Preparation method and application of ordered silver nanoparticle-bismuth nanosheet-copper mesh array

Abstract

This invention relates to a method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array. First, bismuth nanosheets are grown on the surface of a copper mesh through an etching reaction using an immersion method. Then, silver nanoparticles are sputtered onto the surface of the bismuth nanosheets, resulting in an ordered silver nanoparticle@bismuth nanosheet@copper mesh array film. This array film is then immersed in a 4-p-aminobenzaldehyde (4-ABZ) solution, adsorbing 4-ABZ molecules onto the surface of the silver nanoparticle@bismuth nanosheet@copper mesh array as signal probe molecules. The silver nanoparticle@bismuth nanosheet@copper mesh array with adsorbed 4-ABZ molecules is then placed as a substrate in a packaging environment containing seafood, meat, or other meat-derived foods. The SERS signal intensity of the 4-ABZ molecules on the substrate surface is used to monitor the freshness of the meat-derived foods. As the freshness of the meat-derived foods decreases, the SERS signal of the 4-ABZ molecules on the substrate surface gradually decreases. Meanwhile, the silver nanoparticle@bismuth nanosheet@copper mesh array also exhibits excellent SERS signal response and signal uniformity for organic dye pollutant molecules such as rhodamine 6G and 4-aminobenzylthiophenol (4-ATP), and has important application prospects in the field of environmental monitoring.

Description

Technical Field

[0001] This invention belongs to the field of analytical technology, specifically relating to a method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array. Background Technology

[0002] In recent years, food safety and quality issues have become increasingly prominent, especially in terms of public health, where food spoilage can spread diseases. During food spoilage, particularly in the autolysis stage of meat-derived foods such as aquatic and meat products, the number of microorganisms increases dramatically, and nitrogenous compounds decompose in large quantities, forming various acidic compounds and biogenic amines. These compounds are mostly odorous and toxic, posing a threat to food safety; therefore, these gases are often used as indicators of spoilage. Currently, detection methods for meat-derived foods such as aquatic and meat products include electronic nose methods, chemical methods, and microbiological methods. However, these methods suffer from drawbacks such as long detection times, cumbersome operations, and poor reliability. Developing rapid detection technologies is of profound significance to ensure food safety and edibility. Surface-enhanced Raman scattering spectroscopy (SERS) technology possesses rapid, highly sensitive, and fingerprint-recognizable detection characteristics, making it one of the most sensitive analytical techniques and promising for rapid detection and analysis of meat-derived foods such as aquatic and meat products. However, the key to the application of SERS technology is the preparation of substrates with high SERS activity and highly uniform SERS structures to obtain high-quality, reproducible SERS signals. Generally, SERS substrates based on noble metal (gold, silver, copper) nanoparticles have higher SERS activity, so the synthesis methods of SERS substrates based on noble metal nanostructures have attracted researchers' attention.

[0003] To obtain SERS substrates with high sensitivity and good signal uniformity, methods such as synthesis and composite methods have been used to prepare large-area, uniformly ordered arrays of noble metal nanostructures for SERS substrates. For example, Yang Tianxi et al. (Biosensors and Bioelectronics, 68(2015):350-357.) used a gold nanoparticle dot-shaped magnetic nanocomposite material modified with inositol hexaphosphate as a substrate for rapid monitoring of trace drug-related biomarkers in saliva. However, the preparation of such substrates usually requires complex and costly techniques, making large-scale preparation difficult.

[0004] The patent, CN201610327475.0, entitled "A Large-Area Surface-Enhanced Raman Scattering Substrate and Its Preparation Method," describes a method that first prepares a template with a three-dimensional micron-scale structure. A layer of silver is then evaporated onto the template. After the silver evaporation, an oxide film is deposited on the surface of the silver nanoparticles, followed by another layer of silver evaporation on the film surface. This method is simple and rapid. However, it is also relatively complex to operate and makes it difficult to ensure uniformity. Therefore, developing a mature, stable, rapid, and simple method for preparing SERS substrates with controllable and uniform morphology of silver nanomaterials is of great significance. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array, thereby achieving the invention objective of preparing a fast, simple, morphology-controllable and uniform SERS substrate of silver nanomaterials.

[0006] To address the above technical problems, one of the objectives of this invention is to provide a method for preparing an ordered silver nanoparticle@bismuth nanosheet@copper mesh array, including substrate pretreatment, preparation of bismuth nanosheet@copper mesh array, and preparation of silver nanoparticle@bismuth nanosheet@copper mesh array;

[0007] S1: Substrate pretreatment

[0008] After ultrasonic cleaning, the Cu mesh is dried to obtain a clean Cu mesh with a smooth surface and uniform structure.

[0009] S2: Preparation of bismuth nanosheets@copper mesh array

[0010] A bismuth nitrate solution was prepared, and the cleaned Cu mesh was immersed in the bismuth nitrate solution. Bismuth nanosheets were grown on the surface of the cleaned Cu mesh by an etching reaction through immersion, resulting in a bismuth nanosheet@copper mesh array.

[0011] S3: Preparation of silver nanoparticles@bismuth nanosheets@copper mesh array

[0012] Silver nanoparticles were sputtered onto the surface of a bismuth nanosheet@copper mesh array using an ion sputtering instrument to obtain silver nanoparticle@bismuth nanosheet@copper mesh array.

[0013] Preferably, in S1, the diameter of the copper wires in the Cu mesh is 30-60 μm, and the spacing between the copper wires is 30-200 μm.

[0014] Preferably, in step S2, the bismuth nitrate solution is prepared by dissolving solid bismuth nitrate powder in N,N-dimethylformamide solution, and its mass fraction is 0.5% to 0.9%.

[0015] Preferably, in step S3, the control parameters of the ion sputtering instrument are set to a sputtering time of 1 to 8 minutes.

[0016] A second objective of this invention is the application of an ordered silver nanoparticle@bismuth nanosheet@copper mesh array. The silver nanoparticle@bismuth nanosheet@copper mesh array is modified with 4-p-aminobenzaldehyde (4-ABZ) probe molecules and used as a substrate for detecting the freshness of meat-derived foods. After the substrate is brought into contact with the meat-derived food, the Raman signal of the substrate is detected using a laser Raman spectrometer. The freshness of the meat-derived food is monitored based on the changes in the Raman signal. The meat-derived foods mainly refer to seafood such as shrimp and fish, as well as meat products such as pork and chicken.

[0017] Furthermore, placing silver nanoparticles@bismuth nanosheets@copper mesh array substrates modified with 4-p-aminobenzaldehyde (4-ABZ) probe molecules together with the meat-derived food to be tested in a sealed environment results in a more significant detection effect. The sealed environment can be a food packaging bag or a sealed glass container, etc.

[0018] Furthermore, the laser Raman spectrometer has an excitation wavelength of 532 nm, a laser power of 5–10 mW, and an excitation time of 2 s.

[0019] The second objective of this invention is to apply an ordered silver nanoparticle@bismuth nanosheet@copper mesh array as a substrate to perform surface-enhanced Raman scattering spectroscopy detection of organic dye pollutant molecules Rhodamine 6G and 4-aminophenylthio(4-ATP), wherein the detection is performed using a laser Raman spectrometer.

[0020] Furthermore, the surface-enhanced Raman scattering spectroscopy detection uses organic dye pollutants Rhodamine 6G and 4-aminothiophenol (4-ATP) as the detection targets, and a silver@bismuth nanosheet@copper mesh array as the substrate after being soaked in an ethanol solution of Rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) and then dried.

[0021] Furthermore, the laser Raman spectrometer has an excitation wavelength of 532 nm, a laser power of 5–10 mW, and an excitation time of 1–10 s.

[0022] By adopting the above technical solution, the technical effect achieved by this invention is as follows:

[0023] 1. This invention provides a method for preparing an ordered silver nanoparticle@bismuth nanosheet@copper mesh array. Based on an impregnation method, a high-performance composite noble metal nanostructure SERS substrate is prepared, achieving the fabrication of a large-area, uniformly distributed, and morphologically ordered silver nanoparticle@bismuth nanosheet@copper mesh array on a Cu mesh surface. This method is simple to operate and low in cost. A large-area bismuth nanosheet array is obtained through an impregnation method. Utilizing the spontaneous redox reaction between copper and bismuth ions in solution, copper reduces bismuth ions to bismuth atoms. As the spontaneous redox reaction proceeds, the bismuth atoms gradually grow into bismuth nanosheets. Silver nanoparticles are then sputtered onto the surface of the bismuth nanosheets to generate a large-area, uniformly distributed, and morphologically consistent silver nanoparticle@bismuth nanosheet@copper mesh array.

[0024] 2. The ordered silver nanoparticle@bismuth nanosheet@copper mesh array prepared by this method not only combines the high SERS activity of silver nanoparticles, but also allows the large-area ordered bismuth nanosheets to load more silver nanoparticles, further enhancing the SERS activity; at the same time, the silver nanoparticle@bismuth nanosheet array is uniformly distributed on the Cu mesh surface, ensuring good SERS signal uniformity and repeatability of the substrate.

[0025] 3. The ordered silver nanoparticles@bismuth nanosheets@copper mesh array prepared by this method has potential applications in chemical analysis, pollutant detection, and biosensors based on SERS technology. Using it as a SERS substrate can not only detect the freshness of seafood, but also enable the rapid detection and identification of organic pollutants rhodamine 6G and 4-aminobenzylthiophenol (4-ATP). It has important development significance in achieving rapid trace detection of organic pollutants in dyeing and printing wastewater through the SERS effect. Attached Figure Description

[0026] Figure 1 A schematic diagram of the preparation process of silver nanoparticles@bismuth nanosheets@copper mesh array and the detection process of seafood products;

[0027] Figure 2 Scanning electron microscope (SEM) characterization images of copper mesh;

[0028] Figure 3 SEM images of bismuth nanosheet arrays obtained after deposition for 0.5, 1, 2, and 4 hours, respectively, in Examples 1-4;

[0029] Figure 4 Transmission electron microscopy image of bismuth nanosheets;

[0030] Figure 5 EDS spectrum of bismuth nanosheets after silver evaporation for 8 min;

[0031] Figure 6 X-ray diffraction patterns of bismuth nanosheets@copper mesh array;

[0032] Figure 7 SEM images of silver nanoparticles@bismuth nanosheets@copper mesh arrays obtained after sputtering silver nanoparticles for 1, 2, 4, and 8 min;

[0033] Figure 8 X-ray diffraction patterns of silver nanoparticles@bismuth nanosheets@copper mesh array;

[0034] Figure 9 SERS spectra of silver nanoparticles@bismuth nanosheets@copper mesh array for different concentrations of 4-aminothiophenol (4-ATP);

[0035] Figure 10 SERS spectra of different concentrations of rhodamine 6G by silver nanoparticles@bismuth nanosheets@copper mesh array;

[0036] Figure 11 For the deposition of silver nanoparticles@bismuth nanosheets@copper mesh arrays at different times with a concentration of 10 -7 SERS spectrum of M Rhodamine 6G;

[0037] Figure 12 The concentration of silver nanoparticles@bismuth nanosheets@copper mesh array is 10. -3 SERS spectrum of M 4-p-aminobenzaldehyde (4-ABZ) for monitoring shrimp freshness at 40℃;

[0038] Figure 13 The concentration of silver nanoparticles@bismuth nanosheets@copper mesh array is 10. -3 SERS spectrum of M 4-p-aminobenzaldehyde (4-ABZ) for monitoring shrimp freshness at 4°C;

[0039] Figure 14 For testing, 33 points were randomly selected on a silver nanoparticle@bismuth nanosheet@copper mesh array to measure the effect on a concentration of 10. -6 SERS spectrum of Rhodamine 6G M. Detailed Implementation

[0040] The following describes specific embodiments and appendices. Figure 1-14 The present invention will be further described below.

[0041] Example 1: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array

[0042] S1. Cut the Cu mesh into 2cm×2cm pieces and clean it ultrasonically with anhydrous ethanol, acetone, and deionized water.

[0043] like Figure 2 As shown, characterization using a scanning electron microscope (SEM) reveals that the copper mesh has a smooth surface and a uniform structure, with copper wires having a diameter of approximately 30 micrometers and a spacing of approximately 30 micrometers.

[0044] S2. Dissolve bismuth nitrate powder in N,N-dimethylformamide solution and stir vigorously to form a clear solution with a bismuth nitrate mass fraction of 0.6%. Immerse the cleaned Cu mesh in the above transparent solution and place it in a water bath at 20°C for 0.5 hours. After the deposition is complete, remove the copper mesh with tweezers, rinse the surface of the copper mesh with deionized water, and dry it in a 60°C oven for 15 minutes.

[0045] S3. Place the prepared bismuth nanosheets@Cu mesh array face up in an ion sputtering instrument to sputter silver nanoparticles for 4 minutes to obtain a bismuth nanosheets@Cu mesh array modified with silver nanoparticles.

[0046] S4. The SERS performance of the silver nanoparticle@bismuth nanosheet@copper mesh array was tested. The prepared silver nanoparticle@bismuth nanosheet@copper mesh array substrate was immersed in Rhodamine 6G aqueous solutions of different concentrations. After 4 hours, it was removed and allowed to air dry. After drying, the Raman spectrum was measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 5 mW, and the excitation time was 2 seconds.

[0047] The prepared silver nanoparticles@bismuth nanosheets@copper mesh substrate were transferred to 4-aminobenzylthiophenol / ethanol solutions of different concentrations. After 4 hours, they were removed and allowed to air dry. The Raman spectra were then measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 5 mW, and the excitation time was 2 seconds.

[0048] S5. The SERS performance of the silver nanoparticle@bismuth nanosheet@copper mesh array was tested. The prepared silver nanoparticle@bismuth nanosheet@copper mesh array substrate was immersed in 4-p-aminobenzaldehyde (4-ABZ) of the same concentration for 8 hours, then removed and allowed to air dry. After drying, it was placed in a glass bottle containing shrimp meat, sealed, and then placed in an oven with the temperature set. Every so often, a sample was taken out, dried, and its Raman spectrum was measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 5 mW, and the excitation time was 2 seconds.

[0049] Example 2: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0050] The difference between this embodiment and Embodiment 1 is that the deposition time in step S2 is 1 hour.

[0051] Example 3: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0052] The difference between this embodiment and Embodiment 1 is that the deposition time in step S2 is 2 hours.

[0053] Example 4: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array

[0054] The difference between this embodiment and Embodiment 1 is that the deposition time in step S2 is 4 hours.

[0055] Example 5: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0056] The difference between this embodiment and Embodiment 1 is that the sputtering time in step S3 is 2 minutes.

[0057] Example 6: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array

[0058] The difference between this embodiment and Embodiment 1 is that the sputtering time in step S3 is 4 minutes.

[0059] Example 7: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0060] The difference between this embodiment and Embodiment 1 is that the sputtering time in step S3 is 8 minutes.

[0061] Example 8: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0062] S1. Cut the Cu mesh into 2cm×2cm pieces and clean it ultrasonically with anhydrous ethanol, acetone, and deionized water.

[0063] like Figure 2 As shown, characterization by scanning electron microscopy (SEM) reveals that the copper mesh has a smooth surface and uniform structure, with copper wires having a diameter of approximately 40 micrometers and a spacing of approximately 100 micrometers.

[0064] S2. Dissolve bismuth nitrate powder in N,N-dimethylformamide solution and stir vigorously to form a clear solution. The mass fraction of the bismuth nitrate solution is 0.5%. Immerse the cleaned Cu mesh in the above transparent solution and place it in a water bath. Control the water temperature at 20°C and the deposition time is 0.5 hours. After the deposition is complete, use tweezers to remove the copper mesh, rinse the surface of the copper mesh with deionized water, and dry it in a 60°C oven for 15 minutes.

[0065] S3. Place the prepared bismuth nanosheets@Cu mesh array face up in an ion sputtering instrument to sputter silver nanoparticles for 4 minutes to obtain a bismuth nanosheets@Cu mesh array modified with silver nanoparticles.

[0066] S4. The SERS performance of the silver nanoparticle@bismuth nanosheet@copper mesh array was tested. The prepared silver nanoparticle@bismuth nanosheet@copper mesh array substrate was immersed in Rhodamine 6G aqueous solutions of different concentrations. After 4 hours, it was removed and allowed to air dry. After drying, the Raman spectrum was measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 10 mW, and the excitation time was 1 second.

[0067] The prepared silver nanoparticles@bismuth nanosheets@copper mesh substrate were transferred to 4-aminothiophenol / ethanol solutions of different concentrations. After 4 hours, they were removed and allowed to air dry. The Raman spectra were then measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 10 mW, and the excitation time was 5 seconds.

[0068] S5. The SERS performance of the silver nanoparticle@bismuth nanosheet@copper mesh array was tested. The prepared silver nanoparticle@bismuth nanosheet@copper mesh array substrate was immersed in 4-p-aminobenzaldehyde (4-ABZ) of the same concentration for 8 hours, then removed and allowed to air dry. After drying, it was placed in a glass bottle containing shrimp meat, sealed, and then placed in an oven with the temperature set. Every so often, a sample was taken out, dried, and then the Raman spectrum was measured using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532 nm, the power was 8 mW, and the excitation time was 10 seconds.

[0069] Example 9: A method for preparing and applying an ordered silver nanoparticle@bismuth nanosheet@copper mesh array.

[0070] The difference between this embodiment and embodiment 8 is that in step S1, the diameter of the copper wire is about 60 micrometers and the spacing is about 200 micrometers.

[0071] Examples 1-4 show different deposition times, such as Figure 3 As shown, the size of the obtained bismuth nanosheet array gradually increases with increasing deposition time. When the deposition time is relatively short, such as 0.5 h ( Figure 3 a) Bismuth nanosheets with a diameter of approximately 100 nm were deposited on the surface of a Cu mesh. The spacing between adjacent bismuth nanosheets was approximately 50 nm. As the deposition time increased to 1 h ( Figure 3 (b) The size of the bismuth nanosheets deposited on the Cu mesh gradually increases, while the distance between adjacent nanosheets decreases to about 30 nm. When the deposition time is increased to 2 h ( Figure 3 c) The diameter of the bismuth nanosheets increased significantly, while the distance between adjacent nanosheets decreased to approximately 20 nm. The deposition time was further extended to 4 hours. Figure 3 d) At this point, the density of the nanosheets continues to increase, the size of a single nanosheet also increases further, and the distance between adjacent nanosheets decreases to about 10 nm.

[0072] Figure 4 The image shows a transmission electron microscope (TEM) image of bismuth nanosheets, revealing that the nanosheets are interwoven.

[0073] Figure 5 The EDS spectrum shows that the bismuth nanosheets are mainly composed of Bi and O, and the prepared bismuth nanosheets are relatively pure with no other impurities.

[0074] Figure 6 X-ray diffraction (XRD) results of the silver nanoparticle-modified bismuth nanosheets were obtained. Three distinct diffraction peaks were observed at 2θ angles of 21.4°, 27.2° and 66.3°, which were attributed to the (003), (012) and (018) crystal planes of the bismuth crystal, respectively.

[0075] Examples 4-7 show different sputtering times in the ion sputtering apparatus, such as... Figure 7 SEM images of silver nanoparticles@bismuth nanosheets@copper mesh arrays obtained by evaporating silver onto bismuth nanosheets for different times. Figure 7 The results show that when the silver sputtering time is relatively short, at 1 min, the sample still maintains the overall nanosheet array structure, but some silver nanoparticles are deposited on the nanosheets. Figure 7 b shows that when the silver sputtering time is increased to 2 min, the number of silver nanoparticles on the bismuth nanosheet surface gradually increases, and the sheet thickness increases. Figure 7 c shows that when the silver sputtering time is increased to 4 min, the bismuth nanosheets are wrapped by the silver nanosheets, and the silver nanoparticles on the surface of the nanosheets thicken. Figure 7 The data shows that when the silver sputtering time is increased to 8 min, a large number of particulate structures grow on the sample surface, making the sample surface rough.

[0076] Figure 8 The XRD results of the silver nanoparticles@bismuth nanosheets@copper mesh array are shown. Diffraction peaks of silver crystal planes were observed at 2θ angles of 38.8°, 47.6° and 65.1°, which are attributed to the (111), (200) and (220) crystal planes of silver, respectively.

[0077] When 4-aminothiophenol (4-ATP)( Figure 9 ) and Rhodamine 6G ( Figure 10 The concentration of ) was as low as 10 -11 Even at M, a certain Raman signal can still be observed on the substrate. The results indicate that the prepared substrate has good SERS activity.

[0078] Figure 11 Bismuth nanosheets@copper mesh array were evaporated with silver for 12 min at a concentration of 10. -7SERS spectra of bismuth sheets deposited at different times with M Rhodamine 6G showed that the prepared substrate had good SERS activity.

[0079] Figure 12 The immersion concentration of silver nanoparticles@bismuth nanosheets@copper mesh array substrate was 10. -3 After adding 4-p-aminobenzaldehyde (4-ABZ) to the sample, the Raman signal changes were observed when the sample was placed in a bottle containing fresh shrimp and a control bottle on a substrate. The oven temperature was set to 40℃. The Raman signal monitoring results showed that, compared to the Raman signal of the sample placed on a substrate in an empty bottle (standard sample), the Raman signal of 4-ABZ on the substrate containing fresh shrimp gradually decreased over time, and nearly disappeared after 7 hours. The main reason is that as the storage time increases, the shrimp decomposes and releases organic amines, which react with 4-ABZ, quenching its signal. The longer the storage time, the weaker the 4-ABZ signal becomes.

[0080] Figure 13 The immersion concentration of silver nanoparticles@bismuth nanosheets@copper mesh array substrate was 10. -3 After adding 4-p-aminobenzaldehyde (4-ABZ) to the sample, the Raman signal changes were observed when the sample was placed in a bottle containing fresh shrimp and a control bottle on a substrate. The oven temperature was set to 4°C. The Raman signal monitoring results showed that, compared to the Raman signal of the sample placed on a substrate in an empty bottle (standard sample), the Raman signal of 4-ABZ on the substrate containing fresh shrimp gradually decreased over time, and after 7 hours, the Raman signal nearly disappeared. The main reason is that as the storage time increases, the shrimp decomposes and releases organic amines, which react with 4-ABZ, quenching its signal. The longer the storage time, the weaker the 4-ABZ signal becomes.

[0081] Figure 14 To test the effect of a concentration of 10 on 33 randomly selected points on a silver nanoparticle@bismuth nanosheet@copper mesh array substrate. -6 The SERS spectrum of Rhodamine 6G was obtained, and the results showed that the prepared substrate had good SERS signal uniformity.

[0082] The silver nanoparticles@bismuth nanosheets@copper mesh arrays prepared in Examples 1-7 were tested and all showed good SERS activity and signal uniformity. They enabled rapid detection and identification of organic pollutants Rhodamine 6G, 4-aminobenzylthiophenol (4-ATP) and shrimp freshness, proving that they can not only detect shrimp freshness, but also have potential application value in detecting dye molecules in dyeing and printing wastewater.

[0083] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an ordered silver nanoparticle@bismuth nanosheet@copper mesh array, characterized in that, The preparation method includes substrate pretreatment, preparation of bismuth nanosheets@copper mesh array, and preparation of silver nanoparticles@bismuth nanosheets@copper mesh array. The substrate pretreatment involves ultrasonically cleaning the Cu mesh and then drying it to obtain a clean Cu mesh with a smooth surface and uniform structure. The preparation of bismuth nanosheets@copper mesh array involves preparing a bismuth nitrate solution, immersing a clean Cu mesh in the bismuth nitrate solution, and growing bismuth nanosheets by an etching reaction on the surface of the clean Cu mesh through an immersion method to obtain a bismuth nanosheets@copper mesh array. The silver nanoparticles@bismuth nanosheets@copper mesh array was prepared by sputtering silver nanoparticles onto the surface of the bismuth nanosheets@copper mesh array using an ion sputtering instrument.

2. The method for preparing the ordered silver nanoparticles@bismuth nanosheets@copper mesh array according to claim 1, characterized in that, The diameter of the copper wires in the Cu mesh is 30–60 μm, and the spacing between the copper wires is 30–200 μm.

3. The method for preparing the ordered silver nanoparticles@bismuth nanosheets@copper mesh array according to claim 1, characterized in that, The bismuth nitrate solution is prepared by dissolving solid bismuth nitrate powder in N,N-dimethylformamide solution, and its mass fraction is 0.5% to 0.9%.

4. The method of claim 1, wherein the ordered silver nanoparticle@bismuth nanosheet@ copper mesh array is prepared by the steps of: The control parameters of the ion sputtering instrument are set to a sputtering time of 1 to 8 minutes.

5. The use of an ordered silver nanoparticle@bismuth nanoplate@copper mesh array according to claim 1, wherein, The silver nanoparticles@bismuth nanosheets@copper mesh array were modified with 4-p-aminobenzaldehyde (4-ABZ) probe molecules and used as a substrate for detecting the freshness of meat-derived foods. After the substrate was brought into contact with the meat-derived food, the Raman signal of the substrate was detected by a laser Raman spectrometer, and the freshness of the meat-derived food was monitored based on the changes in the Raman signal.

6. The use of ordered silver nanoparticle@bismuth nanosheet@copper mesh arrays according to claim 5, characterized in that: After modifying 4-p-aminobenzaldehyde (4-ABZ) probe molecules with the silver nanoparticles@bismuth nanosheets@copper mesh array, the substrate was placed in the packaging environment with the meat-derived food being tested, and the Raman signal of the substrate was detected.

7. Use of the ordered silver nanoparticle@bismuth nanoplate@copper mesh array according to claim 5 or 6, characterized in that: The laser Raman spectrometer has an excitation wavelength of 532 nm, a laser power of 5–10 mW, and an excitation time of 1–10 s.

8. Use of an ordered silver nanoparticle@bismuth nanoplate@copper mesh array according to claim 1, wherein, The silver nanoparticles@bismuth nanosheets@copper mesh array was used as a substrate to detect the organic dye pollutant molecules rhodamine 6G and 4-aminophenyl thio (4-ATP) using surface-enhanced Raman scattering spectroscopy. The detection was performed using a laser Raman spectrometer with an excitation wavelength of 532 nm, a laser power of 5-10 mW, and an excitation time of 1-10 s.

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