CN115846673A - Method for efficiently preparing one-dimensional metal nanowires - Google Patents

Abstract

The invention discloses a method for efficiently preparing a one-dimensional metal nanowire. The method is characterized in that surface modification is carried out on a mold with a surface micro-nano structure, and then metal is pressed into a cavity of the mold subjected to the surface modification under the conditions of certain pressure and temperature so as to copy a micro-nano structure pattern in the mold. The invention has the advantages that after the surface modification treatment is carried out on the mold, the sliding potential barrier of the metal on the surface of the cavity of the mold is reduced, so that the growth rate of the metal in the mold after the surface modification treatment is obviously improved compared with the growth rate in the mold without the surface modification treatment under the same molding condition. More importantly, the method has remarkable effect on most of metals, metallic glass and polymers.

Description

Method for efficiently preparing one-dimensional metal nanowires

Technical Field

The invention relates to the technical field of nano manufacturing, in particular to a method for efficiently preparing a one-dimensional nanowire.

Background

Nanostructures play a crucial role in a wide variety of fields (see the article entitled "Nanofabrication through molding" published in Progress in Materials Science at 4 months 2022 for details). For example, silver nanostructures are widely used for surface enhanced raman spectroscopy, and copper nanostructures have significant catalytic efficiency. Particularly, metal nanowires with high aspect ratios are basic raw materials in applications such as flexible electronic devices, conductive inks, and the like. At present, methods for preparing one-dimensional nanowires mainly include chemical growth, photolithography, self-assembly process, scanning probe-based Dip pen technology (see the paper entitled "Dip-pen" nanolithography in Science published in 1 month 1999), and the like. These methods allow the fabrication of uniform metal nanopatterns, but are costly due to time-consuming, multi-step processes, and are also limited in the preparation of nanostructures with high aspect ratios.

In 2017, the Liu Ze topic group of Wuhan university developed a nano die casting technology based on plastic deformation (see the paper published in Nature Communications in 3 months of 2017 entitled "One-step polymerization of crystalline metallic nano-imprinting with low porous casting" and the invention patent in patent number CN107572476B entitled "method for preparing metal micro-nano structure"), and the method is in principle suitable for rapid manufacturing of various metal nano-structures. However, since interfacial friction is a surface force, the effect is prominent as the feature size decreases, and thus the flow resistance of the metal in the nanopore cavity will increase significantly as the size of the pore decreases. Although the molding efficiency can be improved by superimposing the micro-vibrations in the molding pressure (see the article published in Materials Letters of "Observation of speed growth of metal nanodevices by-low frequency micro-simulation" at 1 month 2021 and the article published in Nature Communications in China Letters of Rapid simulation of compact construction using a micro-mechanical simulation ") at 5 months 2021), the improvement in the efficiency is limited. In order to rapidly prepare the metal nanowire with a large length-diameter ratio, the most effective method is to increase the temperature or the molding pressure of the nano die casting, but the increase of the temperature increases the energy consumption, and the increase of the molding pressure is limited by the strength of the mold. Therefore, finding methods and developing processes to improve the manufacturing efficiency of metal nanostructures is a challenge to be solved urgently.

Disclosure of Invention

The invention aims to provide a method for realizing the efficient preparation of one-dimensional metal nanowires. The invention reduces the sliding potential barrier of metal on the surface of the nano-mold cavity by modifying the surface of the nano-mold, realizes the boundary sliding of the metal in the nano-cavity, and greatly improves the preparation efficiency of the one-dimensional nano-wire.

The technical scheme provided by the invention is as follows:

a method for efficiently preparing a one-dimensional metal nanowire comprises the following steps:

(1) Carrying out surface modification treatment on the die with the one-dimensional micron or nanometer pore canal;

(2) Stacking a material to be molded and a mold with a modified surface on a heated platen;

(3) Applying load to press the material to be die-cast into the die to obtain a composite structure of the material to be die-cast and the die;

(4) And removing the mold to obtain the die casting material with the surface copied with the nanowire structure.

Further, the surface modification treatment method is to deposit a layer of coating on the surface of the mould through chemical vapor deposition or physical vapor deposition.

Still further, the thickness of the coating is from a monoatomic layer to several tens of nanometers.

Still further, the coating includes a polymer coating, a carbon material, a metal, and a ceramic layer.

Further, the polymer coating includes fluorosilane and octadecyltrichlorosilane.

Further, the material to be die-cast is a metal simple substance or an alloy with the melting point temperature lower than 1800 ℃ in the atmospheric environment.

Furthermore, the material to be die-cast is a metal simple substance or an alloy with the melting point temperature lower than 1200 ℃ in the atmospheric environment.

Further, the die material is a material which has a higher melting point and higher hardness than the material to be die-cast.

Still further, the mold material includes metal, silicon nitride, silicon oxide, and aluminum oxide.

Further, the load application speed is 1-1000N/s, the peak load is 0.1-50kN, and the load unloading speed is 0.001-5kN/s.

The principle of the invention is as follows: as shown in fig. 1, when the surface of the mold is modified to reduce the sliding barrier of the metal on the surface of the mold, the velocity of the metal at the interface of the mold may not be zero during the molding process (the sliding length b is used to represent this effect in the right diagram of fig. 1). For viscous fluids such as metallic glass, the velocity profile during die casting is shown in the right diagram of FIG. 1, where v _z For the flow rate of the viscous fluid in the pipe, obviously, the flow rate is the largest at the center of the pipe, and compared with the case that the metal-mold interface is sticky and does not slip, under the same condition, when the slip exists at the interface, the length of the prepared metal nanowire is larger:

in the above formula, R is the radius of the nano-pore cavity, L ₁ And L ₂ The lengths of nanowires obtained after die casting using untreated and surface-modified nano dies, respectively. For crystalline metals, a similar effect will be exhibited when the die casting temperature is in the diffusion dominated temperature range.

The invention has the following beneficial effects:

the method reduces the sliding potential barrier of the metal on the surface of the cavity of the mold through the surface modification treatment of the mold, so that the growth rate of the metal in the mold after the surface modification treatment is obviously improved compared with the growth rate in the mold without the treatment under the same molding condition. The invention can improve the forming efficiency of metal by two orders of magnitude by a surface modification method, which is far larger than the reported technology. In addition, the invention is also applicable to materials such as high molecules, metal glass and the like, and has wide application prospect in the micro-nano processing field.

Drawings

Fig. 1 is a schematic view showing hot embossing of a combination of a mold having a surface modified and a material to be molded.

In the figure: 1. a hot-pressing plate; 2. a material to be molded; 3. a surface modified mold; 4. the modification layer is arranged on the surface of the cavity of the mold.

Fig. 2 is an optical microscope photograph of the surface of a sample after molding a metallic glass (left is the surface of a sample after molding using an untreated mold, and right is the surface of a sample after molding using an Octadecyltrichlorosilane (OTS) -treated mold).

FIG. 3 is a Scanning Electron Microscope (SEM) cross-sectional view of a sample after metallic glass was die-cast at 265 deg.C (left is a sample after die-casting using an untreated die, and right is a sample after die-casting using an OTS-treated die).

FIG. 4 shows 0.68T _m (T _m Absolute temperature scale, same below) temperature of the die cast bismuth (left is a sample after die casting using an untreated die, right is a sample after die casting using an OTS treated die).

FIG. 5 is 0.87T _m SEM images of the cross-section of bismuth after die casting at temperature (left for samples after die casting using untreated die, right for samples after die casting using OTS treated die).

FIG. 6 shows 0.67T _m SEM images of cross-section after die casting of metallic silver at temperature (left is a sample after die casting using an untreated die, and right is a sample after die casting using a die in which carbon is deposited on the surface by chemical vapor deposition).

FIG. 7 shows a comparison of die casting of various metals using AAO molds with unmodified and modified surfaces under otherwise identical conditions (0.6T) _m And 300 MPa), the length of the prepared nanowire is obviously improved by using the modified AAO die.

Detailed Description

The invention will be further described with reference to the accompanying drawings in which:

in order to illustrate the invention more clearly, the following examples are provided:

example 1

The metal glass nano-wire is prepared efficiently. Firstly, smelting suction-cast platinum-based metallic glass (Pt) from a copper mould _57.5 Cu _14.7 Ni _5.3 P _22.5 Hereinafter referred to as Pt-BMG) were cut out into pieces of platinum of similar weight (0.05 g) and then thermoplastically shaped at 250 c, with maximum applied load and shaping time of 6kN and 30s, respectively, to give thin discs of similar area size. The surface oxide layer was then removed using 4000 mesh sandpaper abrasion and the sample was rinsed with ethanol and deionized water. Placing an Anodic Aluminum Oxide (AAO) template in an Octadecyl Trichlorosilane (OTS) environment for heat preservation treatment for 2h at 100 ℃. The Pt-BMG/AAO template combinations with and without OTS treatment were die cast under identical conditions (FIG. 1), at a forming temperature of 265 ℃ and a forming load of 100N/s loaded to 5kN followed by rapid unloading (5 kN/s). The optical photograph of the surface of the molded sample is shown in FIG. 2. The sample was cut and the length of the Pt-BMG nanowire in the central region thereof was measured as shown in fig. 3. The length of Pt-BMG nanowires prepared under the same conditions was increased by about 3 times using the OTS surface-modified AAO mold compared to the untreated AAO mold (fig. 3).

Example 2

Preparing the metal nanowire by nano die casting at a lower temperature. First a bismuth block of approximately the same weight (0.07 g) was cut out of the same parent material and then pre-pressed at 200 ℃ to obtain a bismuth sheet of approximately round piece, the pre-pressing load being increased from 0 to 1.5kN at a loading rate of 100N/s and then rapidly unloaded (5 kN/s). The surface oxide layer was then removed using 4000 mesh sandpaper abrasion and the sample was rinsed with ethanol and deionized water. And (3) placing the AAO template in an OTS environment for heat preservation treatment at 100 ℃ for 2h. Finally, the Bi/AAO template combination without and with OTS treatment was nano-cast at 100 deg.C (FIG. 1) with a forming load of 0 to 3kN and then rapidly unloaded (5 kN/s) at a loading rate of 100N/s. The length of the nanowires in the central area of the molded sample was measured, as shown in fig. 4, the left graph of fig. 4 is the nanowires after molding using an untreated AAO template, and the right graph is the nanowires after molding using an OTS treated AAO template. Clearly, the length of the nanowires after molding was increased by nearly 1 order of magnitude compared to using untreated molds, using OTS treated molds (fig. 4).

Example 3

Preparing the metal nano-wire at high temperature. First, a bismuth block having approximately the same weight (0.07 g) was cut out from the same parent material, and then pre-pressed at 200 ℃ to obtain approximately circular bismuth flakes, with a pre-pressing load of increasing from 0 to 1.5kN at a loading rate of 100N/s and then rapidly unloaded (5 kN/s). The surface oxide layer was then removed using 4000 mesh sandpaper abrasion and the sample was rinsed with ethanol and deionized water. And (3) placing the AAO template in an OTS environment for heat preservation treatment at 100 ℃ for 2h. Finally, the Bi/AAO template combination without and with OTS treatment was die-cast at 200 deg.C (FIG. 1) with die-casting loads from 0 to 3KN at a loading rate of 100N/s and then unloaded quickly (5 kN/s). The length of the nanowires in the central area of the molded sample was measured, as shown in fig. 5, the left graph of fig. 5 is the nanowires after molding using the untreated AAO template, and the right graph is the nanowires after molding using the OTS treated AAO template. Clearly, the length of the nanowires after molding is increased by nearly 2 orders of magnitude compared to using untreated molds, using OTS treated molds.

Example 4

Carbon is used as a modification layer. Silver blocks of approximately the same weight (0.015 g) were first cut from the same parent material and then pre-pressed at 400 ℃ to obtain approximately round sheets, the pre-pressing load being increased from 0 to 3kN at a loading rate of 100N/s and then rapidly unloaded (5 kN/s). The surface oxide layer was then removed using 4000 mesh sandpaper abrasion and the sample was rinsed with ethanol and deionized water. Depositing a layer of carbon material on the surface of the AAO pore channel by using a Chemical Vapor Deposition (CVD) method at any temperature in the temperature range of 450-650 ℃. The AAO/Ag template combination without and with carbon deposition was die cast at 550 deg.C (FIG. 1) with a die cast load of 0 to 4KN and quick unload (5 kN/s) at a loading rate of 100N/s. The length of nanowires in the central region of the molded sample was measured, and as shown in fig. 6, the nanowires were molded using an untreated AAO template in the left side of fig. 6, and nanowires were molded using an AAO template with CVD deposited carbon material in the right side. Clearly, the length of the nanowires after molding was increased several times compared to the mold using the untreated mold, which deposited the carbon material by CVD (fig. 6).

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention.

Claims (10)

1. A method for efficiently preparing a one-dimensional metal nanowire is characterized by comprising the following steps:

(1) Carrying out surface modification treatment on the die with the one-dimensional micron or nanometer pore canal;

(2) Stacking the material to be molded and the mold with the modified surface on a heated pressing plate;

(3) Applying load to press the material to be die-cast into the die to obtain a composite structure of the material to be die-cast and the die;

(4) And removing the mold to obtain the die casting material with the surface copied with the nanowire structure.

2. The method of claim 1, wherein: the surface modification treatment method is to deposit a layer of coating on the surface of the mould through chemical vapor deposition or physical vapor deposition.

3. The method of claim 2, wherein: the thickness of the coating is from a single atomic layer to tens of nanometers.

4. The method of claim 2, wherein: the coating comprises a polymer coating, a carbon material, a metal and a ceramic layer.

5. The method of claim 2, wherein: the polymer coating comprises fluorosilane and octadecyltrichlorosilane.

6. The method of claim 1, wherein: the material to be die-cast is a metal simple substance or alloy with the melting point temperature lower than 1800 ℃ in the atmospheric environment.

7. The method of claim 6, wherein: the material to be die-cast is a metal simple substance or an alloy with the melting point temperature lower than 1200 ℃ in the atmospheric environment.

8. The method of claim 1, wherein: the die material is a material with higher melting point and higher hardness than the material to be die-cast.

9. The method of claim 8, wherein: the mold material includes metal, silicon nitride, silicon oxide, and aluminum oxide.

10. The method of claim 1, wherein: the load application speed is 1-1000N/s, the peak load is 0.1-50kN, and the load unloading speed is 0.001-5kN/s.

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