阅读说明：本技术 基于v型腔阵列表面的可控电镀法在制备高灵敏sers基底中的应用 (Application of controllable electroplating method based on V-shaped cavity array surface in preparation of high-sensitivity SERS substrate ) 是由 方靖淮 刘闯 王素 吴静 于 2021-08-30 设计创作，主要内容包括：本发明提供了一种基于V型腔阵列表面的可控电镀法在制备高灵敏SERS基底中的应用,包括：1)制备电镀模板,采用V型腔体结构的AAO模板,以固定角度及恒定速率蒸镀10nm铬和120nm银,形成一层紧密结合的AAO银膜电镀层；2)制备电镀液,配制3.3mM氯金酸和0.1M氢氟酸的混合液；3)电化学可控组装,采用三电极的电化学工作站,电镀模板作为工作电极,铂片电极作为对电极,Ag/AgCl-(2)作为参比电极,在0.1mA/cm～(2)的恒电流密度下进行沉积生长并记录。本发明中的金纳米粒子在V型腔阵列表面可实现定向可控沉积,且获得的高灵敏SERS基底可达到单分子检测水平,对R6G的检测限可低至10～(-18)M。(The invention provides an application of a controllable electroplating method based on a V-shaped cavity array surface in preparation of a high-sensitivity SERS substrate, which comprises the following steps: 1) preparing electroplating template by adopting an AAO template with a V-shaped cavity structure at a fixed angle and constant speedEvaporating 10nm chromium and 120nm silver to form a layer of tightly combined AAO silver film electroplated layer; 2) preparing electroplating solution, namely preparing a mixed solution of 3.3mM chloroauric acid and 0.1M hydrofluoric acid; 3) electrochemical controllable assembly, adopting three-electrode electrochemical workstation, electroplating template as working electrode, platinum sheet electrode as counter electrode, Ag/AgCl 2 As a reference electrode, at 0.1mA/cm 2 The deposition growth was carried out at constant current density and recorded. The gold nanoparticles can realize directional controllable deposition on the surface of a V-shaped cavity array, the obtained high-sensitivity SERS substrate can reach the single-molecule detection level, and the detection limit of R6G can be as low as 10 ‑18 M。)

1. The application of a controllable electroplating method based on a V-shaped cavity array surface in preparation of a high-sensitivity SERS substrate is characterized in that: the method comprises the following steps:

step (1) preparing an electroplating template: selecting a cleaned AAO template with a V-shaped aperture, wherein the model parameters are as follows: the top is a hexagonal hole with the aperture of 450nm, the bottom is a circular pocket bottom with the aperture of 100nm, and the hole depth is 400 nm; firstly, evaporating a layer of metal chromium with the thickness of 10nm on the surface of AAO by using a vacuum film plating machine, wherein the constant evaporation rate is 0.2 angstrom/second; then, continuously evaporating a layer of 120nm silver film at the same evaporation rate to form a layer of thin electro-silver film, and covering the inner wall and the surface of the V-shaped cavity of the whole AAO to obtain the electroplating template with the V-shaped cavity body structure;

preparing electroplating solution in step (2): preparing a mixed solution of 3.3mM chloroauric acid and 0.1M hydrofluoric acid, wherein the used water is deionized water with EW-I standard;

and (3) electrochemical controllable assembly: adopting a three-electrode electrochemical workstation, taking the electroplating template obtained in the step (1) as a working electrode, taking a platinum sheet electrode as a counter electrode, and taking Ag/AgCl₂As a reference electrode, at 0.1mA/cm²The current density is deposited for different time to obtain the high-sensitivity SERS substrate with uniform appearance.

2. The method for controllably assembling the high-performance uniform SERS substrate of the electrodeposited gold nanoparticles of the V-shaped thin electrodeposited silver film according to claim 1, which is characterized in that: in the step (3), the electrochemical deposition method is a chronopotentiometry method, and the constant rate is 0.1mA/cm²The current density of (a) is deposited.

3. The application of the controllable electroplating method based on the V-shaped cavity array surface in the preparation of the high-sensitivity SERS substrate according to claim 1 is characterized in that: in the step (3), the electrochemical deposition is optimal for 400s, the SERS signal is strongest at the time, and the detection limit for R6G can be as low as 10^-18M。

Technical Field

The invention relates to the technical field of electrochemical directional controllable deposition, and Au is utilized⁺The nano-gold multilevel aggregate with the high chemical stability structure and the gap below 10 nanometers greatly enhances the Raman signal of probe molecules, and particularly relates to a structural design, a preparation method and application of nano-gold attached to the surface of a V-shaped cavity array.

Background

Surface Enhanced Raman Scattering (SERS) is an extremely sensitive molecular fingerprint technique, is widely used for trace monitoring of various molecules, can detect chemical substances down to a single-molecule level, and has important applications in the fields of biology, medicine, virus detection, and the like. High performance SERS substrates depend on the intensity and size of the "hot spot" in the substrate, which is mainly generated at the tip and small gap (< 10nm) of the metal nanostructure. The SERS substrate generally adopts nano gold and nano silver as a nano structure of the substrate, and has good biocompatibility. Based on the remarkable advantages, the kit has good prospect in the aspect of specifically detecting various molecules.

However, the cost of the current high-performance SERS enhancing substrate is high, and a regular periodic array in morphology is generally required to be prepared by a fine micro-nano processing means to ensure the uniformity and reproducibility of the substrate, but the fine nano processing apparatus is very expensive and has poor cost benefit. Therefore, developing a cost-effective method to fabricate large-area, topographically uniform nanostructured surfaces is the ultimate goal pursued by SERS.

The electrodeposition technology is widely applied to the growth of metal such as a nano column and a nano ring, and the nano-scale growth of the metal can be realized by controlling the deposition potential and the charge density, however, most of the work is electrodeposition and limited deposition of metal nanoparticles, most of the deposited morphology is accumulation of metal particles, and the arrangement of the metal particles with nano gaps is difficult to realize. Therefore, the development of an assembly of directionally controllable gold nanoparticles is also the final goal pursued by electroplating.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problems, the gold nanoparticles are assembled by controlling the charge density through an electroplating method in electrochemistry, a silver film with a hierarchical structure in a V-shaped cavity body is obtained by carrying out vacuum evaporation on a V-shaped AAO template, and the charge density in the electroplating process is further controlled. The controllable deposition of gold nanoparticles is realized by utilizing the difference of charge densities of different sites on the surface of the cavity array, and a plasmon V-shaped cavity body membrane with a gap smaller than 10 nanometers is formed. The Ag and Au composite nano structure is utilized to generate huge electromagnetic enhancement, and Au particles in the shape of a 'hierarchical ring' with nano gaps form multiple 'hot spots', so that the adsorption capacity of the SERS substrate is greatly improved, and the high-sensitivity detection of the substrate is realized.

The technical scheme is as follows: in order to achieve the purpose, the invention provides the following scheme:

1. an application of a controllable electroplating method based on a V-shaped cavity array surface in preparation of a high-sensitivity SERS substrate comprises the following steps:

step (1) preparing an electroplating template: selecting a cleaned AAO template with a V-shaped aperture, wherein the model parameters are as follows: the top is a hexagonal hole with the aperture of 450nm, the bottom is a circular pocket bottom with the aperture of 100nm, and the hole depth is 400 nm; firstly, evaporating a layer of metal chromium with the thickness of 10nm on the surface of AAO by using a vacuum film plating machine, wherein the constant evaporation rate is 0.2 angstrom/second; then, continuously evaporating a layer of 120nm silver film at the same evaporation rate to form a layer of thin electro-silver film, and covering the inner wall and the surface of the V-shaped cavity of the whole AAO to obtain the electroplating template with the V-shaped cavity body structure;

preparing electroplating solution in step (2): preparing a mixed solution of 3.3mM chloroauric acid and 0.1M hydrofluoric acid, wherein the used water is deionized water with EW-I standard;

and (3) electrochemical controllable assembly: adopting a three-electrode electrochemical workstation, taking the electroplating template obtained in the step (1) as a working electrode, taking a platinum sheet electrode as a counter electrode, and taking Ag/AgCl₂As a reference electrode, at 0.1mA/cm²The current density is deposited for different time to obtain the high-sensitivity SERS substrate with uniform appearance.

Further, in the step (3), the electrochemical deposition method is chronopotentiometry and is constant at 0.1mA/cm²The current density of (a) is deposited.

Further, in step (3), the electrochemical deposition is optimal for 400s, the SERS signal is strongest and the detection limit for R6G can be as low as 10^-18M。

Has the advantages that: compared with the prior art, the invention has the following specific advantages:

1. the preparation method can rapidly prepare a large amount of high-performance SERS substrates, and can reach the level of single molecule detection;

2. the preparation method is electroplating assembly of directionally controllable nano gold particles, and has high social market value and application prospect;

3. the preparation method provided by the invention considers cost benefits, integrates low cost, high performance, high sensitivity and the like, is a final target pursued by the SERS substrate, and has important significance in the aspect of low-concentration trace detection.

Drawings

Fig. 1 is a flow chart of an application of the controllable electroplating method based on the V-cavity array surface in the preparation of a high-sensitivity SERS substrate according to the present invention.

Fig. 2 is a high resolution image of a plating stencil of the present invention.

FIG. 3 shows the plating solution of the present invention at 0.1mA/cm²A planar high resolution image of 400s was deposited at a current density of (1).

FIG. 4 shows the plating solution of the present invention at a rate of 0.1mA/cm²A lateral high resolution image of 400s was deposited at a current density of (a).

FIG. 5 shows the plating solution of the present invention at a rate of 0.1mA/cm²A planar high resolution image of 100s was deposited at a current density of (a).

FIG. 6 shows the plating solution of the present invention at a rate of 0.1mA/cm²A planar high resolution image of 200s was deposited at a current density of (1).

FIG. 7 shows the plating solution of the present invention at 0.1mA/cm²A flat high resolution image of 300s was deposited at a current density of (a).

FIG. 8 shows the plating solution of the present invention at a rate of 0.1mA/cm²A planar high resolution image of 500s was deposited at a current density of (a).

FIG. 9 shows the plating solution of the present invention at a rate of 0.1mA/cm²A planar high resolution image of 600s was deposited at a current density of (a).

FIG. 10 is a graph of R6G10 detection after different times of constant current density deposition in accordance with the present invention^-6SERS spectrum of M.

FIG. 11 shows SERS spectra of different R6G concentrations detected during constant current density deposition for 400s according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the following description, taken in conjunction with the accompanying drawings, provides specific embodiments of the present invention, which is based on the application of the controllable electroplating method for V-cavity array surface in the preparation of the high-sensitivity SERS substrate. Of course, the specific examples described herein are merely illustrative of the invention and are not intended to be limiting.

Example 1

The invention discloses a method for using a V-shaped thin electro-silver film as an electric template (see figure 2), which comprises the following steps:

1) the AAO template with the aperture of V-type 450-100 is adopted, the upper end of the aperture is a hexagonal hole with the aperture of 450nm, the bottom is a circular pocket bottom with the aperture of 100nm, and the depth of the hole is 400 nm. Ultrasonically cleaning in deionized water, ethanol, acetone and deionized water for 10 minutes according to the steps, cleaning the surface and the holes of the AAO template, and then blowing the AAO template by nitrogen for later use.

2) Firstly, a layer of metal chromium with the thickness of 10nm is evaporated on the surface of the AAO by using a vacuum film plating machine, so that a subsequently evaporated silver film is uniformly and tightly combined with the AAO.

3) And (3) evaporating a 120nm silver film at a constant rate of 0.2 angstrom/second, and finally forming an AAO electroplating template covered by the silver film, wherein the average value of the hole wall thickness is 60nm, the upper end of the hole diameter is a hexagonal hole with the diameter of 360nm, the bottom of the hole diameter is a circular pocket bottom with the diameter of 100nm, and the depth of the hole is 400nm, as shown in figure 2.

Example 2

The invention discloses a method for preparing a high-performance uniform SERS substrate by directionally and controllably assembling electrodeposited gold nanoparticles, which comprises the following steps of:

1) preparing electroplating solution, preparing a mixed solution of 3.3mM chloroauric acid and 0.1M hydrofluoric acid, wherein the used water is EW-I standard deionized water.

2) Adopting a three-electrode electrochemical workstation, taking an electroplating template as a working electrode, taking a platinum sheet electrode as a counter electrode, and taking Ag/AgCl₂As a reference electrode, at 0.1mA/cm²The different shapes and SERS performances are obtained by depositing the particles at different times under the current density.

3) Referring to fig. 3-9, the deposition growth process is detailed for different profiles of deposition 100s-600s, respectively.

4) SERS detection is carried out aiming at different morphologies, and R6G10 is used^-6For example, referring to fig. 10, the deposition time of 400s is found to be the optimum profile, and the SERS intensity is significantly higher than for samples with other profiles.

The invention reports a method for assembling gold nanoparticles by directional controllable electrodeposition, and a funnel-type cascade structure with nanoscale gaps (less than 10nm) can be formed and is uniform and controllable, the appearance has a large number of nanoscale gaps, and the funnel-type cascade structure is provided with a uniform and regular three-dimensional funnel cavity, the gold nanoparticles with nanoscale gaps are assembled in the funnel cavity, and the adsorption capacity on probe molecules is greatly enhanced by the rough-surface cascade structure and the concave-convex cascade cavity wall. The unique structure not only forms an electromagnetic field with high intensity and enhances the SERS excitation efficiency, but also provides a large number of molecular binding sites with the detection limit as low as 10^-18The R6G concentration of M (see figure 11) can realize single-molecule detection, and the developed low-cost, high-performance and high-sensitivity solid membrane substrate has great significance in SERS detection.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and decorations can be made for different situations without departing from the manufacturing method of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.