CN-122007433-A - Method for manufacturing silver-coated copper nanowires with core-shell structure using chemical reduction method

Abstract

The present invention relates to silver-coated copper nanowires having a core-shell structure using chemical reduction and a method of preparing the same. More particularly, the present invention relates to a method of preparing silver-coated copper nanowires, which includes chemically producing copper nanowires, and coating copper surfaces with silver using a silver ammine complex solution and a reducing agent, thereby preventing oxidation of the copper nanowires by chemical reduction, and silver-coated copper nanowires having a core-shell structure produced by the method. In addition, since copper nanowires can be produced by reusing the solution, production costs can be reduced. The method of preparing silver-coated copper nanowires having a core-shell structure according to the present invention can prevent deterioration of conductivity by preventing oxidation even in air or at high temperature, and thus is useful for production of electromagnetic shielding paste or high-conductivity paste requiring high conductivity.

Inventors

• Pu Hanwu
• JIN ZAIHE
• JIN JUNBIAO
• Yin Guojin

Assignees

• 柏业公司

Dates

Publication Date

20260512

Application Date

20170530

Priority Date

20160603

Claims (11)

1. 1. A method of preparing silver-coated copper nanowires having a core-shell structure, the method comprising: (a) Stirring an aqueous solution containing (1) a base, (2) a copper compound, and (3) a capping agent in water; (b) Producing copper nanowires by adding a reducing agent to the aqueous solution to reduce copper ions; (c) Washing and drying the copper nanowires produced; (d) Removing the oxide film from the copper nanowires produced in step (c) in a copper nanowire solution; (e) Adding a reducing agent to the solution of step (d), adjusting the pH to 8 to 10 and then forming a silver coating layer while adding the silver nitrate-ammonia complex solution dropwise, and (F) Washing and drying the silver-coated copper nanowires prepared in step (e).
2. 2. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, further comprising (c ') resynthesizing copper nanowires by adding a copper precursor and a reducing agent to a solution separated from the copper nanowires after step (c), and synthesizing copper nanowires by repeating step (c') two or more times.
3. 3. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein a mixed solution of ammonia water and ammonium sulfate is used as a solution for removing the oxide film in the step (d), and The concentration of the mixed solution of ammonia water and ammonium sulfate in step (d) is 0.001 to 0.3M.
4. 4. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein the step (b) is performed at a temperature of 0 to 100 ℃, and the step (d) is performed for 1 to 60 minutes.
5. 5. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein, in step (e), the reducing agent is added to the copper nanowire solution from which the oxide film is removed in step (d), the pH is adjusted, and the silver nitrate-ammonia complex solution is injected at 0.5 to 500 ml/min while stirring at 50 to 1600 rpm, Wherein the silver nitrate-ammonia complex solution is prepared by mixing a silver nitrate solution with aqueous ammonia, Wherein the concentration of silver nitrate in the silver nitrate-ammonia complex solution is 0.001 to 1M, and Wherein the concentration of the ammonia water in the silver nitrate-ammonia complex solution is 0.01-0.3M.
6. 6. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein the reducing agent in step (e) is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tridecanedioic acid, dodecanoic acid, hexadecanedioic acid, maleic acid, fumaric acid, gluconic acid, callic acid, muconic acid, citraconic acid, mesaconic acid, aspartic acid, glutamic acid, diaminopimelic acid, tartronic acid, arabinodiac acid, glucaric acid, oxalic acid, oxaloacetic acid, acetonedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, diphthalic acid, tartaric acid, potassium sodium tartrate, ascorbic acid, hydroquinone and glucose, and the concentration of the reducing agent is 0.001M to 3M.
7. 7. The method for preparing silver-coated copper nanowires having a core-shell structure of claim 1, wherein the base (1) in step (a) is NaOH, KOH or Ca (OH) 2 , The concentration of the base (1) is 2.5 to 25M.
8. 8. The method for producing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein the copper compound (2) in step (a) is copper hydroxide, copper nitrate, copper sulfate, copper sulfite, copper acetate, copper chloride, copper bromide, copper iodide, copper phosphate or copper carbonate, The concentration of the copper compound in step (a) is 0.004 to 0.5M based on copper ions.
9. 9. The method for preparing silver-coated copper nanowires having a core-shell structure of claim 1, wherein the (3) capping agent is piperazine (C 4 H 10 N 2 ) or hexamethylenediamine (C 6 H 16 N 2 ), The concentration of the capping agent is 0.008 to 2.0M.
10. 10. The method for preparing silver-coated copper nanowires having a core-shell structure according to claim 1, wherein the reducing agent in step (b) is hydrazine, ascorbic acid, L (+) -ascorbic acid, isoascorbic acid, an ascorbic acid derivative, oxalic acid, formic acid, phosphite, phosphoric acid, sulfite or sodium borohydride, The concentration of the reducing agent in step (b) is from 0.01 to 1.0M, and The reducing agent in step (b) is added at a rate of 0.1 to 500 ml/min.
11. 11. The method of preparing a silver-coated copper nanowire having a core-shell structure according to any one of claims 1 to 10, wherein the silver-coated copper nanowire is prepared by a batch reaction, a plug flow reaction, or a continuous stirred tank type reaction process.

Description

Method for manufacturing silver-coated copper nanowires with core-shell structure using chemical reduction method The application is a divisional application of China patent application (application date: 2017, 5, 30, title of the application: method for manufacturing silver-coated copper nanowires with core-shell structure by using chemical reduction method) with application number 201780041973.1. Technical Field The present invention relates to a method of preparing silver-coated copper nanowires having a core-shell structure using chemical reduction, and more particularly, to a method of preparing silver-coated copper nanowires, which includes chemically producing copper nanowires, and coating copper surfaces with silver using a silver ammine complex solution and a reducing agent, thereby preventing oxidation of the copper nanowires by chemical reduction. Background Nanowires are nanomaterial having a diameter of several nanometers and a length of several hundred nanometers to several hundred micrometers, and such materials have attracted much attention as core materials for producing next-generation nano-devices due to ease of manual operation. Recently, metal nanowires such as copper, silver, and nickel nanowires have been usefully used as substitutes for Indium Tin Oxide (ITO), conductive polymers, carbon nanotubes, graphite, and the like due to characteristics such as conductivity and transparency. Among them, copper nanowires are emerging as substitutes for Indium Tin Oxide (ITO) that have been mainly used for displays due to advantages such as high conductivity, flexibility, transparency, and low cost. In particular, because copper nanowires are transparent conductors, they can be used in a wide variety of applications, including low-emissivity windows, touch sensitive panels, solar cells, and electromagnetic shielding materials. Conventionally, copper nanowires have been produced by a variety of methods, such as electrochemical reactions, chemical vapor deposition, hard template assisted methods, and colloid and hydrothermal processes. However, the conventional manufacturing method has problems such as high equipment investment cost, difficulty in controlling the size of the nanowire, and low productivity. Recently, methods for manufacturing copper nanowires by chemical synthesis have been known. Korean patent No. 10-73808 discloses a method for preparing copper nanowires, which includes mixing an amine ligand, a reducing agent, a surface active and a nonpolar organic solvent with an aqueous solution of CuCl 2, transferring the reaction solution into a high-pressure reactor and performing a reaction at 80 to 200 ℃ for 24 hours. The copper nanowires produced by this method have a length of 10 to 50 μm and a diameter of 200 to 1,000 nm. However, this production method is performed using a high-pressure reactor, which may cause problems of increased production costs and unsuitable mass production. Korean patent No. 1334601 discloses a method for preparing copper nanowires by a polyol process using Ethylene Glycol (EG) and polyvinylpyrrolidone (PVP). However, this production method causes environmental problems due to the use of a toxic solvent as compared with the case where an aqueous solution is used as a solvent, and has a problem of deteriorated economic efficiency due to increased production costs. International patent publication No. 2011-071885 discloses a method of manufacturing a copper nanowire having a length of 1 to 500 μm and a diameter of about 20 to 300 nm by mixing a copper ion precursor, a reducing agent, a capping agent, and a pH adjuster, and then reacting at a predetermined temperature to obtain a copper nanowire including a copper rod attached to spherical copper nanoparticles. However, this method still has drawbacks such as low productivity and low quality uniformity of the copper nanowires produced. On the other hand, when copper nanowires are exposed to air for a long period of time, oxidation occurs to form copper oxide. This oxidation phenomenon proceeds more rapidly with increasing temperature. Such copper oxide is significantly less conductive than pure copper. In order to prevent the generation of such copper oxide, international patent publication No. 2011-071885 and korean patent publication No. 1334601 disclose the production of copper nanowires and the surface treatment of the copper nanowires with metals such as nickel, gold, tin, zinc, silver, platinum, titanium, aluminum, tungsten, cobalt, or the like. However, there remains a need to improve the overall process efficiency and quality uniformity of copper nanowires. Accordingly, as a result of a great deal of effort to solve the above problems, the inventors of the present invention developed a method for coating the surface of a chemically synthesized copper nanowire with silver to prevent oxidation by chemical reduction using a silver ammine complex solution and a reducing agent, and found that the method enable