Anion exchange membrane-type water electrolysis anode catalyst, anion exchange membrane-type water electrolysis anode catalyst layer, anion exchange membrane-type water electrolytic cell, and water electrolytic cell stack

Abstract

To provide an anion exchange membrane-type water electrolysis anode catalyst with excellent alkali resistance, an anion exchange membrane-type water electrolysis anode catalyst layer, an anion exchange membrane-type water electrolytic cell, and a water electrolytic cell stack.SOLUTION: Provided are an anion exchange membrane-type water electrolysis anode catalyst and the application thereof, which has a perovskite-type structure including at least one kind of ions selected from a group consisting of calcium ions, strontium ions, and barium ions as A-site ion, and tetravalent metal ions and iridium ions as B-site ion. The ratio of the molar concentration of the iridium ions to the total molar concentration of all the metal ions included in the B-site ion is 0.30 or more and 0.57 or less. In an alkaline solution, an oxygen evolution reaction occurs according to the following expression: 4OH- → 2H2O + O2 + 4e- (I).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an anion exchange membrane water electrolysis anode catalyst, an anion exchange membrane water electrolysis anode catalyst layer, an anion exchange membrane water electrolysis cell, and a water electrolysis cell stack. [Background technology]

[0002] Water electrolysis (hereinafter sometimes referred to as "water electrolysis") is a method for producing hydrogen and oxygen from water by electrolysis. For example, among technologies that use hydrogen as an energy source, water electrolysis is a promising technology for sustainable hydrogen production.

[0003] A cell used for water electrolysis (a so-called water electrolysis cell) includes, for example, an anode separator, an anode gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode separator. The anode catalyst used for water electrolysis is required to have properties suitable for water electrolysis, and various studies have been conducted on it.

[0004] For example, Patent Document 1 discloses an oxide having a perovskite structure, which contains divalent or trivalent metal ions as A-site ions and tetravalent or trivalent metal ions (excluding iridium ions) and iridium ions as B-site ions, and when the A-site ions contain strontium ions, the B-site ions contain at least tin ions, or the A-site ions contain calcium ions, or the B-site ions contain zirconium ions, and the ionic radius (Å) of the B-site ions is r B The ionic radius (Å) of the tetravalent or trivalent metal ion i contained in the B site ion is defined as r i , the molar concentration of tetravalent or trivalent metal ion i contained in the B site ions is m i , the ionic radius of the iridium ion (Å) is r Ir , the molar concentration of iridium ions is m Ir When the ionic radius difference between the B-site ion and the iridium ion defined by a certain formula (rB -r Ir ) is −0.0120 to 0.0700. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7307845 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the development of water electrolysis technology using anion exchange membranes (AEM) has been progressing. The electrode reaction of anion exchange membrane water electrolysis cells is the same as alkaline water electrolysis, with hydroxide ions (OH - ) as a carrier and uses an alkaline aqueous solution. Therefore, the anode catalyst is exposed to an alkaline atmosphere during water electrolysis, which may shorten the catalyst's lifespan, and there is a need to develop an anode catalyst with excellent alkali resistance.

[0007] An object of one embodiment of the present disclosure is to provide an anode catalyst for anion exchange membrane water electrolysis that has excellent alkali resistance. Another problem to be solved by another embodiment of the present disclosure is to provide an anode catalyst layer for anion exchange membrane water electrolysis, an anion exchange membrane water electrolysis cell, and a water electrolysis cell stack, each including the anion exchange membrane water electrolysis anode catalyst. [Means for solving the problem]

[0008] Specific means for solving the problems include the following aspects. <1> A perovskite structure in which the A-site ions include at least one selected from the group consisting of calcium ions, strontium ions, and barium ions, and the B-site ions include tetravalent metal ions and iridium ions, the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions [molar concentration of iridium ions / total molar concentration of all metal ions contained in the B site ions] is in the range of 0.30 or more and 0.57 or less; An anode catalyst for anion exchange membrane water electrolysis, in which an oxygen evolution reaction according to the following formula (I) occurs in an alkaline solution: 4OH - → 2H2O + O2+ 4e - (I) <2> The tetravalent metal ion includes at least one selected from the group consisting of a titanium ion, a zirconium ion, and a tin ion. <1> The anion exchange membrane water electrolysis anode catalyst according to claim 1. <3> the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions [molar concentration of iridium ions / total molar concentration of all metal ions contained in the B site ions] is in the range of 0.31 or more and 0.55 or less; <1> or <2> The anion exchange membrane water electrolysis anode catalyst according to claim 1. <4> the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions [molar concentration of iridium ions / total molar concentration of all metal ions contained in the B site ions] is in the range of 0.34 to 0.53; <1> or <2> The anion exchange membrane water electrolysis anode catalyst according to claim 1. <5> <1> ~ <4> and an ionomer, An anode catalyst layer for anion exchange membrane water electrolysis, wherein the ratio of the amount of ionomer per unit area to the amount of iridium per unit area [amount of ionomer per unit area / amount of iridium per unit area] is greater than 0 and not greater than 0.32. <6> The ratio of the amount of ionomer per unit area to the amount of iridium per unit area [amount of ionomer per unit area / amount of iridium per unit area] is in the range of more than 0 and not more than 0.29. <5> The anion exchange membrane water electrolysis anode catalyst layer according to claim 1. <7> the ratio of the amount of ionomer per unit area to the amount of iridium per unit area [amount of ionomer per unit area / amount of iridium per unit area] is in the range of more than 0 and not more than 0.25; <5> The anion exchange membrane water electrolysis anode catalyst layer according to claim 1. <8> an anode separator; an anode gas diffusion layer; <5> ~ <7> an anion exchange membrane water electrolysis cell comprising the anode catalyst layer for anion exchange membrane water electrolysis according to any one of the above items, an electrolyte membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode separator. <9> <8> A water electrolysis cell stack in which a plurality of the anion exchange membrane water electrolysis cells according to claim 1 are stacked. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, there is provided an anion exchange membrane water electrolysis anode catalyst having excellent alkali resistance. According to other embodiments of the present disclosure, there are provided an anion exchange membrane water electrolysis anode catalyst layer, an anion exchange membrane water electrolysis cell, and a water electrolysis cell stack, each including the anion exchange membrane water electrolysis anode catalyst. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a water electrolysis cell according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a graph showing the relationship between the log{current density (mA / cm)} of the anode catalyst layer and the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in B-site ions in the anode catalyst [molar concentration of iridium ions / total molar concentration of all metal ions contained in B-site ions] in Examples and Comparative Examples in which a current test was conducted in an alkaline environment. [Figure 3]FIG. 3 is a graph showing the relationship between log{current density (mA / cm)} of the anode catalyst layer and the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer [amount of ionomer per unit area / amount of iridium per unit area] in Examples and Comparative Examples in which a current test was conducted in an alkaline environment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure is not limited to the following embodiments, and can be implemented by making appropriate modifications within the scope of the object of the present disclosure. The dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios.

[0012] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0013] In the numerical ranges described in stages in the present disclosure, the upper limit value described in one numerical range may be replaced with the upper limit value of another numerical range described in stages, and the lower limit value described in one numerical range may be replaced with the lower limit value of another numerical range described in stages. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with a value shown in the examples.

[0014] In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0015] [Anode catalyst for anion exchange membrane water electrolysis] The anion exchange membrane water electrolysis anode catalyst (hereinafter also simply referred to as "anode catalyst") of the present disclosure has a perovskite structure in which the A-site ions include at least one ion selected from the group consisting of calcium ions, strontium ions, and barium ions, and the B-site ions include a tetravalent metal ion and an iridium ion, and the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions included in the B-site ions [molar concentration of iridium ions / total molar concentration of all metal ions included in the B-site ions] is in the range of 0.30 or more and 0.57 or less, and an oxygen evolution reaction occurs in an alkaline solution according to the following formula (I): 4OH - → 2H2O + O2+ 4e - (I)

[0016] The anode catalyst of the present disclosure has the property of being excellent in alkali resistance. The anode catalyst of the present disclosure has a perovskite structure, and tends to have excellent alkali resistance because the molar concentration of iridium ions among the B-site ions of the perovskite structure is within a specific range.

[0017] The anode catalyst of the present disclosure has a perovskite structure. Compounds with a perovskite structure are generally represented by the chemical formula ABO3. Some compounds with a perovskite structure have oxygen instability. The amount of oxygen in a compound with a perovskite structure may be deficient or excessive relative to 3. The A-site ions and B-site ions may be partially substituted with different elements.

[0018] The A-site ions of the perovskite structure include at least one selected from the group consisting of calcium ions, strontium ions, and barium ions. The A-site ions of the perovskite structure may include only one or more of calcium ions, strontium ions, and barium ions.

[0019] The A-site ions in the perovskite structure may contain metal ions other than calcium ions, strontium ions, and barium ions (hereinafter also referred to as "other metal ions A"). Examples of the other metal ions A include trivalent metal ions such as aluminum (Al), chromium (Cr), and iron (Fe), as well as alkaline earth metal ions other than calcium ions, strontium ions, and barium ions, such as beryllium (Be) ions and magnesium (Mg) ions. From the viewpoint of better achieving the effects of the present disclosure, it is preferable that the A site ions in the perovskite structure do not contain other metal ions A, that is, the A site ions are at least one type selected from the group consisting of calcium ions, strontium ions, and barium ions.

[0020] The B-site ions in the perovskite structure include tetravalent metal ions and iridium (Ir) ions. The type of tetravalent metal ion is not particularly limited. The tetravalent metal ions preferably include at least one selected from the group consisting of titanium (Ti) ions, zirconium (Zr) ions, and tin (Sn) ions. The B-site ions of the perovskite structure preferably include at least one selected from the group consisting of titanium ions, zirconium ions, and tin ions, and iridium ions.

[0021] The B-site ions in the perovskite structure may or may not contain metal ions other than tetravalent metal ions and iridium ions (hereinafter also referred to as "other metal ions B"). When the B site ions of the perovskite structure include other metal ions B, the other metal ions B are not particularly limited as long as they are metal ions that can be located at the B site. Examples of other metal ions B include vanadium (V) ions, niobium (Nb) ions, tantalum (Ta) ions, chromium (Cr) ions, molybdenum (Mo) ions, tungsten (W) ions, manganese (Mn) ions, iron (Fe) ions, ruthenium (Ru) ions, cobalt (Co) ions, nickel (Ni) ions, and gallium (Ga) ions.

[0022] From the viewpoint of alkali resistance, the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B-site ions of the perovskite structure [molar concentration of iridium ions / total molar concentration of all metal ions contained in the B-site ions] is in the range of 0.30 or more and 0.57 or less, preferably in the range of 0.31 or more and 0.55 or less, and more preferably in the range of 0.34 or more and 0.53 or less.

[0023] The type and concentration of metal ions contained in the perovskite structure can be identified by analytical methods such as high-frequency inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy, electron beam microanalysis, and X-ray photoelectron spectroscopy.

[0024] The form of the anode catalyst is not particularly limited, but is preferably, for example, in the form of particles.

[0025] The method for producing the anode catalyst of the present disclosure is not particularly limited. The anode catalyst of the present disclosure can be produced by a conventionally known method, for example, a conventionally known solid-phase method or liquid-phase method. An example of a solid phase method is a method that involves a direct reaction of solid raw materials. Examples of the liquid phase method include the Pezzini method, the complex polymerization method, and the hydrothermal synthesis method.

[0026] [Anode catalyst layer for anion exchange membrane water electrolysis] The anode catalyst layer for anion exchange membrane water electrolysis according to the present disclosure (hereinafter also simply referred to as "anode catalyst layer") comprises the anode catalyst according to the present disclosure and an ionomer, and the ratio of the amount of ionomer per unit area to the amount of iridium per unit area is in the range of more than 0 and not more than 0.32. The anode catalyst layer of the present disclosure has excellent alkali resistance.

[0027] The anode catalyst layer of the present disclosure comprises the anode catalyst of the present disclosure. The anode catalyst of the present disclosure has been described above, and therefore, a description thereof will be omitted here.

[0028] The anode catalyst layer of the present disclosure comprises an ionomer. The ionomer is not particularly limited. As the ionomer, for example, Nafion (registered trademark) is preferred, which has excellent stability against alkalis and can improve the adhesion between catalyst particles in the anode catalyst layer and between the anode catalyst layer and the electrolyte membrane.

[0029] The ionomer may be, for example, an ionomer having anion conductivity. By using an ionomer having anion conductivity as the ionomer, the number of reaction sites formed at the contact interface with the anode catalyst can be increased, and a migration path for hydroxide ions can be formed within the anode catalyst layer, thereby reducing the resistance of the cell. Examples of ionomers having anion conductivity include polyethylene-based ionomers, benzimidazolium-based ionomers, polystyrene-based ionomers, aryl-based ionomers, polynorbornene-based ionomers, ethersulfone-based ionomers, and fluorine-based ionomers.

[0030] The chemical structure of an ionomer can be confirmed by a combination of solid-state NMR (nuclear magnetic resonance) measurement and CHN analysis (atomic analysis of carbon C, hydrogen H, and nitrogen N). The ratio of the anode catalyst to the ionomer can be confirmed by ICP (inductively coupled plasma) analysis.

[0031] The amount of iridium per unit area of ​​the anode catalyst layer of the present disclosure is 0 mg-Ir / cm from the viewpoint of alkali resistance. 2 Exceeds 0.200 mg-Ir / cm 2 The range is preferably 0.020 mg-Ir / cm 2 More than 0.150mg-Ir / cm 2 More preferably, the range is 0.062 mg-Ir / cm 2 More than 0.118mg-Ir / cm 2 The following range is more preferred: Here, "mg-Ir / cm 2 " is a unit that indicates the amount of iridium per unit area.

[0032] In the present disclosure, the amount of iridium per unit area of ​​the anode catalyst layer is measured by the following method. A 2 cm square piece of the anode catalyst layer is cut and dissolved in aqua regia to prepare analytical sample solution A. Analytical sample solution A is subjected to ICP (inductively coupled plasma) analysis using an ICP emission spectrometer to determine the amount of iridium per unit area of ​​the anode catalyst layer. As an ICP optical emission spectrometer, for example, a high-resolution ICP optical emission spectrometer PS3520VDDII (model) manufactured by Hitachi High-Tech Science Corp. can be suitably used. However, the ICP optical emission spectrometer is not limited to this.

[0033] The amount of iridium per unit area of ​​the anode catalyst layer can be controlled by the amount of iridium contained in the catalyst component, the amount of catalyst blended in the coating liquid (so-called anode slurry) for forming the anode catalyst layer, the amount of anode slurry applied, etc.

[0034] From the viewpoint of alkali resistance, the anode catalyst layer of the present disclosure has a ratio of the amount of ionomer per unit area to the amount of iridium per unit area [amount of ionomer per unit area / amount of iridium per unit area] in the range of more than 0 and not more than 0.32, preferably in the range of more than 0 and not more than 0.29, and more preferably in the range of more than 0 and not more than 0.25.

[0035] In the present disclosure, the amount of ionomer per unit area of ​​the anode catalyst layer (unit: mg / cm 2 ) is measured in the same manner as the amount of iridium per unit area of ​​the anode catalyst layer.

[0036] The anode catalyst layer of the present disclosure may contain components (so-called other components) other than the anode catalyst and ionomer of the present disclosure, as long as the effects are not impaired. Examples of other components include components having catalytic activity other than the anode catalyst of the present disclosure, as well as unreacted components and side reaction components of the raw materials used to produce the anode catalyst of the present disclosure.

[0037] [Anion exchange membrane water electrolysis cell] The anion exchange membrane water electrolysis cell of the present disclosure includes an anode separator, an anode gas diffusion layer, the anode catalyst layer of the present disclosure described above, an electrolyte membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode separator.

[0038] The anode catalyst layer of the present disclosure has been described above, and therefore will not be described here. The anode separator, anode gas diffusion layer, electrolyte membrane, cathode catalyst layer, cathode gas diffusion layer, and cathode separator may be made of materials used in conventionally known water electrolysis cells.

[0039] The anode separator is disposed on the anode gas diffusion layer side. Examples of materials for the anode separator include titanium, stainless steel, and carbon. The anode separator preferably contains titanium from the viewpoint of suppressing oxidation due to oxygen generated on the anode side. The anode separator may be coated with a corrosion-resistant conductive material (so-called coating material) to prevent the anode separator from increasing in resistance due to oxidation. Examples of the coating material include platinum, gold, silver, titanium nitride, titanium carbide, and titanium carbonitride.

[0040] The anode gas diffusion layer may be made of a material that allows fluid to pass through the layer, such as a porous material, a powder sintered material, a fiber sintered material, a metal mesh, or felt. The anode gas diffusion layer may be coated with a corrosion-resistant conductive material (so-called coating material) to prevent the resistance from increasing due to oxidation. Examples of the coating material include platinum, gold, silver, titanium nitride, titanium carbide, and titanium carbonitride.

[0041] The electrolyte membrane may be selected from known anion-exchange membrane-type solid electrolytes used in water electrolysis. Anion-exchange membrane-type solid electrolytes have the property of selectively permeating anions. An example of the electrolyte membrane is an anion-exchange membrane (AEM). The polymer electrolyte membrane is a polymer having anion conductivity due to the presence of ionic groups. The polymer electrolyte membrane may be, for example, a fluorine-based polymer electrolyte membrane or a hydrocarbon-based polymer electrolyte membrane.

[0042] In the present disclosure, representative examples of polymer electrolytes having anion conductivity include commercially available products such as "A-201" (manufactured by Tokuyama Corporation), "AEMION" (registered trademark) (manufactured by Ionomer Innovations, Inc.), "Sustanion" (registered trademark) (manufactured by Dioxide Materials Corporation), and "Fumasep FAA3" (registered trademark) (manufactured by Fumatec Co., Ltd.).

[0043] The electrolyte membrane may be combined with a reinforcing material. By using the reinforcing material, gas leakage and short circuits within the electrodes due to membrane damage are less likely to occur when the electrolyte membrane and the electrodes are joined by, for example, a hot press method.

[0044] Specific examples of reinforcing materials include homogeneous porous films made of fluorine-based polymers such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PVDF (polyvinylidene fluoride), and FEP (tetrafluoroethylene-hexafluoropropylene copolymer); thermoplastic resins such as PE (polyethylene) and PP (polypropylene); and engineering plastics such as PI (polyimide), PSF (polysulfone), PES (polyethersulfone), PEEK (polyetheretherketone), PPSS (polyphenylene sulfide sulfone), PPO (polyphenylene oxide), PEK (polyetherketone), PBI (polybenzimidazole), PPS (polyphenylene sulfide), PPP (polyparaphenylene), PPQ (polyphenylquinoxaline), polybenzoxazole (PBO), polybenzothiazole (PBT), and polyparaphenylene terephthalamide (PPTA).

[0045] The cathode catalyst layer is a layer containing a cathode catalyst. The cathode catalyst converts protons generated by the water electrolysis reaction in the anode catalyst layer of the present disclosure into hydrogen, and may be selected from known catalysts used in water electrolysis. Examples of catalyst components include platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, molybdenum, tungsten, vanadium, alloys thereof, and oxides thereof.

[0046] The cathode catalyst layer may contain a cathode catalyst in which a catalyst component is supported on a carrier. In this case, the catalyst component is preferably supported in a dispersed state on the carrier. The support may be, for example, carbon. Carbon includes carbon black. The cathode catalyst may be in the form of particles.

[0047] The cathode catalyst layer preferably contains an ionomer. The ionomer contained in the cathode catalyst layer has the same meaning as the ionomer contained in the anode catalyst layer of the present disclosure, and preferred embodiments are also the same, so a description thereof will be omitted here.

[0048] The cathode gas diffusion layer may be made of a material that allows fluid to pass through the layer, such as a porous material, a powder sintered material, a fiber sintered material, a metal mesh, or felt.

[0049] The cathode separator is disposed on the cathode gas diffusion layer side. The material of the cathode separator is not particularly limited, and examples thereof include titanium, stainless steel, and carbon.

[0050] The water electrolysis cell of the present disclosure may further include other components. The other components may be selected from known components of water electrolysis cells. Other components include, for example, gaskets and seals.

[0051] The arrangement of each component in the water electrolysis cell of the present disclosure may be determined with reference to known water electrolysis cells. In the water electrolysis cell of the present disclosure, the electrolyte membrane is preferably located between the anode catalyst layer of the present disclosure and the cathode catalyst layer. In the water electrolysis cell of the present disclosure, the electrolyte membrane, the anode catalyst layer of the present disclosure, and the cathode catalyst layer are preferably located between the anode gas diffusion layer and the cathode gas diffusion layer. In the water electrolysis cell of the present disclosure, the anode gas diffusion layer, the anode catalyst layer of the present disclosure, the electrolyte membrane, the cathode catalyst layer, and the cathode gas diffusion layer are preferably located between the anode separator and the cathode separator.

[0052] An example of a water electrolysis cell according to the present disclosure is shown in Fig. 1. Fig. 1 is a schematic cross-sectional view of the water electrolysis cell. As shown in Fig. 1, the water electrolysis cell 100 includes, in order from the top of Fig. 1, an anode separator 60, an anode gas diffusion layer 20, an anode catalyst layer 12, an electrolyte membrane 11, a cathode catalyst layer 13, a cathode gas diffusion layer 30, and a cathode separator 70. Furthermore, in the water electrolysis cell 100, a gasket 40 is disposed between the anode separator 60 and the electrolyte membrane 11, and a gasket 50 is disposed between the cathode separator 70 and the electrolyte membrane 11.

[0053] [Water electrolysis device] The water electrolysis device according to the present disclosure may be a water electrolysis cell stack formed by stacking a plurality of the anion exchange membrane water electrolysis cells according to the present disclosure, or may be a device including the water electrolysis cell stack or the water electrolysis cell according to the present disclosure and other components.

[0054] The other components may be selected from known components of water electrolysis devices. Examples of other components include auxiliary equipment such as a power conditioner, a water pump, an ion exchange resin, a heat exchanger, and a dehumidifier. [Example]

[0055] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples. The matters shown in the following examples may be appropriately changed without departing from the spirit of the present disclosure.

[0056] Example 1 The catalyst species is SrTi 0.67 Ir 0.33 A water electrolysis anode catalyst with a perovskite structure (O3) was synthesized by the Pezzini method. The starting materials were strontium carbonate (SrCO3), titanium tetrabutoxide (C 16 H 36The solids were dissolved in 0.295g of SrCO3, 0.08g of K2IrCl6, 2mL of aqueous nitric acid solution, and 0.28g of citric acid monohydrate (C6H8O7·H2O), and then mixed with 10mL of pure water. After dissolving the solids, the mixture was stirred at room temperature (20°C; the same applies below) for at least 1 hour. The resulting mixed solution was designated Solution A. 16 H 36 0.113 g of O4Ti was weighed out and added to 4 mL of ethylene glycol (C2H6O2), and then mixed and stirred at room temperature for 1 hour. The resulting mixture was designated Solution B. Solution A was added to Solution B, and the mixture was stirred and mixed at 70°C for at least 3 hours using a hot stirrer. The resulting mixture was transferred to a zirconia crucible and heat-treated at 180°C for 12 hours, 200°C for 6 hours, 300°C for 6 hours, 500°C for 3 hours, and 600°C for 6 hours. The powder obtained after the heat treatment was collected and placed in a beaker with 500 mL of 1 M hydrochloric acid solution and stirred for at least 6 hours to remove unreacted components. The resulting mixture was washed with water using a suction filter and then dried in an oven at 60°C to obtain catalyst powder. X-ray diffraction measurements were performed on the resulting catalyst powder, revealing a diffraction pattern consistent with the perovskite structure. The resulting catalyst powder was also analyzed for its constituent elements using energy-dispersive X-ray analysis attached to a field-emission scanning electron microscope. Specifically, the catalyst powder was applied to a carbon tape, and mapping analysis was performed on three image areas at 10,000x magnification. The average elemental concentrations of the constituent elements in each image were evaluated. The molar concentration ratios of the strontium ions at the A site, the titanium ions at the B site, and the iridium ions at the B site, relative to the total molar concentration of all metal ions, were 0.500 mol%, 0.335 mol%, and 0.165 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.67 Ir 0.33 It was confirmed that it contained O3.

[0057] <Example 2> In Example 2, the amount of SrCO3 used was changed to 0.294 g, and 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.056 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.250 mol%, and 0.250 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.5 Ir 0.5 It was confirmed that it contained O3.

[0058] Example 3 In Example 3, the amount of SrCO3 used was changed to 0.340 g, and C 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.042 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.215 mol%, and 0.285 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.43 Ir 0.57 It was confirmed that it contained O3.

[0059] Example 4 In Example 4, a catalyst powder was obtained by the same procedure as in Example 2, except that one of the starting materials, SrCO3, was changed to calcium carbonate (CaCO3) in an amount of 0.198 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of calcium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.250 mol%, and 0.250 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, CaTi 0.5 Ir 0.5 It was confirmed that it contained O3.

[0060] <Example 5> In Example 5, one of the starting materials, SrCO3, was changed to barium carbonate (BaCO3) and the amount used was 0.430 g. 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.068 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of barium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.275 mol%, and 0.225 mol%, respectively. The catalyst obtained by the above steps is BaTi, an oxide having a perovskite structure. 0.55 Ir 0.45 It was confirmed that it contained O3.

[0061] Example 6 In Example 6, one of the starting materials, C 16 H36 O4Ti as tin tetrabutoxide (C 16 H 36 The same procedure as in Example 1 was carried out, except that the amount used was changed to 0.067 g of 0.04Sn, to obtain a catalyst powder. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, tin ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.250 mol%, and 0.250 mol%, respectively. The catalyst obtained by the above process is an oxide having a perovskite structure, SrSn 0.5 Ir 0.5 It was confirmed that it contained O3.

[0062] Example 7 In Example 7, one of the starting materials, C 16 H 36 A catalyst powder was obtained by the same procedure as in Example 1, except that O4Ti was changed to zirconium oxide chloride octahydrate (ZrOCl2·8H2O) in an amount of 0.256 g, the amount of SrCO3 was changed to 0.819 g, the amount of K2IrCl6 was changed to 0.192 g, the amount of C6H8O7·H2O was changed to 4.708 g, the amount of water was changed to 20 mL, and the amount of ethylene glycol was changed to 8 mL. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, zirconium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.335 mol%, and 0.165 mol%, respectively. The catalyst obtained by the above process is an oxide having a perovskite structure, SrZr 0.67 Ir 0.33 It was confirmed that it contained O3.

[0063] Example 8 In Example 8, the same procedure as in Example 7 was carried out to obtain a catalyst powder, except that the amount of SrCO3 used was changed to 0.816 g and the amount of ZrOCl2·8H2O used was changed to 0.128 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to a perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, zirconium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.250 mol%, and 0.250 mol%, respectively. The catalyst obtained by the above process is an oxide having a perovskite structure, SrZr 0.5 Ir 0.5 It was confirmed that it contained O3.

[0064] Example 9 In Example 9, the same procedure as in Example 7 was carried out to obtain a catalyst powder, except that the amount of SrCO3 used was changed to 0.711 g and the amount of ZrOCl2·8H2O used was changed to 0.095 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, zirconium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.215 mol%, and 0.285 mol%, respectively. The catalyst obtained by the above process is an oxide having a perovskite structure, SrZr 0.43 Ir 0.57It was confirmed that it contained O3.

[0065] Example 10 In Example 10, a catalyst powder was obtained by the same procedure as in Example 8, except that one of the starting materials, Sr(NO3)2, was changed to BaCO3 in an amount of 1.090 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of barium ions at the A site, zirconium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.250 mol%, and 0.250 mol%, respectively. The catalyst obtained by the above process is BaZr, an oxide having a perovskite structure. 0.5 Ir 0.5 It was confirmed that it contained O3.

[0066] Example 11 In Example 11, a catalyst powder was obtained in the same manner as in Example 7, except that 0.8224 g of BaCO3, 0.1390 ​​g of CaCO3, 0.1917 g of ZrOCl2·8H2O, and 0.192 g of K2IrCl6 were used as starting materials. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratios of barium ions at the A site, calcium ions at the A site, zirconium ions at the B site, and iridium ions at the B site were 0.375 mol%, 0.125 mol%, 0.300 mol%, and 0.200 mol%, respectively, relative to the total molar concentration of all metal ions. The catalyst obtained by the above steps is Ba, an oxide having a perovskite structure. 0.75 Ca 0.25 Zr 0.6 Ir0.4 It was confirmed that it contained O3.

[0067] <Comparative Example 1> In Comparative Example 1, 0.451 g of BaCO3, 0.337 g of SrCO3, 0.669 g of cobalt nitrate (Co(NO3)2), 0.221 g of iron nitrate (Fe(NO3)2), 50 mL of pure water, 5.763 g of citric acid monohydrate, 10 mL of aqueous nitric acid solution, and 10 mL of ethylene glycol were used as starting materials, and a catalyst powder was obtained by the same procedure as in Example 1, except that the starting materials were heated at 600°C and then at 1000°C for 2 hours. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of barium ions at the A site, strontium ions at the A site, cobalt ions at the B site, and iron ions at the B site, relative to the total molar concentration of all metal ions, was 0.250 mol%, 0.250 mol%, 0.400 mol%, and 0.100 mol%, respectively. The catalyst obtained by the above steps is Ba, an oxide having a perovskite structure. 0.5 Sr 0.5 Co 0.8 Fe 0.2 It was confirmed that it contained O3.

[0068] <Comparative Example 2> In Comparative Example 2, 0.293 g of SrCO3 and C 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that 0.225 g of O4Ti was used. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst, as in Example 1, revealed that the molar concentration ratio of the strontium ion at the A site to the total molar concentration of all metal ions was 0.500 mol %, and the molar concentration ratio of the titanium ion at the B site was 0.500 mol %. From the above, it was confirmed that the obtained catalyst contained SrTiO3, an oxide having a perovskite structure.

[0069] <Comparative Example 3> In Comparative Example 3, the amount of SrCO3 used was changed to 0.287 g, and 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.225 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.475 mol%, and 0.025 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.95 Ir 0.05 It was confirmed that it contained O3.

[0070] <Comparative Example 4> In Comparative Example 4, the amount of SrCO3 used was changed to 0.283 g, and 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.510 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.450 mol%, and 0.050 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.9 Ir 0.1 It was confirmed that it contained O3.

[0071] <Comparative Example 5> In Comparative Example 5, the amount of SrCO3 used was changed to 0.287 g, and 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.225 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.400 mol%, and 0.100 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, SrTi 0.8 Ir 0.2 It was confirmed that it contained O3.

[0072] <Comparative Example 6> In Comparative Example 6, one of the starting materials, SrCO3, was changed to CaCO3 and the amount used was 0.202 g, and C 16 H 36 A catalyst powder was obtained in the same manner as in Example 1, except that the amount of O4Ti used was changed to 0.225 g. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to the perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of calcium ions at the A site, titanium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.400 mol%, and 0.100 mol%, respectively. The catalyst obtained by the above steps is an oxide having a perovskite structure, CaTi 0.8 Ir 0.2 It was confirmed that it contained O3.

[0073] <Comparative Example 7> In Comparative Example 7, the same procedure as in Example 7 was carried out, except that the amount of SrCO3 used was changed to 0.572 g and the amount of ZrOCl2·8H2O used was changed to 0.512 g, to obtain a catalyst powder. X-ray diffraction measurement of the obtained catalyst powder revealed a diffraction pattern attributable to a perovskite structure. Furthermore, analysis of the constituent elements of the obtained catalyst in the same manner as in Example 1 revealed that the molar concentration ratio of strontium ions at the A site, zirconium ions at the B site, and iridium ions at the B site, relative to the total molar concentration of all metal ions, was 0.500 mol%, 0.400 mol%, and 0.100 mol%, respectively. The catalyst obtained by the above process is an oxide having a perovskite structure, SrZr 0.8 Ir 0.2 It was confirmed that it contained O3.

[0074] [evaluation] The catalyst powders containing oxides having a perovskite structure obtained in Examples 1 to 11 and the catalyst powders containing oxides having a perovskite structure obtained in Comparative Examples 1 to 7 were each used as anode catalysts, and the following evaluations were carried out.

[0075] 1. Current Density Measurement The relationship between the current density and voltage of the catalyst was evaluated at room temperature by the rotating disk electrode method. 10 mg of catalyst powder, 0.1 mL of a 5% by mass Nafion dispersion (Sigma-Aldrich) as an ionomer, 0.4 mL of 2-propanol, and 1.5 mL of pure water were weighed and transferred to a glass container and mixed for at least 30 minutes using a homogenizer. 10 μL of the resulting mixed solution was applied to a 5 mm diameter glassy carbon electrode. After drying, the electrode was set using a rotating disk electrode device to form a working electrode. A platinum wire was used as the counter electrode, and an aqueous Ag / AgCl reference electrode was used as the reference electrode. These and the working electrode were placed in a beaker containing 1 M potassium hydroxide aqueous solution. After maintaining the catalyst in an open circuit for 10 minutes or more, 60 cycles of cyclic voltammetry measurements were performed at room temperature in the range of 0.05 V to 1.4 V vs. reversible hydrogen electrode (RHE), at a sweep rate of 100 mV / s, and at a rotation speed of 1,600 rpm (revolutions per minute; hereinafter the same) to perform electrochemical cleaning of the catalyst surface. The voltage was then set to 2 V vs. RHE and maintained for 12 hours, and the current at 1.6 V was measured. The current value was divided by the area of ​​the glassy carbon electrode to determine the current density (unit: mA / cm). 2 The rotation speed during this measurement was 1,600 rpm. The measured current density values ​​and their logarithms are shown in Table 1. The ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B site ions and log{current density (mA / cm 2 )} is shown in Figure 2, and the relationship between the ratio of the amount of ionomer per unit area to the amount of iridium per unit area and log{current density (mA / cm 2 )} is shown in Figure 3.

[0076] The amount of iridium per unit area of ​​the anode catalyst layer and the amount of ionomer per unit area were both measured by the methods described above using a high-resolution ICP optical emission spectrometer (model PS3520VDDII) manufactured by Hitachi High-Tech Science Corporation.

[0077] [Table 1]

[0078] As shown in Table 1, the current density was higher in Examples 1 to 11 than in Comparative Examples 1 to 7. This indicates that the anode catalysts shown in Examples 1 to 11 have better alkali resistance than the anode catalysts shown in Comparative Examples 1 to 7.

[0079] FIG. 2 shows the log{current density (mA / cm) of the anode catalyst layer in Examples 1 to 11 and Comparative Examples 1 to 7, in which a current test was carried out in an alkaline environment. 2 )} and the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in B-site ions in the anode catalyst [molar concentration of iridium ions / total molar concentration of all metal ions contained in B-site ions]. From the examples and comparative examples shown in FIG. 2, the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B site ions in the anode catalyst is defined as X, and the log{current density (mA / cm) of the anode catalyst layer is calculated. 2 )} is Y, the relationship between X and Y is Y=-16.256X 2 +14.002X-1.2686 It was found to be expressed as From the results shown in Figure 2, the log{current density (mA / cm) of the anode catalyst layer 2 )} of the anode catalyst layer is 1.45 or more, the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B site ions in the anode catalyst is in the range of 0.30 to 0.57, and the log{current density (mA / cm 2 )} is 1.50 or more, the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B site ions in the anode catalyst is in the range of 0.31 to 0.55, and the log{current density (mA / cm 2)} is 1.60 or more, the ratio of the molar concentration of iridium ions to the total molar concentration of all metal ions contained in the B site ions in the anode catalyst was found to be in the range of 0.34 to 0.53.

[0080] FIG. 3 shows the log{current density (mA / cm) of the anode catalyst layer in Examples 1 to 11 and Comparative Examples 1 to 7, in which a current test was carried out in an alkaline environment. 2 )} and the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer [amount of ionomer per unit area / amount of iridium per unit area]. From the examples and comparative examples shown in FIG. 3, the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer is defined as P, and the log{current density (mA / cm) of the anode catalyst layer 2 )} is Y, the relationship between P and Y is Y=0.6453P 2 -2.7891P+2.2573 It was found to be expressed as From the results shown in Figure 3, the log{current density (mA / cm) of the anode catalyst layer 2 )} is 1.45 or more, the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer is in the range of more than 0 to 0.32 or less, and the log{current density (mA / cm 2 At threshold 2, where the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer is greater than 0 and less than or equal to 0.29, the log{current density (mA / cm )} of the anode catalyst layer is 1.50 or more. 2 )} is 1.60 or more, the ratio of the amount of ionomer per unit area to the amount of iridium per unit area in the anode catalyst layer is found to be in the range of more than 0 and 0.25 or less. [Explanation of symbols]

[0081] 11: Electrolyte membrane 12: Anode catalyst layer for anion exchange membrane water electrolysis 13: Cathode catalyst layer 20: Anode gas diffusion layer 30: Cathode gas diffusion layer 40: Gasket 50: Gasket 60: Anode separator 70: Cathode separator 100: Anion exchange membrane water electrolysis cell

Claims

1. The perovskite structure has A-site ions containing at least one ion selected from the group consisting of calcium ions, strontium ions, and barium ions, and B-site ions containing tetravalent metal ions and iridium ions, the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions is in the range of 0.30 or more and 0.57 or less, An anode catalyst for anion exchange membrane water electrolysis, in which an oxygen generation reaction according to the following formula (I) occurs in an alkaline solution: 4OH － → 2H ２ O+O ２ +4e － (I)

2. 2. The anode catalyst for anion exchange membrane water electrolysis according to claim 1, wherein the tetravalent metal ions include at least one ion selected from the group consisting of titanium ions, zirconium ions, and tin ions.

3. 2. The anion exchange membrane water electrolysis anode catalyst according to claim 1, wherein the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions is in the range of 0.31 or more and 0.55 or less.

4. 2. The anion exchange membrane water electrolysis anode catalyst according to claim 1, wherein the ratio of the molar concentration of the iridium ions to the total molar concentration of all metal ions contained in the B site ions is in the range of 0.34 to 0.

53.

5. An anion exchange membrane water electrolysis anode catalyst according to any one of claims 1 to 4, and an ionomer, 1. An anode catalyst layer for anion exchange membrane water electrolysis, wherein the ratio of the amount of ionomer per unit area to the amount of iridium per unit area is in the range of more than 0 and not more than 0.

32.

6. 6. The anode catalyst layer for anion exchange membrane water electrolysis according to claim 5, wherein the ratio of the amount of ionomer per unit area to the amount of iridium per unit area is in the range of more than 0 and not more than 0.

29.

7. 6. The anode catalyst layer for anion exchange membrane water electrolysis according to claim 5, wherein the ratio of the amount of ionomer per unit area to the amount of iridium per unit area is in the range of more than 0 and not more than 0.

25.

8. An anion exchange membrane water electrolysis cell comprising: an anode separator; an anode gas diffusion layer; the anode catalyst layer for anion exchange membrane water electrolysis according to claim 5; an electrolyte membrane; a cathode catalyst layer; a cathode gas diffusion layer; and a cathode separator.

9. A water electrolysis cell stack comprising a plurality of the anion exchange membrane water electrolysis cells according to claim 8 stacked one on top of the other.

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