Hollow metal nano array and preparation method and application thereof

Abstract

The invention belongs to the technical field of micro-nano machining, and particularly relates to a hollow metal nano array and a preparation method and application thereof. According to the invention, a regular polymer nano array is prepared based on an ultraviolet light curing nano imprinting technology and a plasma etching technology; then metal evaporation is carried out in combination with an electron beam evaporation dip angle evaporation process, so that the surface of the polymer nano array is partially coated with metal, and a polymer / metal composite nano array with a notch is obtained; and dissolving by using a solvent to remove the water-soluble polymer nano-columns in the polymer / metal nano-array with the notches, so as to prepare the large-area hollow metal nano-array of which the morphology, the size and the period can be flexibly designed. Sulfydryl benzaldehyde molecules are fixed on the surface of the hollow metal nano array to form an SERS (Surface Enhanced Raman Scattering) substrate which is used for detecting hydrazine hydrate. The SERS substrate prepared on the basis of the hollow metal nano array shows high sensitivity, specificity, repeatability and stability.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano fabrication technology, specifically relating to a hollow metal nanoarray, its preparation method, and its application. Background Technology

[0002] Hydrazine hydrate has been clearly defined as a harmful environmental pollutant and a highly toxic substance. Acute exposure can cause immediate poisoning symptoms such as vomiting and dizziness, while long-term exposure may lead to serious consequences such as neurotoxicity, liver and kidney dysfunction, and DNA damage.

[0003] Currently, among the detection technologies for hydrazine hydrate, surface-enhanced Raman scattering (SERS) technology shows great potential in the field of trace substance detection due to its "fingerprint recognition" characteristics, ultra-high detection sensitivity, and non-destructive analysis advantages. SERS enhances the Raman signal of target molecules by several orders of magnitude through the localized surface plasmon resonance effect on the metal substrate surface, enabling structural identification and quantitative analysis of trace molecules.

[0004] Therefore, the realization of SERS performance is highly dependent on the nanostructure of its metallic substrate. Traditionally, noble metal nanomaterials, represented by gold and silver, have been widely used as active substrates for SERS due to their advantages such as localized surface plasmon resonance, ease of synthesis, and good chemical stability. In particular, hollow nanostructures, due to their unique cavity-induced optical resonance enhancement, larger specific surface area, and stronger electromagnetic field localization ability, exhibit superior SERS performance compared to solid structures.

[0005] The preparation of existing hollow nanostructures mostly relies on bottom-up wet chemical synthesis methods. These methods have obvious limitations: it is difficult to achieve precise control over the structural morphology, size and spatial arrangement; at the same time, the preparation process is complex and lengthy, often involving the use of toxic organic solvents or surfactants, which is not environmentally friendly and safe to operate; and the obtained nanoparticles are prone to agglomeration and have poor adhesion to the substrate, resulting in low SERS signal reproducibility, which seriously restricts their practical application.

[0006] In recent years, top-down micro / nano fabrication technologies, such as electron beam lithography, focused ion beam lithography, and laser interference lithography, have been able to achieve high-precision fabrication of nanostructures with narrow gaps, sharp features, and ordered arrangements on designated substrates, enhancing the consistency of SERS signals and avoiding the use of organic solvents and surfactants in wet chemical synthesis methods. However, these methods are expensive, complex, and inefficient, making it difficult to meet the practical application requirements of large-area and low-cost SERS substrates. Furthermore, bottom-up micro / nano fabrication methods, such as those based on porous anodic alumina templates or nanosphere self-assembly, while lower in cost and capable of fabricating certain areas, suffer from significant shortcomings in terms of precise structural controllability, periodic order, and flexibility in fabricating hollow structures, making it difficult to simultaneously ensure the uniformity and designability of SERS substrates. Summary of the Invention

[0007] To address the limitations of existing micro-nano fabrication technologies in achieving both low-cost, large-area production and high-precision controllability, this invention provides a hollow nanoarray, its fabrication method, and its applications.

[0008] This invention utilizes nanoimprinting technology combined with an angled electron beam evaporation process to partially coat the surface of a regular polymer nanoarray with metal, preparing a notched polymer / metal composite nanoarray. Then, the notched polymer / metal composite nanoarray is dissolved in a solvent to obtain a hollow metal nanoarray, thereby achieving effective control over the morphology, size, and periodicity of large-area hollow nanoarrays. The hollow metal nanoarray is then modified with mercaptobenzaldehyde to obtain a high-performance and low-cost SERS substrate.

[0009] The first objective of this invention is to provide a hollow metal nanoarray, comprising the following steps: A water-soluble polymer layer, a silica layer, and a UV-curable imprinting adhesive layer are sequentially prepared on a substrate. The pattern on the template is copied to the imprinting adhesive layer using UV-curable nanoimprinting technology. After etching, an imprinting adhesive nanoarray is obtained. Using the imprinting adhesive nanoarray as a mask, dry etching is performed to transfer the nanopatterns on the imprinting adhesive nanoarray to the water-soluble polymer layer. The imprinting adhesive and silica layer are then removed to obtain a polymer nanoarray. The evaporation angle of the polymer nanoarray is set, and metal evaporation is performed on the polymer nanoarray to coat the surface of the polymer nanoarray and deposit metal into the gaps between the polymer nanoarrays, resulting in a polymer / metal composite nanoarray with notches. The polymer / metal nanoarray with notches is placed in a solvent to dissolve the polymer nanoarray within it, resulting in a hollow metal nanoarray.

[0010] Preferably, the covering angle is 60° to 270°. This invention achieves the desired gap size in the notched polymer / metal nanoarray by adjusting the flipping angle.

[0011] Preferably, the specific method of metal vapor deposition is as follows: The polymer nanoarray is fixed on a substrate at a certain evaporation angle, and a first metal evaporation is performed to coat half of the surface of the polymer nanoarray with metal. Then, metal evaporation is performed by a first flip; then, metal evaporation is performed by a second flip to obtain a polymer / metal nanoarray with notches.

[0012] Preferably, the angle of the first flip is 60° to 90°; the angle of the second flip is 0° to 30°.

[0013] Preferably, the evaporation angle is calculated based on the height, diameter, and period of the polymer nanoarray, and the evaporation angle is the arithmetic mean of θ1 and θ2; where θ1=arctan[H / (PD)]°, θ2=arctan[1.5H / (PD)]°; where H is the height of the polymer nanoarray in nm, D is the diameter of the polymer nanoarray in nm, and P is the period of the polymer nanoarray in nm.

[0014] It should be noted that this invention is based on an angled evaporation process using electron beam evaporation. The minimum evaporation angle θ1 is calculated based on the height, diameter, and period of the polymer nanoarray to ensure subsequent metal coating to the bottom of the polymer nanoarray. The smaller the evaporation angle, the higher the coating height of the polymer nanoarray. Simultaneously, to allow metal to deposit into the gaps between the polymer nanoarrays, the evaporation angle θ2 is calculated using 1.5 times the actual height of the polymer nanoarray as the column height; the arithmetic mean of θ1 and θ2 is used as the actual evaporation angle.

[0015] Preferably, the notched polymer / metal nanoarray is placed in front of the solvent, and the surface of the hollow metal nanoarray is treated with oxygen plasma to enhance wettability, so that aqueous solution molecules or water-soluble Raman molecules in the solvent can better enter the interior of the notched polymer / metal composite nanoarray, thereby improving the solubility of the polymer nanoarray.

[0016] Preferably, the polymer in the water-soluble polymer layer is polyvinyl alcohol or polyvinylpyrrolidone.

[0017] Preferably, the solvent is ethanol or water; when the solvent is ethanol, the dissolution temperature is 35℃~55℃; when the solvent is water, the temperature is 60℃~90℃; and the dissolution time is 48h~60h.

[0018] Preferably, the metal used in the metal vapor deposition is Au or Ag.

[0019] Preferably, the bottom metal thickness of the hollow metal nanoarray is 50nm to 100nm, the top metal thickness is 50nm to 100nm, and the sidewall metal thickness is 25nm to 50nm; the height of the hollow metal nanoarray is 200 to 450nm.

[0020] The second objective of this invention is to provide a hollow metal nanoarray, which is prepared by the above-described method.

[0021] A third objective of this invention is to provide the application of the aforementioned hollow metal nanoarray as a SERS substrate in the detection of hydrazine hydrate.

[0022] The preferred and specific application methods are as follows: Hollow metal nanoarrays were immersed in a mercaptobenzaldehyde solution to react and fix mercaptobenzaldehyde onto the surface of the hollow metal nanoarrays through Au-S bonds, thus obtaining mercaptobenzaldehyde-modified hollow metal nanoarrays as SERS substrates. The SERS substrates were then immersed in a test solution containing hydrazine hydrate to react and detect the signal of hydrazine hydrate.

[0023] Preferably, the concentration of the mercaptobenzaldehyde solution is 10. -4 mol / L~10 -8 mol / L; the solvent for the mercaptobenzaldehyde solution is N,N dimethylformamide.

[0024] Preferably, the hollow metal nanoarray is immersed in a mercaptobenzaldehyde solution at a temperature of 30°C to 50°C for a time of 30 min to 60 min.

[0025] Preferably, the SERS substrate is immersed in the test solution at a temperature of 30℃ to 80℃ for a time of 10 min to 60 min.

[0026] Compared with the prior art, the present invention has the following technical effects: This invention utilizes ultraviolet light curing nanoimprint technology and plasma etching technology to prepare a regular polymer nanoarray. Then, it combines an electron beam evaporation tilting deposition process to perform metal deposition, so that the metal does not completely coat the surface of the polymer nanoarray, thus obtaining a polymer / metal composite nanoarray with gaps. Finally, it uses a solvent to dissolve and remove the water-soluble polymer nanopillars in the polymer / metal nanoarray with gaps, thus preparing a large-area hollow metal nanoarray whose morphology, size and period can be flexibly designed.

[0027] This invention fixes mercaptobenzaldehyde molecules onto the surface of a hollow metal nanoarray as a SERS substrate. Based on the Schiff base reaction, benzaldehyde hydrazone is generated by the reaction of mercaptobenzaldehyde and hydrazine hydrate, thereby achieving the specific recognition and detection of hydrazine hydrate.

[0028] The linear detection range of hydrazine hydrate on the SERS substrate prepared based on hollow metal nanoarrays in this invention is 10. - 4 mol / L~10 -8 mol / L, detection limit is 2.08 × 10⁻⁶ -9 The SERS substrate exhibits high stability and repeatability, with a concentration of mol / L.

[0029] This invention can achieve precise control over the morphology, size, and periodic arrangement of hollow metal nanoarrays while meeting the requirements for low cost and large area fabrication. When applied to the specific identification and detection of hydrazine hydrate, it exhibits high sensitivity, high stability, and high repeatability. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process for preparing a hollow gold nanoarray for use as a SERS substrate for the identification and detection of hydrazine hydrate.

[0031] In the figure, 1-silicon wafer, 2-PVP layer, 3-SiO2 layer, 4-imprint liner layer, 5-imprint liner nanopillar array, 6-PVP nanopillar array, 7-PVP / Au composite nanopillar array with notches, 8-hollow Au nanopillar array, 9-SERS substrate modified with mercaptobenzaldehyde, 10-recognition of hydrazine hydrate based on Schiff base reaction, 11-SERS spectrum.

[0032] Figure 2 Scanning electron microscope (SEM) images of PVP nanopillar arrays, notched PVP / Au composite nanopillar arrays, and hollow Au nanopillar arrays, as well as the ultraviolet (UV) spectrum of the hollow Au nanopillar array, are shown. Specifically, (a) is the SEM image of the PVP nanopillar array; (b) is the SEM image of the notched PVP / Au composite nanopillar array; (c) is the SEM image of the hollow Au nanopillar array; and (d) is the UV spectrum of the hollow Au nanopillar array.

[0033] Figure 3COMSOL models of notched PVA / Au composite nanopillar arrays and hollow Au nanopillar arrays are presented, along with the electric field intensity distributions of notched PVA / Au composite nanopillar arrays and hollow Au nanopillar arrays. Wherein, (a1) is the COMSOL model of the PVA / Au nanopillar array with notches; (a2) is the COMSOL model of the hollow Au nanopillar array; (b1) is the electric field intensity distribution of the PVA / Au composite nanopillar array with notches at a wavelength of 785 nm; (b2) is the electric field intensity distribution of the hollow Au nanopillar array at a wavelength of 785 nm; (c1) is the electric field intensity distribution of the PVA / Au composite nanopillar array with notches at a wavelength of 785 nm; (c2) is the electric field intensity distribution of the hollow Au nanopillar array at a wavelength of 785 nm; (d1) is the electric field intensity distribution of the PVA / Au composite nanopillar array with notches at a wavelength of 785 nm; and (d2) is the electric field intensity distribution of the hollow Au nanopillar array at a wavelength of 785 nm.

[0034] Figure 4 Scanning electron microscope (SEM) images of the PVP nanopillar array prepared in Example 2 and the hollow Au nanopillar arrays prepared in Examples 2 and 3. Specifically, (a) is an SEM image of the PVP nanopillar array prepared in Example 2; (b) is an SEM image of the hollow Au nanopillar array prepared in Example 2; and (c) is an SEM image of the hollow Au nanopillar array prepared in Example 3.

[0035] Figure 5 The images show the SERS spectra and linear relationships of different concentrations of mercaptobenzaldehyde measured in Application Example 2. (a) shows the SERS spectra of different concentrations of mercaptobenzaldehyde measured in Application Example 2; (b) shows the SERS spectra at 1070 cm⁻¹. -1 A linear relationship between the SERS intensity of the mercaptobenzaldehyde peak and the logarithm of the mercaptobenzaldehyde concentration.

[0036] Figure 6 SERS spectra and quantitative analysis diagrams of hydrazine hydrate at different concentrations were determined using a hollow gold nanopillar array modified with mercaptobenzaldehyde. (a) shows the SERS spectra of hydrazine hydrate at different concentrations using the hollow gold nanopillar array modified with mercaptobenzaldehyde; (b) shows the SERS spectra of hydrazine hydrate at 1527 cm⁻¹. -1 The SERS intensity of the hydrazine hydrate peak and the quantitative analysis of hydrazine hydrate concentration are shown in (b); the inset in (b) is at 1527 cm⁻¹. -1 The SERS intensity of the hydrazine hydrate peak and 10 -7 mol / L~10 -8 Linear relationship of hydrazine hydrate concentration in the mol / L range.

[0037] Figure 7Selectivity and ion resistance test patterns of hollow gold nanopillar arrays modified with mercaptobenzaldehyde are shown. (a) is the selectivity test pattern; (b) is the ion resistance test pattern.

[0038] Figure 8 SERS spectra of a hollow gold nanopillar array modified with mercaptobenzaldehyde at 0 days, 1 month, and 6 months, and at 1527 cm⁻¹, were prepared. -1 Reproducibility test results of SERS intensity for hollow gold nanopillar arrays modified with mercaptobenzaldehyde. (a) shows the SERS spectra of the mercaptobenzaldehyde-modified hollow gold nanopillar array at 0 days, 1 month, and 6 months; (b) shows the SERS intensity at 1527 cm⁻¹. -1 Reproducibility test results of SERS intensity for hollow gold nanopillar arrays modified with mercaptobenzaldehyde. Detailed Implementation

[0039] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

[0040] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0041] It should be noted that the English names for aniline, hydroxylamine (HA), L-cysteine ​​(Cys), triethylamine (TEA), dimethylamine (DMA), and methylamine (MA) are all abbreviations for different compounds. The English name for 4-mercaptobenzaldehyde is 4-MBA.

[0042] Example 1 A method for preparing a hollow gold nanoarray includes the following steps: Step 1: Prepare the composite coating: The silicon wafer was ultrasonically cleaned sequentially with acetone and deionized water for 15 minutes, dried with nitrogen, and then placed on a spin coater. A 3 wt% polyvinylpyrrolidone (PVP) aqueous solution was dropped onto the silicon wafer surface and spin-coated at 3000 rpm for 60 seconds to form a uniform PVP layer. Subsequently, a 5 nm thick SiO2 layer was deposited on the PVP layer surface using plasma-enhanced chemical vapor deposition (PECVD). Pentaerythritol acrylate was used as an imprinting adhesive and applied to the SiO2 layer surface. The wafer was left at room temperature for 5 minutes to ensure uniform adhesive coverage, resulting in a composite coating. The average molecular weight of the PVP was 5800.

[0043] Step 2: Preparation of imprinted resist nanopillar array: A PDMS template with a nanopillar pattern of 200 nm in diameter, 300 nm in height and 500 nm in period was brought into close contact with the imprinting adhesive layer in the composite coating and cured under ultraviolet light of 365 nm wavelength and 20 W power for 5 min. After curing, the template was slowly demolded to obtain an imprinting adhesive with a nanopillar pattern.

[0044] Imprinted resist with nanopillar pattern was transferred to a reactive ion etching machine and etched with CHF3 and O2 for 30 s to remove residual imprinted layers, resulting in an imprinted resist nanopillar array.

[0045] Step 3: Fabrication of PVP nanopillar arrays: Using an imprinted nanopillar array as a mask, a mixture of CHF3 and CF4 gas was introduced and etched for 60 seconds to transfer the nanopillar array structure on the imprinted nanopillar array to the SiO2 layer in the composite coating, thus obtaining a SiO2 nanopillar array.

[0046] The etching gas was then switched to O2 at a flow rate of 20 sccm for 90 s to transfer the nanopillar array structure on the SiO2 nanopillar array to the PVP layer in the composite coating. Finally, a mixture of CHF3 and CF4 gas was introduced again for 400 s to remove the SiO2 layer on the PVP layer, resulting in the PVP nanopillar array. The flow rate of CHF3 was 30 sccm and the flow rate of CF4 was 10 sccm.

[0047] Step 4: Prepare a notched PVP / Au composite nanopillar array: Calculate using the following formula: θ1=arctan[H / (PD)]°; θ2=arctan[1.5H / (PD)]°.

[0048] In the formula: H is the height of the PVP nanopillar array, in nm; D is the diameter of the polymer nanopillar array, in nm; P is the period of the polymer nanopillar array, in nm.

[0049] Based on the height, diameter, and period of the PVP nanopillar array, the minimum angle θ1 required to ensure subsequent metal deposition to the bottom of the PVP nanopillar array was calculated to be 56.3°. Simultaneously, to allow metal deposition into the gaps between the PVP nanopillars, the height of the PVP nanopillar array was taken as 1.5 times the actual pillar height H. Substituting this into the formula, the evaporation angle θ2 was calculated to be 45°. The arithmetic mean of θ1 and θ2 was taken as the actual evaporation angle, which is 51°.

[0050] A PVP nanopillar array was fixed on an aluminum stage with a 51° tilt angle and placed in an electron beam evaporation apparatus. Au was used as the evaporation target, and the Au layer deposition rate was controlled at 0.15 nm / s to 0.2 nm / s, with a single deposition thickness of 50 nm. At this point, the Au layer only covered half of the PVP nanopillar array, resulting in a partially coated PVP nanopillar array. Then, using one edge of the partially coated PVP nanopillar array as a reference, it was rotated 90° clockwise and refixed on the stage. Au layer deposition was performed again to form a 270° Au-coated PVP nanopillar array, resulting in a notched PVP / Au composite nanopillar array, which was then treated with oxygen plasma for 30 min.

[0051] Step 5: Fabrication of hollow Au nanopillar arrays: A notched PVP / Au composite nanopillar array was placed in hot water and soaked at 90°C for 50 hours to dissolve the PVP nanopillar array and obtain a hollow Au nanopillar array.

[0052] The surface morphology of the PVP nanopillar array, the notched PVP / Au composite nanopillar array, and the hollow Au nanopillar array in Example 1 were tested, and the results are as follows: Figure 2 As shown.

[0053] like Figure 2 As shown, the PVP nanopillar array has a diameter of 200 nm, a height of 200 nm, and a period of 500 nm; the hollow Au nanopillar array has a gold layer thickness of 100 nm at the top and bottom and a gold layer thickness of 40 nm on the sidewalls.

[0054] Furthermore, the electric field distribution of notched PVP / Au composite nanopillar arrays and hollow Au nanopillar arrays was simulated using COMSOL Multiphysics software, such as... Figure 3 As shown, compared with solid PVA / Au composite nanopillar arrays, hollow gold nanopillar arrays exhibit significant electric field localization at the edges and inside.

[0055] Example 2 A method for preparing a hollow gold nanoarray includes the following steps: Step 1: Prepare the composite coating: The silicon wafer was ultrasonically cleaned sequentially with acetone and deionized water for 15 minutes, dried with nitrogen, and then placed on a spin coater. An 8 wt% polyvinylpyrrolidone aqueous solution was dropped onto the silicon wafer surface and spin-coated at 3000 rpm for 60 seconds to form a uniform PVP layer. Subsequently, a 5 nm thick SiO2 layer was deposited on the PVP layer surface using plasma-enhanced chemical vapor deposition. Pentaerythritol acrylate was used as an imprinting adhesive and applied to the SiO2 layer surface. The wafer was left at room temperature for 5 minutes to ensure uniform coverage of the adhesive layer, resulting in a composite coating.

[0056] Step 2: Preparation of imprinted resist nanopillar array: A PDMS template with a nanopillar pattern of 200 nm in diameter, 450 nm in height and 400 nm in period was brought into close contact with the imprinting adhesive layer in the composite coating and cured under ultraviolet light of 365 nm wavelength and 20 W power for 5 min. After curing, the template was slowly demolded to obtain an imprinting adhesive with a nanopillar pattern.

[0057] Imprinted resist with nanopillar pattern was transferred to a reactive ion etching machine and etched with CHF3 and O2 for 30 s to remove residual imprinted layers, resulting in an imprinted resist nanopillar array.

[0058] Step 3: Fabrication of PVP nanopillar arrays: Using an imprinted nanopillar array as a mask, a mixture of CHF3 and CF4 gas was introduced and etched for 60 seconds to transfer the nanopillar array structure on the imprinted nanopillar array to the SiO2 layer in the composite coating, thus obtaining a SiO2 nanopillar array.

[0059] The etching gas was then switched to O2 at a flow rate of 20 sccm for 180 s to transfer the nanopillar array structure on the SiO2 nanopillar array to the PVP layer in the composite coating. Finally, a mixture of CHF3 and CF4 gas was introduced again for 400 s to remove the SiO2 layer on the PVP layer, resulting in the PVP nanopillar array. The flow rate of CHF3 was 30 sccm and the flow rate of CF4 was 10 sccm.

[0060] Step 4: Prepare a notched PVP / Au composite nanopillar array: Based on the height, diameter, and period of the PVP nanopillar array, the minimum angle θ1 required to ensure subsequent metal deposition to the bottom of the PVP nanopillar array was calculated to be 26.5°. Simultaneously, to allow metal deposition into the gaps between the PVP nanopillars, the height of the PVP nanopillar array was taken as 1.5 times the actual pillar height H. Substituting this into the formula, the evaporation angle θ2 was calculated to be 18.2°. The arithmetic mean of θ1 and θ2 was taken as the actual evaporation angle, which is 22°.

[0061] A PVP nanopillar array was fixed on an aluminum stage at a 22° tilt angle and placed in an electron beam evaporation apparatus. Au was used as the evaporation target, and the deposition rate of the Au layer was controlled at 0.15 nm / s to 0.2 nm / s. The thickness of the Au layer in a single deposition was 50 nm. At this point, the Au layer only covered half of the PVP nanopillar array, resulting in a partially coated PVP nanopillar array. Then, using one edge of the partially coated PVP nanopillar array as a reference, it was rotated 90° clockwise and refixed on the stage. Au layer deposition was performed again to form a 270° Au-coated PVP nanopillar array, resulting in a notched PVP / Au composite nanopillar array. This array was then treated with oxygen plasma for 30 min.

[0062] Step 5: Fabrication of hollow Au nanopillar arrays: A notched PVP / Au composite nanopillar array was placed in hot water and soaked at 90°C for 48 hours to dissolve the PVP nanopillar array and obtain a hollow Au nanopillar array.

[0063] Example 3 A method for preparing a hollow gold nanoarray includes the following steps: The difference from Example 2 is as follows: In step 3, the thickness of the Au layer in a single deposition is 25 nm.

[0064] The surface morphology of the PVP nanopillar array, the hollow Au nanopillar array in Example 2, and the hollow Au nanopillar array prepared in Example 3 were tested, and the results are as follows: Figure 4 As shown.

[0065] like Figure 4 As shown in (a), the PVP nanopillar array has a diameter of 170 nm and a height of 450 nm. Figure 4 As shown in (b), the top gold layer of the hollow Au nanopillar array has a thickness of 100 nm and a diameter of 270 nm, while the sidewall gold layer has a thickness of 50 nm.

[0066] like Figure 4 As shown in (c), the hollow Au nanopillar array prepared in Example 3 has a top gold layer thickness of 50 nm, a diameter of 220 nm, and a sidewall gold layer thickness of 25 nm.

[0067] Application Example 1 A hollow Au nanopillar array modified with mercaptobenzaldehyde was prepared using the hollow Au nanopillar array of Example 1 as a SERS substrate. The specific preparation method is as follows: The hollow Au nanopillar array of Example 1 was immersed in 10 -5The sample was reacted in a mol / L mercaptobenzaldehyde solution with N,N-dimethylformamide as the solvent, at a constant temperature of 30℃ for 30 min. After the reaction was completed, the unbound mercaptobenzaldehyde on the sample surface was washed with N,N-dimethylformamide and irradiated with an infrared lamp until the sample was completely dry, resulting in a mercaptobenzaldehyde-modified hollow Au nanopillar array, which served as the SERS substrate.

[0068] Application Example 2 Following the preparation method of Application Example 1, 10 -4 mol / L, 10 -5 mol / L, 10 -6 mol / L, 10 -7 mol / L and 10 -8 A series of mercaptobenzaldehyde-modified hollow Au nanopillar arrays were prepared by reacting mercaptobenzaldehyde-modified hollow Au nanopillar arrays with mol / L mercaptobenzaldehyde solution. Raman spectroscopy was used for detection, and a standard curve was plotted with peak intensity as the ordinate and the negative logarithm of the mercaptobenzaldehyde concentration as the abscissa. The results are shown below. Figure 5 As shown.

[0069] like Figure 5 As shown in (a), with increasing concentration of mercaptobenzaldehyde, 1070 cm⁻¹ -1 The intensity of the characteristic peaks corresponding to the CS vibration peaks of mercaptobenzaldehyde gradually increases. For example... Figure 5 As shown in (b), the linear equation is y = 480.40x + 4914.98, and the correlation coefficient R0 is... 2 =0.993, indicating that mercaptobenzaldehyde can be stably fixed on the substrate surface, and the signal response has a good linear relationship with concentration.

[0070] Test 1.

[0071] The hollow Au nanopillar array modified with mercaptobenzaldehyde, as described in Application Example 1, was used for the detection of hydrazine hydrate. The specific detection method is as follows: Hollow Au nanopillar arrays modified with mercaptobenzaldehyde were immersed in 10... -4 mol / L, 10 -5 mol / L, 10 - 6 mol / L, 10 -7 mol / L, 10 -8 mol / L and 10 -9 In a hydrazine hydrate solution with a concentration of mol / L, the reaction was carried out at 80℃ for 10 min. After the reaction was complete, the sample was washed with ethanol, dried under infrared light, and then subjected to SERS detection. A quantitative analysis chromatogram was plotted with peak intensity as the ordinate and hydrazine hydrate concentration as the abscissa. The results are shown below. Figure 6 As shown.

[0072] like Figure 6 As shown in (a), as the concentration of hydrazine hydrate decreases, 1527 cm -1 The intensity of the characteristic peak (the C=N vibration peak of benzaldehyde hydrazone) gradually decreases. For example... Figure 6 As shown in (b) of the diagram, in 10 -7 mol / L~10 -8 In the range of mol / L, hydrazine hydrate at 1527 cm⁻¹ -1 The intensity of the characteristic peak at a certain point showed a positive correlation with the concentration of hydrazine hydrate, with the linear equation being y = 3.954 × 10⁻⁶. 9 x+363.5, correlation coefficient R 2 =0.991; the calculated detection limit is 2.08 × 10⁻⁶. -9 mol / L.

[0073] Test 2.

[0074] The selectivity and stability of hydrazine hydrate were tested using a hollow Au nanopillar array modified with mercaptobenzaldehyde as described in Application Example 1. The specific test method is as follows: Hollow Au nanopillar arrays modified with mercaptobenzaldehyde were immersed in 10... -5 mol / L ammonia water, 10 -5 mol / L aniline, 10 -5 mol / L hydroxylamine, 10 -5 L-cysteine ​​at mol / L, 10 -5 mol / L triethylamine, 10 -5 mol / L dimethylamine and 10 -5 mol / L methylamine, reacted at 80℃ for 10 min; a hollow Au nanopillar array modified with mercaptobenzaldehyde was immersed in a solution containing Ba 2+ Ca 2+ Mg 2+ Zn 2+ Fe 2+ Fe 3+ Na + K + Cl - and SO4 2- Concentration of 10 -5 The reaction was carried out with a mol / L ionic solution at a constant temperature of 80℃ for 10 min. After the reaction was completed, the solution was rinsed with deionized water, dried under infrared lamp, and then subjected to SERS detection. The results are as follows: Figure 7 As shown.

[0075] like Figure 7 As shown in (a), only the hydrazine hydrate sample was at 1527 cm⁻¹. -1The presence of a distinct characteristic peak indicates that the reaction between mercaptobenzaldehyde and hydrazine hydrate produces benzaldehyde hydrazone. This demonstrates that the hollow Au nanopillar array modified with mercaptobenzaldehyde exhibits high specificity for hydrazine hydrate and can be used to selectively distinguish N2H4 in complex real-world samples.

[0076] like Figure 7 As shown in (b), even in the presence of high concentrations of ions, the characteristic peak intensity of hydrazine hydrate did not change significantly, indicating that the hollow Au nanopillar array modified with mercaptobenzaldehyde has excellent selectivity and anti-interference ability for hydrazine hydrate.

[0077] Test 3.

[0078] like Figure 8 As shown in (a), after the hollow Au nanopillar array modified with mercaptobenzaldehyde was placed for 1 month and 6 months, the signal intensity of hydrazine hydrate was tested and the change was very small; this shows that the hollow Au nanopillar array modified with mercaptobenzaldehyde prepared in the embodiments of the present invention has good stability.

[0079] Ten sites were randomly selected on a hollow Au nanopillar array modified with mercaptobenzaldehyde to detect hydrazine hydrate signals. The relative standard deviation of the SERS characteristic peak intensities of the 10 parallel samples was calculated to be around 1527 cm⁻¹. -1 The value was 2.4%; this indicates that the hollow Au nanopillar array modified with mercaptobenzaldehyde prepared in the embodiments of the present invention has good repeatability and can be applied to the quantitative analysis of surface-enhanced Raman spectroscopy of hydrazine hydrate.

[0080] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0081] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If these modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a hollow metal nanoarray, characterized in that, Includes the following steps: A water-soluble polymer layer, a silica layer, and a UV-curable imprinting adhesive layer are sequentially prepared on a substrate. By using ultraviolet light curing nanoimprint technology, the pattern on the template is copied to the imprinting adhesive layer, and after etching, an imprinting adhesive nanoarray is obtained. Using an imprinted resist nanoarray as a mask, dry etching is performed to transfer the nanopatterns on the imprinted resist nanoarray to a water-soluble polymer layer. The imprinted resist and silica layer are then removed to obtain a polymer nanoarray. By setting the evaporation angle of the polymer nanoarray, metal evaporation is performed on the polymer nanoarray, so that the metal part is coated on the surface of the polymer nanoarray and the metal is deposited into the gaps between the polymer nanoarrays, resulting in a polymer / metal composite nanoarray with gaps. A notched polymer / metal nanoarray is placed in a solvent to dissolve the polymer nanoarray, thus obtaining a hollow metal nanoarray.

2. The method for preparing hollow metal nanoarrays according to claim 1, characterized in that, The arithmetic mean of the evaporation angles θ1 and θ2: θ1=arctan[H / (PD)]°, θ2=arctan[1.5H / (PD)]°; Where H is the height of the polymer nanoarray in nm, D is the diameter of the polymer nanoarray in nm, and P is the period of the polymer nanoarray in nm.

3. The method for preparing a hollow metal nanoarray according to claim 1, characterized in that, The covering angle is 60° to 270°.

4. The method for preparing a hollow metal nanoarray according to claim 1, characterized in that, The polymer in the water-soluble polymer layer is polyvinyl alcohol or polyvinylpyrrolidone.

5. The method for preparing a hollow metal nanoarray according to claim 1, characterized in that, The solvent is ethanol or water; when the solvent is ethanol, the dissolution temperature is 35℃~55℃; when the solvent is water, the dissolution temperature is 60℃~90℃. The dissolution time was 48h to 60h.

6. The method for preparing a hollow metal nanoarray according to claim 1, characterized in that, The metal used in metal vapor deposition is Au or Ag.

7. A hollow metal nanoarray, characterized in that, The hollow metal nanoarray is prepared by the method described in any one of claims 1 to 6.

8. The application of a hollow metal nanoarray as a SERS substrate in the detection of hydrazine hydrate, characterized in that, The hollow metal nanoarray is the hollow metal nanoarray described in claim 7.

9. The application of the hollow metal nanoarray according to claim 8 as a SERS substrate in the detection of hydrazine hydrate, characterized in that, The specific application methods are as follows: Hollow metal nanoarrays were immersed in a mercaptobenzaldehyde solution to react, so that mercaptobenzaldehyde was fixed on the surface of the hollow metal nanoarrays through Au-S bonds, thus obtaining mercaptobenzaldehyde-modified hollow metal nanoarrays as SERS substrates. The SERS substrate was immersed in a test solution containing hydrazine hydrate for reaction, and the signal of hydrazine hydrate was detected.

10. The application of the hollow metal nanoarray according to claim 9 as a SERS substrate in the detection of hydrazine hydrate, characterized in that, The concentration of the mercaptobenzaldehyde solution is 10. -4 mol / L~10 -8 mol / L; the solvent for the mercaptobenzaldehyde solution is N,N dimethylformamide.

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