阅读说明：本技术 一种表面具有增强拉曼信号功能的纳米多孔银基衬底的制备方法 (Preparation method of nano-porous silver-based substrate with surface having Raman signal enhancing function ) 是由 张启波 雷浩 于 2021-01-05 设计创作，主要内容包括：本发明公开了一种表面具有增强拉曼信号功能的纳米多孔银基衬底的制备方法,属于材料制备技术领域,包括以下步骤：对银基底表面进行前处理后,浸泡在碱性溶液中,采用电化学氧化还原法,在基底表面制备得到所述纳米多孔银基衬底；本发明将银基底加入到碱性溶液中,通过控制电化学氧化还原电位,实现金属银的原位氧化和还原；利用氧化银和金属银的晶格大小差异,在银基底表面得到均匀、稳定的纳米多孔结构,从而能够有效增强拉曼信号；该方法制备纳米多孔银基衬底材料具有操作方法简单,反应条件温和、可控,原料廉价易得,反应能耗低,且无需任何添加剂、无污染,产品质量稳定,易于规模化生产等优势。(The invention discloses a preparation method of a nano-porous silver-based substrate with a surface having a function of enhancing Raman signals, belonging to the technical field of material preparation and comprising the following steps: pretreating the surface of a silver substrate, soaking the silver substrate in an alkaline solution, and preparing the nano porous silver-based substrate on the surface of the substrate by adopting an electrochemical oxidation-reduction method; the method comprises the steps of adding a silver substrate into an alkaline solution, and realizing in-situ oxidation and reduction of metallic silver by controlling electrochemical oxidation-reduction potential; by utilizing the difference of the lattice sizes of the silver oxide and the metallic silver, a uniform and stable nano porous structure is obtained on the surface of the silver substrate, so that a Raman signal can be effectively enhanced; the method for preparing the nano porous silver-based substrate material has the advantages of simple operation method, mild and controllable reaction conditions, cheap and easily-obtained raw materials, low reaction energy consumption, no need of any additive, no pollution, stable product quality, easiness in large-scale production and the like.)

1. A preparation method of a nano-porous silver-based substrate with a surface having a Raman signal enhancing function is characterized by comprising the following steps:

and (2) pretreating the surface of the silver substrate, soaking the silver substrate in an alkaline solution, and preparing the nano porous silver substrate by adopting an electrochemical oxidation-reduction method.

2. The method of claim 1, wherein the silver substrate is silver foam, silver flakes, silver wire, or silver alloy.

3. The preparation method according to claim 1, wherein the pretreatment is carried out by ultrasonic treatment of the silver substrate with hydrochloric acid, ultrasonic treatment with absolute ethyl alcohol and then washing with deionized water.

4. The method according to claim 1, wherein the pH of the alkaline solution is 9 or more.

5. The method of claim 1, wherein the electrochemical redox method is linear voltammetry, cyclic voltammetry, or chronoamperometry.

6. The method according to claim 5, wherein the linear voltammetric sweep is performed by forward sweeping 10 times in the range of 0-1.5V vs. RHE, and then backward sweeping 15 times in the range of 0-1.5V vs. RHE; the cyclic voltammetry is specifically scanned for 15 times within the range of 0-1.5V vs. RHE; the ampere timing method specifically comprises the steps of firstly working for 2000s under the voltage of 1.5V vs. RHE; then the operation is carried out for 3000s under the voltage of 0.6V vs. RHE.

7. The preparation method according to claim 1, wherein the temperature of the electrochemical oxidation-reduction is 273-373K.

8. The method according to claim 1, further comprising the steps of rinsing and drying the nanoporous silver-based substrate with acetone, deionized water.

9. The method of claim 8, wherein the drying is vacuum drying.

Technical Field

The invention belongs to the technical field of material preparation, and particularly relates to a preparation method of a nano porous silver-based substrate with a surface having a Raman signal enhancing function.

Background

Trace molecular detection has been widely used in environmental monitoring, food safety, disease detection, cell detection and forensic identification. However, the detection of trace molecules is difficult to realize, and the problems of high technical difficulty, high detection cost, low detection speed, low detection efficiency, low repeatability and the like exist. The Surface Enhanced Raman Scattering (SERS) technology is applied to physical property detection and trace molecule detection, and has low detection limit and abundant molecular structure information. Some metallic nanostructure materials have strong Local Surface Plasmon Resonance (LSPR) properties in the visible and near infrared bands, which can locally apply optical field energy to the surface of the metallic structure and enhance the intensity of the surrounding electric field, thereby significantly improving the spectral signal intensity of the surrounding optical material. Studies have demonstrated that silver nanoparticles have higher plasmon resonance activity compared to noble metal materials such as gold and copper, which makes silver one of the most commonly used materials in biochemical sensing applications. The LSPR characteristics of nanoparticles are greatly affected by surface morphology, particle size, and surrounding medium. The tuning of the particle LSPR characteristics can be achieved by varying the above parameters. Therefore, the preparation of silver nanoparticles with controlled morphology and particle size has been a focus of research.

The preparation method of the silver nanoparticles can be divided into physical preparation and chemical preparation according to different principles in the preparation process. The principle of the physical preparation method is as follows: the bulk metal material is dispersed into nano-sized particles under the action of force by applying certain physical force such as heat, gas, force and the like to the bulk metal material. Currently, common physical preparation methods include magnetron sputtering and evaporative condensation. The preparation principle of the chemical method is that silver ions in the silver-containing metal compound are reduced through chemical reaction, and finally zero-valent silver atoms are formed, so that the synthesis and preparation of the silver nanoparticles are completed. Common chemical methods include chemical reduction, thermal decomposition, electrochemical reduction, and photoreduction. However, these methods typically require high temperature, high pressure, strong acid, strong base environments. In addition, the preparation processes not only need the assistance of large-scale equipment, but also are complicated, are not beneficial to large-scale production, have high energy consumption and large pollution, and are extremely unfavorable for the environment.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of a nano-porous silver-based substrate with a surface having a function of enhancing Raman signals.

The invention provides the following technical scheme:

a preparation method of a nano-porous silver-based substrate with a surface having a Raman signal enhancing function comprises the following steps:

and (2) pretreating the surface of the silver substrate, soaking the silver substrate in an alkaline solution, and preparing the nano porous silver substrate by adopting an electrochemical oxidation-reduction method.

Further, the silver substrate is foamed silver, silver flakes, silver wires or silver alloy.

Furthermore, the silver content in the silver alloy is more than or equal to 30 wt%.

Further, the specific pretreatment method comprises the step of washing the silver substrate with deionized water after hydrochloric acid ultrasonic treatment and absolute ethyl alcohol ultrasonic treatment.

Further, the pH value of the alkaline solution is more than or equal to 9.

Further, the electrochemical redox method is linear voltammetry, cyclic voltammetry or chronoamperometry.

Further, the linear voltammetry scanning method comprises the steps of firstly carrying out forward scanning for 10 times in a range of 0-1.5V vs. RHE, and then carrying out reverse scanning for 15 times in a range of 0-1.5V vs. RHE; the cyclic voltammetry is specifically scanned for 15 times within the range of 0-1.5V vs. RHE; the ampere timing method specifically comprises the steps of firstly working for 2000s under the voltage of 1.5V vs. RHE; then the operation is carried out for 3000s under the voltage of 0.6V vs. RHE.

Furthermore, the temperature of the electrochemical oxidation reduction is 273-373K.

Further, the method also comprises the step of washing and drying the nano-porous silver-based substrate by adopting ethanol and deionized water.

Further, the drying is vacuum drying.

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

(1) the method comprises the steps of adding a silver substrate into an alkaline solution, and realizing in-situ oxidation and reduction of metallic silver by controlling electrochemical oxidation-reduction potential; by utilizing the difference of the lattice sizes of the silver oxide and the metallic silver, a uniform and stable nano porous structure is obtained on the surface of the silver substrate, so that a Raman signal can be effectively enhanced.

(2) The method for preparing the nano-porous silver-based substrate material with the surface having the function of enhancing the Raman signal is simple, the reaction condition is mild and controllable, the raw materials are cheap and easy to obtain, the reaction energy consumption is low, no additive is needed, no pollution is caused, the product quality is stable, and the large-scale production is easy.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a microstructure diagram of the clean and smooth silver substrate obtained in example 1 and the finally prepared nano-porous silver-based substrate material with the function of enhancing raman signal, wherein fig. 1a is a microstructure diagram of the clean and smooth silver substrate, and fig. 1b is a microstructure diagram of the nano-porous silver-based substrate with the function of enhancing raman signal.

FIG. 2 is 10^-2Raman spectra of mol/L Sudan Red on clean, smooth silver substrate obtained in example 1 and 10^-7Raman spectra of mol/L sudan red on nanoporous silver-based substrates finally prepared in example 1.

FIG. 3a is a Raman enhancement spectrum of different concentrations of R6G on the nanoporous silver-based substrate prepared in example 1, and FIG. 3b is a spectrum of 1645cm^-1Plot of raman signal intensity near peak versus R6G concentration.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

In the following examples, electrochemical redox was carried out in a three-electrode system, using a silver substrate immersed in an alkaline solution as the working electrode and a platinum column as the reference electrode (Φ 1 mm; area 0.314 cm)²) Ag/AgCl as a reference electrode;

in the following examples, the linear voltammetry scan is specifically performed by forward scanning 10 times in the range of 0-1.5V vs. rhe, and then reverse scanning 15 times in the range of 0-1.5V vs. rhe; the cyclic voltammetry is specifically scanned for 15 times within the range of 0-1.5V vs. RHE; the ampere timing method specifically comprises the steps of firstly working for 2000s under the voltage of 1.5V vs. RHE; then working for 3000s under the voltage of 0.6V vs. RHE;

the description will not be repeated below.

Example 1

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on a silver sheet (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and ultrasonic treatment on absolute ethyl alcohol, repeatedly washing the silver sheet by deionized water for 5 times to obtain a clean and smooth silver sheet, then soaking the silver sheet in a potassium hydroxide solution with the pH of 9, carrying out in-situ electrochemical oxidation reduction by a Linear Scanning Voltammetry (LSV) at 273K, taking out the silver sheet after reaction, washing the silver sheet by acetone and distilled water, and drying the silver sheet in a vacuum drying oven.

Example 2

Preparing a nano porous silver substrate with the surface having the function of enhancing Raman signals:

carrying out ultrasonic treatment on foamed silver (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the foamed silver by deionized water for 10 times, soaking the foamed silver in a sodium hydroxide solution with the pH value of 13, carrying out in-situ electrochemical oxidation reduction by a Linear Scanning Voltammetry (LSV) at 373K, taking out the reacted foamed silver, washing the reacted foamed silver by acetone and distilled water, and drying the washed foamed silver in a vacuum drying oven.

Example 3

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on silver wires (phi is 1mm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the silver wires by deionized water for 8 times, soaking the silver wires in a sodium hydroxide solution with the pH value of 11, carrying out LSV (local surface plasmon resonance) in-situ electrochemical oxidation reduction at 300K, taking out the silver wires after reaction, washing the silver wires by acetone and distilled water, and drying the silver wires in a vacuum drying oven.

Example 4

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on a silver alloy (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the silver alloy by deionized water for 6 times, soaking the silver alloy in a potassium hydroxide solution with the pH value of 13, carrying out in-situ electrochemical oxidation reduction by a Cyclic Voltammetry (CV) at 350K, taking out the silver alloy after reaction, washing the silver alloy by acetone and distilled water, and drying the silver alloy in a vacuum drying oven.

Example 5

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on a silver sheet (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the silver sheet with deionized water for 7 times, soaking the silver sheet in a sodium hydroxide solution with the pH value of 13, carrying out in-situ electrochemical oxidation reduction by a chronoamperometric (i-t) method at 373K, taking out the silver sheet after reaction, washing the silver sheet with acetone and distilled water, and drying the silver sheet in a vacuum drying oven.

Example 6

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on a silver sheet (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the silver sheet with deionized water for 7 times, soaking the silver sheet in a quick lime solution with the pH value of 10, carrying out in-situ electrochemical oxidation reduction by an i-t method at 373K, taking out the silver sheet after reaction, washing the silver sheet with acetone and distilled water, and drying the silver sheet in a vacuum drying oven.

Example 7

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

carrying out ultrasonic treatment on a silver sheet (0.5cm multiplied by 0.06cm) by dilute hydrochloric acid and absolute ethyl alcohol, repeatedly washing the silver sheet with deionized water for 7 times, soaking the silver sheet in a barium hydroxide solution with the pH value of 13, carrying out in-situ electrochemical oxidation reduction by an i-t method at 373K, taking out the silver sheet after reaction, washing the silver sheet with acetone and distilled water, and drying the silver sheet in a vacuum drying oven.

Example 8

The preparation of the nano-porous silver-based substrate with the surface having the function of enhancing Raman signals comprises the following steps:

subjecting silver sheet (0.5cm × 0.5cm × 0.06cm) to dilute hydrochloric acid ultrasonic treatment and anhydrous ethanol ultrasonic treatment, repeatedly washing with deionized water for 7 times, soaking in disodium hydrogen phosphate solution with pH of 9, performing in-situ electrochemical oxidation-reduction by i-t method at 373K, washing the silver sheet with acetone and distilled water, and drying in vacuum drying oven to obtain the final product

Comparative example 1

The difference from example 1 is that the temperature of the electrochemical redox was changed from 273K to 250K.

Comparative example 2

The difference from example 1 is that the linear voltammetric sweep was performed by first 10 forward sweeps in the range of 0-2.5V vs. RHE and then 15 reverse sweeps in the range of 0-2.5V vs. RHE.

Comparative example 3

The difference from example 1 is that the potassium hydroxide solution at pH 13 is replaced by a potassium hydroxide solution at pH 8.

Comparative example 4

The difference from example 1 is that the parameters of the linear sweep voltammetry were modified to a multi-turn CV scan.

Effect test example 1

The microstructure of the clean and smooth silver substrate obtained in example 1 and the finally prepared nanoporous silver-based substrate with the raman signal enhancement function on the surface is observed, as shown in fig. 1, where fig. 1a is a microstructure diagram of the clean and smooth silver substrate, and fig. 1b is a microstructure diagram of the nanoporous silver-based substrate with the raman signal enhancement function. As can be seen from fig. 1, a uniform nanoporous structure can be formed on the surface of the silver substrate by using the method of the present invention.

The microstructure of the nano-porous silver-based substrate with the surface having the function of enhancing raman signal prepared in examples 2 to 8 was observed, and it was found that the surface thereof also formed a uniform nano-porous structure as in example 1.

Effect test example 2

The clean and smooth silver substrate obtained in example 1 and the finally prepared nano-porous silver-based substrate with the function of enhancing raman signal were respectively immersed in 10^-2mol/L、10^-7After 30min in mol/L Sudan red (R6G), taking out, washing and airing, researching the SERS phenomenon of Sudan red molecules adsorbed on the material, carrying out surface enhanced Raman spectroscopy test by using an RM-1000 type confocal micro laser Raman spectrometer, adopting a laser source with the excitation wavelength of 515nm, carrying out an objective lens 50X, wherein the laser power vertically incident to the surface of the sample is about 5mW, and the SERS spectrum is shown in figure 2. As can be seen from figure 2, the nano porous silver-based substrate prepared by the invention has the concentration as low as 10^-7The Sudan red of mol/L has good Raman signal enhancement function.

The results of the effectiveness verification of the nanoporous silver-based substrates with the raman signal enhancement function prepared in examples 2 to 8 were the same as example 1.

The effect of the material prepared in comparative examples 1 to 4 was verified by the above method, and it was found that the raman signal enhancement function was inferior to that of examples 1 to 8.

Effect test example 3

The nanoporous silver-based substrates with the function of enhancing raman signal prepared in example 1 were respectively soaked in 10^-6mol/L、10^-7mol/L、10^-8mol/L、10^-9Taking out, washing and airing the Sudan red (R6G) of mol/L for 30min, and researching the SERS phenomenon of Sudan red molecules adsorbed on the material, wherein the surface enhanced Raman spectrum is tested by using an RM-1000 type confocal micro laser Raman spectrometer, a laser source with the excitation wavelength of 515nm and an objective lens 50X are adopted, the laser power vertically incident to the surface of the sample is about 5mW, and the SERS spectrum is shown in figure 3, wherein figure 3a is a surface enhanced Raman spectrum diagram of R6G with different concentrations, and figure 3b is 1645cm in the spectrum^-1Plot of raman signal intensity near peak versus R6G concentration.

The results of the effectiveness verification of the nanoporous silver-based substrates with the raman signal enhancement function prepared in examples 2 to 8 were the same as example 1.

The effect of the material prepared in comparative examples 1 to 4 was verified by the above method, and it was found that the raman signal enhancement function was inferior to that of examples 1 to 8.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.