Preparation method and application of ordered silver nanoparticle and annular nano gap array film
By filling nanospheres in the polyacrylonitrile nanopit array film and sputtering silver nanoparticles, an ordered silver nanoparticle @ ring nanogap array film was prepared, which solved the problem of signal uniformity and preparation consistency of existing SERS substrates. , realizes efficient detection of organic dyes and pesticide molecules.
Patent Information
- Application Number
- CN202411301161.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2024-12-20
AI Technical Summary
Existing SERS substrates have challenges in large-area signal uniformity and preparation consistency, especially the coupling structure based on silver nanoparticles is difficult to achieve fast, simple, controllable and uniform nanocavity construction, resulting in detection accuracy and reliability. Insufficient sex.
The polyacrylonitrile nano-pit array film is used to fill nanospheres and sputter silver nanoparticles to prepare an ordered silver nanoparticle @ ring nanogap array film to form a nanocavity structure with multiple electromagnetic field enhancement modes, and the surface is performed as a SERS substrate. Enhanced Raman scattering spectral detection.
The preparation of a silver nanoparticle @ ring nanogap array film with large area, uniform distribution and orderly morphology has been achieved, which improves the uniformity and repetition of SERS signals, and can quickly and accurately detect organic dyes and pesticide molecules, which is of great importance. Application prospects.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of analytical technology, and specifically relates to a preparation method and application of an ordered silver nanoparticle@annular nanogap array thin film SERS substrate. Background Art
[0002] With the rapid development of the domestic economy in recent decades, outstanding achievements have been made in the fields of industry and agriculture. However, water pollution caused by the development of industry and agriculture is one of the problems that need to be solved urgently. Water pollution is mainly caused by pollutants generated by human activities, including industrial pollution sources, agricultural pollution sources and domestic pollution sources. The increasingly severe water pollution has posed a major threat to human survival and safety, and has become a major obstacle to the sustainable development of human health, economy and society. Therefore, the real-time, rapid and low-concentration detection of pollutants in sewage is of great significance to protecting the water environment on which human beings depend for survival and human health and safety.
[0003] At present, common methods for detecting pollutants in water mainly include chemical analysis, electrochemical analysis and physical methods. Among them, physical methods include chromatography, mass spectrometry and spectral analysis. In recent years, the detection technology based on surface Raman scattering (SERS) effect has attracted widespread attention from researchers due to its advantages such as simple and fast operation, fast speed, no need for sample pretreatment, and fingerprint recognition characteristics. Studies have shown that the SERS enhanced signal is closely related to the nanostructure, geometry and composition of the substrate. Therefore, preparing high-quality substrates is one of the keys to realizing SERS detection technology.
[0004] In order to obtain a SERS substrate with high sensitivity and good signal uniformity, methods such as photolithography, nanoimprinting and self-assembly are used to prepare large-area, uniformly ordered noble metal nanostructure array SERS substrates. Li et al. constructed a SERS substrate of densely stacked self-assembled monolayer Au@Ag nanocubes. In this monolayer, the edges and corners of the Au@Ag nanocubes achieve a huge SERS effect by generating many hot spots. Based on this SERS substrate, low-concentration detection of 8.7×10-10M malachite green (MG) in fish pond water was achieved (Anal Bioanal Chem, 2021, 413(16): 4207-4715.), but the substrate based on the self-assembled monolayer of Au@Ag nanocubes is difficult to achieve simple preparation in large quantities. In addition, the Song team developed a silver nanoparticle (AlOOH@Ag) modified aluminum oxyhydroxide nanostructure substrate. Due to the high specific surface area of the substrate, the hot spot area assembled near the silver nanoparticles has high SERS activity. Based on this base, Congo red (CR) molecules in river water and industrial wastewater were realized, and the detection limit (LOD) was 10-9M (Applied Surface Science, 2022, 601: 154123), but AlOOH is difficult to achieve large-area structural uniformity, so it is difficult to ensure large-area uniformity of signals based on the AlOOH@Ag composite structure. In addition, Liu et al. studied the use of a plasma sensor composed of high-purity silver nanocubes (AgNCs) to detect MG molecules in aquaculture water. Liu et al. evaluated the LOD of MG molecules in the aquaculture water. This LOD is achieved thanks to the coupling between Ag nanocubes (hot spots) and the matching between the 785nm excitation wavelength for Raman measurement and the plasmon resonance peak corresponding to the monolayer silver nanocubes (Sensors and Actuators B: Chemical, 2022, 358: 131515), but the substrate based on this structure also has the problem of large-area signal instability. Chen et al. constructed a composite SERS substrate by copolymerizing molecular imprinting polymer (MIP) with Ag nanoparticles on a defective graphene layer. The SERS substrate can achieve low-concentration detection of 2.5×10-15M p-nitroaniline (PNA) in river water (Microchemical Journal, 2021, 168: 106536). Although the SERS substrate modified by this MIP can achieve low-concentration PNA detection, the MIP has the problem of poor repeatability during preparation and elution, so it is difficult to ensure the consistency of substrate preparation.
[0005] The currently developed SERS substrate construction technology is mainly based on the coupling between silver nanoparticles. In recent years, the SERS substrate based on precious metal nanocavities has gradually attracted the attention of researchers. Precious metal nanocavities have multiple electromagnetic field coupling modes and can stimulate stronger SERS effects. However, the nanocavity construction technology reported so far is mostly based on electron beam etching and other technologies, which are relatively expensive. Therefore, it is of great significance to develop a mature, stable, fast and simple method for preparing a morphology-controlled and uniform precious metal nanocavity SERS substrate. Summary of the invention
[0006] In order to solve the problems existing in the prior art, the present invention provides a method for preparing an ordered silver nanoparticle@annular nanogap array film and its application, so as to achieve the invention purpose of preparing a fast, simple, morphology-controllable and uniform silver nanoparticle-modified annular nanogap SERS substrate.
[0007] To solve the above technical problems, one of the purposes of the present invention is to provide a method for preparing an ordered silver nanoparticle @ annular nanogap array film, characterized in that the preparation method comprises preparing a polyacrylonitrile (PAN) nano-pit array film, preparing a PAN pit array film filled with nanospheres, and sputtering silver nanoparticles to obtain an ordered silver nanoparticle @ annular nanogap array film;
[0008] The polyacrylonitrile (PAN) nano-pit array film is prepared by uniformly dispersing a certain mass fraction of PAN (polyacrylonitrile) solution on a silicon wafer template having a regular nano-pillar array structure, and then peeling the silicon wafer template after drying to obtain a PAN film having an ordered nano-pit array structure on one side;
[0009] The method for preparing the PAN nano-pit array film filled with nano-spheres comprises the following steps:
[0010] Step 1: Ultrasonically disperse the spherical nanoparticles uniformly in deionized water to obtain a nanosphere dispersion solution with a certain mass fraction;
[0011] Step 2: placing the PAN nano-pit array film in the nano-ball dispersion solution, and after the solution evaporates, the nano-balls are filled into the PAN nano-pits, thereby preparing a PAN pit array film filled with nano-balls.
[0012] The silver nanoparticles are sputtered by using an ion sputtering device to sputter the silver nanoparticles on the surface of the PAN pit array film filled with nanospheres, so as to obtain an ordered silver nanoparticle@annular nanogap array film.
[0013] Preferably, the diameter of the nano-pit is 300nm to 2700nm.
[0014] Preferably, in step 1, the spherical nanoparticles are silicon dioxide (SiO2) spherical nanoparticles.
[0015] Preferably, in step 1, the spherical nanoparticles may also be polystyrene (PS) spherical nanoparticles.
[0016] Preferably, in step 1, the mass concentration of the nanosphere dispersion solution is 0.25-0.75%.
[0017] Preferably, the sputtering time of the silver nanoparticles is 1 to 12 minutes.
[0018] Preferably, the mass fraction of the PAN (polyacrylonitrile) solution is 5% to 12%.
[0019] Preferably, in step 2, the PAN nano-pit array film is placed in the nanosphere dispersion solution at an inclined angle of 75°.
[0020] The second object of the present invention is to provide an application of the ordered silver nanoparticles@annular nanogap array film prepared by the above method, wherein the application is to use the prepared ordered silver nanoparticles@annular nanogap array film as a SERS substrate to perform surface enhanced Raman scattering spectral detection on organic dye pollutant molecules rhodamine 6G (R6G) and crystal violet (CV) and the pesticide molecule thiram.
[0021] Furthermore, the surface enhanced Raman scattering spectral detection uses organic dye pollutants R6G and CV and the pesticide molecule thiram as detection molecules, and an ordered silver nanoparticle@annular nanogap array film that has been immersed in an aqueous solution of R6G, CV and an ethanol solution of the pesticide molecule thiram and dried as a substrate, and Raman detection is performed using a laser Raman spectrometer.
[0022] In a further embodiment, the excitation wavelength of the laser Raman spectrometer is 532 nm and 785 nm, the laser power is 5-10 mW, and the excitation time is 1-10 s.
[0023] Due to the adoption of the above technical solution, the technical effects achieved by the present invention are:
[0024] 1. A method for preparing an ordered silver nanoparticle @ annular nanogap array film provided by the present invention is used to fill silica balls or PS nanoballs in ordered PAN nanopits, and then sputter silver nanoparticles to prepare a large-area, uniformly distributed, and orderly morphological silver nanoparticle @ annular nanogap array film, thereby obtaining an ordered annular silver nanoparticle cavity array substrate. The method is simple to operate and low in cost. The morphology of the silver nanoparticle @ annular nanogap array is controlled by adjusting the arrangement of PAN nanopits and the diameter of the pits, the size of the silica balls or PS nanoballs, and the sputtering time of the silver nanoparticles, thereby obtaining a uniform and ordered annular silver nanoparticle cavity array substrate.
[0025] 2. The ordered silver nanoparticles@annular nanogap array thin film substrate prepared by this method not only combines the high SERS activity of silver nanoparticles, but also the nanospheres and pits form a large-area ordered annular array that can load more uniform and ordered silver nanoparticles. The annular nanogap constructs a nanocavity structure with multiple electromagnetic field enhancement modes, which can excite a stronger local electromagnetic field and is conducive to generating a stronger SERS signal. At the same time, the large-area silver nanoparticles@annular nanogap array has a very uniform morphology, which ensures the good SERS signal uniformity and repeatability of the substrate.
[0026] 3. The ordered silver nanoparticles@annular nanogap arrays prepared by this method have potential application prospects in the fields of chemical analysis, pollutant detection, biosensors, etc. based on SERS technology. Using it as a SERS substrate, rapid detection and identification of organic pollutants R6G and CV and the pesticide molecule thiram are achieved, which is of great significance in realizing rapid trace detection of pollutants in wastewater using the SERS effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 Schematic diagram of the preparation process of silver nanoparticles@annular nanogap arrays;
[0028] Figure 2 Scanning electron microscope (SEM) photos of PAN nano-pit array films of different sizes and morphologies: (a) hexagonal nano-pit array with a pit diameter of 300nm; (b) tetragonal pit array with a pit diameter of 340nm; (c) hexagonal nano-pit array with a pit diameter of 2700nm.
[0029] Figure 3These are SEM photos of the hexagonal nano-pit film filled with silica nanospheres. Figure (ab) shows the hexagonal pit array film without silica ball filling, with a pit diameter of 300nm; Figure (cd) shows the film filled with SiO2 nanospheres with a diameter of 120nm; Figure (ef) shows the film filled with SiO2 nanospheres with a diameter of 200nm; Figure (hi) shows the film filled with SiO2 nanospheres with a diameter of 300nm.
[0030] Figure 4 These are SEM photos of the tetragonal nano-pit film filled with silica nanospheres. Figures (ab) are tetragonal pit array films that are not filled with silica balls, with a pit diameter of 340nm; Figures (cd) are tetragonal pits filled with SiO2 balls with a size of 200nm; and Figure (ef) is filled with SiO2 nanospheres with a diameter of 300nm.
[0031] Figure 5 These are SEM photos of the hexagonal PAN pit film after filling with PS balls. Figure (ab) is the hexagonal pit array film without PS ball filling, with a pit diameter of 300nm; Figure (cd) is filled with PS nanospheres with a diameter of 150nm; Figure (ef) is filled with PS balls with a diameter of 200nm; Figure (hi) is filled with PS balls with a diameter of 250nm.
[0032] Figure 6 These are SEM photos of the tetragonal PAN pit film filled with PS balls. Figure (ab) shows the tetragonal pit array film without PS ball filling, with a pit diameter of 340nm; Figure (cd) shows the tetragonal pits filled with PS balls of 150nm in size; Figure (ef) shows the filled PS balls with a diameter of 200nm; Figure (hi) shows the filled PS balls with a diameter of 250nm; Figure (jk) shows the filled PS balls with a diameter of 300nm.
[0033] Figure 7 These are SEM photos of the hexagonal PAN pit film after being filled with PS balls. Figure (ab) shows the hexagonal pit array film without PS ball filling, and the pit size is about 2700nm; Figure (cd) shows the hexagonal pit filled with PS balls with a size of 2000nm.
[0034] Figure 8 These are SEM photographs of the thin films obtained by filling SiO2 nanospheres (diameter 120nm) with PAN hexagonal pit arrays and then sputtering silver nanoparticles for different times (pit size is about 300nm). Figure (ab) sputtering time 0min; Figure (cd) sputtering time 1min; Figure (ef) sputtering time 2min; Figure (hi) sputtering time 4min; Figure (jk) sputtering time 8min.
[0035] Fig. 9These are SEM photos of the thin film obtained by filling the PAN hexagonal pit array with SiO2 nanospheres (diameter 200nm) and then sputtering silver nanoparticles for different times. The size of the pit is about 300nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0036] Fig.10 These are SEM photos of the film obtained by filling the PAN hexagonal pit array with SiO2 nanospheres (diameter 300nm) and then sputtering silver nanoparticles for different times. The pit size is about 300nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0037] Fig.11 These are SEM photos of the film obtained by filling the PAN square pit array with SiO2 nanospheres (diameter 200nm) and then sputtering silver nanoparticles for different times. The size of the pit is about 340nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0038] Fig.12 These are SEM photos of the film obtained by filling the PAN square pit array with SiO2 nanospheres (diameter 300nm) and then sputtering silver nanoparticles for different times. The size of the pit is about 340nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0039] Fig.13 These are SEM photos of the film obtained by filling the PAN hexagonal pit array with PS nanospheres (diameter 250nm) and then sputtering silver nanoparticles for different times. The size of the pit is about 300nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0040] Fig.14These are SEM photos of the film obtained by filling the PAN square pit array with PS nanospheres (diameter 250nm) and then sputtering silver nanoparticles for different times. The size of the pit is about 340nm. Figure (ab) has a sputtering time of 0min; Figure (cd) has a sputtering time of 1min; Figure (ef) has a sputtering time of 2min; Figure (hi) has a sputtering time of 4min; and Figure (jk) has a sputtering time of 8min.
[0041] Fig.15 These are SEM photos of the film obtained by filling the PAN hexagonal pit array with PS nanospheres (diameter 2000nm) and then sputtering silver nanoparticles for different times. The diameter of the pit is about 2700nm. The sputtering time in Figures (ab) is 2 minutes; the sputtering time in Figure (cd) is 4 minutes; the sputtering time in Figure (ef) is 8 minutes; and the sputtering time in Figure (gh) is 12 minutes.
[0042] Fig.16 EDS spectrum of PAN hexagonal pit array film filled with silica spheres;
[0043] Fig.17 EDS spectrum of the silver nanoparticle@annular nanogap array film filled with silica nanospheres;
[0044] Fig.18 This is the EDS spectrum of the silver nanoparticle@annular nanogap array film filled with PS nanospheres;
[0045] Fig.19 X-ray diffraction spectra of PAN nanopit array film, silica-filled nanopit array film, and silver nanoparticle@annular nanogap array film.
[0046] Fig. 20 SERS spectra of optimized silver nanoparticles@annular nanogap array film to different concentrations of rhodamine R6G;
[0047] Fig.21 SERS spectra of the optimized silver nanoparticles@annular nanogap array film to different concentrations of crystal violet (CV);
[0048] Fig. 22 To optimize the SERS spectra of silver nanoparticles@annular nanogap array film to different concentrations of pesticide molecule thiram;
[0049] Fig.23 Silver nanoparticles@annular nanogap array film adsorbed with 10 -7 mol / L4-ATP molecules on a large area (50×50μm 2 ) The spectral imaging was performed at 1078 cm -1Characterization picture of Raman signal intensity at ;
[0050] Fig.24 40 points were randomly selected on the silver nanoparticles@annular nanogap array film to test the effect of concentration of 10 -7 SERS spectrum of 4-aminobenzenethiophenol of M;
[0051] Fig.25 40 Raman spectra obtained for silver nanoparticles@annular nanogap array film at 1078 cm -1 The intensity of the characteristic peaks at . DETAILED DESCRIPTION
[0052] The following is a detailed description of the embodiments and the attached Figure 1-25 , further illustrating the present invention.
[0053] Example 1 Preparation method and application of an ordered silver nanoparticle@annular nanogap array thin film array
[0054] S1. 0.25 mL of polyacrylonitrile (PAN) solution was evenly dripped onto the silicon wafer template with a regular and ordered nanocolumn array structure, and then placed in a 70°C oven for drying for 30 min. After drying, the solidified PAN nano-pit film was peeled off from the template and transferred onto the silicon wafer with the side having the hexagonal nano-pit array facing upward to obtain a PAN film with an ordered nano-pit array structure on one side; Figure 2 As shown in a, scanning electron microscopy (SEM) analysis shows that the nanocolumn array on the film has a regular shape and uniform structure, and the diameter of the nanopits is about 300 nm.
[0055] The preparation method of the PAN solution is as follows: dissolving polyacrylonitrile powder in N,N-dimethylformamide solution, stirring in an oil bath at 60° C. for 30 minutes, and obtaining a PAN solution with a mass fraction of 5%.
[0056] S2. The prepared PAN dimple film is attached to a glass slide and tilted at 75°, immersed in a 0.5% by mass silica sphere uniformly dispersed solution, and dried in an oven at 80°C to obtain a PAN nano-dimpled film filled with silica nanospheres.
[0057] S3. Place the composite film with its front side facing upward in an ion sputtering apparatus to sputter silver nanoparticles for 1 min to obtain a silver nanoparticle@annular nanogap array film.
[0058] S4. The SERS performance of the silver nanoparticles@annular nanogap array film was tested. The prepared silver nanoparticles@annular nanogap array film SERS substrate was immersed in different concentrations of rhodamine R6G aqueous solution, taken out after 4 hours and allowed to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532nm, the power was 5mW, and the excitation time was 2 seconds.
[0059] The prepared silver nanoparticles@annular nanogap array film substrate was transferred to ethanol solutions of crystal violet CV of different concentrations, and taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 1 milliwatt, and the excitation time was 2 seconds.
[0060] The prepared silver nanoparticles@annular nanogap array film substrate was transferred to ethanol solutions of pesticide molecule thiram of different concentrations, and taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 5 milliwatts, and the excitation time was 2 seconds.
[0061] Example 2 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0062] The difference between this embodiment and embodiment 1 is that the pit size in step S1 is 340 nm.
[0063] Example 3 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0064] The difference between this embodiment and embodiment 1 is that the pit size in step S1 is 2700 nm.
[0065] Example 4 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0066] S1. Evenly drip 0.25 mL of PAN (polyacrylonitrile) solution onto a silicon wafer template having a regular and ordered nanopillar array structure, and then place the film in a 70°C oven for drying for 30 min. After drying, peel off the cured PAN film from the template and transfer the film onto the silicon wafer with the nanopit array facing upward to obtain a PAN film having a hexagonally arranged ordered nanopit array structure on one side.
[0067] The preparation method of the PAN solution is as follows: dissolving polyacrylonitrile powder in N,N-dimethylformamide solution, stirring in an oil bath at 60° C. for 30 minutes, and obtaining a PAN solution with a mass fraction of 8%.
[0068] S2. The prepared PAN pit film is attached to a glass slide and tilted at 75°. It is immersed in a uniformly dispersed solution of silica balls (diameter 120 nm) with a mass fraction of 0.5%. The film is dried in an oven at 80°C to obtain a PAN nano-pit array film filled with silica balls.
[0069] S3. Place the composite film with the front side facing upward in an ion sputtering apparatus to sputter silver nanoparticles for 1 min to obtain a silver nanoparticle@silica ball@PAN pit film.
[0070] S4. The SERS performance of the silver nanoparticles@annular nanogap array film was tested. The prepared silver nanoparticles@annular nanogap array film was immersed in different concentrations of rhodamine R6G aqueous solution, taken out after 4 hours to let it dry naturally, and then tested the Raman spectrum using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer is 532nm, the power is 5mW, and the excitation time is 2 seconds.
[0071] The prepared silver nanoparticles@annular nanogap array film was transferred to ethanol solutions of crystal violet CV of different concentrations, and taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 1 milliwatt, and the excitation time was 2 seconds.
[0072] The prepared silver nanoparticles@annular nanogap array film was transferred to ethanol solutions of pesticide molecule thiram with different concentrations, and then taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 5 milliwatts, and the excitation time was 2 seconds.
[0073] Example 5 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0074] The difference between this embodiment and embodiment 4 is that the size of the silica spheres in step S2 is 200 nm.
[0075] Example 6 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0076] The difference between this embodiment and embodiment 4 is that the size of the silica spheres in step S2 is 300 nm.
[0077] Example 7 Preparation method and application of ordered silver-silver nanoparticle@annular nanogap array film
[0078] S1. Evenly drip 0.25 mL of PAN (polyacrylonitrile) solution onto the silicon wafer template with a regular and ordered nanopillar array structure, and then put it into an oven at 70°C for drying for 30 min. After drying, peel off the solidified PAN film from the template, and transfer the side with the nanopit array facing up to the silicon wafer to obtain a PAN film with an ordered nanopit array structure on one side.
[0079] The preparation method of the PAN solution is as follows: dissolving polyacrylonitrile powder in N,N-dimethylformamide solution, stirring in a water bath at 60° C. for 30 minutes, and obtaining a PAN solution with a mass fraction of 12%.
[0080] S2. The prepared PAN pit film is attached to a glass slide and tilted at 75°, immersed in a uniformly dispersed solution of silica balls with a mass fraction of 0.5%, and dried in an oven at 80°C to obtain a vertically falling silica ball@PAN pit film.
[0081] S3. Place the composite film with the front side facing upward in an ion sputtering apparatus to sputter silver nanoparticles for 1 min to obtain a silver nanoparticle@silica ball@PAN pit film.
[0082] S4. The SERS performance of the silver nanoparticles@annular nanogap array film was tested. The prepared silver nanoparticles@annular nanogap array film was immersed in different concentrations of rhodamine 6G aqueous solution, taken out after 4 hours to let it dry naturally, and then tested the Raman spectrum using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer is 532nm, the power is 5mW, and the excitation time is 2 seconds.
[0083] The prepared silver nanoparticles@annular nanogap array film was transferred to ethanol solutions of crystal violet CV of different concentrations, and taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 1 milliwatt, and the excitation time was 2 seconds.
[0084] The prepared silver nanoparticles@annular nanogap array film was transferred to ethanol solutions of pesticide molecule thiram with different concentrations, and then taken out after 4 hours to allow it to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 5 milliwatts, and the excitation time was 2 seconds.
[0085] Example 8 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0086] The difference between this embodiment and embodiment 7 is that the silver sputtering time in step S3 is 2 minutes.
[0087] Example 9 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0088] The difference between this embodiment and embodiment 7 is that the silver sputtering time in step S3 is 4 minutes.
[0089] Example 10 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0090] The difference between this embodiment and embodiment 7 is that the silver sputtering time in step S3 is 8 minutes.
[0091] Example 11 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0092] S1. Evenly drip 0.25 mL of PAN (polyacrylonitrile) solution onto the silicon wafer template with a regular and ordered nanopillar array structure, and then put it into an oven at 70°C for drying for 30 min. After drying, peel off the solidified PAN film from the template, and transfer the side with the nanopit array facing up to the silicon wafer to obtain a PAN film with an ordered nanopit array structure on one side.
[0093] The preparation method of the PAN solution is to dissolve polyacrylonitrile powder in N,N-dimethylformamide solution, and stir in a water bath at 60° C. for 30 minutes to obtain a PAN solution with a mass fraction of 10%.
[0094] S2. The prepared PAN pit film is attached to a glass slide and tilted at 75°. It is immersed in a uniformly dispersed solution of PS nanospheres (diameter 150 nm) with a mass fraction of 0.5% mol / L, and then dried in an oven at 80°C to obtain a PAN nano pit film filled with PS nanospheres.
[0095] S3. Place the composite film with the front side facing upward in an ion sputtering apparatus to sputter silver nanoparticles for 1 min to obtain a silver nanoparticle@PS ball@PAN pit film.
[0096] S4. The SERS performance of the silver nanoparticles @PS nanospheres @PAN nano-pit film was tested. The prepared silver nanoparticles @PS nanospheres @PAN nano-pit film was immersed in different concentrations of rhodamine R6G aqueous solution, taken out after 4 hours and allowed to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532nm, the power was 5 milliwatts, and the excitation time was 2 seconds.
[0097] The prepared silver nanoparticles@PS nanospheres@PAN nanopitted films were transferred to ethanol solutions of crystal violet CV of different concentrations, taken out after 4 hours to allow them to dry naturally, and then tested the Raman spectrum using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 532nm, the power was 1 milliwatt, and the excitation time was 2 seconds.
[0098] The prepared silver nanoparticles@PS nanospheres@PAN nano-pit film was transferred to ethanol solutions of different concentrations of the pesticide molecule thiram, and taken out after 4 hours to dry naturally. After drying, the Raman spectrum was tested using a laser Raman spectrometer. The excitation wavelength of the laser Raman spectrometer was 785nm, the power was 5 milliwatts, and the excitation time was 2 seconds.
[0099] The difference between this embodiment and embodiments 1-4 is that the size of the PS spheres in step S2 is 150 nm.
[0100] Example 12 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0101] The difference between this embodiment and embodiment 11 is that the size of the PS spheres in step S2 is 200 nm.
[0102] Example 13 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0103] The difference between this embodiment and embodiment 11 is that the size of the PS spheres in step S2 is 250 nm.
[0104] Example 14 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0105] The difference between this embodiment and embodiment 11 is that the size of the PS spheres in step S2 is 300 nm.
[0106] Example 15 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0107] The difference between this embodiment and embodiment 11 is that the size of the PS spheres in step S2 is 2000 nm.
[0108] Example 16 Preparation method and application of an ordered silver nanoparticle@annular nanogap array film
[0109] The difference between this embodiment and embodiments 1-15 is that the PAN pit array in step S1 is arranged in a square array.
[0110] Example 1-6 Controlling the size and arrangement of the pit array and the size of the spheres will affect the morphology of the substrate and the SERS performance. When the sphere size is small, the annular voids on the surface of the PAN pits are larger. As the size of the spheres increases, the size of the voids on the surface of the PAN film continues to shrink, forming an ordered sphere structure on the surface of the PAN pits. Figure 3 and 4 As shown in FIG. 1 , as the size of the silica sphere increases, the size of the annular gaps in the obtained pit array gradually decreases. The sizes of the PS spheres in Examples 11-15 are different. Figure 5 , 6 Same as shown in 7 Figure 3 and Figure 4 Similar to the rule, for the same size of pit array film, as the size of PS ball (150, 200, 250, 300 nm) increases, the pit array gaps gradually decrease.
[0111] In Examples 7-10, when the silver nanoparticle sputtering time is relatively short, i.e., 1 min ( Figure 8 c), the pit array film with a diameter of about 300nm is filled with 120nm silica spheres, and the surface of the composite substrate is sputtered with silver nanoparticles. When the sputtering time is 1min, it can be observed that the substrate surface has signs of thickening in the microscopic morphology, and as the sputtering time of silver nanoparticles increases, such as 2min ( Figure 8 e) 4min( Figure 8 h)、8min( Figure 8 j), it can be observed from the microscopic morphology that the increase of silver nanoparticle sputtering time will make the film surface thicker and the pore size decrease accordingly, which is most obvious at 8 min, and it can be seen that the pores are completely blocked by the sputtered silver nanoparticles. Figure 9-12 and Figure 8 When the filled balls are PS nanospheres, the size of the annular nanogap gradually decreases and the number of silver nanoparticles attached to the surface gradually increases with the increase of the PS ball diameter and the silver sputtering time ( Figure 13-14 ). Fig.15 The size of the hexagonal pits is 2700nm, while the size of the PS balls is 2000nm. The silver nanoparticles are sputtered on the surface for 2, 4, 8 and 12min respectively. From the microscopic morphology characterization pictures, it can be seen that the silver nanoparticles have been sputtered for a long time, the particles are accumulated more and larger, and the pores are completely blocked. The number of silver nanoparticles attached to the surface gradually increases and the size of the attached particles also gradually increases.
[0112] Fig.16 EDS spectrum of PAN pit film filled with silica spheres. Fig.17This is the EDS spectrum of the silver nanoparticle@annular nanogap array film obtained by sputtering silver on a PAN pit film filled with silica balls. Fig.16 It shows that the PAN pit film filled with silica spheres is mainly composed of Si and C, and the prepared sample is relatively pure without other impurities. Fig.17 This indicates that the silver nanoparticles@annular nanogap array film obtained by sputtering silver on the PAN pit film filled with silica balls is mainly composed of C, Si and Ag. Fig.18 The results show that the silver nanoparticles@annular nanogap array film obtained by sputtering silver on the PAN pit film filled with PS balls is mainly composed of C and Ag, the sample is relatively pure, and no other unnecessary impurities appear.
[0113] Fig.19 The X-ray diffraction spectrum results of different films. From the spectrum of the nano-pit array film filled with silicon dioxide, it can be seen that there are two peaks, at 2θ=10°~20° and 2θ=20°~30°, respectively. The former peak has an obvious crystal diffraction peak, but the second peak is dome-shaped and no obvious crystal diffraction peak appears. That is, the XRD curve of the sample does not show obvious characteristic crystal diffraction peaks, but there is an amorphous dispersion peak of silicon dioxide, and the intensity of this peak is still relatively small, which indicates that the component of the sample is disordered amorphous silicon dioxide. After sputtering silver, the silver nanoparticles @ annular nanogap array film sample was observed to have four obvious diffraction peaks at 38.95°, 45.25°, 65.4°, and 78.1°, which belong to the characteristic peaks of silver. It shows that the prepared substrate is mainly composed of Si, O, and Ag, which further proves the successful preparation of the silver nanoparticles @ annular nanogap array film.
[0114] When R6G( Fig. 20 ) and CV( Fig.21 ) and the pesticide molecule Thiram ( Fig. 22 ) concentrations were as low as 10 -13 M, 10 -9 M and 10 -8 When M, the substrate can still observe certain Raman characteristic peak signals of the analyte. The results show that the prepared substrate has good SERS activity.
[0115] Fig.23 For adsorption of 10 -7 mol / L4-ATP substrate, randomly selected 50×50μm 2 The uniformity of the substrate signal was further evaluated by SERS mapping. -1 The mapping image generated by the SERS intensity of the characteristic peak at Fig.23As shown, a single pixel represents the intensity of the Raman signal at the corresponding position, verifying that the prepared silver nanoparticle@annular nanogap array film substrate has good SERS uniformity.
[0116] Fig.24 and 25 The results were obtained by randomly selecting 40 points on the silver nanoparticle@annular nanogap array film substrate to test the effect of concentration of 10 -7 The SERS spectrum of 4-aminobenzenethiophenol of M was obtained. The results showed that the prepared substrate had good SERS signal sensitivity and signal uniformity.
[0117] The silver nanoparticle@annular nanogap array films prepared in Examples 1-15 were tested and all showed good SERS activity and signal uniformity, achieving rapid detection and identification of organic pollutants R6G and CV and the pesticide molecule thiram, demonstrating its potential application value in detecting dye molecules in printing and dyeing wastewater.
[0118] Unless otherwise specified, the ratios and percentages described in the present invention are all weight ratios and weight percentages; and the raw materials are all commercially available.
[0119] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing an ordered silver nanoparticle@annular nanogap array film, characterized in that: The preparation method comprises preparing a polyacrylonitrile (PAN) nano-pit array film, preparing a PAN pit array film filled with nanospheres, and sputtering silver nanoparticles to obtain an ordered silver nanoparticle@annular nanogap array film; The polyacrylonitrile (PAN) nano-pit array film is prepared by uniformly dispersing a certain mass fraction of PAN (polyacrylonitrile) solution on a silicon wafer template having a regular nano-pillar array structure, and then peeling the silicon wafer template after drying to obtain a PAN film having an ordered nano-pit array structure on one side; The method for preparing the PAN nano-pit array film filled with nano-spheres comprises the following steps: Step 1: Ultrasonically disperse the spherical nanoparticles uniformly in deionized water to obtain a nanosphere dispersion solution with a certain mass fraction; Step 2: placing the PAN nano-pit array film in the nano-ball dispersion solution, and after the solution evaporates, the nano-balls are filled into the PAN nano-pits, thereby preparing a PAN pit array film filled with nano-balls. The silver nanoparticles are sputtered by using an ion sputtering device to sputter the silver nanoparticles on the surface of the PAN pit array film filled with nanospheres, so as to obtain an ordered silver nanoparticle@annular nanogap array film.
2. The method for preparing the ordered silver nanoparticle@annular nanogap array film according to claim 1, characterized in that: The diameter of the nano pit is 300-2700 nm.
3. The method for preparing the ordered silver nanoparticle@annular nanogap array film according to claim 1, characterized in that: In step 1, the spherical nanoparticles are silicon dioxide (SiO2) spherical nanoparticles.
4. The method for preparing the ordered silver nanoparticle@annular nanogap array thin film according to claim 1, characterized in that: In step 1, the spherical nanoparticles may also be polystyrene (PS) spherical nanoparticles.
5. The method for preparing the ordered silver nanoparticle@annular nanogap array film according to claim 1, characterized in that: In step 1, the mass concentration of the nanosphere dispersion solution is 0.25-0.75%.
6. The method for preparing the ordered silver nanoparticle@annular nanogap array thin film according to claim 1, characterized in that: The time for sputtering the silver nanoparticles is 1 to 12 minutes.
7. The method for preparing the ordered silver nanoparticle@annular nanogap array film according to claim 1, characterized in that: The mass fraction of the PAN (polyacrylonitrile) solution is 5-12%.
8. The method for preparing the ordered silver nanoparticle@annular nanogap array thin film according to claim 1, characterized in that: In step 2, the PAN nano-pit array film is placed in the nanosphere dispersion solution at an inclined angle of 75°.
9. Application of the ordered silver nanoparticle@annular nanogap array film prepared by the preparation method of claim 1, characterized in that: The silver nanoparticle@annular nanogap array film is used as a substrate to perform surface enhanced Raman scattering spectroscopy detection on organic dye pollutant molecules rhodamine 6G and crystal violet (CV) and pesticide molecule thiram; the detection uses a laser Raman spectrometer with an excitation wavelength of 532nm and 785nm, a laser power of 5-10mW, and an excitation time of 1-10s.