KR102425951B1 - Method of preparing transition metal nanoparticle-decorated manganese oxide nanorod electrocatalysts and nanorod electrocatalysts prepared thereby - Google Patents

Abstract

The present invention provides an electrodecatalyst which is cheaper than Pt-C which is currently widely used commercially and has excellent electrochemical activity comparable thereto, and a preparation method thereof. The catalyst of the present invention is prepared through a combustion path and transition metal nanoparticles are decorated on manganese oxide.

Description

Manufacturing method of manganese oxide nanorod electrocatalyst decorated with transition metal nanoparticles and nanorod electrocatalyst prepared thereby

The present invention relates to a catalyst for a fuel cell and a method for preparing the catalyst. More specifically, it relates to a catalyst for a fuel cell, an electrode, and an electrochemical reaction applicable to various electrochemical catalytic reactions such as water decomposition oxidation/reduction reaction, hydrogen production reaction, and CO ₂ reduction reaction.

A fuel cell is a device that converts chemical energy into electrical energy, and it is a future alternative energy technology that has the advantage of being more efficient than the existing internal combustion engine and emitting almost no pollutants.

A fuel cell is generally composed of an oxidizing electrode, a reducing electrode, and an electrolyte, and is largely classified into a low-temperature type and a high-temperature type depending on the electrolyte used. In the case of a low-temperature fuel cell with an operating temperature of 300° C. or less, a desired amount of energy can be obtained by having high catalytic reactivity and ion permeability at a low temperature. Currently, platinum is widely used as an electrode catalyst for fuel cells in the industry. Since platinum itself is expensive, it is very important to reduce the amount of platinum used or to maximize the activity per unit weight. In order to achieve the above object and increase the reactive active area of the catalyst, the size of the platinum particles should be adjusted to a nano size. However, even if the size of the platinum particles is adjusted to a nano size, Pt-C is limited as a catalyst due to lack of stability. For example, a fuel cell powered vehicle needs to be stopped and started. During higher cathode potentials, the platinum of the electrocatalyst and some of the carbon support tend to oxidize, causing dissolution of platinum ions during carbon corrosion. Platinum ions are mobile at least to the proton conducting membrane. Hydrogen passing through the proton-conducting membrane at the anode subsequently reduces the platinum ions to platinum nanoparticles. Therefore, while platinum is depleted at the cathode, if platinum accumulates in the proton conducting film, it prevents hydrogen from moving to the cathode and the electron conductivity is slowed down due to carbon corrosion. This problem causes potential loss during operation of the fuel cell, thereby reducing fuel cell efficiency.

In order to solve the above problems, the present inventors have come to develop a transition metal oxide-based electrocatalyst that is economical, easy to manufacture, and resistant to oxidation and dissolution effects. Therefore, the electrocatalyst of the present invention can greatly promote the commercialization of fuel cells as an efficient catalyst in terms of cost and function by replacing the existing Pt-C. The present invention is a transition metal-Mn _x O _y composite electrocatalyst, wherein the transition metal-Mn _x O _y composite particles have a Mn _x O _y core partially encapsulated by a thin layer of valence zero or partially charged metal atoms. includes That is, the Mn _x O _y core is bound to a zero-valence or partially charged metal cluster. The thin layer may be a sub-monolayer, a single layer, a double layer or a triple layer. The present invention with these characteristics has comparable or improved durability to Pt-C. That is, since the bonding interaction between M _x O _y serving as a support in the present invention and the transition metal is stronger than the bonding between platinum and carbon support of Pt-C, the problem of metal leaching can be suppressed. It will be possible to precisely control the crystal structure and phase of the transition metal oxide support, which is much more stable under operating conditions such as fuel cells.

An object of the present invention is to provide a method for manufacturing an electrode catalyst for a fuel cell that has high stability and can be used for various chemical reactions.

Another object of the present invention is to provide a method for preparing an electrode catalyst for a fuel cell having high catalytic efficiency.

Another object of the present invention is to provide a method for manufacturing an electrode catalyst for a fuel cell that is highly economical.

Another object of the present invention is to provide a method for manufacturing an electrode catalyst for a fuel cell with high efficiency due to a simple manufacturing process.

Another object of the present invention is to provide an electrode catalyst for a fuel cell prepared by the above method.

The above objects of the present invention can all be achieved by the present invention described below and are not limited to the above-mentioned objects.

In order to solve the above problems, the nanorod electrocatalyst of the present invention is a manganese oxide decorated with monodisperse transition metal nanoparticles (NPs), has a heterostructure in which oxygen deficiency exists, and is represented by the following Chemical Formula 1:

[Formula 1] A-Mn _x O _y

In Formula 1, A is gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), silver (Ag), nickel (Ni), iron (Fe), from the group consisting of cobalt (Co) It may include at least one selected element, x is 1≤x≤3, y is 1≤y≤7. Manganese oxides decorated with transition metal nanoparticles (NPs) contain a Mn _x O _y core partially encapsulated by a thin layer of zero valence or partially charged metal atoms.

Mn _x O _y serving as a support in Formula 1 is MnO, Mn ₃ O ₄ , Mn ₂ O ₃ , α-MnO ₂ , β-MnO ₂ , γ-MnO ₂ , δ-MnO ₂ , MnO ₃ , Mn It may be any one of ₂ O ₇ and Mn ₂ O ₄ .

The method for preparing a nanorod electrocatalyst of the present invention comprises:

preparing a manganese precursor aqueous solution by dissolving the manganese precursor in distilled water;

adding fuel to the aqueous manganese precursor solution under stirring;

generating a manganese oxide decorated with monodispersed transition metal nanoparticles (NPs) by adding a transition metal compound solution and a complexing agent to the aqueous manganese precursor solution;

stirring to gel the manganese oxide;

heating to remove volatile impurities from the gelled manganese oxide and solidify;

pulverizing the solidified manganese oxide to obtain a powdery mixture; and

and calcining the mixture to remove volatile impurities and increase crystallinity.

The manganese precursor is characterized in that at least one selected from manganese nitrate, manganese acetate, and manganese sulfate.

The fuel is urea (CH ₄ N ₂ O), glycine (C ₂ H ₅ NO ₂ ), glucose (C ₆ H ₁₂ O ₆ ), sucrose (C ₁₂ H ₂₂ O ₁₁ ), carbohydrazide ( CH ₆ N ₄ O), oxalidahydrazide (C ₂ H ₆ N ₄ O ₂ ), hexamethylenetetramine (C ₆ H ₁₂ N ₄ ) and acetylacetone (C ₅ H ₈ O ₂ ) at least one selected from it could be

The complexing agent may be one or more selected from citric acid and tannic acid as a reducing agent, and is added in an amount of 2:1 with a cationic metal.

The aqueous solution of the manganese precursor is mixed with the fuel in a 2:1 ratio at room temperature and stirred.

10 to 20 wt% of the transition metal compound solution is added to the manganese precursor aqueous solution, and then a complexing agent is added.

The transition metal compound may be at least one selected from transition metal nitrate, transition metal acetate, and transition metal halide.

The manganese oxide decorated with the monodisperse transition metal nanoparticles may have a heterostructure in which oxygen deficiency exists.

In the stirring step to gel the manganese oxide, stirring is performed at 50 to 90° C. until 60% to 70% of the solvent is evaporated to form a gel.

The step of heating to remove volatile impurities from the gelled manganese oxide and solidify is performed under a mixed gas of an inert gas such as hydrogen (H ₂ ) gas and nitrogen (N ₂ ) gas. The hydrothermal synthesis temperature is increased to 200 to 250° C. for 2 to 5 hours to remove impurities and solidify manganese oxide. Hydrogen gas in the mixed gas has 10 to 40 vol%.

The solidified manganese oxide is pulverized using a mortar to make a powder mixture, and the particle size of the powder mixture is 20 nm or more and 100 nm or less.

The step of calcinating the mixture to remove volatile impurities and increase crystallinity is performed at 500 to 800° C. for 1 to 4 hours.

Hereinafter, the specific content of the present invention will be described in detail.

According to the method for producing an electrocatalyst according to the present invention and the electrocatalyst prepared thereby, it is possible to prevent separation of the catalyst and the support generated in the electrode, and thus has high stability and high catalytic efficiency. In addition, it is possible to simplify the manufacturing process of the electrocatalyst through the solution combustion route and reduce the amount of platinum used, so that it is highly economical. The effects of the present invention are not limited to the above-mentioned effects. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

1 is a result of measuring X-ray diffraction (XRD) of each of Mn _x O _y and Au-Mn _x O _y along a combustion path.
Figure 2 shows the BET (Brunauer- Emmett-Teller) surface area of each of Mn _x O _y and Au-Mn _x O _y along the combustion path.
3 shows images taken with a field emission scanning electron microscope (FESEM) of Mn _x O _y and Au-Mn _x O _y electrocatalysts.
Figure 4a is an irradiation scan image of Mn _x O _y and Au-Mn _x O _y electrocatalyst, Figure 4b is a deconvoluted elemental scan image of Mn2p, Figure 4c is a deconvolted elemental scan image of O1s, 4d is Deconvolted elemental scan images of Au4f spectra of Mn _x O _y and Au-Mn _x O _y electrocatalysts are shown.
5 is Pt-Mn _x O _y , Transmission Electron Microscopy (TEM) and High-Resolution Transmission Electron Microscopy (HR-TEM) images of Pd-Mn _x O _y and Au-Mn _x O _y electrocatalysts.
6 shows stoichiometric amounts of manganese (Mn), oxygen (O) and platinum (Pt) for Pt-Mn _x O _y electrocatalyst; stoichiometric amounts of manganese (Mn), oxygen (O) and palladium (Pd) and Au-Mn _x O _y electrocatalyst for stoichiometric amounts of manganese (Mn), oxygen (O) for Pd-Mn _x O _y electrocatalyst and EDS (Energy Dispersive Spectroscopy) analysis images showing the presence of gold (Au).
7 shows Mn _x O _y , using a rotating disk electrode (RDE). Au-Mn _x O _y , Pt-C, Pt-Mn _x O _y and This is a linear sweep voltammetry (LSV) graph measuring the degree of electrochemical activity of Pd-Mn _x O _y .

Hereinafter, specific embodiments of the present invention will be described in more detail.

The electrocatalyst of the present invention is obtained using a solution combustion route, and since all reactants are put in a single beaker and heated to react, it does not require a separate complicated experimental tool or filtration process, resulting in efficiency and economical efficiency. high.

Electrocatalyst

The nanorod electrocatalyst of the present invention is a manganese oxide decorated with monodisperse transition metal nanoparticles (NPs), has a heterostructure in which oxygen deficiency exists, and is represented by the following Chemical Formula 1:

[Formula 1] A-Mn _x O _y

In Formula 1, A is gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), silver (Ag), nickel (Ni), iron (Fe), from the group consisting of cobalt (Co) It may include at least one selected element, x is 1≤x≤3, y is 1≤y≤7. Manganese oxides decorated with transition metal nanoparticles (NPs) contain a Mn _x O _y core partially encapsulated by a thin layer of zero valence or partially charged metal atoms.

Mn _x O _y serving as a support in Formula 1 is MnO, Mn ₃ O ₄ , Mn ₂ O ₃ , α-MnO ₂ , β-MnO ₂ , γ-MnO ₂ , δ-MnO ₂ , MnO ₃ , Mn It may be any one of ₂ O ₇ and Mn ₂ O ₄ .

Method for manufacturing electrocatalyst

The manufacturing method of the nanorod electrocatalyst of the present invention comprises:

preparing a manganese precursor aqueous solution by dissolving the manganese precursor in distilled water;

adding fuel to the aqueous manganese precursor solution under stirring;

generating a manganese oxide decorated with monodispersed transition metal nanoparticles (NPs) by adding a transition metal compound solution and a complexing agent to the aqueous manganese precursor solution;

stirring to gel the manganese oxide;

heating to remove volatile impurities from the gelled manganese oxide and solidify;

pulverizing the solidified manganese oxide to obtain a powdery mixture; and

and calcining the mixture to remove volatile impurities and increase crystallinity.

The manganese precursor is characterized in that at least one selected from manganese nitrate, manganese acetate, and manganese sulfate.

The fuel is urea (CH ₄ N ₂ O), glycine (C ₂ H ₅ NO ₂ ), glucose (C ₆ H ₁₂ O ₆ ), sucrose (C ₁₂ H ₂₂ O ₁₁ ), carbohydrazide ( CH ₆ N ₄ O), oxalidahydrazide (C ₂ H ₆ N ₄ O ₂ ), hexamethylenetetramine (C ₆ H ₁₂ N ₄ ) and acetylacetone (C ₅ H ₈ O ₂ ) at least one selected from it could be

The complexing agent may be one or more selected from citric acid and tannic acid as a reducing agent, and is added in an amount of 2:1 with a cationic metal. The addition of the complexing agent is to maintain proper homogeneity and viscosity of the mixture.

The aqueous solution of the manganese precursor is mixed with the fuel in a 2:1 ratio at room temperature and stirred. This is called MG (Manganese-Glycine) solution.

10 to 20 wt% of the transition metal compound solution is added to the manganese precursor aqueous solution, and then a complexing agent is added.

The transition metal compound may be at least one selected from transition metal nitrate, transition metal acetate, and transition metal halide.

The manganese oxide decorated with the monodisperse transition metal nanoparticles may have a heterostructure in which oxygen deficiency exists.

In the stirring step to gel the manganese oxide, stirring is performed at 50 to 90° C. until 60% to 70% of the solvent is evaporated to form a gel.

The step of heating to remove volatile impurities from the gelled manganese oxide and solidify is performed through hydrothermal synthesis, that is, under a mixed gas of an inert gas such as hydrogen (H ₂ ) gas and nitrogen (N ₂ ) gas. . The hydrothermal synthesis temperature is increased to 200 to 250° C. for 2 to 5 hours to remove impurities and solidify manganese oxide. However, this is a normal heat treatment temperature, and it is natural that it should be made at a temperature at which thermal decomposition of a material used as a precursor is possible, and an appropriate temperature can be selected according to the type of the precursor, so it is not limited to the above range. The hydrogen (H ₂ ) gas and the reaction under a mixed gas of an inert gas form oxygen defects in the monodisperse transition metal manganese oxide heterostructure as a partial reduction reaction. Hydrogen gas in the mixed gas has 10 to 40 vol%. Such a method is referred to as a solution combustion route.

The solidified manganese oxide is pulverized using a mortar to make a powder mixture, and the particle size of the powder mixture is 20 nm or more and 100 nm or less.

The step of calcinating the mixture to remove volatile impurities and increase crystallinity is performed at 500 to 800° C. for 1 to 4 hours. The calcinating is to obtain a pure phase.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0016] Reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be implemented in other embodiments without departing from the spirit and scope of the invention. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents to those claimed.

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

Example 1 - Au-Mn _x O _y Preparation of nanorod electrocatalyst

Manganese nitrate (Mn(NO ₃ ) ₂ ) (Alfa Aesar) as a manganese precursor, gold(III) chloride (AuCl ₃ ) (Sigma Alderich) as a transition metal compound, and glycine (C ₂ H ₅ NO ₂ ) as a fuel (Alfa Aesar) was used, and citric acid (Alfa Aesar) was used as a complexing agent and a reducing agent. After dissolving 800 mg of manganese nitrate in distilled water to prepare an aqueous precursor solution, 1,600 g of glycine was added under stirring using a magnetic stirrer. This solution was named MG solution. Then, 5 ml of 0.2M choloroauric acid solution was added to the MG solution at 10% by weight, and then 1,200 mg of citric acid was added, and then 80° C. until 60% to 70% of the solvent was evaporated and a gel appeared. It was stirred while maintaining. Then, in order to remove volatile impurities from the gelled manganese oxide and solidify, it was heated in a hydrogen atmosphere (20% (v/v H ₂ /N ₂ )), 200-250° C. for 4 hours. The solidified manganese oxide was pulverized to a powder form of 20 nm or more and 100 nm or less using a mortar. Finally, the powder was heat treated at 500° C. for 2 hours.

Example 2- Pt-Mn _x O _y Preparation of nanorod electrocatalyst

Manganese nitrate (Mn(NO ₃ ) ₂ ) (Alfa Aesar) as a manganese precursor, platinum chloride (PtCl ₄ ) (Sigma Alderich) as a transition metal compound, and glycine (C ₂ H ₅ NO ₂ ) (Alfa) as a fuel Aesar) and citric acid (Alfa Aesar) as a complexing agent and a reducing agent. After dissolving 800 mg of manganese nitrate in distilled water to prepare an aqueous precursor solution, 1,600 g of glycine was added under stirring using a magnetic stirrer. This solution was named MG solution. Then, 5 ml of 0.2M choloroplatinic acid solution was added to the MG solution at 10% by weight, and then 1,200 mg of citric acid was added, and then 80° C. until 60% to 70% of the solvent was evaporated and a gel appeared. It was stirred while maintaining. Then, in order to remove volatile impurities from the gelled manganese oxide and solidify, it was heated in a hydrogen atmosphere (20% (v/v H ₂ /N ₂ )), 200-250° C. for 4 hours. The solidified manganese oxide was pulverized to a powder form of 20 nm or more and 100 nm or less using a mortar. Finally, the powder was heat treated at 500° C. for 2 hours.

Example 3- Pd-Mn _x O _y Preparation of nanorod electrocatalyst

Manganese nitrate (Mn(NO ₃ ) ₂ ) (Alfa Aesar) as a manganese precursor, palladium(II) acetate (Sigma Alderich) as a transition metal compound, and glycine (C ₂ H ₅ NO ₂ ) (Alfa Aesar) as a fuel ), citric acid (Alfa Aesar) was used as a complexing agent and a reducing agent. After dissolving 800 mg of manganese nitrate in distilled water to prepare an aqueous precursor solution, 1,600 g of glycine was added under stirring using a magnetic stirrer. This solution was named MG solution. Then, a 0.2M palladium (II) acetate solution was added to the MG solution at 10% by weight, and then 1,200 mg of citric acid was added, until 60% to 70% of the solvent was evaporated until a gel appeared. Stirring while maintaining ℃. Then, in order to remove volatile impurities from the gelled manganese oxide and solidify, it was heated in a hydrogen atmosphere (20% (v/v H ₂ /N ₂ )), 200-250° C. for 4 hours. The solidified manganese oxide was pulverized to a powder form of 20 nm or more and 100 nm or less using a mortar. Finally, the powder was heat treated at 500° C. for 2 hours.

Comparative Example 1 - Mn _x O _y Preparation of nanorod electrocatalyst

Manganese nitrate (Mn(NO ₃ ) ₂ ) (Alfa Aesar) was used as a manganese precursor, glycine (C ₂ H ₅ NO ₂ ) (Alfa Aesar) as a fuel, and citric acid (Alfa Aesar) as a complexing agent and reducing agent. . After dissolving 800 mg of manganese nitrate in distilled water to prepare an aqueous precursor solution, 1,600 g of glycine was added under stirring using a magnetic stirrer. This solution was named MG solution. Then, after adding 1,200 mg of citric acid, the mixture was stirred while maintaining 80° C. until 60% to 70% of the solvent was evaporated and a gel appeared. Then, in order to remove volatile impurities from the gelled manganese oxide and solidify, it was heated in a hydrogen atmosphere (20% (v/v H ₂ /N ₂ )), 200-250° C. for 4 hours. The solidified manganese oxide was pulverized to a powder form of 20 nm or more and 100 nm or less using a mortar. Finally, the powder was heat treated at 500° C. for 2 hours.

Comparative Example 2 - Pt-C catalyst

A commercially available Pt-C catalyst (Alfa Aesar) was used without a separate manufacturing process.

Comparative Example 3 -Au

Commercially available Au (Alfa Aesar) was used without a separate manufacturing process.

Evaluation of the electrochemical properties of catalysts

Electrocatalyst Measurement - Rotating Disk Electrode (RDE) Measurement

Rotating disk electrode (RDE) measurements were performed on a Bonatec electrochemical workstation using a conventional three-electrode system. A glass carbon disk electrode with a diameter of 5 mm was used as the working electrode. Pt wire and Hg/HgO electrode were used as counter electrode and reference electrode, respectively. To prepare a working electrode, 5 mg of the prepared catalyst and 5 mg of carbon powder were mixed with 4 ml of ethanol and 80 ml of a 5 wt% Nafion solution (Dupont). After making well-sprayed ink through micro-digestion, 10 ml of ink was pipetted onto a glass carbon electrode and evaporated at room temperature for 0.5 hour to form a catalyst film. The catalytic load applied to the free carbon disk electrode was 0.063 mg m ⁻² . The LSV was scanned from 0.1V to -0.8V and recorded at a scan rate of 5mVs ^-1 on a disk electrode obtained from BASI with part number EF-1100F. Before the measurement, the solution was contained with oxygen (O ₂ ) and an O ₂ atmosphere was maintained during the measurement. For comparison, a commercially available 20 wt% Pt-C catalyst (Sigma Aldrich.) was tested according to the same procedure. After the electrochemical test, it was calibrated with a RHE (Reversible Hydrogen Electrode) scale. All experiments were conducted at room temperature.

The general XRD patterns of the prepared Mn _x O _y and Au-Mn _x O _y nanorod electrode catalysts are shown in FIG. 1 . The diffraction peaks correspond to the (110), (101), (200), (111), (210), (211), (220), (310), (221) and (301) crystal planes of MnO ₂ ( JCPDS No. 24-0735, square, I4/m, a=b=0.78 Å, c=2.86 Å). In addition, it can be seen that the diffraction peak of Mn _x O _y is weak and broad, indicating that the crystallinity of Mn _x O _y is weak. On the other hand, in the case of Au-Mn _x O _y nanorod electrocatalyst, additional (111), (200) and (220) peaks were observed in Au (JCPDS No. 65-2870). The sharp diffraction peak indicates high crystallinity of Au. Therefore, the results of this experiment confirm that the Au-Mn _x O _y complex is generated.

The XPS spectrum is used to analyze to find the oxidation state of the metal center according to the type of bonding interaction in the Au-Mn _x O _y nanorod electrocatalyst. The irradiation spectrum of FIG. 4a confirms the presence of Mn, Au and O without impurities. The Mn 2p3/2 peak as shown in Fig. 4b was cantered at 642.3 eV. On the other hand, the Mn 2p1/2 peak was observed with a spin energy separation of 654.1 eV to 11.8 eV, indicating that the Mn atom of the Au-Mn _x O _y nanocatalyst is in the Mn 2p form.

As shown in Fig. 4c, the O1s peak can be resolved into three peaks corresponding to Mn-O-Mn (529.9 eV), Mn-O-H (531.5 eV) and H-O-H (532.9 eV), respectively.

As shown in Fig. 4d, XPS spectra with two main peaks at 87.95 and 84.27 eV correspond to Au 4f5/2 and Au 4f7/2, respectively, indicating that gold is a metal in Au-Mn _x O _y nanorod electrocatalyst. It means a metallic state.

3 shows Mn_xO_y and Au-Mn_xO_yFESEM, Figure 5 is Pt-Mn_xO_y, Pd-Mn_xO_yand Au-Mn_xO_yTEM and HR-TEM are shown. According to Figures 3 and 5, Pt-Mn_xO_y, Pd-Mn_xO_y, Au-Mn_xO_yand Mn_xO_yIt can be seen that has a rod-shaped shape. This is called a nanorod. The nanorods of the present invention had a smooth surface and were measured to have a length of 2 to 10 mm and a width of 30 to 100 nm.

7 shows LSV data taken at 0.1M KOH. The KOH solution was purged with oxygen gas for 2 hours to make an O ₂ -saturated KOH solution, and the rotation speed of the rotating disk electrode (RDE) was set to 1600 rpm to Mn _x O _y , 10 wt% Au-Mn _x O _y , LSV of 20 wt% Pt-C, 10 wt% Pt-Mn _x O _y and 10 wt% Pd-Mn _x O _y, is measured. The onset potential of 10 wt% Au-Mn _x O _y , 10 wt % Pt-Mn _x O _y and 10 wt % Pd-Mn _x O _y (potential at a current density of 100 mA ^-2 ) was higher than that of the Mn _x O _y catalyst. more positive In addition, the limiting current density (4.9 mA ^-2 ) of the 10 wt% Au-Mn _x O _y , 10 wt % Pt-Mn _x O _y and 10 wt % Pd-Mn _x O _y catalysts is also much higher than that of Mn _x O _y . . The electrochemical catalytic activity of the tested catalyst in terms of initiation potential is 10 wt% Pt-Mn _x O _y > 10 wt % Pd-Mn _x O _y > 20 wt % Pt-C > 10 wt % Au-Mn _x O _y > Follow the order of Mn _x O _y . 10 wt % Pt-Mn _x O _y , 10 wt % Pd-Mn _x O _y and The excellent catalytic activity of 10 wt% Au-Mn _x O _y is due to the synergistic effect of Mn _x O _y with the transition metal elements of Pt, Pd and Au, respectively.

Therefore, the Mn _x O _y -based electrocatalyst decorated with a transition metal according to the present invention can exhibit comparable or improved electrocatalytic activity to commercially available Pt-C, as shown in FIG. 7 .

Accordingly, the present invention can prevent the separation of the support and the catalyst generated in the electrode as described above, so it has high stability and high catalytic efficiency, simplifies the manufacturing process of the electrode catalyst through the solution combustion route, and reduces the amount of platinum used. can be reduced

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (17)

In the method for manufacturing a nanorod electrode catalyst,
preparing a manganese precursor aqueous solution by dissolving the manganese precursor in distilled water;
adding fuel to the aqueous manganese precursor solution under stirring;
generating a manganese oxide decorated with monodispersed transition metal nanoparticles (NPs) by adding a transition metal compound solution and a complexing agent to the aqueous manganese precursor solution;
stirring to gel the manganese oxide;
heating to remove volatile impurities from the gelled manganese oxide and solidify;
pulverizing the solidified manganese oxide to obtain a powdery mixture; and
calcinating the mixture to remove volatile impurities and increase crystallinity;
A method for producing a nanorod electrode catalyst for a fuel cell, characterized in that it has a heterostructure in which the monodisperse transition metal nanoparticles are decorated with the monodisperse transition metal nanoparticles and has a heterostructure in which oxygen deficiency is present and is represented by the following Chemical Formula 1:
[Formula 1] A-Mn _x O _y
In Formula 1, A is gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), silver (Ag), nickel (Ni), iron (Fe), from the group consisting of cobalt (Co) It may include at least one selected element, wherein x is 1≤x≤3, and y is 1≤y≤7. The method according to claim 1, wherein the manganese precursor aqueous solution is at least one selected from among manganese nitrate, manganese acetate, and manganese sulfate. According to claim 1, wherein the fuel (fuel) is urea (CH ₄ N ₂ O), glycine (C ₂ H ₅ NO ₂ ), glucose (C ₆ H ₁₂ O ₆ ), sucrose (C ₁₂ H ₂₂ O ₁₁ ) , carbohydrazide (CH ₆ N ₄ O), oxalidahydrazide (C ₂ H ₆ N ₄ O ₂ ), hexamethylenetetramine (C ₆ H ₁₂ N ₄ ) and acetylacetone (C ₅ H ₈ O ₂ ) ) A method of manufacturing a nanorod electrode catalyst for a fuel cell, characterized in that at least one selected from the group consisting of. According to claim 1, wherein the complexing agent (complexing agent) is citric acid (citraic acid) and tannic acid (tannic acid) may be at least one selected from the fuel cell nano, characterized in that added to the cationic metal in a weight ratio of 2:1 A method for manufacturing a rod electrocatalyst. The method according to claim 1 or 3, wherein the aqueous solution of the manganese precursor is mixed with the fuel at a 2:1 weight ratio at room temperature and stirred. The method according to claim 1, wherein 10 to 20 wt% of the transition metal compound solution is added to the manganese precursor aqueous solution. The method according to claim 1, wherein the transition metal compound is at least one selected from transition metal nitrate, transition metal acetate, and transition metal halide. The method according to claim 1, wherein Mn _x O _y in Formula 1 is MnO, Mn ₃ O ₄ , Mn ₂ O ₃ , α-MnO ₂ , β-MnO ₂ , γ-MnO ₂ , δ-MnO ₂ , MnO ₃ , Mn ₂ O ₇ , Mn ₂ O ₄ A method of manufacturing a nanorod electrode catalyst for a fuel cell, characterized in that any one. The fuel according to claim 1, wherein in the step of stirring to gel the manganese oxide, stirring is performed at 50 to 90°C until 60% to 70% of the solvent is evaporated to form a gel. A method for manufacturing a nanorod electrocatalyst for a battery. The method of claim 1 , wherein the heating temperature is increased to 200 to 250° C. for 2 to 5 hours. The method according to claim 1, wherein the particle size of the powder mixture is 20 nm or more and 100 nm or less. The method of claim 1, wherein the step of calcinating the mixture to remove volatile impurities and increase crystallinity is performed at 500 to 800° C. for 1 to 4 hours. 11. The method according to any one of claims 1 to 10, wherein the step of heating to remove volatile impurities from the gelled manganese oxide and solidify is performed under a mixed gas of hydrogen (H ₂ ) gas and inert gas. A method for manufacturing a nanorod electrode catalyst for a fuel cell. The method of claim 13, wherein the inert gas is nitrogen (N ₂ ) gas. 14. The method of claim 13, wherein the hydrogen gas (H ₂ ) in the mixed gas has an amount of 10 to 40 vol%. A fuel cell nanorod, characterized in that the manganese oxide prepared according to any one of claims 1 to 15 and decorated with transition metal nanoparticles has a heterostructure in which oxygen deficiency exists and is represented by the following Chemical Formula 1 Electrocatalyst:
[Formula 1] A-Mn _x O _y
In Formula 1, A is gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), silver (Ag), nickel (Ni), iron (Fe), from the group consisting of cobalt (Co) It may include at least one selected element, wherein x is 1≤x≤3, and y is 1≤y≤7. The method according to claim 16, wherein Mn _x O _y in Formula 1 is MnO, Mn ₃ O ₄ , Mn ₂ O ₃ , α-MnO ₂ , β-MnO ₂ , γ-MnO ₂ , δ-MnO ₂ , MnO ₃ , Mn ₂ O ₇ , Mn ₂ O ₄ Nanorod electrode catalyst for a fuel cell, characterized in that any one.

Images