Electrode catalyst for polymer electrolyte membrane water electrolysis, preparation method therefor, electrode for polymer electrolyte membrane water electrolysis comprising same, and polymer electrolyte membrane water electrolysis cell comprising same

Abstract

Provided are a novel electrode catalyst for polymer electrolyte membrane water electrolysis having improved oxygenevolutionreaction (OER) activity and durability, a method of preparing the same, an electrode for polymer electrolyte membrane water electrolysis including the same, and a polymer electrolyte membrane water electrolysis cell including the same.SOLUTION: The present disclosure provides an electrode catalyst for PolymerElectrolyteMembrane (PEM) water electrolysis including an iridium-based catalyst, wherein the iridium-based catalyst is a core-shell particle, the core includes iridium metal, and the shell includes an iridium-tin composite oxide, a method for preparing the same, an electrode for PEM water electrolysis including the electrode catalyst, and a cell for PEM water electrolysis including the same. The electrode catalyst for PEM water electrolysis has improved dispersibility and durability. An electrode including such an electrode catalyst has improved OER activity.SELECTED DRAWING: Figure 3

Description

Detailed Description of the Invention

[0001] [Technical field] The present invention relates to an electrode catalyst for polymer electrolyte membrane (PEM) water electrolysis, a method for producing the same, an electrode for PEM water electrolysis including the same, and a PEM water electrolysis cell including the same.

[0002] The national research and development projects that supported this invention are as follows:

[0003] Project unique number: 1415186363 Project number: 20020437 Ministry in charge: Ministry of Trade, Industry and Energy Issue management organization: Korea Institute for Industrial Technology Evaluation and Management Research project name: Development of innovative nano-fusion product technology Research title: Development of hydrogen electric vehicle fuel cell module technology based on platinum alloy nanocatalyst production with MEA platinum usage of less than 0.2gkW Project execution organization: The Carbon Studio Co., Ltd. Research period: January 1, 2023 to December 31, 2025 Project unique number: 1415185115 Project number: 20022451 Ministry in charge: Ministry of Trade, Industry and Energy Issue management organization: Korea Institute for Industrial Technology Evaluation and Management Research project name: Development of material component technology - package type Research topic: Development of PEM water electrolysis membrane / catalyst production technology Project execution organization: Chemtros Co., Ltd. Research period: January 1, 2023 to December 31, 2025 [Background technology] Research and development into a new type of energy storage system is currently underway, in which electrical energy produced by renewable energy sources such as solar, wind, and tidal power is converted into hydrogen obtained by electrolysis of water and stored. When an energy source is needed, the stored hydrogen is supplied to a fuel cell and used as electrical energy.

[0004] Water electrolysis technology, one of the various hydrogen production methods, can be divided into alkaline, solid oxide, and polymer electrolyte membrane (PEM) water electrolysis. Among them, PEM water electrolysis technology operates at a relatively low temperature and uses pure water without any corrosive solution inside, so it has economic advantages over other water electrolysis methods, as it has higher hydrogen production efficiency and can produce highly pure hydrogen.

[0005] One of the key components in PEM water electrolysis is the development of catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which occur in the membrane electrode assembly (MEA). In particular, oxygen overvoltage has a significant impact on efficiency reduction in the water electrolysis reaction, so the development of a new catalyst that can reduce the overvoltage of the oxygen evolution catalyst is essential for commercialization.

[0006] Iridium oxide (IrO2), currently used as a typical OER catalyst, differs in activity and durability depending on the arrangement of oxygen atoms. Amorphous iridium oxide, with its irregular arrangement of oxygen atoms, has excellent catalytic performance, but because PEM water electrolysis operates in an acidic atmosphere, some of the iridium dissolves in water, reducing durability. Crystalline iridium oxide is produced at high temperatures, reducing the dispersion of the support, resulting in low catalytic activity but excellent durability. To achieve both high catalytic activity and durability, a new catalytic structure of IrO2 with high dispersion on the support, small particle size, and high crystallinity must be developed.

[0007] Furthermore, conventional catalysts have not been developed with the technology to satisfy both the two elements of reducing the physical particle size and increasing the crystallinity of iridium oxide through alloying, and therefore the activity and durability cannot reach satisfactory levels, and improvements in this area are required.

[0008] [Summary of the Invention] [Problem to be solved by the invention] An object of the present invention is to provide a novel polymer electrolyte membrane electrode catalyst for water electrolysis that has improved oxygen evolution reaction (OER) activity and durability.

[0009] Another object of the present invention is to provide a method for producing the above-mentioned electrode catalyst for polymer electrolyte membrane water electrolysis.

[0010] A further object of the present invention is to provide a polymer electrolyte membrane (PEM) water electrolysis electrode including the above-mentioned electrode catalyst for water electrolysis, and a PEM water electrolysis cell including the same.

[0011] [Means for solving the problem] To achieve the above object, a polymer electrolyte membrane (PEM) water electrolysis electrode catalyst containing an iridium-based catalyst is provided, The iridium-based catalyst is a core-shell particle, the core comprises iridium metal; The shell contains an iridium tin composite oxide, and an electrode catalyst for polymer electrolyte membrane (PEM) water electrolysis is provided.

[0012] To achieve another object, a step of dispersing a carrier in a polyol to prepare a carrier dispersion; mixing an iridium precursor and a tin precursor with a polyol to obtain a precursor mixture; mixing the carrier dispersion and a precursor mixture to form a first mixture; performing a first heat treatment of the first mixture to produce a catalyst precursor comprising iridium metal and tin oxide particles; and washing and drying the catalyst precursor, and then performing a second heat treatment under an oxidizing gas atmosphere, thereby producing the above-mentioned polymer electrolyte membrane (PEM) electrode catalyst for water electrolysis; The method for producing an electrode catalyst for PEM water electrolysis is provided, wherein the mixing molar ratio of the iridium precursor to the tin precursor is 1:0.33 to 0.50.

[0013] The first heat treatment is performed at a temperature of 200 to 550° C. The oxidizing gas atmosphere is, for example, an air atmosphere, an oxygen gas atmosphere, or a combination thereof. The second heat treatment can be performed at a temperature of 350 to 600° C., which is higher than that of the first heat treatment.

[0014] To achieve another object, there is provided a polymer electrolyte membrane (PEM) water electrolysis cell including a PEM water electrolysis electrode containing the above-mentioned PEM water electrolysis electrode catalyst.

[0015] To achieve another object, a polymer electrolyte membrane and There is provided a PEM water electrolysis cell including a PEM water electrolysis electrode located on one side of the polymer electrolyte membrane and including the above-mentioned PEM water electrolysis electrode catalyst.

[0016] The electrode may include an anode.

[0017] [Effects of the invention] The electrode catalyst for PEM water electrolysis according to the present invention has improved dispersibility and durability. A PEM water electrolysis electrode containing such an electrode catalyst has improved oxygen evolution reaction (OER) activity. The use of such a water electrolysis electrode makes it possible to produce a PEM water electrolysis cell with improved cell performance.

[0018] However, the effects of the present invention are not limited to these and may include effects that are expected from the technical features of the present invention, even if not directly described below.

[0019] [Brief description of the drawing] FIG. 1 is a diagram schematically illustrating the core-shell structure of a polymer electrolyte membrane (PEM) water electrolysis electrode catalyst according to the present invention. FIG. 2 is a flowchart illustrating a method for producing an electrode catalyst for PEM water electrolysis according to the present invention. FIG. 3 is a diagram showing X-ray diffraction analysis spectra of the catalysts according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2. 4a and 4b are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Example 1, respectively. 4c and 4d are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Example 2, respectively. 5a and 5b are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Comparative Example 1, respectively. 5c and 5d are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Comparative Example 2, respectively. 6 is a graph showing voltage changes with current density in PEM water electrolysis cells equipped with electrodes containing the electrode catalysts according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

[0033] FIG. FIG. 7 is a diagram schematically illustrating the structure of a water electrolysis cell having a membrane electrode assembly for PEM water electrolysis of the present invention.

[0020] [Mode for Carrying Out the Invention] Hereinafter, a polymer electrolyte membrane (PEM) water electrolysis electrode catalyst according to one embodiment, a method for producing the same, a PEM water electrolysis electrode including the same, and a PEM water electrolysis cell including the same will be described.

[0021] This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0022] In this disclosure, the term "average particle size" refers to "D50," which is the particle size corresponding to 50% of the smallest particles when the total number of particles is 100% in a distribution curve obtained by accumulating particle sizes from the smallest to the largest. D50 can be measured by methods well known to those skilled in the art, for example, using a particle size analyzer or from transmission electron microscopy (TEM) or SEM images. Another example of a method for measuring the average particle size is to measure using a measuring device using dynamic light scattering, and then perform data analysis to count the number of particles in each size range, from which the average particle size can be easily calculated.

[0023] The average particle size in the present disclosure can be measured using a scanning electron microscope or a transmission electron microscope.

[0024] The polymer electrolyte membrane (PEM) electrode catalyst for water electrolysis of the present invention includes an iridium-based catalyst, and the iridium-based catalyst is a core-shell particle, the core including iridium metal, and the shell including iridium-tin composite oxide.

[0025] PEM water electrolysis generates hydrogen and oxygen through oxidation and reduction using electrical energy, as shown in Schemes 1 and 2 below.

[0026] <Scheme 1> Cathode: 4H + +4e - →2H2 <Scheme 2> Anode: 2H2O → O2 + 4H + +4e - According to Scheme 1, H generated at the anode + Ions migrate through a polymer electrolyte membrane (PEM) to the cathode.

[0027] The electrode catalyst for PEM water electrolysis of the present invention is an oxygen evolution reaction catalyst for PEM water electrolysis, and contains iridium metal in the core and iridium tin composite oxide in the shell. The iridium tin composite oxide can also be named iridium oxide-tin oxide (IrSnO2) alloy.

[0028] The electrode catalyst for PEM water electrolysis may further include a support, which may be made of any material having a structure capable of supporting an iridium-based catalyst.

[0029] According to one embodiment, the carrier may include a ceramic support.

[0030] Examples of ceramic supports include antimony-doped tin oxides (ATO), alumina (Al2O3), titania (TiO2), zirconia (ZnO2), or combinations thereof. In one embodiment, the support is antimony-doped tin oxide.

[0031] The content of the iridium-based catalyst in the PEM water electrolysis electrode catalyst may be 10 to 90 parts by weight, 20 to 90 parts by weight, 20 to 85 parts by weight, 30 to 85 parts by weight, 30 to 80 parts by weight, or 30 to 70 parts by weight, relative to 100 parts by weight of the support. When the content of the iridium-based catalyst in the electrode catalyst is within the above range, the particle size of the iridium-based catalyst is uniform and the catalyst is uniformly present on the support without agglomeration, resulting in excellent dispersibility and improved durability. In addition, the OER activity of the electrode catalyst is improved, and its use allows the production of PEM water electrolysis electrodes and water electrolysis cells with improved durability.

[0032] The carrier may have a specific surface area of ​​5 to 1000 m 2 / g, 10-800m 2 / g, or 20 to 600 m 2 / g.

[0033] The electrode catalyst of the present invention has a core containing iridium metal formed inside the carrier to minimize the aggregation of iridium-based catalyst particles and improve the dispersion of the carrier, and the tin oxide (SnOx) formed on the core is alloyed to convert the iridium into iridium oxide (IrO x ) by increasing the crystallinity of the oxide when formed, resulting in core-shell particles with improved performance and durability.

[0034] According to one embodiment, the core of the PEM water electrolysis electrode catalyst may contain 60 to 76 parts by weight, 62 to 76 parts by weight, 63 to 75 parts by weight, or 65 to 75 parts by weight, relative to 100 parts by weight of the total PEM water electrolysis electrode catalyst, and the shell may contain 24 to 40 parts by weight, 25 to 38 parts by weight, 25 to 37 parts by weight, or 25 to 35 parts by weight, relative to 100 parts by weight of the total PEM water electrolysis electrode catalyst. If the iridium metal content is greater than the above range, the particle size of the iridium-based catalyst will decrease, but the content of iridium oxide in the shell will be relatively low, resulting in decreased OER activity. If the iridium tin oxide content in the shell is greater than the above range, the OER activity of the iridium oxide will increase, but the degree of particle dispersion will decrease, potentially reducing activity and durability.

[0035] The iridium tin composite oxide of the shell, which is the outermost layer of the electrode catalyst, is a composite containing iridium oxide and tin oxide, and the tin content in the iridium tin composite oxide is 33 to 50 mol, 34 to 48 mol, 35 to 45 mol, 37 to 45 mol, or 39 to 45 mol per 100 mol of iridium. If the tin content is less than the above range, the crystallinity of the iridium oxide may be low, resulting in a decrease in the OER activity of the electrode catalyst. If the tin content is more than the above range, the content of iridium oxide showing activity on the surface may be so low that the OER activity of the electrode catalyst may be low.

[0036] The iridium tin composite oxide shell according to one embodiment is a composite containing iridium oxide and tin oxide, and the content of tin oxide in the composite is 33 to 50 parts by weight, 34 to 48 parts by weight, 35 to 45 parts by weight, 37 to 45 parts by weight, or 39 to 45 parts by weight, per 100 parts by weight of iridium oxide. When the content of tin oxide is within the above range, the OER activity and durability of the PEM water electrolysis electrode catalyst are improved.

[0037] According to another embodiment, the iridium tin oxide present in the shell may further contain a metal dopant. Examples of such dopants include Sb, Nb, Ta, Bi, W, or In, or a combination thereof. The content of such metal dopants is 10 parts by weight or less, 5 parts by weight or less, or 0.01 to 5 parts by weight per 100 parts by weight of the iridium tin oxide. The inclusion of such metal dopants can improve the electrical conductivity of the electrode catalyst.

[0038] The PEM water electrolysis catalyst according to the present invention has a core-shell structure, and the iridium metal present inside can improve the dispersibility of catalyst particles on the support, thereby reducing particle size and physically increasing catalytic activity, and the iridium tin composite oxide catalyst present on the surface can significantly increase the crystallinity of iridium oxide, which has excellent chemical activity. Therefore, use of the electrode catalyst according to the present invention can simultaneously ensure catalytic activity and durability.

[0039] The average particle size of the core-shell iridium catalyst may be 1 nm to 20 nm. In this case, the average particle size of the core particles may be 0.5 nm to 10 nm, or 1 nm to 10 nm. When the average particle size of the iridium catalyst and the average particle size of the core particles are within the above ranges, an electrode catalyst with improved OER activity and durability can be produced.

[0040] FIG. 1 is a schematic diagram showing the structure of an electrode catalyst for PEM water electrolysis according to one embodiment.

[0041] The electrode catalyst 10 has a structure including a core 11 and cells 12 arranged on the core 11. The core 11 can contain iridium metal, and the shell 12 can contain an iridium-tin composite oxide. The electrode catalyst can have a structure as shown in FIG. 1, but is not limited to the average particle size of the core and the thickness of the shell shown in FIG. 1.

[0042] The electrode catalyst of the present invention can contain, for example, a compound represented by the following Chemical Formula 1.

[0043] <Chemical formula 1> Ir x Sn 1x O2 In Chemical Formula 1, 0.67≦x≦0.75.

[0044] In the compound of formula 1, iridium exists as a +4 valence and Sn also exists as a +4 valence.

[0045] The compound of Formula 1 can be, for example, Ir 0.67 Sn 0.33 O2, Ir 0.75 S 0.25 O2, or a combination thereof.

[0046] In the X-ray diffraction analysis spectrum of the electrode catalyst for PEM water electrolysis of the present invention, a multiplet peak (first peak) appears in the region where the diffraction angle 2θ is 26.6° to 28°, and a singlet peak (second peak) appears in the region where the diffraction angle 2θ is 40.5° to 40.9°, 40.6° to 40.8°, or 40.7°. In the present disclosure, the first peak is due to iridium tin composite oxide (IrSnO x ), and the second peak is the core iridium (Ir) peak.

[0047] According to another embodiment of the present invention, there is provided a method for producing an electrode catalyst for PEM water electrolysis containing an iridium-based catalyst.

[0048] The manufacturing method includes the steps of dispersing a carrier in a polyol to prepare a carrier dispersion, mixing an iridium precursor and a tin precursor with the polyol to obtain a precursor mixture, mixing the carrier dispersion with the precursor mixture to prepare a first mixture, performing a first heat treatment on the first mixture to prepare a catalyst precursor containing iridium metal and tin oxide particles, and washing and drying the catalyst precursor, followed by a second heat treatment in an oxidizing gas atmosphere.

[0049] The method for producing an electrode catalyst for PEM water electrolysis of the present invention will be described in more detail with reference to FIG.

[0050] First, a carrier dispersion is prepared by dispersing a carrier in a polyol.

[0051] The polyol content is 100 to 1,000 parts by weight or 200 to 400 parts by weight per part by weight of the carrier. When the polyol content is within the above range, the carrier is uniformly dispersed in the polyol, resulting in a carrier dispersion with excellent dispersibility. This dispersion process can be carried out using physical methods such as a homogenizer or ultrasonic device. If the ceramic content is high or the polyol content is low outside the above range, the ceramic support particles tend to form clumps and aggregate. If the ceramic support content is low or the polyol content is high, the reaction process efficiency is reduced, making it difficult to achieve the intended effects of the present invention.

[0052] The polyol may be at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, and glycerol. The polyol may be, for example, ethylene glycol, which is inexpensive, easily oxidized to glycolaldehyde at high temperatures, and has strong reducing power.

[0053] Separately, an iridium precursor and a tin precursor are mixed with a polyol to obtain a precursor mixture.

[0054] The molar ratio of the iridium precursor to the tin precursor is 1:0.33 to 1:0.50, or 1:0.35 to 1:0.48, or 1:0.37 to 1:0.45. When the molar ratio of the iridium precursor to the tin precursor is within the above range, an electrocatalyst having a core / shell structure and improved activity can be produced. If the molar ratio of the iridium precursor to the tin precursor is outside the above range, an Ir-SnO2 composite or IrSnO2 composite is formed, making it impossible to produce a catalyst having the desired core / shell structure.

[0055] The content of polyol used in producing the precursor mixture is, for example, 10 to 1000 parts by weight or 200 to 400 parts by weight per part by weight of the total weight of the iridium precursor and the tin precursor. In the step of obtaining the precursor mixture, a precursor mixture having a uniform composition can be obtained using a physical method such as a homogenizer or an ultrasonic device.

[0056] Examples of iridium precursors include iridium nitrate, iridium sulfate, iridium chloride, and hexachloroiridic acid (ClH 14 IrO6; H2IrCl6·6H2O) or the like can be used, and the tin precursor can be, for example, tin chloride, tin sulfate, or tin chloride.

[0057] The support dispersion obtained according to the above process is mixed with a precursor mixture to prepare a first mixture, where the support dispersion and the precursor mixture can be stoichiometrically adjusted to obtain the desired composition of the electrode catalyst.

[0058] Next, the first mixture obtained according to the above process is subjected to a first heat treatment to produce a catalyst precursor A containing iridium metal and tin oxide particles.

[0059] The first heat treatment is carried out at 200° C. to 550° C., 230° C. to 500° C., or 250° C. to 400° C. If the first heat treatment is carried out at a temperature lower than 200° C. or higher than 550° C., it becomes difficult to form the intended catalyst precursor A.

[0060] After the catalyst precursor A is washed and dried, it is subjected to a second heat treatment to obtain the electrode catalyst of the present invention.

[0061] The second heat treatment is carried out at a temperature higher than that of the first heat treatment.

[0062] The second heat treatment is carried out in an oxidizing gas atmosphere at a temperature of 350°C to 600°C, 350°C to 550°C, or 350°C to 450°C. If the temperature during the second heat treatment is less than 350°C, an Ir-SnO2 composite may exist, potentially resulting in reduced activity. If the temperature during the second heat treatment is more than 600°C, an electrode catalyst formed of an IrSnO2 composite may be formed, rather than the core-shell electrode catalyst structure of the present invention. If this electrode catalyst is used, the performance of the PEM water electrolysis electrode may be reduced.

[0063] The oxidizing gas atmosphere may be, for example, an oxygen atmosphere or an air atmosphere. If the second heat treatment is performed in an inert gas atmosphere instead of an oxidizing gas atmosphere, an electrocatalyst composed of an IrSnO2 composite may be formed instead of the core-shell electrocatalyst structure of the present invention, which may result in a decrease in the performance of the electrocatalyst.

[0064] The polyol used in the method for preparing the electrode catalyst for PEM water electrolysis can act as a solvent and a reducing agent to reduce the metal precursor.

[0065] According to another embodiment, there is provided a PEM water electrolysis electrode comprising an anode comprising the electrocatalyst of the present invention, wherein the water electrolysis electrode can be, for example, the anode.

[0066] According to another embodiment, there is provided a water electrolysis cell comprising a PEM water electrolysis electrode comprising the electrode catalyst of the present invention and a polymer electrolyte membrane.

[0067] The water electrolysis cell may contain a membrane electrode assembly.

[0068] The PEM water electrolysis cell according to the present invention includes one or more membrane electrode assemblies, and the membrane electrode assemblies may have a structure as shown in FIG.

[0069] Referring to FIG. 7, the membrane electrode assembly for PEM water electrolysis has a structure in which a cathode 100 is disposed on one side of a polymer electrolyte membrane 300 and an anode 200 is disposed on the other side of the polymer electrolyte membrane 300.

[0070] Anode 200 can include an electrocatalyst of the present invention as an electrocatalyst, which is a material that promotes OER.

[0071] The cathode 100 includes a cathode catalyst, which is a material that promotes the hydrogen evolution reaction (HER) in a PEM water electrolysis cell, and can be one or a mixture of two or more selected from the group consisting of platinum, ruthenium, iridium, osmium, palladium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and oxides thereof. The cathode catalyst can be, for example, platinum-coated carbon powder (Pt / C).

[0072] The cathode 100 and the anode 200 may each contain an ionomer. The ionomer is a polymer having proton conductivity, and examples thereof include polytetrafluoroethylene, a polymer represented by the following Chemical Formula 2, a polymer represented by the following Chemical Formula 3, a polymer represented by the following Chemical Formula 4, or a combination thereof.

[0073] <Chemical formula 2>

[0074] [ka]

[0075] In Chemical Formula 2, m is a natural number, <Chemical formula 3>

[0076] [ka]

[0077] In Chemical Formula 3, p is a natural number, <Chemical formula 4>

[0078] [ka]

[0079] In Chemical Formula 4, n is a natural number.

[0080] The polymer represented by Chemical Formula 2 is a polymer consisting of a polytetrafluoroethylene skeleton as the main chain and perfluoroether pendant side chains having sulfonic acid groups at their terminals. The equivalent weight (EW) of the polymer (the mass of the polymer required to supply 1 mole of protons) is not limited, but is, for example, 900 to 1200 g / mol. In Chemical Formula 2, m has a range that can be calculated from the equivalent weight.

[0081] The ion-conductive polymer of Chemical Formula 2 may be, for example, Nafion (EW: 1100 g / mol, the average value of m in Chemical Formula 2 is 6.6).

[0082] The polymers represented by Chemical Formula 2 or 3 are polymers consisting of a polytetrafluoroethylene backbone in the main chain and perfluoroether pendant side chains having sulfonic acid groups at their terminals. The equivalent weight (EW) of the polymers (the mass of the polymer required to supply 1 mole of protons) is not limited, but is, for example, 700 to 9500 g / mol. In Chemical Formulas 3 and 4, p and n each have a range that can be calculated from the equivalent weight.

[0083] The ion-conducting polymer of the above formula 3 or 4 may be, for example, 3M Ionomer manufactured by 3M Corporation.

[0084] The polymer electrolyte membrane 300 refers to a membrane formed of a polymer having a cation exchange group capable of transmitting hydrogen ions, and is a material located between the anode and the cathode in the PEM water electrolysis cell, serving as a path through which hydrogen ions move, and may include a fluorine-based polymer or a hydrocarbon-based polymer. For example, the hydrocarbon-based polymer may include sulfonated polysulfone, sulfonated polyethersulfone, sulfonated polyether ketone, sulfonated polyether ether ketone, sulfonated polyether ketone, sulfonated polyarylene ether ketone, sulfonated polyarylene ether sulfone, sulfonated polyarylether benzimidazole, and mixtures thereof. The fluorine-based polymer may include polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (fluorinated ethylene propylene), and mixtures thereof. ethylene-propylene, FEP), or mixtures thereof.

[0085] The polymer electrolyte membrane may be made of Nafion (Dupont, USA), a typical fluorine-based polymer.

[0086] The method for producing the membrane electrode assembly for PEM water electrolysis of the present invention will now be considered.

[0087] First, an anode catalyst, the electrode catalyst for PEM water electrolysis of the present invention, an ionic polymer, and a solvent are mixed to prepare a composition for forming an anode, which is then coated on a substrate and dried to prepare an anode.

[0088] Separately, a cathode-forming composition is prepared using a cathode catalyst, an ionic polymer, and a solvent, and the composition is coated on a substrate and dried to produce a cathode.

[0089] The coating method of the cathode-forming composition and the anode-forming composition when manufacturing the cathode and the anode, respectively, can be one selected from the group consisting of spray coating, screen printing, tape casting, brushing, printing, and slot die casting.

[0090] A cathode is laminated on one side of the polymer electrolyte membrane, and an anode is laminated on the other side of the polymer electrolyte membrane to manufacture a membrane electrode assembly. One or more membrane electrode assemblies can be stacked to manufacture a PEM water electrolysis cell.

[0091] The present invention will be described in detail below with reference to examples. However, the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0092] (Production of electrode catalysts) Example 1 0.75 g of antimony (Sb)-doped tin oxide (ATO, 47.2 m 2 A carrier dispersion was prepared by ultrasonically mixing 350 g of ethylene glycol (EG) with 350 g of PEG (1 / g, Sigma-Aldrich) at high speed for 30 minutes.

[0093] The catalyst particle precursor solution was prepared by mixing 20.60 g of an aqueous iridium precursor solution (5 wt%, H2IrCl6·xH2O, TMI Chem. Co.) with 1.88 g of a tin precursor solution (20 wt%, SnCl2·2H2O in EG, Sigma-Aldrich). The molar ratio of the iridium precursor to the tin precursor was 1:0.33.

[0094] The carrier dispersion and the catalyst particle precursor solution were mixed, and the mixture was placed in an autoclave reactor equipped with a stirrer. The temperature of the reactor was raised to about 250° C. to carry out a first heat treatment, thereby carrying out a reduction reaction. After the reduction reaction was completed, a filtration / washing process was repeated to obtain a slurry, which was then freeze-dried to produce a catalyst precursor.

[0095] The catalyst precursor was subjected to a second heat treatment at 450°C in an air atmosphere furnace for 6 hours to obtain an electrode catalyst (Ir@IrSnO2-1).

[0096] The composition of the electrode catalyst, when expressed as a combination of the core and shell, is Ir 0.75 Sn 0.25 It is O2.

[0097] Example 2 An electrode catalyst (Ir@IrSnO2-2) was prepared in the same manner as in Example 1, except that 18.98 g of an iridium precursor aqueous solution (5 wt%, H2IrCl6·xH2O, TMI Chem. Co.) and 2.60 g of a tin precursor solution (20 wt%, SnCl2·2H2O in EG, Sigma-Aldrich) were prepared. The molar ratio of the iridium precursor to the tin precursor was 1:0.5. The composition of the electrode catalyst, including the core and shell, was Ir 0.67 Sn 0.33 It is O2.

[0098] Example 3 An electrode catalyst (Ir@IrSnO2-3) was obtained in the same manner as in Example 1, except that the mixing molar ratio of the iridium precursor and the tin precursor was changed to 1:0.4.

[0099] Example 4 An electrode catalyst (Ir@IrSnO2-4) was obtained in the same manner as in Example 1, except that the mixing molar ratio of the tin precursor to the tin precursor was changed to 1:0.45.

[0100] Comparative Example 1 An electrode catalyst (IrO2) was produced in the same manner as in Example 1, except that 24.85 g of an iridium precursor aqueous solution (5 wt%, H2IrCl6·xH2O, TMI Chem. Co.) was used without adding a tin precursor solution. The molar ratio of the iridium precursor to the tin precursor was 1:0.

[0101] Comparative Example 2 15.36 g of iridium precursor aqueous solution (5 wt%, H2IrCl6·xH2O, TMI Chem. Co.) and 4.21 g of tin precursor solution (20 wt%, SnCl2·2H2O An electrode catalyst (IrSnO2) was produced in the same manner as in Example 1, except that an iridium precursor and a tin precursor (in EG, Sigma-Aldrich) were mixed. The mixing molar ratio of the iridium precursor to the tin precursor was 1:1.

[0102] Comparative Example 3 An electrode catalyst (Ir-SnO2 composite) was obtained in the same manner as in Example 1, except that the second heat treatment of the catalyst precursor was carried out in a nitrogen gas atmosphere.

[0103] The electrode catalyst prepared according to Comparative Example 3 yields an Ir-SnO2 composite, which does not have a core-shell structure but is in the form of a compound having a single composition.

[0104] The molar ratio of the iridium precursor and the tin precursor used in the preparation of the electrode catalysts prepared in Examples 1 and 2 and Comparative Examples 1 and 2, and the composition of the final electrode catalysts are shown in Table 1 below.

[0105] [Table 1]

[0106] (Production of PEM water electrolysis cells) Example 1 A slurry was prepared by mixing 0.5 g of the electrode catalyst (Ir@IrSnO2-1) of Example 1, 2.2 g of water, 2.2 g of dipropylene glycol, and 0.27 g of 20% Nafion dispersion. The slurry was then coated on a PTFE (polytetrafluoroethylene) film and dried to prepare an anode as an electrode layer.

[0107] Similarly to the anode electrode layer, the cathode was prepared by preparing a slurry using 20 wt.% Pt / C, and then coating and drying the slurry on a PTFE (polytetrafluoroethylene) film to prepare an electrode layer.

[0108] A cation exchange membrane (Nafion 115) was laminated on top of the cathode, and the catalytic surface of the anode electrode (OER electrode) was placed on top of the cation exchange membrane. The anode electrode was then heat-sealed at 165°C and 20 bar for 10 minutes to produce a membrane electrode assembly (MEA). The MEA was placed in a unit cell with a flow path, and a titanium porous transport layer (Ti-PTL) was laminated on the anode side to produce a membrane electrode assembly. The assembly was then fastened together to produce a PEM water electrolysis unit cell.

[0109] Examples 2-4 A membrane electrode assembly and a PEM water electrolysis unit cell were produced in the same manner as in Production Example 1, except that the electrode catalysts of Examples 2 to 4 were used instead of the electrode catalyst of Example 1, respectively.

[0110] Comparative production example 1 A membrane electrode assembly and a PEM water electrolysis unit cell were produced in the same manner as in Production Example 1, except that the electrode catalyst of Comparative Example 1 was used instead of the electrode catalyst of Example 1.

[0111] Comparative production example 2 A membrane electrode assembly and a PEM water electrolysis unit cell were produced in the same manner as in Production Example 1, except that the electrode catalyst of Comparative Example 2 was used instead of the electrode catalyst of Example 1.

[0112] Evaluation example 1: X-ray diffraction analysis (XRD) To confirm the crystallographic information of the PEM water electrolysis electrode catalysts of Examples 1 and 2 and Comparative Examples 1 and 2, analysis was performed using an X-ray diffraction method (XRD, Rigaku DMAX-33) using CuKα radiation with a diffraction angle 2θ in the range of 10° to 80°. The analysis results are shown in Figure 3.

[0113] According to FIG. 3, the catalysts of Examples 1 and 2 simultaneously exhibit the Ir metal peak, the IrSnO2 peak, and the ATO support peak, indicating that IrSnO2 in particular has excellent crystallinity.

[0114] In the X-ray diffraction analysis spectrum of the electrode catalyst, a multiplet peak appears in the region of diffraction angle 2θ between 26.6° and 28°, and a singlet peak appears in the region of diffraction angle 2θ between 40.5° and 40.9°. The multiplet peak is IrSnO x The singlet peak is the iridium-related peak of the electrocatalyst core.

[0115] In contrast, the catalyst (IrO2) of Comparative Example 1 was tin-free, the iridium oxide (IrOx) was not crystalline, and no Ir metal peak was observed.The catalyst (IrSnO2) of Comparative Example 2 was found to have a high Sn content and an IrSnO2 (crystalline) composite structure with no Ir metal in the catalyst core.

[0116] Evaluation example 2: Transmission electron microscope (TEM) analysis TEM analysis was performed on the electrode catalysts according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2. The TEM analysis results are shown in Figures 4a, 4b, 4c, 4d, 5a, 5b, 5c, and 5d. Here, Figures 4a, 4c, 5a, and 5c are TEM photographs of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, respectively, before the second heat treatment, and Figures 4b, 4d, 5b, and 5d are TEM photographs of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, respectively, after the second heat treatment.

[0117] With reference to this, the electrocatalysts according to Examples 1 and 2 exhibited improved dispersion compared to the electrocatalysts of Comparative Examples 1 and 2.

[0118] Evaluation example 3: Water electrolysis performance evaluation PEM water electrolysis electrodes were fabricated using the electrode catalysts of Examples 1 and 2, Comparative Examples 1 and 2, and these electrodes were used to fabricate PEM water electrolysis membrane electrode assemblies and PEM water electrolysis cells including the same of Fabrication Examples 1 and 2 and Comparative Fabrication Examples 1 and 2. The cell voltage as a function of current density, which indicates the electrochemical effect of such PEM water electrolysis cells, was measured to evaluate the water electrolysis performance.

[0119] The voltage V and current A measured in the evaluation are shown in Table 2 below and in FIG.

[0120] [Table 2]

[0121] Referring to Table 1 and FIG. 6 , it can be seen that the water electrolysis cells having PEM water electrolysis electrodes using the catalysts of Examples 1 and 2 at 1.7 V have improved current densities compared to the water electrolysis cells having electrodes using the electrode catalysts of Comparative Examples 1 and 2 at the same voltage.

[0122] Furthermore, PEM water electrolysis electrodes were produced using the electrode catalysts of Examples 3 and 4, and these electrodes were used to produce PEM water electrolysis membrane electrode assemblies and PEM water electrolysis cells containing the same of Production Examples 3 and 4. The water electrolysis performance of these PEM water electrolysis cells was evaluated in the same manner as for the water electrolysis cell of Production Example 1.

[0123] As a result of the evaluation, it was confirmed that the water electrolysis cells of Production Examples 3 and 4 achieved water electrolysis performance equivalent to that of the water electrolysis cell of Production Example 1.

[0124] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0125] [Explanation of symbols] 100 cathode 200 anodes 300 Polymer electrolyte membrane [Brief explanation of the drawings]

[0126] [Figure 1] FIG. 1 is a diagram schematically illustrating the core-shell structure of a polymer electrolyte membrane (PEM) water electrolysis electrode catalyst according to the present invention. [Figure 2] 1 is a flowchart illustrating a method for producing an electrode catalyst for PEM water electrolysis according to the present invention. [Figure 3] FIG. 1 is a diagram showing X-ray diffraction analysis spectra of catalysts according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2. [Figure 4a] and [Figure 4b] 1A and 1B are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Example 1, respectively. [Figure 4c] and [Figure 4d]1A and 1B are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Example 2, respectively. [Figure 5a] and [Figure 5b] 1A and 1B are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing the electrode catalyst of Comparative Example 1, respectively. [Figure 5c] and [Figure 5d] 1A and 1B are transmission electron microscope photographs showing the state before and after the second heat treatment in the process of producing an electrode catalyst of Comparative Example 2, respectively. [Figure 6] 1 is a graph showing voltage changes with current density in PEM water electrolysis cells equipped with electrodes containing the electrode catalysts according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2. [Figure 7] FIG. 1 is a diagram schematically illustrating the structure of a water electrolysis cell having a membrane electrode assembly for PEM water electrolysis of the present invention.

Claims

1. The polymer electrolyte membrane (PEM) water electrolysis electrode catalyst contains an iridium-based catalyst. The iridium-based catalyst is a core-shell particle, the core comprises iridium metal; The shell comprises an iridium tin composite oxide.

2. the content of iridium metal in the core is 60 to 76 parts by weight relative to 100 parts by weight of the total electrode catalyst; 2. The electrode catalyst for PEM water electrolysis according to claim 1, wherein the content of the iridium tin composite oxide in the shell is 24 to 40 parts by weight per 100 parts by weight of the total electrode catalyst.

3. the iridium tin composite oxide of the cell is a composite containing iridium oxide and tin oxide; 2. The electrode catalyst for PEM water electrolysis according to claim 1, wherein the content of tin oxide in the composite is 33 to 50 parts by weight per 100 parts by weight of iridium oxide.

4. 2. The electrode catalyst for PEM water electrolysis according to claim 1, wherein the iridium tin composite oxide of the cell has a tin content of 33 to 50 mol per 100 mol of iridium.

5. The electrocatalyst further comprises a support; The electrode catalyst for PEM water electrolysis according to claim 1 , wherein the iridium-based catalyst is supported on a carrier.

6. 6. The electrode catalyst for PEM water electrolysis according to claim 5, wherein the content of the iridium-based catalyst is 10 to 90 parts by weight per 100 parts by weight of the support.

7. The PEM water electrolysis electrocatalyst according to claim 5 , wherein the support comprises a ceramic support.

8. The ceramic support is made of antimony-doped tin oxide (ATO), alumina (Al ２ O ３ ), titanium (TiO ２ ), zirconia (ZnO ２ 8. The PEM water electrolysis electrode catalyst according to claim 7, wherein the catalyst is selected from the group consisting of:

9. In the X-ray diffraction analysis spectrum of the electrode catalyst, a multiplet peak appears in the region of a diffraction angle 2θ of 26.6° to 28°, 2. The PEM water electrolysis electrode catalyst according to claim 1, wherein a singlet peak appears in the region of a diffraction angle 2θ of 40.5° to 40.9°.

10. The electrode catalyst for PEM water electrolysis according to claim 1 , comprising a compound represented by the following Chemical Formula 1: <Chemical formula 1> I ｘ Sn １ｘ O ２ (Wherein, 0.67≦x≦0.75.)

11. The electrode catalyst is Ir ０．６７ Sn ０．３３ O ２ , Ir ０．７５ S ０．２５ O ２ 11. The PEM water electrolysis electrocatalyst according to claim 10, wherein the catalyst is a fluorine-containing compound, ...

12. 2. The PEM water electrolysis electrode catalyst according to claim 1, wherein the average diameter of the electrode catalyst is 1 nm to 20 nm.

13. Dispersing a carrier in a polyol to produce a carrier dispersion; mixing an iridium precursor and a tin precursor with a polyol to obtain a precursor mixture; mixing the carrier dispersion and a precursor mixture to form a first mixture; performing a first heat treatment of the first mixture to produce a catalyst precursor comprising iridium metal and tin oxide particles; and washing and drying the catalyst precursor, and then performing a second heat treatment under an oxidizing gas atmosphere, thereby producing the polymer electrolyte membrane (PEM) water electrolysis electrode catalyst according to claim 1; The method for producing an electrode catalyst for PEM water electrolysis, wherein the mixing molar ratio of the iridium precursor to the tin precursor is 1:0.33 to 0.

50.

14. The method for producing an electrode catalyst for PEM water electrolysis according to claim 13, wherein the first heat treatment is performed at 200 to 550°C.

15. The second heat treatment is performed at a temperature higher than that of the first heat treatment, The second heat treatment is carried out at a temperature of 350 to 600°C, The method for producing an electrode catalyst for PEM water electrolysis according to claim 13, wherein the oxidizing gas atmosphere includes an air atmosphere or an oxygen gas atmosphere.

16. The method for producing an electrode catalyst for PEM water electrolysis according to claim 13, wherein the total content of the iridium precursor and the tin precursor is 10 to 90 parts by weight per 100 parts by weight of the support.

17. A polymer electrolyte membrane (PEM) water electrolysis electrode comprising the PEM water electrolysis electrode catalyst according to any one of claims 1 to 12.

18. a polymer electrolyte membrane; A PEM water electrolysis cell comprising a PEM water electrolysis electrode, the PEM water electrolysis electrode comprising: a PEM water electrolysis electrode catalyst according to any one of claims 1 to 12, the PEM water electrolysis electrode being located on one side of the polymer electrolyte membrane.

19. 20. The PEM water electrolysis cell of claim 18, wherein the electrode is an anode.

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