An efficient preparation method and product of silver nanowires

Abstract

An efficient preparation method of silver nanowires. First, a silver ion solution and a stabilizer are fully mixed in the required proportions to obtain solution A. Then, a reducing agent is added to solution A in the required proportion, and after a full reaction, solution B is obtained. The reducing agent is a mixed solution of nano copper and water. Then, solution B is centrifuged and washed successively to obtain silver nanowires. In this method, nano copper is used as a reducing agent to undergo a displacement reduction reaction with the silver ion solution to achieve anisotropic growth and finally form silver nanowires. Not only are the preparation steps simple and the synthesis fast, but the whole reaction is carried out under low-temperature ultrasonic conditions, avoiding the harsh conditions of high temperature and high pressure, and having extremely low requirements for reaction conditions. This method uses water as a solvent, avoiding the use of toxic organic solvents such as ethylene glycol, meeting the requirements of green development. Finally, the generated silver nanowires have fewer impurities. The diameter of the silver nanowires is 20-100 nm, the length is 30-120 μm, and the aspect ratio is as high as 1000.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and specifically relates to a high-efficiency preparation method and product of silver nanowires. Background Art

[0002] With the development of science and technology, flexible transparent conductive electrodes (FTCE) are favored as important components of optoelectronic devices such as touch screen films, liquid crystal displays, and solar cells. As a traditional FTCE material, tin oxide (ITO) has excellent transmittance and resistivity, but its application prospects are limited due to its high energy consumption, scarce resources, high cost, and high brittleness. With the development of FTCE, ITO has been gradually replaced by flexible conductive materials such as conductive polymers, carbon nanotubes, graphene, and metal nanowires. In particular, silver nanowires have very excellent electrical, optical, and thermal properties, and their performance can be optimized and tailored by controlling the morphology of silver nanowires, so that they have potential application value in optoelectronic devices, flexible conductors, touch screens, organic photovoltaic devices, and other fields. It is considered to be the most promising material to replace ITO.

[0003] At present, there are three methods for synthesizing silver nanowires: template method, hydrothermal method, and polyol reduction method. The template used in the template method needs to be removed by corrosion reaction, which will damage the synthesized silver nanowires to a certain extent, and the yield is low. The hydrothermal method often requires the use of a high-pressure reactor, and the preparation conditions are harsh and it is difficult to achieve mass production. Although the polyol reduction method has the advantages of easy availability of raw materials, controllable morphology, and convenient post-processing, it requires high temperature, long reaction time, and low purity, and often requires a series of complex purification measures. Therefore, it is particularly important to develop a green and safe method for preparing silver nanowires with simple preparation steps, low requirements for reaction conditions. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method and product for preparing silver nanowires which has simple preparation steps, low requirements on reaction conditions and is green and safe.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A method for efficiently preparing silver nanowires, the method comprising the following steps in sequence:

[0007] S1, fully mixing the silver ion solution and the stabilizer in a desired ratio to obtain solution A;

[0008] S2. Adding solution A to a reducing agent in a desired proportion to obtain solution B at 0-40° C., and then centrifuging and washing solution B in sequence to obtain silver nanowires, wherein the reducing agent is a mixture of nano copper and water.

[0009] The volume ratio of the silver ion solution, the stabilizer, and the reducing agent is 1-10:1-10:1-16.

[0010] The solute in the stabilizer is at least one of sodium citrate, halide, hexadecyltrimethylammonium bromide, and polyvinylpyrrolidone. The solvent in the stabilizer is water, and the concentration of the solute is 1-100 mg / mL.

[0011] The halide is KCl, KBr, NaCl, FeCl3, or CuCl2.

[0012] The molecular weight of the polyvinylpyrrolidone is at least one of 10,000, 40,000, and 800,000.

[0013] In step S2, after adding the reducing agent to solution A in the required proportion, ultrasonic treatment is performed at 0-40 °C to obtain solution B, and the duration of the ultrasonic treatment is 5-30 min.

[0014] After the ultrasonic treatment in step S2, the concentration of silver nanowires in solution B is 2.157-10.787 mg / mL.

[0015] The concentration of nano copper in the reducing agent is 0.49-1.64 mg / mL, and the nano copper is copper nanoparticle clusters, copper nanosheets, or copper nanospheres.

[0016] The silver ion solution is an aqueous silver nitrate solution, a silver halide solution, or a silver ammonia solution, and the concentration of silver ions in the silver ion solution is 1.6987-84.935 mg / mL.

[0017] A silver nanowire, which is prepared by using the above method.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] In an efficient preparation method of silver nanowires according to the present invention, first, a silver ion solution and a stabilizer are fully mixed in a required ratio to obtain solution A. Then, a reducing agent is added to solution A in a required ratio, and after a full reaction, solution B is obtained. The reducing agent is a mixed solution of nano copper and water. Then, solution B is centrifuged and washed in sequence to obtain silver nanowires. This preparation method uses nano copper as a reducing agent to undergo a displacement reduction reaction with the silver ion solution, achieving anisotropic growth and finally forming silver nanowires. Not only is the preparation step simple, and the synthesis can be completed in 5 - 30 minutes, with fast and efficient synthesis, but also the displacement reduction reaction is carried out under low-temperature ultrasonic conditions throughout, avoiding the harsh conditions of high temperature and high pressure, and having extremely low requirements for reaction conditions. This method uses water as a solvent, avoiding the use of toxic organic solvents such as ethylene glycol, and no harmful substances are generated during the displacement reduction reaction process, meeting the requirements of green development. Finally, the obtained silver nanowires have fewer impurities, with a diameter of 20 - 100 nm and a length of 30 - 120 μm, and an aspect ratio as high as 1000, having excellent optical and electrical conductivity. Therefore, the preparation method of the present invention has simple steps, low requirements for reaction conditions, is green and safe, the obtained silver nanowires have few impurities and an aspect ratio as high as 1000, and have excellent optical and electrical conductivity. Description of the Drawings

[0020] Figure 1 SEM image of the product obtained in Example 1.

[0021] Figure 2 SEM image of the product obtained in Example 2.

[0022] Figure 3 SEM image of the product obtained in Example 3.

[0023] Figure 4 SEM image of the product obtained in Example 4.

[0024] Figure 5 SEM image of the product obtained in Example 5.

[0025] Figure 6 XRD pattern of the product obtained in Example 1. Detailed Embodiments

[0026] The present invention will be further described below in conjunction with the drawings of the specification and the detailed embodiments.

[0027] An efficient preparation method of silver nanowires, the preparation method successively includes the following steps:

[0028] S1. A silver ion solution and a stabilizer are fully mixed in a required ratio to obtain solution A;

[0029] S2. Adding solution A to a reducing agent in a desired proportion to obtain solution B at 0-40° C., and then centrifuging and washing solution B in sequence to obtain silver nanowires, wherein the reducing agent is a mixture of nano copper and water.

[0030] The volume ratio of the silver ion solution, the stabilizer and the reducing agent is 1-10:1-10:1-16.

[0031] The solute in the stabilizer is at least one of sodium citrate, halides, hexamethylammonium bromide and polyvinyl pyrrolidone, the solvent in the stabilizer is water, and the concentration of the solute is 1-100 mg / mL.

[0032] The halide is KCl, KBr, NaCl, FeCl3 or CuCl2.

[0033] The molecular weight of the polyvinyl pyrrolidone is at least one of 10,000, 40,000, and 800,000.

[0034] In step S2, after adding a reducing agent to solution A in a desired proportion, ultrasonic treatment is performed at 0-40° C. to obtain solution B, wherein the duration of the ultrasonic treatment is 5-30 min.

[0035] In step S2, after the ultrasound treatment, the concentration of silver nanowires in solution B is 2.157-10.787 mg / mL.

[0036] The concentration of nano copper in the reducing agent is 0.49-1.64 mg / mL, and the nano copper is a copper nanoparticle cluster, a copper nanosheet or a copper nanosphere.

[0037] The silver ion solution is a silver nitrate aqueous solution, a silver halide solution or a silver ammonia solution, and the concentration of silver ions in the silver ion solution is 1.6987-84.935 mg / mL.

[0038] A silver nanowire is prepared by the method.

[0039] Embodiment 1:

[0040] An efficient preparation method of silver nanowires is specifically carried out according to the following steps:

[0041] S1. Fully mix the silver ion solution and the stabilizer in a desired ratio to obtain solution A, wherein the volume ratio of the silver ion solution to the stabilizer is 1:1, the silver ion solution is a mixture of silver nitrate and water, the silver ion concentration in the silver ion solution is 33.974 mg / mL, the stabilizer is a mixture of polyvinyl pyrrolidone and water, the polyvinyl pyrrolidone concentration in the stabilizer is 10 mg / mL, and the molecular weight of the polyvinyl pyrrolidone is 40000;

[0042] S2. Add a reducing agent to solution A in the required proportion and ultrasonicate for 15 min at 0 °C to obtain solution B. The concentration of silver nanowires in solution B after ultrasonication is 2.358 mg / mL. Subsequently, solution B is centrifuged and washed in sequence to obtain silver nanowires. The finally obtained silver nanowires have an average diameter of 82 nm and an average length of 117 μm. Among them, the volume ratio of the silver ion solution to the reducing agent is 1:13. The reducing agent is a mixed solution of nano-copper and water, and the concentration of nano-copper in the reducing agent is 0.492 mg / mL. The nano-copper is copper nanoparticle clusters.

[0043] Example 2:

[0044] The steps are the same as those in Example 1, except that:

[0045] In step S1, the stabilizer is a mixed solution of hexadecyltrimethylammonium bromide and water, and the concentration of hexadecyltrimethylammonium bromide in the stabilizer is 10 mg / mL;

[0046] In step S2, the volume ratio of the silver ion solution to the reducing agent is 1:8. The concentration of nano-copper in the reducing agent is 0.8 mg / mL. The concentration of silver nanowires in solution B after ultrasonication is 2.440 mg / mL. The finally obtained silver nanowires have an average diameter of 78 nm and an average length of 113 μm.

[0047] Example 3:

[0048] The steps are the same as those in Example 1, except that:

[0049] In step S2, after adding the reducing agent to solution A in the required proportion, let it stand at room temperature for 15 min to obtain solution B. The volume ratio of the silver ion solution to the reducing agent is 1:8. The concentration of nano-copper in the reducing agent is 0.8 mg / mL. The concentration of silver nanowires in solution B after standing at room temperature is 2.285 mg / mL. The finally obtained silver nanowires have an average diameter of 79 nm and an average length of 114 μm.

[0050] Example 4:

[0051] The steps are the same as those in Example 1, except that:

[0052] In step S1, the stabilizer is a mixed solution of polyvinylpyrrolidone, NaCl and water. The concentration of the solvent in the stabilizer is 10 mg / mL, and the mass ratio of polyvinylpyrrolidone to NaCl is 1:5;

[0053] In step S2, the volume ratio of the silver ion solution to the reducing agent is 1:8. The concentration of nano copper in the reducing agent is 0.8 mg / mL. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 2.306 mg / mL. The finally obtained silver nanowires have an average diameter of 83 nm and an average length of 107 μm.

[0054] Example 5:

[0055] The steps are the same as those in Example 1, except that:

[0056] The amounts of substance of the silver ion solution, the stabilizer, and the reducing agent are scaled up by 20 times in proportion with reference to Example 1. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 2.382 mg / mL. The finally obtained silver nanowires have an average diameter of 84 nm and an average length of 110 μm.

[0057] Example 6:

[0058] The steps are the same as those in Example 1, except that:

[0059] In step S1, the volume ratio of the silver ion solution to the stabilizer is 1:10, and the concentration of silver ions in the silver ion solution is 58.524 mg / mL;

[0060] In step S2, the volume ratio of the silver ion solution to the reducing agent is 1:16. The concentration of nano copper in the reducing agent is 0.8 mg / mL. The nano copper is copper nanosheets. The temperature of the ultrasonic treatment is room temperature and the duration is 25 min. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 4.793 mg / mL. The finally obtained silver nanowires have an average diameter of 72 nm and an average length of 94 μm.

[0061] Example 7:

[0062] The steps are the same as those in Example 1, except that:

[0063] In step S1, the volume ratio of the silver ion solution to the stabilizer is 1:2, and the concentration of silver ions in the silver ion solution is 84.935 mg / mL. The stabilizer is a mixed solution of sodium citrate and water, and the concentration of sodium citrate in the stabilizer is 45 mg / mL;

[0064] In step S2, the volume ratio of the silver ion solution to the reducing agent is 1:7. The concentration of nano copper in the reducing agent is 1.64 mg / mL. The nano copper is copper nanosheets. The temperature of the ultrasonic treatment is 30 °C and the duration is 25 min. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 10.087 mg / mL. The finally obtained silver nanowires have an average diameter of 20 nm and an average length of 30 μm.

[0065] Example 8:

[0066] The steps are the same as those in Example 1, except that:

[0067] In step S1, the volume ratio of the silver ion solution to the stabilizer is 3:1, the silver ion concentration in the silver ion solution is 62.374 mg / mL, the stabilizer is a mixed solution of polyvinylpyrrolidone, NaCl and water, the solute concentration in the stabilizer is 100 mg / mL, the mass ratio of polyvinylpyrrolidone to NaCl is 1:5, and the molecular weight of polyvinylpyrrolidone is 800,000;

[0068] In step S2, the volume ratio of the silver ion solution to the reducing agent is 3:10, the concentration of copper nanoparticles in the reducing agent is 0.61 mg / mL, the copper nanoparticles are copper nanosheets, the temperature of the ultrasonic treatment is 10 °C and the duration is 20 min. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 5.157 mg / mL, and the finally obtained silver nanowires have an average diameter of 59 nm and an average length of 62 μm.

[0069] Example 9:

[0070] The steps are the same as those in Example 1, except that:

[0071] In step S1, the volume ratio of the silver ion solution to the stabilizer is 10:1, the silver ion concentration in the silver ion solution is 21.526 mg / mL, the stabilizer is a mixed solution of polyvinylpyrrolidone, KCl and water, the solute concentration in the stabilizer is 45 mg / mL, the mass ratio of polyvinylpyrrolidone to KCl is 4:1, and the molecular weight of polyvinylpyrrolidone is 10,000;

[0072] In step S2, the volume ratio of the silver ion solution to the reducing agent is 10:1, the concentration of copper nanoparticles in the reducing agent is 1.25 mg / mL, the copper nanoparticles are copper nanosheets, the temperature of the ultrasonic treatment is 40 °C and the duration is 5 min. After the ultrasonic treatment, the concentration of silver nanowires in solution B is 2.369 mg / mL, and the finally obtained silver nanowires have an average diameter of 28 nm and an average length of 57 μm.

[0073] Example 10:

[0074] The steps are the same as those in Example 1, except that:

[0075] In step S1, the volume ratio of the silver ion solution to the stabilizer is 4:1, the silver ion solution is a mixed solution of silver nitrate and water, the silver ion concentration in the silver ion solution is 58.524 mg / mL, the stabilizer is a mixed solution of KBr, FeCl3, CuCl2 and water, the solute concentration in the stabilizer is 20 mg / mL, and the mass ratio of KBr, FeCl3, CuCl2 is 1:1:1;

[0076] In step S2, a reducing agent is added to solution A in a required ratio and then left standing at room temperature for 10 min to obtain solution B. The volume ratio of the silver ion solution to the reducing agent is 4:2. The concentration of copper nanoparticles in the reducing agent is 0.76 mg / mL. The copper nanoparticles are copper nanospheres. After standing at room temperature, the concentration of silver nanowires in solution B is 6.412 mg / mL. The finally obtained silver nanowires have an average diameter of 100 nm and an average length of 120 μm.

[0077] Performance analysis

[0078] 1. The scanning electron microscope photos of the products prepared in Examples 1-5 are respectively as Figures 1-5 shown. It can be seen from the figures that the silver nanowires prepared by the method of the present invention have fewer impurities, are evenly dispersed and have uniform sizes;

[0079] 2. The XRD analysis of the product prepared in Example 1 is carried out, and the analysis results are as Figure 6 shown. It can be seen from the figures that these diffraction peaks are in good agreement with the (111), (200), (220) and (311) planes of face-centered cubic Ag, and no other diffraction peaks are observed, which proves that the synthesized AgNWs have good crystallinity and high purity. Among them, the diffraction peak of the (111) plane is the strongest, indicating that Ag atoms are preferentially deposited on the (111) plane, causing the silver atoms to grow along the

[110] direction.

Claims

1. An efficient method for preparing silver nanowires, characterized in that: The preparation method comprises the following steps in sequence: S1, fully mixing the silver ion solution and the stabilizer in a desired ratio to obtain solution A; The silver ion solution is a silver nitrate aqueous solution, and the concentration of silver ions in the silver ion solution is 1.6987-84.935 mg / mL; S2, adding solution A to a reducing agent in a desired proportion to obtain solution B at 0-40° C., and then centrifuging and washing solution B in sequence to obtain silver nanowires, wherein the reducing agent is a mixture of nanocopper and water; the concentration of nanocopper in the reducing agent is 0.49-1.64 mg / mL, and the nanocopper is a cluster of copper nanoparticles; The volume ratio of the silver ion solution, the stabilizer and the reducing agent is 1-10:1-10:1-16.

2. The method for efficiently preparing silver nanowires according to claim 1, characterized in that: The solute in the stabilizer is at least one of sodium citrate, halides, hexamethylammonium bromide and polyvinyl pyrrolidone, the solvent in the stabilizer is water, and the concentration of the solute is 1-100 mg / mL.

3. The method for efficiently preparing silver nanowires according to claim 2, characterized in that: The halide is KCl, KBr, NaCl, FeCl3 or CuCl2.

4. The method for efficiently preparing silver nanowires according to claim 2, characterized in that: The molecular weight of the polyvinyl pyrrolidone is at least one of 10,000, 40,000, and 800,000.

5. The method for efficiently preparing silver nanowires according to claim 1, characterized in that: In step S2, after adding a reducing agent to solution A in a desired proportion, ultrasonic treatment is performed at 0-40° C. to obtain solution B, wherein the duration of the ultrasonic treatment is 5-30 min.

6. The method for efficiently preparing silver nanowires according to claim 5, characterized in that: In step S2, after the ultrasound treatment, the concentration of silver nanowires in solution B is 2.157-10.787 mg / mL.

7. A silver nanowire, characterized in that: The silver nanowires are prepared by the method according to any one of claims 1 to 6.

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