WO2018062090A1 - Metal nanowire - Google Patents

Abstract

The present invention provides a metal nanowire which has a sufficiently large specific surface area. The present invention relates to a metal nanowire which is characterized by having a specific surface area of 15 m²/g or more as determined by a nitrogen gas adsorption method.

Description

Metal nanowires

The present invention relates to a metal nanowire, particularly a metal nanowire having a large specific surface area.

Some metals have a catalytic function, a deodorizing function, an antibacterial function, and the like. In recent years, these nanomaterials have been studied for use as a catalyst, a deodorizing agent, an antibacterial agent, and the like. In addition, since metals have redox ability and conductivity, it has been studied to use metal nanomaterials as electrodes and sensors. These applications are required to have a large specific surface area in order to enhance the function.

Nickel is known as a metal having a catalytic function. For example, Patent Documents 1 to 3 disclose nickel nanowires obtained by reducing metal ions while applying a magnetic field. However, the nickel nanowires of Cited Documents 1 to 3 have a limited specific surface area and have limited applications.

International Publication No. 2014/147785 International Publication No. 2015/163258 Pamphlet JP 2016-135920 A

An object of the present invention is to provide a metal nanowire having a sufficiently large specific surface area.

As a result of intensive studies to solve such problems, the present inventors reduced specific metal surface area by reducing metal ions while applying a magnetic field in water containing carboxymethyl cellulose having a specific viscosity at a specific concentration. Has found that a wide metal nanowire can be obtained, and has reached the present invention.

The gist of the present invention is as follows.
<1> A metal nanowire having a specific surface area of 15 m ² / g or more by a nitrogen gas adsorption method.
<2> The metal nanowire according to <1>, wherein the metal is nickel.
<3> The metal nanowire according to <1> or <2>, wherein the metal nanowire has an average fiber diameter of 50 to 300 nm.
<4> The metal nanowire according to any one of <1> to <3>, wherein the metal nanowire has an average length of 5 to 100 μm.
<5> A dispersion liquid comprising the metal nanowire according to any one of <1> to <4>.
<6> A structure comprising the metal nanowire according to any one of <1> to <4>.
<7> The method for producing metal nanowires according to any one of <1> to <4>, wherein metal ions are reduced in an aqueous solution of a carboxymethylcellulose salt.
<8> The method for producing metal nanowires according to <7>, wherein the carboxymethylcellulose salt is a carboxymethylcellulose salt having a 1% by mass aqueous solution having a viscosity of 1000 to 9000 mPa · s.
<9> The method for producing metal nanowires according to <7> or <8>, wherein the concentration of the carboxymethylcellulose salt is 0.5% by mass or more and less than 1.0% by mass.
<10> Reduction of metal ions while applying a magnetic field in an aqueous solution containing a carboxymethyl cellulose salt having a viscosity of 1000 to 9000 mPa · s in a 1% by mass aqueous solution at a concentration of 0.5% by mass or more and less than 1.0% by mass. Metal nanowires obtained by the method for producing metal nanowires.

According to the present invention, a metal nanowire having a large specific surface area can be provided. The metal nanowire of this invention can be used suitably as a catalyst, a deodorizing agent, and an antibacterial agent, and can also be used suitably for a sensor and a battery electrode.

It is the image which image | photographed the metal nanowire obtained in Example 1 with the scanning electron microscope.

[Metal nanowires]
Since the metal nanowire of the present invention has a protrusion structure having a large number of protrusions on the surface, the metal nanowire has a wide specific surface area. The protruding direction of the large number of protrusions is not particularly limited. The protruding directions of the multiple protrusions may be independently, for example, the substantially radial direction of the metal nanowire in a cross section perpendicular to the longitudinal direction of the metal nanowire, or the substantially radial direction and the metal nanowire The resultant force direction may be the longitudinal direction. The protrusion lengths of the multiple protrusions are not particularly limited. The protruding lengths of a large number of protrusions are usually independently R (nm) or less, where R (nm) is an average fiber diameter described later.

The specific surface area of the metal nanowires of the present invention is ^{15 m} 2 / g or more, preferably ^{20 m} 2 / g or more, more preferably ^{30 m} 2 / g or more, more preferably ^{40 m} 2 / g or more, and most preferably ^{50 m} 2 / g or more. The specific surface area can be measured according to an analysis method described later. When the specific surface area is 50 m ² / g or more, the specific surface area is about the same as that of an adsorbent such as magnesia and titania, so that it can be most suitably used as a catalyst. The upper limit of the specific surface area of the metal nanowire of the present invention is not particularly limited, and the specific surface area is usually 200 m ² / g or less, particularly 100 m ² / g or less.

The average fiber diameter of the metal nanowire of the present invention is usually 50 to 300 nm, preferably 50 to 200 nm, more preferably 60 to 150 nm, still more preferably 65 to 150 nm, particularly preferably 65 to 100 nm, and most preferably 65. ~ 95 μm. When the average fiber diameter is less than 50 nm, it becomes easy to cut, so the length is not constant, and various performances may be affected. The average length of the metal nanowire of the present invention is usually about 5 to 100 μm, preferably 5 to 50 μm, more preferably 6 to 50 μm, still more preferably 6 to 40 μm, and most preferably 6 to 30 μm. . When the average length is less than 5 μm, the strength may be weakened when a molded body (particularly a nonwoven fabric) is used. In addition, the average fiber diameter and average length of metal nanowire can be measured according to the analysis method mentioned later.

In the present invention, the fiber diameter is the diameter of the nanowire including the protrusion height of the protrusion, which means the diameter in a vertical cross section with respect to the longitudinal direction of the nanowire, and SEM image of the nanowire (scanning electron microscope image (photograph )). The protruding height of the protruding portion is the height of the protruding portion in the vertical cross section with respect to the longitudinal direction of the nanowire. In the metal nanowire of the present invention, since a large number of protrusions exist on the surface without gaps, the two points defining the line segment indicating the diameter on the image are usually points on the outline of the protrusion. Specifically, the minimum value of the above-mentioned diameter is measured as the minimum fiber diameter in a single nanowire not at the end portion, and the average value of the minimum fiber diameters of arbitrary 300 nanowires is defined as the average fiber diameter. The end portion is within 100 nm from the end of the nanowire.

The metal constituting the metal nanowire of the present invention is not particularly limited, but in the present invention, since the metal nanowire is produced in a magnetic field, a ferromagnetic metal such as nickel, iron, cobalt, and gadolinium is preferable, inexpensive and practical. Nickel is more preferable because of its high properties.

[Production method of metal nanowires]
The metal nanowire of the present invention can be produced by reducing metal ions while applying a magnetic field (magnetic circuit) in an aqueous solution containing a specific concentration of carboxymethyl cellulose salt having a specific viscosity.

The exemplified manufacturing method is established by three steps including generation of metal particles, growth to nanowires, and construction of protrusion structures. Formation of metal particles occurs by spontaneous generation of metal particle nuclei by a reducing agent or particle formation using palladium nuclei and platinum nuclei. The generated metal particles grow into nanowires while being connected by an external factor such as a magnetic field. Then, a reduction reaction of metal ions occurs on the surface of the nanowire to construct a protruding structure. The difference from Patent Documents 1 to 3 is the third step. In the present invention, in order to construct a protrusion structure, a complex formation technique that delays the reduction reaction of some metal ions and a viscosity control of a reaction solvent that suppresses bonding and aggregation between nanowires are important. Therefore, a reaction solvent containing a specific carboxymethyl cellulose salt at a specific concentration is required.

The carboxymethyl cellulose salt is a carboxymethyl cellulose salt having a lower limit of viscosity of 1000 mPa · s or more when an aqueous solution in which the carboxymethyl cellulose salt is dissolved in water at a concentration of 1% by mass is measured at 25 ° C. using a B-type viscometer. is there. From the viewpoint of further increasing the specific surface area of the metal nanowire, the viscosity of the carboxymethyl cellulose salt is preferably 2000 mPa · s or more, more preferably 2500 mPa · s or more, and 3000 mPa · s or more. Further preferred. When the viscosity is less than 1000 mPa · s, metal nanowires having a large specific surface area may not be generated. On the other hand, the upper limit of the viscosity when an aqueous solution obtained by dissolving the carboxymethyl cellulose salt in water at a concentration of 1% by mass at 25 ° C. using a B-type viscometer is 9000 mPa · s or less, and the ratio of metal nanowires From the viewpoint of further increasing the surface area, it is preferably 8500 mPa · s or less, more preferably 8000 mPa · s or less, and even more preferably 5000 mPa · s or less. When the viscosity exceeds 9000 mPa · s, nanowires may not be generated.

The concentration of the carboxymethyl cellulose salt is 0.5% by mass or more and less than 1.0% by mass with respect to the total amount of the reaction solution, and 0.5 to 0.98% by mass from the viewpoint of further increasing the specific surface area of the metal nanowires. Preferably, it is 0.6 to 0.98% by mass, more preferably 0.7 to 0.98% by mass, and even more preferably 0.7 to 0.8% by mass. Is most preferred. When the concentration of the carboxycellulose salt is less than 0.5% by mass and when it is 1% by mass or more, metal nanowires having a large specific surface area may not be generated in any case.

Examples of the carboxymethyl cellulose salt include a sodium salt and a calcium salt. Among them, a sodium salt is more preferable because it is inexpensive, highly practical, and easily undergoes salt exchange.

As the metal ion supplier, a metal salt is preferable because it is easily dissolved in an aqueous solvent. Examples of metal salts include metal chlorides, sulfates, nitrates, and acetates.

The preferred concentration of the metal ion varies depending on the metal species, but is usually 10 to 50 μmol / g based on the total amount of the reaction solution. When the metal is particularly nickel, the concentration of metal ions is preferably 20 to 30 μmol / g, more preferably 23 to 27 μmol / g, based on the total amount of the reaction solution, from the viewpoint of further increasing the specific surface area of the metal nanowires. It is more preferable. When the metal is nickel, when the concentration of metal ions is less than 20 μmol / g, and when it exceeds 30 μmol / g, it is difficult to produce metal nanowires having a large specific surface area. “Μmol / g” means the number of moles per gram of the reaction solution (hereinafter the same).

Although it can be controlled by the type and / or concentration of the reducing agent described later, complex formation that forms complexes with metal ions in addition to carboxymethylcellulose salt to control the amount of metal ions used for growth into nanowires It is preferable to add an agent. By adding this complexing agent, three components are formed: metal ions that form metal particles, metal complexes that are consumed in the growth of nanowires, and metal complexes with carboxymethylcellulose that are used to build protrusion structures. Each process proceeds more appropriately.

Examples of complexing agents include citric acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, nitrilotriacetic acid, hydroxyethyliminodiacetic acid, hydroxyiminodisuccinic acid, aminotrimethylene. Examples include phosphonic acid, hydroxyethanephosphonic acid and salts thereof. Of these, trisodium citrate dihydrate is more preferable in view of solubility in the reaction solution. When using a complexing agent, the concentration is preferably 0.001 μmol / g or more, more preferably 0.001 to 50 μmol, based on the total amount of the reaction solution, from the viewpoint of further increasing the specific surface area of the metal nanowires. / G, more preferably 1 to 20 μmol / g.

The reaction solution may contain a nucleating agent at less than 0.07 μmol / g with respect to the total amount of the reaction solution. The nucleating agent generates noble metal nanoparticle nuclei with a diameter of several nanometers and promotes the generation of metal particles. Examples of the nucleating agent include salts of noble metals such as gold, silver, platinum, palladium, rhodium, iridium, ruthenium and osmium. Examples of the noble metal salt include chloroplatinic acid, chloroauric acid, and palladium chloride. For example, when nickel ions are reduced, palladium chloride that generates palladium nanoparticles, chloroplatinic acid that generates platinum nanoparticles, and the like are preferable. Of these, chloroplatinic acid is preferred because it is easy to form nuclei suitable for generation of metal nanowires. When a nucleating agent is used, the concentration is preferably 0.01 μmol / g or more, more preferably 0.01 to 0, relative to the total amount of the reaction solution, from the viewpoint of further increasing the specific surface area of the metal nanowires. 0.06 μmol / g.

As a method for reducing metal ions, it is preferable to use a reducing agent. Examples of the reducing agent include hydrazine, hydrazine monohydrate, ferrous chloride, hypophosphorous acid, borohydride, aminoboranes, lithium aluminum hydride, sulfites, hydroxylamines (for example, diethylhydroxylamine). ), Zinc amalgam, diisobutylaluminum hydride, hydroiodic acid, ascorbic acid, oxalic acid, formic acid, ferrous chloride, hypophosphorous acid, borohydride, aminoboranes, ascorbic acid, oxalic acid, formic acid It is done. When the metal ion is nickel ion, hydrazine or hydrazine monohydrate is preferable because of its high reducing power.

The concentration of the reducing agent varies depending on the type of reducing agent used and / or the metal to be reduced. For example, when nickel ions are reduced using hydrazine monohydrate, from the viewpoint of further increasing the specific surface area of the metal nanowires. The total amount of the reaction solution is preferably 1 to 500 μmol / g, more preferably 1 to 300 μmol / g, and still more preferably 200 to 300 μmol / g.

The reaction solvent is preferably composed mainly of water. When water is not the main component, the carboxycellulose salt may not dissolve. In the present invention, “having water as a main component” means that water is 80% by mass or more in the reaction solvent. You may add alcohol, such as methanol and isopropanol, to a reaction solvent as needed.

When reducing metal ions, it is preferable to control pH and reaction temperature. The preferred pH and reaction temperature vary depending on the reducing agent used. For example, when hydrazine monohydrate is used, the pH is preferably 11 to 12 from the viewpoint of further increasing the specific surface area of the metal nanowires. The temperature is preferably 70 to 100 ° C., particularly 75 to 90 ° C.

The time required for reduction of the metal ions is not particularly limited, but is usually about 10 minutes to 1 hour, and preferably 15 to 30 minutes from the viewpoint of further increasing the specific surface area of the metal nanowires.

As the magnetic field (magnetic flux density) applied when reducing metal ions, the central magnetic field of the reaction vessel is preferably 10 mT or more from the viewpoint of further increasing the specific surface area of the metal nanowire, and should be 10 mT to 1 T. Is more preferable, and 50 to 180 mT is more preferable. When the central magnetic field of the reaction vessel is less than 10 mT, metal nanowires may not be generated.

After completion of the reduction reaction, the metal nanowires can be obtained by purifying and collecting the metal nanowires by centrifugation, filtration, adsorption with a magnet, or the like.

[Usage]
The refined and recovered metal nanowires can be added to a solvent mainly composed of a highly polar solvent such as water and stirred to obtain a dispersion in which the metal nanowires are dispersed. The solvent of the dispersion is preferably an aqueous solvent mainly containing water. “Mainly containing water” means that water is 80% by mass or more of the total solvent. You may add alcohol, such as methanol and isopropanol, to an aqueous solvent as needed. The concentration of the metal nanowires in the dispersion is not particularly limited, but is preferably 0.01 to 2.0% by mass from the viewpoint of dispersibility.

The metal nanowire dispersion of the present invention may contain additives such as a binder, an antioxidant, a wetting agent, and a leveling agent.

The metal nanowire dispersion liquid of the present invention can produce a non-woven fabric structure by filtration and / or drying. The nonwoven fabric structure may be a nonwoven fabric made of metal nanowires. The metal nanowire dispersion liquid of the present invention can also be used to produce a two-dimensional or three-dimensional structure by coating a molded body. The molded body is a molded body made of a polymer, and may be a so-called support or substrate. At this time, the two-dimensional or three-dimensional structure may be a composite including a molded body and a metal nanowire-containing layer formed on the surface of the molded body. The metal nanowire-containing layer may be a non-woven fabric layer made of metal nanowires, a polymer layer in which metal nanowires are dispersed, or a polymer layer containing metal nanowire non-woven fabric. May be. Moreover, the metal nanowire of this invention can also be compounded with resin. “Compound” means to contain and disperse in a resin polymer.

Since the metal nanowire of the present invention has a large specific surface area, the wider the specific surface area, the more useful the performance is. For example, the metal nanowire of the present invention can be suitably used as a catalyst, a catalyst carrier, a deodorant, and an antibacterial agent, and can also be suitably used for a sensor and a battery electrode.

When the metal nanowire of the present invention is used as a catalyst, a catalyst carrier, a deodorant, and an antibacterial agent, the metal nanowire of the present invention has a surface plated with another metal different from the metal constituting the metal nanowire. Alternatively, the other metal may be supported. Further, semiconductivity may be added by oxidation or the like. For example, a catalyst having a promoter (co-catalyst) function can be obtained by supporting nanoparticles such as iron, chromium, molybdenum and the like on the metal nanowire of the present invention.

When the metal nanowire of the present invention is used as a battery electrode, for example, the battery electrode can be obtained by the following method using the above-described metal nanowire dispersion. First, a metal nanowire nonwoven fabric is obtained by filtering and drying the metal nanowire dispersion. After obtaining the metal nanowire nonwoven fabric, the thickness of the nonwoven fabric can be adjusted by pressing as desired. Subsequently, a battery electrode can be obtained by forming an electrode active material layer on the surface of the metal nanowire nonwoven fabric (the surface of each metal nanowire). Such a battery electrode can be used as a flexible electrode.

The method for forming the electrode active material layer is not particularly limited, and a known method for forming the electrode active material layer can be used. For example, the surface of a metal nanowire nonwoven fabric is oxidized to form a metal oxide film, which can be used as an electrode active material layer. It is known that oxides of metals constituting the metal nanowires of the present invention, for example, oxides of nickel, iron, cobalt, and gadolinium, react with lithium at a higher capacity than conventional carbon materials. . Since the metal nanowire of the present invention has a sufficiently large specific surface area, the battery electrode using the metal nanowire (nonwoven fabric) of the present invention can perform the redox reaction more efficiently. The battery electrode using the metal nanowire (nonwoven fabric) of the present invention is useful as, for example, a negative electrode or a positive electrode (particularly a negative electrode) of a lithium ion secondary battery.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

1. Evaluation Method (1) Average Fiber Diameter of Metal Nanowire The metal nanowires obtained in each of the examples and comparative examples were photographed at an observation magnification of 50,000 times using a scanning electron microscope.
From the obtained image, the minimum fiber diameter of each metal nanowire was measured for 300 metal nanowires randomly selected in any 10 fields of 3 μm × 3 μm, and the average fiber diameter was obtained by averaging them. It was. A scanning electron microscope image of the metal nanowire obtained in Example 1 is shown in FIG.

(2) Average length of metal nanowires The metal nanowires obtained in each of the examples and comparative examples were photographed at 1000 to 4000 times using a scanning electron microscope.
From the obtained images, the lengths of 200 metal nanowires selected at random were measured, and averaged to determine the average length.

(3) Specific surface area of metal nanowires Using about 100 mg of metal nanowires obtained in each of the examples and comparative examples, the amount of nitrogen gas adsorbed was measured by the nitrogen gas adsorption method. The specific surface area was calculated by the formula.

2. Ingredient (1) Carboxymethylcellulose sodium salt / Serogen MP-60
Viscosity when a solution of 1% by mass dissolved in water, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., was measured at 25 ° C. using a B-type viscometer = 10000 to 15000 mPa · s
・ Serogen BSH-12
Viscosity when a solution of 1% by mass dissolved in water, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., was measured at 25 ° C. using a B-type viscometer = 6000 to 8000 mPa · s
・ Serogen BSH-6
Viscosity when a solution of 1% by mass dissolved in water, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was measured at 25 ° C. using a B-type viscometer = 3000 to 4000 mPa · s
・ Serogen BS
Viscosity when measured with a B-type viscometer at 25 ° C from a solution dissolved in water at a concentration of 1% by mass, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. = 350 to 500 mPa · s

Example 1
Nickel chloride hexahydrate 0.59 g (2.48 mmol), trisodium citrate dihydrate 0.28 g (0.93 mmol), chloroplatinic acid hexahydrate 0.29 mg (5.00 μmol), cellogen BSH −6 0.75 g was dissolved in water. Further, a 5% aqueous sodium hydroxide solution was added dropwise to adjust the pH to 11.5, and water was added so that the total amount became 75 g to prepare a nickel ion solution.
On the other hand, 1.25 g (25.0 mmol) of hydrazine monohydrate is mixed with water, and 5% aqueous sodium hydroxide solution is added dropwise to adjust the pH to 11.5 so that the total amount becomes 25 g. Water was added to make a reducing agent solution.
Both the nickel ion solution and the reducing agent solution were heated to 80 to 85 ° C., then mixed while maintaining the temperature, a 100 mT magnetic field was applied, and a reduction reaction was performed for 20 minutes.
Then, it washed and collect | recovered by filtration and vacuum-dried and obtained nickel nanowire.

Examples 2-3 and Comparative Examples 2-3, 5 and 7-9
Except changing the kind and density | concentration of carboxymethylcellulose salt as Table 1, operation similar to Example 1 was performed and the nickel nanowire was obtained.

Comparative Example 1
1.19 g (5.00 mmol) of nickel chloride hexahydrate, 0.55 g (1.86 mmol) of trisodium citrate dihydrate, 5.18 mg (0.01 mmol) of chloroplatinic acid hexahydrate in water Dissolved. Further, a 5% aqueous sodium hydroxide solution was added dropwise to adjust the pH to 12.5, and water was added so that the total amount became 75 g to prepare a nickel ion solution.
On the other hand, 2.50 g (50.0 mmol) of hydrazine monohydrate is mixed with water, and 5% aqueous sodium hydroxide solution is added dropwise to adjust the pH to 12.5 so that the total amount becomes 25 g. Water was added to make a reducing agent solution.
Both the nickel ion solution and the reducing agent solution were heated to 80 to 85 ° C., then mixed while maintaining the temperature, a magnetic field of 100 mT was applied, and a reduction reaction was performed for 15 minutes.
Then, it washed and collect | recovered by filtration and vacuum-dried and obtained nickel nanowire.

Comparative Examples 4 and 6
Except for changing the kind and concentration of the carboxymethylcellulose salt as shown in Table 1, the same operation as in Example 1 was performed, but due to the high-viscosity reaction field, the movement of the generated nickel particles was restricted, and the nickel nanowires Could not get.

Table 1 shows the production conditions and evaluation results of the metal nanowires obtained in each of the examples and comparative examples.

The nickel nanowires of Examples 1 to 3 had a large number of protrusions on the surface, and the specific surface area was 15 m ² / g or more. Therefore, it is considered that it can be suitably used for a catalyst, a deodorant, an antibacterial agent, a sensor, a battery electrode, and the like. Further, in Example 1, the specific surface area is 50 m ² / g or more, the fiber length of the nanowire is sufficient, and the nonwoven fabric composed of the nanowire is not easily detached even when immersed in water. It was an excellent one.

Comparative Example 1 is an additional test of Example 1 of Patent Document 1. Since the carboxymethyl cellulose salt was not added, the specific surface area was less than 15 m ² / g.
Comparative Examples 2 and 3 are supplementary tests of Examples 1 and 2 of Patent Document 3, respectively.
In Comparative Examples 2, 5, and 7, the viscosity of the added carboxymethyl cellulose salt was too low, and thus the specific surface area was less than 15 m ² / g.
In Comparative Example 3, since the addition concentration of the carboxymethylcellulose salt was high, growth inhibition of nanowires occurred due to viscosity, the structure of the protrusion structure was insufficient, and the specific surface area was less than 15 m ² / g.
In Comparative Example 8, since the addition concentration of the carboxymethylcellulose salt was low, it was considered that nickel ions were insufficient for the construction of the protrusion structure, and the specific surface area was less than 15 m ² / g.
In Comparative Example 9, since the viscosity of the added carboxymethyl cellulose salt was too high, the specific surface area was less than 15 m ² / g, and the average length of the nanowires was short.

The metal nanowire of the present invention is useful for the production of, for example, a catalyst, a catalyst carrier, a deodorant, and an antibacterial agent.

Claims (10)

A metal nanowire having a specific surface area of 15 m ² / g or more by a nitrogen gas adsorption method. The metal nanowire according to claim 1, wherein the metal is nickel. The metal nanowire according to claim 1 or 2, wherein the metal nanowire has an average fiber diameter of 50 to 300 nm. 4. The metal nanowire according to claim 1, wherein the metal nanowire has an average length of 5 to 100 μm. A dispersion liquid comprising the metal nanowire according to any one of claims 1 to 4. A structure comprising the metal nanowire according to any one of claims 1 to 4. The method for producing metal nanowires according to any one of claims 1 to 4, wherein metal ions are reduced in an aqueous solution of carboxymethylcellulose salt. The method for producing metal nanowires according to claim 7, wherein the carboxymethyl cellulose salt is a carboxymethyl cellulose salt having a 1% by mass aqueous solution having a viscosity of 1000 to 9000 mPa · s. The method for producing metal nanowires according to claim 7 or 8, wherein the concentration of the carboxymethylcellulose salt is 0.5 mass% or more and less than 1.0 mass%. Metal nano-particles that reduce metal ions while applying a magnetic field in an aqueous solution containing a carboxymethyl cellulose salt having a viscosity of 1000 to 9000 mPa · s in a 1% by mass aqueous solution at a concentration of 0.5% by mass or more and less than 1.0% by mass. Metal nanowires obtained by the wire manufacturing method.

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