Plasmon-enhanced nanocone structures, their preparation methods and applications

Abstract

This invention proposes a plasmonic-enhanced nanocone structure for detecting micro / nanoplastics and other contaminants, its preparation method, and its applications. The plasmonic-enhanced nanocone structure exhibits a gold-silver nanoparticle bimetallic hollow nanostructure (BHNC-Au / Ag). This structure can achieve a density as high as 1.1 × 10⁻⁶. 8 Physical enhancements and self-constructed enrichment of target stratified analytes for size-matched hotspot regions were employed. Intrastructural stratified hotspots (DSHSs, DVHSs, and LHSs) were identified to promote the enrichment of target contaminants in optimal hotspot regions, thereby enhancing the enrichment of micro / nanoplastics smaller than 5 micrometers (down to 10 μm) at typical geometric scales. ‑8 g / L), small molecules (down to 10 g / L) ‑13 M) and SARS-CoV-2S protein (down to 10) ‑9 M) for high-sensitivity detection. The technical solution provided by this invention offers a practical solution for the trace detection of layered micro / nano plastics and other mixed water contaminants.

Description

Technical Field

[0001] This invention relates to the field of surface-enhanced Raman scattering detection technology, and in particular to a plasmonic-enhanced nanocone structure, which is structurally a three-dimensional gold-silver hollow nanocone structure. Background Technology

[0002] In recent years, plastic exposure has become one of the most pressing safety risks facing modern human society, impacting environmental health, ecosystem stability, and daily life. Among these risks, micro- and nano-plastics, due to their unique properties and widespread distribution, have become a focus of research and regulation. Micro- and nano-plastics possess layered geometric dimensions ranging from nanometers to micrometers, along with extremely large specific volume and surface area, making them ideal carriers of harmful substances such as viruses and bacteria, thus posing a potential threat to human health and ecological stability. More importantly, in diverse aquatic environments, these plastic residues often exhibit complex particle size distribution characteristics, and their chemical stability and physical inertness significantly increase the difficulty of rapid and effective detection.

[0003] Against this backdrop, the introduction of plasmonic nanostructures has provided a new pathway for surface-enhanced Raman scattering (SERS) technology. SERS technology leverages the localized surface plasmon resonance effect generated by plasmonic nanostructures to significantly enhance the Raman scattering signal of the analyte. Furthermore, in recent years, the development of three-dimensional (3D) plasmonic nanostructures has further improved detection capabilities due to their high-density three-dimensional hotspot distribution and flexibility in spectral manipulation. These 3D structures have demonstrated powerful detection capabilities in solar vapor generation, water purification, and plasmonic optical monitoring. However, when dealing with large-scale, layered targets, such as micro / nanoplastics in water, detection using plasmonic SERS still faces numerous challenges. The wide particle size range of micro / nanoplastics often leads to spatial inconsistencies when matching with hotspot regions, significantly limiting the sensitivity and accuracy of detection. The patent with publication number CN2020104136608 provides a gold-silver nanocone array with bulk enhanced Raman scattering effect. The gold-silver nanocone array is prepared by multiple anodic oxidation and wet etching, followed by gold and silver film coating. However, the detection range of the gold-silver nanocone array structure for target identification is narrow and cannot achieve high detection accuracy, which limits the efficient identification and accurate analysis of complex targets of multiple sizes and levels. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a plasmonic-enhanced nanocone structure, which structurally exhibits a three-dimensional gold-silver hollow nanocone structure. The plasmonic-enhanced nanocone structure is fabricated by depositing a gold film on a template with a V-shaped nanopore structure, removing the template by etching to obtain a V-shaped nanocone structure with the gold film deposited, and then depositing a silver film on the V-shaped nanocone structure with the gold film deposited.

[0005] The thickness of the gold film in the plasmon-enhanced nanocone structure is 200-300 nm, and the thickness of the silver film is 20-40 nm; the pore size of the plasmon-enhanced nanocone structure is 10-30 nm.

[0006] Preferably, the thickness of the gold film in the plasmon-enhanced nanocone structure is 250 nm, and the thickness of the silver film is 30 nm; the pore size of the plasmon-enhanced nanocone structure is 20 nm.

[0007] The gold film has a thickness of 200-300 nm, and the silver film has a thickness of 20-40 nm; the pore size of the nanocone structure is 10-30 nm. The pores refer to the porous structure on the surface of the nanocone.

[0008] Preferably, the template with the V-shaped nanopore structure is selected from one of the following: anodized aluminum oxide template, porous silicon template, or titanium oxide nanotube array template with the V-shaped nanopore structure; the maximum pore diameter of the V-shaped nanopore is 400~500 nm and the pore depth is 800~1000 nm.

[0009] Preferably, the gold film is prepared by electron beam vapor deposition; the silver film is prepared by magnetron sputtering.

[0010] Preferably, the thickness of the gold film is 250 nm, the thickness of the silver film is 30 nm, and the pore size of the nanocone structure is 20 nm.

[0011] This invention also provides a method for preparing plasmonic-enhanced nanocone structures, the preparation steps of which are as follows:

[0012] Step 1: Clean and pre-treat a template with a V-shaped nanoporous structure; after drying, deposit a gold film on the template with the V-shaped nanoporous structure using electron beam vapor deposition.

[0013] Step 2: The product obtained in Step 1 is subjected to etching and demolding treatment to obtain a cone-shaped gold nanostructure;

[0014] Step 3: Deposit a silver film on the surface of the cone-shaped gold nanostructure obtained in Step 2 using magnetron sputtering technology.

[0015] Preferably, the template with V-shaped nanopore structure in step 1 is one of anodized aluminum oxide template, porous silicon template or titanium oxide nanotube array template with V-shaped nanopore structure; the anodized aluminum oxide template with V-shaped nanopore structure contains periodically arranged V-shaped nanopores, the maximum pore diameter of the V-shaped nanopores is 400~500 nm and the pore depth is 800~1000 nm.

[0016] Preferably, the conditions for electron beam vapor deposition in step 1 are as follows: the template and gold target with V-shaped nanopore structure are placed in the vacuum deposition chamber of the electron beam vapor deposition instrument, and the gas pressure in the vacuum deposition chamber is adjusted to 5 × 10⁻⁶. -4 ~ 9×10 - 4 Pa deposited 200-300 nm gold films on V-type AAO templates at a rate of 20-40 nm / min.

[0017] Preferably, the conditions for magnetron sputtering in step 3 are as follows: the conical gold nanostructure and silver target obtained in step 2 are placed in the vacuum deposition chamber of the magnetron sputtering instrument, an inert gas is introduced, and the gas pressure in the vacuum deposition chamber is adjusted to 5 × 10⁻⁶. -4 ~ 9×10 -4 Pa, with sputtering power set to 40~60 W, coating time to 10~30 min, and silver film thickness to 20~40 nm.

[0018] An application of the plasmon-enhanced nanocone structure obtained according to the technical solution provided by the present invention is to apply the plasmon-enhanced nanocone structure to the SERS detection of layered micro- and nano-scale pollutants.

[0019] Preferably, the plasmon-enhanced nanocone structure is applied to the SERS detection of drug molecules, dye molecules, virus particles, and micro / nanoplastics contaminants.

[0020] Beneficial effects

[0021] This invention proposes a plasmonic-enhanced nanocone structure for detecting micro / nanoplastics and other contaminants, its preparation method, and its applications. The plasmonic-enhanced nanocone structure is structurally a gold-silver nanoparticle bimetallic hollow nanostructure (BHNC-Au / Ag). This plasmonic-enhanced nanocone structure integrates high-density surface and volume hotspots into a single structure. Through the V-shaped close-packed bimetallic nanoparticles with abundant nanopores in both the lateral and longitudinal regions, hierarchical hotspots (DSHSs, DVHSs, and LHSs) within the structure are identified to promote the enrichment of target contaminants in the optimal hotspot regions. This allows for the detection of micro / nanoplastics smaller than 5 micrometers (down to 10 micrometers) at typical geometric scales. -8 g / L), small molecules (down to 10 g / L)-13 M) and SARS-CoV-2S protein (down to 10 M) and SARS-CoV-2S protein (down to -9 M) is used for high-sensitivity detection.

[0022] The plasmon-enhanced nanocone structure provided by this invention, due to its unique hollow nanocone bimetallic structure, can achieve a maximum strength of 1.1 × 10⁻⁶. 8 Physical enhancement; self-constructed enrichment target stratified analytes targeting size-matched hotspot regions can detect concentrations as low as 10. -8 Micro-nanoplastics at g / L can also simultaneously detect a wide range of contaminants beyond micro-nanoplastics, such as drug molecules, dye molecules, and virus particles.

[0023] The technical solution provided by this invention offers a practical solution for the trace detection of layered micro / nanoplastics and other mixed water pollutants. On the one hand, it can generate high-performance SERS signals; on the other hand, this structure can also effectively modulate the far-field scattering curve, thereby significantly improving the collection efficiency of SERS signals and further increasing the detection limit. This provides a practical approach for the ultrasensitive detection of complex micro / nanoplastics with heterogeneous sizes and / or compositions. Attached Figure Description

[0024] Figure 1 A schematic diagram of BHNC provided by the present invention;

[0025] Figure 2 (ab) is a three-dimensional top view of the structure of the product (i.e., BHNC-Au / Ag-1) obtained in Example 1;

[0026] Figure 2 (cd) is a three-dimensional cross-sectional SEM image of the product (i.e., BHNC-Au / Ag-1) obtained in Example 1;

[0027] Figure 2 (ef) is an EDS element diagram of the structure of the product (i.e., BHNC-Au / Ag-1) obtained in Example 1;

[0028] Figure 3 Far-field radiation maps of the products obtained in Examples 1 and 8-10 were obtained, and all maps were normalized and compared.

[0029] Figure 4 The maximum hot spot intensity of the products obtained in Examples 1 and 8-9 corresponds to the detection of small drug molecules (MNZ drug molecules), SARS-CoV-2S protein and nanoplastics in the samples, respectively;

[0030] Figure 5 Different concentrations of 30, 50, 100, 300, 500, and 1000 nm PS micro / nanoplastics solutions at 1000 cm⁻¹−1 strength. Detailed Implementation

[0031] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0032] Example 1

[0033] Step 1: Select an anodized aluminum template with a V-shaped nanopore structure (referred to as V-shaped AAO template) and perform cleaning and drying pretreatment to remove contaminants from the template surface;

[0034] The macroscopic size of the selected V-shaped AAO template is 2*2 cm; the selected V-shaped AAO template has multiple periodically arranged V-shaped nanopores, the pore diameter (the widest part of the nanopore) of the V-shaped nanopores is 450 nm and the pore depth is 900 nm;

[0035] Step 2: Deposit a gold film on a V-shaped AAO template using electron beam vapor deposition (PVD);

[0036] The specific procedure is as follows: Place a clean and dry V-shaped AAO template and gold target material into the vacuum deposition chamber of the electron beam vapor deposition system, and adjust the gas pressure in the vacuum deposition chamber to 8.0 × 10⁻⁶. -4 Pa, depositing a 250 nm gold film on a V-type AAO template at a rate of 30 nm / min;

[0037] Step 3: The product obtained in Step 2 is etched and demolded using sodium hydroxide solution to obtain the etched cone-shaped gold nanostructure.

[0038] The specific operation is as follows: prepare a sodium hydroxide solution with a concentration of 0.1 mol / L, immerse the V-shaped AAO template obtained in step 2 into the sodium hydroxide solution for etching and demolding; after demolding, use filter paper to remove the etched cone-shaped gold nanostructure from the solution, wash with deionized water to remove sodium hydroxide solution residue, and dry for later use;

[0039] Step 4: Deposit a silver film on the surface of the cone-shaped gold nanostructure using magnetron sputtering technology;

[0040] The specific procedure is as follows: The cleaned and dried cone-shaped gold nanostructure and silver target obtained in step 3 are placed in the vacuum deposition chamber of a magnetron sputtering instrument. Argon gas is introduced, and the pressure in the vacuum deposition chamber is adjusted to 8.0 × 10⁻⁶. -4 A three-dimensional gold-silver hollow conical nanonetwork was obtained by setting the sputtering power to 50 W and the coating time to 10-15 min. The gap size of the three-dimensional gold-silver hollow conical nanonetwork was 20 nm. It was labeled as BHNC-Au / Ag-1.

[0041] Example 2

[0042] The same preparation method as in Example 1 was used, except that the pressure in the vacuum deposition chamber was adjusted to 5.0 × 10⁻⁶ in step 2. -4 Pa was used to deposit a 300 nm gold film at a rate of 40 nm / min. The resulting product was labeled BHNC-Au / Ag-2.

[0043] Example 3

[0044] The same preparation method as in Example 1 was used, except that the pressure in the vacuum deposition chamber was adjusted to 9.0 × 10⁻⁶ in step 2. -4 Pa was used to deposit a 200 nm gold film at a rate of 20 nm / min. The resulting product was labeled BHNC-Au / Ag-3.

[0045] Example 4

[0046] The same preparation method as in Example 1 was used, except that the pressure in the vacuum deposition chamber was adjusted to 5.0 × 10⁻⁶ in step 4. -4 The sputtering power was set to 40 W, the deposition time to 10 min, and the silver film thickness to 20 nm. The resulting product was labeled BHNC-Au / Ag-4.

[0047] Example 5

[0048] The same preparation method as in Example 1 was used, except that the pressure in the vacuum deposition chamber was adjusted to 9.0 × 10⁻⁶ in step 4. -4 The sputtering power was set to 60 W, the deposition time to 30 min, and the silver film thickness to 40 nm. The resulting product was labeled BHNC-Au / Ag-5.

[0049] Example 6

[0050] The same preparation method as in Example 1 was used, except that the gap size of the hollow cone structure was 10 nm. The resulting product was labeled BHNC-Au / Ag-6.

[0051] Example 7

[0052] The same preparation method as in Example 1 was used, except that the gap size of the hollow cone structure was 30 nm. The resulting product was labeled BHNC-Au / Ag-7.

[0053] Example 8

[0054] The same preparation method as in Example 1 was used, except that step 4 was not included. The resulting product was labeled HNC-Au.

[0055] Example 9

[0056] The same preparation method as in Example 1 was used, except that step 4 employed the same process as step 2 to deposit two Au films. The resulting product was labeled HNC-Au-2.

[0057] Example 10

[0058] The same preparation method as in Example 1 was used, except that the template material was a common planar plate-shaped structure material (excluding V-shaped nanoporous structures). The resulting product was labeled P-Au / Ag.

[0059] Example 11

[0060] The same preparation method as in Example 1 was used, except that the template with the V-shaped nanopore structure was selected from a porous silicon template with a V-shaped nanopore structure; the maximum pore diameter of the V-shaped nanopore was 400~500 nm and the pore depth was 800~1000 nm.

[0061] Example 12

[0062] The same preparation method as in Example 1 was used, except that the template with the V-shaped nanopore structure was selected from a titanium dioxide nanotube array template with a V-shaped nanopore structure; the maximum pore diameter of the V-shaped nanopore was 400~500 nm and the pore depth was 800~1000 nm.

[0063] The BHNC-Au / Ag structure provided by this invention enables high-precision SERS detection of micro / nano plastics. The following is in conjunction with... Figures 1-5 This invention describes the structure and mechanism of action of a gold-silver nanoparticle bimetallic hollow nanostructure (BHNC-Au / Ag).

[0064] The following combination Figure 1 The structure and function of the BHNC-Au / Ag structure are explained below:

[0065] Surface-enhanced Raman scattering (SERS) is a highly sensitive spectroscopic detection technique that enables the detection of trace substances, even at the single-molecule level, by significantly enhancing the Raman scattering signal on the surface of metal nanostructures. The enhancement mechanisms for SERS detection mainly include electromagnetic enhancement and chemical enhancement, which rely on the localized surface plasmon resonance effect of the metal surface and the chemical interaction between molecules and the metal surface, respectively. To achieve efficient SERS detection of water-soluble, layered micro / nano-contaminants with poor optical detectability and low concentration, the BHNC-Au / Ag structure provided in this invention improves SERS detection efficiency through three physical enhancement mechanisms.

[0066] (I) Mechanism for enhancing plasmon resonance effect

[0067] The BHNC-Au / Ag structure provided by this invention is designed with a multi-level hierarchical structure on the nanoscale to microscale, which can form a hierarchical high-density local hot spot region. The hot spot region generates a strong local electromagnetic field through the plasmon resonance effect, which can significantly enhance the Raman scattering signal, thereby effectively capturing micro and nano pollutant particles of different sizes and shapes in polluted water samples.

[0068] (ii) Enhancement mechanism of tip effect and interfacial interaction

[0069] Concentration and size-matching optimization of stratified contaminants. The hollow conical design in the BHNC-Au / Ag structure not only possesses a large specific surface area and unique geometric properties, but also effectively concentrates stratified contaminants into a size-matched hotspot region through its tip effect and interfacial forces. At this point, the stratified contaminants are strongly coupled with the electromagnetic field, significantly enhancing the Raman scattering signal intensity of the target molecules. In particular, for complex contaminants such as micro / nanoplastics, the multi-level interactions of their heterogeneous surfaces can further enhance the signal, ensuring both sensitivity and accuracy in detection.

[0070] (III) Enhanced mechanism of directional backscattering over a wide spectral range

[0071] To improve overall detection efficiency, the BHNC-Au / Ag design places particular emphasis on optimizing its optical properties, including the directionality of backscattering and its broadband enhancement performance. The heterogeneous interface of the hollow conical bimetallic structure and its multi-level hotspot distribution not only capture more incident light energy but also effectively guide the scattered light into the detection system. This directional light scattering design maintains strong signal intensity while reducing background noise interference, thereby improving the signal-to-noise ratio and detection reliability.

[0072] Figure 1This is a schematic diagram of the BHNC-Au / Ag structure provided by the present invention. This structure forms a tightly packed network of bimetallic proton nanoparticles (Au and Ag nanoparticles) that self-assemble along the vertical direction. This self-assembly characteristic not only enables the construction of high-density hotspot regions in three-dimensional space but also allows for the distribution of hotspots in different host regions (such as particle interfaces, voids, and tips), thereby significantly enhancing the local electromagnetic field intensity. Due to the three-dimensional distribution characteristics of the hotspots, the BHNC-Au / Ag substrate exhibits excellent efficiency in capturing and enhancing target pollutant signals, particularly for multi-scale detection of stratified pollutants. Secondly, the BHNC-Au / Ag nanoparticles form a highly regular hierarchical V-shaped profile structure through self-assembly. The geometric design of the V-shaped profile effectively guides the direction of light propagation, allowing more scattered light to enter the detection channel, thereby improving the signal-to-noise ratio of the detection system. This geometric structure can also achieve precise control of the hotspot distribution and intensity by adjusting the V-angle, hierarchical spacing, and particle size, further enhancing the enhancement effect. This characteristic makes BHNC-Au / Ag ideal for detecting a wide range of diverse pollutants, especially exhibiting excellent performance over a broad spectral range. In addition to the two key features mentioned above, the BHNC-Au / Ag structure also possesses a unique hierarchical capture mechanism. The multi-level hotspot regions formed by the nanoparticles effectively distinguish pollutants of different sizes and aggregate them into size-matched hotspot regions. For example, particles as small as drug molecules (sub-nanometer scale) or virus particles (tens of nanometer scale), and as large as micro-nanoplastics (size range of 30 nm - 5 μm), can all be concentrated in their respective hotspot regions, thus achieving accurate detection of targets at different scales. This multi-scale hierarchical capture and enhancement characteristic further broadens the applicability of BHNC-Au / Ag in practical applications.

[0073] The following combination Figures 2-5 The test examples illustrate and explain the performance and mechanism of action of the gold-silver nanoparticle bimetallic hollow nanostructure (BHNC-Au / Ag) provided by this invention:

[0074] Test Example 1

[0075] The samples obtained in Example 1 were comprehensively characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), and the results are as follows: Figure 2 As shown in (af). Figure 2 (ab) is a three-dimensional top-view SEM image of the sample structure; Figure 2 (cd) is a three-dimensional cross-sectional SEM image of the sample; Figure 2 (ef) is the EDS elemental map of metallic gold (Au) and silver (Ag) on ​​the sample.

[0076] SEM images (such as) Figure 2As shown in the image (ad), three-dimensional self-assembled bimetallic nanoparticles are tightly packed within a hollow nanocone structure, forming nanoscale gaps. These gaps provide ideal sites for the generation of local hot spots (LHS), and their three-dimensional geometric hierarchical properties further enhance the distribution density of these hot spots. Cross-sectional SEM images reveal the fine structure of the high-density gold nanoparticles (Au-NPs) in BHNC-Au / Ag and the underlying gold film, verifying the mechanical stability and efficient self-assembly of this porous nanocone structure.

[0077] EDS Element Diagram ( Figure 2 (ef) showed the uniform distribution of metallic gold (Au) and silver (Ag) in the nanocone, verifying the compositional uniformity of the structure and the precision of the preparation process.

[0078] In summary Figure 2 The structural characteristics of BHNC-Au / Ag reveal its superior optical properties. The three-dimensional porous nanocones not only effectively enhance the interaction between light and matter but also exhibit excellent performance in adjusting the plasmon working bandwidth and optimizing the backscattering response. This structure allows for precise control of the gap size of the nanocones by adjusting the PVD conditions, providing an efficient physical channel for the enrichment of target molecules. In the experiments shown in this paper, the average gap size of the prepared BHNC-Au / Ag structure was approximately 20 nm. This optimized gap facilitates the capture and enrichment of ultra-low concentration pollutants at target hotspot sites, thereby achieving highly sensitive SERS detection.

[0079] Test Example 2

[0080] The SERS performance of samples prepared in Examples 1 and 8-10 was tested using the three-dimensional finite-difference time-domain (FDTD) method. The far-field direction-dependent backscattering patterns were calculated using FDTD, with a nanoplastic particle placed in the central region of these structures during the calculation. The test results are shown below. Figure 3 As shown.

[0081] like Figure 3 As shown, the Raman scattering angle of the P-Au / Ag structure is within ±82°, which significantly exceeds the collection angle of commonly used Raman instruments. The HNC structure maintains the same collection angle, with the BHNC-Au / Ag structure exhibiting the best performance, possessing a Raman backscattering angle of ±39° and a collection efficiency 1.2 times that of the P-Au / Ag structure. This demonstrates the ability of the BHNC structure to collimate Raman scattered light.

[0082] Meanwhile, finite element method (FEM) calculations also demonstrated the advantages of the BHNC structure in near-field SERS enhancement. Test subjects included small and medium-sized drug molecules (MNZ), SARS-CoV-2 S protein, and nanoplastics; the test results are as follows... Figure 4 As shown.

[0083] Figure 4 The calculated electric field distributions of the samples prepared in Examples 1 and 8-9 under 532 nm excitation are shown. The electric field distribution of BHNC-Au / Ag shows effective optical confinement within the hollow cavity. Maximum local field strength enhancement E max / E0 is 106.3. Notably, we discovered three distinct hotspots: bimetallic hotspot regions (DSHSs) at the top, vertically oriented hotspot regions (DVHSs) within the cavity, and localized hotspot regions (LHSs) on the nanoparticle surface. The generation of DSHSs and DVHSs can be attributed to optical field coupling within the cavity, facilitated by backscattering from the interaction between the connected gold films and gold and silver oxides. Conversely, the LHSs generated by the curved surfaces of the nanoparticles on the inner walls and bottom of the structure primarily originate from near-field coupling between adjacent high-density gold nanoparticles (Au-NPs) and high-density silver nanoparticles (Ag-NPs), as well as the connected gold films. Layered contaminants ranging in size from nanometers to micrometers are deposited on different hotspots, thus enhancing their SERS signals. In contrast, the HNC-Au-2 structure exhibits poor optical confinement. Significant light leakage results in numerous DVHSs regions, which most of the layered plastic particles cannot penetrate. Increasing the gold deposition thickness in the cavity region and on the surface to 250 nm significantly enhances light confinement, but it is still weaker than HNC-Au / Ag.

[0084] Test Example 3

[0085] The performance of the sample structure prepared in Example 1 was systematically characterized using a standard SERS detection procedure. The test objects were 1000 cm⁻¹ PS micro / nanoplastics solutions of different concentrations (30, 50, 100, 300, 500, and 1000 nm). −1 Strength, test results as follows Figure 5 As shown.

[0086] Figure 5 This indicates that hierarchical micro / nanoplastics with a distribution range from 30 nm to 5 μm can be produced even at extremely low concentrations (10⁻⁻⁶). 8Even at concentrations of g / L, clear SERS signals can be generated, fully demonstrating the unique advantages of the BHNC structure in the detection of trace pollutants. Detailed scanning electron microscopy (SEM) analysis further revealed the crucial role of the three-dimensional hotspot regions of the BHNC-Au / Ag structure in capturing hierarchical micro / nanoplastics. The study found that micro / nanoplastics larger than 450 nm are mainly enriched on the surface of the BHNC structure, and their Raman signals are significantly enhanced by the bimetallic hotspot regions (DSHSs) distributed at the top. For plastic particles smaller than 450 nm, due to water pressure, they tend to preferentially concentrate inside the cavity of the BHNC structure. These particles further interact with the high-density nano-gap between bimetallic nanoparticles within the cavity, and their Raman signals are significantly enhanced through vertically oriented hotspot regions (DVHSs) in the cavity and localized hotspot regions (LHSs) on the nanoparticle surface. This hierarchical enrichment and enhancement mechanism not only ensures comprehensive detection of pollutants at different scales but also demonstrates the broad application prospects of the BHNC structure in environmental monitoring.

[0087] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of the present invention, or equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of patent protection of the present invention.

Claims

1. A plasmonic-enhanced nanocone structure, characterized in that: The plasmonic-enhanced nanocone structure is prepared by depositing a gold film on a template with a V-shaped nanopore structure, removing the template by etching to obtain a V-shaped nanocone structure with a gold film deposited, and then depositing a silver film on the V-shaped nanocone structure with a gold film deposited to obtain the plasmonic-enhanced nanocone structure. The pore size of the plasmonic-enhanced nanocone structure is 10~30nm. The maximum pore size of the V-shaped nanopore structure is 400~500nm, and the pore depth is 800~1000nm; The thickness of the gold film in the plasmon-enhanced nanocone structure is 200-300 nm, and the thickness of the silver film is 20-40 nm. The gold film is deposited using electron beam vapor deposition; the silver film is deposited using magnetron sputtering.

2. The plasmon-enhanced nanocone structure according to claim 1, characterized in that: The template is selected from one of the following: anodized aluminum template, porous silicon template, or titanium dioxide nanotube array template.

3. The plasmon-enhanced nanocone structure according to claim 1, characterized in that: The thickness of the gold film in the plasmon-enhanced nanocone structure is 250 nm, and the thickness of the silver film is 30 nm; the pore size of the plasmon-enhanced nanocone structure is 20 nm.

4. A method for preparing a plasmonic-enhanced nanocone structure according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: Step 1: Deposit a gold film on a template with a V-shaped nanopore structure using electron beam vapor deposition; Step 2: Etch and demold the product obtained in Step 1 to obtain a cone-shaped gold nanostructure. Step 3: A plasmonic-enhanced nanocone structure is prepared by depositing a silver film on the cone-shaped gold nanostructure obtained in Step 2 using magnetron sputtering technology.

5. The preparation method according to claim 4, characterized in that: The maximum pore size of the V-shaped nanopore structure described in step 1 is 400~500nm and the pore depth is 800~1000nm; the template is selected from one of the following: anodized aluminum template, porous silicon template or titanium dioxide nanotube array template.

6. The preparation method according to claim 4, characterized in that: In step 1, electron beam vapor deposition involves placing a template with a V-shaped nanopore structure and a gold target in the vacuum deposition chamber of an electron beam vapor deposition apparatus to deposit a gold thin film; the gas pressure in the vacuum deposition chamber is 5 × 10⁻⁶. ‐4 ~9×10 ‐4 Pa, deposition rate is 20~40 nm / min.

7. The preparation method according to claim 4, characterized in that: In step 3, the magnetron sputtering technique involves placing the cone-shaped gold nanostructure and silver target obtained in step 2 into the vacuum deposition chamber of a magnetron sputtering instrument, and introducing an inert gas to deposit a silver thin film; the gas pressure in the vacuum deposition chamber is 5 × 10⁻⁶. ‐4 ~9×10 ‐4 Pa, sputtering power of 40~60W, deposition time of 10~30min.

8. The application of the plasmon-enhanced nanocone structure according to any one of claims 1 to 3 or the plasmon-enhanced nanocone structure obtained by any one of claims 4 to 7 in the SERS detection of layered micro- and nano-scale pollutants.

9. The application of the plasmon-enhanced nanocone structure according to claim 8 in SERS detection of hierarchical micro / nanoscale pollutants, characterized in that, The plasmon-enhanced nanocone structure was used for SERS detection of drug molecules, dye molecules, virus particles, and micro / nanoplastics contaminants.

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