Preparation method of high-activity carbon quantum dots, high-activity carbon quantum dots and application

Abstract

The invention provides a preparation method of a high-activity carbon quantum dot, the high-activity carbon quantum dot and application, and relates to the technical field of carbon quantum dots, the preparation method comprises the following steps: S1, dissolving glucose, polyethylene glycol and Eu < 3 + > ions in deionized water to form a mixed solution; s2, under the stirring condition, adding a sodium hydroxide solution into the mixed solution, and adjusting the pH value to obtain a mixed solution; s3, starting the microwave reaction device, and setting power and time; a surface modifier polyethylene glycol is introduced to accurately control the surface chemical properties of the carbon quantum dots, the dispersibility and stability of the carbon quantum dots are improved, a fluorescence enhancer Eu < 3 + > ions are introduced to improve the fluorescence quantum yield and fluorescence stability of the carbon quantum dots, glucose is synchronously used as a carbon source, a sodium hydroxide solution is added to adjust the PH, and the fluorescence intensity of the carbon quantum dots is improved. The preparation method is optimized and synthesized with the regulator, so that the yield and the reaction efficiency are improved, and accurate regulation and control on the particle size and the morphology of the carbon quantum dots are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon quantum dots, and in particular to a preparation method of highly active carbon quantum dots, highly active carbon quantum dots and applications. Background Art

[0002] Carbon quantum dots, also known as carbon dots or carbon nanodots, are a class of zero-dimensional nanomaterials with significant fluorescent properties. These nanoparticles are composed of ultrafine, dispersed, quasi-spherical carbon nanoparticles with a size below 10nm. Carbon quantum dots have many advantages such as excellent optical properties, good water solubility, low toxicity, environmental friendliness, wide source of raw materials, low cost, good biocompatibility, etc. In addition, they also have high chemical stability and can maintain their optical properties and stability under different environmental conditions. These characteristics of carbon quantum dots make them widely used in many fields, such as imaging and drug delivery in the biomedical field, as well as energy storage and optoelectronic devices, such as solar cells and photoelectrocatalysis.

[0003] Traditional methods for preparing carbon quantum dots often have problems such as uneven particle size distribution, low interfacial activity, complex preparation process or high cost. For example, although the reverse microemulsion method can obtain carbon quantum dots with high fluorescence yield, the steps are cumbersome; although the electrochemical method is simple, the selection of raw materials is limited in some cases; the arc discharge method has problems such as difficult purification and low fluorescence efficiency. In general, the carbon quantum dots prepared by the above preparation methods are not active enough. In the prior art, for example, the authorization announcement No. CN114956052B discloses "a preparation method of high-activity carbon quantum dots, high-activity carbon quantum dots and applications", and specifically discloses: using aldehydes and bases as core raw materials, forming carbon quantum dots by cross-linking polymerization, using capping agents to regulate the particle size of high-activity carbon quantum dots, and using activators to enhance the interfacial activity of carbon quantum dots; however, in the above-mentioned technology, the optimization synthesis method is mainly adopted, the technology is single, and the activity improvement is limited. Therefore, the present invention proposes a preparation method of high-activity carbon quantum dots, high-activity carbon quantum dots and applications to solve the problems existing in the prior art. Summary of the invention

[0004] In response to the above problems, the present invention proposes a preparation method of highly active carbon quantum dots, highly active carbon quantum dots and applications. The preparation method of highly active carbon quantum dots adopts a three-in-one approach of changing surface chemical properties, optimizing synthesis methods and enhancing fluorescence properties, so that the carbon quantum dots have higher activity.

[0005] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for preparing highly active carbon quantum dots, comprising the following steps:

[0006] S1: dissolving glucose, polyethylene glycol and Eu3+ ions in deionized water to form a mixed solution;

[0007] S2: adding sodium hydroxide solution to the mixed solution under stirring conditions to adjust the pH value to obtain a mixed solution;

[0008] S3: Start the microwave reaction device, set the power and time, so that the mixed solution undergoes a carbonization reaction under the action of microwaves to generate carbon quantum dot products;

[0009] S4: After the reaction is completed, the product is cooled to room temperature, and impurities are removed through centrifugation and washing steps to obtain pure carbon quantum dots.

[0010] S5: Characterize and analyze the purified carbon quantum dots to confirm their morphology, particle size distribution and fluorescence properties.

[0011] A further improvement is that in S1, the raw materials are prepared according to the following mass ratio: 50-60 parts of glucose, 5-10 parts of polyethylene glycol, 0.01-0.03 parts of Eu3+ ions, 500-600 parts of deionized water and 10-20 parts of sodium hydroxide.

[0012] A further improvement is that: S2 comprises the following steps:

[0013] S21: pouring the mixed solution into a stirring container and stirring at 200 r / min for 3-5 min;

[0014] S22: pouring the sodium hydroxide solution into the stirring container, controlling the stirring speed to 1000 r / min, and stirring for 15-30 min;

[0015] S23: Adjust the pH value to 8-10, and simultaneously use ultrasonic means to homogenize the inside of the stirring container.

[0016] A further improvement is that in S23, the frequency of ultrasonic treatment is controlled to be 35-45kHz and the power is controlled to be 100W.

[0017] A further improvement is that: S3 comprises the following steps:

[0018] S31: putting the mixed solution homogenized in S2 into a microwave reaction device, setting the microwave power to 500-1000W, and controlling the reaction time to 20-40min;

[0019] S32: During the reaction, glucose decomposes and carbonizes to form carbon quantum dots, while polyethylene glycol and Eu3+ ions modify the surface of carbon quantum dots and enhance their fluorescence, respectively;

[0020] S33: After the reaction time is over, the microwave reaction device is left to stand.

[0021] A further improvement is that: said S4 comprises the following steps:

[0022] S41: Cool the product to room temperature, transfer it to a centrifuge tube, put it into a centrifuge after balancing, and centrifuge it at 2000 r / min;

[0023] S42: During centrifugation, the product settles at the bottom of the centrifuge tube, while impurities and unreacted products remain in the supernatant;

[0024] S43: selecting deionized water, ethanol, or acetone as a washing liquid, and washing the centrifuged product with the washing liquid. During washing, shaking the centrifuge tube to allow the washing liquid to fully contact the product;

[0025] S44: performing centrifugation again to remove the washing solution and residual impurities, and repeating the process 2-4 times until the washing solution becomes clear;

[0026] S45: The washed product is taken out from the centrifuge tube, and then dried to obtain pure carbon quantum dots.

[0027] A further improvement is that in S45, the drying process is carried out by combining vacuum drying and freeze drying.

[0028] A further improvement is that: S5 comprises the following steps:

[0029] S51: Use high-energy electron beams to penetrate the sample, and use the scattered electrons generated by the collision between the electrons and the atoms in the sample to form an image, and use a transmission electron microscope to observe its shape, size and dispersion;

[0030] S52: Using a nanoparticle size analyzer, the particle size distribution is inferred by measuring the fluctuation of the intensity of scattered light from particles in the sample;

[0031] S53: Using a fluorescence spectrometer: measure the fluorescence intensity of the sample under different wavelengths of excitation light to determine the optimal excitation wavelength;

[0032] S54: Measure fluorescence decay time using time-correlated single photon counting (TCSPC) technique.

[0033] A highly active carbon quantum dot is prepared by using the above-mentioned method for preparing the highly active carbon quantum dot.

[0034] An application of highly active carbon quantum dots, including the application of the highly active carbon quantum dots in the fields of aerospace, aviation, automobile, electronics, machinery and chemical industry.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention introduces a surface modifier, polyethylene glycol, to precisely control the surface chemical properties of carbon quantum dots, thereby improving their dispersibility and stability. It introduces a fluorescence enhancer, Eu3+ ions, to improve the fluorescence quantum yield and fluorescence stability of the carbon quantum dots. Glucose is simultaneously used as a carbon source, sodium hydroxide solution is added to adjust the pH, and the above-mentioned regulators are used for optimized synthesis, thereby improving the yield and reaction efficiency, and achieving precise control of the particle size and morphology of the carbon quantum dots. In summary, a trinity approach of changing the surface chemical properties, optimizing the synthesis method, and enhancing the fluorescence performance is adopted to make the carbon quantum dots more active.

[0037] 2. When adjusting the pH value, the present invention uses ultrasonic means to homogenize the inside of the stirring container to improve the uniformity of the mixing. During the microwave treatment, the power is controlled to be 500-1000W and the reaction time is 20-40min. It has been verified that the stability of the reaction is effectively guaranteed to avoid the situation where the reaction violently damages the device and raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0039] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0040] Embodiment 1

[0041] according to Figure 1 As shown, this embodiment proposes a method for preparing highly active carbon quantum dots, comprising the following steps:

[0042] Prepare raw materials according to the following mass ratio: 50 parts of glucose, 5 parts of polyethylene glycol, 0.01 parts of Eu3+ ions, 500 parts of deionized water and 10 parts of sodium hydroxide, and dissolve glucose, polyethylene glycol and Eu3+ ions in deionized water to form a mixed solution;

[0043] Glucose: as the main carbon source; polyethylene glycol: as a surface modifier, forming an effective coating layer on the surface of carbon quantum dots; Eu3+ ions: as fluorescence enhancers, significantly affecting the fluorescence properties of carbon quantum dots; deionized water: as a solvent; sodium hydroxide: used to adjust the pH value of the reaction system, and the amount will be adjusted according to the pH test to ensure that the reaction is carried out under appropriate pH conditions.

[0044] Under stirring conditions, sodium hydroxide solution is added to the mixed solution, and the pH value is adjusted to obtain a mixed solution; the method specifically comprises the following steps: pouring the mixed solution into a stirring container, stirring at 200 r / min for 3-5 minutes; pouring the sodium hydroxide solution into the stirring container, controlling the stirring speed to 1000 r / min, and stirring for 15-30 minutes; adjusting the pH value to 8-10, and simultaneously homogenizing the inside of the stirring container by means of ultrasound; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W; when adjusting the pH value, the method homogenizes the inside of the stirring container by means of ultrasound to improve the uniformity of the mixing.

[0045] The microwave reaction device is started, and the power and time are set so that the mixed solution undergoes a carbonization reaction under the action of microwaves to generate a carbon quantum dot product; the steps specifically include: the mixed solution after S2 homogenization is put into the microwave reaction device, the microwave power is set to 500-1000W, and the reaction time is controlled to 20-40min; during the reaction, glucose is decomposed and carbonized to form carbon quantum dots, and polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance the fluorescence; after the reaction time is over, the microwave reaction device is left standing;

[0046] The setting of microwave power has an important influence on the reaction rate and the properties of the product. Higher power can accelerate the reaction, but it may also cause the reaction to be too violent, produce undesirable byproducts or destroy the structure of the product. Therefore, the microwave power is set to 500-1000W. The reaction time is also an important factor affecting the properties of the product. Too short a reaction time may lead to incomplete reaction and low product yield; while too long a reaction time may lead to excessive carbonization of the product, affecting its fluorescence performance or other properties. Therefore, the reaction time is controlled to 20-40min.

[0047] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, an ice bath or other cooling equipment can be used to externally cool the reaction vessel. The cooling rate should not be too fast to avoid damage to the product caused by thermal stress caused by a sudden drop in temperature;

[0048] Then, impurities are removed by centrifugation and washing steps to obtain pure carbon quantum dots, which specifically includes the following steps: cooling the product to room temperature, transferring it to a centrifuge tube, placing it in a centrifuge after balancing, and centrifuging it at 2000r / min; during the centrifugation process, the product is deposited at the bottom of the centrifuge tube, while impurities and unreacted substances remain in the upper clear liquid; ionized water, ethanol, and acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to allow the washing liquid to fully contact with the product; centrifugation is performed again to remove the washing liquid and residual impurities, and the process is repeated 2-4 times until the washing liquid becomes clear; the washed product is taken out of the centrifuge tube, and then dried to obtain pure carbon quantum dots, and the drying process is performed by a combination of vacuum drying and freeze drying;

[0049] The purified carbon quantum dots are characterized and analyzed to confirm their morphology, particle size distribution and fluorescence properties. Specifically, the following steps are included: using a high-energy electron beam to penetrate the sample, imaging the scattered electrons generated by the collision of electrons with atoms in the sample, and observing its shape, size and dispersion using a transmission electron microscope; using a nanoparticle size analyzer to infer the particle size distribution of the particles by measuring the fluctuation of the intensity of scattered light from particles in the sample; using a fluorescence spectrometer: measuring the fluorescence intensity of the sample under different wavelengths of excitation light to determine the optimal excitation wavelength; using time-correlated single photon counting (TCSPC) technology to measure the fluorescence decay time. Other characterization methods: X-ray diffraction (XRD): used to analyze the crystal structure of carbon quantum dots. Raman spectroscopy: provides structural information of carbon materials, such as the degree of graphitization, defects, etc. Fourier transform infrared spectroscopy (FTIR): analyzes the functional groups and chemical bonds on the surface of carbon quantum dots. Ultraviolet-visible absorption spectroscopy (UV-Vis): assists in analyzing the optical properties of carbon quantum dots, such as absorption sidebands. Through the above characterization methods, the morphology, particle size distribution and fluorescence properties of the purified carbon quantum dots can be comprehensively evaluated, providing an important basis for their subsequent applications.

[0050] Embodiment 2

[0051] according to Figure 1 As shown, this embodiment proposes a method for preparing highly active carbon quantum dots, comprising the following steps:

[0052] Prepare raw materials according to the following mass ratio: 55 parts of glucose, 8 parts of polyethylene glycol, 0.02 parts of Eu3+ ions, 550 parts of deionized water and 15 parts of sodium hydroxide, and dissolve glucose, polyethylene glycol and Eu3+ ions in deionized water to form a mixed solution;

[0053] Glucose: as the main carbon source; polyethylene glycol: as a surface modifier, forming an effective coating layer on the surface of carbon quantum dots; Eu3+ ions: as fluorescence enhancers, significantly affecting the fluorescence properties of carbon quantum dots; deionized water: as a solvent; sodium hydroxide: used to adjust the pH value of the reaction system, and the amount will be adjusted according to the pH test to ensure that the reaction is carried out under appropriate pH conditions.

[0054] Under stirring conditions, sodium hydroxide solution is added to the mixed solution, and the pH value is adjusted to obtain a mixed solution; the method specifically comprises the following steps: pouring the mixed solution into a stirring container, stirring at 200 r / min for 3-5 minutes; pouring the sodium hydroxide solution into the stirring container, controlling the stirring speed to 1000 r / min, and stirring for 15-30 minutes; adjusting the pH value to 8-10, and simultaneously homogenizing the inside of the stirring container by means of ultrasound; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W; when adjusting the pH value, the method homogenizes the inside of the stirring container by means of ultrasound to improve the uniformity of the mixing.

[0055] The microwave reaction device is started, and the power and time are set so that the mixed solution undergoes a carbonization reaction under the action of microwaves to generate a carbon quantum dot product; the steps specifically include: the mixed solution after S2 homogenization is put into the microwave reaction device, the microwave power is set to 500-1000W, and the reaction time is controlled to 20-40min; during the reaction, glucose is decomposed and carbonized to form carbon quantum dots, and polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance the fluorescence; after the reaction time is over, the microwave reaction device is left standing;

[0056] The setting of microwave power has an important influence on the reaction rate and the properties of the product. Higher power can accelerate the reaction, but it may also cause the reaction to be too violent, produce undesirable byproducts or destroy the structure of the product. Therefore, the microwave power is set to 500-1000W. The reaction time is also an important factor affecting the properties of the product. Too short a reaction time may lead to incomplete reaction and low product yield; while too long a reaction time may lead to excessive carbonization of the product, affecting its fluorescence performance or other properties. Therefore, the reaction time is controlled to 20-40min.

[0057] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, an ice bath or other cooling equipment can be used to externally cool the reaction vessel. The cooling rate should not be too fast to avoid damage to the product caused by thermal stress caused by a sudden drop in temperature;

[0058] Then, impurities are removed by centrifugation and washing steps to obtain pure carbon quantum dots, which specifically includes the following steps: cooling the product to room temperature, transferring it to a centrifuge tube, placing it in a centrifuge after balancing, and centrifuging it at 2000r / min; during the centrifugation process, the product is deposited at the bottom of the centrifuge tube, while impurities and unreacted substances remain in the upper clear liquid; ionized water, ethanol, and acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to allow the washing liquid to fully contact with the product; centrifugation is performed again to remove the washing liquid and residual impurities, and the process is repeated 2-4 times until the washing liquid becomes clear; the washed product is taken out of the centrifuge tube, and then dried to obtain pure carbon quantum dots, and the drying process is performed by a combination of vacuum drying and freeze drying;

[0059] The purified carbon quantum dots are characterized and analyzed to confirm their morphology, particle size distribution and fluorescence properties. Specifically, the following steps are included: using a high-energy electron beam to penetrate the sample, imaging the scattered electrons generated by the collision of electrons with atoms in the sample, and observing its shape, size and dispersion using a transmission electron microscope; using a nanoparticle size analyzer to infer the particle size distribution of the particles by measuring the fluctuation of the intensity of scattered light from particles in the sample; using a fluorescence spectrometer: measuring the fluorescence intensity of the sample under different wavelengths of excitation light to determine the optimal excitation wavelength; using time-correlated single photon counting (TCSPC) technology to measure the fluorescence decay time. Other characterization methods: X-ray diffraction (XRD): used to analyze the crystal structure of carbon quantum dots. Raman spectroscopy: provides structural information of carbon materials, such as the degree of graphitization, defects, etc. Fourier transform infrared spectroscopy (FTIR): analyzes the functional groups and chemical bonds on the surface of carbon quantum dots. Ultraviolet-visible absorption spectroscopy (UV-Vis): assists in analyzing the optical properties of carbon quantum dots, such as absorption sidebands. Through the above characterization methods, the morphology, particle size distribution and fluorescence properties of the purified carbon quantum dots can be comprehensively evaluated, providing an important basis for their subsequent applications.

[0060] Embodiment 3

[0061] according to Figure 1 As shown, this embodiment proposes a method for preparing highly active carbon quantum dots, comprising the following steps:

[0062] Prepare raw materials according to the following mass ratio: 60 parts of glucose, 10 parts of polyethylene glycol, 0.03 parts of Eu3+ ions, 600 parts of deionized water and 20 parts of sodium hydroxide, and dissolve glucose, polyethylene glycol and Eu3+ ions in deionized water to form a mixed solution;

[0063] Glucose: as the main carbon source; polyethylene glycol: as a surface modifier, forming an effective coating layer on the surface of carbon quantum dots; Eu3+ ions: as fluorescence enhancers, significantly affecting the fluorescence properties of carbon quantum dots; deionized water: as a solvent; sodium hydroxide: used to adjust the pH value of the reaction system, and the amount will be adjusted according to the pH test to ensure that the reaction is carried out under appropriate pH conditions.

[0064] Under stirring conditions, sodium hydroxide solution is added to the mixed solution, and the pH value is adjusted to obtain a mixed solution; the method specifically comprises the following steps: pouring the mixed solution into a stirring container, stirring at 200 r / min for 3-5 minutes; pouring the sodium hydroxide solution into the stirring container, controlling the stirring speed to 1000 r / min, and stirring for 15-30 minutes; adjusting the pH value to 8-10, and simultaneously homogenizing the inside of the stirring container by means of ultrasound; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W; when adjusting the pH value, the method homogenizes the inside of the stirring container by means of ultrasound to improve the uniformity of the mixing.

[0065] The microwave reaction device is started, and the power and time are set so that the mixed solution undergoes a carbonization reaction under the action of microwaves to generate a carbon quantum dot product; the steps specifically include: the mixed solution after S2 homogenization is put into the microwave reaction device, the microwave power is set to 500-1000W, and the reaction time is controlled to 20-40min; during the reaction, glucose is decomposed and carbonized to form carbon quantum dots, and polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance the fluorescence; after the reaction time is over, the microwave reaction device is left standing;

[0066] The setting of microwave power has an important influence on the reaction rate and the properties of the product. Higher power can accelerate the reaction, but it may also cause the reaction to be too violent, produce undesirable byproducts or destroy the structure of the product. Therefore, the microwave power is set to 500-1000W. The reaction time is also an important factor affecting the properties of the product. Too short a reaction time may lead to incomplete reaction and low product yield; while too long a reaction time may lead to excessive carbonization of the product, affecting its fluorescence performance or other properties. Therefore, the reaction time is controlled to 20-40min.

[0067] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, an ice bath or other cooling equipment can be used to externally cool the reaction vessel. The cooling rate should not be too fast to avoid damage to the product caused by thermal stress caused by a sudden drop in temperature;

[0068] Then, impurities are removed by centrifugation and washing steps to obtain pure carbon quantum dots, which specifically includes the following steps: cooling the product to room temperature, transferring it to a centrifuge tube, placing it in a centrifuge after balancing, and centrifuging it at 2000r / min; during the centrifugation process, the product is deposited at the bottom of the centrifuge tube, while impurities and unreacted substances remain in the upper clear liquid; ionized water, ethanol, and acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to allow the washing liquid to fully contact with the product; centrifugation is performed again to remove the washing liquid and residual impurities, and the process is repeated 2-4 times until the washing liquid becomes clear; the washed product is taken out of the centrifuge tube, and then dried to obtain pure carbon quantum dots, and the drying process is performed by a combination of vacuum drying and freeze drying;

[0069] The purified carbon quantum dots are characterized and analyzed to confirm their morphology, particle size distribution and fluorescence properties. Specifically, the following steps are included: using a high-energy electron beam to penetrate the sample, imaging the scattered electrons generated by the collision of electrons with atoms in the sample, and observing its shape, size and dispersion using a transmission electron microscope; using a nanoparticle size analyzer to infer the particle size distribution of the particles by measuring the fluctuation of the intensity of scattered light from particles in the sample; using a fluorescence spectrometer: measuring the fluorescence intensity of the sample under different wavelengths of excitation light to determine the optimal excitation wavelength; using time-correlated single photon counting (TCSPC) technology to measure the fluorescence decay time. Other characterization methods: X-ray diffraction (XRD): used to analyze the crystal structure of carbon quantum dots. Raman spectroscopy: provides structural information of carbon materials, such as the degree of graphitization, defects, etc. Fourier transform infrared spectroscopy (FTIR): analyzes the functional groups and chemical bonds on the surface of carbon quantum dots. Ultraviolet-visible absorption spectroscopy (UV-Vis): assists in analyzing the optical properties of carbon quantum dots, such as absorption sidebands. Through the above characterization methods, the morphology, particle size distribution and fluorescence properties of the purified carbon quantum dots can be comprehensively evaluated, providing an important basis for their subsequent applications.

[0070] According to Example 1, Example 2 and Example 3, it can be concluded that the carbon quantum dots prepared by the present invention have higher activity by using the following mass ratio components: 50-60 parts of glucose, 5-10 parts of polyethylene glycol, 0.01-0.03 parts of Eu3+ ions, 500-600 parts of deionized water and 10-20 parts of sodium hydroxide.

[0071] Comparative Example:

[0072] 100g of 40wt.% acetaldehyde solution was selected, 3g of glucose was added as a capping agent, 6g of sodium p-aminosalicylate was added as an active agent, and the mixture was fully dissolved under stirring. Then 25g of sodium hydroxide was added as an alkaline substance, and the reaction temperature was controlled to react at 60°C for 4h while stirring. After the reaction was completed, the mixture was allowed to stand for 24h, and then filtered, washed, dialyzed and dried to obtain highly active carbon quantum dots with uniform particle size and high interfacial activity.

[0073] Verification example:

[0074] The highly active carbon quantum dots obtained in Examples 1-3, the carbon quantum dots obtained in the comparative example, and the carbon quantum dots obtained by the common method were respectively prepared into 0.05wt.% solutions, and the oil recovery test was performed. The recovery factor data obtained are shown in the following table:

[0075]

[0076] The present invention introduces a surface modifier polyethylene glycol, accurately controls the surface chemical properties of carbon quantum dots, improves its dispersibility and stability, introduces a fluorescence enhancer Eu3+ ion, improves the fluorescence quantum yield and fluorescence stability of carbon quantum dots, uses glucose as a carbon source, adds sodium hydroxide solution to adjust the pH, and optimizes the synthesis with the above-mentioned regulator to improve the yield and reaction efficiency, and achieves accurate regulation of the particle size and morphology of carbon quantum dots. In summary, the trinity of changing the surface chemical properties, optimizing the synthesis method and enhancing the fluorescence performance is adopted to make the activity of carbon quantum dots higher. And when the present invention adjusts the pH value, the inside of the stirring container is homogenized by ultrasonic means to improve the uniformity of its mixing. During the microwave treatment, the power is controlled to be 500-1000W and the reaction time is 20-40min. It has been verified that the stability of the reaction is effectively guaranteed to avoid the situation where the reaction violently destroys the device and raw materials.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing highly active carbon quantum dots, characterized in that: The following steps are involved: S1: dissolving glucose, polyethylene glycol and Eu3+ ions in deionized water to form a mixed solution; S2: adding sodium hydroxide solution to the mixed solution under stirring conditions to adjust the pH value to obtain a mixed solution; S3: Start the microwave reaction device, set the power and time, so that the mixed solution undergoes a carbonization reaction under the action of microwaves to generate carbon quantum dot products; S4: After the reaction is completed, the product is cooled to room temperature, and impurities are removed through centrifugation and washing steps to obtain pure carbon quantum dots. S5: Characterize and analyze the purified carbon quantum dots to confirm their morphology, particle size distribution and fluorescence properties.

2. The method for preparing highly active carbon quantum dots according to claim 1, characterized in that: In S1, raw materials are prepared according to the following mass ratio: 50-60 parts of glucose, 5-10 parts of polyethylene glycol, 0.01-0.03 parts of Eu3+ ions, 500-600 parts of deionized water and 10-20 parts of sodium hydroxide.

3. The method for preparing highly active carbon quantum dots according to claim 1, characterized in that: The S2 comprises the following steps: S21: pouring the mixed solution into a stirring container and stirring at 200 r / min for 3-5 min; S22: pouring the sodium hydroxide solution into the stirring container, controlling the stirring speed to 1000 r / min, and stirring for 15-30 min; S23: Adjust the pH value to 8-10, and simultaneously use ultrasonic means to homogenize the inside of the stirring container.

4. The method for preparing highly active carbon quantum dots according to claim 3, characterized in that: In S23, the frequency of ultrasonic treatment is controlled to be 35-45kHz, and the power is controlled to be 100W.

5. The method for preparing highly active carbon quantum dots according to claim 1, characterized in that: The S3 comprises the following steps: S31: putting the mixed solution homogenized in S2 into a microwave reaction device, setting the microwave power to 500-1000W, and controlling the reaction time to 20-40min; S32: During the reaction, glucose decomposes and carbonizes to form carbon quantum dots, while polyethylene glycol and Eu3+ ions modify the surface of carbon quantum dots and enhance their fluorescence, respectively; S33: After the reaction time is over, the microwave reaction device is left to stand.

6. The method for preparing highly active carbon quantum dots according to claim 1, characterized in that: The S4 comprises the following steps: S41: Cool the product to room temperature, transfer it to a centrifuge tube, put it into a centrifuge after balancing, and centrifuge it at 2000 r / min; S42: During centrifugation, the product settles at the bottom of the centrifuge tube, while impurities and unreacted products remain in the supernatant; S43: selecting deionized water, ethanol, or acetone as a washing liquid, and washing the centrifuged product with the washing liquid. During washing, shaking the centrifuge tube to allow the washing liquid to fully contact the product; S44: performing centrifugation again to remove the washing solution and residual impurities, and repeating the process 2-4 times until the washing solution becomes clear; S45: The washed product is taken out from the centrifuge tube, and then dried to obtain pure carbon quantum dots.

7. The method for preparing highly active carbon quantum dots according to claim 6, characterized in that: In S45, the drying process is performed by combining vacuum drying and freeze drying.

8. The method for preparing highly active carbon quantum dots according to claim 1, characterized in that: The S5 comprises the following steps: S51: Use high-energy electron beams to penetrate the sample, and use the scattered electrons generated by the collision between the electrons and the atoms in the sample to form an image, and use a transmission electron microscope to observe its shape, size and dispersion; S52: Using a nanoparticle size analyzer, the particle size distribution is inferred by measuring the fluctuation of the intensity of scattered light from particles in the sample; S53: Using a fluorescence spectrometer: measure the fluorescence intensity of the sample under different wavelengths of excitation light to determine the optimal excitation wavelength; S54: Measure fluorescence decay time using time-correlated single photon counting (TCSPC) technique.

9. A highly active carbon quantum dot, characterized in that: The highly active carbon quantum dots are prepared by the preparation method described in any one of claims 1 to 8.

10. An application of highly active carbon quantum dots, characterized in that: This includes the use of the highly active carbon quantum dots as described in claim 9 in the fields of aerospace, aviation, automobiles, electronics, machinery, and chemical industry.

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