CN113308685B - A kind of silver nanometer/foam copper material and its preparation method and application - Google Patents

Abstract

The invention discloses a preparation method of an SERS substrate made of silver nano/foamy copper materials. The SERS substrate made of the silver nano/copper foam material is low in material cost, simple in preparation method, high in stability, storage-resistant and high in sensitivity in Raman detection.

Description

A kind of silver nanometer/foamed copper material and its preparation method and application

technical field

The invention belongs to the technical field of surface-enhanced Raman scattering spectroscopy, and in particular relates to a silver nanometer/foamed copper material and a preparation method and application thereof.

Background technique

Copper foam is a new multi-functional material with a large number of connected or disconnected holes evenly distributed in the copper matrix. It has good electrical conductivity and ductility. Compared with similar materials, nickel foam has lower preparation cost and better electrical conductivity. , so it is often used to prepare battery anode (carrier) materials, catalyst carriers and electromagnetic shielding materials.

Surface-enhanced Raman spectroscopy (SERS) is a technique that uses the enhanced electric field on the metal surface to increase the intensity of the Raman spectrum by adsorbing the molecules to be measured by noble metals. Due to its high sensitivity and rapid detection, it has been widely used in many fields such as chemistry, biopharmaceuticals, medical testing and food safety. At present, the enhancement mechanisms of SERS generally recognized by the academic community mainly include electromagnetic field enhancement mechanism (EM) and charge transfer enhancement mechanism (CT). Electromagnetic field enhancement mechanism (EM) believes that when light is incident on the surface of the SERS substrate, the nanostructures on the surface of the substrate will be excited to generate localized surface plasmons, and the phenomenon of localized surface plasmon resonance will occur, which makes the molecules to be measured pull. The Mann signal is greatly enhanced; another charge transfer enhancement mechanism (CT) believes that when the metal surface is irradiated with light, electron transfer occurs between the molecules to be tested adsorbed on the metal surface and the metal, resulting in resonance-like Raman Scattering phenomenon, which enhances the Raman signal of the molecule to be tested.

Traditional SERS substrate materials mainly include metal materials, semiconductor materials and metal/semiconductor composite materials. Among them, the surface plasmon resonance of precious metal silver can effectively and quickly enhance the regional electromagnetic field on the metal surface, and can adsorb more molecules to be tested under the nanostructure, so it is often used for surface-enhanced Raman spectroscopy (SERS) detection . For example, Chinese patent document CN112630151A proposes a silver sol SERS substrate suitable for organophosphorus and carbamate sulfur-containing pesticide molecules, which reduces the lower limit of Raman detection; The number of hot spots is not good enough, and the enhancement effect needs to be further improved. Another example is the Chinese patent document CN108893714B, which specifically proposes a SERS substrate with a dense Ag nano-columnar structure, which increases the number of "hot spots" of the substrate through the nano-column structure, and enhances the enhancement effect of the substrate; but the silver nanostructure is easily affected during the detection process. Oxidation or pollution of the molecule to be tested or the detection environment, poor stability and limited storage time. The above disclosed methods all use a substrate made of silver nanomaterials for surface enhancement of Raman spectroscopy, but they are lacking in the protection of nanostructures, and at the same time, the adsorption of the molecules to be tested and the number of "hot spots" still need further work. Research.

SUMMARY OF THE INVENTION

In order to solve the deficiencies of the above problems in the prior art, the purpose of the present invention is to provide a silver nano/copper foam material and a preparation method and application thereof. The preparation method adopts a foamed copper structure as a frame to improve the stability of the substrate and prolong At the same time, the prepared silver nano/copper foam material is used as the SERS substrate to increase the adsorption capacity of the molecules to be tested, increase the detection "hot spot" of the substrate, significantly improve the sensitivity of the substrate, and reduce the detection limit.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of silver nano/foamed copper material, comprising the following steps:

(1) Hydrochloric acid soaking of the foamed copper sheet: Immerse the cleaned and dried foamed copper sheet in a dilute hydrochloric acid solution for a period of time;

(2) surface impurity removal of foamed copper sheet: use absolute ethanol and deionized water successively to rinse the foamed copper sheet after soaking in step (1) to remove impurities on the surface of foamed copper sheet;

(3) preparation of mixed solution: fully mix silver nitrate solution and PVP solution to obtain mixed solution;

(4) oscillating reaction: the foamed copper sheet after surface impurity removal in step (2) is immersed in the mixed solution obtained in step (3), and the oscillating reaction is carried out for a period of time;

(5) Post-reaction treatment: rinse the foamed copper sheet after shaking reaction in step (4) with absolute ethanol and deionized water in turn, and then dry to obtain silver nanometer/foamed copper material.

Preferably, in step (1), the mass fraction of the dilute hydrochloric acid solution is 3.6%, the dosage is 15 mL, and the soaking time is 10 min.

Preferably, in step (3), the concentration of the silver nitrate solution is 0.1-1 mol/L, and the concentration of the PVP solution is 0.05 g/mL.

Preferably, in step (3), the volume dosage ratio of the silver nitrate solution to the PVP solution is 1:0.01-0.5.

Preferably, the oscillation reaction time in step (4) is 10s˜50s.

Preferably, in step (5), the drying temperature is 60° C., and the drying time is 2 h.

Still further preferably, in step (3), the concentration of silver nitrate solution is 0.8mol/L.

Still further preferably, the oscillation reaction time in step (4) is 40s.

At the same time, the present invention also claims to protect the silver nano/foamed copper material prepared by the above method.

At the same time, the present invention also claims to protect the application of the above-mentioned silver nano/foamed copper material as a SERS substrate.

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

(1) The present invention creatively proposes to prepare the silver nano/foamed copper material by using foamed copper as the main frame. By virtue of the three-dimensional structure of the foamed copper material, the silver nanometer/foamed copper material can absorb more molecules to be tested and more There are many Raman "hot spots", which can greatly promote Raman enhancement, thereby improving the sensitivity of SERS detection.

(2) The silver nanometer/foamed copper material prepared by the present invention uses the porous rigid structure of the foamed copper as the shell to provide protection for the inner silver nanostructure, greatly improving the durability and stability of the SERS substrate and prolonging the durability of the substrate. Storage time limit.

(3) The silver nanometer/foamed copper material prepared by the present invention uses a lower cost foamed copper material, and the whole preparation process is simple, fast and easy to master, no high-end preparation equipment is required, and the preparation cost is greatly reduced.

(4) The present invention unexpectedly finds that the concentration of silver nitrate solution and the shaking time have a significant impact on the performance of the prepared silver nano/copper foam material, and better process parameters are obtained.

Description of drawings

FIG. 1 is an SEM image of 0.1M/LAgNO ₃ forming a silver nano/foamed copper substrate in Example 1 of the present invention.

FIG. 2 is a SEM image of 0.2M/LAgNO ₃ forming a silver nano/foamed copper substrate in Example 2 of the present invention.

FIG. 3 is a SEM image of 0.4M/LAgNO ₃ forming a silver nano/foamed copper substrate in Example 3 of the present invention.

4 is a SEM image of 0.8M/LAgNO ₃ forming a silver nano/foamed copper substrate in Example 4 of the present invention.

FIG. 5 is a SEM image of 1.6M/LAgNO ₃ forming a silver nano/foamed copper substrate in Example 5 of the present invention.

6 is a Raman spectrum diagram of low-concentration 4-ATP probe molecules measured by using AgNO ₃ solutions of different concentrations to prepare silver nano/foamed copper substrates in the embodiment of the present invention.

7 is a linear diagram of the strongest characteristic peaks of low-concentration 4-ATP probe molecules measured by AgNO ₃ solutions with different concentrations in the embodiment of the present invention obtained from silver nano/foamed copper substrates.

FIG. 8 is a SEM image of the silver nano/foamed copper substrate formed by the shaking time of 10s in Example 6 of the present invention.

FIG. 9 is a SEM image of forming a silver nano/foamed copper substrate with an oscillation time of 20s in Example 7 of the present invention.

FIG. 10 is a SEM image of the silver nano/foamed copper substrate formed by shaking for 30 s in Example 8 of the present invention.

FIG. 11 is a SEM image of the silver nano/foamed copper substrate formed by the shaking time of 40s in Example 9 of the present invention.

FIG. 12 is a SEM image of the silver nano/foamed copper substrate formed by shaking for 50 s in Example 10 of the present invention.

FIG. 13 is a Raman spectrum diagram of low-concentration 4-ATP probe molecules measured by silver nano/foamed copper substrates prepared with different shaking times in Examples 6 to 10 of the present invention.

14 is a linear diagram of the strongest characteristic peaks of low-concentration 4-ATP probe molecules measured by silver nano/foamed copper substrates prepared with different shaking times in Examples 6 to 10 of the present invention.

Detailed ways

In order to make the invention purpose, technical solutions and invention advantages of the present invention more clearly described, the present invention will be further explained in detail below with reference to the embodiments of the description and the accompanying drawings.

Unless otherwise specified, the chemical reagents used in the present invention are purchased through commercial channels. Among them, the thickness of the foam copper sheet used in each embodiment of the present invention is 0.5mm, and the purity is 99.9%; dilute hydrochloric acid, ethanol, silver nitrate (AgNO ₃ , purity 99.9%), PVP (polyvinylpyrrolidone), 4-amino sulfur Phenol (4-ATP, ≥90% purity) were all analytical grade reagents without further purification, and the water used was deionized water.

Example 1

A preparation method of silver nano/foamed copper material, comprising the following steps:

(1) Hydrochloric acid soaking of the foamed copper sheet: Immerse the cleaned and dried foamed copper sheet with a size of 0.5cm*0.5cm*0.5mm in 15mL of a dilute hydrochloric acid solution with a mass fraction of 3.6% for 10min;

(2) surface impurity removal of foamed copper sheet: use absolute ethanol and deionized water successively to rinse the foamed copper sheet after soaking in step (1) to remove impurities on the surface of foamed copper sheet;

(3) preparation of mixed solution: fully mix 10 mL of silver nitrate solution with a concentration of 0.1 mol/L and 2 mL of PVP solution of 0.05 g/mL to obtain a mixed solution;

(4) Vibration reaction: immerse the foamed copper sheet after surface impurity removal in step (2) in the mixed solution obtained in step (3), and vibrate for 30s;

(5) Post-reaction treatment: wash the foamed copper sheet after shaking reaction in step (4) with absolute ethanol and deionized water in turn, then put it into a vacuum drying box, and dry it at 60 ° C for 2 hours to obtain silver nano/ Foam copper material.

Examples 2 to 5

Except for the different concentrations of the silver nitrate solutions, the process conditions and preparation processes of Examples 2 to 5 are the same as those of Example 1. The concentrations of the silver nitrate solutions in Examples 2 to 5 were 0.2 mol/L, 0.4 mol/L, 0.8 mol/L, and 1.6 mol/L, respectively.

Figures 1 to 5 are the SEM images of the silver nano/copper foam materials prepared in Examples 1 to 5, respectively. It can be seen from Figures 1 to 5 that as the concentration of AgNO ₃ is higher, the silver nanoparticles are on the surface of the copper foam. The deposition effect first increased and then decreased.

At the same time, the present invention uses 10-4 mol/L ⁴ -ATP as a probe molecule to test and analyze the SERS enhancement effect of the silver nanometer/foamed copper substrate prepared in Examples 1 to 5. The test method is as follows:

(1) Cut the dry and clean silver nano/foamed copper material into small pieces of suitable specifications as the substrate.

(2) Add 10-4 mol/L ⁴ -ATP probe molecule solution dropwise on the substrate to ensure that the substrate is fully immersed, and stand at room temperature for 20 minutes.

(3) Put the standing substrate into a vacuum drying oven, and dry it at 60° C. for 6 hours.

(4) Raman spectroscopy test was performed on the dried sample.

The test results are shown in Figure 6 and Figure 7. Combining Fig. 6 and Fig. 7, it can be seen that when the AgNO ₃ concentration is 0.8 mol/L, the SERS enhancement effect of the silver nano/copper foam substrate is the best.

Example 6

A preparation method of silver nano/foamed copper material, comprising the following steps:

(1) Hydrochloric acid soaking of the foamed copper sheet: Immerse the cleaned and dried foamed copper sheet with a size of 0.5cm*0.5cm*0.5mm in 15mL of a dilute hydrochloric acid solution with a mass fraction of 3.6% for 10min;

(2) surface impurity removal of foamed copper sheet: use absolute ethanol and deionized water successively to rinse the foamed copper sheet after soaking in step (1) to remove impurities on the surface of foamed copper sheet;

(3) preparation of mixed solution: 10mL concentration is that the silver nitrate solution of 0.8mol/L is fully mixed with the PVP solution of 2mL 0.05g/mL, obtains mixed solution;

(4) Vibration reaction: immerse the foamed copper sheet after surface impurity removal in step (2) in the mixed solution obtained in step (3), and vibrate for 10s;

(5) Post-reaction treatment: wash the foamed copper sheet after shaking reaction in step (4) with absolute ethanol and deionized water in turn, then put it into a vacuum drying box, and dry it at 60 ° C for 2 hours to obtain silver nano/ Foam copper material.

Examples 7-10

Except for the shaking time, the process conditions and preparation process of Examples 7-10 are the same as those of Example 6. Wherein, the shaking times in Examples 7-10 were 20s, 30s, 40s, and 50s, respectively.

Figures 8 to 12 are the SEM images of the silver nano/copper foam materials prepared in Examples 6 to 10. It can be seen from the figures that with the gradual increase of the oscillation time, the deposition effect of silver nanoparticles on the surface of the foamed copper is the same. showed an increase first and then a decrease.

At the same time, the present invention uses 10-4 mol/L ⁴ -ATP as a probe molecule to test and analyze the SERS enhancement effect of the silver nanometer/foamed copper substrate prepared in Examples 6-10. The test method is as follows:

(1) Cut the dry and clean silver nano/foamed copper material into small pieces of suitable specifications as the substrate.

(2) Add 10-4 mol/L ⁴ -ATP probe molecule solution dropwise on the substrate to ensure that the substrate is fully immersed, and stand at room temperature for 20 minutes.

(3) Put the standing substrate into a vacuum drying oven, and dry it at 60° C. for 6 hours.

(4) Raman spectroscopy test was performed on the dried sample.

The test results are shown in Figure 13 and Figure 14. Combining Figure 13 and Figure 14, it can be seen that when the oscillation time is 40s, the SERS enhancement effect of the silver nano/copper foam substrate is the best.

The above description describes preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the claims of the present invention. Any modifications, equivalent replacements and improvements without departing from the principles and ideas of the present invention shall be deemed to be within the protection scope of the claims of the present invention.

Claims (6)

1. the application of a silver nanometer/foamed copper material as a SERS substrate, is characterized in that, the preparation of described silver nanometer/foamed copper material comprises the steps: (1) Hydrochloric acid soaking of the foamed copper sheet: Immerse the cleaned and dried foamed copper sheet in a dilute hydrochloric acid solution for a period of time; (2) surface impurity removal of foamed copper sheet: use absolute ethanol and deionized water successively to rinse the foamed copper sheet after soaking in step (1) to remove impurities on the surface of foamed copper sheet; (3) preparation of mixed solution: fully mix silver nitrate solution and PVP solution to obtain mixed solution; (4) oscillating reaction: the foamed copper sheet after surface impurity removal in step (2) is immersed in the mixed solution obtained in step (3), and the oscillating reaction is carried out for a period of time; (5) post-reaction treatment: successively rinse the foamed copper sheet after the oscillation reaction in step (4) with absolute ethanol and deionized water, and then dry to obtain silver nano/foamed copper material; Wherein, in step (3), the concentration of silver nitrate solution is 0.8mol/L; Wherein, the oscillation reaction time in step (4) is 40s. 2. the application of a kind of silver nanometer/foamed copper material as SERS substrate according to claim 1, is characterized in that, in step (1), the mass fraction of dilute hydrochloric acid solution is 3.6%, the consumption is 15mL, and the soaking time is 10min. 3. the application of a kind of silver nanometer/foamed copper material as SERS substrate according to claim 1, is characterized in that, in step (3), the concentration of PVP solution is 0.05g/mL. 4. the application of a kind of silver nanometer/foamed copper material as SERS substrate according to claim 3, is characterized in that, in step (3), the volume dosage ratio of silver nitrate solution and PVP solution is 1:0.01～0.5. 5 . The application of a silver nano/foamed copper material as a SERS substrate according to claim 4 , wherein the oscillation reaction time in step (4) is 10s˜50s. 6 . 6 . The application of the silver nanometer/foamed copper material according to any one of claims 1 to 5 as a SERS substrate, wherein the drying temperature in step (5) is 60° C. and the drying time is 2 h.

Images