Flexible HP-ZIF-67 (at) Au surface-enhanced Raman scattering substrate for multi-phase detection of volatile organic gas and pesticide residues, preparation method and application of flexible HP-ZIF-67 (at) Au surface-enhanced Raman scattering substrate

Abstract

The invention provides a flexible HP-ZIF-67 (at) Au surface enhanced Raman scattering substrate for multi-phase detection of volatile organic gas and pesticide residues, and a preparation method and application thereof, and belongs to the technical field of volatile organic gas and pesticide residue detection. The preparation method comprises the following steps: preparing a polystyrene microsphere template by taking polyvinylpyrrolidone, styrene and potassium persulfate as raw materials, then adding 2-methylimidazole and cobalt nitrate to obtain HP-ZIF-67 particles, dispersing the HP-ZIF-67 particles on an aluminum foil to obtain an HP-ZIF-67 substrate, and continuing to diffuse and deposit a gold nanoparticle layer to obtain the flexible HP-ZIF-67 (at) Au surface enhanced Raman scattering substrate. The flexible HP-ZIF-67 (at) Au surface enhanced Raman scattering substrate provided by the invention has the advantages of stable process, high sensitivity and multiphase detection, and a novel composite material is provided for volatile organic gas and pesticide residue detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of volatile organic gas and pesticide residue detection, and in particular relates to a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate for multiphase detection of volatile organic gas and pesticide residue, a preparation method and application thereof. Background Art

[0002] Surface enhanced Raman spectroscopy (SERS) is a new spectroscopic technique that is fast, sensitive and accurate and has been widely used in catalytic monitoring and biomedicine. The sensitivity of SERS technology depends on two enhancement mechanisms: electromagnetic enhancement mechanism (EM) and chemical enhancement mechanism (CM). The generation of EM mainly depends on the metals in the substrate, especially metals such as gold, silver and copper, which can bring strong plasma coupling. The generation of CM mainly depends on the charge transfer effect at the semiconductor-analyte interface. The coupling of EM and CM can bring significant Raman enhancement.

[0003] Metal-organic frameworks (MOFs) are versatile and customizable materials composed of metal ions and organic ligands arranged in a crystal structure. They have a wide range of applications in various scientific fields, including chemistry, biology, and materials science. ZIF-67 is a metal-organic framework material (MOF) with multiple advantages such as high selectivity, high sensitivity, good stability, good controllability, and versatility. However, the pore size of ZIF-67 is between 0.45nm and 0.56nm, which limits its detection ability. When detecting large molecules, the pores are usually blocked. The pore size of ZIF-67 can be enlarged by acid etching, but this will make ZIF-67 form a hollow structure and waste a huge internal surface area. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a flexible HP-ZIF-67@Au surface-enhanced Raman scattering substrate, a preparation method and an application for multiphase detection of volatile organic gases and pesticide residues. The present invention has the advantages of stable process, high sensitivity and multiphase detection, and provides a composite material with excellent performance for surface-enhanced Raman scattering detection of volatile organic gases and pesticide residues.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] A method for preparing a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate comprises the following steps:

[0008] (1) adding polyvinylpyrrolidone (PVP) to water, introducing nitrogen and adding styrene (ST) to mix and stir, then adding potassium persulfate (K2S2O8) aqueous solution to stir, cooling the obtained mixture, filtering to obtain an emulsion, and allowing the emulsion to stand to obtain a polystyrene microsphere template (PS template);

[0009] (2) adding cobalt nitrate (Co(NO3)2·6H2O) and the polystyrene microsphere template obtained in step (1) into a methanol solution, continuously introducing nitrogen gas and ultrasonically treating the solution, then adding 2-methylimidazole and mixing the mixture, and etching with dimethylformamide to remove PS to obtain HP-ZIF-67 particles;

[0010] (3) Adding the HP-ZIF-67 particles obtained in step (2) into dimethylformamide (DMF), dispersing the mixture on aluminum foil, and drying to obtain an HP-ZIF-67 substrate, and diffusely depositing a gold (Au) nanoparticle layer on the HP-ZIF-67 substrate to obtain the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au).

[0011] Furthermore, in step (1), the styrene needs to be washed with a NaOH solution before use, and then washed with deionized water until it becomes neutral, wherein the concentration of the NaOH solution used is 10%wt.

[0012] Furthermore, in step (1), the usage ratio of polyvinyl pyrrolidone, styrene and potassium persulfate aqueous solution is 0.5 g: 13 mL: 20 mL.

[0013] Furthermore, in step (1), the concentration of the potassium persulfate aqueous solution is 0.3 g / 20 mL.

[0014] Furthermore, in step (1), styrene (ST) is added and mixed and stirred, and the mixture is heated to 70° C. and stirred at 70° C. for 30 minutes.

[0015] Furthermore, in step (1), the polystyrene microsphere template needs to be dried at 60° C. for 24 hours under a vacuum environment before use.

[0016] Furthermore, in step (2), the usage ratio of cobalt nitrate (Co(NO3)2·6H2O), polystyrene microsphere template and 2-methylimidazole is 1.5 mmol: 0.25 g: 6 mmol.

[0017] Furthermore, in step (2), the mixing and stirring is carried out at a temperature of 35° C. and for 12 hours.

[0018] Furthermore, in step (3), a vacuum coating machine is used to diffusely deposit a gold nanoparticle layer on the HP-ZIF-67 substrate.

[0019] Furthermore, in step (3), the thickness of the gold nanoparticle layer is 20-260 nm, and optimally 180 nm.

[0020] Furthermore, in step (3), the ratio of the HP-ZIF-67 particles to dimethylformamide (DMF) is 1 mg: 1 mL.

[0021] The second technical solution of the present invention:

[0022] A flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate prepared by the preparation method.

[0023] The third technical solution of the present invention:

[0024] The flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate is used in multiphase detection of volatile organic gases and pesticide residues.

[0025] Furthermore, the detection limit for the volatile organic gases (VOCs) is 1000 ppm, and the detection limit for the pesticides is 800 ppb.

[0026] Furthermore, the volatile organic gas is benzaldehyde, and the pesticide is thiram.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The flexible HP-ZIF-67@Au surface-enhanced Raman scattering substrate for multiphase detection of volatile organic gases and pesticide residues provided by the present invention is synthesized and prepared by a one-pot method, has fewer types of preparation raw materials, a simple synthesis method, and convenient control of the gold nanoparticle deposition process, so that the product quality is relatively stable. A polystyrene microsphere template is used to form a porous structure on the ZIF-67 surface. The presence of the porous structure allows the detection target molecules to enter the porous ZIF-67 structure, thereby improving the system's capture performance of organic target molecules in gas-liquid two phases. The porous structure also makes the distribution of the gold nanoparticle layer more reasonable, greatly enhances the electromagnetic field intensity, forms a "hot spot" array, and enhances the detection sensitivity of the HP-ZIF-67@Au surface-enhanced Raman scattering substrate. The present invention has the advantages of stable process, high sensitivity and multiphase detection, and provides a composite material with excellent performance for surface-enhanced Raman scattering detection of volatile organic gases and pesticide residues. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 is the FDTD simulated electric field distribution diagram of the HP-ZIF-67 particles obtained in step (2) of Example 1, a1, a2, and a3 are respectively the simulated diagrams of the electric field distribution of the HP-ZIF-67 particles in the xz cross section at different magnifications of regions I and II, wherein i and ii represent the local magnified diagrams of the electric field enhancement regions in regions I and II, respectively, wherein E / E0 is the electromagnetic field enhancement factor, specifically the ratio of the actual electromagnetic field intensity of the region to the reference value of the electromagnetic field intensity under the simulation of the FDTD simulation software, and the larger the ratio, the higher the electromagnetic field intensity;

[0031] Figure 2 The SERS substrate HP-ZIF-67@Au obtained in Example 1 was detected at a concentration of 10 under 532nm and 633nm excitation light. -3 SERS spectrum of MB probe molecule;

[0032] Figure 3 This is the Raman spectrum of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au) prepared in Example 1 of the present invention for the detection of benzaldehyde gas at a concentration of 1000 ppm;

[0033] Figure 4 The SERS test results of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au) prepared in Example 1 of the present invention on the pesticide thiram of different concentrations;

[0034] Figure 5 The HP-ZIF-67@Au surface enhanced Raman scattering substrate with different gold nanoparticle layer thickness prepared in Example 2-11 of the present invention has a concentration of 10 -4 M R6G molecular solution 612cm -1 Dotted line graph of the Raman signal intensity at the characteristic peak as the thickness of the gold nanoparticle layer changes. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The embodiment of the present invention provides a method for preparing a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate, comprising the following steps:

[0041] (1) adding polyvinylpyrrolidone (PVP) to water, introducing nitrogen and adding styrene (ST) to mix and stir, then adding potassium persulfate (K2S2O8) aqueous solution to stir, cooling the obtained mixture, filtering to obtain an emulsion, and allowing the emulsion to stand to obtain a polystyrene microsphere template (PS template);

[0042] (2) adding cobalt nitrate (Co(NO3)2·6H2O) and the polystyrene microsphere template obtained in step (1) into a methanol solution, continuously introducing nitrogen gas and ultrasonically treating the solution, then adding 2-methylimidazole and mixing the mixture, and etching with dimethylformamide to remove PS to obtain HP-ZIF-67 particles;

[0043] (3) Adding the HP-ZIF-67 particles obtained in step (1) into dimethylformamide (DMF), dispersing the mixture on aluminum foil, and drying to obtain an HP-ZIF-67 substrate, and diffusely depositing a gold (Au) nanoparticle layer on the HP-ZIF-67 substrate to obtain the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au).

[0044] In step (1) of a preferred embodiment of the present invention, the styrene is washed with a NaOH solution before use, and then washed with deionized water until it becomes neutral, wherein the concentration of the NaOH solution used is 10%wt.

[0045] In step (1) of a preferred embodiment of the present invention, the usage ratio of polyvinyl pyrrolidone, styrene and potassium persulfate aqueous solution is 0.5 g: 13 mL: 20 mL.

[0046] In step (1) of a preferred embodiment of the present invention, the concentration of the potassium persulfate aqueous solution is 0.3 g / 20 mL.

[0047] In step (1) of the preferred embodiment of the present invention, styrene (ST) is added and mixed with stirring, and the mixture is heated to 70° C. and stirred at 70° C. for 30 minutes.

[0048] In step (1) of a preferred embodiment of the present invention, the polystyrene microsphere template needs to be dried at 60° C. for 24 hours under a vacuum environment before use.

[0049] In step (2) of a preferred embodiment of the present invention, the usage ratio of cobalt nitrate (Co(NO3)2·6H2O), polystyrene microsphere template and 2-methylimidazole is 1.5 mmol: 0.25 g: 6 mmol.

[0050] In step (2) of a preferred embodiment of the present invention, the mixing and stirring is carried out at a temperature of 35° C. and for 12 hours.

[0051] In step (3) of the preferred embodiment of the present invention, a vacuum coating machine is used to diffusely deposit a gold nanoparticle layer on the HP-ZIF-67 substrate.

[0052] In step (3) of a preferred embodiment of the present invention, the thickness of the gold nanoparticle layer is 20-260 nm, and optimally 180 nm.

[0053] In step (3) of a preferred embodiment of the present invention, the ratio of the HP-ZIF-67 particles to dimethylformamide (DMF) is 1 mg: 1 mL.

[0054] The embodiment of the present invention also provides a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate prepared by the above preparation method.

[0055] The technical solution of the present invention is further illustrated by the following embodiments.

[0056] Example 1

[0057] A method for preparing a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate comprises the following steps:

[0058] (1) 13 mL of styrene (ST) was washed with 10 mL of 10 wt% NaOH solution and then washed with deionized water until neutral, 0.5 g of polyvinyl pyrrolidone (PVP) was added to a flask containing 100 mL of water, styrene (ST) was added while slowly stirring and continuously introducing nitrogen, the mixture was heated to 70°C and stirred at 70°C for 30 min, then 20 mL of an aqueous solution containing 0.3 g of K2S2O8 was injected into the flask to initiate the polymerization reaction of styrene, after the reaction was completed, the obtained mixture was cooled at room temperature, and then filtered to obtain an emulsion, the obtained emulsion was assembled into a regular polystyrene microsphere template (PS template) after standing for at least 48 h, and then the PS template was washed with deionized water and vacuum dried at 60°C for 24 h;

[0059] (2) 0.4365 g (1.5 mmol) of cobalt nitrate (Co(NO3)2·6H2O) and 0.25 g of the PS template obtained in step (1) were added to 80 mL of methanol solution, nitrogen was continuously introduced for 15 min, the solution was ultrasonically treated for 60 min, and then poured into a 250 mL flask and gently stirred to obtain a mixed solution A; 0.4926 g (6 mmol) of 2-methylimidazole was added to 80 mL of methanol solution, stirred to dissolve, and nitrogen was continuously introduced for 15 min to obtain a mixed solution B, and the mixed solution B was poured into the flask containing the mixed solution A under stirring to react, and the mixture was stirred at 35°C for 12 h, and finally the PS was etched away with DMF within 48 h, the product was washed with DMF and methanol, and then dried at 60°C for 12 h to obtain HP-ZIF-67 particles with a hierarchical pore structure;

[0060] (3) 1 mg of the HP-ZIF-67 particles obtained in step (2) was added to 1 mL of dimethylformamide (DMF) and slowly stirred. Then 30 μL of the mixture was dispersed on an aluminum foil and dried at 60° C. for 6 h to obtain an HP-ZIF-67 substrate. A gold (Au) nanoparticle layer with a thickness of 150 nm was diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine to obtain a flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au).

[0061] Figure 1 is the FDTD simulated electric field distribution diagram of the HP-ZIF-67 particles obtained in step (2) of Example 1, a1, a2, and a3 are respectively the simulated diagrams of the electric field distribution of the HP-ZIF-67 particles in the xz cross section at different magnifications in regions I and II, wherein i and ii represent the local magnified diagrams of the electric field enhancement regions in regions I and II, respectively, wherein E / E0 is the electromagnetic field enhancement factor, specifically the ratio of the actual electromagnetic field intensity of the region to the reference value of the electromagnetic field intensity under the simulation of the FDTD simulation software, and the larger the ratio, the higher the electromagnetic field intensity; Figure 1 It can be seen that the electric field intensity is higher in the gaps between the pores of HP-ZIF-67 particles. The presence of the pore array enhances the local electric field on the surface of HP-ZIF-67 and enhances the sensitivity of SERS detection.

[0062] 30 μL of MB probe molecule solution was directly added to the SERS substrate HP-ZIF-67@Au prepared in Example 1, and then dried at 60°C for 5 min before testing. Figure 2 The SERS substrate HP-ZIF-67@Au obtained in Example 1 was detected at a concentration of 10 under 532nm and 633nm excitation light. -3 The SERS spectrum of MB probe molecules is shown in Figure 2. Figure 2 It can be seen that compared with the excitation light with a wavelength of 532 nm, the excitation light with a wavelength of 633 nm is more suitable for the HP-ZIF-67@Au SERS substrate and is more conducive to the SERS detection of the target molecules.

[0063] A 100 ppm 4-ATP ethanol solution and a 1000 ppm benzaldehyde ethanol solution were prepared, and the SERS substrate HP-ZIF-67@Au prepared in Example 1 was vacuum treated at 120°C for 2 h to remove other substances adsorbed in ZIF-67, and then 1 mL of the 4-ATP solution was dropped onto a heating table in a 30 cm×20 cm×80 cm sealed box, and the SERS substrate HP-ZIF-67@Au was placed on top of it. The 4-ATP solution was heated to evaporate for 40 min, and then 80 μL of the benzaldehyde ethanol solution was dropped onto the heating table and heated to evaporate for 4 hours. Finally, the substrate was taken out and detected normally under a Raman instrument. Figure 3 The Raman spectrum of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au) prepared in Example 1 of the present invention for the detection of 1000ppm concentration of benzaldehyde gas is shown in FIG. Figure 3 It can be seen that 4-ATP as a labeling molecule can greatly increase the detection sensitivity of the present invention to benzaldehyde gas, and the present invention has an extremely high detection sensitivity to benzaldehyde gas.

[0064] 30 μL of thiram solution of different concentrations was directly added to the surface of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au) prepared in Example 1, and then dried at 60°C for 5 min before testing. Figure 4 The SERS test results of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate (SERS substrate HP-ZIF-67@Au) prepared in Example 1 of the present invention on the pesticide thiram of different concentrations are shown in FIG. Figure 4 It can be seen that the present invention has extremely high detection performance and detection sensitivity for the pesticide thiram, and its detection limit concentration for the pesticide thiram reaches 800 ppb.

[0065] Example 2

[0066] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 20 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0067] Example 3

[0068] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 40 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0069] Example 3

[0070] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 60 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0071] Example 4

[0072] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 80 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0073] Example 5

[0074] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 120 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0075] Example 6

[0076] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 150 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0077] Example 7

[0078] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 180 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0079] Example 8

[0080] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 200 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0081] Example 9

[0082] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 220 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0083] Example 10

[0084] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 240 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0085] Embodiment 11

[0086] The same as Example 1, except that a gold (Au) nanoparticle layer with a thickness of 260 nm is diffusely deposited on the HP-ZIF-67 substrate using a vacuum coating machine.

[0087] 30 μL of R6G molecular solution was directly added dropwise onto the HP-ZIF-67@Au surface enhanced Raman scattering substrate prepared in Example 2-11, and then dried at 60° C. for 5 min before testing.

[0088] Figure 5 The HP-ZIF-67@Au surface enhanced Raman scattering substrate with different gold nanoparticle layer thickness prepared in Example 2-11 of the present invention has a concentration of 10 -4 M R6G molecular solution 612cm -1 The dotted line graph of the Raman signal intensity at the characteristic peak as the thickness of the gold nanoparticle layer changes, Figure 5It can be seen that the intensity of the R6G characteristic signal reaches an extreme value at 40nm and then decreases rapidly. After a short period of stability, it rises rapidly until the thickness of the gold nanoparticle layer reaches 180nm, when the signal intensity reaches the strongest. As the thickness of the gold nanoparticle layer further increases, the signal intensity decreases. Therefore, the signal is better when the thickness of the gold nanoparticle layer is 120-260nm, and the signal intensity is best at 180nm.

[0089] Comparative Example 1

[0090] A flexible surface enhanced Raman substrate material is prepared according to the method of Example 1 in the patent application number CN202210841729.6.

[0091] The present invention uses a polystyrene microsphere template to etch the surface of ZIF-67 to obtain a surface with a uniform and ordered pore structure, so that the distribution of gold nanoparticles is more conducive to the appearance of surface enhanced Raman scattering "hotspot" areas. Compared with the patent with application number 202210841729.6, the distribution of gold nanoparticles on the surface of the present invention is more orderly and the Raman intensity is stronger. The present invention can detect target molecules in liquids and gases, and has a wider range of detection applications.

[0092] Comparative Example 2

[0093] A surface enhanced Raman scattering substrate was prepared according to the method of Example 1 in the patent application number CN202211674068.9.

[0094] The HP-ZIF-67 of the present invention is synthesized using a one-pot method, and its synthesis steps are simple and the morphology of the synthetic product is stable. Compared with the patent application number 202211674068.9, the SERS substrate synthesis process of the present invention is simpler, the quality of the synthetic product is more stable, the synthesis cost is lower, the detection sensitivity and accuracy are higher, and the present invention can detect target molecules in liquids and gases, and the detection application range is wider.

[0095] Comparative Example 3

[0096] A surface enhanced Raman scattering substrate was prepared according to the method of Example 1 in the patent application number CN202410366191.7, in which gold nanoparticles were replaced with silver nanoparticles, and the magnetic ZIF-67 was modified by using 3-aminopropyltriethoxysilane, which was then mixed with a colloidal solution of silver nanoparticles to load it onto ZIF-67.

[0097] The detection limit of the surface enhanced Raman scattering substrate prepared in comparative example 3 for MG residue in water is 8.7×10 -10 M, and the detection limit of the pesticide bispyribac in the present invention is 800ppb. The present invention can detect target molecules in gas and liquid and has multi-phase detection capability.

[0098] Comparative Example 4

[0099] The surface enhanced Raman scattering substrate was prepared according to the method of Example 1 in the patent application number CN202410332062.6. In this patent, the gold nanoparticles were replaced with a composite system of gold nanoparticles and gold nanowires, and the detection limit of MC-LR reached 5×10 -9 Compared with the present invention, the manufacturing process of the above patent is more complicated and the production cost is higher.

[0100] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a flexible HP-ZIF-67@Au surface-enhanced Raman scattering substrate, characterized in that: The following steps are involved: (1) adding polyvinyl pyrrolidone to water, introducing nitrogen and adding styrene to mix and stir, then adding potassium persulfate aqueous solution and stirring, cooling the obtained mixture, filtering to obtain an emulsion, and allowing the emulsion to stand to obtain a polystyrene microsphere template; (2) adding cobalt nitrate and the polystyrene microsphere template obtained in step (1) into a methanol solution, continuously introducing nitrogen gas and ultrasonically treating the solution, then adding 2-methylimidazole and mixing the mixture, and etching the mixture with dimethylformamide to obtain HP-ZIF-67 particles; (3) Adding the HP-ZIF-67 particles obtained in step (2) into dimethylformamide, dispersing the mixture on aluminum foil, and drying to obtain an HP-ZIF-67 substrate, and diffusely depositing a gold nanoparticle layer on the HP-ZIF-67 substrate to obtain the flexible HP-ZIF-67@Au surface-enhanced Raman scattering substrate.

2. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (1), the usage ratio of polyvinyl pyrrolidone, styrene and potassium persulfate aqueous solution is 0.5 g: 13 mL: 20 mL.

3. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (1), each milliliter of the potassium persulfate aqueous solution contains 0.015 g of potassium persulfate.

4. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (2), the usage ratio of the cobalt nitrate, the polystyrene microsphere template and the 2-methylimidazole is 1.5 mmol: 0.25 g: 6 mmol.

5. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (2), the mixing and stirring is carried out at a temperature of 35° C. and for 12 hours.

6. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (3), a vacuum coating machine is used to diffusely deposit a gold nanoparticle layer on the HP-ZIF-67 substrate.

7. The method for preparing the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate according to claim 1, characterized in that: In step (3), the thickness of the gold nanoparticle layer is 20-260 nm.

8. A flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the flexible HP-ZIF-67@Au surface enhanced Raman scattering substrate as claimed in claim 8 in multiphase detection of volatile organic gases and pesticide residues.

10. The use according to claim 9, characterized in that: The detection limit for the volatile organic gas is 1000 ppm, and the detection limit for the pesticide is 800 ppb.

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