansion of applications.
  • the first solution and the second solution were mixed at a volume ratio of 1:1, stirred at a rate of 60 rpm for 2 hours, and then centrifuged at a rate of 3000 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure, and the zinc oxide having a hexagonal crystal structure was spherical and had a particle diameter of 7.5 nm.
  • the colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermally reacted at 160 ° C for 2 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
  • the first solution and the second solution were mixed at a volume ratio of 2:1, stirred at a rate of 30 rpm for 3 hours, and then centrifuged at a rate of 4000 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure.
  • the zinc oxide having a hexagonal crystal structure was hexagonal and had a particle diameter of 15 nm.
  • the colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 300 ° C for 0.5 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
  • the mass percentage concentration of zinc chloride is 20%
  • the mass percentage concentration of hydroxymethyl cellulose is 0.4%
  • the mass percentage concentration of hydroxyethyl cellulose is 0.4%.
  • a mixture of ammonia water and ethanol was prepared by mixing a mass percentage of 28% ammonia water with absolute ethanol at a volume ratio of 1:6, and potassium hydroxide was added to obtain a second solution.
  • the concentration of potassium hydroxide in the second solution was 0.3 mg/L.
  • the first solution and the second solution were mixed at a volume ratio of 1.5:1, stirred at a rate of 50 rpm for 2.5 h, and then centrifuged at a rate of 3500 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure.
  • the zinc oxide having a hexagonal crystal structure was rod-shaped and had a particle diameter of 23 nm.
  • the mass ratio of the single-layer graphene oxide to the zinc oxide having the hexagonal phase structure is 8:1
  • the mass concentration of the polymethylpyrrolidone in the colloidal solution is 0.4%
  • the tetrabutylammonium bromide is in the colloidal solution.
  • the mass percentage concentration is 0.4%.
  • the colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 250 ° C for 1 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
  • the first solution and the second solution were mixed at a volume ratio of 2:1, stirred at a rate of 55 rpm for 3 hours, and then centrifuged at a rate of 3800 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure.
  • the zinc oxide having a hexagonal crystal structure was spherical and had a particle diameter of 28 nm.
  • the colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermally reacted at 200 ° C for 1.5 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
  • the graphene quantum dot solution is extracted by using a mixed solvent of dichloromethane and petroleum ether in a volume ratio of 1:1 as an extractant.
  • the volume ratio of the solution containing the graphene quantum dots to the extracting agent is 1:4.

Abstract

The present invention relates to a method for preparing graphene quantum dots, comprising the steps of providing zinc oxide having a hexagonal crystal structure and a particle size of 5 nm - 30 nm as a seed crystal nucleus; adding a single layer of graphene oxide to a solvent, and making up a liquid dispersion of graphene oxide, adding the zinc oxide having the hexagonal crystal structure, then adding a stabilizer, and dispersing evenly to obtain a colloid solution; subjecting the colloid solution to a hydrothermal reaction at 160°C - 300°C for 0.5 h - 2 h, to obtain a turbid liquid containing graphene quantum dots; adding an acid to the turbid liquid containing graphene quantum dots to clarify the turbid liquid containing graphene quantum dots, filtering, adjusting the pH of the filtrate to 7 - 8 and stirring, then filtering to obtain a solution containing graphene quantum dots; and subjecting the solution containing graphene quantum dots to extraction, then removing the extracting agent by evaporation, to obtain graphene quantum dots. The process of the method is relatively simple, and can prepare graphene quantum dots with a relatively narrow size distribution.

Description

石墨烯量子点的制备方法Method for preparing graphene quantum dots
【技术领域】[Technical Field]
本发明涉及石墨烯量子点技术领域，特别是涉及一种石墨烯量子点的制备方法。 The invention relates to the technical field of graphene quantum dots, in particular to a method for preparing graphene quantum dots.
【背景技术】【Background technique】
目前，在石墨烯量子点的研究中，主要采用的制备方法可以分成自上而下和自下而上的两种方法。自上而下的方法，即对石墨烯进行裂解得到石墨烯量子点，包括二次氧化法、电子束或离子束蚀刻法、水热裂解法或溶剂热裂解法以及对碳材料进行微观切割的方法；而自下而上的方法主要是从有机小分子出发的有机合成法。其中，自上而下的方法中始终存在着一个问题，就是没有办法控制石墨烯量子点的尺寸分布，而自下而上的方法又过于繁琐，不利于工业生产与扩大应用。石墨烯量子点的尺寸分布过广，会导致石墨烯量子点间存在各种非辐射跃迁从而降低能量，使得到的石墨烯量子点其量子产率低，且荧光波长变宽，失去其应用意义。At present, in the study of graphene quantum dots, the main preparation methods can be divided into two methods: top-down and bottom-up. Top-down method of cracking graphene to obtain graphene quantum dots, including secondary oxidation, electron beam or ion beam etching, hydrothermal cracking or solvothermal cracking, and micro-cutting of carbon materials Method; the bottom-up method is mainly organic synthesis method starting from small organic molecules. Among them, there is always a problem in the top-down method, that is, there is no way to control the size distribution of graphene quantum dots, and the bottom-up method is too cumbersome, which is not conducive to industrial production and expansion of applications. The size distribution of graphene quantum dots is too wide, which leads to various non-radiative transitions between graphene quantum dots to reduce energy, which makes the resulting graphene quantum dots have low quantum yield and wide fluorescence wavelength, which loses its application significance. .
【发明内容】 [Summary of the Invention]
基于此，有必要提供一种工艺较为简单的石墨烯量子点的制备方法，以制备尺寸分布较窄的石墨烯量子点。Based on this, it is necessary to provide a preparation method of graphene quantum dots with relatively simple process to prepare graphene quantum dots with narrow size distribution.
一种石墨烯量子点的制备方法，包括如下步骤：A method for preparing graphene quantum dots, comprising the following steps:
提供具有六方晶体结构的氧化锌作为种子晶核，所述具有六方晶体结构的氧化锌的粒径为5nm~30nm；Providing zinc oxide having a hexagonal crystal structure as a seed crystal nucleus, wherein the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm;
将单层氧化石墨烯加入溶剂中，配制氧化石墨烯的分散液，向所述氧化石墨烯的分散液中加入所述具有六方晶体结构的氧化锌，然后加入稳定剂，分散均匀得到胶体溶液；Adding a single layer of graphene oxide to a solvent to prepare a dispersion of graphene oxide, adding the zinc oxide having a hexagonal crystal structure to the dispersion of graphene oxide, adding a stabilizer, and uniformly dispersing to obtain a colloidal solution;
将所述胶体溶液于160℃~300℃下进行水热反应0.5h~2h，得到含有石墨烯量子点的悬浊液；The colloidal solution is hydrothermally reacted at 160 ° C to 300 ° C for 0.5 h to 2 h to obtain a suspension containing graphene quantum dots;
向所述含有石墨烯量子点的悬浊液中加入酸使所述含有石墨烯量子点的悬浊液变澄清，将变澄清的所述含有石墨烯量子点的悬浊液进行过滤，取滤液，将所述滤液的pH值调节为7~8并搅拌，然后过滤，弃沉淀，得到含有石墨烯量子点的溶液；及Adding an acid to the suspension containing the graphene quantum dots causes the suspension containing the graphene quantum dots to be clarified, and filtering the clarified suspension containing the graphene quantum dots to obtain a filtrate Adjusting the pH of the filtrate to 7-8 and stirring, then filtering, and discarding the precipitate to obtain a solution containing graphene quantum dots;
将所述含有石墨烯量子点的溶液进行萃取，然后蒸发除去萃取剂，得到石墨烯量子点。The solution containing the graphene quantum dots is extracted, and then the extractant is removed by evaporation to obtain graphene quantum dots.
在其中一个实施例中，所述具有六方晶体结构的氧化锌按如下方法制备：In one embodiment, the zinc oxide having a hexagonal crystal structure is prepared as follows:
将锌盐溶于醇类溶剂中，于50℃~60℃水浴下加热0.5h~4h，然后加入保护剂，得到第一溶液；Dissolving the zinc salt in an alcohol solvent, heating in a water bath at 50 ° C ~ 60 ° C for 0.5 h ~ 4 h, and then adding a protective agent to obtain a first solution;
配制氨水和乙醇的混合溶液，并加入氢氧化钠或氢氧化钾，得到第二溶液，其中，所述氢氧化钠或氢氧化钾在所述第二溶液中的浓度为0.1mg/L~0.5mg/L；Preparing a mixed solution of ammonia water and ethanol, and adding sodium hydroxide or potassium hydroxide to obtain a second solution, wherein the concentration of the sodium hydroxide or potassium hydroxide in the second solution is 0.1 mg/L to 0.5 Mg/L;
将所述第一溶液和第二溶液混合，搅拌2h~3h，离心取沉淀，洗涤所述沉淀得到所述具有六方晶体结构的氧化锌。The first solution and the second solution are mixed, stirred for 2 h to 3 h, and the precipitate is taken by centrifugation, and the precipitate is washed to obtain the zinc oxide having a hexagonal crystal structure.
在其中一个实施例中，所述第一溶液中，所述锌盐的质量百分比浓度为5%~25%，所述保护剂的质量百分比浓度为0.2%~1%。In one embodiment, in the first solution, the zinc salt has a mass percentage concentration of 5% to 25%, and the protective agent has a mass percentage concentration of 0.2% to 1%.
在其中一个实施例中，所述保护剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。In one embodiment, the protective agent is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide, and ten At least one of octadecyltrimethylammonium bromide.
在其中一个实施例中，所述氨水和乙醇的体积比为1:5~8。In one embodiment, the volume ratio of ammonia to ethanol is 1:5-8.
在其中一个实施例中，所述第一溶液和第二溶液的体积比为1~2:1。In one embodiment, the volume ratio of the first solution to the second solution is from 1 to 2:1.
在其中一个实施例中，所述氧化石墨烯的分散液中，所述单层氧化石墨烯的浓度为2mg/mL~10mg/mL。In one embodiment, in the dispersion of graphene oxide, the concentration of the single-layer graphene oxide is 2 mg/mL to 10 mg/mL.
在其中一个实施例中，所述稳定剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。In one embodiment, the stabilizer is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide, and ten At least one of octadecyltrimethylammonium bromide.
在其中一个实施例中，所述稳定剂在所述胶体溶液中的中的质量百分比浓度为0.1%~3%。In one embodiment, the stabilizer has a mass percent concentration in the colloidal solution of from 0.1% to 3%.
在其中一个实施例中，所述溶剂选自水、二甲氧基乙烷、质量百分比浓度为10%的聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。In one embodiment, the solvent is selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol having a 10% by weight concentration, glycerol, triethylene glycol, and N-methylpyrrolidone. At least one of them.
在其中一个实施例中，所述单层氧化石墨烯与具有六方晶体结构的氧化锌的质量比为1~10:1。In one embodiment, the mass ratio of the single-layer graphene oxide to the zinc oxide having a hexagonal crystal structure is from 1 to 10:1.
上述石墨烯量子点的制备方法使用具有六方晶体结构的氧化锌作为诱导石墨烯量子点生长的种子晶核，具有六方晶体结构的氧化锌与氧化石墨烯属于同种格子的晶体，且作为氧化物，氧化锌的暴露晶面上的氧原子能与氧化石墨烯上的羟基形成氢键而使氧化石墨烯被吸附在氧化锌的暴露晶面上，从而可以通过氧化锌作为种子晶核来诱导石墨烯量子点的生长并通过控制氧化锌的尺寸来间接控制吸附在氧化锌表面的氧化石墨烯的量和尺寸；并且，在随后的水热反应中，使氧化锌表面的氧化石墨烯保持吸附的同时被裂解，形成石墨烯量子点，也就间接的控制了石墨烯量子点的尺寸大小与分布情况，从而获得尺寸分布较窄的石墨烯量子点。The above method for preparing graphene quantum dots uses zinc oxide having a hexagonal crystal structure as a seed crystal nucleus for inducing growth of graphene quantum dots, and zinc oxide having a hexagonal crystal structure and graphene oxide belong to the same kind of lattice crystal, and as an oxide The oxygen atom on the exposed crystal face of the zinc oxide can form a hydrogen bond with the hydroxyl group on the graphene oxide to cause the graphene oxide to be adsorbed on the exposed crystal face of the zinc oxide, thereby inducing the graphene through the zinc oxide as the seed crystal nucleus. Growth of quantum dots and indirectly controlling the amount and size of graphene oxide adsorbed on the surface of zinc oxide by controlling the size of zinc oxide; and, in the subsequent hydrothermal reaction, while maintaining the adsorption of graphene oxide on the surface of zinc oxide It is cleaved to form graphene quantum dots, which indirectly controls the size and distribution of graphene quantum dots, thereby obtaining graphene quantum dots with narrow size distribution.
并且，上述石墨烯量子点的制备方法相对于传统的自下而上的方法，工艺较为简单。Moreover, the above-described method for preparing graphene quantum dots is simpler than the conventional bottom-up method.
【附图说明】[Description of the Drawings]
图1为一实施方式的石墨烯量子点的制备方法的流程图；1 is a flow chart showing a method of preparing graphene quantum dots according to an embodiment;
图2为实施例1的石墨烯量子点的原子力显微镜（AFM）图；2 is an atomic force microscope (AFM) diagram of the graphene quantum dots of Example 1;
图3为实施例1的石墨烯量子点的另一原子力显微镜（AFM）图。3 is another atomic force microscope (AFM) diagram of the graphene quantum dots of Example 1.
【具体实施方式】 【detailed description】
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。The above described objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims. Numerous specific details are set forth in the description below in order to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention, and thus the invention is not limited by the specific embodiments disclosed below.
请参阅图1，一实施方式的石墨烯量子点的制备方法，包括如下步骤110至步骤150。Referring to FIG. 1 , a method for preparing a graphene quantum dot according to an embodiment includes the following steps 110 to 150 .
步骤110：提供具有六方晶体结构的氧化锌作为种子晶核，具有六方晶体结构的氧化锌的粒径为5nm~30nm。Step 110: Providing zinc oxide having a hexagonal crystal structure as a seed crystal nucleus, and the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm.
具有六方晶体结构的氧化锌的[1000]和[1111]晶面为暴露的晶面。石墨烯及氧化石墨烯较易生长于具有六方晶体结构的氧化锌的[1000]和[1111]晶面上。将具有六方晶体结构的氧化锌作为种子晶核来诱导石墨烯量子点生长，通过控制具有六方晶相结构的氧化锌的粒径能够间接控制石墨烯量子点的尺寸。The [1000] and [1111] crystal faces of zinc oxide having a hexagonal crystal structure are exposed crystal faces. Graphene and graphene oxide are more likely to grow on the [1000] and [1111] crystal faces of zinc oxide having a hexagonal crystal structure. Zinc oxide having a hexagonal crystal structure is used as a seed nucleus to induce graphene quantum dot growth, and the size of the graphene quantum dot can be indirectly controlled by controlling the particle size of zinc oxide having a hexagonal crystal structure.
具有六方晶体结构的氧化锌的粒径为5nm~30nm。具有六方晶体结构的氧化锌为球形、六角形或棒状。当氧化锌为球形时，粒径为5nm~30nm是指氧化锌的直径为5nm~30nm；当氧化锌为六角形时，粒径为5nm~30nm是指氧化锌的最远的两个角的距离为5nm~30nm；当氧化锌为棒状时，粒径为5nm~30nm是指氧化锌的长度为5nm~30nm。The zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm. The zinc oxide having a hexagonal crystal structure is spherical, hexagonal or rod-shaped. When the zinc oxide is spherical, the particle diameter of 5 nm to 30 nm means that the diameter of the zinc oxide is 5 nm to 30 nm; when the zinc oxide is hexagonal, the particle diameter of 5 nm to 30 nm means the farthest angle of the zinc oxide. The distance is 5 nm to 30 nm; when the zinc oxide is in the form of a rod, the particle diameter of 5 nm to 30 nm means that the length of the zinc oxide is 5 nm to 30 nm.
优选地，具有六方晶体结构的氧化锌按如下方法制备。如下制备具有六方晶体结构的氧化锌的方法包括步骤210至步骤230。Preferably, zinc oxide having a hexagonal crystal structure is prepared as follows. The method of preparing zinc oxide having a hexagonal crystal structure as follows includes steps 210 to 230.
步骤210：将锌盐溶于醇类溶剂中，于50℃~60℃水浴下加热0.5 h~4 h，然后加入保护剂，得到第一溶液。Step 210: Dissolve the zinc salt in an alcohol solvent and heat it at 50 ° C ~ 60 ° C water bath for 0.5 h ~ 4 h, then adding a protective agent to obtain a first solution.
锌盐优选为醋酸锌（Zn(CH3COO)2）或氯化锌（ZnCl2）。The zinc salt is preferably zinc acetate (Zn(CH 3 COO) 2 ) or zinc chloride (ZnCl 2 ).
醇类溶剂选自甲醇、乙醇、异丙醇、叔丁醇、异戊醇、环己醇、乙二醇、丙三醇及己二醇中的至少一种。优选地，醇类溶剂选自乙醇、异丙醇及乙二醇中的至少一种。The alcohol solvent is at least one selected from the group consisting of methanol, ethanol, isopropanol, tert-butanol, isoamyl alcohol, cyclohexanol, ethylene glycol, glycerin, and hexanediol. Preferably, the alcohol solvent is at least one selected from the group consisting of ethanol, isopropanol, and ethylene glycol.
保护剂的作用是促进锌盐的分散。保护剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。优选地，保护剂选自聚甲基吡咯烷酮、羟丙基纤维素、羧甲基纤维素及四丁基溴化铵中的至少一种。The role of the protective agent is to promote the dispersion of the zinc salt. The protective agent is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide and octadecyltrimethylammonium bromide. At least one of them. Preferably, the protective agent is selected from at least one of polymethylpyrrolidone, hydroxypropylcellulose, carboxymethylcellulose, and tetrabutylammonium bromide.
优选地，第一溶液中，锌盐的质量百分比浓度为5%~25%，保护剂的质量百分比浓度为0.2%~1%。Preferably, in the first solution, the mass percentage concentration of the zinc salt is 5% to 25%, and the mass percentage concentration of the protective agent is 0.2% to 1%.
步骤220：配制氨水和乙醇的混合溶液，并加入氢氧化钠或氢氧化钾，得到第二溶液，其中，氢氧化钠或氢氧化钾在第二溶液中的浓度为0.1mg/L~0.5mg/L。Step 220: preparing a mixed solution of ammonia water and ethanol, and adding sodium hydroxide or potassium hydroxide to obtain a second solution, wherein the concentration of sodium hydroxide or potassium hydroxide in the second solution is 0.1 mg/L to 0.5 mg. /L.
氨水和乙醇的混合溶液中，氨水和乙醇的体积比为1:5~8。其中，氨水的质量百分比浓度为25%~28%，乙醇为无水乙醇。In the mixed solution of ammonia water and ethanol, the volume ratio of ammonia water to ethanol is 1:5-8. Among them, the mass percentage of ammonia water is 25% to 28%, and ethanol is anhydrous ethanol.
加入氢氧化钠或氢氧化钾以调节氨水和乙醇的混合溶液的pH值。优选地，氢氧化钠或氢氧化钾在氨水和乙醇的第二溶液中的浓度为0.1mg/mL~0.5mg/mL。Sodium hydroxide or potassium hydroxide is added to adjust the pH of the mixed solution of ammonia water and ethanol. Preferably, the concentration of sodium hydroxide or potassium hydroxide in the second solution of aqueous ammonia and ethanol is from 0.1 mg/mL to 0.5 mg/mL.
步骤230：将第一溶液和第二溶液混合，搅拌2h~3h，离心取沉淀，洗涤沉淀得到具有六方晶体结构的氧化锌。Step 230: Mixing the first solution and the second solution, stirring for 2 h to 3 h, centrifuging to take a precipitate, and washing the precipitate to obtain zinc oxide having a hexagonal crystal structure.
将第一溶液和第二溶液于搅拌下进行混合，搅拌的速率为30rpm~60rpm。The first solution and the second solution are mixed under stirring at a rate of 30 rpm to 60 rpm.
第一溶液和第二溶液的体积比为1~2:1。离心的速率优选为3000rpm~4000rpm，离心的时间为5min~30min。The volume ratio of the first solution to the second solution is from 1 to 2:1. The rate of centrifugation is preferably from 3000 rpm to 4000 rpm, and the centrifugation time is from 5 min to 30 min.
可以理解，在其他实施方式中，具有六方晶体结构的氧化锌可以为市售的具有六方晶体结构的氧化锌。It will be appreciated that in other embodiments, the zinc oxide having a hexagonal crystal structure may be a commercially available zinc oxide having a hexagonal crystal structure.
步骤120：将单层氧化石墨烯加入溶剂中，配制氧化石墨烯的分散液，向氧化石墨烯的分散液中加入具有六方晶体结构的氧化锌，然后加入稳定剂，分散均匀得到胶体溶液。Step 120: adding a single layer of graphene oxide to a solvent to prepare a dispersion of graphene oxide, adding zinc oxide having a hexagonal crystal structure to the dispersion of graphene oxide, adding a stabilizer, and uniformly dispersing to obtain a colloidal solution.
溶剂选自选自水、二甲氧基乙烷、质量百分比浓度为10%的聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。上述溶剂的沸点较高，有助于低压下形成石墨烯量子点，且能防止溶剂自身热解形成的碳点作为杂质进入体系。优选地，溶剂选自丙三醇、N-甲基吡咯烷酮及质量百分比浓度为10%的聚乙烯醇的水溶液中的至少一种。The solvent is selected from at least one selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol having a 10% by mass concentration, glycerin, triethylene glycol, and N-methylpyrrolidone. The above solvent has a high boiling point, contributes to the formation of graphene quantum dots at a low pressure, and prevents carbon dots formed by pyrolysis of the solvent itself from entering the system as impurities. Preferably, the solvent is at least one selected from the group consisting of glycerol, N-methylpyrrolidone, and an aqueous solution of polyvinyl alcohol having a 10% by mass concentration.
优选地，单层氧化石墨烯与具有六方晶体结构的氧化锌的质量比为1~10:1。Preferably, the mass ratio of the single-layer graphene oxide to the zinc oxide having the hexagonal crystal structure is from 1 to 10:1.
优选地，氧化石墨烯的分散液中，单层氧化石墨烯的浓度为2mg/mL~10mg/mL。Preferably, in the dispersion of graphene oxide, the concentration of the single-layer graphene oxide is 2 mg/mL to 10 mg/mL.
稳定剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。优选地，稳定剂选自聚甲基吡咯烷酮及四丁基溴化铵中的至少一种。The stabilizer is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, tetrabutylammonium bromide and octadecyltrimethylammonium bromide. At least one of them. Preferably, the stabilizer is selected from at least one of polymethylpyrrolidone and tetrabutylammonium bromide.
稳定剂用于促进具有六方晶体结构的氧化锌在体系中的分散。优选地，稳定剂在胶体溶液中的质量百分比浓度为0.1%~3%。Stabilizers are used to promote the dispersion of zinc oxide having a hexagonal crystal structure in the system. Preferably, the mass percent concentration of the stabilizer in the colloidal solution is from 0.1% to 3%.
优选地，为了使单层氧化石墨烯和具有六方晶体结构的氧化锌充分分散均匀，分散是于超声波下进行搅拌分散。超声波的功率为120w~300w，搅拌分散的时间为1h~2h。Preferably, in order to sufficiently disperse the single-layer graphene oxide and the zinc oxide having a hexagonal crystal structure, the dispersion is stirred and dispersed under ultrasonic waves. The ultrasonic power is 120w~300w, and the stirring and dispersing time is 1h~2h.
步骤130：将胶体溶液于160℃~300℃下进行水热反应0.5h~2h，得到含有石墨烯量子点的悬浊液。Step 130: hydrothermal reaction of the colloidal solution at 160 ° C to 300 ° C for 0.5 h to 2 h to obtain a suspension containing graphene quantum dots.
将胶体溶液放入聚四氟乙烯为内衬的水热反应釜中，在160℃~300℃进行水热反应0.5h~2h，单层氧化石墨烯裂解生成石墨烯量子点，反应完成后得到含有石墨烯量子点的悬浊液。The colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 160 ° C ~ 300 ° C for 0.5 h ~ 2 h. The single layer of graphene oxide was cracked to form graphene quantum dots. A suspension containing graphene quantum dots.
步骤140：向含有石墨烯量子点的悬浊液中加入酸使含有石墨烯量子点的悬浊液变澄清，将变澄清的含有石墨烯量子点的悬浊液进行过滤，取滤液，将滤液的pH值调节为7~8并搅拌，然后过滤，弃沉淀，得到含有石墨烯量子点的溶液。Step 140: adding an acid to a suspension containing graphene quantum dots to clarify a suspension containing graphene quantum dots, filtering a clear suspension containing graphene quantum dots, taking a filtrate, and separating the filtrate. The pH was adjusted to 7-8 and stirred, then filtered, and the precipitate was discarded to obtain a solution containing graphene quantum dots.
向含有石墨烯量子点的悬浊液加入酸以调节含有石墨烯量子点的悬浊液的pH值为2~3。当pH值为2~3时，含有石墨烯量子点的悬浊液变澄清。An acid is added to the suspension containing graphene quantum dots to adjust the pH of the suspension containing graphene quantum dots to 2 to 3. When the pH is 2 to 3, the suspension containing graphene quantum dots becomes clear.
优选地，上述用于调节pH值的酸为pH值为1的盐酸。Preferably, the above acid for adjusting the pH is hydrochloric acid having a pH of 1.
将变澄清的含有石墨烯量子点的悬浊液进行过滤，以除去水热反应后未被裂解而是被高温还原的石墨烯片。The clarified suspension containing graphene quantum dots was filtered to remove graphene sheets which were not cracked after the hydrothermal reaction but were reduced at a high temperature.
使用质量百分比浓度为10%~25%的氨水将滤液的pH值调节为7~8。将滤液的pH值调节为7~8并搅拌使氢氧化锌沉降，过滤除去氢氧化锌，得到含有石墨烯量子点的溶液。The pH of the filtrate was adjusted to 7-8 using ammonia water having a mass percentage concentration of 10% to 25%. The pH of the filtrate was adjusted to 7 to 8 and stirred to precipitate zinc hydroxide, and zinc hydroxide was removed by filtration to obtain a solution containing graphene quantum dots.
上述两个过滤操作均使用0.22μm~0.8μm的微孔滤膜或0.22μm~0.8μm的快速滤纸进行过滤。Both of the above filtration operations were carried out using a 0.22 μm to 0.8 μm microporous membrane or a 0.22 μm to 0.8 μm flash filter.
步骤150：将含有石墨烯量子点的溶液进行萃取，然后蒸发除去萃取剂，得到石墨烯量子点。Step 150: extracting a solution containing graphene quantum dots, and then removing the extractant by evaporation to obtain graphene quantum dots.
萃取剂选自甲醇、乙醇、异丙醇、乙腈、乙酸乙酯、氯仿、二氯甲烷、四氯化碳、***、甲苯、苯、环己烷、石油醚、己烷及戊烷中的至少一种。优选地，萃取剂选自甲醇、乙酸乙酯、乙醇、乙腈、氯仿、二氯甲烷及石油醚中的至少一种。The extracting agent is selected from at least methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, chloroform, dichloromethane, carbon tetrachloride, diethyl ether, toluene, benzene, cyclohexane, petroleum ether, hexane and pentane. One. Preferably, the extractant is selected from at least one of methanol, ethyl acetate, ethanol, acetonitrile, chloroform, dichloromethane, and petroleum ether.
优选地，含有石墨烯量子点的溶液与萃取剂的体积比为1:1~5。萃取完成后，将含有石墨烯量子点的萃取剂进行旋转蒸发，以除去萃取剂，得到石墨烯量子点。石墨烯量子点的尺寸为3nm~50nm，且尺寸分布较窄，荧光颜色可调。Preferably, the volume ratio of the solution containing the graphene quantum dots to the extractant is 1:1 to 5. After the extraction is completed, the extractant containing graphene quantum dots is subjected to rotary evaporation to remove the extractant to obtain graphene quantum dots. The size of the graphene quantum dots is 3 nm to 50 nm, and the size distribution is narrow, and the fluorescent color is adjustable.
通过简单的萃取就能够从含有石墨烯量子点的溶液中获得石墨烯量子点，而无需像传统的石墨烯量子点的制备方法那样采用层析的方法进行提纯，工艺较为简单。Graphene quantum dots can be obtained from a solution containing graphene quantum dots by simple extraction without using a chromatographic method for purification as in the conventional method for preparing graphene quantum dots, and the process is relatively simple.
上述石墨烯量子点的制备方法使用具有六方晶体结构的氧化锌作为诱导石墨烯量子点生长的种子晶核，具有六方晶体结构的氧化锌与氧化石墨烯属于同种格子的晶体，且作为氧化物，氧化锌的暴露晶面上的氧原子能与氧化石墨烯上的羟基形成氢键而使氧化石墨烯被吸附在氧化锌的暴露晶面上，从而可以通过氧化锌作为种子晶核来诱导石墨烯量子点的生长并通过控制氧化锌的尺寸来间接控制吸附在氧化锌表面的氧化石墨烯的量和尺寸；并且，在随后的水热反应中，使氧化锌表面的氧化石墨烯保持吸附的同时被裂解，形成石墨烯量子点，也就间接地控制了石墨烯量子点的尺寸大小与分布情况，从而获得尺寸分布较窄的石墨烯量子点。The above method for preparing graphene quantum dots uses zinc oxide having a hexagonal crystal structure as a seed crystal nucleus for inducing growth of graphene quantum dots, and zinc oxide having a hexagonal crystal structure and graphene oxide belong to the same kind of lattice crystal, and as an oxide The oxygen atom on the exposed crystal face of the zinc oxide can form a hydrogen bond with the hydroxyl group on the graphene oxide to cause the graphene oxide to be adsorbed on the exposed crystal face of the zinc oxide, thereby inducing the graphene through the zinc oxide as the seed crystal nucleus. Growth of quantum dots and indirectly controlling the amount and size of graphene oxide adsorbed on the surface of zinc oxide by controlling the size of zinc oxide; and, in the subsequent hydrothermal reaction, while maintaining the adsorption of graphene oxide on the surface of zinc oxide It is cleaved to form graphene quantum dots, which indirectly controls the size and distribution of graphene quantum dots, thereby obtaining graphene quantum dots with narrow size distribution.
经实验表明，上述石墨烯量子点的制备方法所制备得到的石墨烯量子点的尺寸与所用的具有六方晶体结构的氧化锌的粒径相当，通过控制具有六方晶体结构的氧化锌的粒径能够间接控制石墨烯量子点的尺寸大小，获得尺寸分布较窄的石墨烯量子点，而无需像传统的石墨烯量子点的制备方法那样，制备得到尺寸分布较广的石墨烯量子点后还需要繁琐的分离技术将不同尺寸的石墨烯量子点一一分离出来。Experiments have shown that the size of the graphene quantum dots prepared by the above method for preparing graphene quantum dots is equivalent to the particle size of zinc oxide having a hexagonal crystal structure, and the particle size of zinc oxide having a hexagonal crystal structure can be controlled. Indirectly controlling the size of graphene quantum dots and obtaining graphene quantum dots with narrow size distribution, without the need to prepare a graphene quantum dot with a large size distribution after the preparation of a conventional graphene quantum dot The separation technique separates graphene quantum dots of different sizes one by one.
使用上述石墨烯量子点的制备方法制备石墨烯量子点，石墨烯量子点的尺寸和荧光颜色可调、且尺寸分布窄、量子产率高，从而能够有效地在LED、生物成像等领域得到较好的应用。The graphene quantum dots are prepared by using the above-mentioned method for preparing graphene quantum dots. The size and fluorescent color of the graphene quantum dots are adjustable, the size distribution is narrow, and the quantum yield is high, so that it can be effectively obtained in the fields of LED and biological imaging. Good application.
并且，上述石墨烯量子点的制备方法相对于传统的自下而上的方法，工艺较为简单，无需像传统的自下而上的方法那样，所有的中间体都需要用硅凝胶色谱法纯化并用标准表征法确认，避免了过于繁琐的操作，有利于工业生产与扩大应用。Moreover, the above-described method for preparing graphene quantum dots is simpler than the conventional bottom-up method, and it is not necessary to use a silica gel chromatography method as in the conventional bottom-up method. It is confirmed by standard characterization method, avoiding too cumbersome operations, and is conducive to industrial production and expansion of applications.
以下通过具体实施例对上述石墨烯量子点的制备方法进一步阐述。The preparation method of the above graphene quantum dots is further illustrated by the following specific examples.
实施例1Example 1
1、将醋酸锌溶于乙醇中，于50℃水浴下加热1 h，然后加入聚甲基吡咯烷酮，得到第一溶液。其中，醋酸锌的质量百分比浓度为5%，聚甲基吡咯烷酮的质量百分比浓度为0.2%。按体积比1:5将质量百分比浓度为25%的氨水和无水乙醇混合，配制氨水和乙醇的混合溶液，并加入氢氧化钠得到第二溶液。其中，氢氧化钠在第二溶液中的浓度为0.1mg/L。将第一溶液和第二溶液按体积比1:1混合，以60rpm的速率搅拌2h，然后以3000rpm的速率离心5 min，取沉淀，洗涤沉淀得到具有六方晶体结构的氧化锌，该具有六方晶体结构的氧化锌为球形，粒径为7.5nm。1. Dissolve zinc acetate in ethanol and heat it in a water bath at 50 °C. h, then polymethylpyrrolidone is added to give a first solution. Among them, the mass percentage concentration of zinc acetate is 5%, and the mass percentage concentration of polymethylpyrrolidone is 0.2%. A mixture of ammonia water and ethanol was prepared by mixing 25% by mass of ammonia water and absolute ethanol at a volume ratio of 1:5, and sodium hydroxide was added to obtain a second solution. Among them, the concentration of sodium hydroxide in the second solution was 0.1 mg/L. The first solution and the second solution were mixed at a volume ratio of 1:1, stirred at a rate of 60 rpm for 2 hours, and then centrifuged at a rate of 3000 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure, and the zinc oxide having a hexagonal crystal structure was spherical and had a particle diameter of 7.5 nm.
2、将单层氧化石墨烯加入去离子水中，配制单层氧化石墨烯的浓度为2mg/mL的氧化石墨烯的分散液，向氧化石墨烯的分散液中加入上述具有六方晶体结构的氧化锌，然后加入聚甲基吡咯烷酮，于120w的超声波功率下搅拌分散2h，分散均匀得到胶体溶液。其中，单层氧化石墨烯与具有六方晶相结构的氧化锌的质量比为1:1，聚甲基吡咯烷酮在胶体溶液中的质量百分比浓度为0.1%。2. Adding a single layer of graphene oxide to deionized water to prepare a dispersion of graphene oxide having a concentration of 2 mg/mL of a single layer of graphene oxide, and adding the above-mentioned zinc oxide having a hexagonal crystal structure to the dispersion of graphene oxide. Then, polymethylpyrrolidone was added, and the mixture was stirred and dispersed for 2 hours under ultrasonic power of 120 W, and uniformly dispersed to obtain a colloidal solution. Among them, the mass ratio of the single-layer graphene oxide to the zinc oxide having a hexagonal crystal structure is 1:1, and the mass percentage concentration of the polymethylpyrrolidone in the colloidal solution is 0.1%.
3、将胶体溶液放入聚四氟乙烯为内衬的水热反应釜中，在160℃进行水热反应2h，反应完成后得到含有石墨烯量子点的悬浊液。3. The colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermally reacted at 160 ° C for 2 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
4、向含有石墨烯量子点的悬浊液中加入pH值为1的盐酸调节含有石墨烯量子点的悬浊液的pH值为2，使含有石墨烯量子的悬浊液变为澄清，用0.22μm的微孔滤膜将变澄清的含有石墨烯量子点的悬浊液进行过滤，取滤液，向该滤液中加入质量百分比浓度为10%的氨水调整滤液的pH值为7并搅拌，然后用0.22μm的微孔滤膜过滤，弃去沉淀，取滤液，得到含有石墨烯量子点的溶液。4. Adding hydrochloric acid with pH 1 to the suspension containing graphene quantum dots, adjusting the pH of the suspension containing graphene quantum dots to 2, and making the suspension containing graphene quantum clear. A 0.22 μm microporous membrane was used to filter the clarified suspension containing graphene quantum dots, and the filtrate was taken. To the filtrate, 10% by mass of ammonia water was added to adjust the pH of the filtrate to 7 and stirred, and then stirred. The mixture was filtered through a 0.22 μm microporous membrane, the precipitate was discarded, and the filtrate was taken to obtain a solution containing graphene quantum dots.
5、使用乙醇作为萃取剂将含有石墨烯量子点溶液进行萃取。其中，含有石墨烯量子点的溶液与萃取剂的体积比为1:1。萃取完成后，采用旋转蒸发除去萃取剂，得到石墨烯量子点。5. Extracting the graphene-containing quantum dot solution using ethanol as an extractant. Wherein, the volume ratio of the solution containing the graphene quantum dots to the extracting agent is 1:1. After the extraction is completed, the extractant is removed by rotary evaporation to obtain graphene quantum dots.
在制备的石墨烯量子点中随机取两份样品进行AFM表征，结果分别如图2和图3所示。由图2看出，石墨烯量子点的尺寸为8.3nm。由图3可看出，石墨烯量子点的尺寸为7.9nm。可见，采用上述石墨烯量子的点的制备方法制备得到石墨烯量子点的尺寸较小，与所使用的具有六方晶体结构的氧化锌种子晶核的尺寸接近，且尺寸分布较窄。Two samples were randomly taken from the prepared graphene quantum dots for AFM characterization, and the results are shown in Fig. 2 and Fig. 3, respectively. As seen from Figure 2, the size of the graphene quantum dots is 8.3 nm. As can be seen from Figure 3, the size of the graphene quantum dots is 7.9 nm. It can be seen that the size of the graphene quantum dots prepared by the method for preparing the above-mentioned graphene quantum dots is small, and is close to the size of the zinc oxide seed crystal nucleus having a hexagonal crystal structure, and the size distribution is narrow.
实施例2Example 2
1、将氯化锌溶于异丙醇中，于60℃水浴下加热2 h，然后加入羟丙基纤维素，得到第一溶液。其中，氯化锌的质量百分比浓度为25%，羟丙基纤维素的质量百分比浓度为1%。按体积比1:8将质量百分比浓度为25%的氨水和无水乙醇混合，配制氨水和乙醇的混合溶液，并加入氢氧化钾得到第二溶液。其中，氢氧化钾在第二溶液中的浓度为0.5mg/L。将第一溶液和第二溶液按体积比2:1混合，以30rpm的速率搅拌3h，然后以4000rpm的速率离心15 min，取沉淀，洗涤沉淀得到具有六方晶体结构的氧化锌，该具有六方晶体结构的氧化锌为六角形，粒径为15 nm。1. Dissolve zinc chloride in isopropyl alcohol and heat in a water bath at 60 ° C. 2 h, then hydroxypropylcellulose was added to give a first solution. Among them, the mass percentage concentration of zinc chloride is 25%, and the mass percentage concentration of hydroxypropyl cellulose is 1%. A mixture of ammonia water and ethanol was prepared by mixing 25% by mass of ammonia water and absolute ethanol at a volume ratio of 1:8, and potassium hydroxide was added to obtain a second solution. Among them, the concentration of potassium hydroxide in the second solution was 0.5 mg/L. The first solution and the second solution were mixed at a volume ratio of 2:1, stirred at a rate of 30 rpm for 3 hours, and then centrifuged at a rate of 4000 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure. The zinc oxide having a hexagonal crystal structure was hexagonal and had a particle diameter of 15 nm.
2、将单层氧化石墨烯加入丙三醇中，配制单层氧化石墨烯的浓度为10mg/mL的氧化石墨烯的分散液，向氧化石墨烯的分散液中加入上述具有六方晶体结构的氧化锌，然后加入羟丙基纤维素，于300w的超声波功率下搅拌分散1h，分散均匀得到胶体溶液。其中，单层氧化石墨烯与具有六方晶相结构的氧化锌的质量比为10:1，羟丙基纤维素在胶体溶液中的质量百分比浓度为3%。2. Adding a single layer of graphene oxide to glycerol to prepare a dispersion of graphene oxide having a monolayer of graphene oxide at a concentration of 10 mg/mL, and adding the above-mentioned oxidation having a hexagonal crystal structure to the dispersion of graphene oxide. Zinc, then hydroxypropylcellulose was added, and the mixture was stirred and dispersed for 1 hour under an ultrasonic power of 300 W, and uniformly dispersed to obtain a colloidal solution. Among them, the mass ratio of the single-layer graphene oxide to the zinc oxide having a hexagonal crystal structure is 10:1, and the mass percentage concentration of the hydroxypropyl cellulose in the colloidal solution is 3%.
3、将胶体溶液放入聚四氟乙烯为内衬的水热反应釜中，在300℃进行水热反应0.5h，反应完成后得到含有石墨烯量子点的悬浊液。3. The colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 300 ° C for 0.5 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
4、向含有石墨烯量子点的悬浊液中加入pH值为1的盐酸调节含有石墨烯量子点的悬浊液的pH值为3，使含有石墨烯量子的悬浊液变为澄清，用0.5μm的微孔滤膜将变澄清的含有石墨烯量子点的悬浊液进行过滤，取滤液，向该滤液中加入质量百分比浓度为10%的氨水调整滤液的pH值为8并搅拌，然后用0.5μm的微孔滤膜过滤，弃去沉淀，取滤液，得到含有石墨烯量子点的溶液。4. Adding hydrochloric acid having a pH of 1 to a suspension containing graphene quantum dots, adjusting the pH of the suspension containing graphene quantum dots to 3, and making the suspension containing graphene quantum clarified. A 0.5 μm microporous membrane was used to filter the clarified suspension containing graphene quantum dots, and the filtrate was taken. To the filtrate, 10% by mass aqueous ammonia was added to adjust the pH of the filtrate to 8 and stirred. The mixture was filtered through a 0.5 μm microporous membrane, the precipitate was discarded, and the filtrate was taken to obtain a solution containing graphene quantum dots.
5、使用乙腈作为萃取剂将含有石墨烯量子点溶液进行萃取。其中，含有石墨烯量子点的溶液与萃取剂的体积比为1:5。萃取完成后，采用旋转蒸发除去萃取剂，得到石墨烯量子点。5. Extracting the graphene-containing quantum dot solution using acetonitrile as an extractant. Wherein, the volume ratio of the solution containing the graphene quantum dots to the extracting agent is 1:5. After the extraction is completed, the extractant is removed by rotary evaporation to obtain graphene quantum dots.
实施例3Example 3
1、将氯化锌溶于乙二醇和异丙醇按体积比1:1混合的混合溶剂中，于55℃水浴下加热3 h，然后加入质量比为2:1的羟甲基纤维素和羟乙基纤维素，得到第一溶液。其中，氯化锌的质量百分比浓度为20%，羟甲基纤维素的质量百分比浓度为0.4%，羟乙基纤维素的质量百分比浓度为0.4%。按体积比1:6将质量百分比浓度为28%的氨水和无水乙醇混合，配制氨水和乙醇的混合溶液，并加入氢氧化钾得到第二溶液。其中，氢氧化钾在第二溶液中的浓度为0.3mg/L。将第一溶液和第二溶液按体积比1.5:1混合，以50rpm的速率搅拌2.5h，然后以3500rpm的速率离心10 min，取沉淀，洗涤沉淀得到具有六方晶体结构的氧化锌，该具有六方晶体结构的氧化锌为棒状，粒径为23 nm。1. Dissolve zinc chloride in a mixed solvent of ethylene glycol and isopropyl alcohol in a volume ratio of 1:1, and heat it in a water bath at 55 ° C. h, then hydroxymethylcellulose and hydroxyethylcellulose in a mass ratio of 2:1 were added to obtain a first solution. Among them, the mass percentage concentration of zinc chloride is 20%, the mass percentage concentration of hydroxymethyl cellulose is 0.4%, and the mass percentage concentration of hydroxyethyl cellulose is 0.4%. A mixture of ammonia water and ethanol was prepared by mixing a mass percentage of 28% ammonia water with absolute ethanol at a volume ratio of 1:6, and potassium hydroxide was added to obtain a second solution. Among them, the concentration of potassium hydroxide in the second solution was 0.3 mg/L. The first solution and the second solution were mixed at a volume ratio of 1.5:1, stirred at a rate of 50 rpm for 2.5 h, and then centrifuged at a rate of 3500 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure. The zinc oxide having a hexagonal crystal structure was rod-shaped and had a particle diameter of 23 nm.
2、将单层氧化石墨烯加入质量百分比浓度为10%的聚乙烯醇的水溶液中，配制单层氧化石墨烯的浓度为8mg/mL的氧化石墨烯的分散液，向氧化石墨烯的分散液中加入上述具有六方晶体结构的氧化锌，然后加入质量比为1:1的聚甲基吡咯烷酮和四丁基溴化铵，于180w的超声波功率下搅拌分散1.8h，分散均匀得到胶体溶液。其中，单层氧化石墨烯与具有六方晶相结构的氧化锌的质量比为8:1，聚甲基吡咯烷酮在胶体溶液中的质量百分比浓度为0.4%，四丁基溴化铵在胶体溶液中的质量百分比浓度为0.4%。2. Adding a single layer of graphene oxide to an aqueous solution of polyvinyl alcohol having a mass percentage of 10% to prepare a dispersion of graphene oxide having a monolayer graphene oxide concentration of 8 mg/mL, and a dispersion of graphene oxide. The above zinc oxide having a hexagonal crystal structure was added thereto, and then polymethylpyrrolidone and tetrabutylammonium bromide in a mass ratio of 1:1 were added, and the mixture was stirred and dispersed for 1.8 hours under an ultrasonic power of 180 W, and uniformly dispersed to obtain a colloidal solution. Wherein, the mass ratio of the single-layer graphene oxide to the zinc oxide having the hexagonal phase structure is 8:1, the mass concentration of the polymethylpyrrolidone in the colloidal solution is 0.4%, and the tetrabutylammonium bromide is in the colloidal solution. The mass percentage concentration is 0.4%.
3、将胶体溶液放入聚四氟乙烯为内衬的水热反应釜中，在250℃进行水热反应1h，反应完成后得到含有石墨烯量子点的悬浊液。3. The colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermal reaction was carried out at 250 ° C for 1 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
4、向含有石墨烯量子点的悬浊液中加入pH值为1的盐酸调节含有石墨烯量子点的悬浊液的pH值为2.5，使含有石墨烯量子的悬浊液变为澄清，用0.8μm的微孔滤膜将变澄清的含有石墨烯量子点的悬浊液进行过滤，取滤液，向该滤液中加入质量百分比浓度为10%的氨水调整滤液的pH值为7.5并搅拌，然后用0.8μm的微孔滤膜过滤，弃去沉淀，取滤液，得到含有石墨烯量子点的溶液。4. Adding hydrochloric acid with pH 1 to the suspension containing graphene quantum dots, adjusting the pH of the suspension containing graphene quantum dots to 2.5, and making the suspension containing graphene quantum clear. A 0.8 μm microporous membrane was used to filter the clarified suspension containing graphene quantum dots, and the filtrate was taken. To the filtrate, 10% by mass of ammonia water was added to adjust the pH of the filtrate to 7.5 and stirred. The mixture was filtered through a 0.8 μm microporous membrane, the precipitate was discarded, and the filtrate was taken to obtain a solution containing graphene quantum dots.
5、使用氯仿作为萃取剂将含有石墨烯量子点溶液进行萃取。其中，含有石墨烯量子点的溶液与萃取剂的体积比为1:3。萃取完成后，采用旋转蒸发除去萃取剂，得到石墨烯量子点。5. Extracting the graphene-containing quantum dot solution using chloroform as an extractant. Wherein, the volume ratio of the solution containing the graphene quantum dots to the extracting agent is 1:3. After the extraction is completed, the extractant is removed by rotary evaporation to obtain graphene quantum dots.
实施例4Example 4
1、将醋酸锌溶于乙二醇中，于56℃水浴下加热0.5 h，然后加入四丁基溴化铵，得到第一溶液。其中，醋酸锌的质量百分比浓度为15%，四丁基溴化铵的质量百分比浓度为0.4%。按体积比1:7将质量百分比浓度为28%的氨水和无水乙醇混合，配制氨水和乙醇的混合溶液，并加入氢氧化钠得到第二溶液。其中，氢氧化钠在第二溶液中的浓度为0.4mg/L。将第一溶液和第二溶液按体积比2:1混合，以55rpm的速率搅拌3h，然后以3800rpm的速率离心30 min，取沉淀，洗涤沉淀得到具有六方晶体结构的氧化锌，该具有六方晶体结构的氧化锌为球形，粒径为28 nm。1. Dissolve zinc acetate in ethylene glycol and heat it in a water bath at 56 °C. h, then tetrabutylammonium bromide was added to give a first solution. Among them, the mass percentage concentration of zinc acetate is 15%, and the mass percentage concentration of tetrabutylammonium bromide is 0.4%. A mixture of ammonia water and ethanol was prepared by mixing a mass percentage of 28% ammonia water with absolute ethanol at a volume ratio of 1:7, and adding a sodium hydroxide to obtain a second solution. Among them, the concentration of sodium hydroxide in the second solution was 0.4 mg/L. The first solution and the second solution were mixed at a volume ratio of 2:1, stirred at a rate of 55 rpm for 3 hours, and then centrifuged at a rate of 3800 rpm. Min, the precipitate was taken, and the precipitate was washed to obtain zinc oxide having a hexagonal crystal structure. The zinc oxide having a hexagonal crystal structure was spherical and had a particle diameter of 28 nm.
2、将单层氧化石墨烯加入体积比为1:1的丙三醇和N-甲基吡咯烷酮的混合溶剂中，配制单层氧化石墨烯的浓度为5mg/mL的氧化石墨烯的分散液，向氧化石墨烯的分散液中加入上述具有六方晶体结构的氧化锌，然后加入羧甲基纤维素，于250w的超声波功率下搅拌分散1h，分散均匀得到胶体溶液。其中，单层氧化石墨烯与具有六方晶相结构的氧化锌的质量比为5:1，羧甲基纤维素在胶体溶液中的质量百分比浓度为2%。2. Adding a single layer of graphene oxide to a mixed solvent of glycerol and N-methylpyrrolidone in a volume ratio of 1:1 to prepare a dispersion of graphene oxide having a monolayer graphene oxide concentration of 5 mg/mL, The above-mentioned zinc oxide oxide dispersion was added to the above-mentioned zinc oxide having a hexagonal crystal structure, and then carboxymethylcellulose was added thereto, and the mixture was stirred and dispersed for 1 hour under an ultrasonic power of 250 W, and uniformly dispersed to obtain a colloidal solution. Among them, the mass ratio of the single-layer graphene oxide to the zinc oxide having a hexagonal crystal structure is 5:1, and the mass percentage concentration of the carboxymethyl cellulose in the colloidal solution is 2%.
3、将胶体溶液放入聚四氟乙烯为内衬的水热反应釜中，在200℃进行水热反应1.5h，反应完成后得到含有石墨烯量子点的悬浊液。3. The colloidal solution was placed in a hydrothermal reaction vessel lined with polytetrafluoroethylene, and hydrothermally reacted at 200 ° C for 1.5 h. After completion of the reaction, a suspension containing graphene quantum dots was obtained.
4、向含有石墨烯量子点的悬浊液中加入pH值为1的盐酸调节含有石墨烯量子点的悬浊液的pH值为3，使含有石墨烯量子的悬浊液变为澄清，用0.22μm的快速滤纸将变澄清的含有石墨烯量子点的悬浊液进行过滤，取滤液，向该滤液中加入质量百分比浓度为25%的氨水调整滤液的pH值为7.5并搅拌，然后用0.22μm的快速滤纸过滤，弃去沉淀，取滤液，得到含有石墨烯量子点的溶液。4. Adding hydrochloric acid having a pH of 1 to a suspension containing graphene quantum dots, adjusting the pH of the suspension containing graphene quantum dots to 3, and making the suspension containing graphene quantum clarified. A 0.22 μm fast filter paper was used to filter the clarified suspension containing graphene quantum dots, and the filtrate was taken. To the filtrate was added a 25% by mass aqueous ammonia solution to adjust the pH of the filtrate to 7.5 and stir, and then 0.22. The filter paper of μm was filtered, the precipitate was discarded, and the filtrate was taken to obtain a solution containing graphene quantum dots.
5、使用二氯甲烷和石油醚按体积比1:1混合的混合溶剂作为萃取剂将含有石墨烯量子点溶液进行萃取。其中，含有石墨烯量子点的溶液与萃取剂的体积比为1:4。萃取完成后，采用旋转蒸发除去萃取剂，得到石墨烯量子点。5. The graphene quantum dot solution is extracted by using a mixed solvent of dichloromethane and petroleum ether in a volume ratio of 1:1 as an extractant. Wherein, the volume ratio of the solution containing the graphene quantum dots to the extracting agent is 1:4. After the extraction is completed, the extractant is removed by rotary evaporation to obtain graphene quantum dots.
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。The above-mentioned embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims (11)

  1. 一种石墨烯量子点的制备方法，其特征在于，包括如下步骤：A method for preparing graphene quantum dots, comprising the steps of:
    提供具有六方晶体结构的氧化锌作为种子晶核，所述具有六方晶体结构的氧化锌的粒径为5nm~30nm；Providing zinc oxide having a hexagonal crystal structure as a seed crystal nucleus, wherein the zinc oxide having a hexagonal crystal structure has a particle diameter of 5 nm to 30 nm;
    将单层氧化石墨烯加入溶剂中，配制氧化石墨烯的分散液，向所述氧化石墨烯的分散液中加入所述具有六方晶体结构的氧化锌，然后加入稳定剂，分散均匀得到胶体溶液；Adding a single layer of graphene oxide to a solvent to prepare a dispersion of graphene oxide, adding the zinc oxide having a hexagonal crystal structure to the dispersion of graphene oxide, adding a stabilizer, and uniformly dispersing to obtain a colloidal solution;
    将所述胶体溶液于160℃~300℃下进行水热反应0.5h~2h，得到含有石墨烯量子点的悬浊液；The colloidal solution is hydrothermally reacted at 160 ° C to 300 ° C for 0.5 h to 2 h to obtain a suspension containing graphene quantum dots;
    向所述含有石墨烯量子点的悬浊液中加入酸使所述含有石墨烯量子点的悬浊液变澄清，将变澄清的所述含有石墨烯量子点的悬浊液进行过滤，取滤液，将所述滤液的pH值调节为7~8并搅拌，然后过滤，弃沉淀，得到含有石墨烯量子点的溶液；及Adding an acid to the suspension containing the graphene quantum dots causes the suspension containing the graphene quantum dots to be clarified, and filtering the clarified suspension containing the graphene quantum dots to obtain a filtrate Adjusting the pH of the filtrate to 7-8 and stirring, then filtering, and discarding the precipitate to obtain a solution containing graphene quantum dots;
    将所述含有石墨烯量子点的溶液进行萃取，然后蒸发除去萃取剂，得到石墨烯量子点。The solution containing the graphene quantum dots is extracted, and then the extractant is removed by evaporation to obtain graphene quantum dots.
  2. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述具有六方晶体结构的氧化锌按如下方法制备：The method for preparing a graphene quantum dot according to claim 1, wherein the zinc oxide having a hexagonal crystal structure is prepared as follows:
    将锌盐溶于醇类溶剂中，于50℃~60℃水浴下加热0.5h~4h，然后加入保护剂，得到第一溶液；Dissolving the zinc salt in an alcohol solvent, heating in a water bath at 50 ° C ~ 60 ° C for 0.5 h ~ 4 h, and then adding a protective agent to obtain a first solution;
    配制氨水和乙醇的混合溶液，并加入氢氧化钠或氢氧化钾，得到第二溶液，其中，所述氢氧化钠或氢氧化钾在所述第二溶液中的浓度为0.1mg/L~0.5mg/L；Preparing a mixed solution of ammonia water and ethanol, and adding sodium hydroxide or potassium hydroxide to obtain a second solution, wherein the concentration of the sodium hydroxide or potassium hydroxide in the second solution is 0.1 mg/L to 0.5 Mg/L;
    将所述第一溶液和第二溶液混合，搅拌2h~3h，离心取沉淀，洗涤所述沉淀得到所述具有六方晶体结构的氧化锌。The first solution and the second solution are mixed, stirred for 2 h to 3 h, and the precipitate is taken by centrifugation, and the precipitate is washed to obtain the zinc oxide having a hexagonal crystal structure.
  3. 根据权利要求2所述的石墨烯量子点的制备方法，其特征在于，所述第一溶液中，所述锌盐的质量百分比浓度为5%~25%，所述保护剂的质量百分比浓度为0.2%~1%。The method for preparing a graphene quantum dot according to claim 2, wherein a concentration percentage of the zinc salt in the first solution is 5% to 25%, and a mass percentage concentration of the protective agent is 0.2%~1%.
  4. 根据权利要求2所述的石墨烯量子点的制备方法，其特征在于，所述保护剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。The method for preparing a graphene quantum dot according to claim 2, wherein the protective agent is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and carboxymethyl At least one of a cellulose, tetrabutylammonium bromide, and octadecyltrimethylammonium bromide.
  5. 根据权利要求2所述的石墨烯量子点的制备方法，其特征在于，所述氨水和乙醇的体积比为1:5~8。The method for preparing a graphene quantum dot according to claim 2, wherein the volume ratio of the ammonia water to the ethanol is 1:5-8.
  6. 根据权利要求2所述的石墨烯量子点的制备方法，其特征在于，所述第一溶液和第二溶液的体积比为1~2:1。The method for preparing a graphene quantum dot according to claim 2, wherein a volume ratio of the first solution to the second solution is 1 to 2:1.
  7. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述氧化石墨烯的分散液中，所述单层氧化石墨烯的浓度为2mg/mL~10mg/mL。The method for producing a graphene quantum dot according to claim 1, wherein in the dispersion of graphene oxide, the concentration of the single-layer graphene oxide is 2 mg/mL to 10 mg/mL.
  8. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述稳定剂选自聚甲基吡咯烷酮、羟丙基纤维素、羟甲基纤维素、羟乙基纤维素、羧甲基纤维素、四丁基溴化铵及十八烷基三甲基溴化铵中的至少一种。The method for preparing a graphene quantum dot according to claim 1, wherein the stabilizer is selected from the group consisting of polymethylpyrrolidone, hydroxypropylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and carboxymethyl At least one of a cellulose, tetrabutylammonium bromide, and octadecyltrimethylammonium bromide.
  9. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述稳定剂在所述胶体溶液中的中的质量百分比浓度为0.1%~3%。The method for preparing a graphene quantum dot according to claim 1, wherein a concentration percentage of the stabilizer in the colloidal solution is 0.1% to 3%.
  10. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述溶剂选自水、二甲氧基乙烷、质量百分比浓度为10%的聚乙烯醇的水溶液、丙三醇、三缩二乙二醇及N-甲基吡咯烷酮中的至少一种。The method for preparing a graphene quantum dot according to claim 1, wherein the solvent is selected from the group consisting of water, dimethoxyethane, an aqueous solution of polyvinyl alcohol having a mass percentage of 10%, glycerol, At least one of triethylene glycol and N-methylpyrrolidone.
  11. 根据权利要求1所述的石墨烯量子点的制备方法，其特征在于，所述单层氧化石墨烯与具有六方晶体结构的氧化锌的质量比为1~10:1。The method for preparing a graphene quantum dot according to claim 1, wherein a mass ratio of the single-layer graphene oxide to zinc oxide having a hexagonal crystal structure is 1 to 10:1.
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