Layered double hydroxide catalyst, method for producing same, water electrolysis apparatus comprising same, and metal-air secondary battery

Abstract

Disclosed herein is a layered double hydroxide catalyst having catalytic activity for an oxygen evolution reaction (OER) or an oxygen reduction reaction (ORR). The layered double hydroxide catalyst has a chemical structure represented by chemical formula 1. [Chemical formula 1] [M1 1-(a+b)M2 aY3+ b(OH)2][An-](a+b) / n·cH2O. In chemical formula 1, M1 is a first transition metal positive electrode having an oxidation state of +2, M2 is a second transition metal positive electrode having an oxidation state of +3, A is an interlayer negative electrode having an oxidation state of -n, a and b are positive real numbers satisfying the condition "0<a+b< 1", n is an integer of 1 to 5, and c is a positive real number.

Description

Layered metal double-layer hydroxide catalyst, method for producing the same, electrolysis device and metal-air secondary battery comprising the same

[0001] The present invention relates to a layered metal double-layer hydroxide catalyst having catalytic activity for an oxygen evolution reaction or an oxygen reduction reaction, a method for producing the same, a water electrolysis device having the same, and a metal-air secondary battery.

[0002] Due to problems such as the depletion of fossil fuels and environmental pollution, research is being actively conducted on environmentally friendly renewable energy devices that use hydrogen, such as fuel cells, and metal-air secondary batteries that store energy generated from renewable energy devices.

[0003] To produce the above hydrogen in an environmentally friendly manner, water electrolysis devices are widely used, and these water electrolysis devices can produce hydrogen and oxygen from water through an oxygen evolution reaction (OER) that occurs at the anode and a hydrogen evolution reaction (HER) that occurs at the cathode.

[0004] And metal-air secondary batteries can store electrical energy through the oxygen reduction reaction (ORR) that occurs at the air electrode and the metal oxidation reaction that occurs at the metal electrode.

[0005] In the case of water electrolysis devices and metal-air secondary batteries that are currently commercialized or mainly being studied, precious metal-based materials such as iridium and ruthenium have been mainly used as catalysts for the oxygen evolution reaction (OER) or the oxygen reduction reaction (ORR). However, due to the high price of the catalyst, not only has the economic feasibility decreased, but various studies are being conducted on non-precious metal-based catalyst materials to further improve stability.

[0006] Among the non-precious metal-based catalysts, layered metal double-layer hydroxide (LDH) catalysts are less expensive and more abundant than precious metals, and have recently attracted significant attention as OER or ORR catalysts. However, LDH catalysts have the disadvantage of low electrical conductivity, making it difficult to expect high catalytic activity.

[0007] One object of the present invention is to provide a layered metal double layer hydroxide (LDH) catalyst having relatively high electrical conductivity and exhibiting high catalytic activity for an OER reaction or an ORR reaction.

[0008] Another object of the present invention is to provide a method for producing the layered metal bilayer hydroxide catalyst.

[0009] Another object of the present invention is to provide a water electrolysis device that uses the layered metal double layer hydroxide catalyst as a catalyst for the OER reaction.

[0010] Another object of the present invention is to provide a metal-air secondary battery using the layered metal double layer hydroxide catalyst as a catalyst for the ORR reaction.

[0011] A layered metal bilayer hydroxide catalyst according to an embodiment of the present invention is represented by the following chemical formula 1, has a layered bilayer structure, and can have catalytic activity for an oxygen evolution reaction (OER) or an oxygen reduction reaction (ORR).

[0012] [Chemical Formula 1]

[0013] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0014] In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

[0015] In one embodiment, the first transition metal cation is Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn 2+ , Co 2+ , Fe 2+ and Cu 2+ comprising at least one selected from the group consisting of, wherein the second transition metal cation is Fe 3+ , Al 3+ , Cr 3+ , Mn 3+ , Ga 3+ , Co 3+ and Ni 3+ Contains at least one selected from the group consisting of, wherein the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- and H2PO4 - It may include one or more selected from the group consisting of .

[0016] In one embodiment, the yttrium (Y) cation may be present in the lattice in a form that substitutes a portion of the second transition metal cation.

[0017] In one embodiment, the layered metal bilayer hydroxide catalyst comprises six hydroxide ions (OH - ) formed by coordination of the first octahedral structure, each of the second transition metal cations having six hydroxide ions (OH - ) and the second octahedral structure formed by coordination with the yttrium ion and seven hydroxide ions (OH -) may include an icosahedral structure formed by coordination.

[0018] In one embodiment, in the chemical formula 1, a+b may be about 0.2 or more and 0.5 or less, and the molar ratio (a / b) of the second transition metal cation to the yttrium ion may be 20 or more and 150 or less. For example, the molar ratio (a / b) of the second transition metal cation to the yttrium ion may be 33 or more and 105 or less.

[0019] In one embodiment, the layered metal bilayer hydroxide catalyst may have a nanosheet form having a size of 20 to 1000 nm.

[0020] In one embodiment, the layered metal bilayer hydroxide catalyst comprises Ni as the first and second transition metal cations. 2+ and Fe 3+ , and in this case, the layered metal bilayer hydroxide catalyst can form an intermediate of NiOOH and FeOOH during the oxygen evolution reaction (OER).

[0021] A method for producing a layered metal bilayer hydroxide catalyst according to an embodiment of the present invention may include a first step of preparing a mixed solution by dissolving a first metal salt containing a first transition metal cation, a second metal salt containing a second transition metal cation, and an yttrium salt in an aqueous solvent; and a second step of adding the mixed solution and an alkaline aqueous solution to an aqueous solution containing an interlayer anion and stirring under an inert gas atmosphere, thereby preparing a layered metal bilayer hydroxide catalyst represented by the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0024] In the above chemical formula 1, M 1 is the first transition metal cation of +2, and M 2 is the second transition metal cation of +3, A is the interlayer anion of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

[0025] In one embodiment, the first metal salt may include Ni(NO3)2·6H2O, the second metal salt may include Fe(NO3)3·6H2O, and the yttrium salt may include Y(NO3)3·6H2O.

[0026] In one embodiment, the total molar number of the second metal salt and the yttrium salt is 20 to 50% of the molar number of the first metal salt, and the molar ratio of the second metal salt to the yttrium salt may be 20 or more and 150 or less.

[0027] In one embodiment, the first transition metal cation is Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn 2+ , Co 2+ , Fe 2+ and Cu 2+ comprising at least one selected from the group consisting of, wherein the second transition metal cation is Fe 3+ , Al 3+ , Cr 3+ , Mn 3+ , Ga 3+ , Co 3+ and Ni 3+ Contains at least one selected from the group consisting of, wherein the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- and H2PO4 -It may include one or more selected from the group consisting of .

[0028] In one embodiment, the second step comprises: preparing a reaction solution by adding the mixed solution and the alkaline aqueous solution to an aqueous solution containing the interlayer anion, and adjusting the pH of the reaction solution to 8.5 to 9.5; stirring the reaction solution in an inert gas atmosphere, thereby obtaining the M 1 , M 2 , Y 3+ And a step of forming a reactant by reacting an interlayer anion; and a step of freeze-drying the reactant to obtain a layered metal double layer hydroxide catalyst represented by the chemical formula 1.

[0029] In one embodiment, the inert gas atmosphere may be a nitrogen atmosphere.

[0030] In one embodiment, the alkaline aqueous solution may comprise about 1 to 3 M NaOH aqueous solution.

[0031] In one embodiment, the aqueous solution containing the interlayer anion may include an aqueous NaNO3 solution.

[0032] A water electrolysis device according to an embodiment of the present invention may include an ion exchange membrane and a first electrode and a second electrode facing each other with the ion exchange membrane interposed therebetween, and the first electrode where an oxygen evolution reaction (OER) occurs may include a layered metal double-layer hydroxide catalyst represented by the following chemical formula 1.

[0033] [Chemical Formula 1]

[0034] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0035] In the above chemical formula 1, M 1is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

[0036] In one embodiment, the first electrode includes a first catalyst layer disposed adjacent to the ion exchange membrane and a first gas diffusion layer disposed on the outside of the first catalyst layer, wherein the first catalyst layer may include the layered metal double layer hydroxide catalyst.

[0037] A metal-air secondary battery according to an embodiment of the present invention may include an air electrode and a metal electrode spaced apart from each other, and an electrolyte disposed between the air electrode and the metal electrode, and the air electrode may include a layered metal double-layer hydroxide catalyst represented by the following chemical formula 1.

[0038] [Chemical Formula 1]

[0039] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0040] In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

[0041] In one embodiment, the metal electrode may include any one metal selected from the group consisting of zinc (Zn), lithium (Li), and aluminum (Al).

[0042] According to the layered metal double layer hydroxide catalyst of the present invention, some of the first and second transition metal cations forming the lattice, for example, some of the +3-valent second transition metal cations, are Y 3+ By substituting with , the catalytic activity of OER reaction and ORR reaction can be significantly improved.

[0043] FIG. 1 is a flowchart illustrating a method for manufacturing a layered metal bilayer hydroxide catalyst according to an embodiment of the present invention.

[0044] Figure 2 is a drawing for explaining a water electrolysis device according to an embodiment of the present invention.

[0045] FIG. 3 is a drawing for explaining a metal-air secondary battery according to an embodiment of the present invention.

[0046] Figure 4 shows XRD pattern data measured for materials synthesized according to Examples 1 to 3 and Comparative Examples, respectively.

[0047] Figure 5 shows a TEM image (a), an elemental mapping image (b), and a STEM image (c) of a material synthesized according to Example 2.

[0048] Figure 6 shows XANES data of materials synthesized according to Example 2 and Comparative Example, respectively.

[0049] Figure 7 shows EXAFS data of materials synthesized according to Example 2 and Comparative Example, respectively.

[0050] Figure 8 shows data showing the electrochemical performance test results of catalysts synthesized according to Examples 1 to 3 and Comparative Examples, respectively.

[0051] Figure 9 shows the results of in situ Raman analysis during an oxygen generation reaction conducted to analyze the reaction mechanism of the catalysts synthesized according to Example 2 and Comparative Example.

[0052] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention may be modified in various ways and may take various forms. Therefore, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention. In describing each drawing, similar reference numerals are used to indicate similar components. In the attached drawings, the dimensions of structures are shown larger than actual size to ensure clarity of the present invention.

[0053] While terms like "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component."

[0054] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0055] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0056]

[0057] Layered metal bilayer hydroxide catalyst

[0058] A layered metal bilayer hydroxide catalyst according to an embodiment of the present invention is represented by the following chemical formula 1 and may have a layered metal bilayer structure substituted with yttrium (Y).

[0059] [Chemical Formula 1]

[0060] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0061] In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation having an oxidation state of +3, and A may be an interlayer anion having an oxidation state of -n. And a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수일 수 있다.

[0062] In one embodiment, the first transition metal cation is Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn2+ , Co 2+ , Fe 2+ , Cu 2+ It may include at least one selected from the group consisting of Fe, and the second transition metal cation is Fe 3+ , Al 3+ , Cr 3+ , Mn 3+ , Ga 3+ , Co 3+ , Ni 3+ It may include one or more selected from the group consisting of, and the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- , H2PO4 - It may include one or more selected from the group consisting of:

[0063] In one embodiment, the layered metal double layer hydroxide (LDH) catalyst comprises six hydroxide ions (OH - ) formed by coordination of the first octahedral structure, each of the second transition metal cations having six hydroxide ions (OH - ) and the second octahedral structure formed by coordination with the yttrium ion and seven hydroxide ions (OH - ) may have a structure in which the interlayer anions are arranged between the two-dimensional layered structures formed by covalently linking the decahedral structures formed by coordination. In one embodiment, each of the first and second transition metal cations may have an ionic radius smaller than that of the yttrium ion. According to the layered metal bilayer hydroxide catalyst of the present invention, the ability to adsorb oxygen evolution reaction reactants is strengthened due to the increased coordination number through yttrium (Y) substitution with a relatively large ionic radius, thereby more actively promoting the oxygen evolution reaction.

[0064] In one embodiment, the layered metal bilayer hydroxide catalyst may include Ni-Fe:Y LDH or Co-Fe:Y LDH.

[0065] In one embodiment, a+b may be about 0.2 or more and 0.5 or less, for example, about 0.3 to 0.4. And the molar ratio (a / b) of the second transition metal cation to the yttrium ion may be about 20 or more and 150 or less. When the molar ratio (a / b) of the second transition metal cation to the yttrium ion is less than 33, the change in the average coordination number in the lattice due to yttrium ion substitution may be minimal, thereby reducing the effect on the oxygen generation performance, and when it exceeds 100, a problem may occur in which yttrium (Y)-related impurities, such as Y(OH)3, appear together during the synthesis process. For example, the molar ratio (a / b) of the second transition metal cation to the yttrium ion may be about 33 or more and 105 or less, or about 40 or more and 75 or less.

[0066] In one embodiment, the layered metal bilayer hydroxide catalyst may have a nanosheet form. For example, the layered metal bilayer hydroxide catalyst may have a nanosheet form having a size of about 20 to 1000 nm.

[0067] According to the layered metal bilayer hydroxide catalyst of the present invention, some of the first and second transition metal cations forming the lattice, for example, some of the +3-valent second transition metal cations, are Y 3+ By substituting with , the catalytic activity of OER reaction and ORR reaction can be significantly improved.

[0068]

[0069] <Method for producing a layered metal double-layer hydroxide catalyst>

[0070] FIG. 1 is a flowchart illustrating a method for manufacturing a layered metal bilayer hydroxide catalyst according to an embodiment of the present invention.

[0071] Referring to FIG. 1, a method for producing a layered metal bilayer hydroxide catalyst according to an embodiment of the present invention may include a first step (S110) of preparing a mixed solution by dissolving a first metal salt containing M1, a second metal salt containing M2, and an yttrium salt in an aqueous solvent; and a second step (S120) of adding the mixed solution and an alkaline aqueous solution to an aqueous solution containing an interlayer anion and stirring under an inert gas atmosphere to produce a layered metal bilayer hydroxide catalyst represented by the following chemical formula 1.

[0072] [Chemical Formula 1]

[0073] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O

[0074] In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation having an oxidation state of +3, and A may be an interlayer anion having an oxidation state of -n. And a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수일 수 있다.

[0075] In the first step (S110), the first metal salt may include a first nitride containing the first transition metal cation described above, the second metal salt may include a second nitride containing the second transition metal cation described above, and the yttrium salt may include a third nitride containing a +3-valent yttrium ion. For example, when the layered metal bilayer hydroxide catalyst includes Ni-Fe LDH, the first metal salt may include Ni(NO3)2·6H2O, the second metal salt may include Fe(NO3)3·6H2O, and the yttrium salt may include Y(NO3)3·6H2O.

[0076] In one embodiment, the total mole number (a+b) of the second metal salt and the yttrium salt may be about 20 to 50% of the mole number of the first metal salt. And the mole ratio (a / b) of the second metal salt to the yttrium salt may be about 20 to 150.

[0077] In one embodiment, water may be used as the aqueous solvent of the mixed solution. For example, decarbonated distilled water may be used as the aqueous solvent. Here, decarbonated distilled water refers to distilled water obtained by boiling tertiary distilled water in a nitrogen atmosphere and then cooling it, and carbonate ions (CO3) present in general distilled water - ) is removed, so when using it, the interlayer anion NO3 is removed during the process of synthesizing LDH. - can be adjusted.

[0078] In the above second step (S120), the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- , H2PO4 -It may include one or more selected from the group consisting of etc. In one embodiment, the aqueous solution containing the interlayer anion may include an aqueous solution of NaNO3. And the aqueous alkaline solution may include an aqueous solution of about 1 to 3 M of NaOH. Meanwhile, the inert gas atmosphere may be a nitrogen atmosphere.

[0079] In one embodiment, the second step (S120) comprises: a step of preparing a reaction solution by adding the mixed solution and the alkaline aqueous solution one drop at a time to the aqueous solution containing the interlayer anion, and adjusting the pH of the reaction solution to 8.5 to 9.5; stirring the reaction solution in an inert gas atmosphere, thereby preparing the M 1 , M 2 , Y 3+ And a step of forming a reactant by reacting an interlayer anion; and a step of freeze-drying the reactant to obtain a layered metal double layer hydroxide catalyst represented by the chemical formula 1; In this case, the reaction solution is stirred in an inert gas atmosphere, and the M 1 , M 2, Y 3+ And by reacting the interlayer anion, the above reactant is formed, so carbonate ion (CO3 2- ) can be removed.

[0080] Through the manufacturing method of the present invention, a layered metal double-layer hydroxide catalyst in the form of nanosheets having a size of about 20 to 600 nm can be manufactured.

[0081]

[0082] <Water electrolysis device>

[0083] Figure 2 is a drawing for explaining a water electrolysis device according to an embodiment of the present invention.

[0084] Referring to FIG. 2, a water electrolysis device (100) according to an embodiment of the present invention may include an ion exchange membrane (110), a first electrode (120), and a second electrode (130).

[0085] The ion exchange membrane (110) may be any ion exchange membrane applicable to a known water electrolysis device without limitation. For example, the ion exchange membrane (110) may include a cation exchange membrane or an anion exchange membrane.

[0086] The first electrode (120) and the second electrode (130) may be arranged to face each other with the ion exchange membrane (110) interposed therebetween.

[0087] An oxygen evolution reaction (OER) can occur at the first electrode (120), and a hydrogen evolution reaction (HER) can occur at the second electrode (130).

[0088] The first electrode (120) may include a first catalyst layer (121) disposed adjacent to the ion exchange membrane (110) and a first gas diffusion layer (122) disposed on the outside of the first catalyst layer (121).

[0089] In one embodiment, the first catalyst layer (121) may include a layered metal double layer hydroxide catalyst according to the embodiment of the present invention described above, and the first gas diffusion layer (122) may be a gas diffusion layer applied to a known water electrolysis device, without limitation.

[0090] The second electrode layer (130) may include a second catalyst layer (131) disposed to face the first catalyst layer (121) with the ion exchange membrane (110) interposed therebetween, and a second gas diffusion layer (132) disposed on the outer side of the second catalyst layer (131). As the second catalyst layer (131) and the second gas diffusion layer (132), a catalyst layer and a gas diffusion layer applied to a hydrogen generation electrode of a known water electrolysis device may be applied without limitation.

[0091]

[0092] Metal-air secondary battery

[0093] FIG. 3 is a drawing for explaining a metal-air secondary battery according to an embodiment of the present invention.

[0094] Referring to FIG. 3, a metal-air secondary battery (200) according to an embodiment of the present invention may include an air electrode (220), a metal electrode (230), and an electrolyte (210).

[0095] The air electrode (220) and the metal electrode (230) may be spaced apart from each other with the electrolyte (210) interposed therebetween.

[0096] The above-described air electrode (220) may have a porous structure and may include a catalyst for oxygen reduction reaction (ORR). For example, the above-described air electrode (220) may include a layered metal double-layer hydroxide catalyst according to the embodiment of the present invention described above.

[0097] The above metal electrode (230) may include a metal such as zinc (Zn), lithium (Li), or aluminum (Al).

[0098] When the metal-air secondary battery (200) is discharged, hydroxide ions (OH-) may be generated at the air electrode (220) through an oxygen reduction reaction (ORR), and metal hydroxide and electrons may be generated at the metal electrode (230) through a reaction between the metal forming the metal electrode (230) and the hydroxide ions. In addition, when the metal-air secondary battery (200) is charged, oxygen, water, and electrons may be generated from the hydroxide ions (OH-) at the air electrode (220), and metal, water, and hydroxide ions may be generated at the metal electrode (230) through a reaction between the metal hydroxide and electrons.

[0099]

[0100] Hereinafter, specific embodiments of the present invention will be described in detail. However, the following examples are merely some embodiments of the present invention, and the scope of the present invention is not limited to the following examples.

[0101]

[0102] [Examples 1 to 3]: Synthesis of NiFeY-LDH.

[0103] A mixed solution was prepared by dissolving 6.6 mmol of Ni(NO3)2·6H2O, (3.3-x) mmol of Fe(NO3)3·6H2O, and x mmol of Y(NO3)3·6H2O (Company: Sigma-Aldrich) in 40 ml of decarbonated distilled water, and a 1 M NaOH solution was prepared using the decarbonated distilled water, and 13.2 mmol of NaNO3 (Company: Thermo Fisher Scientific) was dissolved in 100 ml of decarbonated distilled water and stirred to prepare a NaNO3 solution.

[0104] Next, the above mixed solution and the above NaOH solution were added dropwise to the above NaNO3 solution and mixed, and then the pH was adjusted to 9. The mixture was stirred for 24 hours while flowing nitrogen gas to form NiFeY-LDH.

[0105] Next, the crystal-grown NiFeY-LDH was sufficiently washed with decarbonized distilled water and then freeze-dried for 12 hours to obtain the final NiFeY-LDH.

[0106] Here, the molar number of Y(NO3)3·6H2O was synthesized at three molar numbers, x= 0.033 (Example 1), 0.066 (Example 2), and 0.099 (Example 3), respectively, and the synthesized samples were named NiFe-LDH, NiFeY-LDH-1, NiFeY-LDH-2, and NiFeY-LDH-3.

[0107]

[0108] [Comparative example]

[0109] NiFe-LDH was synthesized in the same manner as in Examples 1 to 3, except that Y(NO3)3·6H2O was not added as a control.

[0110]

[0111] [Experimental Example]

[0112] 7 mg of the materials synthesized according to Examples 1 to 3 and Comparative Examples and 3 mg of conductive carbon (Vulcan-XC72R) were added to 4 ml of tertiary distilled water and 1 ml of isopropanol solution, and then 40 ml of a 5 wt% Nafion solution was added thereto and dispersed for 1 hour using ultrasonic waves. 10 ml of the dispersed solution was applied to a Glassy Carbon (GC) electrode to manufacture a working electrode.

[0113] The oxygen evolution reaction (OER) performance was tested using a three-electrode system equipped with a working electrode manufactured by RRDE-3A Rotating Ring Disk Electrode Apparatus (ALS). The SCE standard was used as the reference electrode, a Pt wire as the counter electrode, and a 1 M KOH solution as the electrolyte.

[0114]

[0115] Figure 4 shows XRD pattern data measured for materials synthesized according to Examples 1 to 3 and Comparative Examples, respectively.

[0116] Referring to Fig. 4, it can be confirmed that NiFe-LDH and Y-substituted NiFeY-LDH-1, NiFeY-LDH-2, and NiFeY-LDH-3 all have a typical NiFe-LDH crystal structure. In other words, it was confirmed that an impurity-free LDH structure can be realized even if Y is substituted.

[0117] Figure 5 shows a TEM image (a), an elemental mapping image (b), and a STEM image (c) of a material synthesized according to Example 2.

[0118] Referring to Fig. 5, NiFeY-LDH-2 was confirmed to have a nanosheet shape with a size of about 800 nm (see a), Y was confirmed to be uniformly distributed throughout NiFeY-LDH-2 (see b), and Y was confirmed to be substituted within the crystal lattice (see c).

[0119] Figure 6 shows XANES data of materials synthesized according to Example 2 and Comparative Example, respectively.

[0120] Referring to Fig. 6, it was confirmed through Ni K-edge, Fe K-edge, and Y K-edge XANES analysis that the crystal structure of LDH was maintained even after Y substitution, and through comparison with NiO, FeO, Fe2O3, and Y(OH)3 reference materials, nickel, iron, and yttrium in the NiFeY-LDH-2 material were Ni 2+ , Fe 3+ , Y 3+ It was confirmed that it has an oxidation state of .

[0121] Figure 7 shows EXAFS data of materials synthesized according to Example 2 and Comparative Example, respectively.

[0122] Referring to Fig. 7, Ni K-edge and Fe K-edge EXAFS analyses confirmed that the crystal structure was maintained even after Y substitution. In addition, Y K-edge EXAFS analysis confirmed that the metal-metal FT EXAFS peaks in NiFeY-LDH-2 appeared at different positions compared to the Y(OH)3 data, confirming that Y(OH)3 phase was not additionally generated in NiFeY-LDH-2, but rather that Y was substituted into the NiFe-LDH lattice.

[0123] Figure 8 shows data showing the electrochemical performance test results of catalysts synthesized according to Examples 1 to 3 and Comparative Examples, respectively. All materials were measured in a 1 M KOH solution at a scan rate of 5 mV / s.

[0124] As shown in Fig. 8a, the catalysts synthesized according to Examples 1 to 3 were found to have lower overvoltage and higher current than the catalysts synthesized according to Comparative Examples, and it can be confirmed from this that the substitution of Y helps improve the electrochemical catalytic performance of LDH.

[0125] As shown in Figures 8b, c, and d, the catalysts synthesized according to Examples 1 to 3 were found to have smaller Tafel slopes, larger ECSA values, and smaller charge transfer resistances compared to the catalysts synthesized according to Comparative Examples. Among the catalysts synthesized according to Examples 1 to 3, NiFeY-LDH-2 exhibited the best catalytic performance, which is much better than that of conventional commercialized Ir / C and RuO2 catalyst materials.

[0126] Figure 9 shows the results of in situ Raman analysis during an oxygen generation reaction conducted to analyze the reaction mechanism of the catalysts synthesized according to Example 2 and Comparative Example.

[0127] Referring to Fig. 9, both NiFe-LDH and NiFeY-LDH-2 samples were found to maintain the original LDH structure at 1.5 V. However, in the case of the NiFeY-LDH-2 sample, a peak corresponding to NiOOH, an oxygen evolution reaction intermediate, appeared at 1.55 V, whereas in the case of NiFe-LDH, a NiOOH peak appeared at 1.6 V. These results indicate that the NiFeY-LDH-2 sample exhibits superior catalytic performance because the oxygen evolution reaction occurs at a lower voltage.

[0128] In addition, at 1.65 V, a peak corresponding to FeOOH, which does not appear in NiFe-LDH, appeared in NiFeY-LDH-2, indicating that Fe additionally contributes to the oxygen evolution reaction in the NiFeY-LDH-2 sample. That is, when Y element is substituted into NiFe-LDH according to the present invention, it can exhibit better catalytic performance for the oxygen evolution reaction due to the relatively rapid formation of NiOOH intermediate during the oxygen evolution reaction and the additional formation of FeOOH intermediate that does not appear in the existing NiFe-LDH.

[0129]

[0130] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A layered metal bilayer hydroxide catalyst represented by the following chemical formula 1, having a layered bilayer structure, and having catalytic activity for oxygen evolution reaction (OER) or oxygen reduction reaction (ORR): [Chemical Formula 1] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

2. In paragraph 1, The first transition metal cation is Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn 2+ , Co 2+ , Fe 2+ and Cu 2+ comprising at least one selected from the group consisting of, wherein the second transition metal cation is Fe 3+ , Al 3+ , Cr 3+ , Mn 3+ , Ga 3+ , Co 3+ and Ni 3+ Contains at least one selected from the group consisting of, wherein the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- and H2PO4 - A layered metal bilayer hydroxide catalyst, characterized in that it comprises at least one selected from the group consisting of:

3. In paragraph 1, A layered metal double layer hydroxide catalyst, characterized in that the yttrium (Y) cation exists in the lattice in a form in which a portion of the second transition metal cation is substituted.

4. In paragraph 3, The above layered metal double layer hydroxide catalyst is such that each of the first transition metal cations has six hydroxide ions (OH - ) formed by coordination of the first octahedral structure, each of the second transition metal cations having six hydroxide ions (OH - ) and the second octahedral structure formed by coordination with the yttrium ion and seven hydroxide ions (OH - A layered metal bilayer hydroxide catalyst characterized by comprising a decahedral structure formed by coordination by ) .

5. In paragraph 2, a+b is approximately 0.2 or more and 0.5 or less, A layered metal bilayer hydroxide catalyst, characterized in that the molar ratio (a / b) of the second transition metal cation to the yttrium ion is 20 or more and 150 or less.

6. In paragraph 5, A layered metal bilayer hydroxide catalyst, characterized in that the molar ratio (a / b) of the second transition metal cation to the yttrium ion is 33 or more and 105 or less.

7. In paragraph 1, A layered metal double layer hydroxide catalyst, characterized in that the layered metal double layer hydroxide catalyst has a nanosheet form having a size of 20 to 1000 nm.

8. In paragraph 1, The above layered metal double layer hydroxide catalyst comprises Ni as the first and second transition metal cations. 2+ and Fe 3+ Including, A layered metal bilayer hydroxide catalyst characterized by forming intermediates of NiOOH and FeOOH during an oxygen evolution reaction (OER).

9. A first step of preparing a mixed solution by dissolving a first metal salt containing a first transition metal cation, a second metal salt containing a second transition metal cation, and an yttrium salt in an aqueous solvent; and A method for producing a layered metal bilayer hydroxide catalyst, comprising: a second step of producing a layered metal bilayer hydroxide catalyst represented by the following chemical formula 1 by adding the above mixed solution and an alkaline aqueous solution to an aqueous solution containing an interlayer anion and stirring the mixture under an inert gas atmosphere; [Chemical Formula 1] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O In the above chemical formula 1, M 1 is the first transition metal cation of +2, and M 2 is the second transition metal cation of +3, A is the interlayer anion of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

10. In paragraph 9, A method for producing a layered metal double-layer hydroxide catalyst, characterized in that the first metal salt comprises Ni(NO3)2·6H2O, the second metal salt comprises Fe(NO3)3·6H2O, and the yttrium salt comprises Y(NO3)3·6H2O.

11. In paragraph 9, A method for producing a layered metal bilayer hydroxide catalyst, characterized in that the total molar number of the second metal salt and the yttrium salt is 20 to 50% of the molar number of the first metal salt, and the molar ratio of the second metal salt to the yttrium salt is 20 or more and 150 or less.

12. In paragraph 11, The first transition metal cation is Ca 2+ , Mg 2+ , Zn 2+ , Ni 2+ , Mn 2+ , Co 2+ , Fe 2+ and Cu 2+ comprising at least one selected from the group consisting of, wherein the second transition metal cation is Fe 3+ , Al 3+ , Cr 3+ , Mn 3+ , Ga 3+ , Co 3+ and Ni 3+ Contains at least one selected from the group consisting of, wherein the interlayer anion is OH - , NO3 - , PO4 3- , HPO4 2- and H2PO4 - A method for producing a layered metal bilayer hydroxide catalyst, characterized in that it comprises at least one selected from the group consisting of:

13. In paragraph 12, The second step above is, A step of preparing a reaction solution by adding the mixed solution and the alkaline aqueous solution to an aqueous solution containing the interlayer anion, and adjusting the pH of the reaction solution to 8.5 to 9.5; By stirring the above reaction solution in an inert gas atmosphere, the above M 1 , M 2 , Y 3+ and forming a reactant by reacting an interlayer anion; and A method for producing a layered metal double-layer hydroxide catalyst, characterized by comprising a step of freeze-drying the above reactant to obtain a layered metal double-layer hydroxide catalyst represented by the above chemical formula 1.

14. In paragraph 13, A method for producing a layered metal double layer hydroxide catalyst, characterized in that the above inert gas atmosphere is a nitrogen atmosphere.

15. In paragraph 13, A method for producing a layered metal double layer hydroxide catalyst, characterized in that the above alkaline aqueous solution contains an aqueous NaOH solution of about 1 to 3 M.

16. In paragraph 15, A method for producing a layered metal double layer hydroxide catalyst, characterized in that the aqueous solution containing the interlayer anion comprises an aqueous NaNO3 solution.

17. In a water electrolysis device including an ion exchange membrane and a first electrode and a second electrode facing each other with the ion exchange membrane interposed therebetween, A water electrolysis device characterized in that the first electrode where the oxygen evolution reaction (OER) occurs comprises a layered metal double layer hydroxide catalyst represented by the following chemical formula 1: [Chemical Formula 1] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

18. In paragraph 17, The first electrode includes a first catalyst layer disposed adjacent to the ion exchange membrane and a first gas diffusion layer disposed on the outside of the first catalyst layer, A water electrolysis device, characterized in that the first catalyst layer comprises the layered metal double layer hydroxide catalyst.

19. In a metal-air secondary battery including an air electrode and a metal electrode spaced apart from each other and an electrolyte disposed between the air electrode and the metal electrode, A metal-air secondary battery, characterized in that the air electrode comprises a layered metal double layer hydroxide catalyst represented by the following chemical formula 1: [Chemical Formula 1] [M 1 1-(a+b) M 2 a Y 3+ b (OH)2][A n- ] (a+b) / n ·cH2O In the above chemical formula 1, M 1 is a first transition metal cation with an oxidation state of +2, and M 2 is a second transition metal cation with an oxidation state of +3, A is an interlayer anion with an oxidation state of -n, and a and b are each "0 <a+b<1"의 조건을 만족하는 양의 실수이고, n은 1 이상 5 이하의 정수이며, c는 양의 실수이다.

20. In paragraph 19, A metal-air secondary battery, characterized in that the metal electrode comprises any one metal selected from the group consisting of zinc (Zn), lithium (Li), and aluminum (Al).

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