Perovskite-based nano material and preparation method and application thereof

Abstract

The invention belongs to the technical field of chloride detection, and particularly relates to a perovskite-based nano material and a preparation method and application thereof. The perovskite-based nano material comprises an up-conversion nano material and Ag2S quantum dots, and the up-conversion nano material is connected with the Ag2S quantum dots through chemical bonds; the up-conversion nano material has a core-shell structure, a Yb < 3 + > / Er < 3 + > doped Cs2NaYF6 nano particle is used as an inner core, and the outer part of the inner core is coated with a Cs2NaYF6 shell. Adding the perovskite-based nano material into a to-be-tested sample, testing the emission intensity of the to-be-tested sample at 300-750 nm under the excitation of 980 nm laser, and calculating the concentration of chloride according to the standard curve. The perovskite-based nano material prepared by the invention has the characteristics of high detection accuracy and the like in chloride detection, can realize quantitative detection of micromole-magnitude chloride, and is simple in preparation method and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of chloride detection technology, specifically relating to a perovskite-based nanomaterial, its preparation method, and its application. Background Technology

[0002] Chlorides are compounds containing chlorine, including inorganic chlorides such as sodium chloride and potassium chloride, as well as various organic chlorides. These substances are mostly soluble in water and often exist in crystalline or liquid form, widely distributed in drinking water, food processing, industrial wastewater, and soil. However, excessive chlorides pose a significant threat to human health and the ecological environment: for humans, long-term intake of high concentrations of chlorides may cause elevated blood pressure and increased kidney burden; some organic chlorides are also toxic and even carcinogenic. For the ecological environment, excessive chlorides can disrupt the ion balance of water bodies, harming the survival of aquatic organisms; simultaneously, chlorides in industrial wastewater can accelerate equipment corrosion and lead to soil pollution. Therefore, achieving efficient detection and control of chlorides is of great significance.

[0003] Currently, conventional methods for chloride detection mainly include chemical analysis, electrochemical sensor methods, and chromatography. Chemical analysis methods are typically cumbersome and time-consuming; electrochemical sensor methods suffer from insufficient stability and high maintenance costs; while chromatography offers good sensitivity, the instruments are expensive and the analysis speed is slow, making it unsuitable for rapid on-site detection. Furthermore, existing detection methods still face challenges such as insufficient sensitivity and limited selectivity in detecting trace amounts of chloride (e.g., at the microgram level), making it difficult to meet the increasingly stringent requirements for environmental monitoring and health protection. Summary of the Invention

[0004] The purpose of this invention is to provide a perovskite-based nanomaterial, its preparation method, and its application, thereby overcoming the shortcomings of the prior art. The prepared perovskite-based nanomaterial has the characteristics of high detection accuracy in chloride detection, and can realize the quantitative detection of chloride at the micromolar level. Moreover, the preparation method is simple and low in cost.

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

[0006] In a first aspect, the present invention provides a perovskite-based nanomaterial comprising an upconversion nanomaterial and an Ag2S quantum dot, wherein the upconversion nanomaterial and the Ag2S quantum dot are connected by a chemical bond; specifically, the metal ions in the upconversion nanomaterial are combined with the sulfur ions in the Ag2S quantum dot.

[0007] Upconversion nanomaterials (chemical formula Cs2NaYF6:Yb) 3+ / Er 3+ @Cs2NaYF6) has a core-shell structure, with Yb 3+ / Er 3+The core consists of doped Cs2NaYF6 nanoparticles, which are coated with a Cs2NaYF6 shell.

[0008] This invention utilizes core-shell structured upconversion nanomaterials (Cs2NaYF6:Yb). 3+ / Er 3+ The core-shell structure (Cs2NaYF6) is chemically bonded to Ag2S quantum dots, achieving multifaceted performance optimization and functional integration. First, the inert Cs2NaYF6 shell effectively passivates surface defects in the core, significantly improving upconversion luminescence efficiency. Furthermore, the chemical bonding interface with Ag2S quantum dots enables efficient energy transfer, resulting in synergistic quenching optical properties. Second, the core-shell structure and chemical bonding together enhance the material's physical and chemical stability. This structure combines high-efficiency upconversion luminescence, near-infrared response, and photothermal conversion, creating an ideal nanoplatform for highly sensitive specific sensing (such as chloride detection), multimodal bioimaging, and even integrated diagnostic and therapeutic applications.

[0009] In some other embodiments, the mass ratio of upconversion nanomaterial to Ag2S quantum dots is (1.3~1.51):1; the particle size of the upconversion nanomaterial is 10~20 nm; and the particle size of the Ag2S quantum dots is 4~6 nm.

[0010] Specifically, the upconversion nanomaterial Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 is hexagonal plate-like with an average particle size of 15 nm; Ag2S quantum dots are dot-like with an average particle size of 4 nm; Cs2NaYF6:Yb 3+ / Er 3+ The @Cs2NaYF6-Ag2S nanoparticles are hexagonal plate-like with dotted structures, with an average particle size of 15 nm.

[0011] In some other embodiments, Yb in the core of the upconversion nanomaterial 3+ The molar concentration of doping is 12-15%; Er 3+ The molar concentration of doping is 1~1.5%; preferably Yb. 3+ The molar concentration of doping is 15%; Er 3+ The molar concentration of the dopant is 1%.

[0012] The thickness of the shell of the upconversion nanomaterial is 3~7nm; The surface of perovskite-based nanomaterials is further modified with amino groups, which are obtained by reacting polyethyleneimine with perovskite-based nanomaterials. Amino groups effectively passivate coordination defects on the material surface and suppress non-radiative recombination, thereby significantly improving their photoluminescence quantum yield and fluorescence stability. Simultaneously, amino groups can enhance crystal structure stability through coordination and block water and oxygen erosion, improving the material's environmental tolerance. Furthermore, as active functional groups, amino groups provide anchor sites for further covalent modification, facilitating directional coupling with biomolecules, polymers, or other functional materials, greatly expanding their application potential in fields such as biosensing, targeted imaging, and optoelectronic composite devices.

[0013] In a second aspect, the present invention provides a method for preparing the perovskite-based nanomaterials of the first aspect, comprising the following steps: (1) Under an inert atmosphere, ytterbium salt, yttrium salt, erbium salt, sodium salt, oleic acid, 1-octadecene and oleylamine were mixed and heated to react. Then, the mixture was mixed with an alcoholic solution of CsF, and after heating to remove the alcoholic solution, a co-precipitation reaction was carried out to purify and obtain Yb. 3+ / Er 3 + Doped Cs2NaYF6 nanoparticles were dispersed in an organic solvent for later use. (2) Under an inert atmosphere, yttrium salt, sodium salt, oleic acid, 1-octadecene and oleylamine are mixed and heated to react, and Yb is added. 3+ / Er 3+ A solution of doped Cs2NaYF6 nanoparticles and an alcoholic solution of CsF were subjected to a co-precipitation reaction after the alcoholic solution was removed by heating. The resulting upconversion nanomaterials were purified and dispersed in an organic solvent for later use. (3) The upconversion nanomaterial solution was mixed with oleic acid, 1-octadecene, dodecyl mercaptan and silver diethyldithiocarbamate, and heated to obtain a reaction solution; then a coprecipitation reaction was carried out to purify the perovskite-based nanomaterial, which was then dispersed in an organic solvent for later use. (4) Add tetrafluoroborate nitrite to a mixed solution of DMF and cyclohexane and stir to mix. Add perovskite-based nanomaterial solution to react. After centrifugation, disperse the solid with DMF and add it to an alcohol-water solution of polyethyleneimine to mix and react. After purification, the product is obtained.

[0014] In some other embodiments, in step (1), the molar ratio of ytterbium salt, yttrium salt, erbium salt and sodium salt is (1.48~1.52): 1: (8.2~8.6): (9.8~10.2); in step (2), the molar ratio of yttrium salt and sodium salt is 1: (0.98~1.02).

[0015] In some other embodiments, in step (1) or step (2), the ytterbium salt includes Yb(Ac)3, the erbium salt includes Er(Ac)3, the yttrium salt includes Y(Ac)3, and the sodium salt includes NaAc·3H2O; the volume ratio of oleic acid, oleylamine and 1-octadecene is (198~202): (98~102): (198~202); the temperature of the heating reaction is 120~130℃, the molar ratio of CsF to sodium salt is (9.8~10.2):1; the temperature of the coprecipitation reaction is 290~330℃, and the time is 1~2 h.

[0016] In some other embodiments, in step (3), the ratio of the upconversion nanomaterial to oleic acid and 1-octadecene is 1 mmol:(3.8~4.2) mL:(9.8~10.2) mL; The heating reaction temperature is 65~75 ℃, and the time is 30~40 min; The ratio of silver diethyldithiocarbamate to n-dodecyl mercaptan was 1 mmol:(468~472) mL; the coprecipitation reaction was carried out at a temperature of 120~130℃ for 10~15 min.

[0017] In some other embodiments, in step (4), the mass ratio of polyethyleneimine to perovskite-based nanomaterials is (2.5~3):1.

[0018] Thirdly, the present invention provides the application of the perovskite-based nanomaterials of the first aspect in chloride detection.

[0019] In some other embodiments, the chloride detection method is as follows: perovskite-based nanomaterials are added to the sample to be tested, and the emission intensity of the sample to be tested is measured in the range of 300~750 nm under 980 nm laser excitation. The concentration of chloride is calculated according to the standard curve.

[0020] Specifically, the chloride detection method is as follows: perovskite-based nanomaterials are mixed with the chloride solution to be tested; a laser source with a wavelength of 980 nm is used as the excitation light to detect the emission spectrum, and the concentration of chloride in the chloride solution to be tested is obtained based on the emission spectrum of the chloride solution to be tested and the standard curve; The standard curve was constructed as follows: standard chloride solutions of different concentrations were mixed with perovskite-based nanomaterials, and the emission spectra of the different mixtures were excited and detected. The standard curve of luminescence intensity versus chloride concentration was obtained based on the emission spectra.

[0021] The beneficial effects of this invention are: (1) The perovskite-based nanomaterials provided have strong fluorescence emission and small particle size. Their synthesis process is simple and low cost, which is conducive to simplifying the industrial detection process and reducing the application cost.

[0022] (2) This material can achieve specific quantitative detection of chlorides through excitation luminescence, with the advantages of wide measurement range and high accuracy, and can achieve accurate measurement within a certain concentration range. After interacting with chloride solutions of different concentrations, its emission spectrum peak changes linearly with the increase of chloride concentration, thereby realizing quantitative detection of chlorides. This change originates from the interaction between Ag2S quantum dots on the material surface and chlorides. This interaction modulates the luminescence intensity of the quantum dots and weakens their quenching effect on perovskite luminescence, which not only improves the detection sensitivity but also realizes the visualization of chloride detection, and has good prospects for practical application.

[0023] (3) When the material reacts with a variety of common ions and compounds (such as zinc, aluminum, copper, iodine, chloride, fluorine, ammonium, phosphate, etc.), it only shows a significant fluorescence enhancement response to chloride, which proves that it has excellent detection specificity. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Transmission electron microscopy image of @Cs2NaYF6 nanoparticles, scale bar 100 nm; Figure 2 This is a transmission electron microscope image of Ag2S quantum dots in Example 1 of the present invention, with a scale bar of 50 nm; Figure 3 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Transmission electron microscopy image of @Cs2NaYF6-Ag2S nanoparticles, scale bar 50 nm; Figure 4 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Cs2NaYF6: Yb 3+ / Er 3+ X-ray diffraction pattern of @Cs2NaYF6 nanoparticles; Figure 5 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6、Cs2NaYF6:Yb3+ / Er 3+ Emission spectrum of @Cs2NaYF6-Ag2S nanoparticles under 980nm excitation; Figure 6 The emission spectrum of the Ag2S quantum dot in Example 1 of this invention; Figure 7 This is the absorption intensity spectrum of the Ag2S quantum dots in Example 1 of the present invention; Figure 8 This is a graph showing the absorption intensity relationship of Ag2S quantum dots in Example 1 of the present invention; Figure 9 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Emission spectrum of Cs2NaYF6-Ag2S-PEI nanoparticles; Figure 10 Cs2NaYF6:Yb in Embodiment 1 of the present invention 3+ / Er 3+ Fourier transform infrared absorption spectrum of @Cs2NaYF6-Ag2S quantum dot nanoparticles; Figure 11 This is a graph showing the relationship between chloride concentration and emission intensity of perovskite-based nanomaterials in Example 2 of the present invention. Figure 12 Cs2NaYF6:Yb in Embodiment 3 of the present invention 3+ / Er 3+ @Cs2NaYF6-Ag2S-PEI specific detection diagram for chlorides. Detailed Implementation

[0026] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.

[0027] Example 1 This embodiment provides a method for preparing perovskite-based nanomaterials, specifically including the following steps: Step 1. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of nanoparticles is as follows: (1) Add NaAc·3H2O (0.5 mmol), Y(Ac)3 (0.42 mmol, 84%), Yb(Ac)3 (0.075 mmol, 15%) and Er(Ac)3 (0.005 mmol, 1%) to a three-necked flask containing a high-temperature magnetic stir bar, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to room temperature.

[0028] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution and add it to the light yellow transparent solution in step (1) to make a mixed solution. Heat the mixed solution to 70 °C and keep it for 30 min, then remove the methanol.

[0029] (3) In a sealed three-necked flask, the mixed solution after removing methanol was evacuated and kept under vacuum for 15 min, then heated to 320°C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0030] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Yb. 3+ / Er 3+ Co-doped Cs₂NaYF nanoparticles, labeled Cs₂NaYF₆:Yb 3+ / Er 3+ Nanoparticles were prepared and dispersed in 10 mL of cyclohexane for later use.

[0031] Step 2. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of @Cs2NaYF6 nanoparticles is as follows: (1) Add NaAc·3H2O (0.50 mmol) and Y(Ac)3 (0.50 mmol, 100%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to 70 °C.

[0032] (2) Yb 3+ / Er 3+ Co-doped Cs2NaYF nanoparticles (Cs2NaYF6:Yb) 3+ / Er 3+ Add the cyclohexane solution dropwise into the light yellow transparent solution in step (1) to form a mixed solution. Heat the mixed solution to 70 °C and maintain it for 30 min.

[0033] (3) Dissolve 5 mmol of CsF in 8 mL of methanol solution, add it to the mixed solution in step (2), heat to 70°C and keep for 30 min, and remove methanol.

[0034] (4) In a sealed three-necked flask, the solution after removing methanol in step (3) was evacuated and kept under vacuum for 15 min, then heated to 330 °C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0035] (5) Add excess ethanol (40 mL) to the crude product obtained in step (4), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0036] Step 3. The preparation method of Ag2S quantum dots is as follows: (1) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to a three-necked flask containing a high-temperature magnet. In the sealed three-necked flask, the above solution is evacuated and kept for 10 min. Then, it is heated to 125 °C under nitrogen protection and kept for 10 min. After that, it is naturally cooled to room temperature to obtain the crude product.

[0037] (2) Add excess ethanol (40 mL) to the crude product obtained in step (1), centrifuge at 10000 r / min for 10 min to obtain Ag2S quantum dots, and disperse them in 10 mL of cyclohexane for later use.

[0038] Step 4. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of @Cs2NaYF6-Ag2S nanoparticles is as follows: (1) Add 2 ml of oleic acid and 5 ml of octadecene to a three-necked flask containing a high-temperature magnetic flask, and add Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticle solution was added dropwise to the above solution to prepare a mixed solution. The mixed solution was heated to 70 °C and held for 40 min.

[0039] (2) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to the mixed solution in step (1). In a sealed three-necked flask, evacuate the solution for 10 min and heat it to 125°C under nitrogen protection for 10 min. Then, allow it to cool naturally to room temperature to obtain the crude product.

[0040] (3) Add excess ethanol (40 mL) to the crude product obtained in step (2), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @ Cs2NaYF6-Ag2S nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0041] Step 5. Cs2NaYF6:Yb 3+ / Er 3+ The surface modification method for Cs2NaYF6-Ag2S is as follows: Weigh 200 mg of nitrite tetrafluoroborate solid and add it to a mixed solution containing 10 mL of DMF and 6 mL of cyclohexane. Stir for 15 min. Add 10 mL of a perovskite-based nanoparticle solution dispersed in cyclohexane (prepared in step 3 as Cs2NaYF6:Yb). 3+ / Er 3 + @ Cs2NaYF6-Ag2S nanoparticles), stirred for 30 min. The reacted solution was centrifuged (12000 r / min × 10 min) and dispersed with 5 mL DMF. A mixed solution of water (20 mL) and ethanol (10 mL) containing 100 mg polyethyleneimine (PEI) was added to the DMF solution of the perovskite-based nanoparticles, stirred overnight, washed with water, and dispersed in 20 mL of water to obtain Cs2NaYF6:Yb 3+ / Er 3+ @ Cs2NaYF6-Ag2S-PEI.

[0042] like Figure 1 The transmission electron microscopy (TEM) images show that the Cs2NaYF6:Yb prepared in this embodiment... 3+ / Er 3+ The Cs2NaYF6 nanoparticles are hexagonal sheets with a size of 15 nm; Figure 2 As shown in the transmission electron microscopy (TEM) images, the Ag₂S quantum dots prepared in this embodiment exhibit a dot-like shape with a size of 4 nm; Figure 3 As shown in the transmission electron microscopy (TEM) images, the Cs2NaYF6:Yb prepared in this embodiment exhibits [significantly positive results]. 3+ / Er 3+ @Cs2NaYF6-Ag2S nanoparticles exhibit a hexagonal sheet-like structure with dots, and a size of 15 nm.

[0043] like Figure 4 As shown, Cs2NaYF6:Yb prepared in Example 1 3+ / Er 3+Completely identical to the standard card (PDF#20-1214), Cs2NaYF6:Yb 3+ / Er 3+ The Cs2NaYF6 nanoparticles are completely identical to the standard card (PDF#20-1214), indicating that the prepared Cs2NaYF6:Yb nanoparticles are of high quality. 3+ / Er 3+ Cs2NaYF6:Yb 3+ / Er 3+ The Cs2NaYF6 nanoparticles are all pure phase structures.

[0044] like Figure 5 As shown in the emission spectrum results, the Cs2NaYF6:Yb prepared with an excitation source of 980 nm and a power of 1.2 W was tested. 3+ / Er 3+ Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6、Cs2NaYF6:Yb 3+ / Er 3+ The emission peaks of Cs2NaYF6-Ag2S nanoparticles are at 550 nm and 660 nm; Cs2NaYF6:Yb 3+ / Er 3+ The luminescence intensity of @Cs2NaYF6-Ag2S at 550 nm is significantly lower than that of Cs2NaYF6:Yb. 3+ / Er 3+ @Cs2NaYF6.

[0045] like Figure 6 As shown in the emission spectrum results, the emission peaks of Ag₂S quantum dots prepared with an excitation source of 980 nm and a power of 1.2 W are at 1080 nm and 1250 nm. Figure 7 The image shows the absorption intensity spectrum of Ag2S quantum dots. Figure 8 The figure shows the absorption intensity relationship of Ag₂S quantum dots in the concentration range of 0.0024~0.04 mmol / L according to the present invention. The fitted linear equation is y=55.3719x+0.1114, and the goodness of fit R₂ is 0.0024~0.04 mmol / L. 2 =0.9966, indicating that the regression line fits the detection value well; like Figure 9 As shown, it is Cs2NaYF6:Yb 3+ / Er 3+ Emission spectra of Cs2NaYF6-Ag2S-PEI nanoparticles prepared with an excitation source of 980 nm and a power of 1.2 W. 3+ / Er 3+The emission peaks of the @Cs2NaYF6-Ag2S-PEI nanoparticles are at 550 nm and 660 nm, respectively.

[0046] like Figure 10 As shown, the Cs2NaYF6:Yb used in this embodiment 3+ / Er 3+ Fourier transform infrared absorption spectrum of @Cs2NaYF6-Ag2S nanoparticles: at 1723 cm⁻¹ -1 The absorption peak at 2857 cm⁻¹ corresponds to the stretching vibration of the C=O bond in the carboxyl group -COOH. -1 The absorption peak at that point corresponds to S 2- Stretching vibration of Au-S bond in the middle.

[0047] Example 2 This embodiment provides a method for detecting chloride concentration using perovskite-based nanomaterials, specifically including the following steps: (1) Prepare chloride solutions of different concentrations. Take 0.20 mL of each concentration and add it to a 1.5 mL centrifuge tube. Add 0.20 mL of the material prepared in Example 1 above to each centrifuge tube and react for 4 h.

[0048] (2) Under 980 nm laser excitation, the emission intensity (300~750 nm) of the solution in all centrifuge tubes was tested, and the linear relationship between chloride concentration and emission intensity of perovskite-based nanomaterials was obtained.

[0049] (3) Randomly take 0.1 mL of industrial wastewater, add perovskite-based nanomaterials and react for 4 h, and calculate the chloride concentration in the industrial wastewater by emission intensity.

[0050] like Figure 11 The figure shows the relationship between the emission intensity of chloride and perovskite-based nanomaterials in the concentration range of 50-500 mmol / L according to this invention. The fitted linear equation is y=3.31x+1471.41, and the goodness of fit R is 1 / 2. 2 =0.9768, indicating that the regression line fits the detection value well.

[0051] Example 3 Specificity detection of the composite nanomaterials prepared in Example 1: (1) Prepare solutions of zinc nitrate hexahydrate, aluminum nitrate, anhydrous copper sulfate, potassium iodide, sodium hypochlorite, sodium fluoride, ammonium fluoride, ammonium nitrate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, water, and sodium chloride with the same concentration (500 mmol / L). Take 0.20 mL of each solution and add it to a 1.5 mL centrifuge tube. Add 0.20 mL of the material prepared in Example 1 to each centrifuge tube and react for 4 h.

[0052] (2) Under 980 nm laser excitation, the fluorescence intensity (350~750 nm) of the solution in all centrifuge tubes was tested to achieve specific detection of chloride (judged by the difference between the initial emission intensity value of the composite material and the initial emission intensity value of the composite material; the larger the difference, the stronger the specificity). The specific data are shown in Table 1.

[0053] Among them, Cs2NaYF6:Yb prepared in Example 1 3+ / Er 3+ The initial emission intensity of the @Cs2NaYF6-Ag2S-PEI nanomaterial is 5459.

[0054] Table 1 shows the specific detection results for chloride. Different ions emission intensity difference Zinc nitrate hexahydrate -4031 Aluminum nitrate -4643 Anhydrous copper sulfate -4724 Potassium iodide -4066 Sodium hypochlorite -4444 Sodium fluoride -4017 ammonium fluoride -4146 ammonium nitrate -4265 Potassium dihydrogen phosphate -4111 Sodium dihydrogen phosphate -4178 Ammonium dihydrogen phosphate -4115 Sodium chloride 7986 From Table 1 and Figure 12 As shown, the results indicate that Cs2NaYF6:Yb 3+ / Er 3+ The luminescence intensity of the @Cs2NaYF6-Ag2S-PEI nanomaterial increases when it reacts only with chlorides.

[0055] Comparative Example 1 Unlike Example 1, step 1 involves preparing single-ion-doped Cs₂NaYF₆ nanoparticles, namely Cs₂NaYF₆:Yb. 3+ Nanoparticles or Cs2NaYF6:Er 3+ Nanoparticles. Specifically, Cs2NaYF6:Yb were prepared. 3+ When nanoparticles are used, Er 3+ Equivalent replacement with Yb 3+ Other preparation steps remain unchanged. Preparation of Cs₂NaYF₆:Er 3+ When using nanoparticles, Yb 3+ Equivalent replacement with Er 3+ Other preparation steps remain unchanged.

[0056] Specifically, Cs2NaYF6:Yb 3+ The preparation method of nanoparticles is as follows: (1) Add NaAc·3H2O (0.5 mmol), Y(Ac)3 (0.42 mmol, 84%), and Yb(Ac)3 (0.08 mmol, 16%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to room temperature.

[0057] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution and add it to the light yellow transparent solution in step (1) to make a mixed solution. Heat the mixed solution to 70 °C and keep it for 30 min, then remove the methanol.

[0058] (3) In a sealed three-necked flask, the mixed solution after removing methanol was evacuated and kept under vacuum for 15 min, then heated to 320°C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0059] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Yb. 3+ Co-doped Cs₂NaYF nanoparticles, labeled Cs₂NaYF₆:Yb 3+ Nanoparticles were prepared and dispersed in 10 mL of cyclohexane for later use.

[0060] Cs2NaYF6:Er 3+ The preparation method of nanoparticles is as follows: (1) Add NaAc·3H2O (0.5 mmol), Y(Ac)3 (0.42 mmol, 84%), and Er(Ac)3 (0.08 mmol, 16%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to room temperature.

[0061] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution and add it to the light yellow transparent solution in step (1) to make a mixed solution. Heat the mixed solution to 70 °C and keep it for 30 min, then remove the methanol.

[0062] (3) In a sealed three-necked flask, the mixed solution after removing methanol was evacuated and kept under vacuum for 15 min, then heated to 320°C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0063] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Er. 3+ Co-doped Cs₂NaYF nanoparticles, labeled Cs₂NaYF₆:Er 3+ Nanoparticles were prepared and dispersed in 10 mL of cyclohexane for later use.

[0064] Comparative Example 2 Unlike Example 1, preparation step 1, Cs2NaYF6:Yb, was omitted.3+ / Er 3+ In the preparation of nanoparticles, the addition of Cs2NaYF6:Yb is omitted in step 2. 3+ / Er 3+ The preparation steps for the nanoparticles are the same as in Example 1. The specific procedures are as follows: Step 1. The preparation method of Cs2NaYF6 nanoparticles is as follows: (1) Add NaAc·3H2O (0.50 mmol) and Y(Ac)3 (0.50 mmol, 100%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to 70 °C.

[0065] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution, add it to the mixed solution in step (1), heat to 70°C and keep for 30 min, and remove methanol.

[0066] (3) In a sealed three-necked flask, the solution after removing methanol in step (2) was evacuated and kept under vacuum for 15 min, then heated to 330 °C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0067] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0068] Step 2. The preparation method of Ag2S quantum dots is as follows: (1) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to a three-necked flask containing a high-temperature magnet. In the sealed three-necked flask, the above solution is evacuated and kept for 10 min. Then, it is heated to 125 °C under nitrogen protection and kept for 10 min. After that, it is naturally cooled to room temperature to obtain the crude product.

[0069] (2) Add excess ethanol (40 mL) to the crude product obtained in step (1), centrifuge at 10000 r / min for 10 min to obtain Ag2S quantum dots, and disperse them in 10 mL of cyclohexane for later use.

[0070] Step 3. The preparation method of Cs2NaYF6-Ag2S nanoparticles is as follows: (1) Add 2 ml of oleic acid and 5 ml of octadecene to a three-necked flask containing a high-temperature magnet, and add Cs2NaYF6 nanoparticle solution to the above solution to make a mixed solution. Heat the mixed solution to 70 °C and maintain it for 40 min.

[0071] (2) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to the mixed solution in step (1). In a sealed three-necked flask, evacuate the solution for 10 min and heat it to 125°C under nitrogen protection for 10 min. Then, allow it to cool naturally to room temperature to obtain the crude product.

[0072] (3) Add excess ethanol (40 mL) to the crude product obtained in step (2), centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6-Ag2S nanoparticles, and disperse them in 10 mL of cyclohexane for later use.

[0073] Step 4. The surface modification method for Cs2NaYF6-Ag2S is as follows: Weigh 200 mg of nitrosotetrafluoroborate solid and add it to a mixed solution containing 10 mL of DMF and 6 mL of cyclohexane. Stir for 15 min. Add 10 mL of a perovskite-based nanoparticle solution dispersed in cyclohexane (Cs2NaYF6-Ag2S nanoparticles prepared in step 3) and stir for 30 min. Centrifuge the reacted solution (12000 r / min × 10 min) and disperse with 5 mL of DMF. Add a mixed solution of water (20 mL) and ethanol (10 mL) containing 100 mg of polyethyleneimine (PEI) to the DMF solution of the perovskite-based nanoparticles, stir overnight, wash with water, and disperse with 20 mL of water to obtain Cs2NaYF6-Ag2S-PEI.

[0074] Comparative Example 3 Unlike Example 1, preparation step 4, Cs2NaYF6:Yb, was omitted. 3+ / Er 3+ @Cs2NaYF6-Ag2S nanoparticles, directly on Cs2NaYF6:Yb in step 5 3+ / Er 3+ @Cs2NaYF6 was modified with polyethyleneimine (PEI), and other preparation steps were the same as in Example 1. The specific procedures are as follows: Step 1. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of nanoparticles is as follows: (1) Add NaAc·3H2O (0.5 mmol), Y(Ac)3 (0.42 mmol, 84%), Yb(Ac)3 (0.075 mmol, 15%) and Er(Ac)3 (0.005 mmol, 1%) to a three-necked flask containing a high-temperature magnetic stir bar, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to room temperature.

[0075] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution and add it to the light yellow transparent solution in step (1) to make a mixed solution. Heat the mixed solution to 70 °C and keep it for 30 min, then remove the methanol.

[0076] (3) In a sealed three-necked flask, the mixed solution after removing methanol was evacuated and kept under vacuum for 15 min, then heated to 320°C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0077] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Yb. 3+ / Er 3+ Co-doped Cs₂NaYF nanoparticles, labeled Cs₂NaYF₆:Yb 3+ / Er 3+ Nanoparticles were prepared and dispersed in 10 mL of cyclohexane for later use.

[0078] Step 2. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of @Cs2NaYF6 nanoparticles is as follows: (1) Add NaAc·3H2O (0.50 mmol) and Y(Ac)3 (0.50 mmol, 100%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to 70 °C.

[0079] (2) Yb 3+ / Er 3+ Co-doped Cs2NaYF nanoparticles (Cs2NaYF6:Yb) 3+ / Er 3+ Add the cyclohexane solution dropwise into the light yellow transparent solution in step (1) to form a mixed solution. Heat the mixed solution to 70 °C and maintain it for 30 min.

[0080] (3) Dissolve 5 mmol of CsF in 8 mL of methanol solution, add it to the mixed solution in step (2), heat to 70°C and keep for 30 min, and remove methanol.

[0081] (4) In a sealed three-necked flask, the solution after removing methanol in step (3) was evacuated and kept under vacuum for 15 min, then heated to 330 °C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0082] (5) Add excess ethanol (40 mL) to the crude product obtained in step (4), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0083] Step 3. Cs2NaYF6:Yb 3+ / Er 3+ The surface modification method for Cs2NaYF6 is as follows: Weigh 200 mg of nitrite tetrafluoroborate solid and add it to a mixed solution containing 10 mL of DMF and 6 mL of cyclohexane. Stir for 15 min. Add 10 mL of a perovskite-based nanoparticle solution dispersed in cyclohexane (prepared in step 3 as Cs2NaYF6:Yb). 3+ / Er 3 + @ Cs2NaYF6 nanoparticles), stirred for 30 min. The reacted solution was centrifuged (12000 r / min × 10 min) and dispersed in 5 mL DMF. A mixed solution of water (20 mL) and ethanol (10 mL) containing 100 mg polyethyleneimine (PEI) was added to the DMF solution of the perovskite-based nanoparticles, stirred overnight, washed with water, and then dispersed in 20 mL of water to obtain Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6-PEI.

[0084] Comparative Example 4 Unlike Example 1, step 5 is omitted; the other preparation steps are the same as in Example 1. The specific operation is as follows: Step 1. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of nanoparticles is as follows: (1) Add NaAc·3H2O (0.5 mmol), Y(Ac)3 (0.42 mmol, 84%), Yb(Ac)3 (0.075 mmol, 15%) and Er(Ac)3 (0.005 mmol, 1%) to a three-necked flask containing a high-temperature magnetic stir bar, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to room temperature.

[0085] (2) Dissolve 5 mmol of CsF in 8 mL of methanol solution and add it to the light yellow transparent solution in step (1) to make a mixed solution. Heat the mixed solution to 70 °C and keep it for 30 min, then remove the methanol.

[0086] (3) In a sealed three-necked flask, the mixed solution after removing methanol was evacuated and kept under vacuum for 15 min, then heated to 320°C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0087] (4) Add excess ethanol (40 mL) to the crude product obtained in step (3), and centrifuge at 10000 r / min for 10 min to obtain Yb. 3+ / Er 3+ Co-doped Cs₂NaYF nanoparticles, labeled Cs₂NaYF₆:Yb 3+ / Er 3+ Nanoparticles were prepared and dispersed in 10 mL of cyclohexane for later use.

[0088] Step 2. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of @Cs2NaYF6 nanoparticles is as follows: (1) Add NaAc·3H2O (0.50 mmol) and Y(Ac)3 (0.50 mmol, 100%) to a three-necked flask containing a high-temperature magnetic ball, stir for 30 min to evaporate the water, then add 10 mL of oleic acid, 5 mL of oleylamine and 10 mL of octadecene, heat to 120 °C until a light yellow transparent solution is formed, and then cool naturally to 70 °C.

[0089] (2) Yb 3+ / Er 3+ Co-doped Cs2NaYF nanoparticles (Cs2NaYF6:Yb) 3+ / Er 3+ Add the cyclohexane solution dropwise into the light yellow transparent solution in step (1) to form a mixed solution. Heat the mixed solution to 70 °C and maintain it for 30 min.

[0090] (3) Dissolve 5 mmol of CsF in 8 mL of methanol solution, add it to the mixed solution in step (2), heat to 70°C and keep for 30 min, and remove methanol.

[0091] (4) In a sealed three-necked flask, the solution after removing methanol in step (3) was evacuated and kept under vacuum for 15 min, then heated to 330 °C under nitrogen protection and kept for 1 h, and then naturally cooled to room temperature to obtain the crude product.

[0092] (5) Add excess ethanol (40 mL) to the crude product obtained in step (4), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0093] Step 3. The preparation method of Ag2S quantum dots is as follows: (2) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to a three-necked flask containing a high-temperature magnet. In the sealed three-necked flask, the above solution is evacuated and kept for 10 min. Then, it is heated to 125 °C under nitrogen protection and kept for 10 min. After that, it is naturally cooled to room temperature to obtain the crude product.

[0094] (2) Add excess ethanol (40 mL) to the crude product obtained in step (1), centrifuge at 10000 r / min for 10 min to obtain Ag2S quantum dots, and disperse them in 10 mL of cyclohexane for later use.

[0095] Step 4. Cs2NaYF6:Yb 3+ / Er 3+ The preparation method of @Cs2NaYF6-Ag2S nanoparticles is as follows: (1) Add 2 ml of oleic acid and 5 ml of octadecene to a three-necked flask containing a high-temperature magnetic flask, and add Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 nanoparticle solution was added dropwise to the above solution to prepare a mixed solution. The mixed solution was heated to 70 °C and held for 40 min.

[0096] (2) Add 12 ml of dodecanethiol and 25.6 mg of silver diethyldithiocarbamate to the mixed solution in step (1). In a sealed three-necked flask, evacuate the solution for 10 min and heat it to 125°C under nitrogen protection for 10 min. Then, allow it to cool naturally to room temperature to obtain the crude product.

[0097] (3) Add excess ethanol (40 mL) to the crude product obtained in step (2), and centrifuge at 10000 r / min for 10 min to obtain Cs2NaYF6:Yb 3+ / Er 3+ @ Cs2NaYF6-Ag2S nanoparticles were dispersed in 10 mL of cyclohexane for later use.

[0098] The study found that, compared with Example 1, Comparative Example 1 prepared single-ion doped Cs2NaYF6 nanoparticles, namely Cs2NaYF6:Yb 3+ Nanoparticles or Cs2NaYF6:Er 3+ Nanoparticles do not emit light under 980 nm laser excitation and therefore cannot be used to detect chlorides. Comparative Example 2, compared to Example 1, omits Cs2NaYF6:Yb. 3+ / Er 3+ The nanoparticles, which only have a shell structure, do not emit light when excited by a 980 nm laser, making it impossible to detect chlorides.

[0099] Compared to Example 1, Comparative Example 3 omitted the preparation of Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6-Ag2S nanoparticles were directly processed using Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6 is modified with polyethyleneimine (PEI), lacking Ag. + The detection of chloride aims to detect Ag + With Cl in chloride - The reaction produces AgCl, which weakens the optical properties of Ag₂S quenching. Comparative Example 3 lacks Ag. + Therefore, chloride cannot be detected. Comparative Example 4, compared to Example 1, omits Cs2NaYF6:Yb. 3+ / Er 3+ @Cs2NaYF6-Ag2S modified with polyethyleneimine (PEI), Cs2NaYF6:Yb 3+ / Er 3+ @Cs2NaYF6-Ag2S is insoluble in water without polyethyleneimine (PEI) modification and can only be dispersed in cyclohexane, making it unsuitable for detecting chlorides dissolved in water.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A perovskite-based nanomaterial, characterized in that, It includes upconversion nanomaterials and Ag2S quantum dots, wherein the upconversion nanomaterials and Ag2S quantum dots are connected by chemical bonds; The upconversion nanomaterial has a core-shell structure, with Yb 3+ / Er 3+ The core consists of doped Cs2NaYF6 nanoparticles, which are coated with a Cs2NaYF6 shell.

2. The perovskite-based nanomaterial according to claim 1, characterized in that, The mass ratio of the upconversion nanomaterial to Ag2S quantum dots is (1.3~1.51):1; The upconversion nanomaterial has a particle size of 10-20 nm; the Ag2S quantum dots have a particle size of 4-6 nm.

3. The perovskite-based nanomaterial according to claim 1, characterized in that, Yb in the core of the upconversion nanomaterial 3+ The molar concentration of doping is 12%~15%; Er 3+ The molar concentration of doping is 1% to 1.5%; The thickness of the shell of the upconversion nanomaterial is 3~7nm; The surface of the perovskite-based nanomaterial is also modified with amino groups, which are obtained by reacting polyethyleneimine with the perovskite-based nanomaterial.

4. A method for preparing the perovskite-based nanomaterial according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Under an inert atmosphere, ytterbium salt, yttrium salt, erbium salt, sodium salt, oleic acid, 1-octadecene and oleylamine were mixed and heated to react. Then, the mixture was mixed with an alcoholic solution of CsF, and after heating to remove the alcoholic solution, a co-precipitation reaction was carried out to purify and obtain Yb. 3+ / Er 3+ Doped Cs2NaYF6 nanoparticles were dispersed in an organic solvent for later use. (2) Under an inert atmosphere, yttrium salt, sodium salt, oleic acid, 1-octadecene and oleylamine are mixed and heated to react, and Yb is added. 3 + / Er 3+ A solution of doped Cs2NaYF6 nanoparticles and an alcoholic solution of CsF were subjected to a co-precipitation reaction after the alcoholic solution was removed by heating. The resulting upconversion nanomaterials were purified and dispersed in an organic solvent for later use. (3) The upconversion nanomaterial solution was mixed with oleic acid, 1-octadecene, dodecyl mercaptan and silver diethyldithiocarbamate, and heated to obtain a reaction solution; then a coprecipitation reaction was carried out to purify the perovskite-based nanomaterial, which was then dispersed in an organic solvent for later use. (4) Add tetrafluoroborate nitrite to a mixed solution of DMF and cyclohexane and stir to mix. Add perovskite-based nanomaterial solution to react. After centrifugation, disperse the solid with DMF and add it to an alcohol-water solution of polyethyleneimine to mix and react. After purification, the product is obtained.

5. The method for preparing perovskite-based nanomaterials according to claim 4, characterized in that, In step (1), the molar ratio of ytterbium salt, yttrium salt, erbium salt and sodium salt is (1.48~1.52): 1: (8.2~8.6): (9.8~10.2); in step (2), the molar ratio of yttrium salt and sodium salt is 1: (0.98~1.02).

6. The method for preparing perovskite-based nanomaterials according to claim 4, characterized in that, In step (1) or step (2), the ytterbium salt includes Yb(Ac)3, the erbium salt includes Er(Ac)3, the yttrium salt includes Y(Ac)3, and the sodium salt includes NaAc·3H2O; the volume ratio of oleic acid, oleylamine and 1-octadecene is (198~202): (98~102): (198~202); the heating temperature is 120~130℃, and the molar ratio of CsF to sodium salt is (9.8~10.2):1; the temperature of the coprecipitation reaction is 290~330℃, and the time is 1~2 h.

7. The method for preparing perovskite-based nanomaterials according to claim 4, characterized in that, In step (3), the ratio of upconversion nanomaterials, oleic acid and 1-octadecene is 1 mmol:(3.8~4.2) mL:(9.8~10.2) mL; The heating reaction is carried out at a temperature of 65-75 °C for 30-40 min. The ratio of silver diethyldithiocarbamate to dodecyl mercaptan is 1 mmol:(468~472) mL; the temperature of the coprecipitation reaction is 120~130℃ and the time is 10~15 min.

8. The method for preparing perovskite-based nanomaterials according to claim 4, characterized in that, In step (4), the mass ratio of the polyethyleneimine to the perovskite-based nanomaterial is (2.5~3):

1.

9. The application of the perovskite-based nanomaterial according to any one of claims 1-3 in chloride detection.

10. The application according to claim 9, characterized in that, The chloride detection method is as follows: Perovskite-based nanomaterials are added to the sample to be tested. Under 980 nm laser excitation, the emission intensity of the sample to be tested is measured in the range of 300~750 nm. The concentration of chloride is calculated according to the standard curve.

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