Preparation method of rose-shaped silver powder with raman enhancement effect and application thereof

Abstract

The application discloses a preparation method of a rose-shaped silver powder with a Raman enhancement effect, and comprises the following steps: (1) preparing a silver nitrate solution, then adding aminoacetic acid into the silver nitrate solution to dissolve sufficiently to obtain a precursor solution; (2) preparing a reducing agent solution; then adding a dispersing agent and a buffer pair into the reducing agent solution to stir uniformly under heating to obtain a mixed solution of the reducing agent, the dispersing agent and the buffer pair; (3) under a light-proof environment at 22-26 DEG C, the precursor solution is added dropwise into the mixed solution of the reducing agent, the dispersing agent and the buffer pair while stirring, and after titration, the reaction is continued to obtain a silver colloid solution; and (4) the silver colloid solution is subjected to centrifugal separation, washing and drying in sequence to obtain the rose-shaped silver powder. The application has the advantages of simplicity, high efficiency, low cost and a large process window, and is beneficial to subsequent commercial mass production.

Description

Technical Field

[0001] This invention belongs to the field of conductive material preparation technology, specifically relating to a method for preparing rose-shaped silver powder with Raman enhancement effect and its application. Background Technology

[0002] In 1974, Fleischmann et al. discovered a significant enhancement in the Raman signal intensity of pyridine molecules on a rough silver electrode surface, leading to the development of surface-enhanced Raman scattering (SERS) technology. Due to its high resolution and sensitivity, SERS has broad application prospects in solid surface chemistry and trace analysis. Among metals exhibiting SERS, silver has been found to show the best enhancement effect.

[0003] Currently, liquid-phase chemical reduction is commonly used to prepare micro- and nano-scale flower-like silver powder. However, most reaction systems have drawbacks such as complicated process flow, environmental unfriendliness, high energy consumption, poor reproducibility, and unstable morphology and size of the prepared flower-like silver powder. Therefore, a simple, green, energy-saving, low-cost, and highly reproducible method for preparing flower-like silver powder is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a method for preparing rose-shaped silver powder with Raman enhancement effect.

[0005] Another object of the present invention is to provide the application of the rose-shaped silver powder obtained by the above preparation method.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing rose-shaped silver powder with Raman enhancement effect includes the following steps:

[0008] (1) Prepare a silver nitrate solution, then add glycine (Gly) to the silver nitrate solution and dissolve it completely to obtain a precursor solution;

[0009] (2) Prepare a reducing agent solution; then mix the dispersant, buffer pair and reducing agent in deionized water and heat to 58-62℃ and stir evenly, then cool to 22-26℃ to obtain a mixed solution of reducing agent-dispersant-buffer pair.

[0010] (3) Under light-protected conditions at 22-26℃, the above precursor solution is added dropwise to the above reducing agent-dispersant-buffer pair mixed solution at a volume ratio of 1:1 and a rate of 9-11 mL / s while stirring. After titration, the reaction is continued at 22-26℃ for 10-20 min to obtain silver paste solution.

[0011] (4) The above silver paste solution is centrifuged, washed and dried in sequence to obtain the rose-shaped silver powder.

[0012] In a preferred embodiment of the present invention, the molar ratio of aminoacetic acid to silver nitrate is 0.02 to 0.25:1.

[0013] In a preferred embodiment of the present invention, the reducing agent is at least one selected from glucose, ascorbic acid, sodium citrate, and fatty acids.

[0014] More preferably, the reducing agent is ascorbic acid and / or sodium citrate.

[0015] In a preferred embodiment of the present invention, the dispersant is at least one selected from Tween 20, oleic acid, tannin, polyvinylpyrrolidone (PVP), polyethylene glycol-1000 (PEG-1000), and gelatin.

[0016] More preferably, the dispersant is at least one of polyvinylpyrrolidone (PVP), polyethylene glycol-1000 (PEG-1000), and gelatin.

[0017] In a preferred embodiment of the present invention, the buffer pair is tartaric acid-sodium tartrate, citric acid-sodium citrate, or acetic acid-sodium acetate.

[0018] More preferably, the buffer pair is acetic acid-sodium acetate.

[0019] A rose-shaped silver powder is prepared by the above-described method.

[0020] The use of the above-mentioned rose-shaped silver powder in the preparation of surface Raman-enhanced compositions.

[0021] The beneficial effects of this invention are:

[0022] 1. The rose-shaped silver powder obtained by this invention is formed by the self-assembly of sheet-like silver with a thickness of 70nm to 110nm. The petal part of this rose-shaped silver is formed by the deposition of several small sheet-like silver particles. Its surface is rough, its structure is rich, and it has a large number of Raman-enhancing active sites, thus possessing excellent Raman enhancement effect.

[0023] 2. This invention belongs to the liquid-phase chemical reduction method. Gly is added to the precursor solution to control the formation of a continuous and stable sheet-like structure in the system. The addition of dispersant and buffer to the reducing agent solution can promote the self-assembly of flower-like silver powder, effectively prevent the formation of silver powder agglomeration, and maintain the stability of the solution pH in the early stage of the reaction.

[0024] 3. This invention does not introduce seed crystals, and the crystals are self-assembled in one step. Furthermore, no additional adjustment of the pH or temperature of the system is required during the reaction process. The preparation method has the advantages of being simple, efficient, low-cost, and having a large process window, which is conducive to subsequent commercial mass production.

[0025] 4. All chemical reagents involved in this invention are environmentally friendly and have no or low harm to the human body, meeting the requirements of green chemistry advocated today.

[0026] 5. The rose-shaped silver powder obtained by this invention has a stable structure and morphology, good dispersibility, and obvious Raman enhancement effect. Attached Figure Description

[0027] Figure 1 This is a 5000x SEM image of the rose-shaped silver powder prepared in Example 1 of the present invention (one small division on the scale bar in the image represents 1 μm).

[0028] Figure 2 This is a 20,000x SEM image of the rose-shaped silver powder prepared in Example 1 of the present invention (one small division on the scale bar in the image represents 200 nm).

[0029] Figure 3 This is a 5000x SEM image of the comparative silver powder prepared in Comparative Example 1 of this invention (one small division on the scale bar in the image represents 1 μm).

[0030] Figure 4 This is a 5000x SEM image of the comparative silver powder prepared in Comparative Example 2 of this invention (one small division on the scale bar represents 1 μm).

[0031] Figure 5 This is an XRD comparison image of the rose-shaped silver powder prepared in Example 1 of the present invention and a standard silver card.

[0032] Figure 6 The image shows the Raman spectrum of a CV solution using rose-shaped silver powder prepared in Example 1 of this invention as a reinforcing substrate.

[0033] Where a is the Ag base +10 -6 SERS spectrum of CV solution of M, b=10 -4 Ordinary Raman spectrum of CV solution of M, and Raman spectrum of Ag substrate of c. Detailed Implementation

[0034] The technical solution of the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings.

[0035] Example 1

[0036] (1) Preparation of precursor solution: Prepare 20 mL of 0.2 mol / L silver nitrate solution, then add 0.006 g Gly to the silver nitrate solution and stir for 1-2 min until fully dissolved to obtain the precursor solution;

[0037] (2) Preparation of reducing agent-dispersant-buffer pair mixed solution: Prepare 20 mL of 0.15 mol / L ascorbic acid solution; then add 0.025 g gelatin, 0.002 g PVP, 0.004 g acetic acid and 0.03 g sodium acetate to the ascorbic acid solution, heat to 60 °C, stir for 10 min, cool to 25 °C to obtain reducing agent-dispersant-buffer pair mixed solution.

[0038] (3) Under light-protected conditions at 25°C, while sonicating, the above precursor solution was added to the above reducing agent-dispersant-buffer pair mixed solution at a rate of 10 mL / s. After the addition was completed, the reaction was continued at 25°C for 15 min to obtain silver paste solution.

[0039] (4) The above silver paste solution was centrifuged, washed and dried in sequence to obtain the rose-shaped silver powder. The centrifugation parameters were 10000 r / min for 3 min; the washing method was washing with deionized water 3 times and anhydrous ethanol 2 times; the drying conditions were drying in a forced-air drying oven at 70℃ for 6 h.

[0040] Example 2

[0041] (1) Preparation of precursor solution: Prepare 20 mL of 0.2 mol / L silver nitrate solution, then add 0.006 g Gly to the silver nitrate solution and stir for 1-2 min until fully dissolved to obtain the precursor solution;

[0042] (2) Preparation of reducing agent-dispersant-buffer pair mixed solution: Prepare 20 mL of 0.15 mol / L ascorbic acid solution; then add 0.006 g sodium citrate, 0.025 g gelatin, 0.002 g PVP, 0.004 g acetic acid and 0.03 g sodium acetate to the ascorbic acid solution, heat to 60 °C, stir for 10 min, cool to 25 °C to obtain reducing agent-dispersant-buffer pair mixed solution.

[0043] (3) Under light-protected conditions at 25°C, while sonicating, the above precursor solution was added to the above reducing agent-dispersant-buffer pair mixed solution at a rate of 10 mL / s. After the addition was completed, the reaction was continued at 25°C for 15 min to obtain silver paste solution.

[0044] (4) The above silver paste solution was centrifuged, washed and dried in sequence to obtain the rose-shaped silver powder. The centrifugation parameters were 10000 r / min for 3 min; the washing method was washing with deionized water 3 times and anhydrous ethanol 2 times; the drying conditions were drying in a forced-air drying oven at 70℃ for 6 h.

[0045] Example 3

[0046] (1) Preparation of precursor solution: Prepare 20 mL of 0.2 mol / L silver nitrate solution, then add 0.006 g Gly to the silver nitrate solution and stir for 1-2 min until fully dissolved to obtain the precursor solution;

[0047] (2) Preparation of reducing agent-dispersant-buffer pair mixed solution: Prepare 20 mL of 0.15 mol / L ascorbic acid solution; then add 0.025 g gelatin, 0.009 g PEG-1000, 0.004 g acetic acid and 0.03 g sodium acetate to the ascorbic acid solution, heat to 60 °C, stir for 10 min, cool to 25 °C to obtain reducing agent-dispersant-buffer pair mixed solution.

[0048] (3) Under light-protected conditions at 25°C, while sonicating, the above precursor solution was added to the above reducing agent-dispersant-buffer pair mixed solution at a rate of 10 mL / s. After the addition was completed, the reaction was continued at 25°C for 15 min to obtain silver paste solution.

[0049] (4) The above silver paste solution was centrifuged, washed and dried in sequence to obtain the rose-shaped silver powder. The centrifugation parameters were 10000 r / min for 3 min; the washing method was washing with deionized water 3 times and anhydrous ethanol 2 times; the drying conditions were drying in a forced-air drying oven at 70℃ for 6 h.

[0050] Comparative Example 1

[0051] (1) Preparation of precursor solution: Prepare 20 mL of 0.2 mol / L silver nitrate solution to obtain precursor solution;

[0052] (2) Preparation of reducing agent-dispersant-buffer pair mixed solution: Prepare 20 mL of 0.15 mol / L ascorbic acid solution; then add 0.025 g gelatin, 0.002 g PVP, 0.004 g acetic acid and 0.03 g sodium acetate to the ascorbic acid solution, heat to 60 °C, stir for 10 min, cool to 25 °C to obtain reducing agent-dispersant-buffer pair mixed solution.

[0053] (3) Under light-protected conditions at 25°C, while sonicating, the above precursor solution was added to the above reducing agent-dispersant-buffer pair mixed solution at a rate of 10 mL / s. After the addition was completed, the reaction was continued at 25°C for 15 min to obtain silver paste solution.

[0054] (4) The above silver paste solution was centrifuged, washed and dried in sequence to obtain the comparative silver powder. The centrifugation parameters were 10000 r / min for 3 min; the washing method was washing with deionized water 3 times and anhydrous ethanol 2 times; the drying conditions were drying in a forced-air drying oven at 70℃ for 6 h.

[0055] The difference between Comparative Example 1 and Example 1 is that Gly was not added to the precursor solution.

[0056] Comparative Example 2

[0057] (1) Preparation of precursor solution: Prepare 20 mL of 0.2 mol / L silver nitrate solution, then add 0.006 g Gly to the silver nitrate solution and stir for 1-2 min until fully dissolved to obtain the precursor solution;

[0058] (2) Preparation of reducing agent-dispersant-buffer pair mixed solution: Prepare 20 mL of 0.15 mol / L ascorbic acid solution; then add 0.025 g gelatin and 0.002 g PVP to the ascorbic acid solution, heat to 60 °C, stir for 10 min, cool to 25 °C to obtain reducing agent-dispersant-buffer pair mixed solution.

[0059] (3) Under light-protected conditions at 25°C, while sonicating, the above precursor solution was added to the above reducing agent-dispersant-buffer pair mixed solution at a rate of 10 mL / s. After the addition was completed, the reaction was continued at 25°C for 15 min to obtain silver paste solution.

[0060] (4) The above silver paste solution was centrifuged, washed and dried in sequence to obtain the comparative silver powder. The centrifugation parameters were 10000 r / min for 3 min; the washing method was washing with deionized water 3 times and anhydrous ethanol 2 times; the drying conditions were drying in a forced-air drying oven at 70℃ for 6 h.

[0061] The difference between Comparative Example 2 and Example 1 is that no buffer pair was added to the reducing agent solution.

[0062] 0.02 g of rose-shaped silver powder prepared in Example 1 was dispersed in 2 mL of deionized water, dropped onto a cleaned 1 cm × 1 cm silicon wafer, and dried under vacuum at 60 °C for 12 h to obtain a simple substrate. The simple substrate was then immersed in 10... -6 After immersing in crystal violet (CV) solution of M for 6 hours, the sample was removed and Raman enhancement test was performed.

[0063] Depend on Figure 1 and Figure 2 It can be seen that the rose-shaped silver powder prepared in Example 1 of the present invention has a stable flower shape and good particle dispersibility. The rose-shaped silver powder is formed by the self-assembly of sheet silver with a thickness of 70nm to 110nm. The large sheet silver is formed by the deposition of several small sheet silver, so its surface is rough and its structure is rich.

[0064] Depend on Figure 3 and Figure 4It can be seen that Comparative Example 1 did not add Gly, and the silver powder was spherical in shape. Comparative Example 2 did not add buffer pairs, and the morphology of the silver powder was not stable enough. The flake silver failed to self-assemble into good rose-shaped silver powder.

[0065] Depend on Figure 5 It can be seen that the rose-shaped silver powder prepared in Example 1 of the present invention has excellent crystallinity and no other crystallization impurities are generated, indicating that the rose-shaped silver powder prepared in Example 1 of the present invention has high purity.

[0066] Depend on Figure 6 It can be seen that the characteristic peaks of a are significantly stronger than those of b, that is, the rose-shaped silver powder prepared by Example 1 of the present invention has a significant Raman enhancement effect.

[0067] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing rose-shaped silver powder with Raman enhancement effect, characterized in that: Includes the following steps: (1) Prepare a silver nitrate solution, then add glycine to the silver nitrate solution and dissolve it completely to obtain a precursor solution. The molar ratio of glycine to silver nitrate is 0.02–0.25:1; (2) Prepare a reducing agent solution; then mix the dispersant, buffer pair and reducing agent in deionized water and heat to 58-62°C and stir evenly, then cool to 22-26°C to obtain a reducing agent-dispersant-buffer pair mixed solution; the reducing agent is at least one of glucose, ascorbic acid, sodium citrate and fatty acid, the dispersant is at least one of Tween 20, oleic acid, tannin, polyvinylpyrrolidone, polyethylene glycol-1000 and gelatin, and the buffer pair is tartaric acid-sodium tartrate, citric acid-sodium citrate or acetic acid-sodium acetate; (3) Under light-protected conditions at 22-26℃, the above precursor solution is added dropwise to the above reducing agent-dispersant-buffer pair mixed solution at a volume ratio of 1:1 and a rate of 9-11 mL / s while stirring. After titration, the reaction is continued at 22-26℃ for 10-20 min to obtain silver paste solution. (4) The above silver paste solution is centrifuged, washed and dried in sequence to obtain the rose-shaped silver powder.

2. The preparation method according to claim 1, characterized in that: The reducing agent is ascorbic acid and / or sodium citrate.

3. The preparation method according to claim 1, characterized in that: The dispersant is at least one of polyvinylpyrrolidone, polyethylene glycol-1000, and gelatin.

4. The preparation method according to claim 1, characterized in that: The buffer pair is acetic acid-sodium acetate.

5. A rose-shaped silver powder, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 4.

6. Use of the rose-shaped silver powder of claim 5 in the preparation of surface Raman-enhanced compositions.

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