Preparation method of highly active carbon quantum dots, highly active carbon quantum dots and applications

Abstract

The present invention provides a preparation method of high-activity carbon quantum dots, high-activity carbon quantum dots and applications, and relates to the technical field of carbon quantum dots, comprising the following steps: S1: glucose, polyethylene glycol and Eu 3+ ions are dissolved in deionized water to form a mixed solution; S2: under stirring conditions, sodium hydroxide solution is added to the mixed solution to adjust the pH value to obtain a mixed solution; S3: microwave reaction device is started, power and time are set; the present invention introduces surface modifier polyethylene glycol to accurately control the surface chemical properties of carbon quantum dots, improve their dispersibility and stability, and introduces fluorescence enhancer Eu 3+ ions, which improved the fluorescence quantum yield and fluorescence stability of carbon quantum dots. Glucose was used as the carbon source simultaneously, sodium hydroxide solution was added to adjust the pH, and the above-mentioned regulators were used for optimized synthesis, which improved the yield and reaction efficiency and achieved precise control of the particle size and morphology of carbon quantum dots.

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 remarkable fluorescent properties. These nanoparticles are composed of ultrafine, dispersed, quasi-spherical carbon nanoparticles with a size of less than 10nm. Carbon quantum dots have many advantages, such as excellent optical properties, good water solubility, low toxicity, environmental friendliness, wide raw material sources, low cost, and good biocompatibility. 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 raw material selection is limited in some cases; the arc discharge method has problems such as purification difficulties and low fluorescence efficiency. Overall, the carbon quantum dots prepared by the above preparation methods are not sufficiently active. In the prior art, for example, the authorization announcement No. CN114956052B discloses "Preparation method of high-activity carbon quantum dots, high-activity carbon quantum dots and applications", and specifically discloses: using aldehyde and base as core raw materials, forming carbon quantum dots by cross-linking polymerization, using a capping agent to regulate the particle size of the high-activity carbon quantum dots, and using an active agent to enhance the interfacial activity of the carbon quantum dots; however, in the above technology, the optimized 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, high-activity carbon quantum dots and applications. The preparation method of high-activity 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 solution: 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, and make the mixed solution undergo 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 includes the following steps:

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

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

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

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

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

[0018] S31: The mixed solution homogenized in S2 is placed in a microwave reaction apparatus, the microwave power is set to 500-1000W, and the reaction time is controlled 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 the 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 includes the following steps:

[0022] S41: Cool the product to room temperature, transfer it to a centrifuge tube, balance it, place it in a centrifuge, and centrifuge it at 2000 rpm;

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

[0024] S43: Select deionized water, ethanol, or acetone as a washing solution, and wash the centrifuged product with the washing solution. During washing, shake the centrifuge tube to ensure full contact between the washing solution and the product.

[0025] S44: Centrifuge again to remove the washing solution and residual impurities, and repeat 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 performed by combining vacuum drying and freeze drying.

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

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

[0030] S52: Using a nanoparticle size analyzer, the particle size distribution is inferred by measuring the fluctuations in 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: Fluorescence decay time was measured using time-correlated single photon counting (TCSPC) technology.

[0033] A highly active carbon quantum dot is prepared by adopting 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, automobiles, electronics, machinery, and chemical industry.

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

[0036] 1. The present invention introduces the surface modifier polyethylene glycol to precisely control the surface chemical properties of carbon quantum dots, thereby improving their dispersibility and stability. The fluorescence enhancer Eu3+ ions are introduced 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, the trinity 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 waves to homogenize the interior of the stirring vessel to improve mixing uniformity. During the microwave treatment, the power is controlled at 500-1000W and the reaction time is 20-40 minutes. It has been verified that this effectively ensures the stability of the reaction and avoids the situation where the reaction is violent and damages the equipment and raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Flowchart 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 with reference to the examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0040] Example 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 the following raw materials in 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. Dissolve the 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 a fluorescence enhancer, 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. The dosage 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 interior of the stirring container by ultrasonic means; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W. When adjusting the pH value, the method uses ultrasonic means to homogenize the interior of the stirring container 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 carbon quantum dot products. The steps specifically include: adding the mixed solution after S2 homogenization into the microwave reaction device, setting the microwave power to 500-1000W, and controlling the reaction time to 20-40 minutes; during the reaction process, glucose decomposes and carbonizes to form carbon quantum dots, while polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance their fluorescence; after the reaction time ends, the microwave reaction device is left to stand;

[0046] The microwave power setting has a significant impact on the reaction rate and product properties. Higher power can accelerate the reaction, but it can also cause the reaction to be too intense, producing undesirable byproducts or destroying the product structure. Therefore, set the microwave power to 500-1000W. Reaction time is also a key factor affecting product properties. 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 and other properties. Therefore, the reaction time is controlled to 20-40 minutes.

[0047] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, 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 supernatant; deionized water, ethanol, or acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to ensure that the washing liquid and the product are in full contact; 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 removed from the centrifuge tube and then dried to obtain pure carbon quantum dots, which are dried 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 by measuring the fluctuations in the intensity of scattered light from particles in the sample; using a fluorescence spectrometer to measure the fluorescence intensity of the sample under excitation light of different wavelengths 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 the analysis of 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 purified carbon quantum dots can be comprehensively evaluated, providing an important basis for their subsequent applications.

[0050] Example 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 the following raw materials in 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. Dissolve the 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 a fluorescence enhancer, 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. The dosage 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 interior of the stirring container by ultrasonic means; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W. When adjusting the pH value, the method uses ultrasonic means to homogenize the interior of the stirring container 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 carbon quantum dot products. The steps specifically include: adding the mixed solution after S2 homogenization into the microwave reaction device, setting the microwave power to 500-1000W, and controlling the reaction time to 20-40 minutes; during the reaction process, glucose decomposes and carbonizes to form carbon quantum dots, while polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance their fluorescence; after the reaction time ends, the microwave reaction device is left to stand;

[0056] The microwave power setting has a significant impact on the reaction rate and product properties. Higher power can accelerate the reaction, but it can also cause the reaction to be too intense, producing undesirable byproducts or destroying the product structure. Therefore, set the microwave power to 500-1000W. Reaction time is also a key factor affecting product properties. 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 and other properties. Therefore, the reaction time is controlled to 20-40 minutes.

[0057] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, 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 supernatant; deionized water, ethanol, or acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to ensure that the washing liquid and the product are in full contact; 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 removed from the centrifuge tube and then dried to obtain pure carbon quantum dots, which are dried 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 by measuring the fluctuations in the intensity of scattered light from particles in the sample; using a fluorescence spectrometer to measure the fluorescence intensity of the sample under excitation light of different wavelengths 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 the analysis of 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 purified carbon quantum dots can be comprehensively evaluated, providing an important basis for their subsequent applications.

[0060] Example 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 the following raw materials in 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. Dissolve the 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 a fluorescence enhancer, 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. The dosage 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 interior of the stirring container by ultrasonic means; controlling the frequency of the ultrasonic treatment to 35-45 kHz and the power to 100 W. When adjusting the pH value, the method uses ultrasonic means to homogenize the interior of the stirring container 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 carbon quantum dot products. The steps specifically include: adding the mixed solution after S2 homogenization into the microwave reaction device, setting the microwave power to 500-1000W, and controlling the reaction time to 20-40 minutes; during the reaction process, glucose decomposes and carbonizes to form carbon quantum dots, while polyethylene glycol and Eu3+ ions respectively modify the surface of the carbon quantum dots and enhance their fluorescence; after the reaction time ends, the microwave reaction device is left to stand;

[0066] The microwave power setting has a significant impact on the reaction rate and product properties. Higher power can accelerate the reaction, but it can also cause the reaction to be too intense, producing undesirable byproducts or destroying the product structure. Therefore, set the microwave power to 500-1000W. Reaction time is also a key factor affecting product properties. 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 and other properties. Therefore, the reaction time is controlled to 20-40 minutes.

[0067] After the reaction is completed, the product is cooled to room temperature. In order to speed up the cooling rate, a water bath, 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 supernatant; deionized water, ethanol, or acetone are selected as washing liquids, and the centrifuged product is washed with the washing liquid. During washing, the centrifuge tube is shaken to ensure that the washing liquid and the product are in full contact; 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 removed from the centrifuge tube and then dried to obtain pure carbon quantum dots, which are dried 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 by measuring the fluctuations in the intensity of scattered light from particles in the sample; using a fluorescence spectrometer to measure the fluorescence intensity of the sample under excitation light of different wavelengths 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 the analysis of 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 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 added with 3g of glucose as a capping agent and 6g of sodium p-aminosalicylate as an active agent, which were fully dissolved under stirring. Then, 25g of sodium hydroxide was added as an alkaline substance, and the reaction temperature was controlled at 60°C for 4 hours while stirring. After the reaction was completed, the mixture was allowed to stand for 24 hours, 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 conventional method were respectively prepared into 0.05 wt.% solutions and subjected to oil recovery tests. The recovery rate data obtained are shown in the following table:

[0075]

[0076] The present invention introduces surface modifier polyethylene glycol, accurately controls the surface chemical properties of carbon quantum dots, improves its dispersibility and stability, introduces fluorescence enhancer Eu3+ ions, improves the fluorescence quantum yield and fluorescence stability of carbon quantum dots, synchronously uses glucose as a carbon source, adds sodium hydroxide solution to regulate pH, and optimizes synthesis with the above-mentioned regulator, improves yield and reaction efficiency, achieves accurate regulation of carbon quantum dot particle size and morphology, in summary, adopts the mode of changing surface chemical properties, optimizing synthesis method and enhancing fluorescence performance trinity, so that the activity of carbon quantum dots is higher. And the present invention, when adjusting pH value, adopts ultrasonic means to homogenize the inside of the stirred vessel, improves the uniformity of its mixing, and in the process of microwave treatment, controls power 500-1000W and reaction time 20-40min. After verification, effectively ensure the stability of the reaction, avoid the situation that the reaction violently destroys the device and raw material.

[0077] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended 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, and make the mixed solution undergo 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 by 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, wherein: 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, wherein: 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: Pour the sodium hydroxide solution into the stirring container, control the stirring speed to 1000 r / min, and stir for 15-30 minutes; S23: Adjust the pH value to 8-10, and simultaneously use ultrasonic means to homogenize the interior of the stirring container.

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

5. The method for preparing highly active carbon quantum dots according to claim 1, wherein: The S3 includes the following steps: S31: The mixed solution homogenized in S2 is placed in a microwave reaction apparatus, the microwave power is set to 500-1000W, and the reaction time is controlled 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 the 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, wherein: The S4 comprises the following steps: S41: Cool the product to room temperature, transfer it to a centrifuge tube, balance it, place it in a centrifuge, and centrifuge it at 2000 rpm; S42: During centrifugation, the product settles at the bottom of the centrifuge tube, while impurities and unreacted substances remain in the supernatant; S43: Select deionized water, ethanol, or acetone as a washing solution, and wash the centrifuged product with the washing solution. During washing, shake the centrifuge tube to ensure that the washing solution is in full contact with the product. S44: Centrifuge again to remove the washing solution and residual impurities, and repeat 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, wherein: 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, wherein: 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 of electrons with atoms in the sample to form an image. Use transmission electron microscopy to observe its shape, size and dispersion. S52: Using a nanoparticle size analyzer, the particle size distribution is inferred by measuring the fluctuations in 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: Fluorescence decay time was measured using time-correlated single photon counting (TCSPC) technology.

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

10. An application of highly active carbon quantum dots, characterized by: 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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