WO2013105292A1 - 酸素還元触媒およびその製造方法 - Google Patents
酸素還元触媒およびその製造方法 Download PDFInfo
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- WO2013105292A1 WO2013105292A1 PCT/JP2012/068343 JP2012068343W WO2013105292A1 WO 2013105292 A1 WO2013105292 A1 WO 2013105292A1 JP 2012068343 W JP2012068343 W JP 2012068343W WO 2013105292 A1 WO2013105292 A1 WO 2013105292A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9041—Metals or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8647—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites
- H01M4/8652—Inert electrodes with catalytic activity, e.g. for fuel cells consisting of more than one material, e.g. consisting of composites as mixture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9075—Catalytic material supported on carriers, e.g. powder carriers
- H01M4/9083—Catalytic material supported on carriers, e.g. powder carriers on carbon or graphite
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/921—Alloys or mixtures with metallic elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/92—Metals of platinum group
- H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to an oxygen reduction catalyst and a method for producing the same, and more particularly to an oxygen reduction catalyst that provides a fuel cell with excellent initial performance and start / stop durability and a method for producing the same.
- a polymer electrolyte fuel cell is a type in which a solid polymer electrolyte is sandwiched between an anode and a cathode, fuel is supplied to the anode, oxygen or air is supplied to the cathode, and oxygen is reduced at the cathode to extract electricity.
- a fuel cell having Hydrogen or methanol is mainly used as the fuel.
- a layer containing a catalyst is provided on the cathode surface or anode surface of the fuel cell.
- a noble metal is generally used, and among the noble metals, platinum which is stable at a high potential and has high activity is mainly used.
- carbon black has been used as a carrier for supporting the catalytic metal.
- the cathode is temporarily exposed to a high potential, for example, about 1.5 V, during repeated operation of starting and stopping.
- a high potential for example, about 1.5 V
- carbon as a support is oxidatively corroded in the presence of water, causing decomposition and deterioration of the support.
- the power generation performance of PEFC decreases due to the deterioration of the carrier.
- the deterioration of the carrier promotes the aggregation of noble metals, further reducing the power generation performance. Therefore, there has been a demand for a carrier or catalyst that is resistant to high potentials associated with starting and stopping, and a fuel cell electrode catalyst using the same.
- Patent Document 1 describes a catalyst-supporting carrier obtained by carbonizing a raw material containing a nitrogen-containing organic substance and a metal.
- Patent Document 2 discloses a step 1 of obtaining a catalyst precursor solution by mixing a transition metal-containing compound, a nitrogen-containing organic compound and a solvent, a step 2 of removing the solvent from the catalyst precursor solution, and a solid residue of 500 to Including a step 3 of obtaining an electrode catalyst by heat treatment at a temperature of 1100 ° C., wherein a part or all of the transition metal-containing compound is a transition metal element selected from Group 4 and Group 5 elements of the periodic table as a transition metal element
- a fuel cell electrode catalyst manufactured by a manufacturing method characterized in that it is a compound containing M1 is described.
- Patent Document 3 a gas of a compound containing a metal element M selected from the group consisting of titanium, iron, niobium, zirconium, and tantalum, a hydrocarbon gas, a nitrogen compound gas, and an oxygen compound gas are used at 600 to 1600 ° C.
- a catalyst produced by a production method comprising a reaction step is described.
- Patent Document 4 describes a catalyst carrier made of a metal oxynitride containing niobium or the like as a metal.
- JP 2011-115760 A WO2011 / 099493 WO2010 / 126020 WO2009 / 104500 gazette
- An object of the present invention is to provide an oxygen reduction catalyst having a good initial performance and excellent start-stop durability, and solving the problems in the conventional technology. Furthermore, it is providing the manufacturing method.
- the present inventors include composite particles having a structure in which primary particles of a titanium compound are dispersed in a carbon structure, and titanium, carbon, nitrogen, and oxygen are contained.
- the present invention relates to the following [1] to [18], for example.
- An oxygen reduction catalyst comprising composite particles in which primary particles of a titanium compound are dispersed in a carbon structure, When the composite particle has titanium, carbon, nitrogen, and oxygen as constituent elements, and the ratio of the number of atoms of each element is titanium, the ratio of carbon is greater than 2 and 5 or less. The ratio is greater than 0 and 1 or less, the oxygen ratio is 1 or more and 3 or less, An oxygen reduction catalyst characterized in that the intensity ratio (D / G ratio) of the peak intensity of the D band in the Raman spectrum to the peak intensity of the G band is 0.4 to 1.0.
- the composite particles further include at least one element M2 selected from iron, nickel, chromium, cobalt, and manganese, and the ratio of the total number of elements M2 to titanium is 0.3 or less.
- the oxygen reduction catalyst as described.
- the noble metal alloy is an alloy composed of a noble metal and at least one metal selected from iron, nickel, chromium, cobalt, titanium, copper, vanadium and manganese. catalyst.
- a fuel cell electrode comprising the fuel cell catalyst layer according to [9].
- a membrane / electrode assembly comprising a cathode, an anode, and a polymer electrolyte membrane disposed between the cathode and the anode, wherein the cathode catalyst layer and / or the anode catalyst layer is as described in [9].
- a membrane electrode assembly which is the electrode layer for a fuel cell according to the description.
- a fuel cell comprising the membrane electrode assembly according to [11].
- Process 4 And at least one of the titanium-containing compound (1) and the nitrogen-containing organic compound (2) has an oxygen atom, and the oxidation in step 4 has a D / G ratio in the range of 0.4 to 1.0. It adjusts so that it may become.
- the manufacturing method of the oxygen reduction catalyst characterized by the above-mentioned.
- the oxygen reduction catalyst of the present invention has good initial performance and excellent start / stop durability.
- the method for producing an oxygen reduction catalyst of the present invention can produce the oxygen reduction catalyst efficiently.
- FIG. 1 is a schematic diagram of the reactor (1) used in Comparative Example 12.
- 2A is a transmission electron microscope image of the catalyst (1) obtained in Example 1.
- FIG. 2B is a transmission electron microscope image of the catalyst (6) obtained in Example 6.
- FIG. 2C is a transmission electron microscope image of the catalyst (9) obtained in Comparative Example 2.
- FIG. 3 is a powder X-ray diffraction pattern of the catalyst (1) obtained in Example 1.
- FIG. 4 is a diagram showing the relationship between time and voltage, representing the triangular wave potential cycle applied in the start / stop durability test.
- the oxygen reduction catalyst according to the present invention is an oxygen reduction catalyst including composite particles in which primary particles of a titanium compound are dispersed in a carbon structure, When titanium, carbon, nitrogen, and oxygen are included as constituent elements, and the ratio of the number of atoms of each of the elements is titanium, carbon is greater than 2 and less than or equal to 5, nitrogen is greater than 0 and less than or equal to 1, oxygen Is 1 or more and 3 or less,
- the intensity ratio (D / G ratio) of the peak intensity of the D band to the peak intensity of the G band in the Raman spectrum is 0.4 to 1.0.
- the composite particles have titanium, carbon, nitrogen, and oxygen as constituent elements, and may include the second metal element M2.
- the ratio of the number of atoms of carbon, nitrogen, and oxygen is such that the ratio of carbon is greater than 2 and less than or equal to 5, preferably 2.5 to 5, more preferably 3 to 5, when titanium is 1.
- the ratio is greater than 0 and less than or equal to 1, preferably 0.01 to 0.4, more preferably 0.02 to 0.2, and the oxygen ratio is 1 to 3, preferably 1 to 2.5, more preferably 1.2 to 2.2.
- the ratio of each element is within the above range, the initial performance of the oxygen reduction catalyst is good and the start / stop durability is good.
- the performance of the oxygen reduction catalyst is improved.
- the second metal element M2 include at least one selected from iron, nickel, chromium, cobalt, and manganese. Among these, iron and chromium are preferable from the viewpoint of a balance between cost and catalyst performance. Iron is particularly preferred.
- the ratio of the number of atoms of M2 to titanium is preferably 0.3 or less, more preferably 0.05 to 0.2. When the ratio of the number of atoms of M2 to titanium is within the above range, the performance of the oxygen reduction catalyst is further enhanced.
- the composite particles have an intensity ratio (D / G ratio) of the peak intensity of the D band to the peak intensity of the G band in the Raman spectrum of 0.4 to 1.0, preferably 0.5 to 0.95, more preferably 0.6 to 0.9.
- D / G ratio is 1.0 or less, the initial performance of the oxygen reduction catalyst is good, and the start / stop durability is good. Even if the D / G ratio is less than 0.4, good initial performance and good start / stop durability can be obtained, but it is not effective from the viewpoint of cost effectiveness.
- the composite particles In the X-ray diffraction (XRD) measurement using Cu-K ⁇ rays, the composite particles have the following regions A to D occupying the 2 ⁇ range: A: 26-28 ° B: 35-37 ° C: 40-42 ° D: 53-55 ° It is preferable that the region A has a peak having the maximum intensity among all peaks appearing in the diffraction pattern.
- a catalyst that satisfies such conditions is considered to have rutile titanium oxide as a main phase. When the oxygen reduction catalyst of the present invention satisfies such a condition, the initial performance and the start / stop durability are improved.
- the composite particles preferably have a titanium valence of more than 3 and less than 4 as determined from transmission X-ray absorption fine structure analysis of titanium (transmission method XAFS).
- transmission method XAFS transmission method absorption fine structure analysis of titanium
- the specific surface area calculated by the BET method of the composite particles is preferably 100 m 2 / g or more, more preferably 100 to 600 m 2 / g, still more preferably 150 to 600 m 2 / g.
- the oxygen reduction catalyst of the present invention preferably contains the composite particles, and further has particles made of a noble metal or a noble metal alloy supported on the composite particles.
- the oxygen reduction catalyst of the present invention is a composite catalyst having such particles, it exhibits excellent durability in the start / stop durability test of the fuel cell, and also has good initial performance.
- the noble metal examples include at least one selected from platinum, gold, palladium, iridium, rhodium and ruthenium. Among these, at least one selected from platinum, palladium and iridium is preferable, and platinum is more preferable.
- the noble metal alloy include an alloy of the noble metals or an alloy of the noble metal and at least one metal selected from, for example, iron, nickel, chromium, cobalt, titanium, copper, vanadium, and manganese. it can. Among these, an alloy of platinum and at least one selected from iron, cobalt, and nickel is particularly preferable.
- the amount of the noble metal supported is preferably 5 to 50% by mass, more preferably 20 to 40% by mass as the content in the oxygen reduction catalyst.
- the oxygen reduction catalyst of the present invention contains the precious metal in such a ratio, excellent initial performance is shown in the start / stop durability test of the fuel cell, and the durability is also good.
- the oxygen reduction catalyst of the present invention can be produced, for example, by the following production method.
- the method for producing an oxygen reduction catalyst of the present invention is a method for producing the oxygen reduction catalyst, Step 1 of obtaining a catalyst precursor solution by mixing the titanium-containing compound (1), the nitrogen-containing organic compound (2) and a solvent, Step 2 of removing a solvent from the catalyst precursor solution to obtain a solid residue, Step 3 for performing heat treatment on the solid residue and Step 4 for performing oxidation treatment In which at least one of the titanium-containing compound (1) and the nitrogen-containing organic compound (2) has an oxygen atom.
- the oxygen reduction catalyst is produced by subjecting titanium oxynitride obtained by firing a precursor comprising a titanium-containing organic complex and an organic compound to oxidation treatment, or oxidizing the precursor while firing the precursor. To reduce the amount of amorphous carbon and lower the D / G ratio.
- the production method of the present invention comprises: Step 1 of obtaining a catalyst precursor solution by mixing the titanium-containing compound (1), the nitrogen-containing organic compound (2) and a solvent, Step 2 of removing a solvent from the catalyst precursor solution to obtain a solid residue, The solid residue obtained in Step 2 is heat-treated at a temperature of 700 ° C. to 1400 ° C. to obtain a heat-treated product, and the heat-treated product obtained in Step 3a is oxidized with an oxidizing agent that donates oxygen atoms.
- step 4a wherein at least one of the titanium-containing compound (1) and the nitrogen-containing organic compound (2) has an oxygen atom, and the oxidation in the step 4 has a D / G ratio of 0.4 to 1.0 It is a method for producing an oxygen reduction catalyst, which is adjusted to be in a range.
- a mode in which the step 4a is started after the step 3a is finished will be described below as a first mode.
- step 1 at least a titanium-containing compound (1), a nitrogen-containing organic compound (2) and a solvent are mixed to obtain a catalyst precursor solution.
- a titanium-containing compound (1) a nitrogen-containing organic compound (2) and a solvent are mixed to obtain a catalyst precursor solution.
- a metal element M2 selected from iron, nickel, chromium, cobalt and manganese is used. What is necessary is just to add the compound (henceforth "M2-containing compound (3)") to contain to the said catalyst precursor solution.
- the order of adding these materials is not particularly limited.
- Titanium-containing compound (1) preferably has at least one selected from an oxygen atom and a halogen atom, and specific examples thereof include a titanium complex, and a phosphate, sulfate, nitrate, titanium, Organic acid salts, acid halides (halide hydrolysates), alkoxides, esters, halides, perhalogenates and hypohalites are preferred, more preferably titanium alkoxides, esters, acetylacetone complexes, And at least one selected from the group consisting of chloride, bromide, iodide, acid chloride, acid bromide, acid iodide and sulfate, and more preferably, from the viewpoint of solubility in a solvent in the liquid
- titanium-containing compound (1) Titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetraisobutoxide, titanium tetrapentoxide, titanium tetraacetylacetonate, titaniumoxydiacetylacetonate, tris (acetyl Acetonato) titanium chloride ([Ti (acac) 3 ] 2 [TiCl 6 ]), titanium tetrachloride, titanium trichloride, titanium oxychloride, titanium tetrabromide, titanium tribromide, titanium oxybromide, Examples include titanium compounds such as titanium tetraiodide, titanium triiodide, and titanium oxyiodide. These may be used alone or in combination of two or more.
- the performance of the oxygen reduction catalyst is improved.
- M2-containing compound (3) include Iron (II) chloride, iron (III) chloride, iron (III) sulfate, iron (II) sulfide, iron (III) sulfide, potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, ammonium ferricyanide, iron ferrocyanide , Iron (II) nitrate, iron (III) nitrate, iron (II) oxalate, iron (III) oxalate, iron (II) phosphate, iron (III) phosphate ferrocene, iron (II) hydroxide, water Iron (III) oxide, iron (II) oxide, iron (III) oxide, triiron tetroxide, iron (II) ethylenediaminetetraacetate, iron (II) acetate, iron (II) lactate, iron (III) citrate Iron compounds such as; Nickel chloride (II), nickel sulfate (II), nickel sulfide,
- the nitrogen-containing organic compound (2) used in the production method of the present invention is preferably a compound that can be a ligand capable of coordinating to the titanium atom in the titanium-containing compound (1).
- a compound that can be a bidentate ligand or a tridentate ligand (can form a chelate) is more preferable.
- Nitrogen-containing organic compound (2) may be used alone or in combination of two or more. *
- the nitrogen-containing organic compound (2) is preferably an amino group, nitrile group, imide group, imine group, nitro group, amide group, azide group, aziridine group, azo group, isocyanate group, isothiocyanate group, oxime group, diazo.
- a functional group such as a nitroso group, or a ring such as a pyrrole ring, a porphyrin ring, an imidazole ring, a pyridine ring, a pyrimidine ring, or a pyrazine ring (these functional groups and rings are also collectively referred to as “nitrogen-containing molecular groups”).
- the nitrogen-containing organic compound (2) has a nitrogen-containing molecular group in the molecule, it is considered that the nitrogen-containing organic compound (2) can be strongly coordinated by the titanium atom derived from the titanium-containing compound (1) through the mixing in the step 1. .
- an amino group, an imine group, an amide group, a pyrrole ring, a pyridine ring and a pyrazine ring are more preferable, an amino group, an imine group, a pyrrole ring and a pyrazine ring are more preferable, and an amino group and a pyrazine ring are preferable.
- an amino group, an imine group, a pyrrole ring and a pyrazine ring are more preferable, and an amino group and a pyrazine ring are preferable.
- Is particularly preferable because the activity of the resulting oxygen reduction catalyst is particularly high.
- the nitrogen-containing organic compound (2) is preferably a hydroxyl group, a carboxyl group, a formyl group, a halocarbonyl group, a sulfonic acid group, a phosphoric acid group, a ketone group, an ether group or an ester group. ").
- the nitrogen-containing organic compound (2) has an oxygen-containing molecular group in the molecule, it is considered that the nitrogen-containing organic compound (2) can be coordinated more strongly with the titanium atom derived from the titanium-containing compound (1) through the mixing in Step 1.
- a carboxyl group and a formyl group are particularly preferable because the activity of the obtained oxygen reduction catalyst is particularly high.
- amino acids having an amino group and a carboxyl group, and derivatives thereof are preferable.
- amino acids examples include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, valine, norvaline, glycylglycine, Triglycine and tetraglycine are preferable.
- acylpyrroles such as acetylpyrrole, pyrrolecarboxylic acid, acylimidazoles such as acetylimidazole, carbonyldiimidazole, imidazolecarboxylic acid, pyrazole, acetanilide, pyrazinecarboxylic acid Piperidinecarboxylic acid, piperazinecarboxylic acid, morpholine, pyrimidinecarboxylic acid, nicotinic acid, 2-pyridinecarboxylic acid , 2,4-pyridinedicarboxylic acid, 8-quinolinol, and polyvinylpyrrolidone, and the resulting oxygen reduction catalyst has a high activity, so that it can be a bidentate ligand, specifically pyrrole-2-carboxylic acid.
- Acid imidazole-4-carboxylic acid, 2-pyrazinecarboxylic acid, 2-piperidinecarboxylic acid, 2-piperazinecarboxylic acid, nicotinic acid, 2-pyridinecarboxylic acid, 2,4-pyridinedicarboxylic acid, and 8-quinolinol are preferred. .
- alanine, glycine, lysine, methionine, tyrosine, 2-pyrazinecarboxylic acid, and 2-pyridinecarboxylic acid are more preferable.
- the nitrogen-containing organic compound used in step 1 with respect to the number A of titanium elements in the titanium-containing compound (1) used in step 1
- the ratio (B / A) of the total number of carbon atoms B in (2) is preferably 2 to 200, more preferably 3 to 100, and even more preferably 5 to 50.
- the nitrogen-containing organic compound used in step 1 with respect to the number A of titanium elements in the titanium-containing compound (1) used in step 1
- the ratio (C / A) of the total number of nitrogen atoms C in (2) is preferably 1 to 28, more preferably 2 to 17, and still more preferably 3 to 12.
- Solvent Examples of the solvent include water, acetic acid, acetylacetone, alcohols, and mixed solvents thereof. As alcohols, ethanol, methanol, butanol, propanol and ethoxyethanol are preferable, and ethanol and methanol are more preferable. In order to increase the solubility, it is preferable to contain an acid in the solvent. As the acid, acetic acid, nitric acid, hydrochloric acid, phosphoric acid and citric acid are preferable, and acetic acid and nitric acid are more preferable. These may be used alone or in combination of two or more.
- step 2 the solvent is removed from the catalyst precursor solution obtained in step 1 to obtain a solid residue.
- the method for removing the solvent is not particularly limited, and examples thereof include a method using a spray dryer or a rotary evaporator.
- the composition or aggregation state of the solid residue obtained in Step 2 may be uneven.
- a catalyst having a more uniform particle diameter can be obtained by mixing and crushing the solid residue and using a more uniform and fine powder in Step 3.
- step 3a the solid residue obtained in step 2 is heat-treated to obtain a heat-treated product.
- the temperature during this heat treatment is 700 ° C. to 1400 ° C., preferably 800 ° C. to 1300 ° C.
- a temperature of 700 ° C. or higher is required.
- it exceeds 1400 degreeC it will become difficult to make content of carbon, nitrogen, and oxygen in a composite particle into the said range.
- Examples of the heat treatment method include a stationary method, a stirring method, a dropping method, and a powder trapping method.
- the rate of temperature rise is not particularly limited, but is preferably about 1 ° C./min to 100 ° C./min, more preferably 5 ° C./min to 50 ° C./min. is there.
- the heating time is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours, and further preferably 0.5 to 3 hours.
- the heating time is 0.1 to 10 hours, preferably 0.5 to 5 hours.
- the heating time of the solid residue is usually 0.1 to 5 hours, preferably 0.5 to 2 hours.
- the average residence time calculated from the steady sample flow rate in the furnace is set as the heating time.
- the heating time of the solid residue is usually 0.5 to 10 minutes, preferably 0.5 to 3 minutes.
- the heating time is within the above range, uniform heat-treated particles tend to be formed.
- the heating time of the solid residue is 0.2 seconds to 1 minute, preferably 0.2 to 10 seconds.
- the heating time is within the above range, uniform heat-treated particles tend to be formed.
- an infrared furnace such as an electric furnace using electricity as a heat source or an infrared gold image furnace capable of strict temperature control.
- the atmosphere during the heat treatment is preferably a non-oxidizing atmosphere so that the content of each constituent element of the composite particles can be easily within the above range.
- the main component is preferably a non-oxidizing gas atmosphere.
- non-oxidizing gases nitrogen, argon, helium, and hydrogen are preferable, nitrogen and argon are more preferable, and a mixed gas of these gases and hydrogen is more preferable because it is relatively inexpensive and easily available.
- These non-oxidizing gases may be used alone or in combination of two or more.
- the concentration of hydrogen gas is, for example, 100% by volume or less, preferably 1 to 20% by volume, more preferably 1 to 5% by volume.
- the heat-treated product obtained by the heat treatment may be used as it is in the next step, or may be used in the next step after further crushing.
- operations for making the heat-treated product fine such as crushing and crushing, are referred to as “crushing” without any particular distinction.
- crushing for example, a roll rolling mill, a ball mill, a small-diameter ball mill (bead mill), a medium stirring mill, an airflow grinder, a mortar, an automatic kneading mortar, a tank disintegrator, or a jet mill can be used.
- step 4a the heat-treated product obtained in step 3a is oxidized with an oxidizing agent that donates oxygen atoms so that the D / G ratio is in the range of 0.4 to 1.0.
- Examples of the oxidizing agent that donates oxygen atoms include hydrogen peroxide, perchloric acid, peracetic acid, and water.
- the water may be used as water vapor.
- the D / G ratio can be set within the above range by adjusting the degree of oxidation. Oxidation can reduce the D / G ratio, but excessive oxidation treatment increases the D / G ratio. What is necessary is just to obtain
- the degree of oxidation can be adjusted by appropriately selecting the type of oxidant, the amount of oxidant, the oxidation treatment temperature, the oxidation treatment time, and the like. In particular, the adjustment of the oxidation treatment temperature is important.
- step 4 is performed simultaneously with the start of the step 3 or after the start of the step 3 (hereinafter, step 3).
- the portion that overlaps with step 4 is also referred to as “step 3b”.
- the oxidant used in the overlapping step 4 ie, step 3b
- the second mode is a mode in which step 4 ends simultaneously with step 3.
- Step 1 of obtaining a catalyst precursor solution by mixing a titanium-containing compound (1), a nitrogen-containing organic compound (2) and a solvent Step 2 for removing a solvent from the catalyst precursor solution to obtain a solid residue, and heat treatment of the solid residue obtained in Step 2 at a temperature of 700 ° C. to 1400 ° C. while introducing water.
- Step 3b In which at least one of the titanium-containing compound (1) and the nitrogen-containing organic compound (2) has an oxygen atom.
- Step 1 and Step 2 in the second aspect are the same as Step 1 and Step 2 in the first aspect, respectively.
- step 3 in the second embodiment the portion before step 4 is started is the same as step 3a in the first embodiment.
- step 3b will be described.
- step 3b oxidation treatment is performed while the solid residue obtained in step 2 is heat-treated.
- the process 4 is repeated at the same time as the start of the process 3, and in the process 3b, the solid residue obtained in the process 2 is heat-treated at a temperature of 700 ° C. to 1400 ° C. while introducing water. obtain.
- a heat-treated product is produced, and at the same time, the heat-treated product is oxidized.
- an oxygen reduction catalyst having a D / G ratio of 0.4 to 1.0 is obtained.
- Preferred conditions for the heat treatment are the same as those mentioned in the step 3a of the first aspect.
- the heat treatment while introducing water is performed by mixing water in the gas atmosphere mentioned in the step 3a of the first aspect.
- the amount of water to be introduced is not particularly limited as long as the oxidation treatment proceeds, but it is preferably a saturated water vapor amount at 0 ° C. to 50 ° C. and contained in the introduced atmospheric gas for easy handling.
- a 3rd aspect is an aspect by which the said process 4 is performed after completion
- the step 4c similar to the step 4a is performed after the end of the step 3b in the second aspect.
- the step 3b is a step (hereinafter also referred to as “step 3c”) that does not necessarily require oxidation treatment so that the D / G ratio becomes 0.4 to 1.0.
- the oxidizing agent used in Step 4 (Step 4a) in the first embodiment and the portion (Step 4c) performed after Step 3 in Step 4 in the third embodiment is hydrogen peroxide, perchloric acid. And at least one selected from peracetic acid is preferred because it is easy to handle.
- Step 1 and Step 2 in the third aspect are the same as Step 1 and Step 2 in the first aspect, respectively.
- oxidation treatment is performed in step 3c so that the D / G ratio is 0.4 to 1.0, and further, oxidation treatment is performed in step 4c in order to adjust to a desired D / G ratio. May be.
- the composite particles may be loaded with a noble metal or a noble metal alloy (hereinafter also referred to as “noble metal etc.”) (hereinafter also referred to as “composite catalyst”).
- the method for supporting these noble metals and the like is not particularly limited as long as they can be supported for practical use, but a method for supporting noble metals or the like using a precursor such as a noble metal is preferable.
- a precursor such as a noble metal is a substance that can be converted into the noble metal by a predetermined treatment, and examples thereof include chloroplatinic acid, iridium chloride, palladium chloride, and a mixture thereof.
- the method of supporting the precursor such as noble metal on the composite particles is not particularly limited, and a method using a conventionally known catalyst metal supporting technology can be used.
- a method using a conventionally known catalyst metal supporting technology can be used.
- a method comprising a step of dispersing particles and adsorbing a precursor colloid such as a noble metal to the composite particles, thereby supporting the noble metal or the like on the composite particles; and (3) a solution containing one or more precursors such as noble metals and the like; Adjusting the pH of the mixed liquid with the composite particle dispersion to obtain a metal oxide, a hydrous oxide, and a metal hydroxide and simultaneously adsorbing them to the composite particles, reducing them, and And a method including a step of heat-treating it, and the like, but is not limited thereto.
- the oxygen reduction catalyst of the present invention is not particularly limited in use, but can be suitably used for a fuel cell electrode catalyst, an air cell electrode catalyst, and the like.
- the oxygen reduction catalyst of the present invention can be used as an alternative catalyst for a conventional platinum-supported carbon catalyst.
- a fuel cell catalyst layer can be produced from the oxygen reduction catalyst.
- the fuel cell catalyst layer includes an anode catalyst layer and a cathode catalyst layer, but the oxygen reduction catalyst is preferably used for the cathode catalyst layer because of its excellent durability and high oxygen reduction ability.
- the fuel cell catalyst layer includes the oxygen reduction catalyst and a polymer electrolyte.
- electron conductive particles may be further included in the catalyst layer.
- the material of the electron conductive particles examples include carbon, a conductive polymer, a conductive ceramic, a metal, or a conductive inorganic oxide such as tungsten oxide or iridium oxide, which can be used alone or in combination. .
- the electron conductive particles made of carbon have a large specific surface area, and are easily available with a small particle size at low cost and excellent in chemical resistance, carbon alone or carbon and other electron conductive particles can be used. Mixtures are preferred.
- Examples of carbon include carbon black, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, fullerene, porous carbon, and graphene. If the particle size of the electron conductive particles made of carbon is too small, it becomes difficult to form an electron conduction path. If the particle size is too large, the gas diffusibility of the fuel cell catalyst layer and the catalyst utilization rate tend to decrease. Therefore, the thickness is preferably 10 to 1000 nm, more preferably 10 to 100 nm.
- the mass ratio of the oxygen reduction catalyst to the electron conductive particles is preferably 1: 1 to 100: 1.
- the fuel cell electrode catalyst layer usually contains a polymer electrolyte.
- the polymer electrolyte is not particularly limited as long as it is generally used in a fuel cell catalyst layer.
- a perfluorocarbon polymer having a sulfonic acid group for example, NAFION (registered trademark)
- a hydrocarbon-based polymer compound having a sulfonic acid group for example, phosphoric acid
- a highly doped inorganic acid such as phosphoric acid.
- examples thereof include molecular compounds, organic / inorganic hybrid polymers partially substituted with proton conductive functional groups, and proton conductors in which a polymer matrix is impregnated with a phosphoric acid solution or a sulfuric acid solution.
- Nafion registered trademark
- NAFION registered trademark
- DE521, manufactured by DuPont a 5% Nafion (NAFION (registered trademark)) solution
- the method for forming the fuel cell catalyst layer is not particularly limited.
- the coating method include a dipping method, a screen printing method, a roll coating method, a spray method, and a bar coater coating method.
- a fuel cell catalyst is formed on the electrolyte membrane by a transfer method.
- the method of forming a layer is mentioned.
- the suspension is referred to as “ink for preparing a fuel cell catalyst layer”.
- the electrode includes the fuel cell catalyst layer and a gas diffusion layer.
- an electrode including the anode catalyst layer is referred to as an anode
- an electrode including the cathode catalyst layer is referred to as a cathode.
- the gas diffusion layer is a porous layer that assists gas diffusion.
- the gas diffusion layer may be anything as long as it has electron conductivity, high gas diffusibility, and high corrosion resistance.
- carbon-based porous materials such as carbon paper and carbon cloth are used. Materials and aluminum foil coated with stainless steel and corrosion-resistant materials for weight reduction are used.
- the membrane electrode assembly is composed of a cathode catalyst layer, an anode catalyst layer, and a polymer electrolyte membrane disposed between the catalyst layers.
- the membrane electrode assembly may have a gas diffusion layer.
- a conventionally known fuel cell catalyst layer for example, a fuel cell catalyst layer containing a platinum-supported carbon catalyst instead of the oxygen reduction catalyst can be used.
- the membrane electrode assembly may be referred to as “MEA”.
- polymer electrolyte membrane for example, a polymer electrolyte membrane using a perfluorosulfonic acid polymer or a polymer electrolyte membrane using a hydrocarbon polymer is generally used.
- a membrane impregnated with a liquid electrolyte or a membrane filled with a polymer electrolyte in a porous body may be used.
- the cathode catalyst layer and the anode catalyst layer are sandwiched between the two surfaces of the electrolyte membrane with the gas diffusion layer. You can get it.
- the membrane electrode assembly Since the membrane electrode assembly has high catalytic ability and high catalyst durability, it can be suitably used for fuel cell or air battery applications.
- Fuel cells are classified into several types depending on the electrolyte used, etc., and include molten carbonate type (MCFC), phosphoric acid type (PAFC), solid oxide type (SOFC), and solid polymer type (PEFC). .
- MCFC molten carbonate type
- PAFC phosphoric acid type
- SOFC solid oxide type
- PEFC solid polymer type
- the membrane electrode assembly is preferably used for a polymer electrolyte fuel cell, and hydrogen, methanol or the like can be used as a fuel.
- the fuel cell using the oxygen reduction catalyst has high performance, particularly good initial performance, and excellent start / stop durability. Further, the fuel cell using the oxygen reduction catalyst of the present invention has a feature that it is less expensive than the conventional fuel cell using the platinum-supported carbon catalyst.
- the fuel cell has at least one function selected from the group consisting of a power generation function, a light emission function, a heat generation function, a sound generation function, an exercise function, a display function, and a charging function, and improves the performance of an article including the fuel cell. Can do.
- Specific examples of articles provided with the fuel cell include buildings, houses, buildings such as tents, fluorescent lamps, LEDs, etc., organic EL, street lamps, indoor lighting, lighting fixtures such as traffic lights, machines, vehicles themselves Equipment including automobile equipment, home appliances, agricultural equipment, electronic equipment, mobile phones, etc., sanitary equipment such as beauty equipment, portable tools, bathroom accessories, furniture, toys, decorations, bulletin boards, coolers
- Examples include outdoor supplies such as boxes, outdoor generators, teaching materials, artificial flowers, objects, power supplies for cardiac pacemakers, and power supplies for heating and cooling devices equipped with Peltier elements.
- Nitrogen / oxygen About 0.1 g of a sample was weighed and sealed in Ni-Cup, and then measured with a TC600 manufactured by LECO.
- Transition metal elements titanium, etc.: About 0.1 g of a sample was weighed on a platinum dish, and acid was added for thermal decomposition. This heat-decomposed product was fixed, diluted appropriately, and quantified using ICP-OES (VISA-PRO from SII) or ICP-MS (HP7500 from Agilent). 2. Powder X-ray diffraction measurement The powder X-ray diffraction of the sample was measured using X'Pert MPD manufactured by PANalytical. Cu-K ⁇ was used as the X-ray light source.
- the diffraction line peak in powder X-ray diffraction of each sample was counted by regarding a signal that can be detected with a ratio (S / N) of signal (S) to noise (N) of 2 or more as one peak.
- the noise (N) is the width of the baseline. 3.
- Raman Spectroscopic Measurement Microscopic Raman measurement was performed with NRS-5100 manufactured by JASCO. Prior to sample measurement, the apparatus was calibrated using a reference silicon substrate. Sample measurement was performed in a lattice measurement mode, with nine measurements taken once, and a total of 5 measurements (total 45 locations) at different sample positions. The spectra obtained from each measurement were averaged to obtain the final result.
- the excitation wavelength was 532 nm, and the exposure time and integration number were 3 seconds and 5 times for each laser irradiation point.
- the obtained spectrum was analyzed using Spectra Manager Version 2 manufactured by JASCO. That is, after appropriate baseline correction, the 850 ⁇ 2000 cm -1 region of the spectrum, peak fitting with 1340cm -1, 1365cm -1, 1580cm -1 , 4 single Lorentz function with maximum at 1610 cm -1 did. And the resulting peak of 1340 cm -1 (D band), the intensity ratio of the peak of 1580 cm -1 (G band) was calculated as the D / G ratio. 4). BET specific surface area measurement 0.15 g of a sample was sampled, and the specific surface area was measured with a fully automatic BET specific surface area measuring device Macsorb (manufactured by Mountech).
- the pretreatment time and pretreatment temperature were set to 30 minutes and 200 ° C., respectively. 5.
- Transmission Electron Microscope Observation Transmission electron microscope (TEM) observation was performed using H9500 (acceleration voltage 300 kV) manufactured by Hitachi, Ltd. The observation sample was prepared by dropping a dispersion obtained by ultrasonically dispersing a sample powder in ethanol onto a TEM observation microgrid. In addition, energy dispersive X-ray fluorescence analysis was performed using Hitachi HD2300 (acceleration voltage 200 kV). [Example 1] 1-1.
- This powder was placed in a tube furnace, heated to 900 ° C. at a heating rate of 10 ° C./min in a mixed gas atmosphere of hydrogen and nitrogen containing 4% by volume of hydrogen, and heat-treated at 900 ° C. for 1 hour.
- a carbonitride oxide powder was obtained.
- This powder was subjected to a planetary ball mill treatment in isopropanol (manufactured by Junsei Kagaku), followed by filtration and drying to obtain a powder.
- Hydrogen peroxide treatment 1.6 g of the above powder was added to a mixed solution of 800 mL of distilled water and 800 mL of 30% hydrogen peroxide solution (manufactured by Kanto Chemical), and reacted at 25 ° C.
- catalyst (1) a powder (hereinafter also referred to as “catalyst (1)”).
- catalyst (1) a powder
- platinum loading operation In 1250 ml of distilled water, 1.00 g of catalyst (1) and 363 mg of sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) were shaken for 30 minutes with an ultrasonic cleaner. This suspension was stirred in a water bath at a liquid temperature of 80 ° C. for 30 minutes.
- composite catalyst (1) A 20 mass% platinum-containing composite catalyst (hereinafter also referred to as “composite catalyst (1)”) was obtained.
- catalyst (2) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction time for hydrogen peroxide treatment was 30 minutes. Further, a 20% by mass platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (2)”) is also used in the same manner as in Example 1-3 above except that the catalyst (2) is used instead of the catalyst (1). )
- catalyst (3) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction time for hydrogen peroxide treatment was 8 hours. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (3)”) is also used in the same manner as in Example 1-3 above except that the catalyst (3) is used instead of the catalyst (1). )
- catalyst (3) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction temperature of the hydrogen peroxide treatment was 0 ° C. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (4)”) is also used in the same manner as in Example 1-3 above, except that the catalyst (4) is used instead of the catalyst (1). )
- This powder was put into a tubular furnace, passed through a bubbler containing distilled water kept at 25 ° C., saturated with water vapor, and mixed with hydrogen and nitrogen containing 4% by volume of hydrogen and nitrogen. The temperature was raised to 880 ° C. at a rate of ° C./min, and the powder was heat treated at 880 ° C. for 1 hour to obtain titanium and iron-containing carbonitride oxide powder.
- This powder was treated with a planetary ball mill in isopropanol (manufactured by Junsei Chemical Co., Ltd.), then filtered and dried to obtain a powder (hereinafter also referred to as “catalyst (5)”). 5-2.
- Platinum loading operation Except that the catalyst (5) is used instead of the catalyst (1), a 20 mass% platinum-containing composite catalyst (hereinafter also referred to as “composite catalyst (5)”) is obtained in the same manner as in Example 1-3 above. .)
- catalyst (6) was prepared in the same manner as in Example 5-1, except that ammonium ferrocyanide (manufactured by Wako Pure Chemical Industries) was used instead of iron (II) acetate. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (6)”) is also used in the same manner as in Example 1-3 above except that the catalyst (6) is used instead of the catalyst (1). )
- catalyst (6) and composite catalyst (6) were prepared.
- the catalyst (6) was treated with hydrogen peroxide to obtain a catalyst (7).
- composite catalyst (7) a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (7)”) is also used in the same manner as in Example 1-3 above except that catalyst (7) is used instead of catalyst (1). )
- Example 8 Each evaluation mentioned later was performed using catalyst (7) and composite catalyst (7).
- a catalyst (7) was prepared.
- 1.00 g of catalyst (7) and 21 mL of a 1.0 mol / L sodium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) were added to 1250 ml of distilled water, and the mixture was shaken for 30 minutes with an ultrasonic cleaner. This suspension was stirred in a water bath at a liquid temperature of 80 ° C. for 30 minutes.
- composite catalyst (8) platinum-cobalt-containing composite catalyst containing 20% by mass of platinum and alloyed with platinum in a molar ratio of 1: 1 was obtained.
- Example 9 Each evaluation mentioned later was performed using catalyst (7) and composite catalyst (8).
- a catalyst (7) was prepared.
- 1.00 g of catalyst (7) and 21 mL of a 1.0 mol / L sodium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) were added to 1250 ml of distilled water, and the mixture was shaken for 30 minutes with an ultrasonic cleaner. This suspension was stirred in a water bath at a liquid temperature of 80 ° C. for 30 minutes.
- composite catalyst (9) containing 20% by mass of platinum and alloying platinum and nickel at a molar ratio of 1: 1 was obtained.
- glycine manufactured by Wako Pure Chemical Industries, Ltd.
- a glycine-containing mixture solution was prepared by stirring at room temperature and completely dissolving.
- the titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution.
- the temperature of the water bath was set to about 80 ° C., and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution.
- the solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.
- This powder was put in a tubular furnace, and the temperature in the furnace was increased to 900 ° C. at a temperature increase rate of 10 ° C./min in a mixed gas atmosphere of hydrogen and nitrogen containing 4% by volume of hydrogen, and the powder was heated at 900 ° C. for 1 hour.
- titanium-containing oxycarbonitride powder was obtained.
- This powder was treated with a planetary ball mill in isopropanol (Pure Chemical), then filtered and dried to obtain a powder (hereinafter also referred to as “catalyst (8)”).
- Platinum loading operation 20% by mass platinum-containing composite catalyst hereinafter also referred to as “composite catalyst (10)” in the same manner as in Example 1-3 above except that catalyst (8) is used instead of catalyst (1). .)
- the titanium-containing mixture solution was slowly added to the glycine-containing mixture solution to obtain a transparent catalyst precursor solution.
- the temperature of the water bath was set to about 80 ° C., and the solvent was slowly evaporated while heating and stirring the catalyst precursor solution.
- the solid residue obtained by completely evaporating the solvent was finely and uniformly crushed in a mortar to obtain a powder.
- This powder was put into a tube furnace, and the temperature in the furnace was increased to 900 ° C. at a temperature increase rate of 10 ° C./min in a mixed gas atmosphere of hydrogen and nitrogen containing 4% by volume of hydrogen, and the powder was heat-treated at 900 ° C. for 1 hour. By doing this, titanium and iron-containing carbonitride oxide powder was obtained.
- This powder was subjected to a planetary ball mill treatment in isopropanol (manufactured by Junsei Kagaku), and then filtered and dried to obtain a powder (hereinafter also referred to as “catalyst (9)”).
- Platinum loading operation 20% by mass platinum-containing composite catalyst hereinafter also referred to as “composite catalyst (11)” in the same manner as in Example 1-3 above, except that catalyst (9) is used instead of catalyst (1). .
- catalyst (10) was prepared in the same manner as Comparative Example 2-1, except that the tubular furnace used for heat treatment was an infrared gold image furnace manufactured by ULVAC-RIKO, and the heat treatment temperature was changed to 1100 ° C. instead of 900 ° C. did. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (12)” is also described in the same manner as in Example 1-3 above except that the catalyst (10) is used instead of the catalyst (1). )
- catalyst (11) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction temperature of the hydrogen peroxide treatment was 40 ° C. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (13)”) is also used in the same manner as in Example 1-3 above except that the catalyst (11) is used instead of the catalyst (1). )
- a catalyst (12) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction temperature of the hydrogen peroxide treatment was changed to 60 ° C. Further, a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (14)”) is also used in the same manner as in Example 1-3 above except that the catalyst (12) is used instead of the catalyst (1). )
- a catalyst (13) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that the reaction temperature of the hydrogen peroxide treatment was 100 ° C.
- a 20 mass% platinum-containing composite catalyst hereinafter referred to as “composite catalyst (15)” is also used in the same manner as in Example 1-3 above except that the catalyst (13) is used instead of the catalyst (1).
- the above titanium carbonitride powder is heated at 1000 ° C. for 10 hours in a tubular furnace while flowing a hydrogen and nitrogen mixed gas containing 1 vol% oxygen gas and 4 vol% hydrogen.
- Carbonitride oxide hereinafter also referred to as “catalyst (14)” was obtained. 7-2. Platinum loading operation Except that the catalyst (14) is used instead of the catalyst (1), a 20 mass% platinum-containing composite catalyst (hereinafter also referred to as “composite catalyst (16)”) is obtained in the same manner as in Example 1-3 above. .)
- a contained composite catalyst hereinafter also referred to as “composite catalyst (17)”. was obtained.
- catalyst (16) and composite catalyst (18) 20% by mass platinum-containing composite catalyst in the same manner as in Example 1-3 above, except that titanium nitride (manufactured by Soekawa Rikagaku Co., Ltd., hereinafter also referred to as “catalyst (17)”) is used instead of catalyst (1). (Hereinafter also referred to as “composite catalyst (19)”).
- catalyst (17) and composite catalyst (19) were evaluated using catalyst (17) and composite catalyst (19).
- a contained composite catalyst hereinafter also referred to as “composite catalyst (20)”. was obtained.
- Water was supplied at 0.1 g / h to a heating tube set at 120 ° C., and nitrogen gas was further supplied at 100 mL / min to obtain a mixed gas (2) of water vapor and nitrogen gas.
- the reactor (1) was heated from the outside to 1200 ° C. to react with titanium tetrachloride gas, ammonia gas, methane gas, and water vapor.
- catalyst (20) a 20 mass% platinum-containing catalyst (hereinafter referred to as “1-3) of Example 1 was used. (Also referred to as “composite catalyst (22)”).
- the contents of cobalt, carbon, nitrogen and oxygen were 0.83, 95, 0.5 and 0.90% by mass, respectively.
- the obtained catalyst (20) had a D / G ratio of 0.63 and a BET specific surface area of 178 m 2 / g.
- composite catalyst (23) a 20% by mass platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (23)” is also described in the same manner as in Example 1-3 above except that the catalyst (21) is used instead of the catalyst (1). )
- the obtained catalyst (21) had a D / G ratio of 1.13 and a BET specific surface area of 286 m 2 / g.
- a catalyst (22) was prepared in the same manner as in Examples 1-1 and 1-2 in Example 1 except that titanium tetraisopropoxide was not added.
- composite catalyst (24) a 20 mass% platinum-containing composite catalyst (hereinafter referred to as “composite catalyst (24)”) is also used in the same manner as in Example 1-3 above except that the catalyst (22) is used instead of the catalyst (1). )
- the obtained catalyst (22) had a D / G ratio of 1.03 and a BET specific surface area of 287 m 2 / g.
- FIG. 3 shows a powder X-ray diffraction (XRD) pattern of the catalyst (1) using Cu-K ⁇ as an X-ray light source. From the comparison with the XRD pattern of a standard sample, rutile TiO 2 (manufactured by Wako Pure Chemical Industries, Ltd.) measured as a reference system, the main phase of the catalyst (1) was identified as rutile titanium oxide.
- XRD powder X-ray diffraction
- the catalyst (1) and the rutile TiO 2 satisfy the following conditions. That is, regions A to D occupying the 2 ⁇ range described below: A: 26-28 ° B: 35-37 ° C: 40-42 ° D: 53-55 °
- the peak having the maximum intensity is present in the region A among all the peaks appearing in the diffraction pattern.
- the XRD patterns of catalyst (2) to catalyst (7) the same diffraction peak group as in catalyst (1) satisfying the above conditions was observed, and the main phase was identified as titanium oxide having a rutile structure.
- X-ray absorption spectroscopy X-ray absorption spectroscopy (XAS) measurement of catalyst (1) to catalyst (7) was performed at the large synchrotron radiation facility SPring-8.
- the threshold value of X-ray absorption is a standard sample measured as a reference system, TiO 2 (titanium valence 4), and Ti 2 O 3 (titanium). The value was between 3). From this, the valence of titanium contained in the catalyst (1) to the catalyst (7) was estimated to be larger than 3.0 and less than 4.0.
- the ratio of the number of atoms of carbon, nitrogen, oxygen, and M2 to titanium contained in the catalyst (1) to the catalyst (7) according to each of the above examples is within the preferable range described above.
- the D / G ratio of the catalyst (1) to the catalyst (7) according to each of the above examples is in the range of 0.4 to 1.0 in any case.
- the specific surface areas calculated by the BET method of the catalysts (1) to (7) according to the above examples are all in the range of 150 to 600 m 2 / g.
- [Manufacture of membrane electrode assemblies for fuel cells and evaluation of their power generation characteristics] 1. Preparation of cathode ink 33.7 mg of the composite catalyst (1) prepared in Example 1 above and 8.43 mg of graphitized carbon black (GrCB-K, manufactured by Showa Denko) as an electron conductive material were mixed, and protons were further mixed.
- GrCB-K graphitized carbon black
- Conductive material (0.56 g of an aqueous solution containing 25.3 mg of NAFION (registered trademark) (5% aqueous solution of NAFION (registered trademark), manufactured by Wako Pure Chemical Industries, Ltd.)), 2.3 mL of pure water, isopropanol (
- the ink for cathode (1) was prepared by adding 2.3 mL of Junsei Chemical Co., Ltd. and irradiating with ultrasonic washing in ice water for 30 minutes.
- cathode ink (9) and cathode ink (22) were prepared in the same manner as described above. Further, a cathode ink (23) was prepared using the composite catalyst (7) in the same manner as described above.
- cathode electrode having catalyst layer for fuel cell A gas diffusion layer (carbon paper (TGP-H-060, manufactured by Toray)) was degreased by being immersed in acetone (manufactured by Wako Pure Chemical Industries) for 30 seconds, and then dried. Subsequently, it was immersed in a 10% polytetrafluoroethylene (PTFE) aqueous solution for 30 seconds.
- acetone manufactured by Wako Pure Chemical Industries
- the soaked product was dried at room temperature and heated at 350 ° C. for 1 hour to obtain a gas diffusion layer (hereinafter also referred to as “GDL”) having PTFE dispersed in the carbon paper and having water repellency.
- GDL gas diffusion layer
- cathode (1) was applied to the surface of the GDL having a size of 5 cm ⁇ 5 cm by an automatic spray coating apparatus (manufactured by Saneitec Co., Ltd.) at 80 ° C., and the catalyst (1) and graphitization were performed.
- An electrode hereinafter also referred to as “cathode (1)” having a cathode catalyst layer with a total amount of carbon black of 0.625 mg / cm 2 per unit area on the GDL surface was produced.
- cathode (21) To cathode (21) were prepared.
- the cathode ink (8) was applied to the surface of the GDL having a size of 5 cm ⁇ 5 cm by an automatic spray coating apparatus (manufactured by Saneitec Co., Ltd.) at 80 ° C., and the total amount of the catalyst (8) was unit.
- An electrode hereinafter also referred to as “cathode (8)” having a cathode catalyst layer of 0.500 mg / cm 2 per area on the GDL surface was produced.
- the cathode ink (9), the cathode ink (22), and the cathode ink (23), the cathode (9), the cathode (22), and the cathode (23) were prepared in the same manner as described above.
- the cathode ink (Pt / C) was applied to the surface of the GDL having a size of 5 cm ⁇ 5 cm by an automatic spray coating apparatus (manufactured by Saneitec Co., Ltd.) at 80 ° C., and the total amount of the Pt / C An electrode (hereinafter also referred to as “cathode (Pt / C)”) having a cathode catalyst layer with a surface area of 0.200 mg / cm 2 on the GDL surface was prepared.
- the amount of noble metal per unit area in each of the cathodes was 0.1 mg / cm 2 . 3.
- the soaked product was dried at room temperature and heated at 350 ° C. for 1 hour to obtain a gas diffusion layer (hereinafter also referred to as “GDL”) having PTFE dispersed in the carbon paper and having water repellency.
- GDL gas diffusion layer
- anode ink (1) was applied to the surface of the GDL having a size of 5 cm ⁇ 5 cm by an automatic spray coating apparatus (manufactured by Sanei Tech Co., Ltd.) at 80 ° C., and the total amount of the platinum-supported carbon catalyst was An electrode having an anode catalyst layer of 1.00 mg / cm 2 per unit area on the GDL surface (hereinafter also referred to as “anode (1)”) was produced. 5.
- membrane electrode assembly for fuel cell A NAFION (registered trademark) membrane (NR-212, manufactured by DuPont) is prepared as an electrolyte membrane, the cathode (1) as a cathode, and an anode (1) as an anode. did.
- a fuel cell membrane electrode assembly (hereinafter also referred to as “MEA”) in which the electrolyte membrane is disposed between the cathode and the anode was produced as follows.
- the electrolyte membrane is sandwiched between the cathode (1) and the anode (1), and a temperature of 140 is used using a hot press machine so that the cathode catalyst layer (1) and the anode catalyst layer (1) are in close contact with the electrolyte membrane. These were thermocompression bonded at 7 ° C. under a pressure of 1 MPa to produce MEA (1).
- MEA (2) to MEA (23) and MEA (Pt / C) were produced in the same manner as described above. 6).
- Production of single cell The MEA (1) produced in 5 above is fixed with bolts by sandwiching it between two sealing materials (gaskets), two separators with gas flow paths, two current collector plates and two rubber heaters. Was tightened to a predetermined surface pressure (4N) to produce a single cell of a polymer electrolyte fuel cell (hereinafter also referred to as “single cell (1)”) (cell area: 5 cm 2 ).
- a single cell (24) was produced in the same manner as the single cell (1) except that the composite catalyst (23) was used instead of the composite catalyst (1).
- a single cell (25) was produced in the same manner as the single cell (1) except that the composite catalyst (24) was used instead of the composite catalyst (1). 7).
- Start / stop durability test The temperature of the single cell (1) was adjusted to 80 ° C, the anode humidifier to 80 ° C, and the cathode humidifier to 80 ° C. Thereafter, hydrogen was supplied as fuel to the anode side and air was supplied to the cathode side, and the current-voltage (IV) characteristics of the single cell (1) were evaluated.
- the voltage value at a certain current density is an indicator of the performance of the fuel cell. That is, the higher the initial voltage, the higher the initial performance of the fuel cell, and the higher the activity of the oxygen reduction catalyst. Further, the higher the voltage holding ratio, the higher the start / stop durability of the fuel cell, and hence the oxygen reduction catalyst.
- the initial voltage at 0.3 A / cm 2 was 0.5 V or more, and good initial performance was exhibited.
- the single cell (7) according to Example 7 showed higher initial performance than the single cell (Pt / C) using Pt / C according to Comparative Example 13.
- the voltage holding ratio at 0.3 A / cm 2 after applying the triangular wave potential cycle 20000 times is 60%. As described above, good start / stop durability was exhibited. It should be noted that all of these exhibited a higher voltage holding ratio than the single cell (Pt / C) using Pt / C according to Comparative Example 13, and in particular, the single cells according to Examples 7 to 9 described above.
- the cells (7) to (9) and the single cell (23) showed an extremely high voltage holding ratio of 80% or more.
- the oxygen reduction catalyst prepared in each of the above examples has good initial performance and excellent start-stop durability.
- Reactor (1) 2 Mixed gas with titanium tetrachloride gas and nitrogen gas (1) 3: Mixed gas with methane, ammonia, water and nitrogen (4) 4: Reactant (to collection) 5: Primary particles of titanium compound 6: Graphite-like carbon 7: Amorphous-like carbon
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Abstract
Description
チタン化合物の一次粒子がカーボンの構造体中に分散した複合粒子を含む酸素還元触媒であって、
前記複合粒子が、チタン、炭素、窒素、および酸素を構成元素として有し、前記各元素の原子数の比が、チタンを1とした場合に、炭素の比が2より大きく5以下、窒素の比が0より大きく1以下、酸素の比が1以上3以下であり、
かつラマンスペクトルにおけるDバンドのピーク強度の、Gバンドのピーク強度に対する強度比(D/G比)が0.4~1.0であることを特徴とする酸素還元触媒。
複合粒子が、鉄、ニッケル、クロム、コバルトおよびマンガンから選ばれる少なくとも1種の元素M2をさらに含み、かつ元素M2の総量のチタンに対する原子数の比が0.3以下である前記[1]に記載の酸素還元触媒。
複合粒子が、Cu‐Kα 線を用いたX線回折(XRD)測定において、下記記載の2θ 範囲を占める領域A~D:
A:26~28°
B:35~37°
C:40~42°
D:53~55°
のそれぞれにピークを持ち、かつ回折パターンに現れる全てのピークの中で最大の強度を持つピークを領域Aに有する前記[1]または[2]に記載の酸素還元触媒。
複合粒子の、透過法X線吸収微細構造解析(透過法XAFS)から求めたチタンの価数が3より大きく、4未満である前記[1]~[3]のいずれかに記載の酸素還元触媒。
さらに前記複合粒子に担持された貴金属または貴金属の合金からなる粒子を有する前記[1]~[4]のいずれかに記載の酸素還元触媒。
貴金属が、白金、パラジウム、イリジウム、ロジウムおよびルテニウムから選ばれる少なくとも1種の貴金属である前記[5]に記載の酸素還元触媒。
貴金属の合金が、貴金属と、鉄、ニッケル、クロム、コバルト、チタン、銅、バナジウムおよびマンガンから選ばれる少なくとも1種の金属とからなる合金である前記[5]または[6]に記載の酸素還元触媒。
前記[1]~[7]のいずれかに記載の酸素還元触媒を含むことを特徴とする燃料電池用触媒層作製用インク。
前記[8]に記載の燃料電池用触媒層作製用インクを用いて作製されることを特徴とする燃料電池用触媒層。
前記[9]に記載の燃料電池用触媒層を備えることを特徴とする燃料電池用電極。
カソードとアノードと該カソードおよび該アノードの間に配置された高分子電解質膜とで構成される膜電極接合体であって、前記カソード触媒層および/または前記アノード触媒層が、前記[9]に記載の燃料電池用電極層であることを特徴とする膜電極接合体。
前記[11]に記載の膜電極接合体を備えることを特徴とする燃料電池。
前記[1]~[7]のいずれかに記載の酸素還元触媒の製造方法であって、
チタン含有化合物(1)、窒素含有有機化合物(2)および溶媒を混合して触媒前駆体溶液を得る工程1、
前記触媒前駆体溶液から溶媒を除去して固形分残渣を得る工程2、
工程2で得られた固形分残渣を700℃~1400℃の温度で熱処理して熱処理物を得る工程3、および
工程3で得られる熱処理物を、酸素原子を供与する酸化剤で酸化処理を行う工程4
を含み、前記チタン含有化合物(1)および前記窒素含有有機化合物(2)のうち少なくとも1つが酸素原子を有し、工程4の酸化がD/G比が0.4~1.0の範囲になるように調整されることを特徴とする酸素還元触媒の製造方法。
酸素原子を供与する酸化剤が、水、過酸化水素、過塩素酸および過酢酸から選ばれる少なくとも1種である前記[13]に記載の酸素還元触媒の製造方法。
工程3の開始と同時または開始後に、工程4が工程3と重複して行われる前記[13]に記載の酸素還元触媒の製造方法。
工程3と重複した工程4で使用される酸化剤が水である前記[15]に記載の酸素還元触媒の製造方法。
工程3の終了後も工程4が行われる前記[15]または[16]に記載の酸素還元触媒の製造方法。
工程4のうち工程3の終了後に行われる部分において用いられる酸化剤が過酸化水素、過塩素酸および過酢酸から選ばれる少なくとも1種である前記[17]に記載の酸素還元触媒の製造方法。
本発明に係る酸素還元触媒は、チタン化合物の一次粒子がカーボンの構造体中に分散した複合粒子を含む酸素還元触媒であって、
チタン、炭素、窒素、および酸素を構成元素として有し、前記各元素の原子数の比が、チタンを1とした場合に、炭素が2より大きく5以下、窒素が0より大きく1以下、酸素が1以上3以下であり、
かつラマンスペクトルにおけるDバンドのピーク強度の、Gバンドのピーク強度に対する強度比(D/G比)が0.4~1.0である。
A:26~28°
B:35~37°
C:40~42°
D:53~55°
のそれぞれにピークを持ち、かつ回折パターンに現れる全てのピークの中で最大の強度を持つピークを領域Aに有することが好ましい。このような条件を満たす触媒は、ルチル型酸化チタンを主相として有すると考えられる。本発明の酸素還元触媒がこのような条件を満たすと、初期性能および起動停止耐久性がより良好になる。
<酸素還元触媒の製造方法>
本発明の酸素還元触媒の製造方法は、前記酸素還元触媒の製造方法であって、
チタン含有化合物(1)、窒素含有有機化合物(2)および溶媒を混合して触媒前駆体溶液を得る工程1、
前記触媒前駆体溶液から溶媒を除去して固形分残渣を得る工程2、
前記固形分残渣に対し熱処理を施す工程3および酸化処理を施す工程4
を含み、前記チタン含有化合物(1)および前記窒素含有有機化合物(2)のうち少なくとも1つが酸素原子を有する酸素還元触媒の製造方法である。
[第1の態様]
本発明の製造方法は、
チタン含有化合物(1)、窒素含有有機化合物(2)および溶媒を混合して触媒前駆体溶液を得る工程1、
前記触媒前駆体溶液から溶媒を除去して固形分残渣を得る工程2、
工程2で得られた固形分残渣を700℃~1400℃の温度で熱処理して熱処理物を得る工程3a、および
工程3aで得られる熱処理物を、酸素原子を供与する酸化剤で酸化処理を行う工程4aを含み、前記チタン含有化合物(1)および前記窒素含有有機化合物(2)のうち少なくとも1つが酸素原子を有し、工程4の酸化はD/G比が0.4~1.0の範囲になるように調整されることを特徴とする酸素還元触媒の製造方法である。
工程1では、少なくともチタン含有化合物(1)、窒素含有有機化合物(2)および溶媒を混合して触媒前駆体溶液を得る。第二の金属元素M2を含む複合粒子を調製する場合には、さらに第2の金属元素M2を含有する化合物として、鉄、ニッケル、クロム、コバルトおよびマンガンから選ばれる少なくとも1種の金属元素M2を含有する化合物(以下、「M2含有化合物(3)」ともいう。)を前記触媒前駆体溶液に添加すればよい。これらの材料を添加する順序は、特に限定されない。
チタン含有化合物(1)
チタン含有化合物(1)は、好ましくは、酸素原子およびハロゲン原子から選ばれる少なくとも1種を有しており、その具体例としては、チタン錯体、並びに、チタンのリン酸塩、硫酸塩、硝酸塩、有機酸塩、酸ハロゲン化物(ハロゲン化物の中途加水分解物)、アルコキシド、エステル、ハロゲン化物、過ハロゲン酸塩および次亜ハロゲン酸塩が挙げられ、より好ましくはチタンのアルコキシド、エステル、アセチルアセトン錯体、塩化物、臭化物、ヨウ化物、酸塩化物、酸臭化物、酸ヨウ化物および硫酸塩から選ばれる少なくとも一種が挙げられ、さらに好ましくは、前記液相中の溶媒への溶解性の観点から、アルコキシドまたはアセチルアセトン錯体が挙げられる。これらは、1種単独で用いてもよく2種以上を併用してもよい。
チタンテトラメトキシド、チタンテトラエトキシド、チタンテトラプロポキシド、チタンテトライソプロポキシド、チタンテトラブトキシド、チタンテトライソブトキシド、チタンテトラペントキシド、チタンテトラアセチルアセトナート、チタンオキシジアセチルアセトナート、トリス(アセチルアセトナト)第二チタン塩化物([Ti(acac)3]2[TiCl6])、四塩化チタン、三塩化チタン、オキシ塩化チタン、四臭化チタン、三臭化チタン、オキシ臭化チタン、四ヨウ化チタン、三ヨウ化チタン、オキシヨウ化チタン等のチタン化合物が挙げられる。これらは、1種単独で用いてもよく2種以上を併用してもよい。
塩化鉄(II)、塩化鉄(III)、硫酸鉄(III)、硫化鉄(II)、硫化鉄(III)、フェロシアン化カリウム、フェリシアン化カリウム、フェロシアン化アンモニウム、フェリシアン化アンモニウム、フェロシアン化鉄、硝酸鉄(II)、硝酸鉄(III)、シュウ酸鉄(II)、シュウ酸鉄(III)、リン酸鉄(II)、リン酸鉄(III)フェロセン、水酸化鉄(II)、水酸化鉄(III)、酸化鉄(II)、酸化鉄(III)、四酸化三鉄、エチレンジアミン四酢酸鉄(II)アンモニウム、酢酸鉄(II)、乳酸鉄(II)、クエン酸鉄(III)等の鉄化合物;
塩化ニッケル(II)、硫酸ニッケル(II)、硫化ニッケル(II)、硝酸ニッケル(II)、シュウ酸ニッケル(II)、リン酸ニッケル(II)、ニッケルセン、水酸化ニッケル(II)、酸化ニッケル(II)、酢酸ニッケル(II)、乳酸ニッケル(II)等のニッケル化合物;
塩化クロム(II)、塩化クロム(III)、硫酸クロム(III)、硫化クロム(III)、硝酸クロム(III)、シュウ酸クロム(III)、リン酸クロム(III)、水酸化クロム(III)、酸化クロム(II)、酸化クロム(III)、酸化クロム(IV)、酸化クロム(VI)、酢酸クロム(II)、酢酸クロム(III)、乳酸クロム(III)等のクロム化合物;
塩化コバルト(II)、塩化コバルト(III)、硫酸コバルト(II)、硫化コバルト(II)、硝酸コバルト(II)、硝酸コバルト(III)、シュウ酸コバルト(II)、リン酸コバルト(II)、コバルトセン、水酸化コバルト(II)、酸化コバルト(II)、酸化コバルト(III)、四酸化三コバルト、酢酸コバルト(II)、乳酸コバルト(II)等のコバルト化合物;
塩化マンガン(II)、硫酸マンガン(II)、硫化マンガン(II)、硝酸マンガン(II)、シュウ酸マンガン(II)、水酸化マンガン(II)、酸化マンガン(II)、酸化マンガン(III)、酢酸マンガン(II)、乳酸マンガン(II)、クエン酸マンガン等のマンガン化合物
が挙げられる。これらは、1種単独で用いてもよく2種以上を併用してもよい。
本発明の製造方法で用いられる窒素含有有機化合物(2)としては、チタン含有化合物(1)中のチタン原子に配位可能な配位子となり得る化合物が好ましく、多座配位子(好ましくは、2座配位子または3座配位子)となり得る(キレートを形成し得る)化合物がさらに好ましい。
溶媒
前記溶媒としては、たとえば水、酢酸、アセチルアセトン、アルコール類およびこれらの混合溶媒が挙げられる。アルコール類としては、エタノール、メタノール、ブタノール、プロパノールおよびエトキシエタノールが好ましく、エタノールおよびメタノールがさらに好ましい。溶解性を増すために、前記溶媒に酸を含有させることが好ましく、酸としては、酢酸、硝酸、塩酸、リン酸およびクエン酸が好ましく、酢酸および硝酸がさらに好ましい。これらは、1種単独で用いてもよく2種以上を併用してもよい。
工程2では、工程1で得られた触媒前駆体溶液から溶媒を除去して固形分残渣を得る。溶媒を除去する方法については特に限定されないが、例えば、スプレードライヤーやロータリーエバポレーターなどを用いる方法が挙げられる。
工程3aでは、前記工程2で得られた固形分残渣を熱処理して熱処理物を得る。
工程4aでは、工程3aで得られる熱処理物を、酸素原子を供与する酸化剤でD/G比が0.4~1.0の範囲になるように酸化処理を行う。
[第2の態様]
第2の態様は、前記第1の態様の工程1および2を行った後、前記工程3の開始と同時または開始後に、前記工程4が前記工程3と重複して行われ(以下、工程3のうち工程4と重複して行われる部分を「工程3b」とも記す。)、好ましくは、重複した前記工程4(すなわち工程3b)で使用される酸化剤が水である態様である。第2の態様は、工程4が工程3と同時に終了する態様である。
前記触媒前駆体溶液から溶媒を除去して固形分残渣を得る工程2、および
工程2で得られた固形分残渣を700℃~1400℃の温度で、水を導入しながら熱処理して熱処理物を得る工程3b、
を含み、前記チタン含有化合物(1)および前記窒素含有有機化合物(2)のうち少なくとも1つが酸素原子を有する酸素還元触媒の製造方法である。
工程3bでは、工程2で得られる固形分残渣を熱処理しながら、酸化処理を行う。好ましくは、工程3の開始と同時に工程4を重複して行い、工程3bでは、工程2で得られる固形分残渣を700℃~1400℃の温度で、水を導入しながら熱処理して熱処理物を得る。この処理により熱処理物が製造されると同時に、熱処理物が酸化処理される。その結果、D/G比が0.4~1.0である酸素還元触媒が得られる。
[第3の態様]
第3の態様は、第2の態様において工程3bの終了後も前記工程4が行われる態様である。
[貴金属または貴金属の合金の担持]
前記複合粒子に、貴金属または貴金属の合金(以下「貴金属等」とも記す。)を担持させてもよい(以下「複合触媒」とも記す。)。
本発明の酸素還元触媒は、特に用途に限りがあるわけではないが、燃料電池用電極触媒、空気電池用電極触媒などに好適に用いることができる。
前記酸素還元触媒から燃料電池用触媒層を製造することができる。
電極は前記燃料電池用触媒層とガス拡散層とから構成される。以下、アノード触媒層を含む電極をアノードと、カソード触媒層を含む電極をカソードと呼ぶ。
膜電極接合体は、カソード触媒層とアノード触媒層と前記両触媒層の間に配置された高分子電解質膜で構成される。また、前記膜電極接合体は、ガス拡散層を有していてもよい。このとき、アノード触媒層として、従来公知の燃料電池用触媒層、例えば、前記酸素還元触媒の代わりに白金担持カーボン触媒を含む燃料電池用触媒層を用いることができる。
前記膜電極接合体は、触媒能および触媒耐久性が高いことから、燃料電池または空気電池の用途に好適に用いることができる。
前記酸素還元触媒を用いた燃料電池は性能が高く、特に良好な初期性能を有し、かつ起動停止耐久性に優れるという特徴を持つ。また、本発明の酸素還元触媒を用いた燃料電池は、従来の白金担持カーボン触媒を用いた燃料電池よりも安価であるという特徴を持つ。この燃料電池は、発電機能、発光機能、発熱機能、音響発生機能、運動機能、表示機能および充電機能からなる群より選ばれる少なくとも一つの機能を有し燃料電池を備える物品の性能を向上させることができる。
前記燃料電池を備えることができる前記物品の具体例としては、ビル、家屋、テント等の建築物、蛍光灯、LED等、有機EL、街灯、屋内照明、信号機等の照明器具、機械、車両そのものを含む自動車用機器、家電製品、農業機器、電子機器、携帯電話等を含む携帯情報端末、美容機材、可搬式工具、風呂用品トイレ用品等の衛生機材、家具、玩具、装飾品、掲示板、クーラーボックス、屋外発電機などのアウトドア用品、教材、造花、オブジェ、心臓ペースメーカー用電源、ペルチェ素子を備えた加熱および冷却器用の電源が挙げられる。
[分析方法]
1.元素分析
炭素:試料約0.1gを量り取り、堀場製作所製EMIA-110にて測定を行った。
2.粉末X線回折測定
PANalytical社製X'Pert MPDを用いて、試料の粉末X線回折を測定した。X線光源にはCu‐Kαを使用した。
3.ラマン分光測定
日本分光製NRS―5100にて顕微ラマン測定を行った。試料測定前に、リファレンス用シリコン基板を用いて装置の校正を行った。試料測定は格子測定モードにて行い、9箇所の測定を1回とし、それぞれ異なる試料位置において、合計5回(計45箇所)測定した。各々の測定で得られたスペクトルを平均化し、最終結果とした。なお、励起波長は532nmであり、露光時間および積算回数は、レーザー照射点1箇所につきそれぞれ3秒および5回とした。
4.BET比表面積測定
試料を0.15g採取し、全自動BET比表面積測定装置マックソーブ(マウンテック社製)で比表面積測定を行った。前処理時間および前処理温度は、それぞれ30分および200℃に設定した。
5.透過型電子顕微鏡観察
透過型電子顕微鏡(TEM)観察を、日立製作所製H9500(加速電圧300kV)を用いて行った。観察試料は、試料粉体をエタノール中に超音波分散させた分散液を、TEM観察用マイクログリッド上に滴下することで作製した。また、日立製作所製HD2300(加速電圧200kV)を用いて、エネルギー分散型蛍光X線分析を行った。
[実施例1]
1-1.複合粒子の調製
チタンテトライソプロポキシド(純正化学製)5mLおよびアセチルアセトン(純正化学製)5mLをエタノール(和光純薬製)15mLと酢酸(和光純薬製)5mLとの溶液に加え、室温で攪拌しながらチタン含有混合物溶液を作成した。また、グリシン(和光純薬製)3.76gおよび酢酸鉄(II)(Aldrich社製)0.31gを純水20mLに加え、室温で攪拌して完全に溶解させたグリシン含有混合物溶液を作成した。チタン含有混合物溶液をグリシン含有混合物溶液にゆっくり添加し、透明な触媒前駆体溶液を得た。ロータリーエバポレーターを用い、ウォーターバスの温度を約80℃に設定し、前記触媒前駆体溶液を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形分残渣を乳鉢で細かく均一に潰して、粉末を得た。
1-2.過酸化水素処理
上記粉末1.6gを、蒸留水800mLと30%過酸化水素水(関東化学製)800mLとの混合溶液に添加し、攪拌しながら25℃にて2時間反応させた。この後、濾別、乾燥し、粉末(以下「触媒(1)」とも記す。)を得た。
1-3.白金担持操作
蒸留水1250mlに、触媒(1)1.00gおよび炭酸ナトリウム(和光純薬製)363mgを、超音波洗浄機で30分間振とうさせた。この懸濁液をウォーターバス中で液温を80℃に維持し、30分間攪拌した。ここに、塩化白金酸六水和物(和光純薬製)0.660g(白金0.250g相当)を含む蒸留水30mLを、10分かけて滴下した(液温は80℃に維持)。その後、液温80℃で2時間撹拌した。次に、37%ホルムアルデヒド水溶液(和光純薬製)21.5mlを上記懸濁液に5分かけて滴下した。その後、液温80℃で1時間撹拌した。反応終了後、上記懸濁液を冷却し、ろ過により黒色粉末を濾別、乾燥した。
[実施例2]
過酸化水素処理の反応時間を30分間にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(2)を調製した。さらに、触媒(1)の代わりに触媒(2)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(2)」とも記す。)を得た。
[実施例3]
過酸化水素処理の反応時間を8時間にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(3)を調製した。さらに、触媒(1)の代わりに触媒(3)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(3)」とも記す。)を得た。
[実施例4]
過酸化水素処理の反応温度を0℃にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(4)を調製した。さらに、触媒(1)の代わりに触媒(4)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(4)」とも記す。)を得た。
[実施例5]
5-1.複合粒子の調製
チタンテトライソプロポキシド(純正化学製)5mLおよびアセチルアセトン(純正化学製)5mLをエタノール(和光純薬製)15mLと酢酸(和光純薬製)5mLとの溶液に加え、室温で攪拌しながらチタン含有混合物溶液を作成した。また、グリシン(和光純薬製)3.76g及び酢酸鉄(II)(Aldrich社製)0.31gを純水20mLに加え、室温で攪拌して完全に溶解させたグリシン含有混合物溶液を作成した。チタン含有混合物溶液をグリシン含有混合物溶液にゆっくり添加し、透明な触媒前駆体溶液を得た。ロータリーエバポレーターを用い、ウォーターバスの温度を約80℃に設定し、前記触媒前駆体溶液を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形分残渣を乳鉢で細かく均一に潰して、粉末を得た。
5-2.白金担持操作
触媒(1)の代わりに触媒(5)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(5)」とも記す。)を得た。
[実施例6]
酢酸鉄(II)の代わりに、フェロシアン化アンモニウム(和光純薬製)を用いる以外は、実施例5の5-1と同様にして、触媒(6)を調製した。さらに、触媒(1)の代わりに触媒(6)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(6)」とも記す。)を得た。
[実施例7]
実施例6と同様にして触媒(6)を調製した。次に、実施例1の1-2と同様にして、触媒(6)を過酸化水素処理し、触媒(7)を得た。さらに、触媒(1)の代わりに触媒(7)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(7)」とも記す。)を得た。
[実施例8]
実施例7と同様にして触媒(7)を調製した。次に、蒸留水1250mlに、触媒(7)1.00g、および1.0mol/L水酸化ナトリウム水溶液(和光純薬製)21mLを添加し、超音波洗浄機で30分間振とうさせた。この懸濁液をウォーターバス中で液温を80℃に維持し、30分間攪拌した。ここに、塩化白金酸六水和物(和光純薬製)0.718g(白金0.270g相当)と、塩化コバルト(II)六水和物(関東化学製)0.330g(コバルト81.7mg相当)とを含む蒸留水30mLを、10分かけて滴下した(液温は80℃に維持)。その後、液温80℃で2時間撹拌した。次に、1.00gのヒドロホウ素化ナトリウム(和光純薬製)を含む蒸留水100mlを、上記懸濁液に10分かけて滴下した。その後、液温80℃で1時間撹拌した。反応終了後、上記懸濁液を冷却し、ろ過により黒色粉末を濾別、乾燥した。
[実施例9]
実施例7と同様にして触媒(7)を調製した。次に、蒸留水1250mlに、触媒(7)1.00g、および1.0mol/L水酸化ナトリウム水溶液(和光純薬製)21mLを添加し、超音波洗浄機で30分間振とうさせた。この懸濁液をウォーターバス中で液温を80℃に維持し、30分間攪拌した。ここに、塩化白金酸六水和物(和光純薬製)0.718g(白金0.270g相当)と、塩化ニッケル(II)六水和物(和光純薬製)0.331g(ニッケル81.7mg相当)とを含む蒸留水30mLを、10分かけて滴下した(液温は80℃に維持)。その後、液温80℃で2時間撹拌した。次に、1.00gのヒドロホウ素化ナトリウム(和光純薬製)を含む蒸留水100mlを、上記懸濁液に10分かけて滴下した。その後、液温80℃で1時間撹拌した。反応終了後、上記懸濁液を冷却し、ろ過により黒色粉末を濾別、乾燥した。
[比較例1]
1-1.複合粒子の調製
チタンテトライソプロポキシド(純正化学製)5mLおよびアセチルアセトン(純正化学製)5mLをエタノール(和光純薬製)15mLと酢酸(和光純薬製)5mLとの溶液に加え、室温で攪拌しながらチタン含有混合物溶液を作成した。また、グリシン(和光純薬製)3.76gを純水20mLに加え、室温で攪拌して完全に溶解させたグリシン含有混合物溶液を作成した。チタン含有混合物溶液をグリシン含有混合物溶液にゆっくり添加し、透明な触媒前駆体溶液を得た。ロータリーエバポレーターを用い、ウォーターバスの温度を約80℃に設定し、前記触媒前駆体溶液を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形分残渣を乳鉢で細かく均一に潰して、粉末を得た。
1-2.白金担持操作
触媒(1)の代わりに触媒(8)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(10)」とも記す。)を得た。
[比較例2]
2-1.複合粒子の調製の調製
チタンテトライソプロポキシド(純正化学製)5mLおよびアセチルアセトン(純正化学製)5mLをエタノール(和光純薬製)15mLと酢酸(和光純薬製)5mLとの溶液に加え、室温で攪拌しながらチタン含有混合物溶液を作成した。また、グリシン(和光純薬製)3.76gおよび酢酸鉄(II)(Aldrich社製)0.31gを純水20mLに加え、室温で攪拌して完全に溶解させたグリシン含有混合物溶液を作成した。チタン含有混合物溶液をグリシン含有混合物溶液にゆっくり添加し、透明な触媒前駆体溶液を得た。ロータリーエバポレーターを用い、ウォーターバスの温度を約80℃に設定し、前記触媒前駆体溶液を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形分残渣を乳鉢で細かく均一に潰して、粉末を得た。
2-2.白金担持操作
触媒(1)の代わりに触媒(9)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(11)」とも記す。)を得た。
[比較例3]
熱処理時の管状炉をULVAC-RIKO社製赤外線ゴールドイメージ炉とし、熱処理温度を900℃の代わりに1100℃にした以外は、比較例2の2-1と同様にして、触媒(10)を調製した。さらに、触媒(1)の代わりに触媒(10)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(12)」とも記す。)を得た。
[比較例4]
過酸化水素処理の反応温度を40℃にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(11)を調製した。さらに、触媒(1)の代わりに触媒(11)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(13)」とも記す。)を得た。
[比較例5]
過酸化水素処理の反応温度を60℃にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(12)を調製した。さらに、触媒(1)の代わりに触媒(12)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(14)」とも記す。)を得た。
[比較例6]
過酸化水素処理の反応温度を100℃にした以外は、上記実施例1の1-1、1-2と同様にして、触媒(13)を調製した。さらに、触媒(1)の代わりに触媒(13)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(15)」とも記す。)を得た。
[比較例7]
7-1.複合粒子の調製
炭化チタン(添川理化学製)5.10g、酸化チタン(和光純薬製)0.80g、窒化チタン(添川理化学製)0.31gをよく混合し、1800℃で3時間、窒素雰囲気中で加熱することにより、チタン炭窒化物粉末を得た。焼結体になるため、自動乳鉢で粉砕した。
7-2.白金担持操作
触媒(1)の代わりに触媒(14)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(16)」とも記す。)を得た。
[比較例8]
触媒(1)の代わりにルチル型酸化チタン(和光純薬製、以下「触媒(15)」とも記す。)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(17)」とも記す。)を得た。
[比較例9]
触媒(1)の代わりに炭化チタン(添川理化学製、以下「触媒(16)」とも記す。)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(18)」とも記す。)を得た。
[比較例10]
触媒(1)の代わりに窒化チタン(添川理化学製、以下「触媒(17)」とも記す。)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(19)」とも記す。)を得た。
[比較例11]
触媒(1)の代わりにチタン炭窒化物(アライドマテリアル社製、以下「触媒(18)」とも記す。)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(20)」とも記す。)を得た。
[比較例12]
12-1.複合粒子の調製
160℃に設定した加熱管に、四塩化チタン(純正化学製)を6g/hで供給し、さらに窒素ガスを1L/minで供給し、四塩化チタンガスおよび窒素ガスとの混合ガス(1)を得た。この混合ガス(1)を、図1に示したように反応器(1)に供給した。
12-2.白金担持操作
触媒(1)の代わりに触媒(19)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(21)」とも記す。)を得た。
[比較例13]
田中貴金属工業製の白金担持カーボン触媒(TEC10E50E)を、後述の各評価に前記複合触媒の代わりに用いた。以下、前記白金担持カーボン触媒をPt/Cと記す。白金担持カーボン触媒Pt/Cの、D/G比は1.13、BET比表面積は344m2/gであった。
[比較例14]
特許文献1の実施例1に従って、炭素化材料IK(Co)1000℃AWを合成した。この炭素化材料(以下「触媒(20)」とも記す。)を触媒(1)の代わりに用いた以外は、上記実施例1の1-3と同様にして、20質量%白金含有触媒(以下「複合触媒(22)」とも記す。)を得た。
[比較例15]
チタンテトライソプロポキシドを加えない以外は、上記比較例2の2-1と同様にして、触媒(21)を調製した。さらに、触媒(1)の代わりに触媒(21)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(23)」とも記す。)を得た。
[比較例16]
チタンテトライソプロポキシドを加えない以外は、上記実施例1の1-1、1-2と同様にして、触媒(22)を調製した。さらに、触媒(1)の代わりに触媒(22)を用いる以外は、上記実施例1の1-3と同様にして、20質量%白金含有複合触媒(以下「複合触媒(24)」とも記す。)を得た。
[透過型電子顕微鏡観察]
触媒(1)、触媒(6)、および、触媒(9)の透過型電子顕微鏡(TEM)観察像を図2の(a)、(b)、(c)にそれぞれ示す。図2において「5」はチタン化合物の一次粒子であり、「6」はグラファイト様カーボンであり、「7」はアモルファス様カーボンである。上記TEM観察および、エネルギー分散型蛍光X線分析より、いずれの担体においても、グラファイト様、あるいはアモルファス様の炭素構造体とともに、チタン化合物の一次粒子が観察された。ここで、チタン化合物一次粒子の二次凝集は観察されず、また、前記チタン化合物一次粒子が、前記カーボンの構造体中に分散している様子が確認された。特筆すべきは、触媒(9)と比較し、触媒(1)、および、触媒(6)では、アモルファス様カーボンが減少し、グラファイト様カーボンがより鮮明に観察されている。同様の傾向が、触媒(2)~触媒(5)、および触媒(7)においても確認された。
[粉末X線回折]
Cu‐Kα をX線光源とした、触媒(1)の粉末X線回折(XRD)パターンを図3に示す。参照系として測定した標準サンプル、ルチル型TiO2(和光純薬製)のXRDパターンとの比較から、触媒(1)の主相はルチル型酸化チタンと同定された。ここで、触媒(1)およびルチル型TiO2は、下記条件を満たす。すなわち、下記記載の2θ 範囲を占める領域A~D:
A:26~28°
B:35~37°
C:40~42°
D:53~55°
のそれぞれにピークを持ち、かつ回折パターンに現れる全てのピークの中で、最大の強度を持つピークが領域Aにある。触媒(2)~触媒(7)のXRDパターンにおいても、上記条件を満たす、触媒(1)と同様な回折ピーク群が観測され、主相はルチル構造を持つ酸化チタンと同定された。
[X線吸収分光]
触媒(1)~触媒(7)のX線吸収分光(XAS)測定を、大型放射光施設SPring-8にて行った。チタンの透過法X線吸収微細構造解析(透過法XAFS)において、X線吸収の閾値は、参照系として測定した標準サンプル、TiO2(チタンの価数4)、および、Ti2O3(チタンの価数3)の間の値であった。これより、触媒(1)~触媒(7)に含有されるチタンの価数は3.0より大きく4.0未満と見積もられた。
[元素分析、ラマン測定]
触媒(1)~触媒(19)の元素分析結果、ラマンスペクトルをピークフィッティングして得られた1340cm-1付近のピーク(Dバンド)の1580cm-1付近のピーク(Gバンド)に対する強度比(D/G比)およびBET法にて算出された比表面積を表1に示す。
[燃料電池用膜電極接合体の製造とその発電特性の評価]
1.カソード用インクの調製
上記実施例1に調製した複合触媒(1)33.7mgと、電子伝導性材料としてグラファイト化カーボンブラック(GrCB-K、昭和電工製)8.43mgとを混合し、さらにプロトン伝導性材料(ナフィオン(NAFION(登録商標))25.3mgを含有する水溶液(5%ナフィオン(NAFION(登録商標))水溶液、和光純薬製))0.506g、純水2.3mL、イソプロパノール(純正化学製)2.3mLを加え、氷水中で30分間超音波洗照射することにより、カソード用インク(1)を調製した。
2.燃料電池用触媒層を有するカソード電極の作製
ガス拡散層(カーボンペーパー(TGP-H-060、東レ製))を、アセトン(和光純薬製)に30秒間浸漬して脱脂した後、乾燥させ、次いで10%のポリテトラフルオロエチレン(PTFE)水溶液に30秒間浸漬した。
3.アノード用インクの調製
純水50mlに、白金担持カーボン触媒(田中貴金属工業製TEC10E70TPM)0.6gと、プロトン伝導性材料(ナフィオン(NAFION(登録商標))0.25gを含有する水溶液(5%ナフィオン(NAFION(登録商標))水溶液、和光純薬製))5gとを入れて、超音波分散機で1時間混合することにより、アノード用インク(1)を調製した。
4.燃料電池用触媒層を有するアノード電極の作製
ガス拡散層(カーボンペーパー(TGP-H-060、東レ製))を、アセトン(和光純薬製)に30秒間浸漬して脱脂した後、乾燥させ、次いで10%のポリテトラフルオロエチレン(PTFE)水溶液に30秒間浸漬した。
5.燃料電池用膜電極接合体の作製
電解質膜としてナフィオン(NAFION(登録商標))膜(NR-212、DuPont社製)を、カソードとして上記カソード(1)を、アノードとしてアノード(1)をそれぞれ準備した。
6.単セルの作製
上記5で作製したMEA(1)を、2つのシール材(ガスケット)、2つのガス流路付きセパレーター、2つの集電板および2つのラバーヒータで挟んでボルトで固定し、これらを所定の面圧(4N)になるように締め付けて、固体高分子形燃料電池の単セル(以下「単セル(1)」ともいう。)(セル面積:5cm2)を作製した。
7.起動停止耐久性試験
上記単セル(1)を80℃、アノード加湿器を80℃、カソード加湿器を80℃に温度調節した。この後、アノード側に燃料として水素を、カソード側に空気をそれぞれ供給し、単セル(1)の電流―電圧(I-V)特性を評価した。
[燃料電池用膜電極接合体の起動停止試験結果]
上記起動停止試験において、三角波電位サイクルを20000回印加した後のI-V測定から得られた、0.3A/cm2における電圧値の、三角波電位サイクルを印加する前のI-V測定から得られた、0.3A/cm2における電圧値(以下「初期電圧」とも記す。)に対する比(%)を電圧保持率と定義する。
2:四塩化チタンガスおよび窒素ガスとの混合ガス(1)
3:メタン、アンモニア、水および窒素との混合ガス(4)
4:反応物(捕集へ)
5:チタン化合物の一次粒子
6:グラファイト様カーボン
7:アモルファス様カーボン
Claims (18)
- チタン化合物の一次粒子がカーボンの構造体中に分散した複合粒子を含む酸素還元触媒であって、
前記複合粒子が、チタン、炭素、窒素、および酸素を構成元素として有し、前記各元素の原子数の比が、チタンを1とした場合に、炭素の比が2より大きく5以下、窒素の比が0より大きく1以下、酸素の比が1以上3以下であり、
かつラマンスペクトルにおけるDバンドのピーク強度の、Gバンドのピーク強度に対する強度比(D/G比)が0.4~1.0であることを特徴とする酸素還元触媒。 - 複合粒子が、鉄、ニッケル、クロム、コバルトおよびマンガンから選ばれる少なくとも1種の元素M2をさらに含み、かつ元素M2の総量のチタンに対する原子数の比が0.3以下である請求項1に記載の酸素還元触媒。
- 複合粒子が、Cu‐Kα 線を用いたX線回折(XRD)測定において、下記記載の2θ 範囲を占める領域A~D:
A:26~28°
B:35~37°
C:40~42°
D:53~55°
のそれぞれにピークを持ち、かつ回折パターンに現れる全てのピークの中で最大の強度を持つピークを領域Aに有する請求項1または2に記載の酸素還元触媒。 - 複合粒子の、透過法X線吸収微細構造解析(透過法XAFS)から求めたチタンの価数が3より大きく、4未満である請求項1~3のいずれかに記載の酸素還元触媒。
- さらに前記複合粒子に担持された貴金属または貴金属の合金からなる粒子を有する請求項1~4のいずれかに記載の酸素還元触媒。
- 貴金属が、白金、パラジウム、イリジウム、ロジウムおよびルテニウムから選ばれる少なくとも1種の貴金属である請求項5に記載の酸素還元触媒。
- 貴金属の合金が、貴金属同士の合金、または、貴金属と、鉄、ニッケル、クロム、コバルト、チタン、銅、バナジウムおよびマンガンから選ばれる少なくとも1種の金属とからなる合金である請求項5または6に記載の酸素還元触媒。
- 請求項1~7のいずれかに記載の酸素還元触媒を含むことを特徴とする燃料電池用触媒層作製用インク。
- 請求項8に記載の燃料電池用触媒層作製用インクを用いて作製されることを特徴とする燃料電池用触媒層。
- 請求項9に記載の燃料電池用触媒層を備えることを特徴とする燃料電池用電極。
- カソード触媒層とアノード触媒層と前記両触媒層の間に配置された高分子電解質膜とで構成される膜電極接合体であって、前記カソード触媒層および/または前記アノード触媒層が、請求項9に記載の燃料電池用触媒層であることを特徴とする膜電極接合体。
- 請求項11に記載の膜電極接合体を備えることを特徴とする燃料電池。
- 請求項1~7のいずれかに記載の酸素還元触媒の製造方法であって、
チタン含有化合物(1)、窒素含有有機化合物(2)および溶媒を混合して触媒前駆体溶液を得る工程1、
前記触媒前駆体溶液から溶媒を除去して固形分残渣を得る工程2、
工程2で得られた固形分残渣を700℃~1400℃の温度で熱処理して熱処理物を得る工程3、および
工程3で得られる熱処理物を、酸素原子を供与する酸化剤で酸化処理を行う工程4
を含み、前記チタン含有化合物(1)および前記窒素含有有機化合物(2)のうち少なくとも1つが酸素原子を有し、工程4の酸化はD/G比が0.4~1.0の範囲になるように調整されることを特徴とする酸素還元触媒の製造方法。 - 酸素原子を供与する酸化剤が、水、過酸化水素、過塩素酸および過酢酸から選ばれる少なくとも1種である請求項13に記載の酸素還元触媒の製造方法。
- 工程3の開始と同時または開始後に、工程4が工程3と重複して行われる請求項13に記載の酸素還元触媒の製造方法。
- 工程3と重複した工程4で使用される酸化剤が水である請求項15に記載の酸素還元触媒の製造方法。
- 工程3の終了後も工程4が行われる請求項15または16に記載の酸素還元触媒の製造方法。
- 工程4のうち工程3の終了後に行われる部分において用いられる酸化剤が過酸化水素、過塩素酸および過酢酸から選ばれる少なくとも1種である請求項17に記載の酸素還元触媒の製造方法。
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WO2015146490A1 (ja) * | 2014-03-25 | 2015-10-01 | 国立大学法人横浜国立大学 | 酸素還元触媒及びその製造方法 |
JP6397327B2 (ja) * | 2014-12-26 | 2018-09-26 | 昭和電工株式会社 | 酸素還元触媒およびその製造方法 |
JP6370467B2 (ja) * | 2015-02-18 | 2018-08-08 | 新日鐵住金株式会社 | 触媒担体用炭素材料、固体高分子形燃料電池用触媒、固体高分子形燃料電池、及び触媒担体用炭素材料の製造方法 |
KR101932612B1 (ko) * | 2017-04-25 | 2018-12-26 | 숭실대학교 산학협력단 | 산소환원반응을 위한 질소와 철이 도핑된 다공성 카본 나노입자 촉매 제조방법 |
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CN109994715B (zh) * | 2018-01-03 | 2021-08-24 | 国家纳米科学中心 | 一种自支撑电极及其制备方法和用途 |
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