KR20170018129A - Method for preparing graphene quantum dots - Google Patents

Method for preparing graphene quantum dots Download PDF

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KR20170018129A
KR20170018129A KR1020150110565A KR20150110565A KR20170018129A KR 20170018129 A KR20170018129 A KR 20170018129A KR 1020150110565 A KR1020150110565 A KR 1020150110565A KR 20150110565 A KR20150110565 A KR 20150110565A KR 20170018129 A KR20170018129 A KR 20170018129A
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South Korea
Prior art keywords
graphene
aqueous solution
hydrogel
quantum dots
graphene quantum
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KR1020150110565A
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Korean (ko)
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KR101787826B1 (en
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김태성
진홍이
공타오
이창구
김은화
조유진
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성균관대학교산학협력단
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Priority to KR1020150110565A priority Critical patent/KR101787826B1/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
    • C09K11/65—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
    • C01B31/0446—
    • C01B31/0484—
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

The present invention relates to a method for producing graphene quantum dots (GQDs). According to the present invention, the method for producing the GQDs includes a step of putting graphene hydrogel, obtained by conducting hydrothermal treatment using graphene oxide, into an organic solvent. The method for producing the GQDs also enables the production of GQDs without post-treatment processes which require a long amount of time such as centrifugation, filtration, and dialysis.

Description

{METHOD FOR PREPARING GRAPHENE QUANTUM DOTS}

The present invention relates to a graphene quantum dot generating method, and more particularly, to a graphene quantum dot generating method in which graphene hydrogel produced by hydrothermal teatment of graphene oxide is put into an organic solvent to form graphene quantum dots, To a graphene quantum dot generating method capable of generating a graphene quantum dot by a simple method.

Quantum dots are nano-sized materials that can realize all the desired color light. Recently, researches for using quantum dots in various fields such as display and thin film solar cell have been actively conducted.

In recent years, research on the method of producing graphene quantum dots using graphite without heavy metals has been actively studied. Various methods for synthesizing graphene quantum dots have been reported. For example, a hydrothermal synthesis method, a solvothermal method, an electrochemistry method, a microwave method, and a bottom- And a bottom-up method. Among them, hydrothermal synthesis is a relatively simple method.

In the conventional hydrothermal synthesis method, graphene nanoparticles having a large size are present in a colloidal solution even after cutting a graphene sheet by hydrothermal treatment. These nanoparticles interfere with the photoluminescence of graphene quantum dots, and thus require further purification steps such as centrifugation, filtration, and dialysis. This purification process takes a long time.

Korean Patent Publication No. 10-2013-0050167

Accordingly, it is an object of the present invention to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method for producing graphene quantum dots by hydrothermally synthesizing graphene which does not require a long post- And a method of generating quantum dots.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

The object is achieved according to the invention by preparing an aqueous solution of graphene oxide; Hydrothermal treatment of the graphene oxide aqueous solution to produce graphene hydrogel and graphene quantum dots adsorbed on the graphene hydrogel; And separating the graphene quantum dots deposited on the surface of the graphene hydrogel by placing the graphene hydrogel in an organic solvent.

The step of forming the graphene hydrogel may include heating the graphene oxide aqueous solution in an autoclave at a temperature of 180 for 12 hours; And cooling the heated graphene oxide aqueous solution at room temperature.

The method may further include a step of ultrasonically treating the graphene oxide aqueous solution with an ultrasonic sonicator before the graphene oxide aqueous solution is heated in the autoclave.

Here, the ultrasonic mill is a probe type ultrasonic mill and is preferably subjected to ultrasonic treatment for 2 to 4 hours at a frequency of 15 kHz.

Here, the organic solvent may be at least one selected from the group consisting of tetrahydrofuran, acetone, ethanol, dichloromethane, ether, chloroform, toluene, hexane).

The method may further include removing graphene hydrogel from the organic solvent after separating the graphene quantum dots.

The graphene quantum dot generation method according to the present invention has an advantage that graphene quantum dots can be generated without a long post-treatment such as centrifugation, filtration, and dialysis.

1 is a flowchart of a graphene quantum dot generating method according to an embodiment of the present invention.
2 is a detailed flowchart of step S120 of FIG.
FIG. 3 is a graph showing a product produced during the formation of graphene quantum dots according to the present invention, together with photographs. FIG.
FIG. 4 is a view showing a graphene hydrogel in an aqueous solution in FIG. 3 (b). FIG.
FIG. 5 is a graph showing a graphene quantum dot and a graphene hydrogel separated by an organic solvent in FIG. 3 (c). FIG.
FIG. 6 shows photographs of graphene hydrogels contained in different organic solvents, wherein (a) is a photograph under visible light and (b) is a photograph under ultraviolet light having a wavelength of 365 nm.
7 is a high-resolution transmission electron microscope (HRTEM) image showing the size of the graphene quantum dot produced according to the present invention.
8 is a high-resolution transmission electron microscope (HRTEM) photograph showing the fringe pattern of graphene quantum dots generated according to the present invention.
9 (a) is an atomic force microscope (AFM) photograph showing graphene quantum dots produced according to the present invention, (b) is a view showing a height distribution of graphene quantum dots measured along line 1 of (a) to be.

Hereinafter, a graphene quantum dot generating method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. This is for the purpose of illustrating the present invention and is not intended to limit the scope of protection defined by the appended claims.

FIG. 1 is a flowchart of a graphene quantum dot generating method according to an embodiment of the present invention. FIG. 2 is a detailed flowchart of the step S120 of FIG. 1. FIG. Fig. 4 is a view showing the graphene hydrogel in the aqueous solution in Fig. 3 (b), Fig. 5 is a graph showing the graphene hydrogel in the aqueous solution phase in the Pin quantum dot and graphene hydrogel.

The graphene quantum dot generating method according to an embodiment of the present invention includes the steps of preparing an aqueous solution of graphene oxide (GO) (S110), hydrothermal treatment of an aqueous solution of graphene oxide (210) A graphene hydrogel 220 is formed on the surface of the graphene hydrogel 220 and a graphene hydrogel 220 is introduced into the organic solvent 240 to form graphene hydrogel 220, graphite quantum dots 230 in step S130. The method may further include a step (S140) of removing the graphene hydrogel 220 from which the graphene quantum dots 230 have been separated from the organic solvent 240.

First, graphite is oxidized for a long time to produce ultrafine graphene oxide 210 to prepare an aqueous solution of graphene oxide 210 (S110). A method for producing an aqueous solution of graphene oxide (210) can be various known methods. In the following experimental example, a method for producing an aqueous solution of graphene oxide (210) by the modified Hummer method will be described.

Experimental Example  ( Grapina Oxide (210) aqueous solution Experimental Example )

1. Mix 3 g of graphite powder, 2.5 g of sodium nitrate (NaNO 3 ) and 185 g of 95% sulfuric acid (H 2 SO 4 ) with a stirrer.

2. Cool the mixture in step 1 for 1 hour using an icewater bath.

3. Add 12 g of potassium permanganate (KMnO 4 ) slowly to the mixture.

4. Stir the mixture from step 3 for 4 days at room temperature.

5. 5wt% sulfuric acid (H 2 SO 4) was added to the aqueous solution of 300ml, stir for 1 hour.

6. Add 30wt% hydrogen peroxide (H 2 O 2 ) slowly until the color turns yellow and stir for 1 hour.

The mixture of 7.6 is centrifuged and washed with DI water to produce an aqueous solution of graphene oxide 210, wherein the concentration of the graphene oxide 210 aqueous solution is diluted to 2-4 mg / mL.

After the aqueous solution of graphene oxide 210 is formed by the above-described method and various known methods, the aqueous solution of graphene oxide 210 may be subjected to a hydrothermal treatment to produce graphene hydrogel 220. At the same time, the pieces of ultrafine graphene oxide 210 in the aqueous solution of graphene oxide 210 can be transformed into graphene quantum dots 230 by hydrothermal reduction treatment. That is, a reduced-graphene-oxide (rGO) hydrogel reduced by hydrothermal treatment is the graphene quantum dot 230 immediately.

At the water, the graphene quantum dot 230 is adsorbed to the surface of the graphene hydrogel 220 by p-p lamination. 3 (a) shows an aqueous solution of graphene oxide 210, and FIG. 3 (b) shows a state in which graphene hydrogel 220 is formed by hydrothermally treating an aqueous solution of graphene oxide 210 of (a) And graphene quantum dot 230 is adsorbed on the surface of graphene hydrogel 220 as shown in FIG. This is well illustrated in FIG.

A method of hydrothermally treating an aqueous solution of graphene oxide 210 is shown in FIG. 2. First, the aqueous solution of graphene oxide 210 is subjected to ultrasonic treatment using an ultrasonic wave sonicator (not shown) to be peeled off (S121). At this time, it is preferable to ultrasonify the probe type ultrasonic mill (not shown) at a frequency of 15 kHz for 2-4 hours.

Next, the ultrasonic treated graphene oxide aqueous solution 210 is placed in an autoclave (not shown) and heated at a temperature of 180 for 12 hours (S122).

Finally, the graphene hydrogel 220 can be formed by heating in an autoclave (not shown) and then cooling at room temperature (S123).

The method of hydrothermally treating an aqueous solution of graphene oxide 210 is not limited to the experimental conditions described above, but can be modified in accordance with the amount of graphene oxide aqueous solution, experimental environment, and the like.

Next, the graphene quantum dot 230 is adsorbed on the surface of the graphene hydrogel 220, and then the graphene quantum dot 230 is separated from the graphene hydrogel 220. More specifically, the graphene hydrogel 220 on the aqueous solution is immersed in the organic solvent 240 by using a tweezers (not shown) or the like, and after a predetermined time has elapsed, the graphene hydrogel 220, which has been adsorbed to the graphene hydrogel 220, The quantum dots 230 are separated into the organic solvent 240 (S130). When the graphene hydrogel 220 is immersed in the organic solvent 240, van der Waals forces interact between the organic solvent 240 and the graphene quantum dot 230 adsorbed on the graphene hydrogel 230 , Graphene quantum dots 230 adsorbed on the surface of the graphene hydrogel 220 can be easily separated.

As the organic solvent 240, it is preferable to use an organic solvent having a low polarity, such as tetrahydrofuran, acetone, ethanol, dichloromethane, ether, Any one of chloroform, toluene and hexane can be used.

FIG. 3 (c) shows that the graphene quantum dot 230 is separated by immersing the graphene hydrogel 220 in the organic solvent (hexane) 240. This is illustrated in more detail in FIG.

Finally, a graphene quantum dot solution 230 dissolved in an organic solvent can be obtained by removing the graphene hydrogel 220 separated from the graphene quantum dot 230 in FIG. 3 (c) (S140).

Grapina Quantum dot  Character analysis

Hereinafter, the characteristics of the graphene quantum dot 230 produced according to the present invention will be described with reference to FIGS. 6 to 9. FIG.

Fig. 6 shows photographs of graphene hydrogels contained in different organic solvents, in which (a) is a photograph under visible light, (b) is a photograph under ultraviolet light of 365 nm wavelength, and Fig. 7 (HRTEM) photograph showing the size of the graphene quantum dot 230, and FIG. 8 is a photograph of a high resolution transmission electron microscope (HRTEM) showing the fringe pattern of the graphene quantum dot produced according to the present invention (A) is an atomic force microscope (AFM) photograph showing graphene quantum dots produced according to the present invention, and FIG. 9 (b) is a height distribution of graphene quantum dots measured along line 1 of FIG.

6 shows a solution of graphene quantum dot 230 formed by immersing graphene hydrogel 220 in different organic solvents 240. From the left, organic solvent 240 is dissolved in tetrahydrofuran, acetone, ethanol , Dichloromethane, ether, chloroform, toluene and hexane were used. The graphene quantum dots generated according to the present invention have emission spectra of a blue series of between 340 nm and 430 nm (FIG. 5A). FIG. 6A is a photograph of visible light, FIG. 6B is a photograph of ultraviolet appear.

As shown in FIG. 7, the size of the graphene quantum dot 230 was less than 5 nm through the HRTEM photograph. 8 shows the interference fringes of graphene quantum dots. The lattice parameter, the distance between the centers of the interference fringes, was measured to be 0.22 nm. 9A shows the AFM image of the graphene quantum dot 230 and FIG. 9B shows the height distribution of the graphene quantum dot measured along the line 1 in FIG. The height of the graphene quantum dot 230 is distributed in a range of about 0.5 nm to 1.5 nm, and it can be seen that it is a monolayer graphene quantum dot.

The scope of the present invention is not limited to the above-described embodiments, but may be embodied in various forms of embodiments within the scope of the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

210: graphene oxide
220: graphene hydrogel
230: graphene quantum dots
240: organic solvent

Claims (6)

Preparing an aqueous solution of graphene oxide;
Hydrothermal treatment of the graphene oxide aqueous solution to produce graphene hydrogel and graphene quantum dots adsorbed on the graphene hydrogel; And
And introducing the graphene hydrogel into an organic solvent to separate graphene quantum dots deposited on the surface of the graphene hydrogel. The method according to claim 1,
The step of producing the graphene hydrogel comprises:
Placing the graphene oxide aqueous solution in an autoclave at a temperature of 180 for 12 hours; And
And cooling the heated graphene oxide aqueous solution at room temperature. 3. The method of claim 2,
The graphene oxide aqueous solution was added to the autoclave before heating
Further comprising the step of ultrasonically treating the graphene oxide aqueous solution with an ultrasonic sonicator. The method of claim 3,
Wherein the ultrasonic pulverizer is a probe type ultrasonic pulverizer and ultrasonically processed at a frequency of 15 kHz for 2 to 4 hours. The method according to claim 1,
The organic solvent may be selected from the group consisting of tetrahydrofuran, acetone, ethanol, dichloromethane, ether, chloroform, toluene, and hexane. The method comprising: The method according to claim 1,
After the step of separating the graphene quantum dots
And removing the graphene hydrogel from the organic solvent.
KR1020150110565A 2015-08-05 2015-08-05 Method for preparing graphene quantum dots KR101787826B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112267168A (en) * 2020-10-14 2021-01-26 浙江理工大学 Preparation method of high-strength photoluminescent hydrogel fiber

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20130050167A (en) 2011-11-07 2013-05-15 삼성전자주식회사 A method for manufacturing graphene quantum dot and graphene quantum dot manufactured by the same

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20130050167A (en) 2011-11-07 2013-05-15 삼성전자주식회사 A method for manufacturing graphene quantum dot and graphene quantum dot manufactured by the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112267168A (en) * 2020-10-14 2021-01-26 浙江理工大学 Preparation method of high-strength photoluminescent hydrogel fiber
CN112267168B (en) * 2020-10-14 2022-12-06 浙江理工大学 Preparation method of high-strength photoluminescent hydrogel fiber

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