KR101816800B1 - Method of preparing metal nano wire and 3D metal nano catalyst - Google Patents

Abstract

The present invention relates to a method of manufacturing a metal nanowire and a three-dimensional metal nanocatalyst that does not require a support, comprising the steps of: (A) coating a first polymer substituted with hydroxy on a trench substrate having unevenness formed thereon and then treating it in an oven; (B) coating a block copolymer containing silicon in at least one block on the top surface of the oven treated trench substrate; (C) annealing the trench substrate coated with the block copolymer; (D) ion etching (RIE) the annealed trench substrate to form a pattern and converting the block copolymer to silicon oxide (SiOx); (E) coating the silicon oxide pattern with a second polymer substituted with hydroxy and treating in an oven; (F) coating an acrylic resin on the top surface of the oven-treated silicon oxide pattern; (G) separating the silicon oxide pattern from the coated acrylic resin to form a plurality of engraved patterns in the same shape as the pattern on one side of the acrylic resin; (H) depositing a metal nanowire along a straight column of acrylic resin located between a plurality of intaglio angles; And (I) attaching the metal nanowires of the acrylic resin on which the metal nanowires have been deposited so that the metal nanowires are positioned on the substrate, and then removing the acrylic resin to prepare metal nanowires without a support, It does not have carbon support and minimizes deterioration. Thin thickness reduces the travel distance of material and smooth water discharge.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a metal nano-

The present invention relates to a method of manufacturing a metal nanowire and a three-dimensional metal nanocatalyst which minimizes deterioration due to the absence of a support and which does not require a support, which facilitates reduction of travel distance of the material and discharge of water due to its thin thickness.

One of the major concerns for the commercialization of polymer electrolyte membrane fuel cells is to develop Pt catalysts with better oxygen reduction activity and durability than commercially available Pt / C catalysts.

The present Pt / C catalyst has a problem that the carbon layer supporting the Pt nanoparticles is deteriorated due to the electrochemical oxidation reaction during the operation of the fuel cell, and because of the thick carbon support layer, There is a problem that the cell performance is deteriorated because the diffusion distance required for discharging water is long. In addition, the electrochemical oxidation / corrosion phenomenon of the carbon support layer is a main cause of deterioration of durability of the cell performance.

Recently, several researches on thin film catalyst electrodes having a three-dimensional nanostructure without using a carbon support have been reported in order to fundamentally solve the intrinsic problem of Pt / C catalysts. 3M Company, USA, designed an organic support with a whisker structure with thermal and electrochemical durability, and deposited a thin film electrode on the Pt by sputtering. Since the organic support of the whisker structure does not have conductivity, there is no concern about corrosion, which can solve the degradation problem. However, the manufacturing method is complicated and the effective surface area of Pt itself is very small.

In addition, in the National Institute of Microscale Physics, Hefei, China, nanowires of Pt, carbon core shell structures with Pt nanowires located in the core region were reported. Although a catalyst having excellent deterioration and improved reactivity was produced by producing Pt and carbon core shell nanowires with good crystallinity, a complicated synthesis method was required. Due to problems such as a low yield in the synthesis process and loss of Pt, There is a problem that the manufacturing cost is high.

In addition, at Seoul National University, a polystyrene (PS) sphere was used as a template, electroplating Pt, and then the template was removed to fabricate a three-dimensional Pt structure with an inverse opal structure. This structure is a pure Pt nanostructure with a thickness of 1 to 2 micrometers, which is much thinner than commercial Pt / C catalysts and is free of carbon support. It does not require an ionomer between the catalyst layer and the polymer separator, and is superior in terms of performance and durability Showed excellent results. In this case, however, there is a problem in that the reproducibility of the production process of the PS spherical template is poor for the catalyst production, and there is a problem of the low quality (crystallinity, electrical conductivity, impurities) of the Pt film obtained by the electroplating method.

Accordingly, there is a need for a three-dimensional metal nanocatalyst having no support, excellent in performance and durability, and excellent in reproducibility.

Korean Patent No. 1144109 U.S. Patent No. 8637193 U.S. Patent No. 8557484

It is an object of the present invention to provide a method for producing a metal nanowire that does not require a support.

Another object of the present invention is to provide a metal nanowire that does not require a support manufactured according to the above-described manufacturing method.

It is still another object of the present invention to provide a method for producing a three-dimensional metal nanocatalyst using a metal nanowire that does not require a support.

It is still another object of the present invention to provide a three-dimensional metal nanocatalyst that does not require a support prepared according to the above-described method.

According to another aspect of the present invention, there is provided a method of manufacturing a metal nanowire,

 (A) coating a photolithography-treated trench substrate on which unevenness is formed with a first polymer substituted with a hydroxy;

(B) coating a block copolymer containing silicon in at least one block on the surface of the coated trench substrate;

(C) annealing the trench substrate coated with the block copolymer;

(D) ion etching (RIE) the annealed trench substrate to form a block copolymer pattern and converting the block copolymer present in the pattern into silicon oxide (SiOx);

(E) coating the upper surface of the silicon oxide pattern with a second polymer substituted with hydroxy and treating in an oven;

(F) coating an upper surface of the silicon oxide pattern coated with the hydroxy-substituted second polymer with an acrylic resin;

(G) separating the silicon oxide pattern and the coated acrylic resin to form a plurality of intaglio angles on one surface of the acrylic resin in the same shape as the silicon oxide pattern;

(H) depositing a metal nanowire along a straight column located between a plurality of intaglio angles formed in the acrylic resin; And

(I) attaching a metal nanowire deposited on the acrylic resin to the substrate, and then removing the acrylic resin to produce a metal nanowire having no support.

The hydroxy-substituted first polymer in step (A) may be a PS (polystyrene) brush substituted with hydroxy or a PDMS (polydimethylsiloxane) brush substituted with hydroxy.

In the step (B), the block copolymer may be PS-b-PDMS (polystyrene-b-polydimethylsiloxane) or P4VP-b-PDMS (poly-4-vinylpyridine-b-polydimethylsiloxane).

In the step (C), the annealing may be solvent vapor annealing using toluene.

In the step (C), the annealing may be performed under the condition that the swelling degree of the block copolymer is maintained at 2 to 2.3.

In the step (D), the ion etching may be followed by a CF ₄ plasma process followed by an O ₂ plasma process.

In the step (E), the hydroxy-substituted second polymer may be a PDMS (polydimethylsiloxane) brush substituted with hydroxy.

In the step (F), the acrylic resin may be at least one selected from the group consisting of polymethylmethacrylate (PMMA), methyl acrylate, ethyl acrylate, n-butyl acrylate and t-butyl acrylate.

In step (H), the metal of the metal nanowire may be at least one selected from the group consisting of platinum, gold, silver and rhodium.

In order to achieve the above-mentioned other objects, the metal nanowire of the present invention which does not require a support may be manufactured according to the above-described manufacturing method.

The metal nanowire may have a line width of 20 nm or less.

According to another aspect of the present invention, there is provided a method of manufacturing a three-dimensional metal nano catalyst,

(A) preparing a metal nanostructure by transferring the metal nanowire of claim 11 to a metal foil several times;

(B) coating the acrylic resin on the upper surface of the metal nanostructure, and then removing the metal foil by removing the metal foil;

(C) separating the metal nanostructure coated with the acrylic resin from the metal etchant solution when the metal foil is removed; And

(D) removing the acrylic resin of the metal nanostructure coated with the separated acrylic resin to obtain a metal nanocatalyst.

In the step (a), the metal of the metal foil may be at least one selected from the group consisting of copper, brass, white copper and aluminum.

In the step (b), the metal etchant may be at least one selected from the group consisting of ammonium persulfate, peric chloride and cupric chloride.

In the step (b), the acrylic resin may be at least one selected from the group consisting of polymethylmethacrylate (PMMA), methyl acrylate, ethyl acrylate, n-butyl acrylate and t-butyl acrylate.

According to another aspect of the present invention, there is provided a three-dimensional metal nanocatalyst according to the present invention.

The three-dimensional metal nanocatalyst of the present invention is a three-dimensional metal sphere formed of a metal nanowire. Since it does not have a support such as carbon, it minimizes deterioration and a thin thickness of 20 nm or less reduces the moving distance of the material. This can have a smooth advantage.

In addition, the three-dimensional metal nanocatalyst of the present invention has excellent ORR activity and voltage-current characteristics and excellent reproducibility even without an ionomer.

Such a three-dimensional metal nanocatalyst can be used as a catalyst electrode for an electrochemical reaction of a fuel cell.

1 is a diagram illustrating a process of fabricating a metal nanowire according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a process of fabricating a three-dimensional metal nano-catalyst according to an embodiment of the present invention.
3A and 3C are SEM micrographs of Pt nanocatalysts prepared by stacking Pt nanowires of various layers according to an embodiment of the present invention at an angle of 45 °.
FIG. 3B is a SEM photograph of a section of a three-dimensional Pt nanocatalyst prepared according to an embodiment of the present invention.
FIG. 3D is an SEM photograph of a three-dimensional Pt nano catalyst prepared according to an embodiment of the present invention.
FIG. 4A is a graph showing an ORR characteristic analysis of a three-dimensional Pt nano catalyst according to the number of Pt nanowires laminated according to an embodiment of the present invention and a Pt / C catalyst according to a comparative example.
FIG. 4B is a graph showing the CV curves of the three-dimensional Pt nanocatalyst according to the number of stacked Pt nanowires prepared according to an embodiment of the present invention and the Pt / C catalyst of Comparative Example 1. FIG.
5 is a CV curve graph for analyzing deterioration characteristics of Pt / C catalyst of (a) comparative example and (b) three-dimensional Pt nanocatalyst prepared according to one embodiment.
6 is an ORR curve graph of the number of cycles of (a) the Pt / C catalyst of the comparative example and (b) the three-dimensional Pt nanocatalyst prepared according to one embodiment.

The present invention relates to a method of manufacturing a metal nanowire and a three-dimensional metal nanocatalyst that minimizes deterioration due to the absence of a carbon support, smooths the movement distance of the material due to its thin thickness,

Hereinafter, the present invention will be described in detail.

The present invention relates to a metal nanowire having no support, and a metal nanowire, which is a three-dimensional metal nanostructure, is manufactured using the metal nanowire.

The method of manufacturing a metal nanowire according to the present invention includes the steps of (A) coating a trench substrate having unevenness with a first polymer substituted with hydroxy; (B) coating a block copolymer containing silicon in at least one block on the surface of the coated trench substrate; (C) annealing the trench substrate coated with the block copolymer; (D) ion etching (RIE) the annealed trench substrate to form a block copolymer pattern and converting the block copolymer present in the pattern into silicon oxide (SiOx); (E) coating the upper surface of the silicon oxide pattern with a second polymer substituted with hydroxy; (F) coating an upper surface of the silicon oxide pattern coated with the hydroxy-substituted second polymer with an acrylic resin; (G) separating the silicon oxide pattern and the coated acrylic resin to form a plurality of intaglio angles on one surface of the acrylic resin in the same shape as the silicon oxide pattern; (H) depositing a metal nanowire along a straight column of acrylic resin located between a plurality of intaglio angles formed in the acrylic resin; And (I) attaching the metal nanowires deposited on the acrylic resin to the substrate, and then removing the acrylic resin to prepare a metal nanowire free of supports.

First, in step (A), a hydroxy-substituted first polymer is spin-coated on a trench substrate having irregularities to obtain a defect-free pattern through kinetic improvement of self-assembly, and then the first polymer is spin-coated in an oven at 100 to 160 ° C for 1 to 3 Lt; / RTI >

The trench substrate is preferably a photolithography process to form a circuit, and the irregularities are formed in a width of 0.8 to 2 탆. The irregularities are preferably formed in one direction to control the orientation of the pattern formed of the block copolymer.

The hydroxy-substituted first polymer is a hydroxy-substituted polystyrene (PS) brush or PDMS (polydimethylsiloxane), and is contained in an organic solvent in an amount of 0.5 to 5 wt%, preferably 1 to 2 wt%. When the content of the first polymer is less than the lower limit, the defect concentration can be increased during self-assembly of the block copolymer in the step (C).

Next, in step (B), the first polymer not attached to the oven-treated trench substrate is washed with an organic solvent, and then a block copolymer containing silicon in at least one block is spin-coated on the trench substrate.

The block copolymer in which the silicon is contained in at least one block is a polystyrene-b-polydimethylsiloxane (PS-b-PDMS) or a poly-4-vinylpyridine-b- And it is preferable to use PS-b-PDMS in order to have high durability. Reduced size allows for the production of more thinner metal nanowires, and for high durability, self-assembled patterns of block copolymers can be used permanently when used as a master mold.

The block copolymer is contained in an organic solvent in an amount of 0.5 to 5% by weight, preferably 1 to 2% by weight. When the content of the block copolymer is less than the lower limit, many defects may occur during self-assembly of the block copolymer. If the upper limit value is exceeded, a self-assembly pattern of a multi-layer is obtained instead of a self-assembly pattern of a single layer, which can not be utilized as a master mold.

Next, in the step (C), the trench substrate coated with the block copolymer is annealed at 20 to 25 ° C for 8 to 12 hours.

The annealing may be thermal annealing or solvent vapor annealing. Preferably, the solvent vapor annealing is performed using the vapor of the solvent in consideration of the degree of interblock affinities of the block copolymer, the molecular weight, and the like. In the solvent vapor annealing, the block copolymer is self-assembled into the chamber containing the solvent by the vapor of the solvent after being positioned on the solvent so that the block copolymer is not immersed in the solvent, and toluene is preferable as the solvent.

When performing the solvent vapor annealing, it is preferable that the vapor pressure in the chamber keeps the swelling degree of the block copolymer to 2 to 2.3. When the degree of swelling of the block copolymer is out of the above range, it may be difficult to prepare a self-assembled block copolymer.

Next, in the step (D), the annealed trench substrate is subjected to ion etching (RIE) to form a block copolymer pattern, and the block copolymer existing in the pattern is converted into silicon oxide (SiOx).

The ion etching is performed in two steps. In the first step, the annealed trench substrate is treated with CF ₄ plasma and then treated with O ₂ plasma to convert the block copolymer pattern into a silicon oxide (SiO x) pattern. For example, when PS-b-PDMS is used as the block copolymer, the trench substrate with the self-assembled PS-b-PDMS is treated with CF ₄ plasma to remove the PDMS (removing the PDMS present in the upper portion of the thin film) And then treated with a post-O ₂ plasma to remove the PS and convert the remaining PDMS to silicon oxide (SiO x) in the form of a pattern.

Next, in step (E), the upper surface of the silicon oxide pattern is spin-coated with a second polymer substituted with hydroxy and treated in an oven at 100 to 160 ° C for 1 to 3 hours.

The hydroxy-substituted second polymer has a surface energy lower than that of the self-assembled block copolymer. When the acrylic resin is coated on the polyimide tape after the acrylic resin is separated from the silicon oxide pattern using the polyimide tape in step (G) So that the acrylic resin is transferred and completely separated from the silicon oxide pattern.

The hydroxy-substituted second polymer is a PDMS (polydimethylsiloxane) brush substituted with hydroxy, and is a polymer solution containing 0.5 to 5% by weight, preferably 1 to 2% by weight, in an organic solvent. When the content of the second polymer is less than the lower limit, the silicon oxide pattern and the acrylic resin can not be completely separated.

 Next, in step (F), an acrylic resin is spin-coated on the upper surface of the silicon oxide pattern spin-coated with the hydroxy-substituted second polymer.

The second polymer that has not reacted with the trench substrate may be removed with a heptane solvent before spin coating with the acrylic resin.

The acrylic resin may be at least one selected from the group consisting of polymethylmethacrylate (PMMA), methyl acrylate, ethyl acrylate, n-butyl acrylate, and t-butyl acrylate. Is preferably used.

The acrylic resin is contained in a solvent composed of acetone, toluene and heptane in a weight ratio of 3.0-4.5: 3.0-4.5: 1.0-4.0 in an amount of 1 to 10% by weight, preferably 1 to 3% by weight. If the solvent in which the acrylic resin is dissolved does not have any one of the above three solvents or another solvent, spin coating of the acrylic resin may not be performed properly. When the content of the acrylic resin is less than the lower limit, it may be difficult to form a pattern in the shape of the pattern in the step (G). If the content exceeds the upper limit, it may be difficult to remove the acrylic resin in the step (I) have.

Next, in step (G), the silicon oxide pattern and the acrylic resin coated on the upper surface of the silicon oxide pattern are separated to form a plurality of recesses in the same shape as the silicon oxide pattern on one side of the acrylic resin.

Specifically, when the polyimide tape is attached to the upper surface of the acrylic resin coated with the silicon oxide pattern and then the tape is pulled as if the tape is peeled off, the acrylic resin is transferred to the polyimide tape side so that the silicon oxide pattern and the acrylic resin coated therewith are separated do. The thus-separated acrylic resin has a pattern having the same shape as that of the silicon oxide pattern formed on the side of the silicon oxide pattern side.

Next, in step (H), a metal nanowire is deposited along a straight line located between a plurality of embossing angles formed on the acrylic resin.

The surface of the acrylic resin on which the engraved pattern is formed is positioned so as to be inclined at 30 to 45 degrees with respect to the direction in which the metal is deposited, and the metal is deposited along a straight line between the plurality of engraved angles. The metal deposited along the straight line is called a metal nanowire.

The rate at which the metal is deposited is 0.1 to 0.5 A / S, preferably 0.2 to 0.3 A / S. When the deposition rate exceeds the upper limit value, the thickness of the metal nanowires may not be constant.

In addition, it is preferable that the thickness to which the metal is deposited is a thickness that does not cover the concavity and convexity of the acrylic resin. When the metal covers the concavities and convexities of the acrylic resin, it is simply transferred to the metal thin film at the time of final transfer, and is not transferred to the metal nanowire.

The deposited metal may be at least one selected from the group consisting of platinum, gold, silver and rhodium.

Next, in the step (I), the metal nanowires deposited on the acrylic resin are attached to the substrate, and then the acrylic resin is removed to prepare metal nanowires free of supports.

Specifically, in order to weaken the adhesion between the polyamide tape and the acrylic resin, an acrylic resin on which metal nanowires have been deposited is attached to PDMS immersed in an organic solvent for 8 to 10 hours for 8 to 15 seconds The metal nanowires deposited on the acrylic resin are adhered to the substrate and the polyimide film is removed to transfer only the metal nanowire and the acrylic resin deposited on the substrate. Thereafter, only the acrylic resin is removed to obtain only metallic nanowires.

The substrate is not particularly limited as long as it is a substrate that can be easily separated from metal nanowires. The organic solvent used in the production of the metal nanowires is not particularly limited, but toluene is preferably used.

The metal nanowires produced according to this method can be manufactured to be very thin, with a line width of 20 nm or less, preferably 1 to 20 nm.

In addition, the present invention can produce a three-dimensional metal nanocatalyst using the metal nanowire.

The method for producing the three-dimensional metal nanocatalyst according to the present invention comprises the steps of: (a) preparing a metal nanostructure by transferring the metal nanowire to a metal foil several times; (B) coating an upper surface of the metal nanostructure with an acrylic resin and then removing the metal foil; (C) separating the metal nanostructure coated with the acrylic resin from the metal etchant solution when the metal foil is removed; And (d) removing the acrylic resin of the metal nanostructure coated with the separated acrylic resin to obtain a metal nanocatalyst.

First, in the step (a), the metal nanowires prepared above are transferred several times to a metal foil to produce a three-dimensional metal nanostructure.

The metal nanowire may be stacked by a desired number of layers to provide a three-dimensional metal nanostructure.

After the 3-dimensional metal nanostructure is prepared, RTA is annealed at 500 to 700 ° C for 5 to 20 minutes under an Ar atmosphere to remove the polymer that has not been removed in the metal nanowire process.

The metal is not particularly limited as long as the metal can be easily removed from the metal foil. Preferably, the metal foil is at least one selected from the group consisting of copper, brass, white copper and aluminum.

Next, in step (b), an acrylic resin is coated on the upper surface of the three-dimensional metal nanostructure, and then the metal foil is removed by removing the metal foil.

The acrylic resin is used for protecting the three-dimensional metal nanostructure from the external environment when the metal foil is removed. Specifically, the acrylic resin is preferably a copolymer of PMMA (polymethylmethacrylate), methyl acrylate, ethyl acrylate, n-butyl acrylate and t- And at least one selected from the group consisting of

The acrylic resin may be contained in a solvent composed of acetone, toluene and heptane in a weight ratio of 3.0-4.5: 3.0-4.5: 1.0-4.0 in an amount of 1 to 10% by weight, preferably 1 to 3% by weight.

The metal etchant is not particularly limited as long as it is a wet etchant capable of removing the metal foil, and preferably at least one selected from the group consisting of ammonium persulfate, peric chloride and cupric chloride.

Next, in the step (c), when the metal foil is removed, the three-dimensional metal nanostructure coated with the acrylic resin is separated from the metal etchant aqueous solution.

At this time, a substrate can be used to facilitate separation of the three-dimensional metal nanostructure coated with the acrylic resin.

The type of the substrate is not particularly limited as long as it is a substrate stable to a metal etchant solution. Preferably, the substrate is at least one selected from the group consisting of RDE, a membrane, and a gas diffusion layer.

Next, in step (d), the acrylic resin of the metal nanostructure coated with the separated acrylic resin is removed to obtain a three-dimensional metal nanocatalyst, which is a metal nanostructure.

The three-dimensional metal nanocatalyst prepared according to the above method has no carbon support, minimizes deterioration, and has a thin thickness to reduce the moving distance of the material and smooth the discharge of water.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

matter

Hydroxy-treated PS (38 kg / mol) to be used as a brush, hydroxy-treated PDMS (5 kg / mol) as a block copolymer (PS-b-PDMS 48 kg / mol, PS = 31 kg / mol PDMS = kg / mol) were purchased from Polymer source, Canada.

PMMA (100 kg / mol) and ammonium persulfate were also purchased from Sigma Aldrich.

Example 1. Three-dimensional Pt nanocatalyst - no support

Manufacture of Pt Nanowires

A trench substrate having a width of 1 μm and a depth of 40 nm was treated by a photolithography process, spin-coated with a toluene solution containing 1.5% by weight of hydroxy-treated PS brush (38 kg / mol) Put in a vacuum oven for 2 hours to perform PS brushing on the trench substrate. Thereafter, the PS polymer was rinsed with a toluene solution to remove PS polymer not attached to the trench substrate, and then a toluene solution containing 1 wt% of PS-b-PDMS of 48 kg / mol was spin-coated on the trench substrate. -Provide the trench substrate coated with PDMS at room temperature with solvent solution annealing (solvent vapor annealing) for about 10 hours. The degree of vapor pressure in the chamber during annealing allows the swelling ratio (swollen ratio / initial thickness) of PS-b-PDMS to be maintained around 2 to 2.3.

(50w / 10w 20 sec) in order to remove the thin film PDMS provided on the annealed substrate. Secondly, O ₂ plasma (60w / 10w 30 sec.

Thereafter, the upper surface of the silicon oxide pattern was spin-coated with a hydroxy-treated PDMS brush to lower the surface energy of the silicon oxide pattern, and a chemical treatment was carried out by heating at 150 ° C for 2 hours in a vacuum oven.

After the heat treatment, the remaining PDMS polymer that did not react with the trench substrate was removed with a heptane solvent. Then, PMMA (100 kg / mol, 2 wt%, solvent acetone: toluene: heptane = 4.5: 4.5: 1) Spin coat the solution. When a polyimide tape having an adhesive force is attached to the upper surface of the PMMA and then peeled off, the same shape as the pattern is formed on the PMMA in a reverse phase structure.

When the PMMA was deposited at an appropriate slope (30 ° to 45 °) relative to the Pt deposition direction (deposition rate = 0.2 / S), the PMMA thin film was subjected to a Pt nanowire along the concavities and the convexities And is deposited. Then, in order to weaken the adhesion between the polyimide tape and the PMMA, it was adhered to the PDMS immersed in the toluene solution for about 10 hours for 10 seconds, then peeled off, reattached to the substrate, and the polyimide tape was peeled off, Is transferred to the substrate and only the polyimide tape can be easily peeled off. Thereafter, only PMMA was washed away with acetone to finally obtain a Pt nanowire having a line width of 20 nm.

Manufacture of three-dimensional Pt nanocatalyst

The Pt nanowire obtained by the above method was transferred to copper foil several times to produce a three-dimensional Pt nanostructure. In order to remove the residual polymer that was not completely removed during the Pt nanowire fabrication process, Heat treatment is carried out for 10 minutes.

After the heat treatment, PMMA (same as PMMA) was spin-coated on the Pt nanostructure for the final transfer process, and then the copper foil was selectively removed by floating in a copper etchant solution such as ammonium persulfate (0.1M) Separate the 3-dimensional Pt nanostructure coated with PMMA with a membrane substrate and rinse the remaining enough with DI water. Thereafter, PMMA was removed with acetone to finally obtain a three-dimensional Pt nanocatalyst.

Comparative Example 1. Pt / C catalyst (Pt 20% by weight)

0.05 g of carbon black (carbon support) was mixed with 100 mL of ethylene glycol solvent and dispersed using ultrasonic wave for 20 minutes. On the other hand, 0.0332 g of H ₂ PtCl ₆ .6H ₂ O was dissolved in 10 mL of ethylene glycol and dispersed using ultrasonic waves for 5 minutes.

The carbon support solution and the Pt precursor solution were mixed and stirred for 30 minutes, the pH of the suspension was adjusted to 12, and the mixture was heated at 160 ° C for 3 hours for reduction, followed by stirring at room temperature for 12 hours. After completion of the reaction, the pH of the obtained precipitate was adjusted to 3, the precipitate was washed with deionized water to remove all impurities, dried at 40 ° C in a vacuum oven for 24 hours, and finally heat treated at 160 ° C or higher to prepare a Pt / C catalyst Respectively.

<Test Example>

Test Example 1. SEM measurement

3A and 3C are SEM photographs of Pt nano catalysts prepared by stacking Pt nanowires prepared according to Example 1 of the present invention at an angle of 45 DEG. FIG. 3B is a cross-sectional view of the Pt nanocatalyst And FIG. 3D is a SEM photograph of the Pt nanocatalyst taken on an enlarged scale.

The Pt nanocatalyst photographed by the SEM is a catalyst in which 40 layers of Pt nanowires are rotated by 45 ° when the Pt nanowires are transferred one layer at a time.

As shown in FIGS. 3A to 3D, it was confirmed that the Pt nanocatalyst was composed of only Pt nanowire to form a three-dimensional structure, and when the Pt nanowire was laminated to 40 layers, it was confirmed that the thickness of the Pt nanocatalyst was 400 nm Respectively.

The Pt nanocatalyst of the present invention can be prepared as a catalyst having a desired thickness by controlling the number of stacked Pt nanowires.

Pt nano-catalyst CV  And ORR How to measure

Cyclic voltammetry (CV) and Oxygen reduction reaction (ORR) curves were measured to investigate the electrochemical properties of Pt nanocatalysts.

Potentiostat equipment was used to carry out the experiment and 100 mL of 0.1M HClO ₄ was directly applied to the electrolyte solution. A reference electrode used as a reference electrode was an Ag / AgCl electrode, and a counter electrode was a Pt wire. In correspondence thereto, the Pt nano catalyst prepared according to Example 1 was used as a glassy carbon (0.196 cm ²⁾ The Pt electrode was fabricated as a working electrode of a half cell test to confirm the electrochemical characteristics of the RDE electrode. The characteristics of the Pt nanostructure were confirmed.

In order to carry out the cyclic voltammetry (CV) experiment, a half cell test was prepared as described above, and the voltage of the working electrode (WE) was stabilized at a flow rate of 400 ml / min Gas purging is carried out for 1 minute. The circulation voltage is applied from 0.05 V to 1.1 V at a speed of 20 mV / s to the purged experimental apparatus, and the CV experiment is conducted 10 times in total.

Oxygen Reduction Reaction (ORR) measurement is performed at a flow rate of 400 ml / min to make an environment in which the working electrode (WE) reacts with oxygen in the electrolyte. The experiment is performed after the voltage of the working electrode WE is stabilized in the same manner as in the CV experiment described above, and the purging time is 30 minutes or more. After gas purging is complete, measure ORR twice at a rate of 5 mV / s from 0.05 V to 1.1 V.

Test Example  2. CV  And ORR  Measure

FIG. 4A is a graph showing the ORR characteristics of the three-dimensional Pt nanocatalyst according to the number of Pt nanowires laminated according to Example 1 of the present invention and the Pt / C catalyst of Comparative Example 1. FIG. 3 is a graph showing the CV curves of the three-dimensional Pt nanocatalyst according to the number of stacked Pt nanowires prepared according to Example 1 and the Pt / C catalyst of Comparative Example 1. FIG.

FIG. 4A is a value obtained in the second measurement in the ORR measurement described above, and FIG. 4B is a value obtained in the 10th measurement in the CV measurement described above.

As shown in FIG. 4A, the ORN characteristics of the three-dimensional Pt nanocatalyst in which Pt nanowires were laminated in 40 layers had a limiting current and a half wave potential value close to that of the Pt / C catalyst of Comparative Example 1 Respectively.

Also, the active area of the catalyst can be calculated through the adsorption and desorption amount of hydrogen by the CV curve. As shown in FIG. 4B, the Pt nanowire having 20 layers, 30 layers and 40 layers It was confirmed that the active area had a value similar to that of Pt / C in Comparative Example 1.

5 is a CV curve graph for analyzing deterioration characteristics of a Pt / C catalyst of (a) Comparative Example 1 and (b) a three-dimensional Pt nanocatalyst prepared by stacking 40 layers of Pt nanowires prepared according to Example 1. FIG.

As shown in FIG. 5, unlike the Pt / C catalyst of Comparative Example 1, the three-dimensional Pt nanocatalyst of Example 1 had no carbon support and thus showed much better durability after 6000 cycles.

6 is an ORR curve graph of the number of cycles of (a) Pt / C catalyst of Comparative Example 1 and (b) three-dimensional Pt nanocatalyst prepared by stacking 40 layers of Pt nanowires prepared according to Example 1. FIG.

As shown in FIG. 6, it was confirmed that the Pt / C catalyst of Comparative Example 1 gradually decreased in activity characteristics of the catalyst as the cycle number increased, whereas the three-dimensional Pt nano catalyst without the carbon support had a cycle number But the activity of the enzyme was decreased by a relatively small amount.

Claims (17)

(A) coating a photolithography-treated trench substrate on which unevenness is formed with a first polymer substituted with a hydroxy;
(B) coating a block copolymer containing silicon in at least one block on the surface of the coated trench substrate;
(C) annealing the trench substrate coated with the block copolymer;
(D) ion etching (RIE) the annealed trench substrate to form a block copolymer pattern and converting the block copolymer present in the pattern into silicon oxide (SiOx);
(E) coating the upper surface of the silicon oxide pattern with a second polymer substituted with hydroxy and treating in an oven;
(F) coating an upper surface of the silicon oxide pattern coated with the hydroxy-substituted second polymer with an acrylic resin;
(G) separating the silicon oxide pattern and the coated acrylic resin to form a plurality of intaglio angles on one surface of the acrylic resin in the same shape as the silicon oxide pattern;
(H) depositing a metal nanowire along a straight column located between a plurality of intaglio angles formed in the acrylic resin; And
(I) attaching a metal nanowire deposited on the acrylic resin to a substrate, and then removing the acrylic resin to prepare a metal nanowire without a support. . The method of claim 1, wherein the hydroxy-substituted first polymer in step (A) is hydroxy-substituted polystyrene (PS) or hydroxy-substituted polydimethylsiloxane (PDMS) Method of manufacturing nanowire. The method of claim 1, wherein the block copolymer in step (B) is poly-4-vinylpyridine-b-polydimethylsiloxane (PS-b-PDMS) or P4VP-b- A method for producing a metal nanowire that does not require a support. The method according to claim 1, wherein the annealing in the step (C) is solvent vapor annealing using toluene. The method according to claim 1, wherein the degree of swelling of the block copolymer during annealing in the step (C) is maintained at 2 to 2.3. The method according to claim 1, wherein the ion etching in the step (D) is a CF ₄ plasma treatment followed by an O ₂ plasma treatment. The method according to claim 1, wherein the second polymer substituted with hydroxy in step (E) is a PDMS (polydimethylsiloxane) brush substituted with hydroxy. The method of claim 1, wherein the acrylic resin in step (F) is at least one selected from the group consisting of polymethylmethacrylate (PMMA), methyl acrylate, ethyl acrylate, n-butyl acrylate, and t- Wherein a support is not required. The method according to claim 1, wherein the acrylic resin is contained in a solvent composed of acetone, toluene and heptane in an amount of 1 to 10% by weight in the step (F). The method according to claim 1, wherein the metal of the metal nanowire in step (H) is at least one selected from the group consisting of platinum, gold, silver and rhodium. delete delete (A) preparing a metal nanostructure by transferring the metal nanowire produced according to the manufacturing method of any one of claims 1 to 10 several times to a metal foil;
(B) coating the acrylic resin on the upper surface of the metal nanostructure and removing the metal foil; and removing the metal foil by immersing only the metal foil in the metal etchant solution to remove the metal foil;
(C) separating the metal nanostructure coated with the acrylic resin from the metal etchant solution when the metal foil is removed; And
(D) removing the acrylic resin of the metal nanostructure coated with the separated acrylic resin to obtain a metal nanocatalyst. 14. The method of claim 13, wherein the metal of the metal foil in step (a) is at least one selected from the group consisting of copper, brass, white copper, and aluminum. 14. The method according to claim 13, wherein the metal etchant in step (b) is at least one selected from the group consisting of ammonium persulfate, peric chloride, and cupric chloride. . [14] The method of claim 13, wherein the acrylic resin is at least one selected from the group consisting of polymethylmethacrylate (PMMA), methyl acrylate, ethyl acrylate, n-butyl acrylate, and t- Wherein the support is not required. delete

Images