Catalyst for oxygen evolution reaction of water electrolysis cell, method for manufacturing same, and membrane-electrode assembly for water electrolysis cell and water electrolysis cell comprising same

Abstract

The present disclosure relates to: a catalyst for an oxygen evolution reaction of a water electrolysis cell; a method for manufacturing same; and a membrane-electrode assembly for a water electrolysis cell, and a water electrolysis cell, comprising same. More specifically, by manufacturing a catalyst for oxygen evolution reaction of a water electrolysis cell, having a structure in which active particles fill pores between nanoparticles of a carrier assembly manufactured in various forms or penetrate into the carrier assembly while being supported by the carrier assembly, performance is improved while reducing the amount of noble metal used. The active particles have stronger bonds than a form in which active particles are simply supported, and thus the active particles and the carrier assembly can have improved durability.

Description

Catalyst for oxygen generation reaction in electrolytic cell and method for producing same, and membrane-electrode assembly and electrolytic cell for electrolytic cell including same

[0001] The present disclosure relates to a catalyst for an oxygen evolution reaction in a water electrolysis cell and a method for producing the same, and a membrane-electrode assembly for an electrolysis cell and a water electrolysis cell including the same, and more particularly, to a catalyst for an oxygen evolution reaction in a water electrolysis cell having a structure in which active particles fill pores between nanoparticles of a carrier assembly manufactured in various forms or are supported on the carrier assembly and penetrate into the interior thereof, thereby reducing the amount of precious metal used while improving performance, and in which the durability of the active particles and the carrier assembly is improved by having a stronger bond than in a form in which the active particles are simply supported, and a method for producing the same, and a membrane-electrode assembly for an electrolysis cell and a water electrolysis cell including the same.

[0002] This disclosure relates to the results of a project (Project ID: 20022451) carried out with the support of the Materials and Components Technology Development Project of the Ministry of Trade, Industry and Energy and the Korea Institute for Advancement of Technology (KEIT).

[0003] Recent energy demands and environmental concerns demand sustainable supply, environmental friendliness, and high efficiency, leading to a growing need for the development of new energy sources and energy-utilizing devices. Renewable energy sources, such as solar and wind power, are attracting significant attention due to their environmentally friendly and sustainable characteristics and advantages, as well as their potential to replace fossil fuels, which are causing environmental problems and are depleting.

[0004] However, the supply of these renewable energies is unstable due to unstable weather conditions, regional constraints, and characteristics, which hinders their expansion as next-generation power sources.

[0005] To overcome this, hydrogen is attracting attention as a raw material for renewable energy.

[0006] Hydrogen energy is classified into gray, blue, and green hydrogen depending on the production method. Gray hydrogen refers to byproduct hydrogen produced as a byproduct of petrochemical or steelmaking processes and extracted hydrogen produced through a catalytic reaction using fossil fuels. Blue hydrogen refers to hydrogen that captures the carbon dioxide emitted when producing gray hydrogen and does not emit it into the atmosphere.

[0007] Gray and blue hydrogen have the problem that carbon dioxide is produced during the production process or cannot be completely removed because it uses fossil fuels.

[0008] Green hydrogen refers to hydrogen produced through the electrolysis of infinite water. Because the hydrogen production process produces no carbon dioxide, it is attracting attention as the ultimate eco-friendly energy source. Water electrolysis technology is necessary to produce green hydrogen.

[0009] Water electrolysis is an electrochemical technology that generates hydrogen and oxygen by electrolyzing water and transporting ions across a membrane. Water electrolysis can be divided into two half-cell reactions: the hydrogen evolution reaction (HER), which occurs at the reduction electrode, and the oxygen evolution reaction (OER), which occurs at the oxidation electrode.

[0010] The types of electrolysis mentioned above are, depending on the electrolyte membrane, representative ones such as polymer electrolyte membrane electrolysis (PEM), alkaline electrolysis (AEC), anion exchange membrane electrolysis (AEM), and solid oxide electrolysis (SOECs).

[0011] This technology relates to a catalyst for electrolysis, particularly a catalyst for an oxygen evolution electrode of a polymer electrolyte membrane (PEM) electrolysis. Conventionally, iridium black and iridium oxide powder have been used as catalysts for oxygen evolution reactions in polymer electrolyte membrane electrolysis oxygen evolution electrodes, but improvements are required for their low dispersibility, low electrical conductivity, and instability.

[0012] Additionally, there is a need to reduce the use of iridium due to the high price of iridium raw materials.

[0013] According to one embodiment, by manufacturing a catalyst for an oxygen evolution reaction of a water electrolysis cell having a structure in which active particles fill pores between nanoparticles of a carrier assembly manufactured in various forms or penetrate the interior thereof while being supported on the carrier assembly, the amount of precious metal used is reduced while performance is improved, and the durability of the active particles and the carrier assembly is improved by having a stronger bond than in a form in which the active particles are simply supported.

[0014] According to another embodiment, a method for producing a catalyst for oxygen generation reaction of the above-described electrolysis cell is provided.

[0015] According to another embodiment, a membrane-electrode assembly and a water electrolysis cell including a catalyst for an oxygen generation reaction of the water electrolysis cell are provided.

[0016] A catalyst for an oxygen generation reaction of a water electrolysis cell according to one embodiment comprises: a carrier assembly in which a plurality of nanoparticles are aggregated; and active particles filling pores between the nanoparticles of the carrier assembly or supported on the carrier assembly; wherein the nanoparticles include a first metal oxide, and the active particles may include a second metal oxide different from the first metal oxide.

[0017] The BET surface area of ​​the above carrier aggregate is 100 m 2 / g to 300 m 2 / g can be within the range.

[0018] The above carrier aggregate may have a nanosphere or nanowire shape.

[0019] When the above carrier aggregate has the nanosphere shape, the oxygen generation reaction catalyst of the water electrolysis cell also has the nanosphere shape, and the diameter of the catalyst may be in the range of 40 nm to 400 nm.

[0020] When the above carrier assembly has the nanowire shape, the oxygen generation reaction catalyst of the electrolysis cell also has the nanowire shape, and the diameter of the catalyst (w r ) and length (w l ) ratio (w) r / w l ) can be in the range of 0.05 to 0.9.

[0021] The diameter of the above nanoparticles may be in the range of 2 nm to 40 nm.

[0022] The first metal oxide may include titanium dioxide (TiO2).

[0023] The second metal oxide may include a noble metal oxide.

[0024] The above precious metal oxide is IrO x (wherein x is an integer from 1 to 3), RuO x (where x is an integer from 1 to 3), IrMO x (wherein M includes Ru, Pt, Sn, Se, Sb, Ta, Te, Nb, W, Zn, Au, or a combination thereof, and x is an integer from 1 to 3), or a combination thereof.

[0025] The above active particles may be included in an amount of 20 wt% to 70 wt% based on 100 wt% of the oxygen generation reaction catalyst.

[0026] A method for manufacturing a catalyst for an oxygen generation reaction of a water electrolysis cell according to another embodiment includes forming a carrier aggregate by agglomerating nanoparticles containing a first metal oxide, and filling pores between the nanoparticles of the carrier aggregate with active particles containing a second metal oxide.

[0027] The method for producing a catalyst for oxygen generation reaction of the above electrolysis cell further includes producing nanoparticles including a first metal oxide using a first metal oxide precursor, and the first metal oxide precursor may include titanium alkoxide, TiCl4, Ti(OH)4, Ti(SO4)2, or a combination thereof.

[0028] Forming a carrier aggregate by agglomerating nanoparticles containing the first metal oxide may be accomplished by dispersing nanoparticles containing the first metal oxide in a solvent and then agglomerating them to form a carrier aggregate having a nanosphere shape; or by filling a mold with nanoparticles containing the first metal oxide to form a carrier aggregate having a nanowire shape.

[0029] Filling the pores between the nanoparticles of the carrier assembly with the active particles including the second metal oxide includes mixing an active particle precursor and a weak reducing agent in a solution including the carrier assembly so that the weight ratio is in the range of 1:1 to 1:10 to obtain a precursor solution, performing a vacuum adsorption process on the precursor solution to adsorb the active particle precursor into the pores between the nanoparticles of the carrier assembly, and performing a heat treatment process on the precursor solution after performing the vacuum adsorption process, wherein the active particle precursor includes a noble metal chloride, a noble metal acetate, a noble metal amine, or a combination thereof, and the weak reducing agent may include formaldehyde, formic acid, oxalic acid, ascorbic acid, citric acid, urea, ethylenediamine, hexamethylenetetramine, or a mixture thereof.

[0030] The above vacuum adsorption can be performed at 5 kPa to 20 kPa.

[0031] The above heat treatment process can be performed at a temperature of 80°C to 140°C for 1 to 4 hours.

[0032] According to another embodiment, a membrane-electrode assembly for a water electrolysis cell may include: a polymer electrolyte membrane; an oxygen generation electrode positioned on one side of the polymer electrolyte membrane and including a catalyst for an oxygen generation reaction of the water electrolysis cell and an ion conductor; and a hydrogen generation electrode positioned on the other side of the polymer electrolyte membrane and including a carbon-based carrier and active particles supported on the carbon-based carrier and including a noble metal.

[0033] The membrane-electrode assembly for the above-mentioned electrolytic cell may have a voltage increase rate of 3% or less, as expressed by the following equation 1.

[0034] [Formula 1]

[0035] Voltage increase rate (%) = (voltage after driving - initial voltage) / (initial voltage) × 100

[0036] The above oxygen generation electrode may contain the oxygen generation reaction catalyst in a range of 65 wt% to 95 wt% based on 100 wt% of the oxygen generation electrode.

[0037] The polymer electrolyte membrane may include a porous support including a plurality of pores, and an ion conductor filling the pores of the porous support.

[0038] According to another embodiment, a hydroelectric cell comprises the membrane-electrode assembly.

[0039] According to one embodiment, a catalyst for an oxygen evolution reaction of a water electrolysis cell has a structure in which active particles fill pores between nanoparticles of a carrier assembly manufactured in various forms or penetrate into the interior of the carrier assembly while being supported thereon, thereby reducing the amount of precious metal used while improving performance, and the durability of the active particles and the carrier assembly can be improved by having a stronger bond than when the active particles are simply supported.

[0040] FIG. 1 is a schematic diagram showing a catalyst for an oxygen evolution reaction in a water electrolysis cell including a carrier assembly and active particles having a nanosphere shape according to one embodiment.

[0041] FIG. 2 is a schematic diagram showing a catalyst for oxygen generation reaction in a water electrolysis cell including a carrier assembly and active particles having a nanowire shape according to one embodiment.

[0042] FIG. 3 is a schematic diagram showing a membrane-electrode assembly (MEA) for a water electrolysis cell according to another embodiment.

[0043] Figures 4 and 5 are scanning electron microscope (SEM) photographs of a catalyst for oxygen evolution reaction in a water electrolysis cell including a carrier aggregate and active particles manufactured in Manufacturing Examples 2-1 and 2-2, respectively.

[0044] Figure 6 is a transmission electron microscope (TEM) photograph of a catalyst for oxygen generation reaction supported on TiO2 of Comparative Example 3.

[0045] Figure 7 is a graph showing the results of BET specific surface area analysis of the carrier assembly manufactured in Manufacturing Examples 2-1 and 2-2 and the oxygen generation reaction catalyst of the electrolysis cell manufactured in Examples 1 and 2 including the carrier assembly.

[0046] Figure 8 is a graph showing the results of evaluating the IV characteristics of a membrane-electrode assembly including an oxygen evolution reaction catalyst of a water electrolysis cell manufactured in Examples 1 and 2 and Comparative Examples 1 to 3.

[0047] Hereinafter, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

[0048] As used herein, “combination thereof” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0049] It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0050] In this specification, terms are used solely to distinguish one component from another. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0051] Unless otherwise defined herein, "substitution" means that a hydrogen atom in a compound is replaced by a halogen atom (F, Cl, Br or I), a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C7 to C30 arylalkyl group, a C1 to C4 alkoxy group, a C1 to C20 heteroalkyl group, a C3 to C20 heteroarylalkyl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C15 cycloalkynyl group, It means substituted with a substituent including a C2 to C20 heterocycloalkyl group or a combination thereof.

[0052] Unless otherwise defined herein, “alkyl group” means a straight or branched chain, saturated, monovalent hydrocarbon group (e.g., methyl group, ethyl group, propyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, iso-amyl group, hexyl group, etc.).

[0053] Unless otherwise defined herein, “alkenyl group” means a straight or branched chain, saturated, monovalent hydrocarbon group having at least one carbon-carbon double bond (e.g., an ethenyl group).

[0054] Unless otherwise defined herein, “alkoxy group” means an alkyl group linked through oxygen, for example, methoxy, ethoxy, and sec-butyloxy groups.

[0055]

[0056] 1. Catalyst for oxygen generation reaction in electrolysis cell

[0057] In this specification, the catalyst for oxygen evolution reaction means a catalyst applied to an electrode (hereinafter, “oxygen evolution electrode”) where an oxygen evolution reaction (OER) takes place. That is, it is a catalyst included in the oxygen evolution electrode described below.

[0058] A catalyst for an oxygen generation reaction in a water electrolysis cell according to one embodiment includes a carrier aggregate in which a plurality of nanoparticles are aggregated and active particles that fill pores between the nanoparticles of the carrier aggregate or are supported on the carrier aggregate.

[0059] The carrier aggregates and active particles are described in detail below.

[0060] The above carrier aggregate refers to a carrier having a structure in which a plurality of nanoparticles are aggregated. At this time, the plurality of nanoparticles are aggregated to a degree that pores can exist between the nanoparticles, and thus the carrier aggregate can have pores between the nanoparticles.

[0061] The carrier aggregate due to the above pores may have a BET specific surface area within a predetermined range. The method for measuring the BET specific surface area is according to the method described in "BET specific surface area analysis" in Evaluation Example 1 of this specification.

[0062] For example, the lower limit of the BET surface area of ​​the above carrier aggregate is 100 m 2 / g, 110 m 2 / g, 120 m 2 / g, 130 m 2 / g, 140 m 2 / g, 150 m 2 / g, 160 m 2 / g,170 m 2 / g, 180 m 2 / g, 190 m 2 / g, 200 m 2 / g, 205 m 2 / g, 210 m 2 / g, 215 m 2 / g, 220 m 2 / g, 225 m 2 / g, 230 m 2 / g 235 m 2 / g can be about, and its upper limit is 300 m 2 / g, 295 m 2 / g, 290 m 2 / g, 285 m 2 / g, 280 m 2 / g, 275 m 2 / g, 270 m 2 / g, 265 m 2 / g, 260 m 2 / g, 255 m 2 / g, 250 m 2 / g, 245 m 2 / g, 240 m 2 / g, 234 m 2 / g, 230 m 2 / g, 225 m 2 / g, 220 m 2 / g, 215 m 2 / g, 210 m 2 / g or 205 m 2 It could be around / g.

[0063] The BET specific surface area of ​​the carrier aggregate may be greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0064] When the BET specific surface area of ​​the carrier assembly satisfies the above range, the active particles have a strong bonding force with the carrier assembly, so that the durability of the active particles and the carrier assembly can be improved, and the active particles can be sufficiently filled in the pores of the carrier assembly, so that the catalyst can have sufficient activity. In addition, it may be realistically difficult to manufacture a carrier assembly having a BET specific surface area exceeding the above by agglomerating a plurality of nanoparticles. This is because the nanoparticles forming the carrier assembly do not have a porous form with separate pores.

[0065] The above carrier aggregate may have various shapes as a result of the aggregation of the plurality of nanoparticles. For example, the carrier aggregate may have a shape such as a nanosphere, nanowire, nanorod, nanosheet, or nanocapsule.

[0066] According to one embodiment, the carrier assembly may have a nanosphere or nanowire shape. The shape of the oxygen generation reaction catalyst of the electrolysis cell may be determined according to the shape of the carrier assembly.

[0067] According to one embodiment, the carrier assembly may have a nanosphere shape. When the carrier assembly has a nanosphere shape, the BET specific surface area of ​​the carrier assembly is 100 m 2 / g to 250 m 2 / g can be within the range.

[0068] When the above carrier assembly has the nanosphere shape, the oxygen generation reaction catalyst of the electrolysis cell including the carrier assembly may also have the nanosphere shape.

[0069] Figure 1 shows a catalyst (A) for oxygen generation reaction of a water electrolysis cell including a carrier assembly (A) having the above nanosphere shape. ' ) is a schematic diagram showing a carrier assembly (A) having a nanosphere shape in which a plurality of nanoparticles (1) are aggregated, and a catalyst (A) for oxygen generation reaction of a water electrolysis cell including a carrier assembly having a nanosphere shape in which a plurality of nanoparticles (1) are aggregated and active particles (2) filling the pores of the carrier assembly or supported on the carrier assembly ' ) is shown.

[0070] As shown in Fig. 1, an oxygen generation catalyst (A) comprising a carrier assembly having a nanosphere shape ' ) may have a nanosphere shape, which is the same shape as the carrier aggregate (A).

[0071] The diameter of the oxygen evolution reaction catalyst having the above nanosphere shape may be within a predetermined range. The diameter of the oxygen evolution reaction catalyst can be measured from a photograph of the oxygen evolution reaction catalyst taken using a scanning electron microscope (SEM). The diameter may be an average diameter. In this case, the average diameter of the oxygen evolution reaction catalyst can be calculated by dividing the sum of the diameters of the oxygen evolution reaction catalysts measured from photographs of the oxygen evolution reaction catalysts taken using a scanning electron microscope (SEM) by the number of the measured oxygen evolution reaction catalysts.

[0072] The lower limit of the diameter of the above oxygen generation reaction catalyst may be about 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, and the upper limit may be about 400 nm, 380 nm, 360 nm, 340 nm, 320 nm, 300 nm, 280 nm, 260 nm, 240 nm, 220 nm, 200 nm, 190 nm, 180 nm, 170 nm, 160 nm or 150 nm.

[0073] The diameter of the catalyst for the oxygen generation reaction may be in a range of greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0074] According to another embodiment, the carrier assembly may have the nanowire shape.

[0075] When the above carrier assembly has the nanowire shape, the oxygen generation reaction catalyst of the electrolysis cell including the carrier assembly may have the nanowire shape. When the above carrier assembly has the nanowire shape, the BET specific surface area of ​​the carrier assembly is 150 m 2 / g to 300 m 2 / g can be within the range.

[0076] Figure 2 shows a catalyst (B) for oxygen generation reaction of a water electrolysis cell including a carrier assembly (B) having the above nanowire shape. ') is a schematic diagram showing a carrier assembly (B) having a nanowire shape in which a plurality of nanoparticles (1) are aggregated, and a catalyst (B) for oxygen generation reaction of a water electrolysis cell including a carrier assembly having a nanowire shape in which a plurality of nanoparticles (1) are aggregated and active particles (2) filling the pores of the carrier assembly or supported on the carrier assembly ' ) is shown.

[0077] As illustrated in Fig. 2, a catalyst for oxygen generation reaction including a carrier assembly having a nanowire shape may have a nanowire shape having the same shape as the carrier assembly.

[0078] At this time, the diameter (w) of the oxygen generation reaction catalyst having the nanowire shape r ) and length (w l ) ratio (w) r / w l ) can be within a certain range. The diameter (w) of the catalyst for the oxygen generation reaction r ) and length (w l ) can measure the diameter and length from a photograph of the oxygen evolution reaction catalyst using a scanning electron microscope (SEM). The diameter (w) of the oxygen evolution reaction catalyst r ) and length (w l ) ratio (w) r / w l ) may be about 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2 or 0.25, and its upper limit may be about 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3 or 0.25.

[0079] The ratio of the above oxygen generation reaction catalyst (wr / w l ) may have a range that is greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0080] The diameter of the nanoparticles included in the above carrier aggregate may be within a predetermined range. The diameter of the nanoparticles may be measured by photographing the nanoparticles using a transmission electron microscope (TEM). The diameter may be an average diameter. In this case, the average diameter of the nanoparticles may be calculated by dividing the sum of the diameters of the nanoparticles in the carrier aggregate measured in photographs of the nanoparticles taken using a transmission electron microscope (TEM) by the number of measured nanoparticles.

[0081] For example, the lower limit of the diameter of the nanoparticles may be about 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm, and the upper limit may be about 40 nm, 38 nm, 36 nm, 34 nm, 32 nm, 30 nm, 28 nm, 26 nm, 24 nm, 22 nm, 20 nm, 18 nm, 16 nm, 14 nm, 12 nm, or 10 nm.

[0082] The diameter of the nanoparticles may be greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0083] The above carrier aggregate means a carrier having a structure in which a plurality of nanoparticles are aggregated, and the nanoparticles may include a material that can be commonly used as a carrier.

[0084] In one embodiment, the nanoparticles include a first metal oxide. To distinguish the first metal oxide from the metal oxide included in the carrier aggregate and the metal oxide included in the active particles described below, the metal oxide included in the carrier aggregate is denoted as "first" and the metal oxide included in the active particles is denoted as "second." This notation is merely to help clearly identify the metal oxides included in the carrier aggregate and the active particles, and this order does not indicate a specific priority with respect to their properties.

[0085] The first metal oxide may include tungsten oxide, titanium oxide, nickel oxide, ruthenium oxide, tantalum oxide, tin oxide, cobalt oxide, or a combination thereof.

[0086] For example, the first metal oxide may include titanium dioxide (TiO2).

[0087] The above active particles fill the pores between the nanoparticles of the carrier aggregate having various shapes.

[0088] Additionally, the active particles may fill the pores between the nanoparticles of the carrier assembly or be carried by the carrier assembly and penetrate into the interior thereof. The active particles being carried by the carrier assembly means that the active particles can be carried by at least a portion of the carrier assembly, for example, can be carried in the internal space between a plurality of nanoparticles.

[0089] As illustrated in the right drawings of FIGS. 1 and 2, the active particles may fill the pores of the carrier aggregate in a particle or irregular shape or have a structure supported on the carrier aggregate.

[0090] Since the above active particles have a structure in which they fill the pores formed between the nanoparticles of the carrier aggregate or are supported on the carrier aggregate, the durability of the active particles and the carrier aggregate can be improved by having a stronger bond between the active particles and the carrier aggregate than in a form in which the active particles are simply supported.

[0091] The above active particles may include a second metal oxide different from the first metal oxide. As described above, the designations "first" and "second" in the first metal oxide and the second metal oxide are intended to distinguish the metal oxides included in the carrier aggregate and the active particles, and do not indicate their priority.

[0092] The second metal oxide may include a noble metal oxide.

[0093] For example, the precious metal may be a non-platinum based precious metal, and for example, the non-platinum based precious metal may include palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), alloys thereof, or combinations thereof.

[0094] The above alloys may be, for example, Ir-Fe, Ir-Ru, Ir-Os, Co-Fe, Co-Ru, Co-Os, Rh-Fe, Rh-Ru, Rh-Os, Ir-Ru-Fe, Ir-Ru-Os, Rh-Ru-Fe, Rh-Ru-Os, or combinations thereof.

[0095] In one embodiment, the noble metal oxide is IrO x (wherein x is an integer from 1 to 3), RuO x (where x is an integer from 1 to 3), IrMO x(wherein M includes Ru, Pt, Sn, Se, Sb, Ta, Te, Nb, W, Zn, Au or a combination thereof, and x is an integer from 1 to 3), or a combination thereof. When the active particles include a noble metal oxide as described above, the stability of the oxygen evolution reaction catalyst of the electrolysis cell can be improved due to the excellent stability of the carrier aggregate itself and the strong bonding force with the active particles.

[0096] The above active particles may be included within a predetermined range relative to 100 wt% of the oxygen generation reaction catalyst of the electrolysis cell to fill the pores between the nanoparticles of the carrier assembly or to be supported on the carrier assembly.

[0097] For example, with respect to 100 wt% of the oxygen evolution reaction catalyst of the electrolysis cell, the lower limit of the weight ratio of the active particles may be about 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, or 45 wt%, and the upper limit may be about 70 wt%, 65 wt%, 60 wt%, 55 wt%, 50 wt%, or 45 wt%. The weight ratio of the active particles may be more than or exceeding any one of the lower limits described above; less than or equal to any one of the upper limits described above; or more than or exceeding any one of the lower limits described above and less than or equal to any one of the upper limits described above. That is, the catalyst for the oxygen evolution reaction of the electrolysis cell according to one embodiment may have improved performance, such that the activity of the catalyst is equivalent to or higher than the prior art even when a smaller amount of precious metal is used. Meanwhile, if the content of the active particles is below the above range, the structure that fills the pores formed between the nanoparticles of the carrier aggregate cannot be implemented, so the active particles usually exist in a form supported on the carrier, and thus the durability may be lowered and the activity may be reduced. If the content of the active particles is above the above range, the reaction surface area may be reduced, so that the activity may be reduced.

[0098]

[0099] 2. Method for manufacturing a catalyst for oxygen generation reaction in a water electrolysis cell

[0100] A method for manufacturing a catalyst for oxygen generation reaction of the electrolysis cell according to one embodiment includes forming a carrier aggregate by agglomerating nanoparticles containing a first metal oxide, and filling pores between the nanoparticles of the carrier aggregate with active particles containing a second metal oxide.

[0101] The method for producing a catalyst for oxygen generation reaction of the above-mentioned electrolysis cell may further include producing nanoparticles including a first metal oxide using a first metal oxide precursor. The producing nanoparticles including a first metal oxide using the first metal oxide precursor may be performed before forming a carrier aggregate by agglomerating nanoparticles including a first metal oxide.

[0102] Methods for producing nanoparticles comprising the above first metal oxide are known. For example, known methods for producing metal oxide nanoparticles include wet chemical production methods such as the sol-gel method and hydrothermal synthesis.

[0103] In one embodiment, nanoparticles comprising the first metal oxide may be manufactured using a sol-gel method. For example, the first metal oxide precursor may be added to a predetermined solution, mixed, and then a basic compound may be further added to the mixed solution, followed by mixing at a predetermined temperature, thereby manufacturing the nanoparticles using a sol-gel method.

[0104] The above first metal oxide precursor refers to a material in a previous stage of the first metal oxide, which is the final product included in the oxygen generation reaction catalyst of the electrolysis cell.

[0105] The type of the above first metal oxide is as described in “1. Catalyst for oxygen generation reaction in electrolysis cell.”

[0106] The above first metal oxide may be titanium dioxide (TiO2).

[0107] Accordingly, the type of the first metal oxide precursor is not limited as long as it can produce the final product, titanium dioxide (TiO2).

[0108] For example, the first metal oxide precursor may be titanium alkoxide, TiCl4, Ti(OH)4, or Ti(SO4)2. Specific examples of the titanium alkoxide include titanium ethoxide, titanium butoxide, or titanium isopropoxide. The metal oxide precursor according to one embodiment may be titanium alkoxide.

[0109] The solution may be any solvent capable of dissolving a metal oxide precursor. For example, the solution may include water, alcohol, or a combination thereof. The alcohol may be methanol, ethanol, butanol, or isobutanol.

[0110] The ratio of the first metal oxide precursor mixed in the above solution is not limited, but according to one embodiment, it may be included in an amount of 1 ml% to 10 ml%.

[0111] The above basic compound can be added to appropriately adjust the pH concentration and promote the sol-gel reaction.

[0112] Examples of the basic compounds include ammonium hydroxide, potassium hydroxide, etc., and examples of organic bases include primary amines such as methylamine, ethylamine, isopropylamine, and monoisopropylamine; secondary amines such as diethylamine, diisopropylamine, and dibutylamine; tertiary amines such as trimethylamine, triethylamine, triisopropyramine, and tributylamine; alkanolamines such as tetramethylammonium hydroxide, choline, monoethanolamine, diethanolamine, 2-aminoethanol, 2-(ethylamino)ethanol, 2-(methylamino)ethanol, N-methyl diethanolamine, dimethylaminoethanol, diethylaminoethanol, nitrilotriethanol, 2-(2-amino ethoxy)ethanol, 1-amino-2-propanol, triethanolamine, monopropanolamine, and zibthanoramine.

[0113] In one embodiment, the basic compound may be ammonium hydroxide.

[0114] To control the pH concentration and promote the sol-gel reaction, the content of the basic compound can be appropriately adjusted. For example, the basic compound can be added in the range of 4 ml to 10 ml or 4.5 ml to 9.5 ml per 100 ml of the first metal oxide precursor.

[0115] A sol-gel process can be performed for a predetermined time at a predetermined temperature in a mixed solution in which a basic compound is mixed with the first metal oxide precursor solution.

[0116] For example, the lower limit of the temperature may be about 50°C, 60°C, 70°C, or 80°C, and the upper limit may be about 120°C, 110°C, 100°C, 90°C, or 80°C. In addition, the lower limit of the time may be about 0.5 hours, 1 hour, 1.5 hours, or 2 hours, and the upper limit may be about 3 hours, 2.5 hours, or 2 hours.

[0117] The temperature and time may each be greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0118] Nanoparticles containing the above first metal oxide can be controlled to various sizes and shapes depending on pH, temperature, time, etc. by the sol-gel method.

[0119] According to one embodiment, the diameter of the nanoparticles may be within a predetermined range.

[0120] The lower and upper limits of the diameter of the above nanoparticles are as described in “1. Catalyst for oxygen generation reaction in a water electrolysis cell,” and the range of the diameter of the above nanoparticles is also as described in the above item.

[0121] The above carrier assembly can be manufactured in various forms as described in “1. Catalyst for oxygen generation reaction in electrolysis cell.” For example, the above carrier assembly can be manufactured in the form of a nanosphere or nanowire.

[0122] In order to be manufactured in the above form, it can be manufactured according to a predetermined method.

[0123] In one embodiment, forming a carrier aggregate by agglomerating nanoparticles including the first metal oxide may be accomplished by dispersing nanoparticles including the first metal oxide in a solvent and then agglomerating them to form a carrier aggregate having a nanosphere shape.

[0124] Figure 3 is a scanning electron microscope (SEM) photograph of a carrier assembly having a nanosphere shape manufactured by dispersing nanoparticles containing the first metal oxide in a solvent and then agglomerating them.

[0125] In another embodiment, forming a carrier aggregate by agglomerating nanoparticles including the first metal oxide may be done by filling a mold with nanoparticles including the first metal oxide to form a carrier aggregate having a nanowire shape.

[0126] The type of the above mold is not limited as long as it can form nanowires. For example, the above mold may be a polycarbonate membrane, a nylon membrane, a cellulose membrane, or an anodic aluminum oxide membrane (AAO) having a cylindrical shape.

[0127] In one embodiment, the mold may be an anodic aluminum oxide membrane (AAO membrane).

[0128] Figure 4 is a scanning electron microscope (SEM) photograph of a carrier assembly having a nanowire shape manufactured by filling nanoparticles containing the first metal oxide into an AAO film.

[0129] In addition, according to one embodiment, a method for manufacturing a catalyst for an oxygen generation reaction of an electrolysis cell may perform a heat treatment process on the carrier assembly before agglomerating nanoparticles including the first metal oxide to form a carrier assembly and then filling the pores between the nanoparticles of the carrier assembly with active particles including the second metal oxide. The heat treatment process performed on the carrier assembly before filling the pores between the nanoparticles with the active particles including the second metal oxide is referred to as a "first heat treatment process." The first heat treatment process is intended to be distinguished from a heat treatment process performed to fill the pores between the nanoparticles of the carrier assembly described below with active particles including the second metal oxide, and does not indicate a priority between the heat treatment processes.

[0130] The above first heat treatment process can be performed regardless of the shape of the carrier assembly. That is, it can be performed in both cases where the shape of the carrier assembly is a nanosphere and a nanowire.

[0131] The carrier aggregate after performing the first heat treatment process may have anatase, rutile, brookite or a mixed crystal phase thereof.

[0132] The above first heat treatment process can be performed at a temperature within a predetermined range.

[0133] The lower limit of the first heat treatment temperature may be about 200°C, 250°C, 300°C, 350°C, 400°C, or 500°C, and the upper limit may be about 800°C, 750°C, 700°C, 650°C, 600°C, 550°C, or 500°C. The heat treatment temperature may be higher than or equal to any one of the lower limits described above; lower than or lower than any one of the upper limits described above; or higher than or equal to any one of the lower limits described above and lower than or lower than any one of the upper limits described above.

[0134] By performing the first heat treatment process at a temperature and time within the above-described range, a carrier aggregate having anatase, rutile, brookite or a mixed crystal phase thereof can be formed as described above.

[0135] When the above-described carrier assembly is in the form of a nanowire, a vacuum adsorption process may be performed before the first heat treatment process. The vacuum adsorption process performed before the first heat treatment process is referred to as a "first vacuum adsorption process." The first vacuum adsorption process is intended to be distinguished from the vacuum adsorption process performed to fill the pores between the nanoparticles of the carrier assembly described below with active particles containing a second metal oxide, and does not indicate a priority between the vacuum adsorption processes.

[0136] The above first vacuum adsorption process can be performed by appropriately adjusting the time and pressure as needed. In one embodiment, the time and pressure of the first vacuum adsorption process can be within a predetermined range.

[0137] The lower limit of the time of the first vacuum adsorption process may be about 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes, and the upper limit may be about 90 minutes, 80 minutes, 70 minutes, 60 minutes, 50 minutes, 40 minutes or 30 minutes.

[0138] The lower limit of the pressure of the first vacuum adsorption process may be about 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa or 10 kPa, and the upper limit may be about 20 kPa, 18 kPa, 16 kPa, 14 kPa, 12 kPa or 10 kPa.

[0139] The time and pressure of the first vacuum adsorption process may each have a range of greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0140] By manufacturing carrier aggregates having various shapes as described above, the number of pores through which active particles can penetrate increases, thereby improving the durability of the carrier aggregates and active particles.

[0141] In one embodiment, filling the pores between the nanoparticles of the carrier assembly with active particles including a second metal oxide may include mixing an active particle precursor and a reducing agent in a solution including the carrier assembly to obtain a precursor solution, performing a vacuum adsorption process (hereinafter, “second vacuum adsorption process”) on the precursor solution to adsorb the active particle precursor into the pores between the nanoparticles of the carrier assembly, and performing a heat treatment process (hereinafter, “second heat treatment process”) on the precursor solution that has undergone the vacuum adsorption process.

[0142] The above active particle precursor refers to a material in a previous stage of the active particle, which is the final product.

[0143] The active particle precursor may include a noble metal chloride, a noble metal acetate, a noble metal amine, or a combination thereof. In one embodiment, the active particle precursor may be a noble metal chloride, for example, IrCl4.

[0144] The above reducing agent may include formaldehyde, formic acid, oxalic acid, ascorbic acid, citric acid, urea, ethylenediamine, hexamethylenetetramine, or a combination thereof.

[0145] The weight ratio of the active particle precursor and the reducing agent contained in the precursor solution may be in the range of 1:1 to 1:10.

[0146] The above second vacuum adsorption process refers to a process of adsorbing a substance by lowering the air pressure to create a vacuum state.

[0147] The second vacuum suction can be performed by appropriately adjusting the time and pressure as needed. In one embodiment, the time and pressure of the second vacuum suction can be within a predetermined range.

[0148] For example, the lower limit of the time may be about 5 minutes, 10 minutes, 15 minutes, or 20 minutes, and the upper limit may be about 60 minutes, 50 minutes, 40 minutes, 30 minutes, or 20 minutes. The lower limit of the pressure may be about 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, or 10 kPa, and the upper limit may be about 20 kPa, 18 kPa, 16 kPa, 14 kPa, 12 kPa, or 10 kPa.

[0149] The time and pressure of the second vacuum adsorption process may each have a range of greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0150] A second heat treatment process can be performed on the precursor solution that has undergone the second vacuum adsorption process. Through the heat treatment process, active particles can be formed and stabilized through interactions between the active particle precursor, the weak reducing agent, and the carrier aggregate, and the formation of a catalyst for the oxygen generation reaction of the water electrolysis cell can be induced at an appropriate rate depending on the heat treatment temperature.

[0151] The above second heat treatment process can be performed at a predetermined temperature for a predetermined time.

[0152] For example, the lower limit of the temperature of the second heat treatment process may be about 80°C, 85°C, 90°C, or 100°C, and the upper limit may be about 140°C, 130°C, 120°C, 110°C, or 100°C.

[0153] Additionally, the lower limit of the second heat treatment time may be about 1 hour, 1.5 hours, or 2 hours, and the upper limit may be about 4 hours, 3 hours, or 2 hours.

[0154] The second heat treatment temperature and time may each have a range that is greater than or equal to any one of the lower limits described above; less than or equal to any one of the upper limits described above; or greater than or equal to any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0155]

[0156] 3. Membrane-electrode assembly for electrolysis cell

[0157] A membrane-electrode assembly for a water electrolysis cell according to one embodiment comprises a polymer electrolyte membrane, an oxygen generation electrode positioned on one side of the polymer electrolyte membrane, and a hydrogen generation electrode positioned on the other side of the polymer electrolyte membrane.

[0158] The membrane-electrode assembly for the above-described electrolysis cell is illustrated in FIG. 3. The membrane-electrode assembly (100) for the electrolysis cell according to FIG. 3 includes a polymer electrolyte membrane (30); an oxygen generation electrode (10) positioned on one side of the polymer electrolyte membrane; and a hydrogen generation electrode (20) positioned on the other side of the polymer electrolyte membrane.

[0159] The membrane-electrode assembly for the above-mentioned electrolysis cell can have excellent durability by including the above-mentioned oxygen evolution reaction catalyst.

[0160] For example, the durability of a membrane-electrode assembly can be expressed by a voltage increase rate. The voltage increase rate of the membrane-electrode assembly including the oxygen evolution reaction catalyst, as expressed by Equation 1 below, can be within a predetermined range. A specific method for measuring the voltage increase rate follows the method described in "Durability Evaluation" in Evaluation Example 3 of this specification.

[0161] [Formula 1]

[0162] Voltage increase rate (%) = (voltage after driving - initial voltage) / (initial voltage) × 100

[0163] The lower limit of the voltage increase rate may be about 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6% or 1.7%, and the upper limit may be about 3%, 2.5%, 2%, 1.9%, 1.8%, 1.7%, 1.6%, 1.5%, 1.4% or 1.3%.

[0164] The voltage increase rate of the membrane-electrode assembly may have a range that is less than or equal to any one of the upper limits described above; or greater than or exceeding any one of the lower limits described above, and less than or equal to any one of the upper limits described above.

[0165] Hereinafter, the oxygen generation electrode, the hydrogen generation electrode, and the polymer electrolyte membrane will be described in detail.

[0166] The above oxygen evolution electrode refers to an electrode where an oxygen evolution reaction (OER) occurs.

[0167] The above oxygen generation electrode includes a catalyst for the oxygen generation reaction of the water electrolysis cell.

[0168] The catalyst for the oxygen generation reaction of the above electrolysis cell is the same as that described in the item “1. Catalyst for the oxygen generation reaction of the electrolysis cell.”

[0169] The above oxygen generation electrode may include an oxygen generation reaction catalyst within a predetermined range with respect to 100 wt% of the oxygen generation electrode.

[0170] For example, the lower limit of the content of the catalyst for the oxygen generation reaction may be about 65 wt% or 67 wt%, and the upper limit may be about 90 wt% or 95 wt%.

[0171] The content of the catalyst for the oxygen generation reaction may be in a range of more than or exceeding any one of the lower limits described above; less than or equal to any one of the upper limits described above; or more than or exceeding any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0172] The above oxygen generation electrode may further include an ion conductor to improve the adhesion of the catalyst and transfer hydrogen ions.

[0173] The above ion conductor may include a cation exchanger to ensure ion conductivity.

[0174] The above cation exchanger may be a sulfonic acid group, a carboxyl group, a boronic acid group, a phosphoric acid group, a phosphonic acid group, an imide group, a sulfonimide group, a sulfonamide group, or a sulfonic acid fluoride.

[0175] The above ion conductor may be a fluorine-based ion conductor, a hydrocarbon-based ion conductor, or a mixture thereof.

[0176] The above fluorine-based ion conductor may be a fluorine-based polymer having the cation exchange group in the side chain and containing fluorine in the main chain, for example, poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), etc.

[0177] The hydrocarbon-based ion conductor is a hydrocarbon-based polymer having the cation exchange group in the side chain [e.g., sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated polyquinoxaline, sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyether sulfone, Sulfonated polyether ketone, sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyarylene ether nitrile, sulfonated polyarylene ether ether nitrile,It may be polyarylene ether sulfone ketone, etc.

[0178] According to one embodiment, the ion conductor may have hydrogen ion conductivity.

[0179] The ion conductor having the above hydrogen ion conductivity can also substitute H with Na, K, Li, Cs or tetrabutylammonium in the cation exchanger at the end of the side chain. When substituting H with Na in the ion exchanger at the end of the side chain, NaOH is used during the preparation of the catalyst composition, and when substituting H with tetrabutylammonium, tetrabutylammonium hydroxide is used. K, Li or Cs can also be substituted using an appropriate compound. Since this substitution method is widely known in the art, a detailed description thereof will be omitted herein.

[0180] The content of the above ion conductor can be appropriately adjusted as needed. In one example, the lower limit of the content of the above ion conductor relative to 100 parts by weight of the oxygen generation reaction catalyst can be about 65 parts by weight or 68 parts by weight, and the upper limit can be about 95 parts by weight or 90 parts by weight.

[0181] The ion conductor may have a range of at least or exceeding any one of the lower limits described above, relative to 100 parts by weight of the oxygen evolution reaction catalyst; or at most or exceeding any one of the upper limits described above, or at most or exceeding any one of the lower limits described above, and at most or less than any one of the upper limits described above. When the ion conductor is within the above range, the performance and durability are excellent.

[0182] The above ion conductor can be used as a single substance or as a mixture, and may also be optionally used together with a non-conductive compound to further enhance adhesion to the polymer electrolyte membrane. The content of the non-conductive compound can be appropriately adjusted depending on the intended use.

[0183] As the above non-conductive compound, at least one selected from polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene (ETFE), ethylene chlorotrifluoro-ethylene copolymer (ECTFE), polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), dodecylbenzenesulfonic acid, and sorbitol can be used.

[0184] The above hydrogen generation electrode refers to an electrode where a hydrogen evolution reaction (Hydrogen Evolution Reaction (HER)) occurs.

[0185] The above hydrogen generation electrode may include a catalyst for hydrogen generation reaction. The catalyst for hydrogen generation reaction may include active particles and a carrier.

[0186] The above active particles may include a precious metal.

[0187] For example, the precious metal may be a platinum-based precious metal.

[0188] The platinum-based precious metal may be platinum (Pt) and / or a Pt-M alloy. The M may be palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), zinc (Zn), tin (Sn), molybdenum (Mo), tungsten (W), lanthanum (La), or rhodium (Rh).

[0189] Specifically, the Pt-M alloy includes Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ni, Pt-Co, Pt-Y, Pt-Ru-W, Pt-Ru-Ni, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Ru-Ir-Ni, Pt-Co-Mn, Pt-Co-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe, Pt-Fe-Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni, Pt-Ni-Ir, Pt-Cr, Pt-Cr-Ir, or these Mixtures can be used.

[0190] The above carrier may be a carbon-based carrier.

[0191] The carbon-based carrier may be graphite, super P, carbon fiber, carbon sheet, carbon black, Ketjen Black, Denka black, acetylene black, carbon nanotube (CNT), carbon sphere, carbon ribbon, fullerene, activated carbon, carbon nanofiber, carbon nanowire, carbon nanoball, carbon nanohorn, carbon nanocage, carbon nanoring, ordered nano- / meso-porous carbon, carbon aerogel, mesoporous carbon, graphene, stabilized carbon, activated carbon, or a combination thereof.

[0192] The above oxygen generation electrode and the above hydrogen generation electrode may each include only a catalyst layer including an oxygen generation reaction catalyst and a hydrogen generation reaction catalyst, but may include an electrode substrate together with the catalyst layer.

[0193] At this time, the electrode substrate can play a role in supporting the electrode and diffusing the fuel and oxidant to the catalyst layer.

[0194] The electrode substrate may include a microporous layer, a porous diffusion layer, or a combination thereof.

[0195] The above microporous layer serves to enhance the diffusion effect of the reactant, and may generally include a conductive powder having a small particle size, for example, carbon powder, carbon black, acetylene black, activated carbon, metal oxide nanowire, carbon fiber, fullerene, carbon nanotube, carbon nanowire, carbon nano-horn, or carbon nano ring.

[0196] The above porous diffusion layer is made of porous titanium, carbon paper, carbon cloth, carbon felt or metal cloth (a porous film made of metal cloth in a fibrous state or a metal film formed on the surface of a cloth formed of polymer fibers).

[0197] The above microporous layer and the above porous diffusion layer may include known materials in addition to those exemplified above.

[0198] The above electrode substrate can be treated with a water-repellent fluorine resin, in which case the diffusion efficiency of reactants can be prevented from being reduced by water generated during operation of the electrolysis cell.

[0199] As the above fluorine-based resin, polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxy vinyl ether, fluorinated ethylene propylene, polychlorotrifluoroethylene or a copolymer thereof can be used.

[0200] The above electrode substrate can improve conductivity by using platinum or the like and prevent corrosion of the porous diffusion layer by an ion conductor, thereby preventing deterioration of electrolysis performance.

[0201] The above polymer electrolyte membrane has an ion exchange function that moves hydrogen ions generated at an oxygen generation electrode to a catalyst for hydrogen generation reaction.

[0202] A polymer electrolyte membrane according to one embodiment may include a porous support including a plurality of pores, and an ion conductor filling the pores of the porous support.

[0203] The above porous support may be a fluorine-based support or a nano web support.

[0204] The above fluorine-based support may correspond to, for example, expanded polytetrafluoroethylene (e-PTFE) having a microstructure of polymer fibrils or a microstructure in which nodes are interconnected by fibrils.

[0205] The above nano web support may be a support in which nano fibers are integrated in the form of a non-woven fabric containing a large number of pores.

[0206] The above ion conductor is as described above.

[0207] The ion conductor included in the polymer electrolyte membrane may be the same as or different from the ion conductor included in the oxygen generation electrode. For example, the ion conductor included in the polymer electrolyte membrane may be the same as the ion conductor included in the oxygen generation electrode.

[0208]

[0209] 4. Susan Hae-cell

[0210] In one embodiment, the electrolysis cell comprises a membrane-electrode assembly for the electrolysis cell.

[0211] The above electrolytic cell is the same as the known one except that it includes a membrane-electrode assembly according to the present application, and therefore a detailed description thereof is omitted.

[0212] Hereinafter, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

[0213] Manufacturing Example 1. Preparation of nanoparticle solution

[0214] As a solution, 100 ml of a mixed solution of ethanol and water (H2O) in a ratio of 1:1 (=ethanol:water) was placed in a reaction vessel, and 3 ml of Ti-butoxide from Sigma-Aldrich was added as a first metal oxide precursor to prepare a first mixture.

[0215] To adjust the pH concentration of the first mixture, 0.2 ml of 0.2 M Sigma-Aldrich ammonium hydroxide (NH4OH) as a basic compound was added to prepare a second mixture.

[0216] The above second mixture was subjected to a sol-gel process at 80°C for 2 hours to produce TiO2. A plurality of nanoparticles including were formed.

[0217] At this time, the average diameter of the nanoparticles was 10 nm as calculated by taking pictures and measuring them using a transmission electron microscope (TEM).

[0218]

[0219] Manufacturing Example 2-1. Manufacturing of nanosphere-shaped carrier aggregates

[0220] The solution according to Manufacturing Example 1 was dried at 80°C for 3 hours, dispersed in 100 ml of a mixed solution of ethanol and water (H2O) in a ratio of 2:1 (=ethanol:water), and dried at 70°C for 2 hours. Thereafter, a first heat treatment was performed at 500°C in air for 1 hour, thereby producing a carrier aggregate having a nanosphere shape as shown in the left scanning electron microscope (SEM) image of Fig. 4.

[0221] At this time, the BET surface area of ​​the carrier aggregate is 202 m 2 It was around / g.

[0222]

[0223] Manufacturing Example 2-2. Manufacturing of nanowire-shaped carrier aggregates

[0224] The solution according to Manufacturing Example 1 was charged into an Anodic Aluminum Oxide membrane (Whatman, Anodisc), and the first vacuum adsorption process was performed for 30 minutes under a pressure of 10 kPa, followed by drying.

[0225] Afterwards, the first heat treatment was performed at 500℃ and in air for 1 hour, and the anodic aluminum oxide membrane was removed, thereby manufacturing a carrier assembly having a nanowire shape as shown in the left scanning electron microscope (SEM) image of Fig. 5.

[0226] At this time, the BET surface area of ​​the carrier aggregate is 235 m 2 It was around / g.

[0227]

[0228] Example 1

[0229] After placing 1.0 g of the carrier aggregate formed according to Manufacturing Example 2-1 into a reaction vessel, a precursor solution was prepared by adding IrCl4 from Sigma-Aldrich as an active particle precursor and oxalic acid from Sigma-Aldrich as a weak reducing agent to a mixed solution of ethanol:water (H2O) in a 1:1 ratio.

[0230] The above precursor solution was subjected to a second vacuum adsorption process at a pressure of 10 kPa in a vacuum for 20 minutes, so that the active particle precursor filled the pores of the carrier aggregate or was supported on the carrier aggregate and penetrated into the interior to be adsorbed.

[0231] In addition, the precursor solution that underwent the above vacuum adsorption process was subjected to a second heat treatment at 100°C for 2 hours to form IrO in the carrier aggregate. x A catalyst for oxygen generation reaction in a water electrolysis cell was prepared.

[0232] The content of active particles was approximately 45 wt% for 100 wt% of the oxygen generation reaction catalyst of the above electrolysis cell.

[0233] The right photo of Fig. 4 shows IrO X- A scanning electron microscope (SEM) image of a catalyst for oxygen evolution reaction formed by filling the pores of the carrier assembly or being supported on the carrier assembly and penetrating into the interior is shown.

[0234] As shown in the right-hand photo of Fig. 4, the oxygen evolution reaction catalyst of the electrolysis cell manufactured in Example 1 has a nanosphere shape identical to the shape of the carrier aggregate, and the diameter of the oxygen evolution reaction catalyst was measured using a scanning electron microscope (SEM) to be approximately 150 nm.

[0235] As shown in the results of Fig. 7, the BET specific surface area of ​​the oxygen generation reaction catalyst of the electrolysis cell is 105 m 2 / g. The BET specific surface area of ​​the carrier aggregate manufactured according to Manufacturing Example 2-1 was 202 m 2 Considering that the mass is about / g, it can be confirmed that the active particles fill the pores of the carrier aggregate.

[0236]

[0237] Example 2

[0238] A catalyst for oxygen generation reaction was manufactured in the same manner as in Example 1, except that the carrier aggregate formed according to Manufacturing Example 2-2 was applied.

[0239] The content of active particles was approximately 45 wt% for 100 wt% of the oxygen generation reaction catalyst of the above electrolysis cell.

[0240] The right photo of Fig. 5 shows IrO X A scanning electron microscope (SEM) image of a catalyst for oxygen evolution reaction formed by filling the pores of a carrier assembly or being supported on and penetrating into the carrier assembly is shown.

[0241] As shown in the right picture of Fig. 5, the oxygen generation reaction catalyst of the electrolysis cell manufactured in Example 2 has a nanowire shape identical to the shape of the carrier assembly, and the diameter (w) of the catalystr ) and height (w l ) was measured in the photograph of the oxygen evolution reaction catalyst using a scanning electron microscope (SEM), and the diameter (w) was measured. r ) and length (w l ) ratio (w) r / w l ) was about 0.25 when calculating.

[0242] As shown in the results of Fig. 7, the BET specific surface area of ​​the oxygen generation reaction catalyst of the electrolysis cell is 138 m 2 / g. The BET specific surface area of ​​the carrier aggregate manufactured according to Manufacturing Example 2-2 was 235 m 2 Considering that the mass is about / g, it can be confirmed that the active particles fill the pores of the carrier aggregate.

[0243]

[0244] Comparative Example 1

[0245] As a catalyst for the oxygen evolution reaction, only a commercial IrO2 (Alfa Aesar, 43396) catalyst was used without including a carrier assembly.

[0246]

[0247] Comparative Example 2

[0248] A precursor solution was prepared by dissolving IrCl4 as an active particle precursor in a mixed solution of isopropanol and 37% hydrochloric acid (HCl) in a 1:1 ratio (=isopropanol:hydrochloric acid).

[0249] The precursor solution was repeatedly coated on an AAO membrane (Anodic Aluminum Oxide membrane) to grow IrO2, thereby producing a catalyst in the form of a nanowire.

[0250]

[0251] Comparative Example 3

[0252] As a catalyst for the oxygen evolution reaction, a commercial IrO2 / TiO2 catalyst from Heraeus supported on a carrier was used.

[0253] A transmission electron microscope (TEM) image of the oxygen evolution reaction catalyst is shown in Fig. 6. According to Fig. 7, the oxygen evolution reaction catalyst includes active particles and a carrier that supports the active particles, and unlike Examples 1 and 2, the carrier does not have a nanosphere or nanowire shape.

[0254] The BET specific surface area of ​​the above oxygen generation reaction catalyst is 105 m 2 It was around / g.

[0255]

[0256] Evaluation Example 1. BET Surface Area Analysis

[0257] The BET specific surface area of ​​the carrier assembly manufactured in Manufacturing Examples 2-1 and 2-2 and the oxygen generation reaction catalyst manufactured in Examples 1 and 2 including the carrier assembly of Manufacturing Examples 2-1 and 2-2 was measured according to a nitrogen adsorption experiment method.

[0258] Nitrogen adsorption measurements were performed using a static volumetric apparatus (Micromeritics, ASAP-2020) at a temperature of 77 K, and the results are shown in Fig. 7.

[0259]

[0260] Evaluation Example 2. IV Characteristics

[0261] An electrode slurry was prepared by adding 20 parts by weight of an ion conductor dispersion and a solvent to 100 parts by weight of the oxygen evolution reaction catalyst of the electrolysis cell manufactured in Examples 1 and 2 and Comparative Examples 1 to 3, and the electrode slurry was directly coated on a polymer electrolyte membrane (Chemours, NR212) and then dried at 90°C for 30 minutes to prepare a membrane-electrode assembly for an electrolysis cell.

[0262] The membrane-electrode assembly for the electrolysis cell manufactured above was applied inside a unit cell designed and manufactured for the electrolysis cell, and the voltage and resistance were measured at specific currents from 1 mA to 20 A under conditions of a cell temperature of 80°C, a water temperature of 80°C, and a flow rate of 5 ml / min using a protocol for measuring the voltage and resistance, and the measurement was stopped at 2 V.

[0263] The result at this time is as shown in Fig. 8.

[0264]

[0265] Evaluation Example 3. Durability Evaluation

[0266] A membrane-electrode assembly was manufactured in the same manner as in Evaluation Example 1, and the manufactured membrane-electrode assembly was applied inside a unit cell designed and manufactured for a water electrolysis cell, at a cell temperature of 80°C and a current density of 1 A / cm. 2 After driving the constant current for 500 hours, the voltage increase rate was measured.

[0267] The above voltage increase rate was measured using a potentiostat device from BioLogic and calculated according to Equation 1 below. The results are shown in Table 1 below.

[0268] [Formula 1]

[0269] Voltage increase rate (%) = (voltage after operation - initial voltage) / (initial voltage) × 100

[0270] Voltage increase rate (%) Example 11.7 Example 21.3 Comparative example 17.8 Comparative example 26.3 Comparative example 33.5

[0271]

[0272] result

[0273] Referring to the graph of Fig. 7, the specific surface area of ​​the oxygen evolution reaction catalyst manufactured according to Examples 1 and 2 including the carrier aggregate manufactured according to Manufacturing Examples 2-1 and 2-2 decreases compared to the specific surface area of ​​the carrier aggregate manufactured according to Manufacturing Examples 2-1 and 2-2. Through this, it can be confirmed that the oxygen evolution reaction catalyst manufactured according to Examples 1 and 2 has active particles that fill the pores of the carrier aggregate or are supported on the carrier aggregate and penetrate the interior.

[0274] Referring to the graph of FIG. 8, it can be confirmed that the membrane-electrode assembly including the oxygen evolution reaction catalyst of the electrolysis cell of Examples 1 and 2, which includes a nanosphere or nanowire-shaped carrier assembly, exhibits improved performance by showing a higher current density at the same voltage compared to the membrane-electrode assembly including the oxygen evolution reaction catalyst of the electrolysis cell of Comparative Examples 1 and 2, which does not include a carrier.

[0275] According to the durability evaluation, it can be confirmed that the membrane-electrode assembly including the oxygen evolution reaction catalyst of the water electrolysis cell of Examples 1 and 2 including the carrier assembly having a nanosphere or nanowire shape has an increased durability with a reduced voltage increase rate compared to the membrane-electrode assembly including the oxygen evolution reaction catalyst of the water electrolysis cell of Comparative Examples 1 and 2 not including a carrier. In addition, it can be confirmed that the membrane-electrode assembly including the oxygen evolution reaction catalyst of the water electrolysis cell of Examples 1 and 2 including the carrier assembly having a nanosphere or nanowire shape has an increased durability with a reduced voltage increase rate compared to the membrane-electrode assembly of Comparative Example 3 using a commercial IrO2 / TiO2 catalyst from Heraeus supported on the carrier, unlike the carrier assembly having a nanosphere or nanowire shape.

[0276]

[0277] Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure defined in the following claims also fall within the scope of the present disclosure.

[0278] [Explanation of symbols]

[0279] 1: Nanoparticles

[0280] 2: Active particles

[0281] A: A carrier assembly having a nanosphere shape

[0282] A ' : Catalyst for oxygen evolution reaction comprising a carrier assembly having a nanosphere shape

[0283] B: Carrier assembly with nanowire shape

[0284] B ' : Catalyst for oxygen evolution reaction comprising a carrier assembly having a nanowire shape

[0285] 100: Membrane-electrode assembly for electrolysis cell

[0286] 10: Oxygen generation electrode

[0287] 20: Hydrogen generation electrode

[0288] 30: Polymer electrolyte membrane

Claims

1. A carrier aggregate in which multiple nanoparticles are aggregated; and including active particles filling the pores between the nanoparticles of the carrier assembly or supported on the carrier assembly; The above nanoparticles comprise a first metal oxide, The above active particles include a second metal oxide different from the first metal oxide, Catalyst for oxygen evolution reaction in a water electrolysis cell.

2. In paragraph 1, The BET surface area of ​​the above carrier aggregate is 100 m 2 / g to 300 m 2 Within the range of / g, Catalyst for oxygen evolution reaction in a water electrolysis cell.

3. In paragraph 1, The above carrier assembly has a nanosphere or nanowire shape. Catalyst for oxygen evolution reaction in a water electrolysis cell.

4. In paragraph 3, When the above carrier aggregate has the nanosphere shape, The oxygen generation reaction catalyst of the above-mentioned electrolysis cell also has a nanosphere shape. The diameter of the above catalyst is in the range of 40 nm to 400 nm. Catalyst for oxygen evolution reaction in a water electrolysis cell.

5. In paragraph 3, When the above carrier assembly has the nanowire shape, The oxygen generation reaction catalyst of the above-mentioned electrolysis cell also has a nanowire shape. Diameter of the above catalyst (w r ) and length (w l ) ratio (w) r / w l ) is in the range of 0.05 to 0.9, Catalyst for oxygen evolution reaction in a water electrolysis cell.

6. In paragraph 1, The diameter of the above nanoparticles is in the range of 2 nm to 40 nm. Catalyst for oxygen evolution reaction in a water electrolysis cell.

7. In paragraph 1, The above first metal oxide comprises titanium dioxide (TiO2). Catalyst for oxygen evolution reaction in a water electrolysis cell.

8. In paragraph 1, The second metal oxide comprises a noble metal oxide, The above precious metal oxide is IrO x (wherein x is an integer from 1 to 3), RuO x (where x is an integer from 1 to 3), IrMO x (wherein M comprises Ru, Pt, Sn, Se, Sb, Ta, Te, Nb, W, Zn, Au, or a combination thereof, and x is an integer from 1 to 3), or a combination thereof, Catalyst for oxygen evolution reaction in a water electrolysis cell.

9. In paragraph 1, The active particles are included in an amount of 20 wt% to 70 wt% based on 100 wt% of the oxygen generation reaction catalyst. Catalyst for oxygen evolution reaction in electrolysis cells.

10. Agglomerating nanoparticles containing the first metal oxide to form a carrier aggregate, Comprising filling the pores between the nanoparticles of the carrier assembly with active particles comprising a second metal oxide, A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell.

11. In paragraph 10, Further comprising manufacturing nanoparticles comprising the first metal oxide using a first metal oxide precursor, The first metal oxide precursor comprises titanium alkoxide, TiCl4, Ti(OH)4, Ti(SO4)2, or a combination thereof. A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell.

12. In paragraph 11, Forming a carrier aggregate by agglomerating nanoparticles containing the first metal oxide is as follows. Dispersing nanoparticles containing the first metal oxide in a solvent and then coagulating them to form a carrier aggregate having a nanosphere shape; or A method of forming a carrier assembly having a nanowire shape by filling a mold with nanoparticles containing the first metal oxide, A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell.

13. In paragraph 10, Filling the pores between the nanoparticles of the carrier aggregate with the active particles including the second metal oxide, A precursor solution is obtained by mixing an active particle precursor and a reducing agent in a weight ratio within the range of 1:1 to 1:10 in a solution containing the above carrier aggregate, By performing a vacuum adsorption process on the precursor solution, the active particle precursor is adsorbed into the pores between the nanoparticles of the carrier aggregate, and Including performing a heat treatment process on a precursor solution after performing the above vacuum adsorption process, The above active particle precursor comprises a noble metal chloride, a noble metal acetate, a noble metal amine, or a combination thereof, The above reducing agent comprises formaldehyde, formic acid, oxalic acid, ascorbic acid, citric acid, urea, ethylenediamine, hexamethylenetetramine, or a mixture thereof. A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell.

14. In paragraph 13, A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell, wherein the above vacuum adsorption is performed at 5 kPa to 20 kPa.

15. In paragraph 13, A method for producing a catalyst for oxygen generation reaction in a water electrolysis cell, wherein the above heat treatment process is performed at a temperature of 80°C to 140°C for 1 to 4 hours.

16. Polymer electrolyte membrane; An oxygen generation electrode positioned on one side of the polymer electrolyte membrane and including an oxygen generation reaction catalyst and an ion conductor of the water electrolysis cell according to claim 1; and A hydrogen generation electrode, which is located on the other side of the polymer electrolyte membrane and includes a carbon-based carrier and active particles supported on the carbon-based carrier and including a noble metal; Membrane-electrode assembly for a hydroelectric cell.

17. In paragraph 16, The voltage increase rate expressed by Equation 1 below is 3% or less, Membrane-electrode assembly for water electrolysis cell: [Formula 1] Voltage increase rate (%) = (voltage after driving - initial voltage) / (initial voltage) × 100 18. In paragraph 16, The above oxygen generation electrode contains the oxygen generation reaction catalyst in the range of 65 wt% to 95 wt% based on 100 wt% of the oxygen generation electrode. Membrane-electrode assembly for a hydroelectric cell.

19. In Article 16, The above polymer electrolyte membrane is a membrane-electrode assembly for a water electrolysis cell including a porous support including a plurality of pores, and an ion conductor filling the pores of the porous support.

20. A water electrolysis cell comprising a membrane electrode assembly according to claim 16.

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