KR20210151282A - Solid oxide catalyst for electrolyzation having double perovskite structure, and solid oxide electrolyzer cell, and metal air battery having the same - Google Patents

Abstract

The present invention provides a catalyst for aqueous electrolysis of solid oxide having excellent oxygen evolution reaction. The catalyst for aqueous electrolysis of solid oxide according to an embodiment of the present invention is a catalyst for aqueous electrolysis of solid oxide contained in an electrode for oxygen evolution reaction, and the catalyst for aqueous electrolysis of solid oxide includes a PrBa_(0.5)Sr_(0.5)Co_(2 - x)Fe_xO_(5 + δ) compound (herein, δ, as a positive number of 1 or less, is a value that makes the compound electrically neutral), and x ranges from 0.4 or more to 0.5 or less, to increase the oxygen generating activity of the catalyst for aqueous electrolysis of solid oxide and reduce overvoltage.

Description

Solid oxide catalyst for electrolyzation having double perovskite structure, and solid oxide electrolyzer cell, and metal air battery having double-layer perovskite material the same}

The present invention relates to a catalyst for solid oxide water-based electrolysis composed of a double-layer perovskite material, a solid oxide water electrolysis cell including the same, and a method for manufacturing the same.

Recently, research on a technology for obtaining energy using hydrogen gas is attracting attention. Conventional energy sources such as coal or petroleum contain carbon, whereas hydrogen gas does not contain carbon at all and is mostly converted to water. can cause Therefore, hydrogen gas is considered as the most environmentally friendly and ideal energy source. In order to use hydrogen as an energy source, it is necessary to obtain hydrogen gas from water, hydrocarbon, or the like. In order to obtain hydrogen gas, hydrogen gas may be generated through a steam reforming pyrolysis gasification process using hydrocarbon-based substances such as natural gas, coal, and petroleum. However, since these hydrocarbon-based materials also generate unwanted by-products, there is a risk of polluting the environment.

Another method for obtaining hydrogen gas is to produce hydrogen by electrolysis, which applies energy to water. Water is a clean resource that exists everywhere, and since water can be decomposed into hydrogen gas and oxygen gas or the reverse reaction is possible, it has the advantage of high regeneration potential, so water can be treated as an ideal hydrogen gas raw material. In addition, since the hydrogen production technology according to the electrolysis of water can recycle waste heat, it is in the spotlight as a hydrogen gas production technology.

Since the electrolysis method of water according to the current technology uses heat at a high temperature of 800° C. or higher, it is limited to the temperature level of waste heat emitted from nuclear power plants. In addition, in such a high-temperature environment, nickel, which is an electrode material in contact with hydrogen, may be coarsened at a high temperature and deteriorate. In addition, during water decomposition, oxygen ions are oxidized to generate oxygen gas, while hydrogen ions are reduced to generate hydrogen gas. A commonly used catalyst for water decomposition has a problem in that when one of the hydrogen evolution reaction (HER) performance and the oxygen evolution reaction (OER) performance is good, the other performance is deteriorated. Therefore, it is required to develop a catalyst for aqueous electrolysis with excellent oxygen evolution reaction.

Korean Patent Publication No. 10-2018-0088654

It is an object of the present invention to provide a catalyst for solid oxide aqueous electrolysis composed of a double-layer perovskite material having excellent oxygen evolution reaction.

It is an object of the present invention to provide a solid oxide aqueous electrolysis cell including the catalyst for solid oxide aqueous electrolysis.

It is an object of the present invention to provide a method for manufacturing a solid oxide aqueous electrolysis cell including the catalyst for solid oxide aqueous electrolysis.

However, these tasks are exemplary, and the technical spirit of the present invention is not limited thereto.

The catalyst for aqueous solid oxide electrolysis according to the technical idea of the present invention for achieving the above technical problem is a catalyst for solid oxide aqueous electrolysis included in an electrode for oxygen evolution reaction, wherein the catalyst for solid oxide aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral), increasing the oxygen evolution activity of the solid oxide-aqueous electrolyte for the catalyst body and to reduce overvoltage, x may be in the range of 0.4 or more to 0.5 or less.

In an embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis may exhibit an overvoltage in the range of 0.29V to 0.31V at a current density of ^{10 mA cm -1 .}

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis may exhibit a Tafel slope in the range of 69 mV/dec to 79 mv/dec.

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis, 34 mF cm ^-2 to 43 mF cm ^{-2 It} may exhibit a double-layer capacitance in the range.

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis, PrBa _0.5 Sr _0.5 Co _1.6 Fe _0.4 O _{5 + δ} compound, PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 55} Fe _{0 . 45} O _{5 +δ} compound, or PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _5+δ compound.

A solid oxide water electrolysis cell according to the technical idea of the present invention for achieving the above technical object includes: a cathode for discharging hydrogen gas formed by decomposition of water; an anode disposed to face the cathode and discharging oxygen gas formed by decomposition of the water; and an electrolyte disposed between the anode and the cathode, a solid oxide water electrolysis cell for generating hydrogen and oxygen, wherein at least one of the anode and the cathode comprises a catalyst for solid oxide aqueous electrolysis, the solid The catalyst for oxide aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral), increasing the oxygen evolution activity of the solid oxide-aqueous electrolyte for the catalyst body and to reduce overvoltage, x may be in the range of 0.4 or more to 0.5 or less.

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis may exhibit an overvoltage in the range of 0.29V to 0.31V at a current density of ^{10 mA cm -1 , and 69 mV/dec to 79 mv/} It can exhibit a Tafel slope in the range of dec , and can exhibit a double layer capacitance ranging from ^{34 mF cm -2} to 43 mF cm ^{-2 .}

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis, PrBa _0.5 Sr _0.5 Co _1.6 Fe _0.4 O _{5 + δ} compound, PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 55} Fe _{0 . 45} O _{5 +δ} compound, or PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _5+δ compound.

Metal-air battery according to the technical idea of the present invention for achieving the above technical problem, a cathode; an anode disposed to face the cathode; and an electrolyte disposed between the cathode and the anode, wherein the cathode includes a catalyst for solid oxide aqueous electrolysis, and the solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral), increasing the oxygen evolution activity of the solid oxide-aqueous electrolyte for the catalyst body and to reduce overvoltage, x may be in the range of 0.4 or more to 0.5 or less.

In one embodiment of the present invention, the solid oxide catalyst for aqueous electrolysis exhibits an overvoltage in the range of 0.29V to 0.31V at a current density of ^{10 mA cm -1 , and in the range of 69 mV/dec to 79 mv/dec} represents the Tafel slope of , and may exhibit a double layer capacitance in the range of ^{34 mF cm -2} to 43 mF cm ^{-2 .}

In one embodiment of the present invention, the solid oxide catalyst for the water-based electrolytic _{body, PrBa 0 .5 Sr 0.5 Co 1.6} Fe 0.4 O 5 + δ compound, PrBa _{0. 5} Sr _{0 . 5} Co _{1 . 55} Fe _{0 . 45} O _{5 +δ} compound, or PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _5+δ compound.

The catalyst for solid oxide aqueous electrolysis according to the technical concept of the present invention is PrBa _0.5 Sr _0.5 Co ₂ O _5+d by replacing cobalt with iron PrBa _{0 . 5} Sr _{0 . 5} Co _{2 -} is implemented by forming an _x Fe _x O _{5 + δ} compound. When the iron content of the compound, x, was in the range of 0.4 or more to 0.5 or less, the oxygen evolution activity was large, the Tafel slope was small, and the double layer capacitance was large. Accordingly, when the catalyst for solid oxide aqueous electrolysis composed of the compound having the iron content is included, it is possible to provide a solid oxide aqueous electrolysis cell and a metal-air battery having excellent oxygen evolution reaction.

The above-described effects of the present invention have been described by way of example, and the scope of the present invention is not limited by these effects.

1 is a diagram schematically illustrating a solid oxide water electrolysis cell including a catalyst for solid oxide water-based electrolysis according to an embodiment of the present invention.
2 is a diagram schematically illustrating a metal-air battery including a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.
3 is a schematic diagram illustrating a double-layered perovskite crystal structure constituting a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.
4 is a schematic diagram illustrating a case in which some atoms are substituted in the double-layered perovskite crystal structure constituting the catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.
5 is a flowchart illustrating a method for preparing a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.
6 is an X-ray diffraction graph of a catalyst for aqueous electrolysis of a solid oxide formed by using the method for preparing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.
7 is a graph showing the oxygen generation activity of the catalyst for aqueous electrolysis of a solid oxide formed by using the method for preparing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.
8 is a graph showing the overvoltage at a current density ^{of 10 mA cm −1} of the catalyst for aqueous electrolyte solution for solid oxide formed by using the method for preparing the catalyst for aqueous electrolysis of solid oxide according to an embodiment of the present invention.
9 is a graph showing the relationship between overvoltage and current density of a catalyst for aqueous electrolysis of a solid oxide formed by using the method for manufacturing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.
10 is a graph showing the relationship between the current density and the scan speed of the solid oxide catalyst for aqueous electrolysis formed by using the method for preparing the catalyst for aqueous solid oxide electrolysis according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more completely explain the technical idea of the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, The scope of the technical idea is not limited to the following examples. Rather, these embodiments are provided to more fully and complete the present disclosure, and to fully convey the technical spirit of the present invention to those skilled in the art. In this specification, the same reference numerals refer to the same elements throughout. Furthermore, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

Currently, as alkaline water electrolysis systems for hydrogen production attract attention, efficient electrode catalysts are also being widely studied. When driving such a water electrolysis system, electrochemically, the following oxygen evolution reaction (OER) is essentially utilized.

<Oxygen evolution reaction>

4OH ^- -> O ₂ + 2H ₂ O + 4e ^-

The oxygen evolution reaction rate is slow due to the high overvoltage in the water electrolysis system, and the bottleneck in the water electrolysis system depends on the slow oxygen evolution reaction rate, so it is necessary to develop a catalyst for an efficient oxygen evolution reaction. There is a need. In order to replace expensive platinum-based catalysts used as conventional electrode catalysts, noble metal-based catalysts such as ruthenium (Ru) or iridium (Ir) have been researched and developed. The technical idea of the present invention is to provide a catalyst for solid oxide aqueous electrolysis based on perovskite oxide as a catalyst for oxygen evolution reaction.

1 is a diagram schematically illustrating a solid oxide water electrolysis cell 100 including a catalyst for solid oxide water-based electrolysis according to an embodiment of the present invention.

Referring to FIG. 1 , the solid oxide water electrolysis cell 100 has an anode 110 , a cathode 120 disposed to face the anode 110 , and oxygen ions disposed between the anode 110 and the cathode 120 . and electrolyte 130 which is a conductive solid oxide. The cathode 120 may be referred to as a hydrogen electrode because it is in contact with hydrogen gas, and the anode 110 may be referred to as an oxygen electrode because it is in contact with the oxygen gas.

The electrochemical reaction of the solid oxide water electrolysis cell 100 is a cathode reaction in which water (H ₂ O) of the cathode 120 is changed to hydrogen gas (H ₂ ) and oxygen ions (O ^{2 - ) as shown in the following reaction formula} And the oxygen ions that have moved through the electrolyte 130 are _{converted into oxygen gas (O 2} ) by an anode reaction. This reaction is contrary to the reaction principle of a conventional fuel cell.

<reaction formula>

Cathodic reaction: H ₂ O + 2e ^- -> O ² - + H ₂

Anode reaction: O ^2- -> 1/2 O ₂ + 2e ^-

When power is applied from the external power source 140 to the solid oxide water electrolysis cell 100 , electrons are provided to the solid oxide water electrolysis cell 100 from the external power source 140 . The electrons react with water provided to the cathode 120 to generate hydrogen gas and oxygen ions. The hydrogen gas is discharged to the outside, and the oxygen ions pass through the electrolyte 130 and move to the anode 110 . The oxygen ions moved to the anode 110 lose electrons, are converted into oxygen gas, and are discharged to the outside. The electrons flow to the external power source 140 . Through this electron movement, the solid oxide water electrolysis cell 100 may electrolyze water to form hydrogen gas at the cathode 120 and oxygen gas at the anode 110 .

The anode 110 may be configured to include a catalyst for solid oxide aqueous electrolysis made of a double-layer perovskite material according to the technical spirit of the present invention.

The cathode 120 is not particularly limited and a known cathode may be used. The cathode 120 may include the same material as the anode 210 of the above-described solid oxide fuel cell 200 or may have the same structure. In addition, the case in which the cathode 120 is configured to include a catalyst for aqueous solid oxide electrolysis according to the technical spirit of the present invention is also included in the technical spirit of the present invention.

The electrolyte 130 is not particularly limited as long as it can be generally used in the art. The electrolyte 130 may include the same material or have the same structure as the electrolyte 230 of the solid oxide fuel cell 200 described above.

Since the solid oxide water electrolysis cell 100 can be manufactured using a conventional method known in various documents in the art, a detailed description thereof will be omitted herein. In addition, the solid oxide water electrolysis cell 100 may be applied to various structures such as a cylindrical stack, a flat tubular stack, and a planar type stack. The solid oxide water electrolysis cell 100 may be in the form of a stack of unit cells. For example, unit cells composed of an anode 110 , a cathode 120 , and an electrolyte 130 are stacked in series, and a separator electrically connecting them is interposed between the unit cells. A stack may be obtained.

2 is a diagram schematically illustrating a metal-air battery 200 including a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.

Referring to FIG. 2 , the metal-air battery 200 includes an anode 210 , a cathode 220 , and an electrolyte 230 positioned between the anode 210 and the cathode 220 . The cathode 220 may further include a current collector 240 and a catalyst body 250 .

The metal-air battery 200 generates electric power by using a reaction between metal and oxygen. The greatest advantage of the metal-air battery 200 is that it uses oxygen, which is infinitely present in nature, as an active material, has a very high theoretical energy density compared to other secondary batteries, and also has an affinity-friendly characteristic. In addition, since the metal-air battery 200 does not contain a chemical oxidizing agent therein, there is no risk of explosion or fire, and the weight can be greatly reduced. In addition, compared to a fuel cell using hydrogen or alcohol, it is very economical, has excellent stability, and has excellent operating ability at a low temperature.

The anode 210 may include a material that loses electrons during discharge to become a cation, for example, may include a metal, and may include, for example, lithium, zinc, magnesium, aluminum, and calcium. In particular, lithium has a theoretical energy density of 11,140 Wh/kg, which is almost similar to gasoline of 13,000 Wh/kg. For reference, aluminum has a theoretical energy density of 8130 Wh/kg, calcium 4180 Wh/kg, and zinc 1350 Wh/kg. In addition, the anode 210 may be configured using an electrode material according to the technical idea of the present invention.

The cathode 220 is configured to use oxygen in the air, and may collect the oxygen. The cathode 220 may be configured to include a catalyst for solid oxide aqueous electrolysis made of a double-layer perovskite material according to the technical spirit of the present invention.

Since the metal-air battery 200 uses oxygen in the air for the cathode 220 , theoretically, the weight of the cathode 220 can be reduced to zero or drastically. Therefore, since the weight of the anode 210 can be increased by reducing the weight of the cathode 220, the weight ratio of the anode 210 to the total weight of the metal-air battery 200 is increased, resulting in the battery It can provide high energy density per unit weight.

The electrolyte 230 is positioned between the anode 210 and the cathode 220 and may include an electrolyte material. The electrolyte 230 may include, for example, a sodium hydroxide (NaOH) solution or a calcium hydroxide (KOH) solution. In addition, the electrolyte 230 may be composed of a solid medium.

Hereinafter, power generation in the metal-air battery 200 will be described. In the anode 210 and the cathode 220, a discharging reaction and a charging reaction may be performed. Discharge reactions at the anode 210 and the cathode 220 are as follows. The charging reaction causes the following reactions to go in the opposite direction. In the following reaction formula, “M” may be a metal as a material constituting the anode 210 .

<reaction formula>

Cathodic reaction: 2( M ⁺ + e ^- ) + O ₂ -> M ₂ O ₂

Anode reaction: M -> M ⁺ + e ^-

The positive ions 270 formed in the anode 210 by this discharge reaction pass through the electrolyte 230 and are directed to the cathode 220 . At this time, the electrons lost by the positive ions pass through the load 290 through a separate conducting wire, and as a result, power is supplied to the load 290 .

Oxygen 280 is provided to the cathode 220 from the outside, and the cation 270 reacts with the oxygen 280 at the cathode 220 to form an oxide. At this time, electrons passing through the load 290 are provided to the cathode 220 to form the oxide together.

On the other hand, during charging, the oxide is decomposed and the cations acquire electrons and return to the anode 210 from the cathode 220 through the electrolyte 230 .

Hereinafter, a catalyst for solid oxide aqueous electrolysis, which is a component constituting the anode 110 of the solid oxide water electrolysis cell 100 , will be described in detail. The solid oxide catalyst for aqueous electrolysis may be applied to the cathode 220 of the metal-air battery 200 and. The catalyst for solid oxide aqueous electrolysis according to the technical spirit of the present invention may have a perovskite structure.

3 is a schematic diagram illustrating a double-layered perovskite crystal structure constituting a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.

Referring to FIG. 3 , the catalyst for solid oxide aqueous electrolysis may be composed of a perovskite crystal structure material, for example, a single perovskite crystal structure material or a double-layer perovskite crystal structure material. can

Hereinafter, the perovskite crystal structure material will be described.

A single perovskite crystal structure represented by ABO ₃ is an element with a large ionic radius, such as rare earth elements, alkaline rare earths, and alkalines, at the A-site, which is a corner position of a cubic lattice. are located, and have a 12 coordination number (CN, Coordination Number) by oxygen ions. Transition metals with small atomic radii such as Co and Fe are located at the B-site, which is the body center position of the cubic lattice, and an octahedron (6 coordination number) is formed by oxygen ions. Finally, oxygen ions are located at each face center of the cubic lattice.

In this single perovskite crystal structure, structural displacement generally occurs when another material is substituted in the A-site, and its maximum is mainly centered on the element located in the B-site. Structural transformation occurs in the octahedron of _{BO 6} composed of adjacent oxygen ions (6).

For example, when reducing in a hydrogen atmosphere, a single perovskite structure is changed to a double-layered perovskite structure. With such a bilayer perovskite structure, the movement of oxygen ions can be accelerated and thermal and chemical stability can be improved.

As shown in FIG. 3 , the double-layer perovskite crystal structure is a crystal lattice structure in which two or more elements are regularly arranged at the A-site, and may have a chemical formula of _{AA′B 2} O _{5 +δ} . Such a double-layered perovskite crystal structure material has oxygen vacancy clusters to facilitate the movement of ions, thereby providing improved ionic conductivity to the cathode. In the present specification, the aligned double perovskite refers to a crystal lattice structure in which A-site or B-site ions are substituted with two or more elements in general unaligned simple perovskite in the form of _{ABO 3 .}

4 is a schematic diagram illustrating a case in which some atoms are substituted in the double-layered perovskite crystal structure constituting the catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.

As shown in FIG. 4 , the double-layer perovskite structure is a crystal lattice structure in which two or more elements are regularly arranged at the A-site, and may have a chemical formula of _{AA'B 2} O _{5 +δ.} Specifically, in a lanthanide compound having a double-layered perovskite structure, _{a stacking permutation of [BO 2} ]-[AO]-[BO ₂ ]-[A'O] may be repeated along the c-axis. For example, B may be cobalt (Co), A may be a lanthanide group including praseodymium (Pr), and A' may be barium (Ba). In addition, a portion of the barium may be substituted with strontium (Sr), and a portion of the cobalt may be substituted with iron (Fe). When this substitution occurs, the bilayer perovskite structure may _{have the formula AA'B 2 - x} B' _x O _{5 +δ} , for example PrBa _{0 . 5} Sr _{0 . 5} Co _{2 -} may have the formula of _x Fe _x O _{5 + δ.}

The catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention may include a compound of Formula 1 below.

<Formula 1>

PrBa _{0 . 5} Sr _{0 . 5} Co _{2 - x} Fe _x O _{5 +δ}

In Formula 1, δ is a positive number of 1 or less, and is a value that renders the compound of Formula 1 electrically neutral. The δ represents interstitial oxygen in the following double-layer perovskite structure, and the value of δ may be determined according to a specific crystal structure. In addition, x may be in the range of 0.4 or more to 0.5 or less so as to increase the oxygen generating activity of the solid oxide aqueous electrolysis catalyst and reduce overvoltage.

The solid oxide catalyst for aqueous electrolysis may exhibit an overvoltage in the range of 0.29V to 0.31V at a current density of ^{10 mA cm -1 .} The solid oxide catalyst for aqueous electrolysis may exhibit a Tafel slope in the range of 69 mV/dec to 79 mv/dec. The solid oxide catalyst for aqueous electrolysis may exhibit a double-layer capacitance in the range of ^{34 mF cm -2} to 43 mF cm ^-2.

_{PrBa 0} of Formula 1 above _{. 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound is, for example, PrBa ₀ in the formula _{(1). 5} Sr _{0 . 5} Co _{2 - x} Fe _x O _{5 +δ} compound is PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 6} Fe _{0 . 4} O _{5 +δ} compound, PrBa _0.5 Sr _0.5 Co _1.55 Fe _0.45 O _5+δ compound, or PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 5} Fe _{0 . 5} O _{5 +δ} compounds.

The solid oxide catalyst for aqueous electrolysis may be prepared by the following method. As an example of the solid oxide catalyst for aqueous electrolysis, the compound of Formula 2 is specifically PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 5} Fe _{0 . A} method for preparing a catalyst for solid oxide aqueous electrolysis including a 5 O _{5 +δ compound will be described.} However, the technical spirit of the present invention is not limited thereto.

5 is a flowchart illustrating a method for preparing a catalyst for solid oxide aqueous electrolysis according to an embodiment of the present invention.

Referring to FIG. 5 , the method for preparing the solid oxide catalyst for aqueous electrolysis (S100) includes mixing a plurality of metal precursors to form a mixture (S110), calcining the mixture (S120), the calcined reducing the mixture (S130), and annealing the reduced mixture to form a catalyst body having a perovskite crystal structure material (S140).

A step ( S110 ) of forming a mixture by mixing the plurality of metal precursors is performed. A plurality of metal precursors are mixed to match the composition of the desired perovskite crystal structure material, for example, the PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 O _{5+δ compound.} Such mixing may be performed using a dry method or may be performed using a wet method of mixing metal precursors in a solvent. Examples of the plurality of metal precursors include nitrides, oxides, and halides of each metal component of Pr, Ba, Sr, Co, and Fe constituting the solid oxide aqueous electrolysis catalyst body, but are limited thereto no. In the wet method, water may be used as a solvent, but is not limited thereto. Any one capable of dissolving or mixing the metal precursors may be used without limitation, for example, a lower alcohol having a total carbon number of 5 or less such as methanol, ethanol, 1-propanol, 2-propanol, butanol; acidic solutions such as nitric acid, hydrochloric acid, sulfuric acid, and citric acid; water; organic solvents such as toluene, benzene, acetone, diethyl ether, and ethylene glycol; These may be used alone or in combination. The mixing process may be performed, for example, at a temperature in the range of about 100°C to about 200°C. The mixing process may be performed for about 1 hour to about 12 hours while stirring so that the metal precursors can be sufficiently mixed. After the mixing process, an ultrafine solid may be obtained by a spontaneous combustion process. The mixing process, solvent removal, and addition of additives required therefor are well known as, for example, a glycine-nitrate process or a pechini method, and thus will not be described in detail here.

The step of calcining the mixture (S120), in an air atmosphere, for example, at a temperature in the range of about 800 °C to about 1300 °C, for example, at a temperature in the range of about 900 °C to about 1000 °C, for example, about 950 °C. It may be carried out at a temperature of about 1 hour to about 12 hours.

The step of reducing the calcined mixture (S130), in a reducing gas atmosphere, for example, at a temperature in the range of about 700 ℃ to about 900 ℃, for example, at a temperature of about 800 ℃, about 1 hour to about 12 hours can be performed while The reducing gas may include any kind of gas that reduces the calcined mixture, and may include, for example, hydrogen gas.

The step (S140) of annealing the reduced mixture to form a catalyst body is performed in an oxidizing gas atmosphere, for example, in an air atmosphere or oxygen atmosphere, for example, at a temperature in the range of about 550° C. to about 700° C., for example. For example, at a temperature in the range of about 600° C. to about 650° C., for example, at a temperature of 650° C., it may be carried out for about 1 hour to about 12 hours. The oxidizing gas may include any kind of gas that oxidizes the reduced mixture, and may include, for example, air (a mixed gas of nitrogen and oxygen) or oxygen gas.

Hereinafter, the experimental results of the solid oxide catalyst for aqueous electrolysis formed using the method for preparing the catalyst for aqueous solid oxide electrolysis according to an embodiment of the present invention will be described. PrBa _{0 . 5} Sr _{0 . 5} Co _{2 -} by changing the "x" to 0, 0.25, 0.4, 0.45, 0.50, 0.60,0.75, 1.00, 1.50, and 2.00 in _x Fe _x O _{5 + δ} to form a compound.

6 is an X-ray diffraction graph of a catalyst for aqueous electrolysis of a solid oxide formed by using the method for preparing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.

Referring to FIG. 6 , PrBa _{0 . 5} Sr _{0 . 5} Co _{2 -} it is shown the X- ray diffraction chart after by changing the "x" to form a compound in _x Fe _x O _{5 + δ.} From the peaks shown in the X-ray diffraction graph, "x" is PrBa _{0 in all compounds in the range of 0 to 2. 5} Sr _{0 . 5} Co _{2 -} a compound having the _x Fe _x O _{5 + δ} structure to find out formed.

7 is a graph showing the oxygen generation activity of the catalyst for aqueous electrolysis of a solid oxide formed by using the method for preparing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.

In FIG. 7 , the oxygen generation activity was measured by a rotating ring disk electrode measurement method by loading the solid oxide aqueous electrolyte catalyst on a glossy carbon electrode in 0.1M KOH electrolyte.

Referring to FIG. 7 , when the catalyst for solid oxide aqueous electrolysis includes iron, the amount of current generated under the same voltage is greatly increased. Specifically, the oxygen generating activity was the lowest in the case of the compound not containing iron (PBSC2.00) and the compound not containing cobalt (PBSF2.00). As the iron content in the solid oxide aqueous electrolysis catalyst increased, the oxygen generation activity was increased. _{In particular, PrBa 0} , wherein x is 0.45 _{. 5} Sr _{0 . 5} Co _{1 . 55} Fe _{0 .} The oxygen generation activity of the solid oxide aqueous electrolysis catalyst composed of ₄₅ O _{5 +δ compounds was the highest.} Thereafter, when the iron content was further increased and the x was increased to more than 0.45, the oxygen generating activity was decreased again.

8 is a graph showing the overvoltage at a current density ^{of 10 mA cm −1} of the catalyst for aqueous electrolyte solution for solid oxide formed by using the method for preparing the catalyst for aqueous electrolysis of solid oxide according to an embodiment of the present invention.

Referring to FIG. 8 , as the iron content in the solid oxide aqueous electrolysis catalyst increased, the overvoltage was reduced. When x was 0.45, the overvoltage showed the minimum value. Subsequently, when the iron content was further increased such that x was increased to exceed 0.45, the overvoltage was increased again. For example, when x is 0.4, an overvoltage of about 0.305 V was exhibited, when x was 0.45, an overvoltage of about 0.299 V was exhibited, and when x was 0.5, an overvoltage of about 0.303 V was exhibited. .

9 is a graph showing the relationship between overvoltage and current density of a catalyst for aqueous electrolysis of a solid oxide formed by using the method for manufacturing a catalyst for aqueous electrolysis of a solid oxide according to an embodiment of the present invention.

Referring to FIG. 9 , the slope of the relationship between the overvoltage and the current density is represented by a Tafel slope. As the iron content increased in the solid oxide catalyst for aqueous electrolysis, the Tafel slope was decreased. When x was 0.45, the Tafel slope showed a minimum value. Subsequently, when the content of iron was further increased to increase the x by more than 0.45, the Tafel slope was increased again. For example, when x is 0.4, it exhibited a Tafel slope of about 79 mv/dec, when x is 0.45, it exhibited a Tafel slope of about 69 mv/dec, and when x is 0.5, about It showed a Tafel slope of 70 mv/dec. The smaller the Tafel slope, the faster the oxygen evolution reaction rate. Therefore, it can be seen that the oxygen evolution reaction rate is the fastest when x is 0.45.

10 is a graph showing the relationship between the current density and the scan speed of the solid oxide catalyst for aqueous electrolysis formed by using the method for preparing the catalyst for aqueous solid oxide electrolysis according to an embodiment of the present invention.

Referring to FIG. 10 , the slope of the relationship between the current density and the scan speed is expressed as a double layer capacitance (C _dl ). As the iron content in the solid oxide catalyst for aqueous electrolysis was increased, the double layer capacitance was increased. When x is 0.45, the double layer capacitance exhibited a maximum value. Then, when the content of iron was further increased such that x was increased beyond 0.45, the double layer capacitance decreased again. For example, the case where x is 0.4 is approximately 34.55 mF ^cm-case showed the double layer capacitance of ^2, wherein said x is 0.5 ^- showed the double layer capacitance of the ^two, in the case of the x is 0.45 is approximately 42.23 mF cm It is approximately 41.52 cm mF ^- showed the double layer capacitance of the ^two. The larger the double layer capacitance, the larger the electrochemically active surface area. Therefore, it can be seen that the electrochemically active surface area is the largest when x is 0.45.

From the results of FIGS. 7 to 10, when x is 0.45, the oxygen generation activity is the largest, the overvoltage is the smallest, the Tafel slope is the smallest, and the double layer capacitance is the largest. In this case, the oxygen evolution reaction is the most activity can be seen. In addition, for the target oxygen evolution reaction, PrBa _{0 . 5} Sr _{0 . 5} Co _{2 − x} Fe _x O _{5 +δ} It is preferable that the iron content of the compound x is in the range of 0.4 or more to 0.5 or less.

As described above, the present invention has been described with reference to specific content and some examples, but it is to be noted that these are only descriptions presented as specific examples to help a more general understanding of the present invention. The present invention is not limited to the above-described embodiments, and those of ordinary skill in the art to which the present invention pertains can make various modifications and variations to these embodiments, and these modifications and variations are also within the technical spirit of the present invention. is covered in

Accordingly, the embodiments described above and the claims described below, as well as all equivalents or equivalents of the claims, also fall within the scope of the technical spirit of the present invention.

100: solid oxide water electrolysis cell,
110: anode, 120: cathode,
130: electrolyte, 140: external power source;
200: metal air battery,
210: anode, 220: cathode,
230: electrolyte, 240: current collector;
250: catalyst, 270: cation,
280: oxygen, 290: load,

Claims (11)

As a catalyst for solid oxide aqueous electrolysis included in an electrode for oxygen evolution,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral),
In order to increase the oxygen generating activity of the solid oxide aqueous electrolysis catalyst and reduce overvoltage, the x is in the range of 0.4 or more to 0.5 or less, the solid oxide aqueous electrolyte catalyst body. The method according to claim 1,
The catalyst for aqueous electrolysis of the solid oxide exhibits an overvoltage in the range of 0.29V to 0.31V at a current density of ^{10 mA cm -1 , the catalyst for aqueous electrolysis of a solid oxide.} The method according to claim 1,
The catalyst for aqueous electrolysis of a solid oxide, the catalyst for aqueous electrolysis of a solid oxide, exhibiting a Tafel slope in the range of 69 mV / dec to 79 mv / dec. The method according to claim 1,
The catalyst for aqueous electrolysis of the solid oxide, 34 mF cm ^-2 to 43 mF cm ^{-2 The} catalyst body for aqueous electrolysis of a solid exhibits a double-layer capacitance in the range. The method according to claim 1,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 6} Fe _{0 . 4} O _{5 +δ} compound, PrBa _0.5 Sr _0.5 Co _1.55 Fe _0.45 O _5+δ compound, or PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 5} Fe _{0 . 5} O _{5 + δ} compound, including a solid oxide catalyst for aqueous electrolysis. a cathode for discharging hydrogen gas formed by decomposition of water;
an anode disposed to face the cathode and discharging oxygen gas formed by decomposition of the water; and
A solid oxide water electrolysis cell for generating hydrogen and oxygen comprising an electrolyte disposed between the anode and the cathode;
At least one of the anode and the cathode includes a catalyst for solid oxide aqueous electrolysis,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral),
The solid oxide water electrolysis cell, wherein x is in the range of 0.4 or more to 0.5 or less so as to increase the oxygen generating activity of the solid oxide aqueous electrolysis catalyst and reduce the overvoltage. 7. The method of claim 6,
The solid oxide catalyst for aqueous electrolysis,
exhibits an overvoltage in the range of 0.29V to 0.31V at a current density of 10 mA cm ^{-1 ,}
exhibits a Tafel slope in the range of 69 mV/dec to 79 mv/dec,
A solid oxide water electrolysis cell exhibiting a double layer capacitance ranging from 34 mF cm ⁻² to 43 mF cm ^{−2 .} 7. The method of claim 6,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 6} Fe _{0 . 4} O _{5 +δ} compound, PrBa _0.5 Sr _0.5 Co _1.55 Fe _0.45 O _5+δ compound, or PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 5} Fe _{0 . A} solid oxide water electrolysis cell comprising a 5 O _{5 +δ compound.} cathode;
an anode disposed to face the cathode; and
an electrolyte disposed between the cathode and the anode;
The cathode includes a catalyst for solid oxide aqueous electrolysis,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5 Co 2 - x Fe x O} 5 + δ compound includes (where δ is a positive number less than 1, a value that the compound is electrically neutral),
In order to increase the oxygen generating activity of the solid oxide aqueous electrolysis catalyst and reduce overvoltage, the x is in the range of 0.4 or more to 0.5 or less, a metal-air battery. 10. The method of claim 9,
The solid oxide catalyst for aqueous electrolysis,
exhibits an overvoltage in the range of 0.29V to 0.31V at a current density of 10 mA cm ^{-1 ,}
exhibits a Tafel slope in the range of 69 mV/dec to 79 mv/dec,
A metal-air battery, exhibiting a double-layer capacitance in the range of 34 mF cm ^-2 to 43 mF cm ^-2. 10. The method of claim 9,
The solid oxide catalyst for aqueous electrolysis is PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 6} Fe _{0 . 4} O _{5 +δ} compound, PrBa _0.5 Sr _0.5 Co _1.55 Fe _0.45 O _5+δ compound, or PrBa _{0 . 5} Sr _{0 . 5} Co _{1 . 5} Fe _{0 . A} metal-air battery comprising a 5 O _{5 +δ compound.}

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