A method and apparatus for preparing metal nanowires

Abstract

The application provides a preparation method and device of metal nanowires, and belongs to the field of nanometer metal wire synthesis. First, an alloy precursor is prepared, the alloy precursor is arranged as an electrode in a hollow container with a through hole, then a radio frequency matching device is connected at the part of the electrode outside the through hole of the hollow container, a radio frequency power source is connected with the radio frequency matching device, a grounding electrode is arranged around the outer wall of the hollow container, then a protective discharge gas is introduced into the hollow container through another through hole of the hollow container, and the gas flow is controlled, finally, the radio frequency power source is turned on, radio frequency power is applied to the electrode, plasma is generated at the electrode, and metal nanowires are obtained at the inner wall of the hollow container. The application also provides a device for realizing the above method. The above method does not need expensive equipment, the process is simple, does not need chemical reagents, is environmentally friendly and pollution-free, and is low in cost. The above method does not need expensive equipment, the process is simple, does not need chemical reagents, is environmentally friendly and pollution-free, and is low in cost.

Description

Technical Field

[0001] This invention belongs to the field of nanowire synthesis, and more specifically, relates to a method and apparatus for preparing metal nanowires. Background Technology

[0002] Metal nanowires possess excellent electrical conductivity, a large area-to-volume ratio, and superior mechanical properties, making them promising candidates for applications in energy storage and micro / nano flexible devices. Currently, the main methods for preparing metal nanowires are electrospinning and chemical synthesis. Electrospinning typically utilizes a composite of metal oxides or metal salts and polymers as a spinning precursor and requires multiple post-processing steps to obtain the metal nanowires. Chemical synthesis, on the other hand, usually requires numerous chemical reagents, high-temperature and high-pressure reaction equipment, and has a long synthesis cycle.

[0003] In view of the shortcomings of the existing technology, there is a need to develop a new method for preparing metal nanowires that does not require any chemical reagents or complex and expensive equipment, and can greatly reduce manufacturing costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method and apparatus for preparing metal nanowires. By designing a novel method, an alloy is used as an electrode, and atmospheric pressure radio frequency plasma is applied to the electrode to obtain nanowires prepared from the alloy used as the electrode. The above method does not require expensive equipment, the process is simple, no chemical reagents are required, it is environmentally friendly and pollution-free, and the cost is low.

[0005] To achieve the above objectives, the present invention provides a method for preparing metal nanowires, comprising the following steps:

[0006] S1: Preparation of alloy precursors

[0007] S2: The alloy precursor is placed as an electrode inside a hollow container with through holes.

[0008] S3: In step S2, an RF matching device is connected to the portion of the electrode located outside the through-hole of the hollow container. The RF power supply is connected to the RF matching device, and a grounding electrode is surrounded on the outer wall of the hollow container.

[0009] S4: Protective discharge gas is introduced into the hollow container through another through-hole, and the gas flow rate is controlled.

[0010] S5: Turn on the radio frequency power supply, apply radio frequency power to the electrodes, plasma will be generated at the electrodes, and metal nanowires will be obtained on the inner wall of the hollow container.

[0011] Furthermore, the hollow container has a through hole at the end. The vacuum container with the through hole at the end is a three-way quartz tube. The alloy precursor, which serves as the electrode, is inserted into one of the through holes of the three-way quartz tube. The second through hole is used as an air inlet, and the third through hole is used as an air outlet. During operation, the air outlet is sealed by liquid.

[0012] Furthermore, the protective discharge gas is a mixture of He and H2 or a mixture of Ar and H2, wherein the volume ratio of H2 in the two protective discharge gases is 1% to 5%.

[0013] Furthermore, the alloy precursor is a binary or multi-element alloy. The alloy precursor is represented as SM, where S is the element of the obtained nanowires, and M is the alloying element. Specifically, S is a low-melting-point metallic element, preferably Zn, Al, Mg, Sn, Cu, Ag, Au, etc.; M is the alloying element, preferably an element with a melting point higher than S, and is one or more of Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ti, V, Pt, Pd, Ru, Rh, Ir, W, Ta, Ge, and Si, and the phase diagram of the alloy precursor SM exhibits a solid-liquid coexistence region.

[0014] Furthermore, the diameter of the metal nanowires ranges from 50 nm to 200 nm.

[0015] Furthermore, the alloy precursor prepared in step S1 is in the shape of rod, bar, sheet, or strip to facilitate its use as an electrode and to be easily melted at high temperature in subsequent processes.

[0016] Furthermore, the power applied to the electrodes by the radio frequency power supply through the radio frequency matching device can melt the grain boundaries of the alloy precursor that serves as the electrode, forming a solid-liquid coexistence state.

[0017] Furthermore, the protective discharge gas is used to control the plasma temperature, and the flow rate of the protective discharge gas can be adjusted according to the plasma temperature.

[0018] According to a second aspect of the invention, an apparatus for implementing the above method is also provided, comprising an RF matching unit, an RF power supply, a three-way quartz tube, and a grounding electrode. The RF matching unit is connected to an alloy precursor used as an electrode. The alloy precursor is inserted into one through-hole of the three-way quartz tube. A protective discharge gas is introduced into another through-hole of the three-way quartz tube. The third through-hole of the three-way quartz tube is liquid-sealed. The grounding electrode is wound around the outer wall of the three-way quartz tube.

[0019] Furthermore, it also includes a mass flow meter, a gas storage tank, and a water seal device. The protective gas is contained in the gas storage tank. A mass flow meter is installed on the pipeline connecting the gas storage tank and the three-channel quartz tube to monitor the flow rate of the protective discharge gas. The third through hole of the three-channel quartz tube is immersed in the water seal device to be sealed.

[0020] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0021] 1. In the method of this invention, a radio frequency voltage is applied to an alloy electrode, and the atmosphere surrounding the alloy electrode is a protective discharge gas. Through discharge, atmospheric pressure radio frequency plasma is formed in the protective discharge gas at the alloy electrode, and the atmospheric pressure radio frequency plasma forms a high-voltage capacitive sheath on the surface of the alloy electrode. First, this high-voltage capacitive sheath causes the surface of the alloy electrode and its vicinity to rapidly rise to the highest temperature after the discharge begins, quickly heating the alloy to a solid-liquid coexistence region. The grain boundaries preferentially melt to form microchannels, while the area far from the metal surface maintains a lower temperature. Second, the high-voltage capacitive sheath has a strong electric field of up to 10 kV / cm pointing from the plasma region to the electrode surface. The molten alloy in the microchannels, after being charged, is directionally extracted under the action of the electric field force. Since less metal is melted at the interface and the microchannels are extremely narrow, the extracted metal wires form nanowires with a diameter of 50 nm to 200 nm. These nanowires are cooled before reaching the wall of the hollow container and deposited on the inner wall of the hollow container.

[0022] 2. In the method of the present invention, the alloy electrode is in direct contact with the radio frequency plasma. The radio frequency plasma can rapidly rise to the highest temperature after the discharge begins, and the dealloying process is quickly realized in a short time. The dealloyed alloy forms nanowires in the atmosphere. The operation process is simple, easy to implement, time-saving and efficient.

[0023] 3. The method of the present invention does not require any polluting and complex and expensive devices such as chemical reagents, vacuum systems, heating systems, and atmosphere protection systems, which greatly reduces equipment costs.

[0024] 4. The method of the present invention utilizes radio frequency plasma to prepare metal nanowires in one step without multiple steps and post-processing. It can obtain ultrafine metal nanowires with a diameter of about 100 nm in about 2 minutes. The operation process is simple, easy to implement, time-saving and efficient. Attached Figure Description

[0025] Figure 1 This is a flowchart of the metal nanowire preparation method provided in the embodiments of the present invention;

[0026] Figure 2 This is a schematic diagram of the zinc nanowire preparation apparatus provided in an embodiment of the present invention;

[0027] Figure 3 Scanning electron micrograph of the metal nanowires prepared in the embodiments of the present invention;

[0028] Figure 4Transmission electron micrograph of a single metal nanowire prepared in an embodiment of the present invention;

[0029] Figure 5 This is an X-ray diffraction pattern of a single metal nanowire prepared according to an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] The purpose of this invention is to provide a method and apparatus for preparing metal nanowires. By designing a novel method, an alloy is used as an electrode, and atmospheric pressure radio frequency plasma is applied to the electrode to obtain nanowires prepared from the alloy used as the electrode.

[0032] This invention utilizes the rapid heating effect of atmospheric pressure radio frequency plasma and the synergistic effect of the sheath electric field to achieve rapid fabrication of metal nanowires. According to multi-component alloy phase diagrams, most alloys, except for infinitely miscible metal alloys, exhibit a solid-liquid coexistence region. Multi-component alloys with specific compositions undergo non-equilibrium melting during rapid heating, forming a solid-liquid coexistence state. This invention leverages this characteristic; by rapidly heating the alloy precursor with atmospheric pressure radio frequency plasma, non-equilibrium melting occurs, preferentially melting at grain boundaries to form microchannels. Simultaneously, at the plasma boundary, due to the "instantaneous" electric field generated by the radio frequency power supply, mobile electrons undergo periodic motion within a space charge cloud composed of positive ions. High-mass ions are only affected by the time-averaged electric field. This periodic motion of the electron cloud generates a sheath near the electrode. Within this sheath, the average number of positive charges per cycle exceeds the number of negative charges, resulting in a net positive charge within the sheath region. The net charge generates a strong oscillating electric field in the sheath, pointing from the plasma towards the electrode. This field causes electrofluid instability fluctuations in the negatively charged molten liquid. When the electric field strength is high enough, these instability fluctuations are broken, and the molten alloy in the microchannel, after being charged, is directionally extracted under the action of the electric field force, overcoming surface tension. Because there is less molten metal at the interface and the microchannel is extremely narrow, the extracted metal wires form nanowires.

[0033] In this invention, the plasma temperature can be controlled by the radio frequency voltage and the protective discharge gas flow rate; under the same excitation voltage, the greater the flow rate, the lower the temperature. The sheath electric field strength can also be controlled by the radio frequency voltage. Where V0 is the amplitude of the radio frequency voltage, and ω is the angular frequency of the radio frequency voltage. This represents the sheath voltage; the higher the excitation voltage, the higher the sheath voltage. For alloy systems with different melting points, the critical electric field strength (corresponding to the radio frequency excitation voltage V) at which electrofluid jetting occurs is... c The results will vary depending on the surface tension of the melt. Therefore, during the experiment, it is necessary to use a higher gas flow and radio frequency voltage to excite the plasma, ensuring that the plasma temperature is below the alloy melting point (solid line). Then, the gas flow is reduced to allow the alloy temperature to rise rapidly to the solid-liquid coexistence region. After a period of time, metal nanowires are obtained.

[0034] Figure 1 This is a flowchart of the metal nanowire preparation method provided in the embodiments of the present invention. Figure 1 As can be seen, the method of the present invention mainly includes the following core steps:

[0035] S1: Preparation of an alloy precursor, the phase diagram of which exhibits a solid-liquid coexistence region. The alloy precursor is a binary or multi-element alloy. The alloy precursor is represented as SM, where S is the element of the obtained nanowires, and M is the alloying element. S is a low-melting-point metal element, preferably Zn, Al, Mg, Sn, Cu, Ag, Au, etc.; M is an alloying element, preferably a high-melting-point element, one or more of Cr, Mn, Fe, Co, Ni, Mo, Zr, Ti, V, Pt, Pd, Ru, Rh, Ir, W, Ta, Ge, and Si. The phase diagram of the alloy composition exhibits a solid-liquid coexistence region. The prepared alloy precursor is rod-shaped, bar-shaped, sheet-shaped, or strip-shaped to facilitate its use as an electrode and to allow for easy high-temperature melting in subsequent processes.

[0036] In practical engineering, the phase diagram of alloy precursors contains a solid-liquid coexistence region. Without this region, it would be impossible to prepare nanowires using the method of this invention. It is precisely within the temperature range corresponding to this solid-liquid coexistence region that the liquid metal is directionally extracted by an electric field, transforming into nanowires.

[0037] S2: The alloy precursor is placed as an electrode inside a hollow container with through holes.

[0038] S3: The portion of the electrode located outside the through-hole of the hollow container in step S2 is connected to an RF matching device. The RF power supply is connected to the RF matching device, and a grounding electrode is surrounded on the outer wall of the hollow container. The hollow container has through-holes at its ends. The vacuum container with through-holes at its ends is a three-way quartz tube. The alloy precursor, serving as the electrode, is inserted into one through-hole of the three-way quartz tube. The second through-hole serves as an air inlet, and the third through-hole serves as an air outlet. During operation, the air outlet is liquid-sealed.

[0039] S4: Introduce protective discharge gas into the hollow container through another through hole and control the gas flow rate. The protective discharge gas is a mixture of He and H2 or a mixture of Ar and H2. The volume ratio of H2 in the two protective discharge gases is 1% to 5%.

[0040] S5: The radio frequency (RF) power supply is turned on, applying RF power to the electrodes. Plasma is generated at the electrodes. Protective discharge gas is used to control the plasma temperature, and its flow rate can be adjusted according to the plasma temperature. The power applied to the electrodes by the RF power supply through the RF matching device melts the grain boundaries of the alloy precursor serving as the electrodes, forming a solid-liquid coexistence state. After a period of time, metallic nanowires with diameters ranging from 50 nm to 200 nm are obtained on the inner wall of the hollow container.

[0041] Figure 2 This is a schematic diagram of the zinc nanowire preparation apparatus provided in an embodiment of the present invention. As shown in the diagram, 1 is a He / H2 mixture, 2 is a mass flow meter, 3 is an RF matching device, 4 is an RF power supply, 6 is an RF electrode connected to the sample, 5 is a three-channel quartz tube, 7 is a grounding electrode (in this embodiment, the grounding electrode is a grounding tantalum foil electrode), and 8 is a water-sealing device. The RF matching device 3 is connected to the alloy precursor used as an electrode. The RF matching device 3 is connected to the RF power supply 4, which is connected to the RF electrode 6. The RF electrode 6 is connected to the alloy precursor. The alloy precursor is inserted into one through-hole of the three-channel quartz tube 5. The other through-hole of the three-channel quartz tube 5 is filled with a protective discharge gas, He / H2 mixture 1, which is placed in a gas storage tank. The third through-hole of the three-channel quartz tube 5 is liquid-sealed, and the grounding electrode is wrapped around the outer wall of the three-channel quartz tube 5. A mass flow meter 2 is installed on the pipeline connecting the gas storage tank and the three-channel quartz tube to monitor the flow rate of the protective discharge gas. The third through hole of the three-channel quartz tube 5 is immersed in the water sealing device 8, and the outer wall of the three-channel quartz tube 5 is wrapped with a grounding electrode 7.

[0042] In practical engineering, firstly, a zinc-copper alloy can be used as an electrode, inserted into a three-channel quartz tube and the tube opening sealed. A 13.56MHz RF matching circuit is then connected. The outside of the three-channel quartz tube is surrounded by a tantalum foil of equal length and grounded. The other end of the three-channel quartz tube is irrigated with deionized water to isolate oxygen. The inner diameter of the quartz tube is 1.5–6 mm, preferably 4 mm in a preferred embodiment, and the wall thickness is 0.5 mm–2 mm, preferably 1 mm in a preferred embodiment. Next, a He / H2 mixture is pre-introduced into the branch of the quartz tube for 1–3 minutes to purge air from the device. The H2 ratio is 1%–5%, preferably 2%, and the gas flow rate is controlled at 100–400 mL / min, preferably 200 mL / min. Finally, the RF power supply and matching circuit are turned on, and the power is adjusted to 60–100 W, preferably 80 W. The He / H2 mixture inside the quartz tube discharges to form atmospheric pressure RF plasma. After 1–5 minutes, zinc nanowires are collected on the wall of the quartz tube.

[0043] Example 1

[0044] (1) Insert the Zn-Cu (Cu and Zn atomic ratio of 1:5) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 2%.

[0045] (2) Turn on the radio frequency power supply and adjust the power to 80W. Radio frequency plasma will be generated near the alloy electrode. Quickly reduce the gas flow to 200mL / min. After 2 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material adhering to the inner wall of the quartz tube to obtain zinc nanowire powder. Its scanning electron microscope image is as follows: Figure 3 As shown, by Figure 3 As can be seen, it has a regular shape, with multiple nanowires twisted together. Its transmission electron microscope image is as follows: Figure 4 As shown, by Figure 4 It is known that the diameter of the nanowire is approximately 90 nm to 110 nm. Figure 5 The X-ray diffraction pattern of the single metal nanowire prepared in the embodiment of the present invention shows that it is indeed zinc based on its composition.

[0046] Example 2

[0047] (1) Insert the Al-Cu (Cu and Al atomic ratio of 1:9) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 3%.

[0048] (2) Turn on the radio frequency power supply and adjust the power to 85W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 150mL / min. After 2 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain aluminum nanowire powder. The diameter of the nanowire is about 100nm to 150nm.

[0049] Example 3

[0050] (1) Insert the Zn-Fe (Fe and Zn atomic ratio of 1:2) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 4%.

[0051] (2) Turn on the radio frequency power supply and adjust the power to 90W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 150mL / min. After 2 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain zinc nanowire powder. The diameter of the nanowire is about 120nm~160nm.

[0052] Example 4

[0053] (1) Insert the Cu-Ti (Cu and Ti atomic ratio of 9:1) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 1%.

[0054] (2) Turn on the radio frequency power supply and adjust the power to 95W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 100mL / min. After 4 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain copper nanowire powder. The diameter of the nanowire is 150nm~200nm.

[0055] Example 5

[0056] (1) Insert the Cu-Sn (Cu and Sn atomic ratio of 1:5) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 5%.

[0057] (2) Turn on the radio frequency power supply and adjust the power to 85W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 500mL / min. After 3 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain tin nanowire powder. The diameter of the nanowire is 50nm~90nm.

[0058] Example 6

[0059] (1) Insert the Ag-Zr (Ag and Zr atomic ratio of 7:3) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 2%.

[0060] (2) Turn on the radio frequency power supply and adjust the power to 95W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 150mL / min. After 3 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain silver nanowire powder. The diameter of the nanowire is 50nm~120nm.

[0061] Example 7

[0062] (1) Insert the Au-Si (Au and Si atomic ratio of 9:1) alloy strip into the three-channel quartz tube and seal the tube opening. Connect the radio frequency matching device, place it in the quartz tube with an inner diameter of 4 mm and a wall thickness of 1 mm and seal it. Turn on the mass flow meter and adjust the gas flow rate to 1000 mL / min. Purge the gas for 2 minutes to remove the air in the device. The proportion of H2 in the He / H2 mixture is 2%.

[0063] (2) Turn on the radio frequency power supply and adjust the power to 95W. Radio frequency plasma is generated near the alloy electrode. Quickly reduce the airflow to 100mL / min. After 3 minutes, turn off the power supply. After the device has cooled down sufficiently, remove the electrode and collect the material attached to the inner wall of the quartz tube to obtain gold nanowire powder. The diameter of the nanowire is 50nm~150nm.

[0064] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing metal nanowires, characterized in that, It includes the following steps: S1: Preparation of alloy precursors. The alloy precursors are binary or multi-element alloys, denoted as SM, where S is the element of the obtained nanowires, and M is the alloying element. S is a low-melting-point metal element, and M is an alloying element with a melting point higher than element S. The phase diagram of the alloy precursor SM shows a solid-liquid coexistence region. Element S is selected from Zn, Mg, Sn, Cu, Ag, and Au, and element M is selected from one or more of Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ti, V, Pt, Pd, Ru, Rh, Ir, W, Ta, Ge, and Si. The phase diagram of the alloy precursor SM shows a solid-liquid coexistence region. S2: The alloy precursor is placed as an electrode inside a hollow container with through holes. S3: In step S2, an RF matching device is connected to the portion of the electrode located outside the through-hole of the hollow container. The RF power supply is connected to the RF matching device, and a grounding electrode is surrounded on the outer wall of the hollow container. S4: Protective discharge gas is introduced into the hollow container through another through-hole, and the gas flow rate is controlled. S5: Turn on the radio frequency power supply and apply radio frequency power to the electrodes. Plasma will be generated at the electrodes, and metal nanowires will be obtained on the inner wall of the hollow container. Specifically, by applying a radio frequency voltage to the electrode, a radio frequency plasma with an atmospheric pressure is formed in the protective discharge gas at the electrode. The atmospheric pressure radio frequency plasma forms a high-pressure capacitive sheath on the electrode surface. The high-pressure capacitive sheath causes the electrode surface to heat up to the solid-liquid coexistence region in a short time. The grain boundaries preferentially melt to form microchannels. The high-pressure capacitive sheath has a strong electric field pointing from the plasma region to the electrode surface. The element S melted in the microchannel is charged and is directionally extracted under the action of the electric field. Since there is less metal melted at the grain boundaries and the microchannels are extremely narrow, the extracted metal wires form nanowires and are deposited on the inner wall of the hollow container.

2. The method for preparing metal nanowires as described in claim 1, characterized in that, The hollow container has a through hole at the end. The vacuum container with a through hole at the end is a three-way quartz tube. The alloy precursor, which serves as the electrode, is inserted into one of the through holes of the three-way quartz tube. The second through hole is used as an air inlet, and the third through hole is used as an air outlet. During operation, the air outlet is sealed by liquid.

3. The method for preparing metal nanowires as described in claim 2, characterized in that, The protective discharge gas is a mixture of He and H2 or a mixture of Ar and H2, with the volume ratio of H2 being 1% to 5% in both protective discharge gases.

4. The method for preparing metal nanowires according to any one of claims 1-3, characterized in that, The phase diagram of the alloy precursor contains a solid-liquid coexistence region. The composition of the alloy precursor is Fe-Zn alloy, Fe-Sn alloy, Cu-Zn alloy, Cu-Al alloy, Cu-Sn, Cu-Ti alloy or Cu-Zr alloy.

5. The method for preparing metal nanowires as described in claim 4, characterized in that, The diameter of the metal nanowires ranges from 50 nm to 200 nm.

6. The method for preparing metal nanowires as described in claim 1, characterized in that, The alloy precursor prepared in step S1 is rod-shaped, bar-shaped, sheet-shaped, or strip-shaped to facilitate its use as an electrode and to be easily melted at high temperature in subsequent processes.

7. The method for preparing metal nanowires as described in claim 1, characterized in that, The power applied to the electrodes by the radio frequency power supply through the radio frequency matching device can melt the grain boundaries of the alloy precursor that serves as the electrode, forming a solid-liquid coexistence state.

8. The method for preparing metal nanowires as described in claim 1, characterized in that, Protective discharge gas is used to control plasma temperature, and the flow rate of the protective discharge gas can be adjusted according to the plasma temperature.

9. An apparatus for implementing the preparation method of metal nanowires as described in any one of claims 1-7, characterized in that, It includes an RF matching unit, an RF power supply, a three-way quartz tube, and a grounding electrode. The RF matching unit is connected to an alloy precursor used as an electrode. The alloy precursor is inserted into one through-hole of the three-way quartz tube. A protective discharge gas is introduced into another through-hole of the three-way quartz tube. The third through-hole of the three-way quartz tube is liquid-sealed. The grounding electrode is wrapped around the outer wall of the three-way quartz tube.

10. The apparatus as claimed in claim 9, characterized in that, It also includes a mass flow meter, a gas storage tank, and a water seal device. The protective gas is contained in the gas storage tank. A mass flow meter is installed on the pipeline connecting the gas storage tank and the three-channel quartz tube to monitor the flow rate of the protective discharge gas. The third through hole of the three-channel quartz tube is immersed in the water seal device to be sealed.

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