KR101854736B1 - Catalyst and method of producing catalyst - Google Patents

Abstract

The present invention relates to a catalyst and to a method for producing a catalyst, wherein the method for producing a catalyst comprises the following steps: (a) producing transition metal oxide nanoparticles (100); and (b) laminating a plurality of layers (20) comprising the transition metal oxide nanoparticles (100) on a conductive substrate (10). According to one embodiment of the present invention, it is possible to utilize the catalyst which can be used for various chemical reactions for producing high stability and chlorine, has high catalytic efficiency, and has an economical effect.

Description

[0001] CATALYST AND METHOD OF PRODUCING CATALYST [0002]

The present invention relates to a catalyst and a catalyst preparation method. More particularly, the present invention relates to a catalyst capable of promoting a chlorine oxidation reaction using a transition metal oxide and a method for producing the catalyst.

Chlorine is used as a core raw material in various fields such as plastics, chemical materials, pulp production and water disinfection, and it is a chemical raw material with huge market scale around the world. In particular, ship ballast water treatment equipment is essential to prevent marine ecosystem destruction and disturbance due to the movement of ballast water. Due to the international demand and interest pursuant to the Convention on Ballast Water Management, multi - billion - dollar vessels As the ballast water treatment market is expected to be newly formed, the importance of chlorine production is emerging as the ballast water treatment system using chlorine is expected to lead the global ship equilibrium water treatment market.

Currently, industry produces chlorine electrochemically by oxidizing brine. Since the chlorine oxidation reaction is in competition with the oxygen evolution reaction (Oxygen evolution reaction), it is necessary to develop a catalyst that suppresses the oxygen generation reaction and promotes the chlorine oxidation reaction for efficient and stable chlorine production .

As a catalyst promoting the chlorine oxidation reaction, currently industrial noble metal-based catalysts such as Ru, Pt and Ir are used. Precious metal based oxide catalysts for chlorine oxidation catalysis show good properties but are expensive due to scarcity. Therefore, in order to compete for price and to preoccupy the market, it is necessary to develop a chlorine oxidation catalyst manufactured using relatively inexpensive raw materials.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a catalyst and a catalyst production method which have high stability and can be utilized for various chemical reactions to produce chlorine, .

However, these problems are exemplary and do not limit the scope of the present invention.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: (a) preparing transition metal oxide nanoparticles; And (b) laminating a plurality of layers composed of said transition metal oxide nanoparticles on a conductive substrate.

According to an embodiment of the present invention, the step (a) includes the steps of: (a1) preparing a first solution containing a transition metal ion supplying material and a fatty acid surfactant; (a2) preparing a second solution comprising an alcohol surfactant; (a3) aging the first solution and the second solution at a predetermined temperature; (a4) introducing the second solution into the first solution to prepare the transition metal oxide nanoparticles; (a5) aging the transition metal oxide nanoparticles at a predetermined temperature; And (a6) surface-treating the transition metal oxide nanoparticles.

According to an embodiment of the present invention, the step (b) includes the steps of: (b1) preparing a catalyst mixture by mixing the transition metal oxide nanoparticles with a carbon additive and a polymeric binder; (b2) preparing a third solution in which the catalyst mixture is dispersed in an organic solvent; And (b3) applying the third solution onto the conductive substrate.

According to an embodiment of the present invention, the carbon additive may be at least one selected from the group consisting of Graphene, Carbon Nanotube, Carbon Fiber, Artificial Graphite, Carbon Black, , Activated carbon (activated carbon), or the like.

According to an embodiment of the present invention, the polymer binder may be PVDF (polyvinylidene fluoride).

According to an embodiment of the present invention, in the step (b1), the transition metal oxide nanoparticles, the carbon additive, and the polymeric binder are mixed at an X: X: Y ratio (2X + Y = 1) The catalyst mixture can be prepared.

Also, according to an embodiment of the present invention, the Y may have a value of 0.1 to 0.9.

According to an embodiment of the present invention, in the step (b2), the organic solvent may include at least one of N-methyl-2-pyrrolidone (NMP), ethanol and methanol.

According to an embodiment of the present invention, in the step (b), the thickness of the layer to be laminated may be 70 nm to 600 nm.

According to an embodiment of the present invention, there is also provided a method of manufacturing a semiconductor device, comprising the steps of: (c) immersing the conductive substrate in a metal ion solution; And (d) aging the metal ion solution immersed in the conductive substrate at a predetermined temperature.

According to an embodiment of the present invention, the metal ion solution may include iridium (Ir), cobalt (Co), copper (Cu), nickel (Ni), iron (Fe), chromium (Cr), ruthenium , Gold (Au), platinum (Pt), palladium (Pd) and rhodium (Rh).

Also, according to an embodiment of the present invention, the transition metal oxide nanoparticles include a trivalent transition metal, and may be non-stoichiometric (expressed as A _{1 隆} O (A is a transition metal, 0 & non-stoichiometric transition metal oxide nanoparticles.

According to an embodiment of the present invention, the trivalent transition metal and the divalent transition metal may be positioned on the surface of the transition metal oxide.

According to an aspect of the present invention for solving the above problems, there is provided a catalyst formed on a conductive substrate and having a plurality of layers composed of the transition metal oxide nanoparticles stacked.

According to an aspect of the present invention for solving the above problems, the catalyst can be produced using any one of the catalyst production methods described above.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a conductive substrate; And a catalyst formed on the conductive substrate, the catalyst comprising a plurality of stacked layers of the transition metal oxide nanoparticles.

According to an aspect of the present invention, there is provided a method of fabricating an electrode including a conductive substrate and a catalyst formed on the conductive substrate and including a plurality of layers of the transition metal oxide nanoparticles stacked in layers, Is used as an anode in an electrochemical reaction system.

According to one embodiment of the present invention as described above, the present invention can be applied to various chemical reactions for generating high stability and chlorine, has high catalytic efficiency, and has high economic efficiency. Of course, the scope of the present invention is not limited by these effects.

FIG. 1 is a flowchart illustrating a process of producing a catalyst and generating chlorine according to an embodiment of the present invention. Referring to FIG.
FIG. 2 is a schematic view showing coating of metal oxide nanoparticles on a conductive substrate according to an embodiment of the present invention. FIG.
3 is a schematic view illustrating a catalyst manufacturing process according to another embodiment of the present invention.
4 is a schematic perspective view of a nanostructure containing a transition metal oxide according to an embodiment of the present invention.
5 is a TEM photograph of a transition metal oxide according to an embodiment of the present invention.
6 is a TEM photograph of a nanostructure containing a transition metal oxide according to an embodiment of the present invention.
7 is a TEM photograph showing a metal oxide nanoparticle coated on a conductive substrate according to an embodiment of the present invention in front view.
FIG. 8 is a cross-sectional TEM image of metal oxide nanoparticles coated on a conductive substrate according to an embodiment of the present invention.
9 to 13 are graphs showing catalyst characteristics of metal oxide nanoparticle layers according to an embodiment of the present invention.
14 is a graph showing the catalytic properties of the metal oxide nanoparticle layers according to various embodiments of the present invention.
15 is a schematic diagram of a chlorine generating electrochemical reaction system comprising a catalyst according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views, and length and area, thickness, and the like may be exaggerated for convenience.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

Transition metal oxide, catalyst production

FIG. 1 is a flowchart illustrating a process of producing a catalyst and generating chlorine according to an embodiment of the present invention. Referring to FIG. FIG. 2 is a schematic view showing coating of metal oxide nanoparticles on a conductive substrate according to an embodiment of the present invention. FIG.

The method of manufacturing a catalyst according to an embodiment of the present invention includes the steps of: (a) preparing a transition metal oxide nanoparticle 100; and (b) forming a transition metal oxide nanoparticle 100 on the conductive substrate 10, (20) of a plurality of layers constituted by a plurality of layers. Then, chlorine is produced in the electrochemical reaction system using the catalyst (S30).

First, (a) the transition metal oxide nanoparticles 100 are prepared (S10).

The process for preparing the transition metal oxide nanoparticles 100 comprises the steps of (a1) preparing a first solution containing a transition metal ion supplying material and a fatty acid surfactant, (a2) preparing a second solution containing an alcohol surfactant, (A3) aging the first solution and the second solution at a predetermined temperature, (a4) introducing the second solution into the first solution to produce transition metal oxide nanoparticles, (a5) Aging the metal oxide nanoparticles at a predetermined temperature, and (a6) surface-treating the transition metal oxide nanoparticles.

The transition metal may be any one of Mn, Co, Cu, Ni, and Fe. Hereinafter, description will be made assuming that the manganese oxide nanoparticles 100 are the main examples.

In step S11 of producing a first solution containing a transition metal ion supplying material and a fatty acid surfactant, the transition metal ion supplying material and the fatty acid surfactant may be mixed in an organic solvent to prepare a first solution. The fatty acid surfactant assists dissolution of the transition metal ion supply material and can be used for dispersion of the transition metal oxide nanoparticles formed in the subsequent step S14.

The fatty acid surfactant may be, for example, myristic acid, stearic acid, oleic acid, etc., and may be in a solution state having a concentration of 0.1 M to 0.5 M. The transition metal ion supplying material may be a transition metal acetate, for example, manganese acetate may be used to supply manganese ions. The first solution may be a cationic solution, and the concentration of the cation may be 0.5 mM to 2 mM.

In a step (S12) of preparing a second solution comprising an alcohol surfactant, the alcohol surfactant may be, for example, decanol, myristyl alcohol, stearyl alcohol, And may be mixed with an organic solvent to prepare a second solution. Alcohol surfactants may be involved in nucleation and growth. In steps S11 and S12, the organic solvent may be, for example, octadecene or hexadecylamine.

The step of aging the first and second solutions (S13) may be carried out at a temperature of 250 ° C to 300 ° C, respectively, and the temperature may be kept constant during the ripening period. The aging time can be, for example, about one hour each.

Transition metal oxide nanoparticles may be formed by hot injection and pyrolysis in a step of injecting the second solution into the first solution to form transition metal oxide nanoparticles (S14). This step can be carried out at a temperature of 250 ° C to 300 ° C.

The step (S15) of aging the transition metal oxide nanoparticles at a predetermined temperature may be performed for 1 minute to 24 hours after the second solution is introduced, and the size of the transition metal oxide nanoparticles prepared through the aging time adjustment is Lt; / RTI > The size of the transition metal oxide nanoparticles may be, for example, 1 nm to 100 nm. In one embodiment, the size of the manganese oxide nanoparticles may be determined by the ratio of the manganese ion feed material to the fatty acid surfactant, and the ratio may range, for example, from 1: 2 to 1: 6. The lower the ratio of the fatty acid surfactant, the smaller the size of the manganese oxide nanoparticles.

The step (S16) of surface-treating the transition metal oxide nanoparticle may be a step for removing the ligand on the surface of the transition metal oxide nanoparticle. Since the ligand is formed by adsorbing a fatty acid surfactant on the surface of the transition metal oxide nanoparticles and the conductivity is deteriorated, it is necessary to remove the transition metal oxide nanoparticles as a catalyst. This step, for example, be carried out in a basic solution such as ammonia water (NH ₄ OH), sodium hydroxide (NaOH), by immersing the prepared transition metal oxide nanoparticles. Alternatively, this step may be performed by heat treatment. In particular, the surface of the transition metal oxide nanoparticles may be partially oxidized by this step, and the transition metal oxide nanoparticles may include trivalent manganese (Mn ^Ⅲ ).

The transition metal oxide 100 produced by this embodiment may have a non-stiochiometric composition and may be represented by the following formula (1).

[Chemical Formula 1]

A _1-隆 O

In the above formula (1), A is any one of Mn, Co, Cu, Ni and Fe as a transition metal, and δ satisfies 0 <δ <0.5.

Nonstoichiometric composition can be understood to mean a thermodynamically stable quantitative relationship of the transition metal and oxygen in the compound (100) composed of a transition metal and oxygen. For example, in the case of manganese oxide, the stoichiometric manganese oxide may include _{MnO, Mn 3 O 4, Mn} 2 O 3 and MnO _2. Therefore, the manganese oxide can be specifically a composition except for the case where? Is 0.25 and 1/3. That is,? Can satisfy the range of 0 <? <0.25, 0.25 <? <1/3, 1/3 <? <0.5.

The transition metal oxide 100 may include a trivalent transition metal (e. G., Trivalent manganese Mn ^III ), and a trivalent transition metal may be located on the surface of the transition metal oxide. The trivalent transition metal located on the surface of the transition metal oxide 100 may be thermodynamically unstable. In addition, the trivalent transition metal located on the surface of the transition metal oxide 100 may be in the form of a defect which is not located in the lattice structure. The trivalent transition metal and the divalent transition metal may all be located on the surface of the transition metal oxide (100).

1 and 2, the transition metal oxide nanoparticles 100 may be coated on the conductive substrate 10 after the transition metal oxide nanoparticles 100 are manufactured (S20) . At this time, a plurality of layers composed of the transition metal oxide nanoparticles 100 can be stacked.

The process of laminating a plurality of layers composed of the transition metal oxide nanoparticles 100 includes the steps of (b1) preparing a catalyst mixture by mixing the transition metal oxide nanoparticles 100 with a carbon additive and a polymeric binder (S21 (b2) a step (S22) of preparing a third solution in which the catalyst mixture is dispersed in an organic solvent, and (b3) a step (S23) of applying a third solution on the conductive substrate 10 .

A carbon nanotube, a carbon fiber, an artificial graphite, a carbon nanotube, a carbon nanotube, a carbon nanotube, and a carbon nanotube are mixed in a step S21 of preparing a catalyst mixture by mixing the transition metal oxide nanoparticles 100 with a carbon additive and a polymer binder. A carbon additive including any one of carbon black, artificial graphite, carbon black, and activated carbon may be used. It is preferable that the carbon additive is composed of nano-sized particles. As the polymer binder, PVDF (polyvinylidene fluoride) or the like may be used.

The catalyst mixture can be prepared by mixing the transition metal oxide nanoparticles (100), the carbon additive, and the polymer binder in the weight ratio of X: X: Y, respectively. At this time, 2X + Y = 1 is satisfied, and Y is mixed so as to have a value of 0.1 to 0.9.

In the step S22 of preparing the third solution in which the catalyst mixture is dispersed in the organic solvent, the catalyst mixture may be dispersed in an organic solvent such as N-methyl-2-pyrrolidone (NMP), ethanol or methanol.

In step S23 of applying the third solution on the conductive substrate 10, it is preferable to use spin coating. In addition to this, the catalyst mixture may be formed into a paste and applied, or may be formed into an ink and subjected to drop casting. A plurality of layers composed of the transition metal oxide nanoparticles 100 can be stacked 20 by applying the third solution on the conductive substrate 10. [ The transition metal oxide nanoparticles 100 may be stacked to form a close packing.

At this time, the thickness t to be laminated may be 70 nm to 600 nm. In the course of spin coating or drop casting, the thickness t of the deposited metal nanoparticles 100 may be adjusted by adjusting the concentration of the transition metal oxide nanoparticles 100 included in the third solution. The concentration can be adjusted from 0.01 g / ml to 50 g / ml.

Electrons can move along the surface of the transition metal oxide nanoparticles (100) in the layered body (20) of the transition metal oxide nanoparticles (100). During the catalytic reaction, the electrons and the hydrogen cation particles existing in the electrolyte are coupled and can move together. Thus, a combination of the conductive metal oxide nanoparticle layers laminated on the conductive substrate 10 and the conductive substrate 10 as a plurality of layers can be used as a catalyst.

As a next step, chlorine can be produced in the electrochemical reaction system using a catalyst (S30).

A catalyst formed on the conductive substrate 10 and having a plurality of layers of the transition metal oxide nanoparticles 100 stacked thereon can be used as an electrode in an electrochemical reaction system, As shown in Fig. The electrolyte may be composed of a mixed solution comprising NaCl, NaClO _4, etc., Cl. For example, a mixed solution of NaCl (x M) and NaClO ₄ (4-x M), and x = 10 mM to 6M.

In the anode, an oxidation reaction occurs to generate chlorine (Cl ₂ ), hypochlorous acid (HOCl), hypochlorite (OCl ^- ), and the like, and a reduction reaction occurs in the cathode to generate hydrogen. The reaction formula is as follows.

(I) 2Cl ^- -> Cl ₂ + 2e ^-

(Ii) Cl ₂ + H ₂ O -> H ⁺ + HOCl + Cl ^-

(Iii) HOCl + H ₂ O -> OCl ^- + H ₃ O ⁺

Chlorine (Cl ₂ ), hypochlorous acid (HOCl), hypochlorite (OCl ^- ) produced through the above (i), (ii) and (iii) can cause disinfection.

On the other hand, OH ^- paper can be produced as a byproduct while generating hydrogen at the cathode. This can increase the pH of all electrochemical cells and cause a phenomenon of inhibiting Cl ₂ generation. Therefore, in the electrochemical reaction system of the present invention, a separation membrane between the anode and the cathode is essentially required. The constituents of the membrane may be Nafion, cation exchange membrane, and the like.

In addition, the catalyst of the present invention can be used as a catalyst in various electrochemical reactions such as oxidation / reduction reactions.

3 is a schematic view illustrating a catalyst manufacturing process according to another embodiment of the present invention. 4 is a schematic perspective view of a nanostructure containing a transition metal oxide according to an embodiment of the present invention.

(C) immersing the conductive substrate 10 in the metal ion solution (S21) and (d), the step (d) of immersing the conductive substrate 10 in the metal ion solution, And aging the metal ion solution immersed in the conductive substrate 10 at a predetermined temperature (S22).

In the step S21 of immersing the conductive substrate 10 in the metal ion solution, the metal ion solution is iridium (Ir), cobalt (Co), copper (Cu), nickel (Ni), iron (Fe) ), Ruthenium (Ru), gold (Au), platinum (Pt), palladium (Pd) and rhodium (Rh). The metal ion solution may include at least one of acetate, nitrate, and chloride. The concentration of metal cations in the metal ion solution may be from 1 mM to 50 mM.

(Or the surface of the layered body of transition metal oxide nanoparticles) of the transition metal oxide nanoparticles 110 is aged through a step S22 of aging the metal ion solution immersed in the conductive substrate 10 at a predetermined temperature, (120) may be formed.

Referring to FIG. 4, according to the embodiment, nanocore 110, which is manganese oxide nanoparticles containing trivalent manganese, and nanostructure 120, which includes metal nanoparticles 120 adsorbed on the surface of nanocore 110, (100 ') can be produced.

The nanocore 110 may have a non-stoichiometric composition and may be represented by the following formula (1). As an example, the nanocore 110 may include trivalent manganese (Mn ^III ) on its surface.

The metal nanoparticles 120 may be formed of at least one selected from the group consisting of Ir, Co, Cu, Ni, Fe, Cr, Ru, Au, (Pt), palladium (Pd), rhodium (Rh), and alloys thereof.

A plurality of metal nanoparticles 120 may be formed on the surface of one nanocore 110. The size D1 of the nanocore 110 may be 20 nm or less, particularly 10 nm or less, and the size D2 of the metal nanoparticle 120 may be 1 nm to 10 nm, particularly 3 nm or less.

Transition metal oxide, structure of catalyst

5 is a TEM photograph of a transition metal oxide according to an embodiment of the present invention.

Referring to FIG. 5A, the manganese oxide nanoparticles prepared according to steps S10 (S11-S16) of the embodiment of FIG. 1 were analyzed by a transmission electron microscope (TEM). According to this, the manganese oxide nanoparticles have a size of 10 nm or less. Further, according to the result of the diffraction pattern analysis by TEM, the (200) plane and the (111) plane which are the crystal planes of the manganese oxide having the composition of MnO can be indexed.

Referring to FIG. 5 (b), manganese oxide nanoparticles prepared according to the step S10 (S11-S16) of the embodiment of FIG. 1 were analyzed by TEM. Specifically, the manganese oxide nanoparticles used in the analysis were treated with ammonia water (NH ₄ OH) for 1 hour in step S16. According to Fig. 5 (b), the manganese oxide nanoparticles may have a size of 10 nm or less. Further, according to the results of the TEM diffraction pattern analysis, the (10-1) plane and the (-112) plane, which are the crystal planes of the manganese oxide having the composition of Mn3O4, ) Plane. &Lt; / RTI &gt; Therefore, it can be seen that the surface of the produced manganese oxide nanoparticles is partially oxidized by the step S16.

6 is a TEM photograph of a nanostructure containing a transition metal oxide according to an embodiment of the present invention.

Referring to Figures 6 (a) and 6 (b), nanostructures 100 'comprising manganese oxide prepared according to the embodiment of Figures 3 and 4 were analyzed by TEM. The nanostructure 100 'may include a nanocore 110 of manganese oxide and metal nanoparticles 120 adsorbed on the nanocore. The metal nanoparticles 120 can be adsorbed substantially uniformly on the surface of the nanocore 110. In particular, in this embodiment, the metal nanoparticles 120 may include iridium (Ir).

7 is a TEM photograph showing a metal oxide nanoparticle 100 (laminate 20) coated on a conductive substrate 10 according to an embodiment of the present invention in front view. 8 is a TEM photograph showing a cross section of a metal oxide nanoparticle 100 (laminate 20) coated on a conductive substrate 10 according to an embodiment of the present invention.

Referring to FIG. 7 (a), it is confirmed that the metal oxide nanoparticles 100 are uniformly arranged and formed on the conductive substrate 10. 7 (b), the metal oxide nanoparticles 100 are uniformly arranged in the respective layers, and the respective layers are densely laminated 20, As shown in FIG.

8 (a), 8 (b), and 8 (c) show the thicknesses of the metal oxide nanoparticles 100 in a thickness of 70 nm, 150 nm, Sectional view showing a cross-sectional view of a light emitting device 20 according to the present invention. In each case, it can be confirmed that the layered product 20 is formed with a relatively uniform thickness.

Analysis of catalyst characteristics

9 to 13 are graphs showing catalyst characteristics of metal oxide nanoparticle layers according to an embodiment of the present invention.

Hereinafter, the catalytic characteristics are obtained by mixing the transition metal oxide nanoparticles 100 having a size of about 10 nm manufactured according to the embodiments of the present invention with the carbon additive, drying the mixture to form powders, And then coating the powder to form the layered body 20 to prepare an electrode and measuring the electrochemical characteristics.

The powder may be coated on the conductive substrate 10 by, for example, spin coating, in which case the rotational speed may range from 2000 rpm to 4000 rpm. Also, the coating time may be in the range of 10 seconds to 60 seconds, and the thickness of the laminate 20 may be adjusted by controlling the time and the number of repetitions. The electrochemical characteristics can be measured using a 3-electrode cell or a 2-electrode cell filled with a buffer electrolyte aqueous solution. Specifically, in the case of a three-electrode cell, a counter electrode composed of a working electrode coated with a catalyst, a platinum (Pt) wire or a platinum (Pt) plate, and a reference electrode of silver / silver chloride A reference electrode, and a two-electrode cell may be configured as a working electrode and a counter electrode without a reference electrode. Sodium phosphate or potassium phosphate solution having a pH of 7.8 was used as the buffer electrolyte aqueous solution.

9, when the layered body 20 of the transition metal oxide nanoparticles 100 according to an embodiment of the present invention is used, a cyclic voltammogram according to the thickness of the layered body 20 is obtained Standard hydrogen electrode (NHE).

When the thickness of the layered body 20 was 70 nm, the lowest characteristic was exhibited, and the thicker the thickness was, the better the characteristic was exhibited. However, it was confirmed that the characteristics were improved up to 300 nm, and further decreased at the thickness exceeding 300 nm. These values show high activity when compared with manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu)

Referring to Figs. 9 and 10, measurement results of Tafel inclination are shown. Tapsel slope is a measure of electrode activity and represents the voltage required to increase the current by 10 times. In the case of this embodiment, the inclination of the Tappel indicating the electrochemical reaction rate is about 85 mV / decade (70 nm), about 70 mV / decade (150 nm), about 67 mV / decade , And about 82 mV / decade (600 nm). This other manganese oxide having a tapel slope of about 120 mV / decade (MnO, Mn 3 O 4, Mn 2 O 3 and MnO ₂₎ and compared to a low value, high activity body of this embodiment lamination of manganese oxide nanoparticles As shown in FIG. Particularly, it can be confirmed that excellent activity is obtained in a laminate having a thickness of 300 nm.

Referring to FIG. 12, measurement results of impedance according to the thickness of a monolayer or laminate 20 are shown. It can be confirmed that when the layered body 20 is formed with a thickness of 300 nm and 600 nm, the transition metal oxide nanoparticles 100 are arranged in a single layer, and the impedance is low.

Referring to FIG. 13, the pH dependency of the thickness of the laminate 200 is shown. The higher the pH, the higher the current density at the same potential. This may be because the proton is involved in the electrochemical reaction. It is also found that the catalyst has relatively excellent catalytic properties even at pH 7.0, which is a neutral condition.

14 is a graph showing the catalytic properties of the metal oxide nanoparticle layers according to various embodiments of the present invention.

A catalyst in which transition metal oxide nanoparticles 100 are formed of MnO and CoO in a layered structure 20 and a nanostructure 100 'in which Ir is formed as metal nanoparticles 120 on the surface of transition metal oxide nanoparticles 110, ) Catalyst. This is laminated on the conductive substrate 10 such as FTO, ITO, Carbon paper or the like through spin coating. 4M NaCl was used as an electrolyte for Cl ₂ generation and NaClO ₄ was used for comparison. H-Cell was used as a driving device and Nafion was used as a separation membrane.

Referring to FIG. 14, it can be seen that most of the measured values show high activity as compared with manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) In particular, it can be seen that the nanostructure (100 ') catalyst in which the metal nanoparticles 120 are formed on the surface of the transition metal oxide nanoparticles 110 exhibits higher activity.

Electrochemical reaction system application example

15 is a schematic diagram of a chlorine generating electrochemical reaction system comprising a catalyst according to an embodiment of the present invention.

15, a brine dissolution system 200 includes an electrolyzer 210, a buffer electrolyte aqueous solution 220, a first electrode 230 and a second electrode 240 can do. The first and second electrodes 230 and 240 may be connected by a power source. In one embodiment, the water splitting system 200 may further include an ion exchange portion between the first and second electrodes 230, 240.

The first and second electrodes 230 and 240 may be made of a semiconductor or a conductive material, respectively. Particularly, the first electrode 230 may be the conductive substrate 10 described above, and the chlorine generating catalyst 260 may be a transition metal oxide, such as a transition metal oxide, in accordance with the embodiment of the present invention described above with reference to FIGS. Nanoparticle laminate 200 (or nanostructure 100 'laminate). Or the first electrode 230 may be separately formed and the conductive substrate 10 and the layered body 20 may be connected to one surface of the first electrode 230.

The electrolyzer 210 may further include an inlet and an outlet such as a water inlet pipe and a drain pipe.

The buffer electrolyte aqueous solution 220 may serve as a source of a brine source used in a saltwater decomposition reaction and a receptor of a proton generated in a saltwater decomposition reaction. The buffer electrolyte aqueous solution 220 may include at least one of potassium phosphate and sodium phosphate, for example, KH ₂ PO ₄ , K ₂ HPO ₄ , K ₃ PO _4, or a mixture thereof. The pH of the buffer electrolyte aqueous solution 220 may be 2 to 14. In particular, when the chlorine-generating catalyst 260 of the present invention is used, the buffer electrolyte aqueous solution 220 may have a neutral condition. For the role of the proton as a receptor, the buffer electrolyte aqueous solution 220 may include a proton-accepting anion. Accordingly, even when the amount of the proton (H ⁺ ) to be produced increases with the progress of the saltwater decomposition reaction, the proton-soluble anion can accommodate at least a part of these protons, and the pH reduction rate of the buffer electrolyte aqueous solution 220 can be lowered. The proton-accepting anion may include at least one of a phosphate ion, an acetate ion, a borate ion, and a fluoride ion.

When a voltage is applied between the first and second electrodes 230 and 240 in the salt water decomposition system 200, chlorine is generated in the first electrode 230 and a reaction in which hydrogen is generated in the second electrode 240 . Each half-reaction can be expressed by the following equations (1) and (2).

[Reaction 1] 2Cl ^- -> Cl ₂ + 2e ^-

Cl ₂ + H ₂ O -> H ⁺ + HOCl + Cl ^-

2H ⁺ + 2e ^- &gt; H ₂

The chlorine generating catalyst 260 according to the embodiment of the present invention may participate in the reaction at the first electrode 230 represented by the reaction formula 1. Thereby, the saltwater decomposition reaction can be carried out at a low overcharge even under neutral conditions. On the other hand, both chlorine and oxygen can be produced by causing an oxidation reaction at the anode. The voltage used to generate chlorine in the brine decomposition is 1.36 V, while the voltage used to generate oxygen in water decomposition is 1.23 V, but four electrons are involved in generating oxygen in water decomposition. Therefore, there is a high possibility that chlorine is generated thermally in a competitive relationship between chlorine and oxygen, and the present invention can provide a catalyst capable of generating chlorine in a competitive reaction.

Although the system including the chlorine generating catalyst according to the embodiment of the present invention has been exemplarily described as a brine decomposition system, the present invention is not limited thereto and may be used in various electrochemical reaction systems.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such variations and modifications are to be considered as falling within the scope of the invention and the appended claims.

10: Conductive substrate
20: A laminate of transition metal oxide nanoparticle layers
100: transition metal oxide nanoparticles
100 ': nanostructure in which metal nanoparticles are formed on the surface of transition metal oxide nanoparticles

Claims (17)

(a) preparing transition metal oxide nanoparticles; And
(b) stacking a plurality of layers made of said transition metal oxide nanoparticles on a conductive substrate
Lt; / RTI &gt;
Wherein the transition metal oxide nanoparticles comprise a trivalent transition metal,
A _1-δ O (A is a transition metal, 0 <δ <0.25, 0.25 <δ <1/3, 1/3 <δ <0.5)
Wherein the catalyst is a non-stoichiometric transition metal oxide nanoparticle represented by the following formula (1). The method according to claim 1,
The step (a)
(a1) preparing a first solution comprising a transition metal ion supply material and a fatty acid surfactant;
(a2) preparing a second solution comprising an alcohol surfactant;
(a3) aging the first solution and the second solution at a predetermined temperature;
(a4) introducing the second solution into the first solution to prepare the transition metal oxide nanoparticles;
(a5) aging the transition metal oxide nanoparticles at a predetermined temperature; And
(a6) a step of surface-treating the transition metal oxide nanoparticles
&Lt; / RTI &gt; The method according to claim 1,
The step (b)
(b1) preparing a catalyst mixture by mixing the transition metal oxide nanoparticles with a carbon additive and a polymeric binder;
(b2) preparing a third solution in which the catalyst mixture is dispersed in an organic solvent; And
(b3) applying the third solution onto the conductive substrate
&Lt; / RTI &gt; The method of claim 3,
The carbon additive may be at least one selected from the group consisting of Graphene, Carbon Nanotube, Carbon Fiber, Artificial Graphite, Carbon Black and Activated Carbon. &Lt; / RTI &gt; The method of claim 3,
Wherein the polymer binder is PVDF (polyvinylidene fluoride). The method of claim 3,
In the step (b1)
Wherein the transition metal oxide nanoparticles, the carbon additive, and the polymer binder are mixed at an X: X: Y weight ratio (2X + Y = 1, and Y has a value of 0.1 to 0.9) Gt; delete The method of claim 3,
In the step (b2), the organic solvent includes at least one of N-methyl-2-pyrrolidone (NMP), ethanol and methanol. The method according to claim 1,
In the step (b), the thickness to be laminated is 70 nm to 600 nm. The method according to claim 1,
(c) immersing the conductive substrate in a metal ion solution; And
(d) aging the metal ion solution in which the conductive substrate is immersed at a predetermined temperature
&Lt; / RTI &gt; 11. The method of claim 10,
The metal ion solution may be at least one selected from the group consisting of Ir, Co, Cu, Ni, Fe, Cr, Ru, Au, Wherein the catalyst comprises at least one cation selected from the group consisting of palladium (Pd) and rhodium (Rh). delete The method according to claim 1,
Wherein the trivalent transition metal and the divalent transition metal are located on the surface of the transition metal oxide. A plurality of layers of transition metal oxide nanoparticles formed on a conductive substrate,
Wherein the transition metal oxide nanoparticles comprise a trivalent transition metal,
A _1-δ O (A is a transition metal, 0 <δ <0.25, 0.25 <δ <1/3, 1/3 <δ <0.5)
Wherein the catalyst is a non-stoichiometric transition metal oxide nanoparticle. A catalyst prepared using any one of the methods of claims 1 to 6, 8 to 11 and 13. Conductive substrate; And
A catalyst formed on the conductive substrate, in which a plurality of layers of transition metal oxide nanoparticles are stacked
Lt; / RTI &gt;
Wherein the transition metal oxide nanoparticles comprise a trivalent transition metal,
A _1-δ O (A is a transition metal, 0 <δ <0.25, 0.25 <δ <1/3, 1/3 <δ <0.5)
Wherein the non-stoichiometric transition metal oxide nanoparticles are represented by the following formula (1). An electrode comprising a conductive substrate and a catalyst formed on the conductive substrate in the form of a plurality of stacked layers of transition metal oxide nanoparticles is used as an anode,
Wherein the transition metal oxide nanoparticles comprise a trivalent transition metal,
A _1-δ O (A is a transition metal, 0 <δ <0.25, 0.25 <δ <1/3, 1/3 <δ <0.5)
Wherein the electrochemical reaction system is a non-stoichiometric transition metal oxide nanoparticle.

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