Preparation method of ultrastrong dispersibility and high stability and catalytic activity carbon quantum dots and application thereof
The preparation of carbon quantum dots by a solvothermal method solves the problem of poor photoelectric response in existing technologies, realizes the extension of the spectral response boundary to the visible light region and efficient photocatalytic reaction, and prepares carbon quantum dots with super-strong dispersibility and high stability and high catalytic activity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2026-06-26
AI Technical Summary
Carbon quantum dots prepared by existing solvothermal methods have poor photoelectric response capabilities, only responding to ultraviolet light, and cannot achieve efficient photocatalytic reactions on their own.
Carbon quantum dot precursors such as L-ascorbic acid, glucose, cellulose, citric acid monohydrate, citric acid, urea, L-glutamic acid, and m-phenylenediamine are used to form carbon quantum dots through solvothermal treatment. These carbon quantum dots are then combined with water or organic solvents, and the reaction conditions, such as temperature and time, are controlled. After multiple washing and drying processes, carbon quantum dots with super dispersibility and high stability are obtained.
The spectral response boundary of carbon quantum dots extends into the visible light region. They can completely decompose target pollutants within 2 hours under simulated sunlight, maintain good dispersibility for several months, are suitable for water and ethanol solutions, and are stable in the pH range of 4-12.
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Abstract
Description
Technical Field
[0001] This application relates to a method for preparing highly catalytically active carbon quantum dots with strong dispersibility and stability, and their applications, belonging to the field of quantum dots. Background Technology
[0002] Quantum dots are nanoscale semiconductor particles. Due to the quantum confinement effect, the movement of electrons and holes is restricted at such a small size, resulting in energy level discretization and thus unique photoelectric properties. Carbon quantum dots, often simply called carbon dots, are a member of the quantum dot nanomaterial family and have also demonstrated unique appeal. Compared to other quantum dots, carbon quantum dots exhibit excellent biocompatibility and are completely non-toxic and harmless to the environment. Furthermore, their optical and electronic properties can be tuned by changing their particle size. Therefore, carbon quantum dots play an important role in photoelectrocatalysis, biomedicine, and energy storage.
[0003] In the energy sector, the photoelectric conversion properties of carbon quantum dots are primarily utilized to produce green energy. Generally, the synthesis methods for these carbon quantum dots are divided into two main approaches: "top-down" and "bottom-up." The "top-down" strategy mainly consists of laser ablation, chemical oxidation, and ultrasonic methods. Although this strategy can synthesize high-purity carbon quantum dots with highly controllable particle size, its complex operation, high cost, and requirement for specific equipment greatly limit the development of carbon quantum dots. Common "bottom-up" synthesis strategies include thermal decomposition, microwave synthesis, and hydrothermal treatment. Among these, hydrothermal treatment is the main route for the synthesis of most carbon quantum dots, which involves mixing carbon-based compounds with inorganic or organic solutions and preparing them under high-temperature catalysis. This synthesis method can effectively reduce costs and efficiently control various parameters during the synthesis process, but the carbon quantum dots produced by this process have poor photoelectric response and can only respond to the ultraviolet region of the solar spectrum. Furthermore, the carbon quantum dots synthesized by this process cannot undergo photocatalytic reactions independently. Currently, almost all photocatalytic decomposition processes involving carbon quantum dots cannot be completed by carbon quantum dots alone, as shown in DOI:10.1039 / D1NJ02387J, DOI:org / 10.1016 / j.cej.2021.133927, DOI:org / 10.1016 / j.cej.2019.123016, etc. The decomposition process is even achieved by loading carbon quantum dots onto catalysts containing heavy metals, such as DOI:org / 10.1016 / j.seppur.2022.122333. This is due to the poor photoelectric response of carbon quantum dots themselves. These limitations significantly restrict the application of carbon quantum dots in photoelectric energy conversion and environmental remediation. Summary of the Invention
[0004] This invention aims to address the poor photoelectric response characteristics of carbon quantum dots prepared by the solvothermal method, which only respond to ultraviolet light and cannot achieve efficient photocatalytic reactions independently. Therefore, it provides a method for preparing carbon quantum dots with ultra-high stability and excellent photocatalytic activity. The preparation method disclosed in this invention successfully extends the absorption boundary of carbon quantum dots from the ultraviolet region to the visible light region, achieving a high absorption rate under simulated sunlight intensity (100 mW / cm²). 2 Under these conditions, the target pollutant (methylene blue) can be almost completely decomposed within 2 hours. These carbon quantum dots exhibit excellent dispersibility in both aqueous and ethanol solutions, remaining non-aggregating for months, and maintaining excellent dispersibility within a pH range of 4–12.
[0005] According to the first aspect of this application, a method for preparing highly dispersible and stable catalytically active carbon quantum dots is provided. Various carbon sources are added to water or an aqueous organic solvent to form a carbon quantum dot precursor solution. The precursor solution is then subjected to aqueous or solvothermal treatment, followed by separation, and multiple washing and drying steps to obtain highly dispersible and stable catalytically active carbon quantum dots.
[0006] A method for preparing highly catalytically active carbon quantum dots with superior dispersibility and stability, the method comprising:
[0007] A homogeneous solution containing carbon quantum dot precursors, water, and organic solvents is placed in a sealed container and reacted to obtain carbon quantum dots.
[0008] The carbon quantum dot precursor is selected from at least one of L-ascorbic acid, glucose, cellulose, citric acid monohydrate, citric acid, urea, L-glutamic acid, and m-phenylenediamine.
[0009] In this application, the carbon quantum dot precursors are selected from L-ascorbic acid, glucose, cellulose, citric acid monohydrate, citric acid, urea, L-glutamic acid, and m-phenylenediamine. These carbon quantum dot precursors decompose under high-temperature conditions, subsequently undergoing carbonization to form carbon quantum dots. These precursors have moderate molecular weights, and under high-temperature conditions, they can pyrolyze into smaller molecular chain segments, which helps to form carbon quantum dots with uniform particle size. The abundant hydroxyl and carboxyl functional groups in these precursors effectively enhance the electron transitions and light absorption of the carbon quantum dots. These precursors all contain hydrophilic functional groups such as hydroxyl, carboxyl, or amino groups to varying degrees, which further improve the stability of carbon quantum dots in aqueous and alcoholic solutions.
[0010] Optionally, the organic solvent is selected from at least one of ethanol, ethylene glycol, isopropanol, dimethylformamide, triethanolamine, ethylenediamine, diethylenetriamine, and diethanolamine.
[0011] Optionally, the method for obtaining the homogeneous solution containing carbon quantum dot precursor, water, and organic solvent includes:
[0012] Carbon quantum dot precursors are added to water to form a carbon quantum dot precursor solution, and then an organic solvent is added and stirred until homogeneous.
[0013] Optionally, the molar concentration of the carbon quantum dot precursor in the carbon quantum dot precursor solution is 0.05 to 0.5 mol / L.
[0014] Optionally, the molar concentration of the carbon quantum dot precursor is independently selected from any value or a range between 0.05 mol / L, 0.07 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, and 0.5 mol / L.
[0015] Optionally, the volume ratio of the organic solvent to the carbon quantum dot precursor solution is 1:200 to 1:1.
[0016] Optionally, the volume ratio of the organic solvent to the carbon quantum dot precursor solution is independently selected from any value or a range between 1:200, 1:180, 1:160, 1:150, 1:140, 1:120, 1:100, 1:80, 1:60, 1:50, 1:40, 1:20, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, and 1:1.
[0017] Optionally, the reaction conditions are: temperature of 180–240°C and time of 4–12 hours.
[0018] Optionally, the reaction temperature is independently selected from any value of 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or a range between any two.
[0019] Optionally, the reaction time is independently selected from any value of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or a range between any two.
[0020] Optionally, after the reaction is complete, the steps of centrifugation, washing, and drying are also included.
[0021] As a preferred embodiment, a method for preparing highly catalytically active carbon quantum dots with strong dispersibility and stability includes:
[0022] Step 1: Add the carbon quantum dot precursor to water to form a carbon quantum dot precursor solution with a molar concentration range of 0.05 to 0.5 mol / L;
[0023] Step 2: Add an appropriate amount of organic solvent to the solution obtained in Step 1 and stir for 30 minutes to form a homogeneous solution;
[0024] Step 3: After the solution obtained in Step 3 is stirred evenly, it is transferred to a high-pressure reactor with a polytetrafluoroethylene liner for solvent heat treatment at a temperature of 180-240°C for 4-12 hours.
[0025] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain highly dispersible and highly stable high-fluorescent carbon quantum dot powder.
[0026] According to a second aspect of this application, a method described above is provided for preparing carbon quantum dots.
[0027] The carbon quantum dots prepared by the method described above.
[0028] Optionally, the average size of the carbon quantum dots is around 5 nm.
[0029] This carbon quantum dot material maintains excellent dispersibility within a pH range of 4-12. It can remain highly dispersed and non-settling in water or anhydrous ethanol for several months.
[0030] According to a third aspect of this application, an application is provided for the carbon quantum dots prepared by the above-described preparation method in the photocatalytic decomposition of pollutants. Because their spectral response boundary extends into the visible light region, they can achieve highly efficient photocatalytic reactions independently, thus enabling almost complete decomposition of pollutants under simulated sunlight irradiation.
[0031] Application of carbon quantum dots prepared by the above-described method in the photocatalytic decomposition of pollutants.
[0032] Alternatively, carbon quantum dots can be used alone under sunlight.
[0033] The beneficial effects that this application can produce include:
[0034] This application provides a method for preparing highly dispersible and stable carbon quantum dots with high catalytic activity, and its application. The prepared carbon quantum dots exhibit excellent dispersibility, stability, and catalytic activity. These carbon quantum dots demonstrate excellent dispersibility in both aqueous and ethanol solutions, remaining stable for several months without aggregation, and maintaining excellent dispersibility within a pH range of 4–12. The absorption boundary of these carbon quantum dots extends from the ultraviolet region to the visible light region, enabling them to achieve highly efficient photocatalytic reactions independently, even under simulated solar light intensity (100 mW / cm²). 2 Under controlled conditions, the target pollutant (methylene blue) can be almost completely decomposed within 2 hours. The synthesis process of this carbon quantum dot is green and environmentally friendly, with controllable conditions, and has potential for large-scale preparation and pollution control. Attached Figure Description
[0035] Figure 1 HRTEM image (a) and lattice spacing (b) of the carbon quantum dot powder prepared in Example 1;
[0036] Figure 2 The ultraviolet-visible (UV-Vis) spectrum of the carbon quantum dot powder prepared in Example 1;
[0037] Figure 3 The dispersion of carbon quantum dot powder prepared in Example 1 in solutions with pH 4-12, from left to right, is as follows: pH = 4, 5, 6, 7, 8, 9, 10, 11, 12.
[0038] Figure 4 The image shows a comparison of the carbon quantum dot powder prepared in Example 1 before and after 3 months in aqueous and alcoholic solutions. The left side shows the aqueous solution, and the right side shows the ethanol solution. The top image shows the state before 3 months, and the bottom image shows the state after 3 months.
[0039] Figure 5 The graph shows the degradation curve of methylene blue corresponding to the carbon quantum dot powder prepared in Example 1 under simulated sunlight irradiation. The middle graph shows the color change of the methylene blue solution every half hour.
[0040] Figure 6 The degradation curves of methylene blue corresponding to the carbon quantum dot powders prepared in Example 1, Comparative Examples 1 and 2 under simulated sunlight irradiation are shown. Detailed Implementation
[0041] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0042] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0043] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0044] Cellulose was purchased from Sigma, specification C6288.
[0045] Microcrystalline cellulose was purchased from Sigma, specification 310697.
[0046] The analysis method in the embodiments of this application is as follows:
[0047] The morphology analysis of carbon quantum dots was performed using a Talos F200S instrument, after the carbon quantum dots were dispersed in water at a ratio of 50 times.
[0048] The instrument used for the ultraviolet-visible spectroscopy analysis of carbon quantum dots was a Lambda 1050+, with a scanning range of 250–800 nm.
[0049] Example 1
[0050] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0051] Step 1: Add L-ascorbic acid to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.05 mol / L.
[0052] Step 2: Slowly add 20 ml of anhydrous ethanol to the 20 ml carbon quantum dot precursor solution from Step 1, and stir at room temperature for 30 min.
[0053] Step 3: After step 2, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 180°C, and maintain the temperature for 6 hours.
[0054] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0055] Example 2
[0056] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0057] Step 1: Add glucose to the aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.07 mol / L.
[0058] Step 2: After step 1 is completed, slowly add 5 ml of dimethylformamide to the 15 ml carbon quantum dot precursor solution in step 1 and stir at room temperature for 30 min.
[0059] Step 3: Transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 180°C, and maintain the temperature for 4 hours;
[0060] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0061] Example 3
[0062] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0063] Step 1: Add citric acid monohydrate to the aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.1 mol / L.
[0064] Step 2: Slowly add 450 μL of diethylenetriamine to 10 ml of carbon quantum dot precursor solution from Step 1, and stir at room temperature for 30 min.
[0065] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 220°C, and maintain the temperature for 5 hours.
[0066] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0067] Example 4
[0068] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0069] Step 1: Add L-ascorbic acid to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.3 mol / L.
[0070] Step 2: Slowly add 15 ml of ethylene glycol to the 20 ml carbon quantum dot precursor solution from Step 1, and stir at room temperature for 30 min;
[0071] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 160°C, and maintain the temperature for 7 hours.
[0072] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain highly dispersible and highly stable high-fluorescent carbon quantum dot powder.
[0073] Example 5
[0074] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0075] Step 1: Add citric acid (5 g) and urea (1 g) to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 min to completely dissolve it;
[0076] Step 2: After step 1 is completed, slowly add 15 ml of isopropanol to the 15 ml carbon quantum dot precursor solution in step 1, and stir at room temperature for 30 min.
[0077] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 200°C, and maintain the temperature for 12 hours.
[0078] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0079] Example 6
[0080] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0081] Step 1: Add m-phenylenediamine (0.4 g) and L-glutamic acid (7 g) to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 min to completely dissolve it;
[0082] Step 2: After step 1 is completed, slowly add 5 ml of triethanolamine to the 5 ml carbon quantum dot precursor solution in step 1 and stir at room temperature for 30 min.
[0083] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 220°C, and maintain the temperature for 6 hours.
[0084] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0085] Example 7
[0086] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0087] Step 1: Add citric acid to the aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.5 mol / L.
[0088] Step 2: Slowly add 330 μL of ethylenediamine to the 20 mL carbon quantum dot precursor solution from Step 1 and stir at room temperature for 30 min.
[0089] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 190°C, and maintain the temperature for 5 hours.
[0090] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0091] Example 8
[0092] A method for preparing carbon quantum dots with superior dispersibility and stability and high catalytic activity is described below:
[0093] Step 1: Add cellulose to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes until completely dissolved. The molar concentration of the solution is 0.2 mol / L;
[0094] Step 2: Slowly add 100 μL of ethylenediamine to the 20 mL carbon quantum dot precursor solution from Step 1, and stir at room temperature for 30 min.
[0095] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 240°C, and maintain it for 12 hours.
[0096] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0097] Comparative Example 1
[0098] Step 1: Add microcrystalline cellulose to an aqueous solution to prepare a carbon quantum dot precursor solution, and stir at room temperature for 30 minutes to ensure complete dissolution. The molar concentration of the solution is 0.4 mol / L.
[0099] Step 2: Slowly add 100 μL of diethanolamine to the 15 ml carbon quantum dot precursor solution from Step 1, and stir at room temperature for 30 min.
[0100] Step 3: After step 2 is completed, transfer the solution to a polytetrafluoroethylene stainless steel high-pressure reactor, heat it to 210°C, and maintain it for 12 hours.
[0101] Step 4: Collect the carbon quantum dots obtained after step 3 by centrifugation, wash the product three times each with water and ethanol, and dry the product overnight in a vacuum drying oven at 60°C to obtain carbon quantum dot powder.
[0102] Comparative Example 2
[0103] The procedure is the same as in Example 6, except that triethanolamine is replaced with water to obtain carbon quantum dot powder.
[0104] Characterization test
[0105] The carbon quantum dot powder prepared in the above embodiments was characterized and tested.
[0106] Taking the carbon quantum dot powder prepared in Example 1 as an example, its electron micrograph is as follows: Figure 1 As shown, Figure (a) is an HRTEM image, and Figure (b) shows the lattice spacing. It can be seen that the average size of the carbon quantum dots is about 5 nm, and the lattice spacing d = 0.21 nm, indicating that the prepared nanomaterial is carbon quantum dots.
[0107] Taking the carbon quantum dot powder prepared in Example 1 as an example, its ultraviolet-visible (UV-Vis) spectrum is as follows: Figure 2 As shown, this demonstrates the successful extension of the absorption boundary of carbon quantum dots from the ultraviolet region to the visible light region.
[0108] Using the carbon quantum dot powder prepared in Example 1 as an example, solutions with pH values of 4, 5, 6, 7, 8, 9, 10, 11, and 12 were prepared respectively (the preparation method was to dilute concentrated ammonia water with a mass fraction of 25-28% to the corresponding pH value). 50 mg of carbon quantum dot powder was added to each solution, and the dispersion was as follows. Figure 3 As shown, the solution is clear and transparent, indicating that the carbon quantum dots maintain excellent dispersibility within the pH range of 4-12.
[0109] Taking the carbon quantum dot powder prepared in Example 1 as an example, 50 mg of carbon quantum dot powder was added to both aqueous and alcoholic solutions, and its state changes were observed after 3 months. Figure 4 As shown, the left side represents an aqueous solution, and the right side represents an ethanol solution; the top image is from 3 months ago, and the bottom image is from 3 months later. It can be seen that the solutions remain transparent and clear in both aqueous and ethanol solutions, indicating that the carbon quantum dots exhibit excellent dispersibility in both solutions without aggregation over several months.
[0110] Taking the carbon quantum dot powder prepared in Example 1 as an example, under simulated sunlight irradiation (100mW / cm²), 2 At this point, 10 mg of carbon quantum dot powder was added to a methylene blue solution with an initial concentration of 1 mg / L. The changes in concentration and color were tested and compared with the self-degradation of the methylene blue solution. Figure 5 As shown, the target pollutant (methylene blue) can be almost completely decomposed within 2 hours. Compared with Comparative Example 1 and Comparative Example 2, as shown... Figure 6 As shown, the degradation results compared with those of Comparative Examples 1 and 2 demonstrate that the carbon quantum dots prepared in Example 1 have excellent photocatalytic activity.
[0111] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for preparing highly catalytically active carbon quantum dots with superior dispersibility and stability, characterized in that, The preparation method includes: A homogeneous solution containing carbon quantum dot precursors, water, and organic solvents is placed in a sealed container and reacted to obtain carbon quantum dots. The carbon quantum dot precursor is selected from at least one of L-ascorbic acid, glucose, cellulose, citric acid monohydrate, citric acid, urea, L-glutamic acid, and m-phenylenediamine.
2. The preparation method according to claim 1, characterized in that, The organic solvent is selected from at least one of ethanol, ethylene glycol, isopropanol, dimethylformamide, triethanolamine, ethylenediamine, diethylenetriamine, and diethanolamine.
3. The preparation method according to claim 1, characterized in that, The method for obtaining the homogeneous solution containing carbon quantum dot precursor, water, and organic solvent includes: Carbon quantum dot precursors are added to water to form a carbon quantum dot precursor solution, and then an organic solvent is added and stirred until homogeneous.
4. The preparation method according to claim 3, characterized in that, The carbon quantum dot precursor solution has a molar concentration of 0.05–0.5 mol / L.
5. The preparation method according to claim 3, characterized in that, The volume ratio of the organic solvent to the carbon quantum dot precursor solution is 1:200 to 1:
1.
6. The preparation method according to claim 1, characterized in that, The reaction conditions are: temperature 180–240°C, time 4–12 hours.
7. The preparation method according to claim 1, characterized in that, After the reaction is complete, the steps also include centrifugation, washing, and drying.
8. Carbon quantum dots prepared by the preparation method according to any one of claims 1 to 7.
9. The application of carbon quantum dots prepared by the preparation method according to any one of claims 1 to 7 in the photocatalytic decomposition of pollutants.
10. The application according to claim 9, characterized in that, Carbon quantum dots used alone under sunlight.