Electrode material, and electrodes, fuel cells, and water electrolysis cells using the same

Abstract

To provide a novel electrode material for fuel batteries that has a high power generation performance and high durability against sharp rise in potential, and also to provide a novel electrode material for water electrolysis cells that has a high water electrolysis performance.SOLUTION: An electrode material has such a structure that at least one kind of noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrode material, and an electrode, a fuel cell, and a water electrolysis cell using the same. [Background technology]

[0002] Fuel cells are devices that generate electricity by electrochemically reacting fuels such as hydrogen or alcohol with oxygen, and are classified into polymer electrolyte fuel cells (PEFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), etc., depending on the electrolyte, operating temperature, etc. For example, polymer electrolyte fuel cells are used in stationary power sources and fuel cell vehicles, and are required to maintain the desired power generation performance over the long term.

[0003] Among these fuel cells, polymer electrolyte fuel cells (PEFCs) use an ion-conductive polymer membrane (ion exchange membrane) as an electrolyte, and generally use an electrode material in which platinum (Pt) is supported on carbon, a conductive material. In PEFCs, hydrogen supply shortages can occur due to water clogging of the fuel flow path or freezing of water. When this occurs, the anode potential rises sharply, causing the cell polarity to reverse, resulting in a polarity reversal state. At the anode in a polarity reversal state, instead of the reaction of hydrogen oxidation, reactions of water decomposition and carbon oxidation (corrosion) supply protons, so the potential instantly exceeds 1.5 V vs RHE, and carbon oxidation (C + 2H2O → CO2 + 4H++ 4e - ) and causes a significant decrease in battery performance. In order to avoid this decrease in battery performance, a conductive oxide such as IrO2 is used as a carrier that does not oxidize and disappear, instead of carbon. 2 A method using a non-electrically conductive inorganic oxide such as TiO2 with a specific surface area of 1 m2 has been proposed (Patent Document 1). 2A method has been proposed in which a thin layer of a precious metal such as Pt and hydrophobic molecules such as Teflon (registered trademark) are supported on SiO2 nanofibers with a density of 1 / g or more (Patent Document 2). Also, a method has been proposed in which catalyst particles, in which metal particles made of platinum or its alloy are supported on the surface of a catalyst support whose main component is SiO2, conductive particles such as graphite, and a proton-conducting material are used as electrodes (Patent Document 3). Furthermore, water electrolysis, the most practical method for producing hydrogen, is the reverse reaction of a fuel cell, in which water is decomposed into hydrogen and oxygen using electricity. Two main water electrolysis methods are used: solid polymer electrolysis and alkaline electrolysis. Of these, solid polymer electrolysis can be operated at a higher current density than alkaline electrolysis, which has the advantage of allowing for system miniaturization. Theoretically, a voltage of 1.23 V or more is required for the water electrolysis reaction under standard conditions (25°C, 1 atmosphere), and water electrolysis cells typically use high voltages of up to about 2.0 V. The anode (oxygen-evolving electrode) in a water electrolysis cell requires a catalyst with oxygen-evolving reaction activity, and iridium is known to have high activity (Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 092568 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-71960 [Patent Document 3] Patent No. 3576108 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-274326 [Patent Document 5] Japanese Patent Application Laid-Open No. 2003-166093 Summary of the Invention [Problem to be solved by the invention]

[0005] Regarding the above-mentioned carbon corrosion that occurs when the potential of a polymer electrolyte fuel cell suddenly rises, there have been reports of electrodes such as those shown in Patent Documents 1 to 3. However, in order to realize fuel cells with even higher performance, it is important to increase the degree of freedom in fuel cell design, and there is a need to develop new electrodes that, when used in polymer electrolyte fuel cells, have high power generation performance and high durability against sudden rises in potential. Furthermore, when using iridium as an anode catalyst in a polymer electrolyte water electrolysis cell, it is desirable to use iridium supported on a carrier from the standpoint of cost, etc. However, because the anode of a polymer electrolyte water electrolysis cell is used at a potential even higher than the potential to which the electrodes of a polymer electrolyte fuel cell are exposed, there are currently few materials that can be used as an iridium carrier and that have excellent conductivity and potential durability. For this reason, only iridium or iridium oxide without a carrier is usually used as a catalyst. Because a certain catalyst volume is required to form the anode, a large amount of iridium is used. However, because iridium is expensive, there is a need to develop an electrode with high water electrolysis performance that can reduce the amount of iridium used.

[0006] In view of the above-described current situation, an object of the present invention is to provide a new electrode material for a fuel cell that has high power generation performance and high durability against a sudden rise in potential, and a new electrode material for a water electrolysis cell that has high water electrolysis performance. [Means for solving the problem]

[0007] The present inventors have discovered that when a material comprising spherical SiO2 supported with a predetermined noble metal and / or its oxide is used as an electrode material for a fuel cell, the electrode has high power generation performance and high durability against a sudden rise in potential, and when used as an electrode material for a water electrolysis cell, the cell has high water electrolysis performance. Furthermore, the present inventors have discovered a suitable method for producing such an electrode material, which has led to the completion of the present invention.

[0008] That is, the present invention is an electrode material characterized by having a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2.

[0009] The at least one noble metal selected from Ru, Ir, Rh and Pd is preferably Ru and / or Ir.

[0010] The electrode material preferably has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO, and then Pt and / or its oxide is further supported.

[0011] The electrode material is preferably an electrode material for a fuel cell or a water electrolysis cell.

[0012] The present invention also relates to an electrode made from the electrode material of the present invention.

[0013] The present invention also relates to a fuel cell comprising the electrode of the present invention.

[0014] The present invention also relates to a water electrolysis cell comprising the electrode of the present invention.

[0015] The present invention also provides a method for producing the electrode material of the present invention, comprising the steps of: The production method is also a method for producing an electrode material, characterized by including a step of supporting at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide on spherical SiO2.

[0016] The present invention further provides a method for producing the electrode material of the present invention, comprising the steps of: The production method includes a step (1) of supporting at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide on spherical SiO2; The method for producing an electrode material is characterized by comprising, after the step (1), a step (2) of supporting Pt and / or an oxide thereof. [Effects of the Invention]

[0017] The electrode material of the present invention is a material capable of sufficiently withstanding high potentials and capable of forming highly conductive electrodes. Therefore, it is extremely useful as a conductive material for use in electrodes of fuel cells such as polymer electrolyte fuel cells, water electrolysis cells, solar cells, transistors, and displays such as liquid crystal displays, as well as in antistatic materials and heat-shielding materials. It is particularly useful as a material for electrodes of polymer electrolyte fuel cells or polymer electrolyte water electrolysis cells. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing the results of electron microscope observation of spherical SiO 2 (Sciqas 0.15 μm) used in Examples 1 to 3 and 7 and Comparative Example 1. FIG. [Figure 2] FIG. 1 shows the results of electron microscope observation of spherical SiO2 (Sciqas 0.4 μm) used in Examples 4 and 8. [Figure 3] FIG. 10 shows the results of electron microscope observation of spherical SiO2 (Sciqas 0.05 μm) used in Example 5. [Figure 4] FIG. 1 shows the results of electron microscope observation of spherical SiO2 (Quatron SP-03F) used in Example 6. [Figure 5] FIG. 1 shows the results of electron microscope observation of non-spherical SiO 2 (Nipsil EL) used in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description and can be appropriately modified and applied within the scope that does not change the gist of the present invention.

[0020] 1. Electrode material The electrode material of the present invention has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2. When SiO2 has a spherical shape, when an electrode is formed, the electrode material has the appropriate density required for electron conduction and the appropriate voids suitable for the diffusion of reaction gases and moisture, allowing the properties of the electrode material to be fully exhibited. The electrode material of the present invention is formed by supporting at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide on such spherical SiO2. By using this material, an electrode having high power generation performance and high durability against sudden increases in potential can be obtained. Here, spherical SiO2 refers to SiO2 having a circularity of 0.7 or more, as determined by the following formula: The circularity takes a value between 0 and 1, with values closer to 1 indicating a closer circle. The circularity of spherical SiO2 is preferably 0.75 or more, and more preferably 0.80 or more. (Circularity) = 4 × π (area of particle) ÷ (perimeter of particle) 2 If the particle contains holes, the area of the holes is included in the particle area. The area and perimeter of the particle can be calculated using the image analysis software WinROOF.

[0021] The above SiO2 has a specific surface area of 1m 2 / g or more, 100m 2 / g or less. By supporting at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide, or Pt and / or its oxide, which will be described later, on spherical SiO2 having such a specific surface area and covering the surface of the SiO2 particles, the effect of supporting these can be more fully exhibited. Furthermore, by using such spherical SiO2, the electrode can have higher performance. The specific surface area of SiO2 is more preferably 5 m 2 / g or more, 80m 2 / g or less, and more preferably 10m 2 / g or more, 60m 2 / g or less. The specific surface area of SiO2 can be measured by the method described in the examples below.

[0022] The SiO2 preferably has an average particle size of 0.01 to 1.0 μm. By using SiO2 with such particle sizes and coating the SiO2 particle surfaces with at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide, or with Pt and / or its oxide, as described below, the effects of supporting these metals can be more fully exhibited. Furthermore, by using such spherical SiO2, the electrode can have higher performance. The average particle size of SiO2 is more preferably 0.02 to 0.8 μm, and even more preferably 0.03 to 0.5 μm. The average particle size of SiO2 can be measured by averaging the particle sizes of 40 randomly selected particles in an image taken with an electron microscope.

[0023] The at least one noble metal and / or its oxide selected from Ru, Ir, Rh, and Pd may be any of these elements, and may be either a metal or an oxide thereof, but is preferably Ru and / or Ir and / or their oxides. When any of these is supported on SiO2, an electrode made from the resulting electrode material will have better power generation performance and durability against sudden increases in potential. More preferably, it is Ru and / or its oxide.

[0024] The amount of at least one noble metal and / or its oxide selected from Ru, Ir, Rh, and Pd supported in the electrode material of the present invention is preferably 5% by mass or more relative to 100% by mass of the electrode material. With such a supported amount, the effect of supporting these noble metals and / or their oxides is more fully exhibited, and the electrode produced from the electrode material exhibits higher performance. The supported amount is more preferably 10% by mass or more relative to 100% by mass of the electrode material, and even more preferably 20% by mass or more relative to 100% by mass of the electrode material. While a larger amount is preferable, it is typically 60% by mass or less relative to 100% by mass of the electrode material. In the electrode material of the present invention, when two or more kinds of noble metals selected from Ru, Ir, Rh, and Pd and / or oxides thereof are supported, it is preferable that the total amount of the two or more kinds of noble metals and / or oxides thereof supported is in the above-mentioned ratio.

[0025] The electrode material of the present invention preferably has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2, and then Pt and / or its oxide is further supported on the noble metal. When such an electrode material is used, the electrode using the electrode material has better power generation performance and durability against a sudden rise in potential.

[0026] When the electrode material of the present invention is formed by supporting at least one noble metal and / or its oxide selected from Ru, Ir, Rh, and Pd on spherical SiO2, and then further supporting Pt and / or its oxide, the amount of Pt and / or its oxide supported is preferably 5% by mass or more relative to 100% by mass of the electrode material. With such a supported amount, the effect of supporting Pt and / or its oxide is more fully exhibited, and the electrode fabricated from the electrode material exhibits higher performance. The supported amount is more preferably 8% by mass or more relative to 100% by mass of the electrode material, and even more preferably 10% by mass or more relative to 100% by mass of the electrode material. Although a larger amount is preferable, the supported amount is typically 50% by mass or less relative to 100% by mass of the electrode material.

[0027] In the electrode material of the present invention, it is preferable that a material consisting only of carbon is not present between the at least one noble metal and / or oxide thereof selected from Ru, Ir, Rh, and Pd supported on the spherical SiO2 and the Pt and / or oxide thereof supported thereafter. If this material is present, the voltage after high potential holding described below may decrease. Furthermore, it is preferable that an ion-conductive resin is not present between the at least one noble metal and / or oxide thereof selected from Ru, Ir, Rh, and Pd supported on the spherical SiO2 and the Pt and / or oxide thereof supported thereafter. If this material is present, the initial voltage described below may decrease.

[0028] When the electrode material of the present invention is used as a material for electrodes of fuel cells or water electrolysis cells, it is possible to obtain electrodes that have high power generation or water electrolysis performance and high durability against sudden increases in potential. The present invention also includes an electrode made from the electrode material of the present invention, and a fuel cell or water electrolysis cell including the electrode. Because the electrode made using the electrode material of the present invention has high durability against a sudden rise in potential, it is suitable as an electrode material for use in a polymer electrolyte fuel cell or a polymer electrolyte water electrolysis cell, which are fuel cells and water electrolysis cells in which a sudden rise in potential may occur. The electrode material of the present invention can be used as an electrode material for various gas electrolysis cells such as CO2 and NH3 gas electrolysis cells, solar cells, transistors, liquid crystal and other display devices, and can also be suitably used as an electrically conductive material for antistatic materials, heat ray shielding materials, etc., in addition to fuel cells and water electrolysis cells.

[0029] 2. Manufacturing method of electrode material The method for producing the electrode material of the present invention having a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO is not particularly limited as long as such a structure can be obtained, but the following first and second production methods are preferred. (First manufacturing method) This method involves carrying out the following steps to produce spherical SiO2 carrying at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide (hereinafter also referred to as noble metal 1-supported SiO2), including a first step of adding an aqueous solution of at least one noble metal salt selected from Ru, Ir, Rh, and Pd to a spherical SiO2 slurry to obtain mixed solution 1, a second step of adjusting the pH of mixed solution 1 obtained in the first step to 5 to 9, and then separating the precipitate, and a third step of calcining the precipitate obtained in the second step. (Second manufacturing method) A method for producing SiO2 supported on precious metal 1, comprising the steps of: a first step of adding an aqueous solution of at least one precious metal salt selected from Ru, Ir, Rh, and Pd to a spherical SiO2 slurry to obtain mixed solution 1; a second step of adding a reducing agent to mixed solution 1 obtained in the first step to precipitate particles of at least one precious metal selected from Ru, Ir, Rh, and Pd, and separating the resulting precipitate; and a third step of calcining the precipitate obtained in the second step.

[0030] In either the first or second manufacturing method, the first to third steps may be repeated multiple times to support particles of at least one precious metal selected from Ru, Ir, Rh, and Pd on the spherical SiO2 multiple times. When repeated multiple times, the same salt of the precious metal may be used, or different salts of the precious metal may be used. Furthermore, the third step may not be performed if necessary.

[0031] Furthermore, among the electrode materials of the present invention, those having a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2, and then Pt and / or its oxide is further supported thereon are not particularly limited to the production method as long as such a structure can be obtained, but it is preferable to further subject the noble metal-supported SiO2 slurry obtained by the above-mentioned first or second production method to the following third or fourth production method. (Third manufacturing method) This method comprises the steps of: a first step of adding a Pt salt aqueous solution to a slurry of SiO2 carrying precious metal 1 obtained by the first or second manufacturing method to obtain mixed solution 2; a second step of adjusting the pH of mixed solution 2 obtained in the first step to 5 to 9, and then separating the precipitate; and a third step of calcining the precipitate obtained in the second step. (Fourth manufacturing method) This method includes a first step of adding a Pt salt aqueous solution to a slurry of precious metal 1-supported SiO2 obtained by the first or second manufacturing method to obtain a mixed solution 2, a second step of precipitating Pt particles from the mixed solution 2 obtained in the first step using a reducing agent and separating the resulting precipitate, and a third step of calcining the precipitate obtained in the second step.

[0032] In either the third or fourth production method, the first to third steps may be repeated multiple times to support Pt and / or its oxide particles on the spherical SiO2 multiple times. Furthermore, the third step may not be performed if necessary.

[0033] It is preferable not to include a step of coating the electrode material of the present invention, which has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2 with a material composed only of carbon, before carrying out the third and fourth manufacturing methods. Including this step may result in a decrease in the voltage after high potential holding, as described below. It is also preferable not to include a step of coating the electrode material of the present invention, which has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or its oxide is supported on spherical SiO2 with an ion-conductive resin, before carrying out the third and fourth manufacturing methods. Including this step may result in a decrease in the initial voltage, as described below.

[0034] Examples of the salt of at least one precious metal selected from Ru, Ir, Rh, and Pd used in the first step of the first and second production methods and the Pt salt used in the first step of the third and fourth production methods include inorganic acid salts such as chlorides, sulfates, nitrates, and phosphates, organic acid salts such as acetates and oxalates, and dispersion solutions of nano-sized Ru, Ir, Rh, Pd, Pt, etc. Among these, chloride solutions, nitrate solutions, etc. are preferred.

[0035] In the second step of the first and third production methods, the pH of the mixed aqueous solutions 1 and 2 may be adjusted to 5 to 9, but in order to generate a precipitate more sufficiently, the pH is preferably 6 to 8. More preferably, it is 6.5 to 7.5. In the second step, the temperature of the mixed aqueous solution when adjusting the pH to 5 to 9 is preferably 50 to 100°C, more preferably 60 to 80°C, from the viewpoints of the rate of precipitation of hydroxides of at least one noble metal selected from Ru, Ir, Rh, and Pd, or Pt, and workability.

[0036] In the third step of the first and second production methods, the temperature for calcining the precipitate is not particularly limited as long as the precious metal hydroxide precipitate obtained in the second step of the first production method or the precipitate containing a precipitate of a precious metal element and SiO obtained in the second step of the second production method is sufficiently calcined, but is preferably 200 to 750°C, more preferably 250 to 600°C, and even more preferably 300 to 500°C. The calcination time is not particularly limited as long as the calcination is carried out sufficiently, but is preferably 1 to 8 hours, more preferably 1.5 to 6 hours, and even more preferably 2 to 4 hours.

[0037] In the third step of the third and fourth production methods, the temperature for calcining the precipitate is not particularly limited as long as the Pt hydroxide precipitate obtained in the second step of the third production method and the precipitate containing the Pt simple substance precipitate and the noble metal-supported SiO2 obtained in the second step of the fourth production method are sufficiently calcined, but is preferably 50 to 900°C, more preferably 100 to 700°C, and even more preferably 150 to 600°C. The calcination time is not particularly limited as long as the calcination is carried out sufficiently, but is preferably 0.1 to 6 hours, more preferably 0.5 to 5 hours, and even more preferably 1 to 4 hours. The firing is preferably carried out in an atmosphere of a firing gas, such as N2 gas or H2 gas, which may be mixed in any ratio.

[0038] The second and fourth production methods involve reducing a precious metal using a reducing agent. The reducing agent is not particularly limited, but examples include hydrazine chloride, hydrazine, sodium borohydride, alcohol, hydrogen, sodium thiosulfate, citric acid, sodium citrate, L-ascorbic acid, formaldehyde, ethylene, and carbon monoxide. Among these, ethanol is preferred as the reducing agent.

[0039] In the first step of the first and third production methods, a reduction treatment may be carried out as needed by adding a reducing agent to the mixed solution 1. By carrying out the reduction treatment, the valence of the noble metal salt can be adjusted to form a precipitate. The reducing agent may be the same as those used in the second and fourth production methods, and among them, hydrazine chloride is preferred. The amount of the reducing agent to be added is not particularly limited, but is preferably 0.1 to 1 times the molar equivalent of the noble metal contained in the mixed solution 1.

[0040] The manufacturing method of the electrode material may include other steps in addition to the steps described above, such as a step of washing the precipitate with water, a step of drying the precipitate, a step of pulverizing the precipitate, a step of classifying the precipitate, etc., after separating the precipitate in the second step of the first to fourth manufacturing methods and before firing the precipitate in the next step. [Example]

[0041] Specific examples are given below to explain the present invention in detail, but the present invention is not limited to only these examples. Unless otherwise specified, “%” and “wt%” mean “mass %”. The measurement methods for each physical property are as follows.

[0042] <Pt loading, Ir loading, Ru loading> Using a scanning fluorescence X-ray analyzer ZSX PrimusII (manufactured by Rigaku Corporation), the Pt content in the sample was measured, and the Ir loading and Ru loading were calculated. <Specific surface area (BET-SSA)> In accordance with the provisions of JIS Z8830 (2013), after the sample was heat-treated at 200 °C for 60 minutes in a nitrogen atmosphere, the specific surface area (BET-SSA) was measured using a specific surface area measuring device (manufactured by Mountech Co., Ltd., trade name “Macsorb HM-1220”). <Circularity> The SiO2 particles were observed with an electron microscope, and the area and perimeter of the particles were determined from the particle images using image analysis software WinROOF, and the circularity was determined by the following formula. When the particles contained holes, the area of the holes was also included in the area of the particles. (Circularity) = 4×π (area of the particles) ÷ (perimeter of the particles) 2 <Initial power generation test of membrane electrode assembly> The membrane electrode assembly was used as the anode side, with a Pt coating of 0.2 mgPt / cm 2 The Pt-supported carbon electrode was used as the cathode side, and the membrane electrode assembly was incorporated into a single cell (manufactured by Miklab Co., Ltd., electrode area 1 cm × 1 cm, Au 10 μm plated Cu separator straight flow path specification). Using a PEFC single cell evaluation device (manufactured by Toyo Technica Co., Ltd.), the cell temperature was set to 80 °C, the anode side was humidified at 77 °C with 100% H2 at 500 ml / min, the cathode side was humidified at 77 °C with 20% O2 / N2 at 2000 ml / min, and the voltage was swept from the open circuit voltage to 0.2 V, and the voltage and cell resistance at the time of 1.0 A / cm 2 were measured. <Power generation test of membrane electrode assembly after high potential holding> After the initial power generation test, the single cell was inverted, and the cell temperature was set to 80°C, the anode side was set to 77°C and humidified with 100% H2500ml / min, and the cathode side was set to 77°C and humidified with 100% N2500ml / min. After applying 1.7V for 10 minutes, the single cell was inverted and the power generation test was performed again, achieving a current of 1.0A / cm 2 The voltage at that point was measured. <Membrane electrode assembly water electrolysis current density measurement> The electrode using the membrane electrode assembly prepared in the examples and comparative examples was placed on the anode side, with a Pt basis weight of 0.2 mg Pt / cm 2 The Pt-loaded carbon electrode was placed on the cathode side and incorporated into a single cell (manufactured by Miklab, electrode area 1cm x 1cm, Au 10μm plated Cu separator, straight flow path specification) together with a gas diffusion layer (SIGRACET 28BA manufactured by SGL Carbon). Using a PEFC single cell evaluation device (manufactured by Toyo Corporation), the cell temperature was set to 70°C, the anode side was set to 80°C and humidified with 4% H2 / N2 at 1L / min, and the cathode side was set to 80°C and humidified with 100% N2 at 1L / min. The voltage was swept from 1.0V to 2.0V, and the current density at 1.5V was measured. <Electron microscope photograph observation> Observation was carried out using a field emission scanning electron microscope JSM-7000F (manufactured by JEOL Ltd.).

[0043] Example 1 (1) Preparation of Ru-loaded SiO2 powder 8.0 g of spherical SiO2 (product name "Sciqas" manufactured by Sakai Chemical Industry Co., Ltd., particle size 0.15 μm) and 1600 ml of ion-exchanged water were weighed into a beaker and mixed with stirring to obtain SiO2 slurry 1. In another beaker, a ruthenic chloride solution (8.369 mass % as Ru, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was diluted with ion-exchanged water to 2.2 mass % to prepare (this is referred to as "Ru aqueous solution 1"). While stirring the SiO2 slurry 1, 90.9 g of the above Ru aqueous solution 1 was added, and the mixture was stirred and mixed while heating and maintaining the liquid temperature at 70°C. Furthermore, a 1.0 mol / L potassium hydroxide aqueous solution was added dropwise to adjust the pH to 7, and the mixture was heated and maintained at 70°C for 1 hour. Then, following standard procedures, the mixture was filtered, washed with water, and dried to evaporate all of the water. The entire amount of the resulting powder was placed in an alumina boat, heated to 450°C in an electric furnace over 135 minutes, maintained at 450°C for 4 hours, and then naturally cooled to room temperature to obtain Ru-supported SiO2 powder 1. (2) Preparation of Pt and Ru-loaded SiO2 powder 7.0 g of the obtained Ru-supported SiO2 powder 1 and 778 g of ion-exchanged water were weighed into a beaker and mixed with stirring to obtain Ru-supported SiO2 slurry 1. In another beaker, 35.4 g of an aqueous solution (referred to as "Pt aqueous solution 1") prepared by diluting a chloroplatinic acid solution (15.343 mass% as Pt, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) with ion-exchanged water to a concentration of 2.2 mass% was added to 0.2 g of hydrazine chloride (manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Hydrazine Dihydrochloride") and stirred to prepare a mixture (referred to as "mixed Pt aqueous solution 1"). While stirring the Ru-loaded SiO2 slurry 1, the above-mentioned mixed Pt aqueous solution 1 prepared in a separate beaker was added, and then the mixture was stirred and mixed while heating and maintaining the liquid temperature at 70 °C. Furthermore, 1.0 mol / L of sodium hydroxide aqueous solution was added dropwise to adjust the pH to 7, and the mixture was heated and maintained at 70 °C for 1 hour. It was then filtered, washed with water, and dried according to standard methods to evaporate all water. The entire amount of the obtained powder was placed in an alumina boat, and while passing 100 vol% hydrogen at 400 mL / min in an atmosphere furnace, the temperature was raised to 560 °C over 60 minutes, and the mixture was maintained at 560 °C for 3 hours, after which it was naturally cooled to room temperature to obtain Pt, Ru-loaded SiO2 powder 1. (3) Fabrication of membrane electrode assembly 0.2 g of the obtained Pt, Ru-supported SiO2 powder 1, 168 μL of 20 mass% Nafion solution (Sigma-Aldrich), 120 μL of t-butyl alcohol (Wako Pure Chemical Industries, Ltd.), 24 μL of ion-exchanged water, and 1.4 g of 2 mmφ ZrO2 beads were placed in a screw tube and dispersed for 150 minutes using an ultrasonic cleaner to obtain Pt, Ru-supported SiO2 ink 1. 40 μL of the obtained Pt, Ru-supported SiO2 ink 1 was dropped onto a Teflon (registered trademark) sheet, coated using a bar coater, and then naturally dried to obtain a Pt, Ru-supported SiO2 sheet 1 with a Pt usage amount of 0.05 mg Pt / cm 2 ) was obtained. 0.02 g of commercially available 50% by mass Pt-loaded carbon (manufactured by NE Chemcat Corporation), 61 μL of 20% by mass Nafion solution (manufactured by Sigma-Aldrich Corporation), 179 μL of t-butyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.), 89 μL of ion-exchanged water, and 1.6 g of 2 mm diameter ZrO2 beads were placed in a screw tube and dispersed for 150 minutes using an ultrasonic cleaner to obtain Pt-loaded carbon ink 1. 40 μL of the obtained Pt-supported carbon ink 1 was dropped onto a Teflon (registered trademark) sheet, coated using a bar coater, and then naturally dried to obtain Pt-supported carbon sheet 1 (Pt usage amount 0.2 mg Pt / cm 2 ) was obtained. An electrolyte membrane (manufactured by DuPont, product name NR-212) was cut to a size of 3 cm x 3 cm, and then a RuIr-supported titanium suboxide sheet 1 and a Pt-supported carbon sheet 1 were each cut to a size of 1 cm x 1 cm. The Pt, Ru-supported SiO2 sheet 1, electrolyte membrane, and Pt-supported carbon sheet 1 were stacked in this order and hot-pressed at 140°C for 6 minutes using a heated hydraulic press (manufactured by Toyo Seiki Seisakusho, product name Mini Test Press MP-WNH) with a set pressure of 1 MPa. Thereafter, the Teflon (registered trademark) sheets were peeled off from the Pt, Ru-supported SiO 2 sheet 1 and the Pt-supported carbon sheet 1 to obtain a membrane electrode assembly 1.

[0044] Example 2 A Pt and Ru-supported SiO powder 2 was obtained in the same manner as in Example 1, except that the amount of Ru aqueous solution 1 added to the SiO slurry 1 in (1) Preparation of Ru-supported SiO powder in Example 1 was changed to 155.8 g. The obtained Pt and Ru-supported SiO powder 2 was used to obtain a membrane electrode assembly 2.

[0045] Example 3 A Pt- and Ru-supported SiO powder 3 was obtained in the same manner as in Example 1, except that the amount of Ru aqueous solution 1 added to the SiO slurry 1 in (1) Preparation of Ru-supported SiO powder in Example 1 was changed to 363.6 g. Furthermore, a membrane electrode assembly 3 was obtained using the obtained Pt- and Ru-supported SiO powder 3.

[0046] Example 4 A Pt and Ru-supported SiO powder 4 was obtained in the same manner as in Example 2, except that in (1) Preparation of Ru-supported SiO powder in Example 2, spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.15 μm) was used instead of spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.40 μm). In addition, a membrane electrode assembly 4 was obtained using the obtained Pt and Ru-supported SiO powder 4.

[0047] Example 5 A Pt and Ru-supported SiO powder 5 was obtained in the same manner as in Example 3, except that in (1) Preparation of Ru-supported SiO powder in Example 3, spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.15 μm) was used instead of spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.05 μm). Furthermore, a membrane electrode assembly 5 was obtained using the obtained Pt and Ru-supported SiO powder 5.

[0048] Example 6 A Pt and Ru-supported SiO powder 6 was obtained in the same manner as in Example 2, except that the spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.15 μm) in (1) Preparation of Ru-supported SiO powder was changed to spherical SiO (manufactured by Fuso Chemical Industry Co., Ltd., product name "Quatron SP-03F") powder. The obtained Pt and Ru-supported SiO powder 6 was used to obtain a membrane electrode assembly 6.

[0049] Example 7 In (1) Preparation of Ru-supported SiO2 powder in Example 1, the addition of 90.9 g of Ru aqueous solution 1 to SiO2 slurry 1 was changed to the addition of 90.9 g of a chloroiridic acid solution (8.604 mass% Ir, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) diluted with ion-exchanged water to 2.2 mass% (hereinafter referred to as "Ir aqueous solution 1") and a mixture of 0.55 g of hydrazine chloride (hereinafter referred to as "mixed Ir aqueous solution 1") to SiO2 slurry 1. Ir-supported SiO2 powder 1 and Pt, Ir-supported SiO2 powder 1 were obtained in the same manner as in Example 1. Furthermore, a membrane electrode assembly 7 was obtained using the obtained Pt, Ir-supported SiO2 powder 1.

[0050] Example 8 In Example 4, (1) the Ru aqueous solution 1 in the preparation of the Ru-supported SiO powder was changed to the Ir aqueous solution 1, and (2) the mixed Pt aqueous solution 1 in the preparation of the Pt, Ru-supported SiO powder was replaced with the mixed Pt aqueous solution 2 prepared by stirring and mixing 136.4 g of the Pt aqueous solution 1 and 0.81 g of hydrazine hydrochloride. The Pt, Ir-supported SiO powder 2 was obtained in the same manner as in Example 4. The obtained Pt, Ir-supported SiO powder 2 was used to obtain a membrane electrode assembly 8.

[0051] Example 9 Pt, Ru, and Ir-supported SiO powder 1 was obtained in the same manner as in Example 1, except that 103.9 g of Ru aqueous solution 1 was added in (1) Preparation of Ru-supported SiO powder in Example 1, and 51.9 g of Ir aqueous solution 1 in Example 7 was added at the same time. Furthermore, a membrane electrode assembly 9 was obtained using the obtained Pt, Ru, and Ir-supported SiO powder 1.

[0052] Example 10 A mixture of 79.5 g of Ir aqueous solution 1 and 0.48 g of hydrazine chloride (referred to as "mixed Ir aqueous solution 2") was prepared. Example 1 (2) Ir-supported SiO2 powder 2 was obtained in the same manner as in Example 1 (2), except that in the preparation of Pt, Ru-supported SiO2 powder, the Ru-supported SiO2 powder was changed to the Ir-supported SiO2 powder 1 obtained in Example 7, and the mixed Pt aqueous solution 1 was changed to the mixed Ir aqueous solution 2 prepared above. In addition, the obtained Ir-supported SiO2 powder 2 was used to prepare a membrane electrode assembly 10 (Ir usage amount 0.1 mgIr / cm). 2 ) was obtained.

[0053] Example 11 A mixture of 79.5 g of Ru aqueous solution and 0.91 g of hydrazine chloride (referred to as "mixed Ru aqueous solution 1") was prepared. Example 1 (2) In the preparation of Pt, Ru-supported SiO2 powder, the Ru-supported SiO2 powder was changed to the Ir-supported SiO2 powder 1 obtained in Example 7, and the mixed Pt aqueous solution 1 was changed to the mixed Ru aqueous solution 1 prepared above. Ru, Ir-supported SiO2 powder 1 was obtained in the same manner as in Example 1 (2). In addition, a membrane electrode assembly 11 was obtained using the obtained Ru, Ir-supported SiO2 powder 1.

[0054] Comparative Example 1 A Pt-supported SiO2 powder of Comparative Example 1 was obtained in the same manner as in Example 1, except that Ru support in Example 1 was omitted. In addition, a membrane electrode assembly of Comparative Example 1 was obtained using the obtained Pt-supported SiO2 powder.

[0055] Comparative Example 2 A Pt and Ru-supported SiO powder of Comparative Example 2 was obtained in the same manner as in Example 2, except that the spherical SiO (manufactured by Sakai Chemical Industry Co., Ltd., product name "Sciqas," particle size 0.15 μm) in Example 2 was changed to non-spherical SiO (manufactured by Tosoh Silica Corporation, product name "Nipsil EL"), and a membrane electrode assembly of Comparative Example 2 was obtained using the obtained Pt and Ru-supported SiO powder 8.

[0056] Comparative Example 3 A membrane / electrode assembly of Comparative Example 3 was obtained in the same manner as in Example 1, using commercially available 50% by mass Pt-supported carbon (manufactured by NE Chemcat Corporation).

[0057] Comparative Example 4 A membrane / electrode assembly of Comparative Example 4 was produced in the same manner as in Example 10, except that iridium black (manufactured by Alfa Aesar) was used instead of the Ir-supported SiO2 powder 2 of Example 10.

[0058] The amount of precious metal supported, the specific surface area, and the circularity of the SiO2 powders used were measured using the methods described above for the precious metal-supported SiO2 powders obtained in Examples 1 to 11 and Comparative Examples 1 and 2. Furthermore, initial power generation tests and power generation tests after high potential holding were conducted using the membrane electrode assemblies obtained in Examples 1 to 11 and Comparative Examples 1 to 3. The results are shown in Table 1. Furthermore, water electrolysis current density measurements were conducted using the membrane electrode assemblies obtained in Examples 10 and 11 and Comparative Example 4. The results are shown in Table 2. Furthermore, electron microscope observation results for the spherical SiO2 and non-spherical SiO2 used in the examples and comparative examples are shown in Figures 1 to 5.

[0059] [Table 1] Carrier: A: Spherical SiO2 (Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.15 μm) B: Spherical SiO2 (Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.4 μm) C: Spherical SiO2 (Sakai Chemical Industry Co., Ltd., product name "Sciqas", particle size 0.05 μm) D: Spherical SiO2 (Fuso Chemical Co., Ltd. product name "Quatron SP-03F") E: Non-spherical SiO2 (manufactured by Tosoh Silica Corporation, product name "Nipsil EL")

[0060] [Table 2]

[0061] From the results in Table 1, it was confirmed that the membrane electrode assemblies of Examples 1 to 11 obtained from the electrode material of the present invention had high initial voltage, low cell resistance, and showed high voltage values even after maintaining a high potential, and therefore had high power generation performance and high durability against high potential, and were effective as electrode materials. The voltage difference between Example 9 and Comparative Example 2 was 20 mV (0.02 W as power), and this measurement was performed on an electrode area of 1 cm 2 However, in the case of a fuel cell vehicle with an output of approximately 100 kW, hundreds of membrane electrode assemblies with an electrode area more than 1,000 times larger are stacked, resulting in an electrode area more than hundreds of thousands times larger, which results in a difference in power of at least several kW, a very large difference. Furthermore, the results in Table 2 confirm that the membrane electrode assemblies of Examples 10 and 11 obtained from the electrode material of the present invention had a high water electrolysis current density.

Claims

1. Spherical SiO ２ An electrode material characterized by having a structure in which at least one noble metal selected from Ru, Ir, Rh and Pd and / or an oxide thereof is supported directly on a substrate.

2. 2. The electrode material according to claim 1, wherein the at least one noble metal selected from the group consisting of Ru, Ir, Rh, and Pd is Ru and / or Ir.

3. Spherical SiO ２ 3. The electrode material according to claim 1, wherein the electrode material has a structure in which at least one noble metal selected from Ru, Ir, Rh, and Pd and / or an oxide thereof is directly supported on the catalyst, and then Pt and / or an oxide thereof is further supported on the catalyst.

4. 4. The electrode material according to claim 1, which is an electrode material for a fuel cell or a water electrolysis cell.

5. An electrode made from the electrode material according to any one of claims 1 to 4.

6. A fuel cell comprising the electrode according to claim 5.

7. A water electrolysis cell comprising the electrode according to claim 5.

8. A method for producing the electrode material according to claim 1 or 2, comprising: The manufacturing method involves the production of spherical SiO ２ 1. A method for producing an electrode material, comprising the step of directly supporting at least one noble metal selected from Ru, Ir, Rh and Pd and / or an oxide thereof on a support.

9. A method for producing the electrode material according to claim 3, comprising the steps of: The manufacturing method involves the production of spherical SiO ２ a step (1) of directly supporting at least one noble metal selected from Ru, Ir, Rh, and Pd and / or an oxide thereof on the catalyst; The method for producing an electrode material comprises, after the step (1), a step (2) of supporting Pt and / or an oxide thereof.

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