Capillary-based semiconductor sers active substrate and process for its preparation

Abstract

The application relates to a capillary-based semiconductor SERS active substrate and a preparation process method thereof, and belongs to the technical field of environmental science detection. The capillary-based semiconductor SERS active substrate is a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8. ZnO@ZIF-8 nanoparticles are dispersed in an ethanol solution of 4-MBA, stirring is carried out, the obtained ZnO@ZIF-8 / 4-MBA sample is flushed to remove free 4-MBA molecules on the surface of the ZnO@ZIF-8 nanoparticles; the purified ZnO@ZIF-8 / 4-MBA is again dispersed in an ethanol solution; the solution obtained in step 1 is injected into a capillary, drying is carried out, and the ZnO@ZIF-8 / 4-MBA is attached to the inside of the capillary. The operation method is simple and efficient.

Description

Technical Field

[0001] This invention relates to a capillary-based semiconductor SERS active substrate and its preparation process, belonging to the field of environmental science detection technology. Background Technology

[0002] With the continuous development of modern industry and agriculture, a large number of heavy metal-related materials and products (pesticides, fertilizers, gasoline, batteries, etc.) are used in people's daily production and life through various mining, processing, and smelting methods. This production and application inevitably brings about heavy metal pollution problems. Coupled with the indiscriminate discharge of industrial wastewater, heavy metal ion pollution has become increasingly serious in recent years, posing a serious threat to the health of organisms and the sustainable development of the environment. Therefore, developing economical, rapid, highly sensitive, and specific methods for detecting heavy metal ions is crucial for early warning of heavy metal pollution. Currently, the main methods for detecting heavy metals include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, and high-performance liquid chromatography. These methods generally require expensive and complex instruments and have drawbacks such as long testing cycles and complex analytical procedures. Therefore, in order to achieve sustainable development of human environment and organism health, developing simple, rapid, low-cost, highly sensitive, and selective heavy metal ion detection and analysis technologies is of great significance.

[0003] Surface-enhanced Raman scattering (SERS) is a vibrational spectroscopy technique with high sensitivity, specificity, and short response time. It also possesses numerous inherent advantages, including resistance to photobleaching, high spectral resolution, and rich spectral fingerprint information. Currently, several methods for heavy metal ion detection using SERS sensing technology have been proposed, all achieving good detection results. For example, the invention disclosed in CN114894771B, entitled "AgNPs-modified double MOFs-derived semiconductor heterojunction SERS substrate and its preparation and application," involves the preparation and calcination of ZIF-8 and ZIF-8@ZIF-67 crystals, as well as complex chemical processes such as the silver mirror reaction. It is used for the on-site trace detection of pesticide residues on agricultural product surfaces, but the preparation process is complex.

[0004] Therefore, there is an urgent need to provide a capillary-based semiconductor SERS active substrate and its preparation process to solve the above-mentioned technical problems. This invention prepares a capillary-based semiconductor SERS active substrate for the detection and separation of metal ions. The preparation is simple and the operation is straightforward. Compared with the aforementioned patents, it has better chemical stability and biocompatibility, and can be stably tested for a long time in complex chemical environments, ensuring the reliability of the detection results. Summary of the Invention

[0005] To address the aforementioned problems, there is a need to provide a capillary-based semiconductor SERS active substrate and its fabrication process. A brief overview of the invention is provided below to offer a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of the present invention:

[0007] A capillary-based semiconductor SERS active substrate, wherein the capillary-based semiconductor SERS active substrate is a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8.

[0008] A method for preparing a capillary-based semiconductor SERS active substrate includes the following steps:

[0009] Step 1: Disperse ZnO@ZIF-8 nanoparticles in an ethanol solution of 4-MBA, stir, and rinse the resulting ZnO@ZIF-8 / 4-MBA sample to remove free 4-MBA molecules on the surface of the ZnO@ZIF-8 nanoparticles; the purified ZnO@ZIF-8 / 4-MBA is then dispersed again in an ethanol solution.

[0010] Step 2: Inject the solution obtained in Step 1 into the capillary tube and dry it to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary tube.

[0011] Preferably, in step 1, 1 mg of ZnO@ZIF-8 nanoparticles are dispersed in 1 mL of a 10% concentration solution. -3 In an ethanol solution of 4-MBA, stir for 2 h, then wash the resulting ZnO@ZIF-8 / 4-MBA sample with ethanol to remove free 4-MBA molecules on the surface of ZnO@ZIF-8 nanoparticles; the purified ZnO@ZIF-8 / 4-MBA is then redispersed in 1 mL of ethanol solution.

[0012] Preferred method: In step 2, 100 μL of the above solution is injected into the capillary using a syringe and dried in an oven at 60°C for 2 hours to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary.

[0013] Preferably, in step 1, the synthesis of ZnO nanoparticles includes the following steps:

[0014] Zinc acetate dihydrate was added to diethylene glycol, and the mixture was slowly heated to a certain temperature. At this temperature, the mixture was magnetically stirred to form a turbid colloidal suspension.

[0015] The colloidal suspension was cooled to room temperature and then centrifuged. The supernatant was used as a seed solution for further reactions.

[0016] Zinc acetate dihydrate was dissolved in diethylene glycol and heated to a certain temperature. Seed solution was added to the hot solution, and the temperature was raised to the set temperature. At this temperature, the mixture was magnetically stirred to generate submicron spherical ZnO particles.

[0017] ZnO nanoparticles were collected by centrifugation, washed with distilled water and anhydrous ethanol, and then dried under vacuum.

[0018] Preferred method: In step 1, 0.01 mol to 0.015 mol of zinc acetate dihydrate is added to 100 mL of diethylene glycol. The mixture is slowly heated to 160°C to 170°C and magnetically stirred at 160°C to 170°C for 1 hour to form a turbid colloidal suspension. The colloidal suspension is cooled to room temperature and centrifuged. The supernatant is used as a seed solution for further reactions. Separately, 0.01 mol to 0.015 mol of zinc acetate dihydrate is dissolved in 100 mL of diethylene glycol and slowly heated to 130°C to 135°C. 0.3 mL to 0.32 mL of the seed solution is added to the hot solution, and the temperature is rapidly increased to 160°C to 175°C. At this temperature, the mixture is magnetically stirred for 1 hour to generate submicron spherical ZnO particles. The ZnO nanoparticles are collected by centrifugation, washed with distilled water and anhydrous ethanol, and finally dried in a vacuum desiccator at 60°C for 12 hours before use.

[0019] Preferred method: In step 2, the synthesis of ZnO@ZIF-8 nanoparticles includes the following steps:

[0020] The synthesized ZnO nanoparticles were added to a DMF / H2O solution containing dissolved 2-methylimidazole;

[0021] The mixture was ultrasonically treated to disperse the ZnO nanoparticles;

[0022] The mixture was transferred to a preheated oil bath and reacted for a period of time to form ZnO@ZIF-8 nanoparticles. The nanoparticles were collected by centrifugation and washed with DMF and anhydrous ethanol.

[0023] ZnO@ZIF-8 nanoparticles were vacuum dried.

[0024] Preferred method: In step 2, 0.0204 g to 0.0205 g of synthesized ZnO nanoparticles are added to a 16 mL DMF / H2O solution containing 0.11 g to 0.115 g of 2-methylimidazole; the mixture is sonicated for 10 min to disperse the ZnO nanoparticles; the mixture is transferred to an oil bath preheated to 70 °C, and reacted at 70 °C for 3 h to form ZnO@ZIF-8 nanoparticles, which are collected by centrifugation and washed with DMF and anhydrous ethanol; the ZnO@ZIF-8 nanoparticles are dried in a vacuum desiccator at 60 °C for 12 h before use.

[0025] Preferably, it also includes step 3: detection of metal ions, including the following steps:

[0026] The capillary-based semiconductor SERS active substrate prepared in step 2 is connected to a syringe via a Teflon tube and mounted on a microscope glass slide with double-sided tape. The test solution is injected into the capillary using the syringe, and air is injected into the capillary to move the sample. A mark is drawn on the surface of the microscope slide every 5 mm to determine the position of the moving sample solution, and Raman testing is performed.

[0027] The present invention has the following beneficial effects:

[0028] 1. This invention develops a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8, which has a simple and efficient operation method;

[0029] 2. Capillary-based semiconductor SERS active substrates can detect and separate a variety of metal ions without the need for pretreatment or incubation time. Attached Figure Description

[0030] Figure 1 Scanning electron microscope (SEM) images of ZnO nanoparticles obtained in the examples;

[0031] Figure 2 Scanning electron microscope (SEM) images of ZnO@ZIF-8 nanoparticles obtained in the examples;

[0032] Figure 3 Transmission electron microscopy (TEM) images of ZnO@ZIF-8 nanoparticles obtained in the examples;

[0033] Figure 4 The image shows the SERS signal of ZnO@ZIF-8 nanoparticles for 4-mercaptobenzoic acid obtained in the example.

[0034] Figure 5 Here is an actual photograph of the capillary-based semiconductor SERS active substrate obtained in the example;

[0035] Figure 6This example compares the SERS signals obtained from the detection of different metal ions on the capillary-based semiconductor SERS active substrate.

[0036] Figure 7 The diagram shows the separation and differentiation of lead ions and ferrous ions on the capillary-based semiconductor SERS active substrate obtained in the example.

[0037] Figure 8 This is a magnified view of the separation of lead ions and ferrous ions on the capillary-based semiconductor SERS active substrate obtained in the example. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0039] Specific implementation method one: Combining Figure 1-8 This embodiment describes a capillary-based semiconductor SERS active substrate, which is a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8.

[0040] Specific Implementation Method Two: Combining Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate, used to prepare a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8, including the following steps:

[0041] Step 1: Disperse ZnO@ZIF-8 nanoparticles in an ethanol solution of 4-MBA, stir, and rinse the resulting ZnO@ZIF-8 / 4-MBA sample to remove free 4-MBA molecules on the surface of the ZnO@ZIF-8 nanoparticles; the purified ZnO@ZIF-8 / 4-MBA is then dispersed again in an ethanol solution.

[0042] Step 2: Inject the solution obtained in Step 1 into the capillary tube and dry it to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary tube; thus realizing the capillary base for the separation and detection of multiple metal ions.

[0043] Specific implementation method three: Combining Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. In step 1, 1 mg of ZnO@ZIF-8 nanoparticles are dispersed in 1 mL of a 10% concentration... -3 In an ethanol solution of 4-MBA, the mixture was stirred vigorously for 2 hours. The resulting ZnO@ZIF-8 / 4-MBA sample was then washed several times with ethanol to remove free 4-MBA molecules from the surface of ZnO@ZIF-8 nanoparticles. The purified ZnO@ZIF-8 / 4-MBA was then redispersed in 1 mL of ethanol solution.

[0044] Specific implementation method four: Combination Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. In step 2, 100 μL of the above solution is injected into the capillary using a syringe and dried in an oven at 60°C for 2 hours to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary.

[0045] Specific Implementation Method Five: Combining Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. Step 1, the synthesis of ZnO nanoparticles, includes the following steps:

[0046] Zinc acetate dihydrate was added to diethylene glycol, and the mixture was slowly heated to a certain temperature. At this temperature, the mixture was magnetically stirred to form a turbid colloidal suspension.

[0047] The colloidal suspension was cooled to room temperature and then centrifuged. The supernatant was used as a seed solution for further reactions.

[0048] Zinc acetate dihydrate was dissolved in diethylene glycol and heated to a certain temperature. Seed solution was added to the hot solution, and the temperature was raised to the set temperature. At this temperature, the mixture was magnetically stirred to generate submicron spherical ZnO particles.

[0049] ZnO nanoparticles were collected by centrifugation, washed with distilled water and anhydrous ethanol, and then dried under vacuum.

[0050] Specific Implementation Method Six: Combination Figure 1-8This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. In step 1, 0.01 mol of zinc acetate dihydrate is added to 100 mL of diethylene glycol. The mixture is slowly heated to 160°C and magnetically stirred at 160°C–170°C for 1 hour to form a turbid colloidal suspension. The colloidal suspension is cooled to room temperature and centrifuged. The supernatant is used as a seed solution for further reactions. Separately, 0.01 mol of zinc acetate dihydrate is dissolved in 100 mL of diethylene glycol, and the temperature is slowly raised to 130°C. 0.3 mL–0.32 mL of the seed solution is added to the hot solution, and the temperature is rapidly increased to 160°C. At this temperature, the mixture is magnetically stirred for 1 hour to generate submicron spherical ZnO particles. The ZnO nanoparticles are collected by centrifugation, washed several times with distilled water and anhydrous ethanol, and finally dried in a vacuum desiccator at 60°C for 12 hours before use.

[0051] Specific implementation method seven: Combination Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. Step 2, the synthesis of ZnO@ZIF-8 nanoparticles, includes the following steps:

[0052] The synthesized ZnO nanoparticles were added to a DMF / H2O solution containing dissolved 2-methylimidazole;

[0053] The mixture was ultrasonically treated to disperse the ZnO nanoparticles;

[0054] The mixture was transferred to a preheated oil bath and reacted for a period of time to form ZnO@ZIF-8 nanoparticles. The nanoparticles were collected by centrifugation and washed several times with DMF and anhydrous ethanol.

[0055] ZnO@ZIF-8 nanoparticles were vacuum dried.

[0056] Specific implementation method eight: Combination Figure 1-8 This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate. In step 2, 0.0204 g of synthesized ZnO nanoparticles are added to a 16 mL LDM / H2O solution (volume ratio 10:1) containing 0.11 g of 2-methylimidazole. The mixture is ultrasonically treated for 10 min to disperse the ZnO nanoparticles. Then, the mixture is transferred to an oil bath preheated to 70 °C and reacted at 70 °C for 3 h to form ZnO@ZIF-8 nanoparticles. These nanoparticles are collected by centrifugation and washed several times with DMF and anhydrous ethanol. Finally, the ZnO@ZIF-8 nanoparticles are dried in a vacuum desiccator at 60 °C for 12 h before use.

[0057] Specific Implementation Method Nine: Combining Figure 1-8This embodiment describes a method for preparing a capillary-based semiconductor SERS active substrate, which further includes step 3: detection of metal ions, comprising the following steps:

[0058] The capillary-based semiconductor SERS active substrate prepared in step 2 is connected to a syringe via a Teflon tube and mounted on a microscope glass slide with double-sided tape. The test solution is injected into the capillary using the syringe, and air is injected into the capillary to move the sample. A mark is drawn on the surface of the microscope slide every 5 mm to determine the position of the moving sample solution, and Raman testing is performed.

[0059] Example 1:

[0060] A capillary-based semiconductor SERS active substrate for realizing the separation and detection of multiple metal ions and its preparation process are specifically carried out according to the following steps:

[0061] Step 1: Synthesis of ZnO nanoparticles:

[0062] 0.01 mol of zinc acetate dihydrate was added to 100 mL of diethylene glycol, heated to 160 °C, and magnetically stirred for 1 h. The resulting solution was cooled to room temperature, centrifuged, and the supernatant was used as a seed solution for further reactions. Separately, 0.01 mol of zinc acetate dihydrate was dissolved in 100 mL of diethylene glycol, heated to 130 °C, and 0.3 mL of the seed solution was added to the hot solution. The temperature was raised to 160 °C, magnetically stirred for 1 h, and the generated ZnO nanoparticles were collected by centrifugation. The nanoparticles were washed several times with distilled water and anhydrous ethanol and dried in a vacuum desiccator at 60 °C for 12 h. Figure 1 The image shows a scanning electron microscope (SEM) image of ZnO nanoparticles, which reveals that the material consists of monodisperse spherical particles with uniform size.

[0063] Step 2, Synthesis of ZnO@ZIF-8 Nanoparticles:

[0064] 0.0204 g of ZnO nanoparticles were added to a 16 mL LDM / H2O solution (volume ratio 10:1) containing 0.11 g of 2-methylimidazole; the mixture was sonicated for 10 min; the mixture was then transferred to an oil bath and reacted at 70 °C for 3 h. The ZnO@ZIF-8 nanoparticles were collected by centrifugation and washed several times with DMF and anhydrous ethanol. Finally, the mixture was dried in a vacuum desiccator at 60 °C for 12 h. Figure 2 The image shows a scanning electron microscope image of ZnO@ZIF-8 nanoparticles, which reveals that the surface is covered with sharp edges characteristic of ZIF-8. Figure 3 The transmission electron microscope image of ZnO@ZIF-8 nanoparticles shows a clear boundary between the ZnO core and the ZIF-8 shell, indicating that ZnO was successfully converted into ZIF-8.

[0065] Step 3: Preparation of capillary-based semiconductor SERS active substrate:

[0066] 1 mg of ZnO@ZIF-8 nanoparticles were dispersed in 1 mL of a 10% concentration solution. -3 In an ethanol solution of M-MBA, stir vigorously for 2 hours, rinse several times with ethanol, and then redisperse in 1 mL of ethanol solution; inject 100 μL of the above solution into a capillary tube using a syringe, and dry in an oven at 60 °C for 2 hours. Figure 4 The image shows the SERS signal of ZnO@ZIF-8 nanoparticles against 4-mercaptobenzoic acid, indicating that ZnO@ZIF-8 nanoparticles have strong SERS ability. Figure 5 An actual photograph of a capillary-based semiconductor SERS active substrate;

[0067] Step 4: Detection of metal ions:

[0068] The prepared capillary-based semiconductor SERS active substrate was connected to a syringe using a Teflon tube and mounted on a microscope slide using double-sided tape. Different metal ion solutions were prepared using deionized water as the solvent; silver and mercury ion solutions were prepared using nitrates, while the remaining metal ion solutions were prepared using metal chlorides. 10 μL of the metal ion solution was injected into the capillary using a syringe, and air was injected into the capillary to move the sample for Raman testing. Data acquisition time was 30 seconds, accumulated once, with a power of 40 mW. The instrument used was a confocal micro Raman spectrometer (RTS2-301-DL) purchased from Beijing Zhuoli Hanguang Instrument Co., Ltd. Figure 6 This example compares the SERS signals obtained from the detection of different metal ions on the capillary-based semiconductor SERS active substrate.

[0069] Mark the microscope slide every 5 mm to determine the position of the moving sample solution. Take equal volumes and equimolar amounts of lead and ferrous ion solutions, mix them thoroughly, and inject 3 μL into the vicinity of the capillary inlet using a syringe. Inject air into the capillary through the syringe to move the sample to the initial point of "0 mm" in the capillary. Record the SERS spectrum. The data acquisition time is 30 s, accumulated once, and the power is 40 mW. Then move the sample to a position about 10 mm away from the initial point and record the SERS spectrum again. Repeat this process until the SERS band of the benzene ring C=C breathing vibration mode corresponds to only one of the two metal ions identified in the above experiment. Figure 7 This diagram illustrates the separation and differentiation of lead ions and ferrous ions on a capillary-based semiconductor SERS active substrate. Figure 8This is a magnified view of the separation of lead ions and ferrous ions on a capillary-based semiconductor SERS active substrate. It can be seen that when the liquid column moves to 90 mm from the initial point in the capillary, the SERS band of the benzene ring C=C breathing vibration mode corresponds to only one type of ion. Lead ions and ferrous ions can be distinguished based on the changes in the SERS signal. The parameters in this embodiment are the optimal parameters.

[0070] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 method for separating and detecting multiple metal ions based on a capillary-based semiconductor SERS active substrate, characterized in that: The capillary-based semiconductor SERS active substrate is a capillary-based semiconductor SERS active substrate based on semiconductor ZnO@ZIF-8; The preparation of the capillary-based semiconductor SERS active substrate includes the following steps: Step 1: Disperse ZnO@ZIF-8 nanoparticles in an ethanol solution of 4-MBA, stir, and wash the resulting ZnO@ZIF-8 / 4-MBA sample with ethanol to remove free 4-MBA molecules on the surface of ZnO@ZIF-8 nanoparticles; the purified ZnO@ZIF-8 / 4-MBA is then dispersed again in an ethanol solution. Step 2: Inject the solution obtained in Step 1 into the capillary tube and dry it to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary tube; The separation and detection of multiple metal ions includes the following steps: The capillary-based semiconductor SERS active substrate obtained in step 2 was connected to a syringe via a Teflon tube and mounted on a microscope glass slide with double-sided tape. The test solution was injected into the capillary using the syringe, and air was injected into it to move the sample. A mark was drawn on the surface of the microscope slide every 5 mm to determine the position of the moving sample solution, and Raman testing was performed.

2. The method according to claim 1, characterized in that: In step 1, 1 mg of ZnO@ZIF-8 nanoparticles were dispersed in 1 mL of a 10% concentration solution. -3 In an ethanol solution of 4-MBA, the mixture was stirred for 2 h. The resulting ZnO@ZIF-8 / 4-MBA sample was then washed with ethanol to remove free 4-MBA molecules from the surface of the ZnO@ZIF-8 nanoparticles. The purified ZnO@ZIF-8 / 4-MBA was then redispersed in 1 mL of ethanol solution.

3. The method according to claim 2, characterized in that: In step 2, 100 μL of the solution obtained in step 1 is injected into the capillary using a syringe and dried in an oven at 60 °C for 2 h to allow ZnO@ZIF-8 / 4-MBA to adhere to the inside of the capillary.

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