A rapid method for detecting bromomethane

Abstract

This invention discloses a rapid method for detecting bromomethane, comprising the following steps: First, a nucleophilic reagent is added to a bromomethane-containing base solution, and the reaction generates free bromide ions under ultraviolet irradiation; then, CsPbCl3 quantum dots are introduced to react, and the color change information of the resulting solution or the rightward shift information of the fluorescence peak position at 410–520 nm in the solution system is obtained, so as to achieve visual detection of bromomethane. The CsPbCl3 quantum dots introduced in this invention can directly react with the bromide ions formed by the conversion of bromomethane, inducing changes in the color information of the fluorescent solution or the fluorescence peak position, without the need for an additional intermediate response medium; and the corresponding fluorescence emission peak position and fluorescence color response mechanism are relatively stable and highly sensitive, providing a new approach for the high-sensitivity detection of bromomethane and other bromine-based compounds; moreover, the detection method is relatively simple and easy to operate, making it suitable for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis and detection technology, specifically relating to a perovskite quantum dot-mediated visual fluorescence sensing method for detecting bromomethane in tea. Background Technology

[0002] Methyl bromide has strong fumigation and osmotic properties and is commonly used for fumigating goods and perishable items before storage. It is widely used in warehouse disinfection, port quarantine, and other fields. Although methyl bromide is highly volatile, residual methyl bromide can persist in food. Therefore, developing a rapid, accurate, and sensitive method for detecting methyl bromide in tea has significant practical value and real-world implications.

[0003] Methyl bromide is an excellent methylating agent, reacting with organic compounds containing active hydrogen in food matrices to form corresponding methylated products, leading to the residue of inorganic bromide ions in food. Therefore, the bromide ion content is sometimes used as an indicator of methyl bromide fumigation residues. Common methods for detecting methyl bromide in food mainly include titration, spectrophotometry, headspace gas chromatography, and gas chromatography-mass spectrometry. However, most of these methods rely on large and medium-sized instruments, are time-consuming, expensive, involve complex sample pretreatment processes, and require specialized technicians, making it difficult to quickly, timely, and accurately monitor and assess the residual amount of methyl bromide in tea. Summary of the Invention

[0004] The main objective of this invention is to address the shortcomings of existing technologies by providing a method for detecting bromomethane using perovskite quantum dots. First, a nucleophilic reagent reacts with bromomethane to form bromide ions. Then, CsPbCl3 quantum dots are introduced, inducing a rightward shift in the fluorescence emission peak position and a change in the solution's fluorescence color, thereby achieving visual detection of bromomethane. This method has advantages such as simple operation, fast response, high sensitivity, and rich color changes, enabling rapid, quantitative, and visual identification of bromomethane in base liquids such as tea, and is suitable for widespread application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A rapid method for detecting bromomethane involves first adding a nucleophilic reagent to a base solution containing bromomethane, and then conducting a secondary nucleophilic substitution reaction under ultraviolet irradiation to generate free bromide ions. Next, CsPbCl3 quantum dots are introduced to carry out the reaction, and the color change information of the resulting solution or the rightward shift of the fluorescence peak position at 410–520 nm in the solution system is obtained to achieve visual detection of bromomethane.

[0007] Furthermore, the method for rapid detection of bromomethane specifically includes the following steps:

[0008] 1) Add a nucleophile to a base solution containing bromomethane to induce a secondary nucleophilic substitution reaction of bromomethane (S... N 2) The reaction produces free bromide ions, which are then diluted to obtain bromide ion solutions of different concentrations.

[0009] 2) Mix bromide ion solutions of different concentrations with CsPbCl3 quantum dot dispersions and react them to obtain the relationship between bromide ion concentration and the color change of the solution before and after the reaction or the rightward shift of the fluorescence emission peak position, so as to realize the quantitative or semi-quantitative detection of bromomethane.

[0010] In the above scheme, in step 2), the relationship between bromide ion concentration and solution color change before and after the reaction is obtained. Based on the solution color change, the level of bromomethane content in the solution system is determined, thereby achieving semi-quantitative detection of bromomethane.

[0011] Furthermore, as the content of bromomethane (chloride ions) increases, the resulting solution system changes color sequentially from purple to blue to green.

[0012] In the above scheme, in step 2), the relationship between bromide ion concentration and the color change of the solution before and after the reaction or the rightward shift of the fluorescence emission peak position is obtained, and a linear regression equation is established between the rightward shift of the fluorescence emission peak position in the fluorescence spectrum and the concentration of bromomethane to achieve quantitative detection of bromomethane content.

[0013] In the above scheme, the changes in fluorescence color and the rightward shift of the fluorescence emission peak position are observed or measured under ultraviolet lamp irradiation (320-400nm).

[0014] Furthermore, the fluorescence spectroscopy measurement conditions are all: emission wavelength of 400-600 nm, excitation wavelength of 350-420 nm, and slit width of 10-15 nm.

[0015] Furthermore, the information regarding the rightward shift of the fluorescence emission peak position represents the change in peak position before and after the reaction.

[0016] In the above scheme, the nucleophile can be an amine, thiol, or thiourea nucleophile.

[0017] Furthermore, the nucleophile may specifically be oleylamine, octylamine, hexylamine, 2-mercaptoethanol, 4-mercaptobutanol, thiourea, or N-methylthiourea, etc.

[0018] In the above scheme, the base liquid containing bromomethane can be selected from organic solvents such as cyclohexane, ethanol, diethyl ether, or chloroform.

[0019] In the above scheme, the ultraviolet lamp used for ultraviolet irradiation has a wavelength of 254-365nm and a power of 15-30W.

[0020] Furthermore, the distance between the irradiation lamp source and the reaction solution EP tube is 10–20 cm.

[0021] Furthermore, the target of this invention, bromomethane, has a symmetrical molecular structure with a C-Br bond energy as high as 293 kJ / mol. Under normal conditions, the chemical bonds are not easily broken, exhibiting high chemical stability. A weak secondary nucleophilic substitution reaction can occur between bromomethane and the nucleophile. Introducing ultraviolet radiation can effectively lower the activation energy of the reaction and promote its selectivity, ensuring a complete secondary nucleophilic substitution reaction and effectively guaranteeing the conversion efficiency of bromomethane and the final detection result.

[0022] In the above scheme, the molar ratio of bromomethane to nucleophile is 1:1 to 2.

[0023] In the above scheme, the secondary nucleophilic substitution reaction is carried out at room temperature for a reaction time of 20–60 s.

[0024] In the above scheme, the concentration of bromide ions in the bromide ion solution obtained in step 1) is 0.1 to 120 ppb.

[0025] In the above scheme, the concentration of CsPbC13 quantum dots in the CsPbC13 quantum dot dispersion is 1-5 mM.

[0026] Furthermore, the solvent used in the CsPbC13 quantum dot dispersion is cyclohexane or the like.

[0027] In the above scheme, the reaction time after adding the CsPbC13 quantum dot dispersion is 5 to 15 minutes.

[0028] In the above scheme, the volume ratio of the CsPbCl3 quantum dot solution to the bromide ion solution is 1:1 to 4.

[0029] In the above scheme, the preparation method of CsPbC13 quantum dots is as follows:

[0030] (1) Weigh out Cs salt and mix with OA (oleic acid), heat and dissolve to prepare Cs precursor solution; weigh out Pb salt, 1-ODE (1-octadecene), 4-chlorobutyric acid and OAM (oleylamine), mix and heat and dissolve to prepare Pb precursor solution;

[0031] (2) The Cs precursor solution was rapidly injected into the Pb precursor solution for reaction, and the reaction solution was rapidly cooled by an ice bath to obtain the crude product Cs4PbCl6 NPs. After washing, white Cs4PbCl6 NPs solid was obtained.

[0032] (3) The obtained white Cs4PbCl6 NPs solid was dispersed in an organic solvent and water was rapidly injected under shaking conditions. The mixture was shaken, allowed to stand for 12-24 hours, and then centrifuged to remove the bottom phase precipitate, thus obtaining CsPbCl3 quantum dots.

[0033] In the above scheme, the Cs salt can be Cs2CO3 or CsCl2, etc.; the Pb can be PbCl2, etc.

[0034] In the above scheme, the heating and melting temperature is 150-200℃, and the time is 1-2 hours.

[0035] Preferably, the concentration of Cs ions in the Cs precursor solution is 0.6–1 mol / L.

[0036] Preferably, in the Pb precursor solution, the molar ratio of Pb salt, 4-chlorobutyric acid, and OAm is 1:55-65:115-125.

[0037] Furthermore, this invention utilizes ligands such as 4-chlorobutyric acid to chelate onto the surface of CsPbX3 crystals at multiple ends, anchoring one end and providing a corresponding surface charge at the other end; additionally, the anionic and cationic groups therein cannot be... Acid-base balance mutual neutralization or external neutralization can avoid ligand dissociation caused by proton exchange reaction, improve the stability of quantum dots, promote a more stable reaction with bromide ions, and achieve stable and highly sensitive changes in the position and color of fluorescence emission peaks.

[0038] Furthermore, the Pb ion concentration in the Pb precursor solution is 1–10 mM.

[0039] Preferably, the volume ratio of the Cs precursor solution to the Pb precursor solution is 1:20 to 25.

[0040] Furthermore, the injection time of the Cs precursor solution is 2 to 5 seconds.

[0041] In the above scheme, the organic solvent can be cyclohexane or ethanol, etc.

[0042] In the above scheme, the reaction time in step (2) is 10 to 20 seconds.

[0043] In the above scheme, in step (2), an ice bath is used to rapidly cool the solution to room temperature within 3 to 5 minutes.

[0044] In the above scheme, the oscillation step uses an oscillation rate of 1000-3000 rpm; the oscillation processing time is 1-3 min.

[0045] Preferably, the volume ratio of cyclohexane to water added in step (3) is 10 to 15:1.

[0046] Furthermore, the water injection time is 2 to 3 seconds.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1) This invention is the first to propose a method for detecting bromomethane, which uses ultraviolet photocatalysis to promote the attack of nucleophiles on C-Br in bromomethane, converting it into bromide ions efficiently and completely; then, a fluorescent probe CsPbCl3 quantum dots with high chemical stability, high photostability and low toxicity is introduced, which can react with bromide ions in the base solution, causing the fluorescence emission peak of CsPbCl3 quantum dots to shift to the right and the color of the fluorescent solution to change, thus achieving efficient and convenient detection of bromomethane and other bromine compounds;

[0049] 2) The CsPbCl3 quantum dots introduced in this invention react directly with bromide ions formed by the conversion of bromomethane (without the need for an additional intermediate response medium), inducing changes in the color information of the fluorescent solution or the position of the fluorescence peak; and the corresponding fluorescence emission peak position and fluorescence color response mechanism are relatively stable and highly sensitive, which can provide a new approach for the high-sensitivity detection of bromomethane and other bromo compounds.

[0050] 3) This invention provides a sensitive fluorescence platform for the determination of methyl bromide in tea. It has high accuracy, high sensitivity, and good linear range. Compared with existing detection methods, it avoids the defects of large equipment and long time consumption. Moreover, it does not require high professional skills from operators, has wide applicability, and has great application potential. Attached Figure Description

[0051] Figure 1 The fluorescence spectrum of CsPbCl3 quantum dots prepared in this invention;

[0052] Figure 2 Transmission electron microscope image of CsPbC13 quantum dots prepared for this invention;

[0053] Figure 3 This is a schematic diagram of the brominated methane detection method described in this invention.

[0054] Figure 4 The images show the CsPbCl3 quantum dots described in Example 1 of this invention and their fluorescence spectra after reaction with methyl bromide (CH3Br) and oleylamine (OA), respectively.

[0055] Figure 5The following are graphs showing the relationship between the rightward shift of the fluorescence peak position of CsPbCl3 quantum dots after reacting with CsPbCl3 quantum dots, bromomethane (CH3Br), and oleylamine (OA) as described in Example 1 of this invention: (a) a graph showing the relationship between the concentration of bromomethane and the fluorescence peak position of CsPbCl3 quantum dots after the reaction with bromomethane; (b) a graph showing the linear fitting error bar analysis of the concentration range of 0.333ppb-0.667ppb, where the horizontal axis represents the concentration of bromomethane and the vertical axis represents the difference between the fluorescence peak position of CsPbCl3 quantum dots after the addition of bromomethane and the initial fluorescence peak position of CsPbCl3 quantum dots; (c) a graph showing the linear fitting error bar analysis of the concentration range of 0.067ppb-0.400ppb, where the horizontal axis represents the concentration of bromomethane and the vertical axis represents the difference between the fluorescence peak position of CsPbCl3 quantum dots after the addition of bromomethane and the initial fluorescence peak position of CsPbCl3 quantum dots; and (d) a graph showing the color change of the fluorescence color of CsPbCl3 quantum dots as described in Example 1 of this invention. Detailed Implementation

[0056] The applicant will now provide a more detailed description of the present invention with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. However, the following content should not be construed as limiting the scope of protection claimed in the claims of the present invention.

[0057] All chemical reagents and solvents used in the examples were of analytical grade.

[0058] The fluorescence spectroscopy measurement conditions were all for an emission wavelength of 400-600 nm, an excitation wavelength of 365 nm, and a slit width of 10-15 nm.

[0059] The preparation method of the CsPbC13 quantum dot dispersion includes the following steps:

[0060] 1) Weigh 0.166 g Cs2CO3 (1.02 mmol) and mix with 2 mL OA in a round-bottom flask, and incubate in an oil bath at 160 °C for 1 hour to completely dissolve the solid metal salt, in order to prepare a Cs precursor solution; at the same time, weigh 0.014 g PbCl2 (0.05 mmol) and mix with 10 mL 1-ODE, 300 μL CBA (3.04 mmol) and 2.0 mL OAm (6.08 mmol) in a round-bottom flask, and incubate in an oil bath at 160 °C for 1 hour to completely dissolve the solid metal salt, in order to prepare a Pb precursor solution;

[0061] 2) 550 μL of Cs precursor solution was rapidly injected into Pb precursor solution, and the reaction was allowed to proceed for about 15 seconds. The reaction solution was then rapidly cooled using an ice bath to obtain crude Cs4PbCl6 NPs. The crude product was washed twice with 1-ODE and n-hexane (9000 rpm, 10 min) to obtain pure white Cs4PbCl6 NPs solid, which was then dispersed in 25 ml of cyclohexane.

[0062] 3) Rapidly inject 200 μL of deionized water under vigorous shaking (2000 rpm) and shake for 5 min. Keep the reaction system undisturbed for 12 h under the environment. Then centrifuge at 9500 rpm for 5 min to remove the bottom phase precipitate and obtain CsPbCl3 dispersion (concentration of 2 mM).

[0063] The obtained CsPbCl3 quantum dots (initial peak position at 410 nm, see...) Figure 1 Transmission electron microscopy characterization revealed that the obtained product consisted of uniformly dispersed spherical particles (see...). Figure 2 ).

[0064] Example 1

[0065] A rapid method for detecting methyl bromide in tea leaves includes the following steps:

[0066] 1) Dilute 1.0 ml of bromomethane in 10 ml of cyclohexane, add 3 ml of oleylamine to the solution, mix well, and react under a UV lamp with an excitation wavelength of 365 nm and a power of 20 W for 40 s to allow the bromomethane to undergo a secondary nucleophilic substitution reaction (S2). N 2) The reaction produces free bromide ions, and then the resulting bromide ion solution is diluted to a bromide ion concentration range of 0.1-120 ppb;

[0067] 2) 80 μL of bromide ion solutions of different concentrations (0.667 ppb, 0.600 ppb, 0.500 ppb, 0.400 ppb, 0.333 ppb, 0.267 ppb, 0.200 ppb, and 0.133 ppb, respectively) were mixed with 50 μL of CsPbCl3 quantum dots to obtain solution II. The reaction was carried out at room temperature for 5 min. The color change of the solution after adding different concentrations of bromomethane under ultraviolet light irradiation was observed visually. The relationship between the color change and the bromide ion concentration was constructed to achieve the visual detection of different concentrations of bromomethane.

[0068] The results show that, using the detection method of the present invention, as the concentration of bromomethane in the solution increases, the color change of the solution after the reaction is mainly purple-blue-green; the level of bromomethane in the solution can be determined based on the color change of the solution.

[0069] Example 2

[0070] A method for quantitative detection of bromomethane based on CsPbC13 quantum dots includes the following steps:

[0071] 1) Dilute 1.0 ml of bromomethane in 10 ml of cyclohexane, add 1 ml of oleylamine to the solution, mix well, and react under a UV lamp with an excitation wavelength of 365 nm and a power of 20 W for 60 s to allow the bromomethane to undergo a secondary nucleophilic substitution reaction (S0). N 2) The reaction produces free bromide ions, which are then diluted to obtain bromide ion solutions of different concentrations (0.667 ppb, 0.600 ppb, 0.500 ppb, 0.400 ppb, 0.333 ppb, 0.267 ppb, 0.200 ppb, 0.133 ppb).

[0072] 2) Mix 80 μL of bromide ion solutions of different concentrations with 50 μL of CsPbCl3 quantum dot dispersion, react at room temperature for 10 min, and then perform fluorescence spectroscopy under UV irradiation in the range of 400-600 nm. Measure the peak positions of the CsPbCl3 quantum dot fluorescence emission peaks before and after the introduction of bromomethane in three parallel measurements (selected within the range of 410-520 nm). Establish a linear relationship between the change in peak position and the bromide ion concentration (bromomethane concentrations of 0.667 ppb, 0.600 ppb, 0.500 ppb, 0.400 ppb, 0.333 ppb, 0.267 ppb, 0.200 ppb, and 0.133 ppb) to achieve quantitative testing of bromomethane content.

[0073] The results showed that the elution peak of the CsPbCl3 quantum dot solution was 410 nm without the addition of methyl bromo. The addition of methyl bromo or oleylamine alone did not cause a rightward shift in the elution peak position of the CsPbCl3 quantum dot fluorescence emission. However, when methyl bromo reacts with oleylamine to generate free bromide ions, the elution peak position of the CsPbCl3 quantum dot fluorescence emission shifts to the right. This is because a reaction occurs between the bromide ions and the CsPbCl3 quantum dots (e.g., ...). Figure 4 (As shown). After adding different concentrations of methyl bromo, the fluorescence emission peak positions of CsPbCl3 quantum dots ranged from 410-520 nm, and the change in peak position of CsPbCl3 quantum dots increased with increasing methyl bromo concentration. Figure 5 (a)) in different concentration ranges (0.333ppb-0.667ppb) Figure 5 (b) and 0.067ppb-0.400ppb Figure 5 (c) Both exhibit linear trends, with linear correlation coefficients of 0.997 and 0.992, respectively; enabling specific identification and quantification of bromomethane.

[0074] Example 3

[0075] A method for visually detecting bromomethane based on CsPbC13 quantum dots, specifically including the following steps:

[0076] 1) Dilute 1.0 ml of bromomethane in 10 ml of cyclohexane, add 1 ml of oleylamine to the solution, mix well, and react under a UV lamp with an excitation wavelength of 365 nm and a power of 20 W for 60 s to allow the bromomethane to undergo a secondary nucleophilic substitution reaction (S0). N 2) The reaction produces free bromide ions, which are then diluted to obtain bromide ion solutions of different concentrations (1 ppb, 0.667 ppb, 0.467 ppb, 0.333 ppb, 0.200 ppb, 0.067 ppb, 0.047 ppb, 0.033 ppb, 0.020 ppb, 0.007 ppb).

[0077] 2) Take 600 μL of bromide ion solutions of different concentrations and mix them with 375 μL of CsPbCl3 quantum dots in an EP tube. React at room temperature for 10 min. Observe the color change of the solution before and after the reaction under ultraviolet light. This will enable the preliminary visualization detection of different concentrations of bromomethane.

[0078] The results showed that the CsPbCl3 quantum dot solution was purple without the addition of methyl bromo, and the color of the CsPbCl3 quantum dot solution gradually changed from purple to blue to green after the addition of different concentrations of methyl bromo. Figure 5 (d) In this study, when the concentration of bromomethane is below 0.03 ppb, the solution is purple; when the concentration of bromomethane is between 0.03 and 0.2 ppb, the solution color changes from purple to blue; and when the concentration of bromomethane exceeds 0.3 ppb, the solution color turns green. Based on the rich fluorescence color changes in the solution, a visual semi-quantitative detection of bromomethane can be achieved.

[0079] Example 4

[0080] A rapid method for detecting bromomethane in tea leaves involves applying obtained CsPbCl3 quantum dots to detect bromomethane in a tea matrix, specifically including the following steps:

[0081] 1) Dilute 1.0 ml of bromomethane in 10 ml of a cyclohexane solution of tea leaves (tea leaves do not contain bromomethane). Add 3 ml of oleylamine to the solution, mix well, and react under a UV lamp with an excitation wavelength of 254 nm and a power of 20 W for 20 s to allow bromomethane to undergo a secondary nucleophilic substitution reaction (S0). N 2) The reaction produces free bromide ions, which are further diluted to concentrations of 0.13 ppb, 0.27 ppb, 0.33 ppb, 0.40 ppb, 0.47 ppb, and 0.67 ppb, respectively.

[0082] 2) Then, it was mixed with 50 μL of the obtained CsPbCl3 quantum dots and reacted at room temperature for 10 min. Then, fluorescence spectroscopy was performed in the range of 400-600 nm. The peak positions of the fluorescence emission peaks of the CsPbCl3 quantum dots before and after introducing bromomethane into the cyclohexane solution matrix of tea with different concentrations were measured. The change in the peak position was substituted into the linear equation obtained in Example 2 to calculate the predicted value of bromomethane concentration in the tea matrix by the model and to calculate its recovery rate. The results are shown in Table 1.

[0083] Table 1. Determination results of methyl bromide in tea matrix

[0084]

[0085] The results showed that the recovery rates of methyl bromide at six different concentrations (0.13 ppb, 0.27 ppb, 0.33 ppb, 0.40 ppb, 0.47 ppb, and 0.67 ppb) in the tea matrix remained between 94% and 103% (as shown in Table 1), enabling specific identification and quantification of methyl bromide in the tea matrix.

[0086] Comparative Example 1

[0087] A rapid method for detecting methyl bromide in tea is provided. The specific detection method is largely the same as that in Example 1, except that CdTe quantum dots, CdS quantum dots, ZnS quantum dots, and carbon quantum dots are used instead of the CsPbCl3 quantum dots described in this invention.

[0088] The results showed that after the reaction at room temperature (step 2), no color change or rightward shift of the fluorescence emission peak was observed due to different concentrations of methyl bromide under UV irradiation.

[0089] Comparative Example 2

[0090] A rapid method for detecting bromomethane in tea is provided. The specific detection method is largely the same as that in Example 1, except that the secondary nucleophilic substitution reaction in step 1) does not introduce ultraviolet light irradiation and the reaction time is extended to 10-20 min.

[0091] Although the above method can establish the relationship between the color change of the fluorescent solution and the concentration of bromide ions, it cannot efficiently and completely convert bromomethane into bromide ions, thus failing to achieve effective detection of the true bromomethane content. The detection results are significantly lower than the true bromomethane content.

[0092] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations; therefore, any obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. A method for rapid detection of bromomethane, characterized in that, The process includes the following steps: First, a nucleophilic reagent is added to a base solution containing bromomethane. Under ultraviolet irradiation, a secondary nucleophilic substitution reaction is carried out to generate free bromide ions. Then, CsPbCl3 quantum dots are introduced to carry out the reaction. The color change information of the resulting solution or the rightward shift information of the fluorescence peak position of the solution system at 410~520nm is obtained to achieve the visual detection of bromomethane. The nucleophile is an amine, thiol, or thiourea nucleophile; The ultraviolet irradiation conditions used ultraviolet lamps with a wavelength of 254~365 nm and a power of 15~30 W.

2. The method according to claim 1, characterized in that, The information regarding the rightward shift of the fluorescence emission peak position represents the change in peak position before and after the reaction.

3. The method according to claim 1, characterized in that, The molar ratio of the introduced bromomethane to the nucleophile is 1:1~2.

4. The method according to claim 1, characterized in that, The secondary nucleophilic substitution reaction was carried out at room temperature for 20–60 s.

5. The method according to claim 1, characterized in that, The preparation method of CsPbC13 quantum dots is as follows: (1) Weigh out Cs salt and mix with oleic acid, heat and dissolve to prepare Cs precursor solution; weigh out Pb salt, octadecene, 4-chlorobutyric acid and oleylamine, mix and heat to dissolve to prepare Pb precursor solution; (2) The Cs precursor solution was rapidly injected into the Pb precursor solution for reaction, and the reaction solution was rapidly cooled by an ice bath to obtain the crude product Cs4PbCl6 NPs. After washing, white Cs4PbCl6 NPs solid was obtained. (3) The obtained white Cs4PbCl6 NPs solid was dispersed in an organic solvent and water was rapidly injected under shaking conditions. After shaking treatment, standing treatment, centrifugation was performed to remove the bottom phase precipitate and obtain CsPbCl3 quantum dots.

6. The method according to claim 5, characterized in that, The heating and melting temperature is 150~200 ℃, and the time is 1~2 h.

7. The method according to claim 5, characterized in that, In the Pb precursor solution, the molar ratio of Pb salt, 4-chlorobutyric acid, and oleylamine is 1:55~65:115~125.

8. The method according to claim 1, characterized in that, The reaction time after introducing CsPbCl3 quantum dots is 5~15 min.

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