阅读说明：本技术 银纳米颗粒组装的空腔结构阵列及其制备方法和用途 (Cavity structure array assembled by silver nanoparticles and preparation method and application thereof ) 是由 朱储红 赵强生 袁玉鹏 杜海威 于 2020-07-08 设计创作，主要内容包括：本发明公开了一种银纳米颗粒组装的空腔结构阵列及其制备方法和用途。结构由导电衬底和其上的银纳米结构组成,其中,银纳米结构为银纳米颗粒堆积的多孔薄膜、且孔洞为有序排列的球形空腔结构；制备方法为先将硝酸银粉末、柠檬酸粉末、乙二胺四乙酸粉末、亚硫酸钠粉末和磷酸氢二钾粉末溶解于水中,得到电解液；再将依次溅射有15-30nm厚金膜和覆盖一层及以上聚苯乙烯微球晶体模板的导电衬底作为阴极、石墨片作为阳极置于电解液中电沉积,在导电衬底上制得目的产物。制备的银纳米颗粒组装的空腔结构阵列具有三维分布的SERS热点,SERS灵敏度高,能够检测浓度低至1fmol/L的罗丹明6G,极易于广泛地商业化作为表面增强拉曼散射的活性基底。(The invention discloses a cavity structure array assembled by silver nanoparticles and a preparation method and application thereof. The structure consists of a conductive substrate and a silver nano structure on the conductive substrate, wherein the silver nano structure is a porous film stacked by silver nano particles, and holes are spherical cavity structures arranged in order; the preparation method comprises the steps of dissolving silver nitrate powder, citric acid powder, ethylene diamine tetraacetic acid powder, sodium sulfite powder and dipotassium hydrogen phosphate powder in water to obtain electrolyte; then taking the conductive substrate which is sputtered with a gold film with the thickness of 15-30nm and covered with one or more layers of polystyrene microsphere crystal templates as a cathode and a graphite sheet as an anode, placing the conductive substrate and the graphite sheet in electrolyte for electrodeposition, and preparing a target product on the conductive substrate. The prepared cavity structure array assembled by the silver nanoparticles has SERS hot spots distributed in three dimensions, is high in SERS sensitivity, can detect rhodamine 6G with the concentration as low as 1fmol/L, and is extremely easy to be widely commercialized as an active substrate for surface-enhanced Raman scattering.)

1. A cavity structure array assembled by silver nanoparticles is characterized in that the cavity structure array is a layer of porous film (1) or a superposition of two or more layers of porous films (1), the porous films (1) are attached to the surface of a gold film (2), the gold film (2) is laid on the surface of a conductive substrate (3), the porous films (1) are obtained by closely arranging cavity structure units, the cavity structure units are round shells with cavities (4) and with the inner diameters of 500-5000nm and the standard deviation of the inner diameters of less than 5%, the shells of the adjacent cavity structure units are mutually abutted, round holes (6) with the diameters of 50-1000nm are arranged at the abutted positions so that the adjacent cavity structure units are communicated with each other, and round holes (5) which are approximately round and penetrate through the shells are uniformly distributed on one side of the cavity structure unit of the outermost layer of the porous film (1) far away from the gold film (2), the diameter of the round hole (5) is 200-4000nm and smaller than the inner diameter of the cavity structure unit, the cavity structure unit is formed by piling and assembling silver nanoparticles, and the silver nanoparticles are approximately spherical particles with the diameter of 10-200 nm.

2. The silver nanoparticle-assembled cavity structure array according to claim 1, wherein the roughness of the inner wall of the cavity structure unit is 20-40 nm.

3. A method for preparing a cavity structure array assembled by silver nano-particles according to any one of claims 1 to 2, which comprises the following steps:

s1, weighing the components according to the weight ratio of (0.05-0.15) to (0.5-1.5) to (0.03-0.11) to (0.25-0.75) to (0.1-0.3) to (45-55) of silver nitrate powder, citric acid powder, ethylene diamine tetraacetic acid powder, sodium sulfite powder, dipotassium hydrogen phosphate powder and water, sequentially dissolving the silver nitrate powder, the citric acid powder, the ethylene diamine tetraacetic acid powder, the sodium sulfite powder and the dipotassium hydrogen phosphate powder in water to obtain a mixed solution, and fully stirring the mixed solution to obtain an electrolyte;

s2, sputtering a gold film (2) with the thickness of 15-30nm on a conductive substrate (3) by using an ion sputtering instrument to obtain the conductive substrate (3) coated with the gold film (2), preparing a single-layer polystyrene microsphere crystal template with the diameter of 500-;

or repeating the step of preparing the polystyrene microsphere crystal template by the liquid level self-assembly method and drying in an oven for more than 1 time to prepare the conductive substrate (3) sequentially coated with the gold film (2) and two or more layers of polystyrene microsphere crystal templates;

s3, placing the conductive substrate (3) covered with the gold film (2) and the polystyrene microsphere crystal template prepared in the step S2 as a cathode and a graphite sheet as an anode in electrolyte at room temperature, wherein the current density is 50-120 mu A/cm²Is electrodeposited at constant current of 5-50min, electrodepositing silver nanoparticles in gaps of the polystyrene microsphere crystal template array, removing the polystyrene microsphere crystal template by using a chemical corrosion method, and cleaning the cavity structure array from which the polystyrene microsphere crystal template is removed to obtain a cavity structure array assembled by the silver nanoparticles;

wherein, the steps S1 and S2 are not in sequence.

4. The method for preparing a cavity structure array assembled by silver nanoparticles as claimed in claim 3, wherein the conductive substrate (3) in step S2 is indium tin oxide glass, silicon wafer, fluorine-doped SnO₂Any one of conductive glasses.

5. The method for preparing a cavity structure array assembled by silver nanoparticles as claimed in claim 3, wherein the conductive substrate (3) is sequentially cleaned by acetone, ethanol and deionized water before the gold film (2) is sputtered on the conductive substrate (3) in step S2.

6. The method for preparing a silver nanoparticle-assembled cavity structure array according to claim 3, wherein the chemical etching method in step S3 is specifically performed by immersing the conductive substrate (3) on which the silver nanoparticles are deposited in a tetrachloromethane or dichloromethane or trichloromethane solution until the polystyrene microsphere crystals are completely dissolved.

7. The method for preparing a cavity structure array assembled by silver nanoparticles according to claim 3, wherein the cavity structure array after the polystyrene microsphere crystal template is removed is cleaned in a manner of cleaning with deionized water for 1-3 times, then blow-drying with nitrogen, and then cleaning with plasma in step S3.

8. Use of an array of cavity structures assembled by silver nanoparticles according to claim 1 or 2 as an active substrate for surface enhanced raman scattering.

9. The use of the silver nanoparticle-assembled cavity structure array according to claim 8, wherein the silver nanoparticle-assembled cavity structure array is used as an active substrate for surface enhanced Raman scattering, a laser Raman spectrometer is used for measuring the content of dye molecule rhodamine 6G attached to the cavity structure array, and the lower detection limit is 0.1 fmol/L.

10. Use of an array of silver nanoparticle assembled cavity structures according to claim 9, wherein the laser raman spectrometer has excitation light with a wavelength of 532nm, an output power of 0.05-1mW, an integration time of 5-60s at the time of measurement, and an integration number of 1-5.

Technical Field

The invention relates to the technical field of nano materials, in particular to a silver nanoparticle assembled cavity structure array and a preparation method and application thereof.

Background

Surface Enhanced Raman Scattering (SERS) technology, which can provide spectra with fingerprint information, is one of the most sensitive analytical detection techniques. SERS spectra have wide application in the fields of chemistry, biology, medicine, environmental detection and the like. At present, for the wide application of the SERS detection technology, one of the key problems to be solved is to develop a substrate with high SERS activity and good signal repeatability. For this reason, there have been continuous efforts, for example, an article entitled "Green Synthesis of Large-Scale high Ordered Core @ Shell Nanoporus Au @ Ag NanoprodArrays as Sensitive and reproducible3D SERS Substrates", ACS Appl. Mater. interfaces 2014,6,15667-15675 ("Green Synthesis of Large area highly Ordered arrays of gold Core/silver Shell Nanoporous structures useful as Sensitive and reproducible three-dimensional SWERS Substrates", volume 6,15667-15675 of the American society for chemical applications materials interface 2014). In the article, gold-silver alloy nanorods are grown in pores of a porous anodic alumina template by an electrodeposition method. The alloy nanorod has a smooth surface, and is not beneficial to obtaining high SERS activity. Therefore, the alloy nano-rods are dealloyed, so that a large number of nano-holes are manufactured, and the roughness of the nano-rods is improved. In order to further improve the SERS activity, a layer of thin silver is deposited on the surface of the porous gold nanorod. Although the product has high SERS activity, the uniformity and repeatability of SERS signals of different batches of samples are easily influenced due to complex preparation steps.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a cavity structure array assembled by silver nanoparticles;

in order to overcome the defects in the prior art, the invention provides a simple preparation method of a cavity structure array assembled by silver nanoparticles;

in order to overcome the defects in the prior art, the invention provides the application of the silver nanoparticle assembled cavity structure array;

in order to solve the technical problem of the invention, the adopted technical scheme is a cavity structure array assembled by silver nanoparticles, the cavity structure array is a layer of porous film or a superposition of two or more layers of porous films, the porous films are attached to the surface of a gold film, the gold film is laid on the surface of a conductive substrate, the porous films are obtained by closely arranging cavity structure units, the cavity structure units are circular shells with cavities, the inner diameter of the cavity structure units is 500 plus 5000nm, and the standard deviation of the inner diameter is less than 5%, the shells of the adjacent cavity structure units are mutually abutted, circular holes with the diameter of 50-1000nm are arranged at the abutted positions so that the adjacent cavity structure units are communicated with each other, a circular hole penetrating through the shells and close to a circular shape is uniformly distributed on one side of the cavity structure unit of the outermost layer of the porous film far away from the gold film, and the diameter of the circular hole is 200 plus 4000nm and is smaller than the inner diameter of the cavity structure units, the cavity structural unit is formed by piling and assembling silver nanoparticles, and the silver nanoparticles are approximately spherical particles with the diameter of 10-200 nm.

As a further improvement of the cavity structure array assembled by the silver nanoparticles:

preferably, the roughness of the inner wall of the cavity structural unit is 20-40 nm.

In order to solve another technical problem of the present invention, the technical scheme adopted is a preparation method of a silver nanoparticle assembled cavity structure array, comprising the following steps:

s1, weighing the components according to the weight ratio of (0.05-0.15) to (0.5-1.5) to (0.03-0.11) to (0.25-0.75) to (0.1-0.3) to (45-55) of silver nitrate powder, citric acid powder, ethylene diamine tetraacetic acid powder, sodium sulfite powder, dipotassium hydrogen phosphate powder and water, sequentially dissolving the silver nitrate powder, the citric acid powder, the ethylene diamine tetraacetic acid powder, the sodium sulfite powder and the dipotassium hydrogen phosphate powder in water to obtain a mixed solution, and fully stirring the mixed solution to obtain an electrolyte;

s2, sputtering a gold film with the thickness of 15-30nm on a conductive substrate by using an ion sputtering instrument to prepare the conductive substrate coated with the gold film, preparing a single-layer polystyrene microsphere crystal template with the diameter of 500 plus 5000nm by using a liquid level self-assembly method, transferring the polystyrene microsphere crystal template to the gold film of the conductive substrate by using a liquid level transfer method, then placing the conductive substrate coated with the gold film and the polystyrene microsphere crystal template into a drying oven with the temperature of 105 plus 115 ℃, taking out after 15min, and preparing the conductive substrate sequentially coated with the gold film and the single-layer polystyrene microsphere crystal template;

or repeating the step of preparing the polystyrene microsphere crystal template by the liquid level self-assembly method and drying in an oven for more than 1 time to prepare the conductive substrate sequentially coated with the gold film and two or more layers of polystyrene microsphere crystal templates;

s3, placing the conductive substrate covered with the gold film and the polystyrene microsphere crystal template prepared in the step S2 as a cathode and a graphite sheet as an anode in electrolyte at room temperature, wherein the current density is 50-120 muA/cm²Carrying out electrodeposition for 5-50min under constant current, electrodepositing silver nanoparticles in gaps of the polystyrene microsphere crystal template array, removing the polystyrene microsphere crystal template by using a chemical corrosion method, and cleaning the cavity structure array from which the polystyrene microsphere crystal template is removed to obtain a cavity structure array assembled by the silver nanoparticles;

wherein, the steps S1 and S2 are not in sequence.

The preparation method of the cavity structure array assembled by the silver nano-particles is further improved as follows:

preferably, in step S2, the conductive substrate is any one of indium tin oxide glass, silicon wafer, and fluorine-doped SnO2 conductive glass.

Preferably, before the gold film is sputtered on the conductive substrate in step S2, the conductive substrate is sequentially cleaned by using acetone, ethanol and deionized water.

Preferably, the chemical etching method in step S3 is specifically performed by immersing the conductive substrate deposited with silver nanoparticles in a solution of tetrachloromethane or dichloromethane or trichloromethane until the polystyrene microsphere crystals are completely dissolved.

Preferably, the step S3 of cleaning the cavity structure array after removing the polystyrene microsphere crystal template includes cleaning with deionized water for 1-3 times, blow-drying with nitrogen, and cleaning with plasma.

In order to solve another technical problem of the invention, the technical scheme is the application of a cavity structure array assembled by silver nanoparticles as an active substrate for surface-enhanced Raman scattering.

The application of the cavity structure array assembled by the silver nanoparticles as an active substrate for surface-enhanced Raman scattering is further improved:

preferably, the cavity structure array assembled by the silver nanoparticles is used as an active substrate for surface enhanced Raman scattering, a laser Raman spectrometer is used for measuring the content of dye molecule rhodamine 6G attached to the cavity structure array, and the lower detection limit reaches 0.1 fmol/L.

Preferably, the wavelength of the exciting light of the laser Raman spectrometer is 532nm, the output power is 0.05-1mW, the integration time in measurement is 5-60s, and the integration frequency is 1-5 times.

Compared with the prior art, the invention has the beneficial effects that:

(1) the cavity structure array assembled by silver nanoparticles is formed by piling a large number of silver nanoparticles with the diameters within the range of 20-200nm, and a large number of SERS hot points can be provided at the gaps of the silver nanoparticles, so that the cavity structure array structure has high SERS sensitivity.

(2) The invention discloses a method for preparing a cavity structure array assembled by silver nanoparticles by one step by using a template method, which is simple, convenient and feasible to operate, so that the uniformity and batch repeatability of SERS substrate signals in different batches can be easily ensured in the preparation process. The electrolyte formula used has characteristics and advantages, the conductive substrate is a semi-conductive or fully-conductive substrate, which can ensure that silver nanoparticles are uniformly filled in gaps of the polystyrene sphere template in a large area and can ensure that silver materials are piled up in a nanoparticle form instead of forming a structure which is densely piled up, has no gap on the inner wall of a spherical cavity and has low roughness (less than 5 nm).

(3) The cavity array structure assembled by the silver nanoparticles prepared by the invention can be used as an active substrate for surface enhanced Raman scattering, has three-dimensionally distributed SERS hot spots, is high in SERS sensitivity, and can detect rhodamine 6G with the concentration as low as 1 fmol/L.

Drawings

FIG. 1 is a cross-sectional structure diagram of a cavity structure array assembled by a conductive substrate, a gold film and silver nanoparticles;

fig. 2 is an electron microscope scanning image of a cavity structure array sample 1 assembled by silver nanoparticles, wherein (a) is a front scanning image, (b) is a cross-sectional scanning image, and (c) is a scanning image of the inner wall of a cavity structure unit;

FIG. 3 shows the results of characterization of a cavity structure array sample 2 assembled by silver nanoparticles containing 1fmol/L rhodamine 6G using a confocal laser Raman spectrometer.

The designations in the drawings have the following meanings:

1. a porous film; 2. gold film; 3. a conductive substrate; 4. a cavity; 5. a circular hole; 6. and (4) holes.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

First commercially available or prepared by conventional methods: silver nitrate powder, citric acid powder, ethylene diamine tetraacetic acid powder, sodium sulfite powder, dipotassium hydrogen phosphate powder, deionized water or distilled water as water, and graphite flake.