KR101403534B1 - Method for manufacturing carbon quantum dots - Google Patents

Abstract

A carbon quantum dot is carbon nanoparticles showing quantum effects, which is chemically stable and does not have biological toxicity, thereby being able to replace semiconductor quantum dots. According to the present invention, a method of synthesizing carbon quantum dots by creating a condition similar to a natural environment where coal and graphite are produced is developed, and by using an accelerating agent, all kinds of organic matters are degraded, thereby synthesizing the carbon quantum dots. In addition, by using organic solvent, efficiency of synthesizing the carbon quantum dots can be significantly improved, therefore a mass synthesis method is suggested. By using the method of the present invention, the size of the carbon quantum dots can be easily adjusted and the synthesized carbon quantum dots have excellent fluorescence characteristics and high dispersibility to water.

Description

[0001] The present invention relates to a method for manufacturing carbon quantum dots,

The present invention relates to a carbon quantum dot manufacturing method and a carbon quantum dot manufactured thereby, and more particularly, A reaction promoter such as an organic compound such as sugar, starch, vitamin C, glucose, tartaric acid, citric acid, oleic acid, glutamine, glutamic acid, urea, benzene, acetylacetone, acetophenone, A method for producing a carbon quantum dots by mixing them in a solvent such as 2-propanol, hydrogen peroxide, n-propanol or chlorobenzene and reacting them in a sealed container at a temperature of 230 ° C or higher to produce carbon quantum dots, will be.

In solid state carbon, diamond, graphite (graphite) and amorphous coal exist in nature depending on crystal structure. Carbon nanotubes (CNTs), pululenes, and graphenes are well known as nano-sized carbon crystals. It is well known that carbon QDs are not pure carbon crystals but have physical properties of quantum effects in nanoscale carbon compounds and are applicable in various fields.

Carbon quantum dots (CQDs) are based on graphite nanoparticles and are known to have chemical groups such as epoxide, hydroxyl, and carboxyl groups on the surface. Carbon nanoparticles (carbon nanoparticles), graphene oxide It is also called nanoparticles. The main component of the carbon quantum dots is carbon (graphite nanoparticles) and has the characteristics of quantum dots. The size of the carbon quantum dots is several nm. It has a characteristic of quantum dots with a different color depending on the particle size, and the fluorescence wavelength varies depending on the particle size. It also emits fluorescence of different wavelengths according to the wavelength of the excitation light, and is easily mixed (dissolved) in water. Unlike semiconductor quantum dots, which are highly toxic, such as CdSe, carbon QDs are biocompatible carbon compounds and can be applied to sensors that can be injected into the human body.

Although carbon quantum dots are potentially applicable to many fields, chemical synthesis methods that can be mass produced are not well known. When one layer of graphite is peeled off, it becomes graphene. When graphite is crushed into nanoparticles, it becomes carbon quantum dots. The method of forming carbon quantum dots by stripping or grinding graphite is called top-down method and is the most common method of synthesizing carbon quantum dots.

When graphite is chemically decomposed, it becomes a carbon quantum dot, and laser ablation or electrooxidizing may be used. However, the method of producing carbon quantum dots by the top-down method has a low production efficiency, and it is very difficult to artificially control particle size, surface state, and the like.

Therefore, a new synthesis technique of a bottom-up method is required to overcome various disadvantages of existing methods of synthesizing carbon QDs.

US Publication No. 20120178099 (disclosed on July 12, 2012) US Publication No. 20110014630 (disclosed on January 20, 2011) US Registration No. 7829772 (Registration Notice for November 09, 2010)

In order to overcome various problems of existing methods for synthesizing carbon quantum dots as described above, the present invention can be applied to a bottom-up method which is a new synthesis technique, that is, a reaction for decomposing, Carbon quantum dots can be manufactured.

That is, the present invention aims to synthesize carbon quantum dots from all kinds of organic materials, and to control the size and efficiency of the products and to synthesize them in large quantities.

The above-mentioned object can be accomplished by mixing an organic compound, a solvent and an accelerator to form a solution; And a step of heating the solution.

According to an aspect of the present invention, the promoter is any one or more of an oxidizing agent, a reducing agent, and a catalyst.

According to another aspect of the present invention, the oxidant is at least one of nitric acid, sulfuric acid, and hydrogen peroxide.

According to still another aspect of the present invention, the reducing agent is potassium borohydride.

Further, according to still another aspect of the invention, the catalyst is Fe ₂ O ₃ Nanoparticles.

According to another aspect of the present invention, the solvent is at least one of water, methanol, ethanol, 2-propanol, n-propanol, hydrogen peroxide and chlorobenzene.

According to still another aspect of the present invention, there is provided a method for producing an organic compound, wherein the organic compound is selected from the group consisting of sugar, starch, vitamin C, glucose, tartaric acid, citric acid, oleic acid, glutamine, glutamic acid, urea, benzene, acetyl acetone, acetophenone, Or more.

According to another aspect of the present invention, the solution is heated to a temperature of 220 to 290 DEG C or more.

Thus, according to the present invention, the present invention is a method for synthesizing carbon quantum dots, introducing a new synthesis method that takes advantage of the natural environment in which coal or graphite is generated from organic materials, thereby achieving higher efficiency and productivity than conventional methods, Quantum dots can be produced in large quantities.

In addition, the present invention can control the size and synthesis efficiency of carbon quantum dots by simply changing synthesis conditions such as solvent and temperature.

In addition, the present invention can synthesize carbon quantum dots from almost all kinds of organic materials and can be synthesized from inexpensive food compounds such as wheat flour, starch, and sugar.

In addition, since the present invention synthesizes carbon quantum dots only with solvents, accelerators, and organic substances, carbon quantum dots can be obtained from the synthesized products without complicated purification steps.

In addition, the present invention includes a crystallization process. In the crystallization process, the size of the product can be controlled according to the concentration of the organic substance. When the concentration of the organic substance is high, large particles are produced.

The present invention also relates to a method of synthesizing carbon quantum dots by a bottom-up method for decomposing organic compounds to synthesize carbon quantum dots, thereby improving efficiency and economy, facilitating control of particle size, uniformizing the particle size of carbon quantum dots And the physical properties thereof are uniform.

Figures 1 to 54 show the results of various embodiments of carbon quantum dots synthesized by the method of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

end. Generation of carbon isotopes in nature

Coal, graphite, and diamond are carbon isotopes. Diamonds are carbon crystals formed under high temperature and high pressure conditions and are mainly found in the igneous rocks. Graphite is mainly found in metamorphic rocks and may be found in igneous rocks. It is known that coal, which is carbonless, is mainly found in sedimentary rocks, and the sedimentary layers of organic matter in plants and animals are carbonized through oxidation and carbonization. Diamonds, graphite, and coal, all of which are made in nature, are produced from organic matter in a situation where pressure and temperature are given constantly. Amorphous coal is produced in sediments with low pressure and temperature. Layered graphite is formed in the metamorphic rock layer with medium pressure and temperature, and high hardness diamond is formed in the high temperature and high pressure igneous rock layer.

I. Of carbon nanoparticles  Crystal growth

It is believed that carbon materials can be produced by artificially conditioning the conditions under which carbon crystals are produced. The carbon quantum dots have a lower crystallinity than graphite, which is a lump crystal, and have a higher degree of crystallinity than that of seamless carbon. It is believed that carbon quantum dots, which are carbon materials with low crystallinity, can be produced by setting up an environment having a temperature and pressure intermediate between the environment in which coal is produced and the environment in which graphite is produced. Carbon quantum dots are formed when organic matter decomposes in the environment of such temperature and pressure, is carbonized and crystallizes into nanoparticles.

Hydrothermal methods or similar solvothermal methods can be used to create the pressure and temperature at which sedimentary and metamorphic rocks are formed. In the hydrothermal synthesis method, a sealed vessel with water is heated to produce temperature and pressure, and crystals such as crystal, emerald and ZnO can be grown. Solvent thermo-synthesis is a method of synthesizing by heating and heating a sealed container containing an organic solvent such as alcohol and benzene to produce an organic solvent.

All. accelerant

Organic matter (carbon compound) buried underground is slowly decomposed and carbonized to produce coal. The natural process of producing coal requires not only heat and pressure to decompose and carbonize organic matter, but also a long time. However, in order to decompose and carbonize organic matter artificially, an active method for decomposing organic matter is required. In the present invention, the decomposition of organic matter is promoted by using an oxidizing agent, a reducing agent, a catalyst, and the like. Examples of the reducing agent include NaBH ₄ , potassium borohydride (KBH ₄ ), LiAlH ₄ , N ₂ H _4, etc. As the catalyst, platinum, Pd , Ni, TiO ₂ , and Fe ₂ O ₃ nanoparticles.

la. Organic matter

Coal, graphite, etc. are produced by decomposition and carbonization of organic matter, which is the remnant of plants and animals. In the present invention, general organic compounds are used as starting materials for synthesizing carbon quantum dots. They are organic products extracted from plants, such as white sugar, starch, ascorbic acid, glucose, tartaric acid, citric acid, oleic acid, , Glutamine, glutamic acid and urea, benzene, acetylacetone, acetophenone (C ₆ H ₅ C (O) CH ₃ ), acetic acid, The carbon quantum dots can be synthesized from all types of organic materials. All of these organics are either transparent liquids or white powders. When a transparent or white organic material is used as a starting material and synthesized by the method of the present invention, it becomes a liquid having a color unique to a carbon quantum dot, and when the concentration of carbon quantum dots is high, it becomes a black liquid.

hemp. menstruum

In solvothemal crystal growth, it is possible to control the rate and shape of crystal growth depending on the polarity of the solvent. In the present invention, the shape of carbon crystals was controlled according to the dielectric constant of the solvent. It is easy to synthesize low-concentration carbon quantum dots by using water, which is a polar solvent. When the polarity of the solvent is low, a high concentration of carbon quantum dots can be synthesized, thereby increasing the efficiency of synthesis. In the present invention, a solvent such as water, methyl alcohol, ethyl alcohol, 2-propanol alcohol, n-propyl alcohol, hydrogen peroxide and chlorobenzene is used To synthesize carbon quantum dots.

In the present invention, a method of synthesizing carbon quantum dots by decomposing, carbonizing and crystallizing an organic material has been developed, and a flow chart of this method is as follows. Through the method of the present invention, it is possible to decompose all kinds of organic materials to synthesize carbon quantum dots. In addition, the synthesis efficiency of the carbon quantum dots is high and it is possible to control the size.

Carbon isotopes such as coal, graphite, and diamond are generated by heat and pressure in the crust. The raw materials of coal and graphite are organic matter, organic compounds buried in the crust are decomposed, carbonized and crystallized, and carbon isotopes are produced. In the present invention, a principle of naturally occurring carbon isotopes is borrowed, and a new synthesis method for synthesizing carbon quantum dots has been developed. This synthesis process consists of decomposing organic compounds dissolved in a closed container using accelerators and carbonizing and decomposing the decomposed organic compounds under pressure and heat.

This synthesis method includes (i) a high-pressure reactor capable of maintaining high-temperature and high-pressure conditions, (ii) various organic compounds as raw materials, (iii) accelerators for decomposing organic substances and promoting the reaction, and ) Reaction was used. When the synthesis method of the present invention is used, it is possible to synthesize carbon quantum dots by using all kinds of organic substances as precursors.

(i) The high-pressure reactor used in the synthesis of the present invention is composed of an inner vessel and an outer vessel as in the registered patent 1007694210000. The inner vessel is made of Teflon which does not react with chemicals, and the outer vessel for maintaining pressure is made of stainless steel Respectively. A temperature controller and a magnetic stirrer were attached to the high pressure reactor. The temperature of the chemical reaction was automatically controlled using a thermostat, and the solution was kept homogeneous during the reaction using a magnetic stirrer. There are two types of high-pressure reactors used in the reaction, and the volume of each inner container is 1,200 cc and 60 cc.

(ii) In the present invention, carbon quantum dots were synthesized from various organic compounds, and the organic compounds used in the invention Starch, vitamin C, glucose, tartaric acid, citric acid, glutamine, glutamic acid, and the like, and the like. The greatest advantage of the synthesis method of the present invention is that carbon nanoparticles can be synthesized from almost all kinds of organic materials by decomposing organic compounds that can be contacted and carbonizing them.

(iii) In nature, organic compounds slowly decompose over time. However, in the present invention, an oxidizing agent, a reducing agent, a catalyst, and the like are added to the chemical reaction to accelerate the decomposition of the organic compound and facilitate the synthesis of carbon quantum dots.

(iv) In the present invention, various solvents such as water, methanol, alcohol, propanol, and chlorobenzene were used to control the reaction. When water was used as a solvent, the concentration of carbon QDs was low. When the solvent was methanol, alcohol, propanol, chlorobenzene, etc., the amount of synthesized carbon quantum dots increased greatly.

bar. Purification of compounds

Organic compounds such as solvent, carbon quantum dots, aromatic oil, and precipitates were contained in the synthesized compound by the method of the present invention, and their physical and chemical properties were evaluated by refining them. Carbon quantum dots are readily soluble in water and are several nm in size. When the precipitate is removed from the composite and filtered several times with a hydrophilic paper filter, the directional oil is filtered by the filter and the carbon quantum dots and the solvent are permeated. The permeated solution was diluted with water and passed through a hydrophilic membrane filter having a pore size of 0.1 mu m to obtain a carbon quantum dot solution. The carbon quantum dots solution, which was purified by removing the impurities, was uniform and the dispersion was very good in water such as no precipitation even after 3 months at room temperature.

four. Carbon quantum dot of  evaluation

As is well known in the analysis methods for carbon QDs, there are various methods such as XRD pattern, FT-IR absorption spectrum, particle size measurement by TEM, fluorescence characteristic, and light absorption characteristic. The most important feature of carbon QDs is the carbon material that emits fluorescence. In the present invention, four fluorescence measurement results are shown for one synthetic example. Two fluorescence images taken from the bottom of the solution vial and two fluorescence spectra measured with a fluorescence spectrophotometer. The fluorescence spectra of the two fluorescence spectra were measured by irradiating light of 365 nm and 400 nm, respectively, and the color coordinates (CIE1931) of the fluorescence were calculated from the measured fluorescence spectra.

Since the main component of the carbon QD is carbon, it absorbs light in all wavelength regions of visible light. In the present invention, the types and quantities of organic materials, the synthesis temperatures, the times, the types of solvents, and the kinds of accelerators were synthesized, respectively. The solution containing the carbon quantum dots was extracted from the composite and placed in a cuvette having a transmission length of 10 mm to measure a light absorption spectrum in the range of 300 nm to 700 nm. The absorbance of 500 nm in the measured light absorption spectrum was expressed in terms of optical density (OD) to compare the synthesis efficiency of the carbon quantum dots.

The combined conditions and the absorption of the composite are shown in Tables 1 and 2. The amounts of carbon QDs produced by the different solvents were increased in the order of water, methanol, and ethanol, while maintaining the same reaction conditions such as the kind and amount of organic compounds, reaction promoter, and temperature. As shown in <Synthesis Example 2>, when OD is 0.185 when water is used as a solvent and OD is 1.94 when methanol is used as a solvent in <Synthesis Example 20>, Synthesis Example 29 &Gt; is OD 6.24. As shown in Tables 1 and 2, the concentration of carbon quantum dots synthesized in ethanol is several orders of magnitude larger than that of carbon quantum dots synthesized using water as a solvent. 5 cc of the solution synthesized by the method of <Synthesis Example 31> was diluted with water to obtain 500 cc of a carbon quantum dope solution having the same concentration as that of <Synthesis Example 2>.

Studies reported on the synthesis of carbon quantum dots in the bottom-up method have shown that synthesis efficiency is low using hydrothermal synthesis, primarily using water as a solvent. However, in the present invention, the efficiency of synthesis of carbon quantum dots using an organic solvent such as methanol or ethanol is improved, and a synthesis method capable of mass-producing carbon quantum dots by decomposing almost all kinds of organic substances by facilitating reaction using an accelerator .

Ah. Examples of synthesis

Examples of synthesis of carbon quantum dots are summarized in Tables 1 and 2 below. The type and amount of organic compounds, reaction promoters, and solvents used to synthesize the carbon QDs are shown, and the reaction temperature and duration are also shown. In the synthesis example, when the amount of the solvent was less than 60 cc, the synthesis was carried out using a high-pressure reactor having an internal volume of 60 cc and a synthesis in which the amount of the solvent was more than 400 cc was performed using a high-pressure reactor having an internal volume of 1200 cc. In addition, the absorbance of the reaction solution was measured to compare the relative concentrations of the generated carbon quantum dots.

Synthetic example Organic matter / g Solvent / cc Accelerator / g Temperature / ℃ Hour / hr Absorption / OD One acetylacetone / 36 H ₂ O / 500 HNO _3/12 250 30 0.194 2 acetylacetone / 3 H ₂ O / 37.5 HNO _3/1 250 35 0.185 3 citric acid / 36 H ₂ O / 500 HNO _3/12 250 30 0.939 4 citric acid / 3 H ₂ O / 40 HNO _3/1 250 35 0.0304 5 glucose / 1 H ₂ O / 37.5 HNO _3/3 245 30 0.0096 6 glucose / 1.2 H ₂ O / 37.5 HNO _3/2 245 30 0.117 7 sugar / 1.4 H ₂ O / 37.5 HNO _3/3 250 30 0.130 8 sugar / 3 H ₂ O / 37.5 HNO _3/1 245 30 0.564 9 starch / 3 H ₂ O / 37.5 HNO _3/1 250 30 0.410 10 acetic acid / 3 H ₂ O / 37.5 HNO _3/2 245 24 0.00475 11 tartar acid / 2 H ₂ O / 37.5 HNO _3/2 245 30 0.0789 12 urea / 3 H ₂ O / 37.5 HNO _{3 /} 1.3 245 30 0.00147 13 glutamic acid / 1 H ₂ O / 37.5 HNO _3/1 245 30 0.123 14 oleic acid / 3 H ₂ O / 37.5 HNO _3/1 250 30 0.0385 15 acetophenone / 3 H ₂ O / 37.5 HNO _3/1 245 30 0.111 16 acetylacetone / 3 H ₂ O _{2 /} 37.5 - 245 30 0.197 17 glucose / 3 H ₂ O / 37.5 H ₂ SO _4/1 245 30 0.170 18 acetylacetone / 3 H ₂ O / 37.5 KBH _4/1 245 30 0.480 19 acetylacetone / 36 MeOH / 500 HNO _3/12 250 30 3.62 20 acetylacetone / 3 MeOH / 37.5 HNO _3/1 250 35 1.94 21 acetylacetone / 3 H ₂ O / 20
MeOH / 20 HNO _3/1 250 35 0.679 22 acetone / 3 MeOH / 37.5 HNO _3/1 250 30 1.52 23 acetophenone / 3 MeOH / 37.5 HNO _3/1 250 30 1.01 24 oleic acid / 3 MeOH / 37.5 HNO _3/1 250 30 0.254 25 acetylacetone / 36 EtOH / 550 HNO _3/12 250 35 5.25 26 acetylacetone / 3 EtOH / 45 HNO _{3 /} 0.451 250 35 2.22 27 acetylacetone / 3 EtOH / 45 HNO _{3 /} 0.452 230 35 1.16

Synthetic example Organic matter / g Solvent / cc Accelerator / g Temperature / ℃ Hour / hr Absorption / OD 28 acetylacetone / 3 EtOH / 53 HNO _{3 /} 0.454 280 35 1.31 29 acetylacetone / 3 EtOH / 37.5 HNO _3/1 250 35 6.24 30 acetylacetone / 9 EtOH / 20 HNO _3/3 250 30 58.6 31 acetylacetone / 15 EtOH / 20 HNO _3/5 250 20 75.1 32 acetylacetone / 3 EtOH / 45 HNO _{3 /} 0.45 250 35 0.345 33 ascorbic acid / 3 EtOH / 40 HNO _3/1 250 35 25.6 34 ascorbic acid / 9 EtOH / 20 HNO ₃ /3.24 250 30 36.3 35 glutamine / 3 EtOH / 37.5 HNO _3/1 250 30 6.51 36 glucose / 1 EtOH / 37.5 HNO _3/3 245 30 25.9 37 sugar / 1 EtOH / 37.5 HNO _3/3 250 30 27.5 38 sugar / 15 EtOH / 20 HNO _3/5 245 30 20.1 39 sugar / 3 EtOH / 37.5 HNO _3/1 245 30 22.4 40 tartar acid / 3 EtOH / 37.5 HNO _3/1 245 30 4.30 41 urea / 3 EtOH / 45 HNO _3/1 245 30 1.66 42 acetone / 3 EtOH / 37.5 HNO _3/1 245 30 1.56 43 ethyleneglycolate / 3 EtOH / 37.5 HNO _3/1 245 30 3.78 44 starch / 3 EtOH / 37.5 HNO _3/1 250 30 39.1 45 oleic acid / 3 EtOH / 45 HNO _{3 /} 0.157 250 35 0.650 46 acetylacetone / 3 2-PrOH / 40 HNO _3/3 250 35 4.27 47 acetylacetone / 3 n-PrOH / 37.5 HNO _3/1 250 30 5.28 48 acetylacetone / 3 chlorobenzene / 37.5 HNO _3/1 245 30 20.5 49 glucose / 3 EtOH / 37.5 H ₂ SO _4/1 245 30 1.423 50 sugar / 1 EtOH / 40 KBH _4/1 245 30 10.6 51 acetylacetone / 3 EtOH / 37.5 KBH _4/1 245 30 3.94 52 benzene / 3 EtOH / 37.5 KBH ₄ /0.685 245 30 1.56 53 acetylacetone / 3 EtOH / 45 Fe ₂ O ₃ /0.3 250 35 0.0467 54 acetylacetone / 3 EtOH / 42.5 CH ₃ COOH / 0.5 250 35 0.0173

character. Describe the picture of synthesis and analysis results

The results of summarizing the characteristics of various embodiments of carbon quantum dots synthesized by the method of the present invention are shown in FIGS. 1 to 54. Figs. 1 to 54 show the result characteristics of various examples synthesized by the methods of < Synthesis Examples 1 to 54 as shown in Tables 1 and 2.

1, that is, FIGS. 1A to 1I are the results of summarizing the characteristics of Synthesis Example 1 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 1 of Table 1, 500 cc of distilled water, 36 g of acetylacetone, And the mixture was placed in a high-pressure reactor having an internal volume of 1200 cc and reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in Figure 1 (a). As shown in FIG. 1 (a), absorption occurs in all the wavelength regions of visible light, and the intensity of absorption gradually increases as the wavelength is shortened. At 261 nm, a peak of the absorption curve appears, which is an optical band that is one of the characteristics of the carbon quantum dots. The absorption coefficient of the synthesis solution at 500 nm is 0.194. Fig. 1 (b) shows an excitation spectrum when the fluorescence wavelength is 428 nm. In this excitation spectrum, it is also found that there is an optical band having the same wavelength as the absorption spectrum. The fluorescence spectrum when irradiated with excitation light of 365 nm is shown in Fig. 1 (c).

One of the characteristics of the carbon quantum dots is that the fluorescence spectrum varies depending on the excitation wavelength. As shown in FIG. 1 (d), when the excitation light has wavelengths of 335 nm, 365 nm, 435 nm, 470 nm and 500 nm, respectively, the fluorescence spectrum is shown in FIG. 1 (d). (D-1) of FIG. 1, and the fluorescence emitted by irradiating the ultraviolet LED (380 nm) from the lower side of the glass bottle containing the solution is shown in (d- 2), and the photograph of the fluorescent light irradiated with the blue LED (460 nm) is (d-3) in FIG.

The FT-IR spectrum of the synthesized solution is shown in FIG. 1 (e). In the IR spectrum, absorption peaks due to OH, CH, C = O, CO and COC bonds can be confirmed. From these absorption peaks, it is estimated that chemical groups such as -COOH, -OH and = O are attached to the surface of the carbon quantum dots. can do. When the synthesized solution is dried, it becomes a sticky black gel. The x-ray diffraction pattern of the gel is shown in (f) of FIG.

1 (g) - (p). The size, shape, crystal lattice, etc. of the carbon quantum dots contained in the solution were confirmed by a transmission electron microscope (TEM). 1 (g) and 1 (i), the size of the carbon quantum dots was measured. The size distribution of the carbon quantum dots is shown in (q) of FIG. 1, and the average size of the carbon quantum dots is about 2.64 nm. Figs. 1 (h) and 1 (j) are TEM images obtained by partially enlarging (g) and (i) in Fig. 1, and a crystal surface pattern of carbon quantum dots appears as shown in the photograph. 1 (k) is a photograph of a carbon quantum dots with a definite crystal pattern, and FIG. 1 (1) shows a diffraction pattern of the crystal pattern. The diffraction point of FIG. 1 (1) has hexagonal symmetry and is equal to the symmetry of the c-plane of graphite. In FIGS. 1 (m) and (n), the diffraction pattern of the crystal face pattern and the hexagonal symmetry can be seen. In FIGS. 1 (o) and (p), the intervals between crystal faces were measured and compared with that of graphite.

1 (a) to 1 (p), the particles synthesized by the method of Synthesis Example 1 are graphite particles having an average size of 2.64 nm, and -COOH, -OH, and = O groups are attached And it is a carbon QD point showing the fluorescence characteristic of the quantum dot.

2 shows the results of summarizing the characteristics of Synthesis Example 2 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 2 shown in Table 1, 37.5 cc of distilled water, 3 g of acetylacetone and 1 g of nitric acid were mixed, And the reaction was carried out at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 2 (a), and the absorption coefficient at 500 nm is 0.185. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 2 (b) and 2 (c), respectively, and the fluorescence color coordinates are (0.1667, 0.1464) and (0.1883, 0.2455), respectively. 2 (d) is a photograph of a test tube containing the synthesized solution. 2 (e) shows a fluorescence image taken by irradiating and emitting ultraviolet LED (380 nm) from a lower part of a vial containing a solution, and a photograph taken with a blue LED (460 nm) (f).

3 shows the results of summarizing the characteristics of Synthesis Example 3 of the carbon quantum dots synthesized by the method of the present invention. In Synthesis Example 3 of Table 1, 500 cc of distilled water, 36 g of citric acid and 12 g of nitric acid were mixed, The reaction was carried out at 250 ° C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 3 (a), and the absorption coefficient at 500 nm is 0.937. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 3 (b) and 3 (c), respectively, and the fluorescence color coordinates are (0.1811, 0.1901) and (0.2006, 0.2883), respectively. 3 (d) is a photograph of a test tube containing the synthesized solution. FIG. 3 (e) shows a fluorescence image taken by irradiation with ultraviolet LED (380 nm) from the bottom of a glass bottle containing the solution, and FIG. 3 (f) to be.

4 shows the results of summarizing the characteristics of Synthesis Example 4 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 4 of Table 1, 40 cc of distilled water, 3 g of citric acid and 1 g of nitric acid were mixed, Lt; / RTI &gt; for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 4 (a), and the absorption coefficient at 500 nm is 0.0304. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are as shown in FIGS. 4 (b) and 4 (c), respectively, and the fluorescence color coordinates are (0.1677, 0.1462) and (0.2001, 0.2668), respectively. 4 (d) is a photograph of a test tube containing the synthesized solution. (E) of FIG. 4 (e) is a photograph of the fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of the glass bottle containing the solution, and FIG. to be.

5 shows the results of summarizing the characteristics of the carbon quantum dots synthesized by the method of the present invention. In the case of the synthesis example 5 of Table 1, 37.5 cc of distilled water, 1 g of glucose and 3 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 5 (a), and the absorption coefficient at 500 nm is 0.0096. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 5 (b) and 5 (c), respectively, and the fluorescence color coordinates are (0.1716, 0.1200) and (0.2841, 0.2670), respectively. 5 (d) is a photograph of a test tube containing the synthesized solution. FIG. 5E shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing the synthesized solution, FIG. 5E shows a fluorescence image taken with a blue LED (460 nm) f).

6 shows the results of summarizing the properties of Synthesis Example 6 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 6 shown in Table 1, 37.5 cc of distilled water, 1.2 g of glucose and 2 g of nitric acid were mixed, And reacted at 245 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 6 (a), and the absorption coefficient at 500 nm is 0.117. The fluorescence spectra measured by excitation with the light of 365 nm and 400 nm are shown in FIGS. 6 (b) and 6 (c), respectively, and the fluorescence color coordinates are (0.1659, 0.1590) and (0.1812, 0.2772), respectively. 6 (d) is a photograph of a test tube containing the synthesized solution. 6 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the synthesized solution, and FIG. 6 f).

7 shows the results of summarizing the characteristics of Synthesis Example 7 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 7 of Table 1, 37.5 cc of distilled water, 1 g of sugar and 3 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 7 (a), and the absorption coefficient at 500 nm is 0.130. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 7 (b) and 7 (c), respectively, and the fluorescence color coordinates are (0.1641, 0.1479) and (0.1777, 0.2546), respectively. 7 (d) is a photograph of a test tube containing the synthesized solution. 7 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the synthesized solution, and FIG. 7 f).

8 shows the results of summarizing the characteristics of Synthesis Example 8 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 8 of Table 1, 37.5 cc of distilled water, 3 g of sugar and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 8 (a), and the absorption coefficient at 500 nm is 0.564. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 8 (b) and 8 (c), respectively, and the fluorescence color coordinates are (0.1827, 0.1922) and (0.1843, 0.2843), respectively. 8 (d) is a photograph of a test tube containing the synthesized solution. FIG. 8 (e) is a photograph showing fluorescence emitted by irradiating ultraviolet LED (380 nm) from below the glass bottle containing the synthesized solution, and FIG. 8 f).

9 shows the results of summarizing the characteristics of the carbon quantum dot synthesized in the method of the present invention. In the case of the synthesis example 9 of Table 1, 37.5 cc of distilled water, 3 g of starch and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 9 (a), and the absorption coefficient at 500 nm is 0.410. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 9 (b) and 9 (c), respectively, and the fluorescence color coordinates are (0.1724, 0.1692) and (0.1826, 0.2729), respectively. 9 (d) is a photograph of a test tube containing the synthesized solution. 9 (e) shows a fluorescence image taken by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the synthesized solution, and FIG. 9 f).

10 shows the results of summarizing the characteristics of Synthesis Example 10 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 10 of Table 1, 37.5 cc of distilled water, 3 g of acetic acid and 2 g of nitric acid were mixed, Lt; 0 &gt; C for 24 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 10 (a), and the absorption coefficient at 500 nm is 0.00475. Fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 10 (b) and (c), respectively. 10 (b) is (0.1769, 0.1340), and FIG. 10 (c) corresponds to the case where the fluorescence is very weak, so that the color coordinates are not calculated. 10 (d) is a photograph of a test tube containing the synthesized solution. (E) of FIG. 10 (c) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution, and FIG. to be.

11 is a summary of the characteristics of Synthesis Example 11 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 11 of Table 1, 37.5 cc of distilled water, 2 g of tartaric acid and 2 g of nitric acid were mixed, For 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 11 (a), and the absorption coefficient at 500 nm is 0.0787. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 11 (b) and (c), respectively, and the fluorescence color coordinates are (0.1682, 0.1450) and (0.0.1906, 0.2529), respectively. 11 (d) is a photograph of a test tube containing the synthesized solution. FIG. 11 (e) is a photograph showing fluorescence emitted by irradiating ultraviolet LED (380 nm) from below the glass bottle containing the synthesized solution, and FIG. 11 f).

12 shows the results of summarizing the properties of Synthesis Example 12 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 12 of Table 1, 37.5 cc of distilled water, 3 g of urea and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 12 (a), and the absorption coefficient at 500 nm is 0.00147. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 12 (b) and 12 (c), respectively, and the fluorescence color coordinates are (0.1637, 0.1167) and (0.1899, 0.2526), respectively. 12 (d) is a photograph of a test tube containing the synthesized solution. FIG. 12 (e) shows a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from below the glass bottle containing the synthesized solution, and FIG. 12 f).

13 shows the results of summarizing the characteristics of Synthesis Example 13 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 13 of Table 1, 37.5 cc of distilled water, 1 g of glutamic acid and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 13 (a), and the absorption coefficient at 500 nm is 0.123. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are as shown in FIGS. 13 (b) and 13 (c), respectively, and the fluorescence color coordinates are (0.1653, 0.1215) and (0.2062, 0.2454), respectively. 13 (d) is a photograph of a test tube containing the synthesized solution. FIG. 13 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing the synthesized solution, and FIG. 13 f).

14 shows the results of summarizing the characteristics of Synthesis Example 14 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 14 shown in Table 1, 37.5 cc of distilled water, 3 g of oleic acid and 1 g of nitric acid were mixed and placed in a high- And reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 14 (a), and the absorption coefficient at 500 nm is 0.0384. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 14 (b) and 14 (c), respectively, and the fluorescence color coordinates are (0.1622, 0.1136) and (0.0.1740, 0.1967), respectively. 14 (d) is a photograph of a test tube containing the synthesized solution. FIG. 14 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing the synthesized solution, and FIG. 14 f).

15 is a summary of the properties of Synthesis Example 15 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 15 shown in Table 1, 37.5 cc of distilled water, 3 g of acetophenone and 1 g of nitric acid were mixed and placed in a high- And reacted at 245 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 15 (a), and the absorption coefficient at 500 nm is 0.111. Fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 15 (b) and (c), respectively. The color coordinates of FIG. 15 (b) are (0.2401, 0.2271), and FIG. 15 (c) corresponds to the case where the fluorescence is very weak. 15 (d) is a photograph of a test tube containing the synthesized solution. (E) of FIG. 15 (b) is a photograph showing fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution, and FIG. to be.

16 shows the results of summarizing the characteristics of the synthesis example 16 of the carbon quantum dots synthesized by the method of the present invention. In the case of the synthesis example 16 of Table 1, 37.5 cc of hydrogen peroxide and 3 g of acetylacetone were mixed and put into a high- The reaction was continued for 30 hours. In this synthesis, hydrogen peroxide, which is an oxidizing agent, is also a solvent and is an accelerator that accelerates the reaction by decomposing acetylacetone. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 16 (a), and the absorption coefficient at 500 nm is 0.197. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 16 (b) and 16 (c), respectively, and the fluorescence color coordinates are (0.1684, 0.1393) and (0.1854, 0.2287), respectively. 16 (d) is a photograph of a test tube containing the synthesized solution. FIG. 16 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution, and FIG. 16 (f) to be.

17 shows the results of summarizing the characteristics of Synthesis Example 17 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 17 of Table 1, 37.5 cc of distilled water, 3 g of glucose and 1 g of sulfuric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 17 (a), and the absorption coefficient at 500 nm is 0.170. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 17 (b) and 17 (c), respectively, and the fluorescence color coordinates are (0.1685, 1425) and (0.2144, 0.3331), respectively. 17 (d) is a photograph of a test tube containing the synthesized solution. FIG. 17 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from below the glass bottle containing the synthesized solution, and FIG. 17 f).

18 shows the results of summarizing the characteristics of Synthesis Example 18 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 18 of Table 1, 37.5 cc of distilled water, 3 g of acetylacetone, 3 g of potassium borohydride (KBH ₄ ) Were added to the autoclave and reacted at 245 ° C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 18 (a), and the absorption coefficient at 500 nm is 0.480. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 18 (b) and 18 (c), respectively, and the fluorescence color coordinates are (0.1910, 0.1899) and (0.2109, 0.3193), respectively. 18 (d) is a photograph of a test tube containing the synthesized solution. FIG. 18 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from below the glass bottle containing the synthesized solution, and FIG. 18 f).

19, that is, Figs. 19A to 19D are the results of summarizing the characteristics of Synthesis Example 19 of the carbon quantum dots synthesized by the method of the present invention. In Synthesis Example 19 of Table 1, 500cc of methanol, 36g of acetylacetone, The mixture was placed in a high-pressure reactor having an internal volume of 1200 cc and reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/15 ratio of the synthesis solution is shown in FIG. 19 (a), and the absorption coefficient at 0.25 nm is 0.241. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 3.62. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 19 (b) and 19 (c), respectively, and the fluorescence color coordinates are (0.1776, 0.1763) and (0.1964, 0.2739), respectively. 19 (d) is a photograph of a test tube containing the synthesized solution. FIG. 19 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/15 ratio solution, and FIG. 19 19 (f).

A TEM photograph of the synthesis solution is shown in Figure 19 (g). In the TEM photographs measured at a scale of 50 nm, the quantum dot particles that were not agglomerated could be seen, and the crystal lattice plane was clear in the five photographs in which each particle was enlarged. The average size of the quantum dot particles measured in the TEM photograph is 4.15 nm, and the distribution according to the size is shown in FIG. 19 (h). The FT-IR spectrum of the synthesized solution is shown in Fig. 19 (i). In the IR spectrum, absorption peaks due to OH, CH, C = O, CO, and COC bonds can be confirmed. It can be presumed that a chemical group such as -COOH, -OH and ═O is attached to the surface of the carbon quantum dots.

20 shows the results of summarizing the characteristics of Synthesis Example 20 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 20 of Table 1, 37.5 cc of methanol, 3 g of acetylacetone and 1 g of nitric acid were mixed, And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at 1/15 ratio is shown in FIG. 20 (a), and the absorption coefficient at 500 nm is 0.129. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.94. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 20 (b) and 20 (c), respectively, and the fluorescence color coordinates are (0.1768, 0.1754) and (0.1939, 0.2716), respectively. 20 (d) is a photograph of a test tube containing the synthesized solution. FIG. 20 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/15 ratio solution, and FIG. 20 20 (f).

21 shows the results of summarizing the characteristics of Synthesis Example 21 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 21 of Table 1, 20 cc of methanol, 20 cc of distilled water, 3 g of acetylacetone and 1 g of nitric acid were mixed, And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at 1/5 ratio is as shown in FIG. 21 (a), and the absorption coefficient at 500 nm is 0.136. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 0.679. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 21 (b) and 21 (c), respectively, and the fluorescence color coordinates are (0.1708, 0.1534) and (0.1962, 0.2784), respectively. 21 (d) is a photograph of a test tube containing the synthesized solution. 21 (e) shows a fluorescence image taken by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted at 1/5 ratio, and FIG. 21 21 (f).

22 shows the results of summarizing the properties of Synthesis Example 22 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 22 of Table 1, 37.5 cc of methanol, 3 g of acetone and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with a 1/10 ratio of the synthesis solution is shown in FIG. 22 (a), and the absorption coefficient at 500 nm is 0.152. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.52. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 22 (b) and 22 (c), respectively, and the fluorescence color coordinates are (0.1722, 0.1671) and (0.1848, 0.2632), respectively. 22 (d) is a photograph of a test tube containing the synthesized solution. FIG. 22 (e) is a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/10 ratio solution, and FIG. 22 (F) of FIG.

23 shows the results of summarizing the properties of Synthesis Example 23 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 23 of Table 1, 37.5 cc of methanol, 3 g of acetophenone and 1 g of nitric acid were mixed and placed in a high- And reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/7 ratio of the synthesis solution is shown in FIG. 23 (a), and the absorption coefficient at 500 nm is 0.144. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.01. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 23 (b) and (c), respectively, and the fluorescence color coordinates are (0.1689, 0.1111) and (0.2016, 0.2659), respectively. 23 (d) is a photograph of a test tube containing the synthesized solution. FIG. 23 (e) shows a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution diluted at 1/7 ratio, and FIG. 23 23 (f).

24 shows the results of summarizing the properties of Synthesis Example 24 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 24 of Table 1, 37.5 cc of methanol, 3 g of oleic acid and 1 g of nitric acid were mixed, And reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 24 (a), and the absorption coefficient at 500 nm is 0.254. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 24 (b) and 24 (c), respectively, and the fluorescence color coordinates are (0.1836, 0.1137) and (0.2038, 0.2861), respectively. 24 (d) is a photograph of a test tube containing the synthesized solution. FIG. 24 (e) shows a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the diluted solution at 1/7 ratio, and FIG. 24 24 (f).

25, that is, Figs. 25A to 25E are the results of summarizing the characteristics of Synthesis Example 25 of carbon quantum dots synthesized by the method of the present invention, and in the case of Synthetic Example 25 of Table 1, 550cc of ethanol, 36g of acetylacetone, Were mixed and placed in a high-pressure reactor having an internal volume of 1200 cc and reacted at 250 ° C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. Carbon quantum dots were formed in the composite. The black liquid composition was filtered through a membrane filter having a pore size of 0.1 占 퐉 to separate the black permeate. The permeate showed the characteristics of carbon quantum dots.

The UV-Vis absorption spectrum of the solution diluted with 1/20 of the permeation solution is shown in FIG. 25 (a) and the absorption coefficient at 0.25 nm is 0.263. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 5.25. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 25 (b) and (c), respectively, and the fluorescence color coordinates are (0.1772, 0.1111) and (0.1955, 0.2759), respectively. 25 (d) is a photograph of a test tube containing the synthesized solution. 25 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/20 ratio solution, and FIG. 25 (F) of Fig. The FT-IR spectrum of the permeate is shown in Fig. 25 (g). IR spectra show absorption peaks due to O-H, C-H, C = O, C-O and C-O-C bonds. The X-ray diffraction pattern measured by drying the permeated liquid is shown in Fig. 25 (h).

25 (i), (j) and (k) are photographs and results of TEM measurement of the permeated liquid. TEM image The size of spherical CQD can be confirmed in (i-1) of FIG. 25 (i-2) is an enlarged photograph of the portion (i-1) in Fig. 25, and is a CQD in which the crystal lattice plane is clearly visible. The diffraction pattern obtained by Fourier-transforming the crystal lattice of one particle in Fig. 25 (i-2) is (i-3) in Fig. Thereby forming a distorted hexagonal shape of the diffraction pattern. 25 (j-1) and (j-2) are carbon quantum dots whose crystal lattice planes are clearly measured, and the measured lattice distances and surface indices are shown. 25 (j-2) is a diffraction pattern obtained by Fourier transforming the crystal lattice. 25 (k) shows the size distribution of the carbon quantum dot particles measured by TEM, and the average size is about 4.40 nm.

26 shows the results of summarizing the characteristics of Synthesis Example 26 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 26 of Table 1, 45 cc of ethanol, 3 g of acetylacetone and 0.45 g of nitric acid were mixed and put in a high- And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at 1/15 ratio is shown in FIG. 26 (a), and the absorption coefficient at 500 nm is 0.148. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 2.23. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 26 (b) and 26 (c), respectively, and the fluorescence color coordinates are (0.1747, 0.1694) and (0.1887, 0.2590), respectively. Figure 26 (d) is a photograph of a test tube containing the synthesized solution. FIG. 26 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/15 ratio solution, and FIG. 26 (F) of Fig. 26.

27 shows the results of summarizing the characteristics of Synthesis Example 27 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 27 of Table 1, 45 cc of ethanol, 3 g of acetylacetone and 0.45 g of nitric acid were mixed and put into a high- And reacted at 230 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/5 ratio of the synthesis solution is shown in Fig. 27 (a), and the absorption coefficient at 0.25 nm is 0.233. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.16. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 27 (b) and (c), respectively, and the fluorescence color coordinates are (0.1711, 0.1608) and (0.1857, 0.2573), respectively. 27 is a photograph of a test tube containing the synthesized solution. (E) of FIG. 27 (b) is a photograph of the fluorescence emitted by irradiating with ultraviolet LED (380 nm) at the bottom of the glass bottle containing the diluted solution at 1/5 ratio, (F) of FIG.

28 shows the results of summarizing the properties of Synthesis Example 28 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 28 of Table 2, 45 cc of ethanol, 3 g of acetylacetone and 0.45 g of nitric acid were mixed and placed in a high- And reacted at 280 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/15 ratio of the synthesis solution is as shown in FIG. 28 (a), and the absorption coefficient at 500 nm is 0.0875. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.31. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 28 (b) and (c), respectively, and the fluorescence color coordinates are (0.1809, 0.1794) and (0.2035, 0.3331), respectively. 28 (d) is a photograph of a test tube containing the synthesized solution. FIG. 28 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/15 ratio solution, and FIG. 28 28 (f).

29 shows the results of summarizing the properties of Synthesis Example 29 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 29 of Table 2, 37.5 cc of ethanol, 3 g of acetylacetone and 1 g of nitric acid were mixed and placed in a high- And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at 1/36 ratio is as shown in FIG. 29 (a), and the absorption coefficient at 0.1 nm is 500 nm. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 6.24. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 29 (b) and (c), respectively, and the fluorescence color coordinates are (0.1808, 0.1770) and (0.1978, 0.2777), respectively. 29 (d) is a photograph of a test tube containing the synthesized solution. FIG. 29 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a 1/36 diluted solution, and FIG. 29 (F) of Fig. 29.

30 shows the results of summarizing the characteristics of Synthesis Example 30 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 30 of Table 2, 20 cc of ethanol, 9 g of acetylacetone and 3 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/500 ratio is as shown in Fig. 30 (a), and the absorption coefficient at 500 nm is 0.117. Based on the diluted ratio, the absorption coefficient of the permeate is 58.6. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 30 (b) and 30 (c), respectively, and the fluorescence color coordinates are (0.1973, 0.2186) and (0.2219, 0.3130), respectively. 30 (d) is a photograph of a test tube containing the synthesized solution. FIG. 30 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted at 1/500 ratio, and FIG. 30 (F) of Fig.

31 shows the results of summarizing the characteristics of Synthesis Example 31 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 31 of Table 1, 20 cc of ethanol, 15 g of acetylacetone and 5 g of nitric acid were mixed, Lt; 0 &gt; C for 20 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution diluted with a 1/200 ratio of the permeate is as shown in Fig. 31 (a), and the absorption coefficient at 500 nm is 0.376. Based on the diluted ratio, the absorption coefficient of the permeate is 75.1. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 31 (b) and (c), respectively, and the fluorescence color coordinates are (0.1870, 0.1943) and (0.2086, 0.2942), respectively. 31 (d) is a photograph of a test tube containing the synthesized solution. FIG. 31 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution diluted with a 1/200 ratio, and FIG. 31 (F) of Fig.

32 shows the results of summarizing the characteristics of Synthesis Example 32 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 32 of Table 2, 45 cc of ethanol, 3 g of citric acid and 0.45 g of nitric acid were mixed, Lt; 0 &gt; C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in Figure 32 (a) and the absorption coefficient at 0.3 nm is 500 nm. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 32 (b) and 32 (c), respectively, and the fluorescence color coordinates are (0.1809, 0.1811) and (0.1949, 0.2645), respectively. Figure 32 (d) is a photograph of a test tube containing the synthesized solution. (E) of FIG. 32 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the solution, and FIG. to be.

FIG. 33 shows the results of summarizing the characteristics of Synthesis Example 33 of carbon quantum dots synthesized by the method of the present invention. In Synthesis Example 33 of Table 2, 40 cc of ethanol, 3 g of vitamin C and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at a ratio of 1/100 is as shown in FIG. 33 (a), and the absorption coefficient at 500 nm is 0.256. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 25.6. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 33 (b) and 33 (c), respectively, and the fluorescence color coordinates are (0.1931, 0.2127) and (0.2143, 0.3034), respectively. 33 (d) is a photograph of a test tube containing the synthesized solution. FIG. 33 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted solution at 1/100 ratio, and FIG. 33 (F) of Fig.

34 shows the results of summarizing the properties of Synthesis Example 34 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 34 shown in Table 2, 20 cc of ethanol, 9 g of vitamin C and 3.24 g of nitric acid were mixed and placed in a high- And reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/100 ratio is as shown in Fig. 34 (a), and the absorption coefficient at 500 nm is 0.363. Based on the diluted ratio, the absorption coefficient of the permeate solution is 36.3. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 34 (b) and 34 (c), respectively, and the fluorescence color coordinates are (0.1795, 0.1834) and (0.1997, 0.2888), respectively. Figure 34 (d) is a photograph of a test tube containing the synthesized solution. FIG. 34 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle having a solution diluted with 1/100 ratio, and FIG. 34 34 (f).

35 shows the results of summarizing the characteristics of Synthesis Example 35 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 35 of Table 2, 37.5 cc of ethanol, 3 g of glutamine and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/31 ratio is as shown in Fig. 35 (a), and the absorption coefficient at 0.25 nm is 0.210. Based on the diluted ratio, the absorption coefficient of the permeate solution is 6.51. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 35 (b) and 35 (c), respectively, and the fluorescence color coordinates are (0.1816, 0.1790) and (0.1994, 0.2777), respectively. Figure 35 (d) is a photograph of a test tube containing the synthesized solution. FIG. 35 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a 1/31 ratio diluted solution, and FIG. 35 (F) of Fig.

36 shows the results of summarizing the properties of Synthesis Example 36 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 36 of Table 2, 37.5 cc of ethanol, 1 g of glucose and 3 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/81 ratio of the synthesis solution is shown in FIG. 36 (a), and the absorption coefficient at 0.3 nm is 0.320 at 500 nm. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 25.9. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 36 (b) and 36 (c), respectively, and the fluorescence color coordinates are (0.1931, 0.2300) and (0.2079, 0.3019), respectively. Figure 36 (d) is a photograph of a test tube containing the synthesized solution. FIG. 36 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/81 ratio solution, and FIG. 36 (F) of Fig.

37 shows the results of summarizing the properties of Synthesis Example 37 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 36 of Table 2, 37.5 cc of ethanol, 1 g of white sugar and 3 g of nitric acid were mixed and placed in a high- And reacted at 250 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of a solution obtained by diluting the permeation solution at 1/81 ratio is shown in FIG. 37 (a), and the absorption coefficient at 500 nm is 0.339. Based on the diluted ratio, the absorption coefficient of the permeate solution is 27.5. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 37 (b) and (c), respectively, and the fluorescence color coordinates are (0.1958, 0.2317) and (0.2206, 0.3368), respectively. Figure 37 (d) is a photograph of a test tube containing the synthesized solution. FIG. 37 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted at 1/81 ratio, and FIG. 37 37 (f).

38 shows the results of summarizing the characteristics of Synthesis Example 38 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 38 of Table 2, 20 cc of ethanol, 15 g of white sugar and 5 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/81 ratio of the synthesis solution is shown in FIG. 38 (a), and the absorption coefficient at 0.25 nm is 0.248. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 20.1. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 38 (b) and (c), respectively, and the fluorescence color coordinates are (0.1916, 0.2133) and (0.2232, 0.3121), respectively. Figure 38 (d) is a photograph of a test tube containing the synthesized solution. 38 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted 1/81 in proportion to the fluorescence emitted by a blue LED (460 nm) (F) of Fig.

39 shows the results of summarizing the properties of Synthesis Example 39 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 39 of Table 2, 37.5 cc of ethanol, 3 g of white sugar and 1 g of nitric acid were mixed and placed in a high- And reacted at 245 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/111 ratio of the synthesis solution is shown in Figure 39 (a), and the absorption coefficient at 500 nm is 0.201. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 22.4. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 39 (b) and 39 (c), respectively, and the fluorescence color coordinates are (0.2146, 0.2467) and (0.2505, 0.3324), respectively. 39 (d) is a photograph of a test tube containing the synthesized solution. FIG. 39 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution diluted with 1/111 ratio, and FIG. 39 (F) of Fig.

40 shows the results of summarizing the characteristics of Synthesis Example 40 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 40 of Table 2, 37.5 cc of ethanol, 3 g of tartaric acid and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/11 ratio is as shown in Fig. 40 (a), and the absorption coefficient at 500 nm is 0.391. Based on the diluted ratio, the absorption coefficient of the permeate is 4.30. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 40 (b) and 40 (c), respectively, and the fluorescence color coordinates are (0.1945, 0.2139) and (0.2187, 0.2951), respectively. 40 (d) is a photograph of a test tube containing the synthesized solution. FIG. 40 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted at 1/11 ratio, and FIG. 40 (F) of FIG.

41 shows the results of summarizing the characteristics of Synthesis Example 41 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 41 of Table 2, 45cc of ethanol, 3g of urea and 3g of nitric acid were mixed and put into a high- For 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/13 ratio of the synthesis solution is shown in FIG. 41 (a), and the absorption coefficient at 500 nm is 0.128. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.66. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 41 (b) and 41 (c), respectively, and the fluorescence color coordinates are (0.1749, 0.1496) and (0.0.2060, 0.2565), respectively. 41 (d) is a photograph of a test tube containing the synthesized solution. FIG. 41 (e) is a photograph showing fluorescence emitted by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/13 ratio solution, and FIG. 41 (F) of Fig.

42 shows the results of summarizing the characteristics of Synthesis Example 42 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 42 of Table 2, 37.5 cc of ethanol, 3 g of acetone and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at a ratio of 1/10 is shown in FIG. 42 (a), and the absorption coefficient at 500 nm is 0.156. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.56. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 42 (b) and 42 (c), respectively, and the fluorescence color coordinates are (0.1692, 0.1439) and (0.0.1884, 0.2437), respectively. Figure 42 (d) is a photograph of a test tube containing the synthesized solution. FIG. 42 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/10 ratio solution, and FIG. 42 42 (f).

43 shows the results of summarizing the characteristics of Synthesis Example 43 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 43 of Table 2, 37.5 cc of ethanol, 3 g of ethylene glycol and 1 g of nitric acid were mixed and placed in a high- And reacted at 245 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate solution at 1/15 ratio is shown in FIG. 43 (a), and the absorption coefficient at 0.25 nm is 0.252. Based on the diluted ratio, the absorption coefficient of the permeate solution is 3.78. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 43 (b) and 43 (c), respectively, and the fluorescence color coordinates are (0.1951, 0.2402) and (0.2221, 0.3180), respectively. Figure 43 (d) is a photograph of a test tube containing the synthesized solution. FIG. 43 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/15 ratio solution, and FIG. 43 (F) of Fig.

44 shows the results of summarizing the characteristics of Synthesis Example 44 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 44 of Table 2, 37.5 cc of ethanol, 3 g of starch and 1 g of nitric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution diluted with the 1/56 ratio of the permeation solution is shown in FIG. 44 (a), and the absorption coefficient at 0.6 nm is 0.699. Based on the diluted ratio, the absorption coefficient of the permeate solution is 39.1. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 44 (b) and 44 (c), respectively, and the fluorescence color coordinates are (0.2084, 0.2464) and (0.2402, 0.3322), respectively. Figure 44 (d) is a photograph of a test tube containing the synthesized solution. Figure 44 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a solution diluted at 1/56 ratio, (F) of Fig.

45 shows the results of summarizing the characteristics of Synthesis Example 45 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 45 of Table 2, 45 cc of ethanol, 3 g of oleic acid and 0.16 g of nitric acid were mixed and put in a high- And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 45 (a), and the absorption coefficient at 500 nm is 0.650. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 45 (b) and 45 (c), respectively, and the fluorescence color coordinates are (0.1801, 0.1885) and (0.1951, 2838), respectively. Figure 45 (d) is a photograph of a test tube containing the synthesized solution. Figure 45 (e) shows the fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of the glass bottle containing the solution, and Figure 45 (f) to be.

46 shows the results of summarizing the characteristics of Synthesis Example 46 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 46 of Table 2, 40 cc of 2-propanol, 3 g of acetylacetone and 3 g of nitric acid were mixed, And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted 1/20 of the synthesis solution is shown in Figure 46 (a), and the absorption coefficient at 500 nm is 0.214. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 4.27. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 46 (b) and 46 (c), respectively, and the fluorescence color coordinates are (0.1778, 0.1724) and (0.1956, 0.2712), respectively. Figure 46 (d) is a photograph of a test tube containing the synthesized solution. FIG. 46 (e) shows a fluorescence image taken by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/20 ratio solution, and FIG. 46 46 (f).

47 shows the results of summarizing the properties of Synthesis Example 47 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 47 of Table 2, 37.5 cc of n-propanol, 3 g of acetylacetone and 1 g of nitric acid were mixed, And reacted at 250 &lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution obtained by diluting the synthesis solution at 1/36 ratio is shown in FIG. 47 (a), and the absorption coefficient at 0.1 nm is 500 nm. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 5.28. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 47 (b) and 47 (c), respectively, and the fluorescence color coordinates are (0.1796, 0.1714) and (0.2039, 0.2648), respectively. 47 is a photograph of a test tube containing the synthesized solution. FIG. 47 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a 1/36 diluted solution, and FIG. 47 47 (f).

48 shows the results of summarizing the properties of Synthesis Example 48 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 48 of Table 2, 37.5 cc of chlorobenzene, 3 g of acetylacetone and 1 g of nitric acid were mixed, And reacted at 245 DEG C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeation solution at 1/46 ratio is shown in FIG. 48 (a), and the absorption coefficient at 500 nm is 0.446. Based on the diluted ratio, the absorption coefficient of the permeate solution is 20.5. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 48 (b) and 48 (c), respectively, and the fluorescence color coordinates are (0.1893, 0.2005) and (0.2165, 0.2884), respectively. 48 (d) is a photograph of a test tube containing the synthesized solution. Figure 48 (e) shows a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution diluted 1/46, 48 (f).

49 shows the results of summarizing the characteristics of Synthesis Example 49 of carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 49 of Table 2, 37.5 cc of ethanol, 3 g of glucose and 1 g of sulfuric acid were mixed, Lt; 0 &gt; C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/36 ratio is shown in FIG. 49 (a), and the absorption coefficient at 500 nm is 0.039. Based on the diluted ratio, the absorption coefficient of the permeate is 1.42. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 49 (b) and 49 (c), respectively, and the fluorescence color coordinates are (0.1795, 0.1848) and (0.2148, 0.2917), respectively. Figure 49 (d) is a photograph of a test tube containing the synthesized solution. FIG. 49 (e) shows a fluorescence image taken by irradiating ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/36 ratio solution, and FIG. 49 49 (f).

50 shows the results of summarizing the characteristics of Synthesis Example 50 of carbon quantum dots synthesized by the method of the present invention. In Synthesis Example 50 of Table 2, ₄₀ cc of ethanol, 1 g of white sugar, 1 g of potassium borohydride (KBH ₄ ) Were added to the autoclave and reacted at 245 ° C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled. The mixture was filtered through a membrane filter with a pore size of 0.2 mu m to separate the black permeate.

The UV-Vis absorption spectrum of the solution obtained by diluting the permeate at 1/36 ratio is shown in FIG. 50 (a), and the absorption coefficient at 500 nm is 0.294. Based on the diluted ratio, the absorption coefficient of the permeate is 10.6. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 50 (b) and 50 (c), respectively, and the fluorescence color coordinates are (0.2051, 0.2260) and (0.2416, 0.3150), respectively. 50 (d) is a photograph of a test tube containing the synthesized solution. FIG. 50 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/36 ratio solution, and FIG. 50 50 (f).

51 shows the results of summarizing the characteristics of the synthesis example 51 of the carbon quantum dots synthesized by the method of the present invention. In the case of the synthesis example 51 of Table 2, 40 cc of ethanol, 3 g of acetylacetone, 1 g of potassium borohydride (KBH ₄ ) Were added to the autoclave and reacted at 245 ° C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/13 ratio of the synthesis solution is shown in FIG. 51 (a), and the absorption coefficient at 500 nm is 0.303. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 3.94. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 51 (b) and 51 (c), respectively, and the fluorescence color coordinates are (0.2286, 0.2540) and (0.2667, 0.3235), respectively. 51 (d) is a photograph of a test tube containing the synthesized solution. 51 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing a diluted 1/13 ratio solution, and FIG. 51 51 (f).

52 shows the results of summarizing the characteristics of the synthesis example 52 of the carbon quantum dot synthesized by the method of the present invention. In the synthesis example 52 of Table 2, 37.5 cc of ethanol, 3 g of benzene, 0.69 g of potassium borohydride (KBH ₄ ) g were added to the autoclave and reacted at 245 ° C for 30 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the solution diluted with the 1/11 ratio of the synthesis solution is shown in Figure 52 (a), and the absorption coefficient at 500 nm is 0.142. Based on the diluted ratio, the absorption coefficient of the synthesis solution is 1.56. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIG. 52 (c) and the fluorescence color coordinates are (0.1853, 0.1906) and (0.2199, 0.2992), respectively. Figure 52 (d) is a photograph of a test tube containing the synthesized solution. FIG. 52 (e) shows a fluorescence image taken by irradiating with ultraviolet LED (380 nm) at the bottom of a glass bottle containing a diluted 1/11 ratio solution, and FIG. 52 (F) of Fig.

53 shows the results of summarizing the properties of Synthesis Example 53 of the carbon quantum dots synthesized by the method of the present invention. In the case of Synthesis Example 53 of Table 2, 45 cc of ethanol, 3 g of acetylacetone and 0.3 g of Fe ₂ O ₃ nanoparticles And the reaction was carried out at 250 ° C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in Figure 53 (a), and the absorption coefficient at 500 nm is 0.047. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 53 (b) and (c), respectively, and the fluorescence color coordinates are (0.1781, 0.1751) and (0.2045, 0.2750), respectively. Figure 53 (d) is a photograph of a test tube containing the synthesized solution. 53 (e) is a photograph of fluorescence emitted by irradiating with ultraviolet LED (380 nm) from the bottom of a glass bottle containing a solution, and FIG. 53 (f) to be.

54 shows the results of summarizing the characteristics of Synthesis Example 54 of the carbon quantum dot synthesized by the method of the present invention. In the case of Synthesis Example 54 of Table 2, 42.5 cc of ethanol, 3 g of acetylacetone and 0.5 cc of acetic acid were mixed, And reacted at 250 DEG C for 35 hours. During the reaction, the solution was magneticly stirred at 200 rpm for the first 9 hours to keep the solution homogeneous. After the reaction, the autoclave was naturally cooled.

The UV-Vis absorption spectrum of the synthesis solution is shown in FIG. 54 (a), and the absorption coefficient at 500 nm is 0.0173. The fluorescence spectra measured by excitation with light of 365 nm and 400 nm are shown in FIGS. 54 (b) and (c), respectively, and the fluorescence color coordinates are (0.1745, 0.1637) and (0.1988, 0.2505), respectively. Figure 54 (d) is a photograph of a test tube containing the synthesized solution. 54 (e) is a photograph of fluorescence emitted by irradiating ultraviolet LED (380 nm) from the bottom of a glass bottle containing the solution, and FIG. 54 (f) to be.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

Claims (9)

Organic compound,
A solvent which is at least one of methanol, ethanol, 2-propanol, n-propanol, hydrogen peroxide and chlorobenzene,
Mixing a promoter to form a solution; And
Heating the solution using a high-pressure reactor at a temperature of at least &lt; RTI ID = 0.0 &gt; 220 C. &lt; / RTI &gt; The method according to claim 1,
Wherein the promoter is at least one of an oxidizing agent, a reducing agent, and a catalyst. 3. The method of claim 2,
Wherein the oxidizing agent is at least one of nitric acid, sulfuric acid, and hydrogen peroxide. 3. The method of claim 2,
Wherein the reducing agent is potassium borohydride. 3. The method of claim 2,
The catalyst is Fe ₂ O ₃ Wherein the carbon nanoparticles are nanoparticles. delete The method according to claim 1,
Wherein the organic compound is at least one of sugar, starch, vitamin C, glucose, tartaric acid, citric acid, oleic acid, glutamine, glutamic acid, urea, benzene, acetylacetone, acetophenone and acetic acid. delete delete

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