Preparation method of ultra-long copper nanowire

Abstract

The invention discloses a preparation method of a super-long copper nanowire, which comprises the following steps: 1, dissolving copper chloride, sodium chloride and an organic surfactant in deionized water to obtain a mixed solution; 2, adding sodium hydroxide into the mixed solution to obtain a copper hydroxide precursor suspension; 3, adding a reducing agent into the turbid liquid, and then carrying out hydrothermal reduction reaction; and 4, washing and drying the product after the hydrothermal reduction reaction to obtain the ultra-long copper nanowire. Copper chloride is adopted as a copper source, a sodium hydroxide aqueous solution is added, hydroxyl reacts with copper ions to form a copper hydroxide precursor, then the copper hydroxide precursor is reduced into elemental copper through a hydrothermal reduction reaction under the action of a reducing agent, and therefore the ultra-long copper nanowire is formed. The method ensures that the obtained copper nanowire is easy to clean and purify with deionized water, reduces the preparation cost, reduces the emission of polluting products, and can be used as a low-cost metal conductive filler for preparing electronic paste.

Description

Technical Field

[0001] The invention belongs to the technical field of metal nanomaterial preparation, and in particular relates to a method for preparing an ultra-long copper nanowire. Background Art

[0002] Copper has the advantages of excellent conductivity, low cost, and abundant reserves. It is widely used in aerospace, energy and chemical, and electronic information fields. It is an extremely common metal material in modern industry and life. With the rise of flexible printed electronics technology, nanoscale copper materials have become a hot topic of research, and nano-copper is expected to become a metal nano-conductive filler used on a large scale in the future. Nano-copper mainly includes zero-dimensional copper nanoparticles, one-dimensional copper nanowires, and two-dimensional copper nanosheets. At present, they have all been successfully synthesized and applied to flexible films or electronic circuits. Among them, the flexible electronic devices prepared with copper nanowire conductive fillers can still be well overlapped when stretched or folded, so that the electronic devices have better conductivity. Therefore, low-cost, ultra-long copper nanowires have very good application prospects in the flexible electronics industry.

[0003] At present, the preparation of copper nanowires mainly adopts the template method and liquid phase reduction method. In view of the template method, such as the invention patents disclosed in application numbers 201910401737.7 and 201811166559.6, the process of preparing copper nanowires requires the addition of cumbersome steps of template elimination, and the liquid phase reduction method with simple steps has gradually become the main development direction of copper nanowire preparation. However, most of the existing liquid phase reduction methods for preparing copper nanowires have the problem of excessive use of organic reagents, which makes cleaning and purification more difficult. For example, the copper nanowires prepared by the liquid phase reduction method disclosed in the invention patents with application numbers 202210281254.X, 202210414375.7, 201611155853.8, and 202211034162.8 all use oleylamine, oleic acid, hexadecylamine or octadecylamine as organic capping agents, resulting in the need for a large amount of organic solvents such as n-hexane and anhydrous ethanol to clean the product. The invention patent with application number 202210253227.1 discloses a method for synthesizing ultra-pure copper nanowires. Although this method does not require the addition of long-chain organic alkylamines, it requires the simultaneous addition of multiple organic compounds such as organic protective agents, organic chlorine-containing halides and polyols. In addition, the amount of polyvinyl pyrrolidone added as an organic protective agent is large, which makes the copper nanowires not only difficult to clean, but also has a high preparation cost.

[0004] In recent years, researchers have been committed to developing processes that do not add or add less organic reagents for the preparation of copper nanowires. For example, the use of hydrazine hydrate to reduce copper ions in a high concentration of sodium hydroxide aqueous solution to prepare copper nanowires has been successful. Although no organic reagents are added, the high concentration (10-15M) of sodium hydroxide solution makes the preparation process extremely dangerous, and copper nanowires are prone to surface oxidation in alkaline solutions (Langmuir, 2005, 21, 3746-3748; J. Am. Chem. Soc., 2017, 139, 277-284). By adding a small amount of hexadecyltrimethylammonium chloride and using green ascorbic acid as a reducing agent, copper nanowires can be prepared by a hydrothermal method, but cuprous chloride as a copper source is difficult to dissolve in water, the reaction takes a long time, and it is difficult to obtain pure copper nanowires (Materials Chemistry and Physics, 2010, 120, 1-5). In general, the preparation methods of copper nanowires tend to be free of the use of long-chain alkylamines and can be prepared in large quantities under mild conditions. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing ultra-long copper nanowires in view of the deficiencies of the above-mentioned prior art. In the method, a copper hydroxide precursor is formed by the reaction of hydroxide and copper ions in an aqueous phase system, and then the precursor is reduced to copper nanowires by a hydrothermal reduction reaction under the action of a reducing agent. The preparation process is simple, no highly polluting chemical reagents are used, and it is easy to industrialize production. Only a small amount of organic surfactant soluble in water is added as an organic reagent, and all raw materials are soluble in water, so that the cleaning and purification of the product copper nanowires are extremely simple and green and environmentally friendly.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing ultra-long copper nanowires, characterized in that the method includes a liquid phase coprecipitation reaction and a hydrothermal reduction reaction, and specifically includes the following steps:

[0007] Step 1, dissolving copper chloride, sodium chloride and an organic surfactant in deionized water, stirring evenly to obtain a mixed solution; the volume of the mixed solution is 35mL-64mL, the mass concentration of copper chloride in the mixed solution is 1g / L-10g / L, the mass concentration of sodium chloride is 0.1g / L-1g / L, and the mass concentration of the organic surfactant is 1g / L-10g / L;

[0008] Step 2: Add 5 mL to 10 mL of sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, stir and react to obtain a copper hydroxide precursor suspension;

[0009] Step 3, adding 1 mL to 5 mL of reducing agent aqueous solution to the copper hydroxide precursor suspension obtained in step 2, then stirring evenly to form a reaction solution, and performing a hydrothermal reduction reaction; the temperature of the hydrothermal reduction reaction is 120° C. to 180° C., and the time is 5 h to 10 h;

[0010] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried to obtain ultra-long copper nanowires.

[0011] The present invention adopts cupric chloride which is easily soluble in water as a copper source, and adds an appropriate amount of sodium hydroxide aqueous solution to make hydroxide react with copper ions to form a copper hydroxide precursor, and then under the action of a reducing agent, a hydrothermal reduction reaction is performed to completely reduce the copper hydroxide precursor to elemental copper growing along a one-dimensional direction, thereby forming pure ultra-long copper nanowires.

[0012] In the present invention, a small amount of organic surfactant is used to be adsorbed on the surface of the copper hydroxide precursor and the copper nanowires, so that the final product copper nanowires are made longer, thinner and more dispersed, and agglomeration during the growth process is prevented. By using sodium chloride, the chloride ions therein can etch defects such as protrusions and burrs of the copper nanowires during the growth process. The two work together to ensure the formation of ultra-long and ultra-thin copper nanowires.

[0013] The present invention controls the mass concentration of the organic surfactant and the sodium chloride to ensure the maximum gain in the formation of the copper nanowires and ensures that the obtained copper nanowires are easy to be cleaned and purified with deionized water, thereby reducing costs and being beneficial to environmental protection.

[0014] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the organic surfactant in step 1 is one or more of dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride and eicosyltrimethylammonium chloride. The organic surfactants used in the present invention are all soluble in water and are added in a relatively low amount, thereby ensuring that the copper nanowires can be prepared and quickly cleaned in an aqueous phase.

[0015] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the mass concentration of the sodium hydroxide aqueous solution in step 2 is 50g / L, the volume of the sodium hydroxide aqueous solution added is 5mL, and the stirring reaction time is 10min. In the present invention, the amount of sodium hydroxide added is controlled so that it can fully react with copper ions to form a copper hydroxide precursor. Excessive sodium hydroxide will not only increase the danger of the reaction solution, but also may cause the copper nanowires obtained after the reaction to be easily oxidized.

[0016] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the mass concentration of the reducing agent aqueous solution in step 3 is 10g / L, and the amount of the reducing agent aqueous solution added is 2mL. The present invention controls the amount of reducing agent added so that the product can just form a nanowire morphology. Too much or too little reducing agent addition will lead to the formation of amorphous nanoparticles.

[0017] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the reducing agent in step 3 is one or more of ascorbic acid, sodium ascorbate, glucose, cysteine, arginine, threonine, proline, and serine. The reducing agents used in the present invention are all green and environmentally friendly reagents, which will not produce toxic and harmful waste liquids and waste gases, and the reduction process is relatively mild. The reagents themselves and their hydrothermal derivatives will not be adsorbed on the surface of the copper nanowires to significantly change their morphology and size.

[0018] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the volume of the reaction solution in step 3 is 50mL to 70mL. In the present invention, the volume of the reaction solution is controlled to ensure that the hydrothermal reduction reaction is carried out in a conventional reactor of 100mL. A reactor with too large a volume may reduce the morphology and size consistency of the product copper nanowires.

[0019] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the temperature of the hydrothermal reduction reaction in step 3 is 120°C and the time is 10h. The present invention controls the temperature of the appropriate hydrothermal reduction reaction so that the copper hydroxide precursor can be completely reduced to copper element, and controls the appropriate time to ensure that the reduction reaction is fully carried out, so as to prevent the reduction reaction from being unable to proceed when the reaction temperature is too low, and the increase in the reaction temperature will cause the uniformity of the copper nanowires to deteriorate. Reacting above 180°C will cause the excess reducing agent to be carbonized into carbon nanoparticles. The hydrothermal reduction reaction for 5h and longer can obtain copper nanowires with a complete copper phase. The longer the time, the more uniform the morphology of the copper nanowires, but no more gain will be generated when it is more than 10h.

[0020] The above-mentioned method for preparing ultra-long copper nanowires is characterized in that the drying in step 4 is vacuum drying at a temperature of 50°C to 60°C for more than 10 hours. In the present invention, the copper nanowires have an extremely high specific surface area, and a slight increase in temperature will cause oxidation of the surface, so the drying temperature should not be too high.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. In the present invention, a copper hydroxide precursor is formed by the reaction of hydroxide and copper ions in an aqueous phase system, and then the precursor is reduced to elemental copper through a hydrothermal reduction reaction under the action of a reducing agent. The added organic surfactant is adsorbed on the surface of the copper hydroxide precursor and the copper nanowires, so that the final product copper nanowires are longer, thinner and more dispersed, and other non-nanowire morphologies are prevented from being formed during the growth process. The chloride ions in the sodium chloride can etch defects such as protrusions and burrs of the copper nanowires during the growth process. The two work together to ensure that ultra-long and ultra-thin copper nanowires are obtained. By controlling the mass concentrations of the organic surfactant and sodium chloride, the formation of the copper nanowires is guaranteed to have a maximum gain, and the obtained copper nanowires are ensured to be easy to be cleaned and purified with deionized water, thereby reducing the preparation cost and reducing the emission of polluting products.

[0023] 2. All the raw materials used in the present invention are easily soluble in solvent water, and only a small amount of organic surfactant needs to be added, making the product very easy to clean.

[0024] 3. The entire reaction of the present invention does not require large / expensive instruments and equipment, and only requires a conventional hydrothermal reactor to carry out the experiment. The reaction cycle is short and easy to prepare on a large scale.

[0025] 4. The reaction of the present invention is a simple liquid phase coprecipitation reaction and hydrothermal reduction reaction. The sodium hydroxide precipitant and the reducing agents such as ascorbic acid, sodium ascorbate, glucose, cysteine, arginine, threonine, proline, and serine will not be converted into polluting substances, nor will toxic and harmful gas, liquid, and solid products be formed, which is more environmentally friendly.

[0026] 5. The ultra-long copper nanowires of the present invention can be used as low-cost metal nano-conductive fillers for flexible printed electronics.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a flow chart of the preparation of ultra-long copper nanowires in the present invention.

[0029] Figure 2 This is a low-magnification SEM image of the ultra-long copper nanowires prepared in Example 1 of the present invention.

[0030] Figure 3 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in Example 1 of the present invention.

[0031] Figure 4 This is the XRD pattern of the ultra-long copper nanowires prepared in Example 1 of the present invention.

[0032] Figure 5This is a low-magnification SEM image of the ultra-long copper nanowires prepared in Example 2 of the present invention.

[0033] Figure 6 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in Example 2 of the present invention.

[0034] Figure 7 This is the XRD pattern of the ultra-long copper nanowires prepared in Example 2 of the present invention.

[0035] Figure 8 This is a low-magnification SEM image of the ultra-long copper nanowires prepared in Example 3 of the present invention.

[0036] Fig. 9 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in Example 3 of the present invention.

[0037] Fig.10 This is the XRD pattern of the ultra-long copper nanowires prepared in Example 3 of the present invention.

[0038] Fig.11 This is a low-magnification SEM image of the ultra-long copper nanowires prepared in Example 4 of the present invention.

[0039] Fig.12 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in Example 4 of the present invention.

[0040] Fig.13 This is the XRD pattern of the ultra-long copper nanowires prepared in Example 4 of the present invention.

[0041] Fig.14 This is a low-magnification SEM image of the ultra-long copper nanowires prepared in Example 5 of the present invention.

[0042] Fig.15 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in Example 5 of the present invention.

[0043] Fig.16 This is the XRD pattern of the ultra-long copper nanowires prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0044] Figure 1 is a flow chart of the preparation of ultra-long copper nanowires in the present invention, from Figure 1 It can be seen that the present invention first dissolves copper chloride, sodium chloride and an organic surfactant in deionized water, stirs evenly to obtain a mixed solution, then adds sodium hydroxide to the mixed solution, stirs for reaction, and obtains a copper hydroxide precursor suspension, then adds a reducing agent to the copper hydroxide precursor suspension and performs a hydrothermal reduction reaction, and finally washes and dries the product obtained after the hydrothermal reduction reaction to obtain ultra-long copper nanowires.

[0045] Example 1

[0046] This embodiment includes the following steps:

[0047] Step 1, dissolving copper chloride, sodium chloride and octadecyltrimethylammonium chloride in deionized water, and stirring to form a mixed solution; the volume of the mixed solution is 43 mL, the mass concentration of copper chloride in the mixed solution is 1 g / L, the mass concentration of sodium chloride is 0.1 g / L, and the mass concentration of octadecyltrimethylammonium chloride is 1 g / L;

[0048] Step 2: Add 5 mL of 50 g / L sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, and stir to react for 10 min to obtain a copper hydroxide precursor suspension;

[0049] Step 3: Add 2 mL of an ascorbic acid aqueous solution with a mass concentration of 10 g / L to the copper hydroxide precursor suspension obtained in step 2, then stir evenly to form a 50 mL reaction solution, and perform a hydrothermal reduction reaction at 120° C. for 10 h;

[0050] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried at 50° C. to 60° C. for more than 10 hours to obtain ultra-long copper nanowires.

[0051] Figure 2 is a low-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment, Figure 3 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment. Figure 2 and Figure 3 It can be seen from the figure that the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 200 nm.

[0052] Figure 4 is the XRD pattern of the ultra-long copper nanowires prepared in this embodiment. Figure 4 It can be seen that the ultra-long copper nanowires prepared in this embodiment have high purity and are a single copper phase.

[0053] In this embodiment, the organic surfactant can also be one or more of dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride and eicosyltrimethylammonium chloride, and the reducing agent can also be one or more of green reducing agents such as ascorbic acid, sodium ascorbate, glucose, cysteine, arginine, threonine, proline, serine, etc.

[0054] Example 2

[0055] This embodiment includes the following steps:

[0056] Step 1, dissolving copper chloride, sodium chloride and eicosyltrimethylammonium chloride in deionized water, and stirring to form a mixed solution; the volume of the mixed solution is 35 mL, the mass concentration of copper chloride in the mixed solution is 10 g / L, the mass concentration of sodium chloride is 1 g / L, and the mass concentration of eicosyltrimethylammonium chloride is 10 g / L;

[0057] Step 2: Add 10 mL of 50 g / L sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, and stir to react for 10 min to obtain a copper hydroxide precursor suspension;

[0058] Step 3: Add 5 mL of an ascorbic acid aqueous solution with a mass concentration of 10 g / L to the copper hydroxide precursor suspension obtained in step 2, then stir evenly to form a 50 mL reaction solution, and perform a hydrothermal reduction reaction at 120° C. for 10 h;

[0059] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried at 50° C. to 60° C. for more than 10 hours to obtain ultra-long copper nanowires.

[0060] After testing, the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 250 nm. The prepared ultra-long copper nanowires have high purity and are a single copper phase.

[0061] Figure 5 is a low-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment, Figure 6 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment. Figure 5 and Figure 6 It can be seen from the figure that the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 250 nm.

[0062] Figure 7 is the XRD pattern of the ultra-long copper nanowires prepared in this embodiment. Figure 7 It can be seen that the ultra-long copper nanowires prepared in this embodiment have high purity and are a single copper phase.

[0063] Example 3

[0064] This embodiment includes the following steps:

[0065] Step 1, dissolving copper chloride, sodium chloride and hexadecyltrimethylammonium chloride in deionized water, and stirring to form a mixed solution; the volume of the mixed solution is 43 mL, the mass concentration of copper chloride in the mixed solution is 1 g / L, the mass concentration of sodium chloride is 0.1 g / L, and the mass concentration of hexadecyltrimethylammonium chloride is 2 g / L;

[0066] Step 2: Add 5 mL of 50 g / L sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, and stir to react for 10 min to obtain a copper hydroxide precursor suspension;

[0067] Step 3: Add 2 mL of an ascorbic acid aqueous solution with a mass concentration of 10 g / L to the copper hydroxide precursor suspension obtained in step 2, then stir evenly to form a 50 mL reaction solution, and perform a hydrothermal reduction reaction at 120° C. for 5 h;

[0068] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried at 50° C. to 60° C. for more than 10 hours to obtain ultra-long copper nanowires.

[0069] After testing, the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 200 nm. The prepared ultra-long copper nanowires have high purity and are a single copper phase.

[0070] Figure 8 is a low-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment, Fig. 9 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment. Figure 8 and Fig. 9 It can be seen from the figure that the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 200 nm.

[0071] Fig.10 is the XRD pattern of the ultra-long copper nanowires prepared in this embodiment. Fig.10 It can be seen that the ultra-long copper nanowires prepared in this embodiment have high purity and are a single copper phase.

[0072] Example 4

[0073] This embodiment includes the following steps:

[0074] Step 1, dissolving copper chloride, sodium chloride and octadecyltrimethylammonium chloride in deionized water, and stirring to form a mixed solution; the volume of the mixed solution is 50.5 mL, the mass concentration of copper chloride in the mixed solution is 5 g / L, the mass concentration of sodium chloride is 1 g / L, and the mass concentration of octadecyltrimethylammonium chloride is 2 g / L;

[0075] Step 2: Add 7.5 mL of 50 g / L sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, and stir to react for 10 min to obtain a copper hydroxide precursor suspension;

[0076] Step 3: Add 2 mL of an ascorbic acid aqueous solution with a mass concentration of 10 g / L to the copper hydroxide precursor suspension obtained in step 2, then stir evenly to form a 60 mL reaction solution, and perform a hydrothermal reduction reaction at 180° C. for 10 h;

[0077] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried at 50° C. to 60° C. for more than 10 hours to obtain ultra-long copper nanowires.

[0078] After testing, the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 200 nm. The prepared ultra-long copper nanowires have high purity and are a single copper phase.

[0079] Fig.11 is a low-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment, Fig.12 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment. Fig.11 and Fig.12 It can be seen from the figure that the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 200 nm.

[0080] Fig.13 is the XRD pattern of the ultra-long copper nanowires prepared in this embodiment. Fig.13 It can be seen that the ultra-long copper nanowires prepared in this embodiment have high purity and are a single copper phase.

[0081] Example 5

[0082] This embodiment includes the following steps:

[0083] Step 1, dissolving copper chloride, sodium chloride and octadecyltrimethylammonium chloride in deionized water, and stirring to form a mixed solution; the volume of the mixed solution is 64 mL, the mass concentration of copper chloride in the mixed solution is 1 g / L, the mass concentration of sodium chloride is 0.5 g / L, and the mass concentration of octadecyltrimethylammonium chloride is 1 g / L;

[0084] Step 2: Add 5 mL of 50 g / L sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, and stir to react for 10 min to obtain a copper hydroxide precursor suspension;

[0085] Step 3: add 1 mL of an ascorbic acid aqueous solution with a mass concentration of 10 g / L to the copper hydroxide precursor suspension obtained in step 2, then stir evenly to form a 70 mL reaction solution, and perform a hydrothermal reduction reaction at 160° C. for 8 h;

[0086] Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried at 50° C. to 60° C. for more than 10 hours to obtain ultra-long copper nanowires.

[0087] After testing, the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 250 nm. The prepared ultra-long copper nanowires have high purity and are a single copper phase.

[0088] Fig.14 is a low-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment, Fig.15 This is a high-magnification SEM image of the ultra-long copper nanowires prepared in this embodiment. Fig.14 and Fig.15 It can be seen from the figure that the ultra-long copper nanowires prepared in this embodiment are typical highly dispersed one-dimensional nanowire morphology, with a length generally above 50 μm and a diameter of 100 nm to 250 nm.

[0089] Fig.16 is the XRD pattern of the ultra-long copper nanowires prepared in this embodiment. Fig.16 It can be seen that the ultra-long copper nanowires prepared in this embodiment have high purity and are a single copper phase.

[0090] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing ultra-long copper nanowires, characterized in that: The method comprises a liquid phase coprecipitation reaction and a hydrothermal reduction reaction, and specifically comprises the following steps: Step 1, dissolving copper chloride, sodium chloride and an organic surfactant in deionized water, stirring evenly to obtain a mixed solution; the volume of the mixed solution is 35mL-64mL, the mass concentration of copper chloride in the mixed solution is 1g / L-10g / L, the mass concentration of sodium chloride is 0.1g / L-1g / L, and the mass concentration of the organic surfactant is 1g / L-10g / L; Step 2: Add 5 mL to 10 mL of sodium hydroxide aqueous solution dropwise to the mixed solution obtained in step 1, stir and react to obtain a copper hydroxide precursor suspension; Step 3, adding 1 mL to 5 mL of reducing agent aqueous solution to the copper hydroxide precursor suspension obtained in step 2, then stirring evenly to form a reaction solution, and performing a hydrothermal reduction reaction; the temperature of the hydrothermal reduction reaction is 120° C. to 180° C., and the time is 5 h to 10 h; Step 4: The product obtained after the hydrothermal reduction reaction in step 3 is washed with deionized water and anhydrous ethanol in sequence, and then dried to obtain ultra-long copper nanowires.

2. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The organic surfactant in step 1 is one or more of dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride and eicosyltrimethylammonium chloride.

3. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The mass concentration of the sodium hydroxide aqueous solution in step 2 is 50 g / L, the volume of the added sodium hydroxide aqueous solution is 5 mL, and the stirring reaction time is 10 min.

4. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The mass concentration of the reducing agent aqueous solution in step 3 is 10 g / L, and the amount of the reducing agent aqueous solution added is 2 mL.

5. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The reducing agent in step 3 is one or more of ascorbic acid, sodium ascorbate, glucose, cysteine, arginine, threonine, proline and serine.

6. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The volume of the reaction solution in step 3 is 50 mL to 70 mL.

7. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The temperature of the hydrothermal reduction reaction in step 3 is 120° C. and the time is 10 h.

8. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The drying in step 4 is vacuum drying at a temperature of 50° C. to 60° C. for more than 10 hours.

9. The method for preparing ultra-long copper nanowires according to claim 1, characterized in that: The length of the ultra-long copper nanowire in step 4 is not less than 50 μm.

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