Carbonaceous fired body, its complex, and fuel cell using the carbonaceous fired body

Abstract

When an electroconductive carbon material is used as a raw material to obtain a stable form in which the electroconductivity is maintained and / or improved, and when the stable form is used in a catalyst layer in a fuel cell, the power generation characteristics are improved.　The present invention is a sintered body, etc., of a mixture of an aromatic compound having phenolic hydroxyl groups and an electroconductive carbon material.

Description

Technical Field

[0001] The present invention relates to a carbon-based fired body, a complex thereof, and a fuel cell using the fired body.

Background Art

[0002] Carbon black of carbon materials is submicron fine particles composed of amorphous carbonaceous, and has uses such as a rubber reinforcing agent, a resin coloring agent, printing ink, paint, and an electrode material (Non-Patent Document 1). Among carbon blacks, carbon black that can impart conductivity with a small addition amount is called conductive carbon black, and depending on its production method and raw materials, for example, types such as acetylene black, oil furnace black, vulcan, ketjen black, and ketjen black EC are known (Non-Patent Document 2).

[0003] It is known that carbon black of carbon materials undergoes high-temperature production and activation treatment, so that some of the functional groups on the carbon black surface are desorbed and graphitization progresses to obtain high conductivity (Non-Patent Document 3).

[0004] Carbon nanotubes of carbon materials are composed of a cylindrical hexagonal network surface of carbon isotopes sp 2 It is composed of carbon and there are single-layer and multi-layer ones. For example, as carbon nanotubes manufactured and sold on an industrial scale, carbon nanotubes of vapor-grown carbon fibers are known and have excellent conductivity (Non-Patent Document 4).

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] For carbon materials having conductivity, for example, in the case of conductive carbon black, since its surface functional groups and defective parts are reduced by high-temperature firing to improve conductivity, the amount of surface functional groups of carbon black is small. Also, carbon nanotubes of carbon materials are composed of sp 2 Since they are composed of carbon, the functional groups on the surface of carbon nanotubes are concentrated at the edge sites and slight defective sites of the tubes, and their abundance is slight.

[0007] Therefore, it is possible to perform improvements such as imparting additional functions or enhancing functions through the surface functional groups of carbon black and carbon nanotubes without deteriorating the original conductive function, through chemical modification by organic synthesis methods, etc., or methods of introducing other materials by adsorption onto the surface of carbon black, etc. However, it has been difficult to perform improvements with practical significance. For example, in the case of chemical modification, the amount of functional groups that can be introduced is limited because the abundance of functional groups on the surface of the original carbon material having conductivity is small, and sp 2Introducing other functional groups to the surface composed of carbon using covalent bonds often led to a decrease in the original conductivity function depending on the introduced amount. In addition, since the method of adsorbing another material on the surface of a carbon material having conductivity is physical adsorption, the adsorption easily dissociates, and it was often the case that the properties of the material could not be maintained and decreased.

[0008] An object of the present invention is to obtain a stable form that retains and / or improves the conductivity of a carbon material having conductivity as a raw material, and to improve the power generation characteristics when used in the catalyst layer of a fuel cell.

Means for Solving the Problems

[0009] As a result of repeated studies by the present inventors, a novel fired body was obtained by performing a firing reaction on a mixture of a conventional carbon material having conductivity and an aromatic compound having a phenolic hydroxyl group. When this fired body is used, for example, as an electrolyte and / or a catalyst carrier in the catalyst layer of a fuel cell and as an electrolyte of a solid electrolyte membrane, it was found that proton conductivity, electron conductivity, water transport, and gas permeability are improved in the catalyst layer, and excellent power generation characteristics are exhibited.

[0010] As a result of repeated studies by the present inventors, a production method of firing and complexing a mixture of a conventional carbon material having conductivity and an aromatic compound having a phenolic hydroxyl group at a temperature equal to or higher than the melting point of the aromatic compound having a phenolic hydroxyl group, or a production method of firing and complexing after passing through a mixture of a carbon material having conductivity and an organic solvent solution of an aromatic compound having a phenolic hydroxyl group at a specific temperature. When the fired body obtained by this method is used, for example, as an electrolyte and / or a catalyst carrier in the catalyst layer of a fuel cell and as an electrolyte of a solid electrolyte membrane, it was found that proton conductivity, electron conductivity, water transport, and gas permeability are improved in the catalyst layer, and excellent power generation characteristics are exhibited.

[0011] As a result of further investigations by the present inventors, by performing a reaction to introduce rare earth metal ions into the above-mentioned fired body, a complex of the rare earth metal ions and the fired body is obtained, and it has been found that this complex improves proton conductivity and electron conductivity and exhibits excellent power generation characteristics.

[0012] The present invention is, for example, the following [1] to

[20] . [1] A carbon-based fired body of a mixture of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity. [2] The carbon-based fired body of [1], wherein the aromatic compound having a phenolic hydroxyl group is an aromatic compound having 2 to 6 phenolic hydroxyl groups. [3] The carbon-based fired body of [1] or [2], wherein the carbon material having conductivity is at least one selected from the group consisting of ketjen black, ketjen black EC, and carbon nanotubes. [4] A method for producing a carbon-based fired body according to any one of [1] to [3], comprising a step of obtaining a mixture of a melt or an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity. [5] (Step 1) A step of obtaining a mixture of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, and (Step 2) A step of firing the mixture obtained in Step 1 at a temperature equal to or higher than the melting point of the aromatic compound having a phenolic hydroxyl group The method for producing a carbon-based fired body according to [4], which comprises. [6] (Step 1) A step of obtaining a mixture of an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, and (Step 2) A step of firing the mixture obtained in Step 1 in a temperature range of 150°C to 600°C. The method for producing a carbon-based fired body according to [4], which comprises. [7] A complex of a fired body according to any one of [1] to [3] and a rare earth metal ion, wherein the rare earth metal ion forms a complex with a substituent of the fired body. [8] The complex of [7], wherein at least one metal species of the rare earth metal ions is selected from the group consisting of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. [9] The complex of [7] or [8], wherein the substituent of the fired body is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, an oxysulfonic acid group, a carboxylic anhydride structure, a chromene structure, a lactone structure, an ester structure, and an ether structure derived from a carbon material having conductivity, and a hydroxyl group derived from an aromatic compound having a phenolic hydroxyl group.

[10] A method for producing the complex of any one of [7] to [9], wherein a rare earth metal compound and the fired body according to any one of claims 1 to 3 are reacted in a solvent.

[11] The method for producing

[10] , wherein the rare earth metal compound is at least one selected from the group consisting of CeBr3, CeCl3·7H2O, CeF3, CeF4, CeI3, EuBr3·xH2O, EuCl2, EuCl3, EuCl3·6H2O, EuF3, EuI2, NdBr3, NdCl3, NdCl3·6H2O, NdF3, NdI2, NdI3, SmBr3, SmCl3, SmCl3·6H2O, SmI2, SmI3, Ce(NH4)2(NO3)6, Ce(NO3)3·6H2O, Nd(NO3)3·6H2O, Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, Eu(CH3CO2)3·xH2O, CeO2, Eu2O3, Nd2O3, Sm2O3, Sc2O3, (CeO2)(ZrO2), and samarium triisopropoxide.

[12] A method for producing the complex of any one of [7] to [9], wherein a mixture of a rare earth metal compound and the fired body according to any one of [1] to [3] is fired.

[13] The production method of

[12] , wherein the rare earth metal compound is at least one selected from the group consisting of Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, Eu(CH3CO2)3·xH2O, Gd(CH3CO2)3·xH2O, Gd(C5H7O2)3·xH2O, La(CH3CO2)3·xH2O, La(C5H7O2)3·xH2O, Tb(CH3CO2)3·xH2O, Yb(C2H3O2)3·4H2O, cerium triisopropoxide, samarium triisopropoxide, tris(acetylacetonato)cerium(III), and tris(acetylacetonato)samarium(III).

[14] The fired body of any one of [1] to [3] or the complex of any one of [7] to [9], which is at least one of the electrolyte in the catalyst layer of the solid polymer fuel cell, the catalyst carrier in the catalyst layer, and the electrolyte in the solid electrolyte membrane.

[15] A composition containing at least one selected from the group consisting of the fired body of any one of [1] to [3] and the complex of any one of [7] to [9], and a metal catalyst.

[16] The composition of

[15] for use in the catalyst layer of a solid polymer fuel cell.

[17] A catalyst layer for a solid polymer fuel cell having the composition of

[15] .

[18] A membrane electrode assembly having a solid electrolyte membrane, a gas diffusion layer, and the catalyst layer for a solid polymer fuel cell of

[17] .

[19] The membrane electrode assembly of

[18] , wherein the thickness of the solid electrolyte membrane is 10 to 100 μm.

[20] A solid polymer fuel cell having the membrane electrode assembly of

[18] or

[19] .

Advantages of the Invention

[0013] The carbon-based fired body and complex of the present invention are stable forms using a carbon material having conductivity as part of the raw materials, and when used in the catalyst layer of a fuel cell, they improve the power generation characteristics.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0015] In this specification, "n-" means normal, "s-" means secondary, "t-" means tertiary, "o-" means ortho, "m-" means meta, and "p-" means para.

[0016] <<Fired body>> The present invention relates to a carbon-based fired body of a mixture of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity.

[0017] <Aromatic compound having a phenolic hydroxyl group> Examples of the aromatic compound having a phenolic hydroxyl group include monocyclic or condensed polycyclic aromatic compounds having one or more phenolic hydroxyl groups.

[0018] Among these, 1-6 valent phenols, which are monocyclic aromatic compounds having 1 to 6 phenolic hydroxyl groups, can be mentioned. A monocyclic aromatic compound, examples of phenols having one phenolic hydroxyl group include, for example, phenol, ethylphenol, p-t-butylphenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, thymol, mesitol, busoidcumenol, 2,6-di-t-butyl-p-cresol, pentamethylphenol, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, capicole, o-allylphenol, anol, diethylstilbestrol, p-(methylthio)phenol, o-aminophenol, m-aminophenol, p-aminophenol, o-(methylamino)phenol, m-(methylamino)phenol, p-(methylamino)phenol, m-(dimethylamino)phenol, o-anilinophenol, m-anilinophenol, p-anilinophenol, 2-amino-p-cresol, 3-amino-o-cresol, 3-amino-p-cresol, 4-amino-o-cresol, 4-amino-p-cresol, 5-amino-o-cresol, 6-amino-m-cresol, 2,4-diaminophenol or 2,4,6-triaminophenol, etc.

[0019] A monocyclic aromatic compound, examples of phenols having two phenolic hydroxyl groups include, for example, catechol, resorcinol, hydroquinone, 3,4-toluenediol, 2,5-toluenediol, 3,5-toluenediol, 2,4-toluenediol, urshiol, p-xylene-2,6-diol, m-xylene-4,6-diol, p-xylene-2,5-diol or 2-isopropyl-5-methylhydroquinone, etc.

[0020] A monocyclic aromatic compound, examples of phenols having three phenolic hydroxyl groups include, for example, pyrogallol, 1,2,4-benzenetriol, phloroglucinol, 2-methylphloroglucinol, m-xylene-2,4,6-triol or 2,4,6-trimethylphloroglucinol, etc.

[0021] It is a monocyclic aromatic compound. Examples of phenols having four phenolic hydroxyl groups include 1,2,3,5-benzenetetraol or 1,2,4,5-benzenetetraol. It is a monocyclic aromatic compound. Examples of phenols having six phenolic hydroxyl groups include hexahydroxybenzene.

[0022] From the viewpoint of obtaining good power generation characteristics, as the monocyclic aromatic compound having a phenolic hydroxyl group, di- to hexavalent phenols which are monocyclic aromatic compounds having 2 to 6 phenolic hydroxyl groups are preferable, tri- to hexavalent phenols which are monocyclic aromatic compounds having 3 to 6 phenolic hydroxyl groups are more preferable, trivalent phenols which are monocyclic aromatic compounds having 3 phenolic hydroxyl groups are even more preferable, and phloroglucinol represented by the following formula (I) is particularly preferable.

[0023]

Chemical formula

[0024] Examples of the condensed polycyclic aromatic compound include naphthalene, azulene, heptalene, biphenylene, acenaphthylene, fluorene, phenalene, phenanthrene, anthracene, aceanthrylene, triphenylene, pyrene, chrysene, tetracene, perylene, pentacene, picene or coronene. From the viewpoint of obtaining good power generation characteristics, naphthalene, anthracene and triphenylene are preferable.

[0025] Examples of the condensed polycyclic aromatic compound having a phenolic hydroxyl group include 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,4-dihydroxynaphthalene, 2,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 1,3,8-trihydroxynaphthalene, 9,10-dihydroxyanthracene, 2,3,6,7,10,11-hexahydroxytriphenylene, etc. Preferably, a condensed polycyclic aromatic compound having 2 to 6 phenolic hydroxyl groups is exemplified. More preferably, 2,6-dihydroxynaphthalene, 1,3,8-trihydroxynaphthalene, 9,10-dihydroxyanthracene, and 2,3,6,7,10,11-hexahydroxytriphenylene are exemplified. Even more preferably, 2,3,6,7,10,11-hexahydroxytriphenylene represented by the following formula (II) is exemplified.

[0026]

Chemical formula

[0027] The aromatic compound having a phenolic hydroxyl group may be used alone or in combination of two or more.

[0028] <Conductive carbon material> Examples of the conductive carbon material (hereinafter also referred to as "carbon material") include carbon black, carbon nanotubes, etc. Examples of carbon black include Ketjen black, Ketjen black EC, channel black, oil furnace black, vulcan, furnace black, thermal black, acetylene black, lamp black, graphitized black, oxidized black, etc. Since they have good conductivity, acetylene black, Ketjen black, and Ketjen black EC are preferred, and Ketjen black and Ketjen black EC are more preferred. The carbon black may be used alone or in combination of two or more kinds. The carbon black may be surface-treated.

[0029] Examples of carbon nanotubes include single-walled nanotubes and multi-walled carbon nanotubes obtained by, for example, vapor phase growth method, catalytic vapor phase growth method, catalytic chemical vapor deposition method, chemical vapor deposition method, super growth method, catalytic carbon deposition method, arc discharge method, laser evaporation method, etc. These can take any form such as needle-like, coil-like, tube-like forms. Regarding the tubes of carbon nanotubes, they have a shape formed by winding one sheet of the graphite carbon hexagonal network into a cylindrical shape, multi-walled carbon nanotubes (multi-wall carbon nanotubes) obtained by winding one sheet of graphite into three or more layers, single-walled carbon nanotubes (single-wall carbon nanotubes: SWNT) obtained by winding one sheet of graphite into one layer, double-walled carbon nanotubes (double-wall carbon nanotubes: DWNT) obtained by winding one sheet of graphite into two layers, vapor-grown carbon fibers (VGCF, a registered trademark of Showa Denko KK), etc. Specifically, TC series such as TC-2010, TC-2020, TC-3210L, TC-1210LN (manufactured by Toda Kogyo Corporation), Sparkloes method CNT (manufactured by National Institute of Advanced Industrial Science and Technology), eDIPS-CNT (manufactured by National Institute of Advanced Industrial Science and Technology), SWNT series (product name, manufactured by Meijo NanoCarbon Co., Ltd.), VGCF (registered trademark) series such as VGCF, VGCF-H, VGCF-X (manufactured by Showa Denko KK: registered trademark), FloTube series (product name, manufactured by CNano Technology), AMC (product name, manufactured by Ube Industries, Ltd.), NANOCYL NC7000 series (product name, manufactured by Nanocyl S.A.), Baytubes (product name, manufactured by Bayer), GRAPHISTRENGTH (product name, manufactured by Arkema), MWNT7 (product name, manufactured by Hodogaya Chemical Co., Ltd.), Hyperion CNT (product name, manufactured by Hyperprion Catalysis International), etc. are mentioned. The TC series such as TC-2010, TC-2020, TC-3210L, TC-1210LN and the VGCF (registered trademark) series such as VGCF, VGCF-H, VGCF-X are preferred.

[0030] The carbon nanotubes may be used alone or in combination of two or more. The carbon nanotubes may be surface-treated. Further, carbon black and carbon nanotubes may be used in combination. As the carbon material having conductivity, at least one selected from the group consisting of ketjen black, ketjen black EC, and carbon nanotubes is particularly preferable.

[0031] The carbon material having conductivity preferably has at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, an oxysulfonic acid group, a carboxylic anhydride structure, a chromene structure, a lactone structure, an ester structure, and an ether structure, more preferably has at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, a carboxylic anhydride structure, a lactone structure, an ester structure, and an ether structure, and still more preferably has at least one substituent selected from the group consisting of a hydroxyl group, a lactone structure, an ester structure, and an ether structure.

[0032] [[Manufacturing Method of Carbon-Based Sintered Body]] The manufacturing method of the carbon-based sintered body of the present invention is a manufacturing method of a carbon-based sintered body of a mixture of a molten liquid or an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, which includes a step of obtaining a mixture of the aromatic compound having a phenolic hydroxyl group and the carbon material having conductivity.

[0033] When the aromatic compound having a phenolic hydroxyl group has a melting point lower than the firing temperature and does not decompose at the firing temperature, the manufacturing method of the carbon-based sintered body may include both a step of bringing a molten liquid of the aromatic compound having a phenolic hydroxyl group into contact with the carbon material having conductivity and a step of bringing an organic solvent solution of the aromatic compound having a phenolic hydroxyl group into contact with the carbon material having conductivity.

[0034] The manufacturing method of the carbon-based fired body has such steps that, before firing at the firing temperature, an aromatic compound having a phenolic hydroxyl group contacts the carbon material in a molten liquid or organic solvent solution state. In this state, it is considered that the aromatic compound having a phenolic hydroxyl group contacts the carbon material at the molecular level, and some interaction occurs between the aromatic compound having a phenolic hydroxyl group and the carbon material.

[0035] The manufacturing method of the carbon-based fired body is preferably the following Manufacturing Method 1 or Manufacturing Method 2. <Manufacturing Method 1> (Step 1) A step of obtaining a mixture of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material, and (Step 2) A step of firing the mixture obtained in Step 1 at a temperature equal to or higher than the melting point of the aromatic compound having a phenolic hydroxyl group A manufacturing method of a carbon-based fired body of a mixture of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material having the above steps.

[0036] <Manufacturing Method 2> (Step 1) A step of obtaining a mixture of an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material, and (Step 2) A step of firing the mixture obtained in Step 1 in a temperature range of 150°C to 600°C A manufacturing method of a carbon-based fired body of a mixture of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material having the above steps.

[0037] In Manufacturing Methods 1 and 2, the step of obtaining a mixture of a molten liquid of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material may exist between Step 1 and Step 2 as a temperature rising step for firing, or may be performed in Step 2, because it is sufficient that the aromatic compound having a phenolic hydroxyl group is exposed to a temperature equal to or higher than the melting point. In Manufacturing Method 2, the step of obtaining a mixture of an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material is Step 1.

[0038] When the aromatic compound having a phenolic hydroxyl group has a melting point lower than the firing temperature and does not decompose at the firing temperature, it preferably has a step of obtaining a mixture of a melt of the aromatic compound having a phenolic hydroxyl group and a conductive carbon material. Either Production Method 1 or Production Method 2 is preferably selected, and Production Method 1 is more preferably selected. When the aromatic compound having a phenolic hydroxyl group has a high melting point, for example, 300 °C or higher, a melting point higher than the firing temperature, or no melting point, it preferably has a step of obtaining a mixture of an organic solvent solution of the aromatic compound having a phenolic hydroxyl group and a conductive carbon material, and Production Method 2 is preferably selected.

[0039] (1) Production Method 1 In Step 1 of Production Method 1, the mass ratio of the aromatic compound having a phenolic hydroxyl group to the conductive carbon material is preferably 0.1:1 to 5:1, more preferably 0.2:1 to 2:1, and even more preferably 0.5:1 to 1:1. When the mass ratio is within the above range, it is preferable from the viewpoint of obtaining good power generation characteristics without impairing the conductivity of the conductive carbon material.

[0040] In Production Method 1, as the mixing method in Step 1, a general mixing method can be adopted. For example, a mixing method using a shaker mixer, a Lodige mixer, a Julia mixer, a V blender, etc. can be mentioned.

[0041] In Production Method 1, the firing temperature in Step 2 is preferably equal to or higher than the melting point of the aromatic compound having a phenolic hydroxyl group and lower than the temperature at which the aromatic compound having a phenolic hydroxyl group decomposes. More preferably, it is 150 to 600 °C, even more preferably 180 to 500 °C, and most preferably 200 to 450 °C. By setting the temperature range in this way, the reaction between the aromatic compound having a phenolic hydroxyl group and the conductive carbon material proceeds sufficiently.

[0042] Firing is carried out at a firing temperature, preferably for 1 to 10 hours, more preferably for 1 to 5 hours. The firing is preferably carried out under an inert gas. Examples of the inert gas include nitrogen, argon, etc.

[0043] (2) Manufacturing method 2 In step 1 of manufacturing method 2, the mass ratio of the aromatic compound having a phenolic hydroxyl group in the organic solvent solution to the carbon material having conductivity is preferably 0.1:1 to 5:1, more preferably 0.2:1 to 2:1, and even more preferably 0.5:1 to 1:1. When the mass ratio is within the above range, it is preferable from the viewpoint of obtaining good power generation characteristics without impairing the conductivity of the carbon material having conductivity.

[0044] In manufacturing method 2, as the mixing method in step 1, a general mixing method can be adopted. For example, a mixing method using a shaker mixer, a Lodige mixer, a Julia mixer, a V blender, etc. can be mentioned.

[0045] The organic solvent only needs to be able to dissolve the aromatic compound having a phenolic hydroxyl group, and in practical use, it preferably has a solubility of 0.1% by mass or more, preferably 0.5% by mass or more. From the viewpoint of ease of removal by drying, an organic solvent having a boiling point of 250°C or lower is preferred. Examples of such organic solvents include ethers such as tetrahydrofuran, diethyl ether, and 1,2-dimethoxyethane; halogenated hydrocarbons such as methylene chloride, chloroform, and 1,2-dichloroethane; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, isopropanol, n-propanol, isobutanol, and n-butanol; aliphatic hydrocarbons such as n-heptane, n-hexane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; glycol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether (1-methoxy-2-propanol), and propylene glycol 1-monomethyl ether 2-acetate; and glycols such as ethylene glycol and propylene glycol. These solvents can be used alone or in combination of two or more. Among these solvents, alcohols, glycol ethers, and glycols are preferred from the viewpoint of compatibility with the aromatic compound having a phenolic hydroxyl group.

[0046] It is preferable to provide a step of drying the organic solvent after Step 1 and before firing in Step 2 for removal. For example, in order to obtain a homogeneous mixture and dry the organic solvent, it is placed in a container such as a crucible and dried while heating and stirring the contents. By performing such heating and stirring, even if undissolved residues of the aromatic compound having a phenolic hydroxyl group exist at room temperature, the undissolved residues can also dissolve in the organic solvent under heating and stirring. The drying temperature may be equal to or higher than the boiling point of the organic solvent and lower than the temperature at which the aromatic compound having a phenolic hydroxyl group melts or decomposes.

[0047] In the manufacturing method 2, the firing temperature in step 2 is more preferably 150 to 600 °C, even more preferably 180 to 500 °C, and most preferably 200 to 450 °C. By setting the temperature within such a range, the reaction between the aromatic compound having a phenolic hydroxyl group and the carbon material having conductivity can proceed sufficiently, and the decomposition of the aromatic compound having a phenolic hydroxyl group can be prevented.

[0048] The firing is preferably carried out at the firing temperature for 1 to 10 hours, more preferably 1 to 5 hours. The firing is preferably carried out in an inert gas. Examples of the inert gas include nitrogen, argon, and the like.

[0049] <<Complex of the carbon-based fired body and a rare earth metal ion in which the rare earth metal ion forms a complex with a substituent of the carbon-based fired body>> The carbon-based fired body of the present invention becomes a complex of the carbon-based fired body and a rare earth metal ion in which the rare earth metal ion forms a complex with a substituent of the carbon-based fired body, together with the rare earth metal ion. Examples of the metal species of the rare earth metal ion in the complex of the carbon-based fired body and the rare earth metal ion include scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium. It is preferably scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, and ytterbium, and more preferably scandium, yttrium, lanthanum, cerium, samarium, europium, and ytterbium. These may be used alone or in combination of two or more.

[0050] In the complex of the carbon-based fired body and the rare earth metal ion, the substituent of the carbon-based fired body and the rare earth metal ion form a complex. Examples of the complex structure between the substituent of the carbon-based fired body and the rare earth metal ion include a complex structure between a substituent derived from the surface of a conductive carbon material and a carbon defect portion and the rare earth metal ion, and a complex structure between a hydroxyl group derived from an aromatic compound having a phenolic hydroxyl group and the rare earth metal ion. These may be either one of the complex structures or both of the complex structures.

[0051] More specifically, it is preferable that the substituent of the fired body is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, an oxysulfonic acid group, a carboxylic anhydride structure, a chromene structure, a lactone structure, an ester structure, an ether structure derived from a conductive carbon material, and a hydroxyl group derived from an aromatic compound having a phenolic hydroxyl group.

[0052] Examples of the complex structure between a substituent derived from the surface of a conductive carbon material and a carbon defect portion and the rare earth metal ion include a bond between a monovalent anion formally deprotonated from at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, an oxysulfonic acid group, a carboxylic anhydride structure, a chromene structure, a lactone structure, an ester structure, and an ether structure derived from a carbon material and the rare earth metal ion. Preferably, the rare earth metal ion forms a complex structure with the substituent on the surface of the carbon material and the carbon defect portion via -O-. More preferably, due to the reason of increasing the stability, the rare earth metal ion forms a structure in which one or more cyclic structures, that is, chelate rings are formed via -O- with the surface of the carbon material. Examples of the complex structure between a hydroxyl group derived from an aromatic compound having a phenolic hydroxyl group and the rare earth metal ion include a complex structure between a partial structure represented by the following formula (A) formed by firing from an aromatic compound having a phenolic hydroxyl group and the rare earth metal ion, for example, a partial structure represented by formula (B). It is preferable that at least a part of the aromatic compound having a phenolic hydroxyl group is contained as a three-dimensional polymer represented by the following formula (A) in the carbon-based carbon-based fired body.

[0053] [Chemical formula]

[0054] Examples of the method for producing a complex of a carbon-based fired body and a rare earth metal ion include the following production method A and production method B. From the viewpoint of power generation characteristics, production method B is preferred. [Production method A of a complex of a carbon-based fired body and a rare earth metal ion] Production method A includes the following step 1A, and preferably further includes the following step 2A. A complex of the carbon-based fired body and a rare earth metal ion, in which the rare earth metal ion forms a complex structure with a substituent of the carbon-based fired body, can be produced by step 1A. From the viewpoint of durability, it is preferable to perform step 2A after step 1A.

[0055] [Step 1A] In step 1A, the carbon-based fired body of the present invention is reacted with a rare earth metal compound to obtain a complex of the carbon-based fired body and a rare earth metal ion in which a complex is formed between the rare earth metal ion and a substituent of the carbon-based fired body of the present invention. In step 1A, the reaction between the carbon-based fired body and the rare earth metal compound is carried out by reacting the carbon-based fired body and the rare earth metal compound in a solvent. The substituent of the carbon-based fired body used in the reaction of step 1A is preferably at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, anoxysulfonic acid group, carboxylic anhydride structure, chromene structure, lactone structure, ester structure and ether structure, more preferably has at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, carboxylic anhydride structure, lactone structure, ester structure and ether structure, and still more preferably is at least one selected from the group consisting of a hydroxyl group, lactone structure, ester structure and ether structure.

[0056] Examples of the rare earth metal compound used in step 1A include CeBr3, CeCl3·7H2O, CeF3, CeF4, CeI3, DyBr3, DyBr3·xH2O, DyCl3, DyCl3·6H2O, DyF3, DyI3, ErBr3·xH2O, ErCl3, ErCl3·6H2O, ErF3, ErI3, EuBr3·xH2O, EuCl2, EuCl3, EuCl3·6H2O, EuF3, EuI2, GdBr3, GdCl3, GdCl3·6H2O, GdCl3·xH2O, GdF3, GdI3, HoBr3, HoBr3·xH2O, HoCl3, HoCl3·6H2O, HoF3, LaBr3·xH2O, LaCl3·7H2O, LaCl3·xH2O, LaF3, LaI3, LuBr3, LuCl3, LuCl3·6H2O, LuF3, LuI3, NdBr3, NdCl3, NdCl3·6H2O, NdF3, NdI2, NdI3, PrBr3, PrBr3·xH2O, PrCl3, SmBr3, SmCl3, SmCl3·6H2O, SmI2, SmI3, ScBr3, ScCl3, ScCl3·6H2O, ScF3, ScI3, TbBr3, TbCl3, TbCl3·6H2O, TbF3, TbI3, TmBr3, TmCl3, TmCl3·6H2O, TmF3, YbBr3, YbBr3·xH2O, YbCl3, YbCl3·6H2O, YbF3, YbI2, YCl3, YCl3·6H2O, YF3, YI3, Ce(NH4)2(NO3)6, Ce(NO3)3·6H2O, Dy(NH4)2(NO3)6, Er(NO3)3·5H2O, Er(NO3)3·xH2O, Gd(NO3)3·6H2O, Ho(NO3)3·5H2O, La(NO3)3·6H2O, La(NO3)3·xH2O, Lu(NO3)3·xH2O, Nd(NO3)3·6H2O, Pr(NO3)3·6H2O, Sm(NO3)3·6H2O, Tb(NO3)3·5H2O, Tb(NO3)3·6H2O, Yb(NO3)3·5H2O, Ce(CH3CO2)3·xH2O, Eu(CH3CO2)3·xH2O, Gd(CH3CO2)3·xH2O, La(CH3CO2)3·xH2O, Tb(CH3CO2)3·xH2O, Yb(C2H3O2)3·4H2O CeO2, Dy2O3, Er2O3, Eu2O3, Gd2O3, Ho2O3, La2O3, Lu2O3, Nd2O3, Pr2O3, Pr6O 11 , Sm2O3, Sc2O3, Tb2O3, Tb4O7, Tm2O3, Yb2O3, Y2O3, In addition to AlCeO3, (CeO2)(ZrO2), etc., rare earth metal alkoxide compounds, rare earth metal acetylacetonate compounds, etc. may be mentioned. These may be used alone or in combination of two or more.

[0057] Specific examples of rare earth metal alkoxide compounds include, for example, rare earth metal triisopropoxides. Specific examples of rare earth metal triisopropoxides include scandium triisopropoxide, yttrium triisopropoxide, lanthanum triisopropoxide, cerium triisopropoxide, praseodymium triisopropoxide, neodymium triisopropoxide, promethium triisopropoxide, samarium triisopropoxide, europium triisopropoxide, gadolinium triisopropoxide, terbium triisopropoxide, dysprosium triisopropoxide, holmium triisopropoxide, erbium triisopropoxide, thulium triisopropoxide, ytterbium triisopropoxide, lutetium triisopropoxide, etc. Specific examples of rare earth metal acetylacetonate compounds include tris(acetylacetonato)scandium(III), tris(acetylacetonato)yttrium n-hydrate, tris(acetylacetonato)lanthanum(III) hydrate, tris(acetylacetonato)cerium(III), tris(acetylacetonato)neodymium(III), tris(acetylacetonato)promethium(III), tris(acetylacetonato)samarium(III), tris(acetylacetonato)europium(III), tris(acetylacetonato)gadolinium(III), tris(acetylacetonato)terbium(III), tris(acetylacetonato)dysprosium(III), tris(acetylacetonato)holmium(III), tris(acetylacetonato)erbium(III), tris(acetylacetonato)thulium(III), tris(acetylacetonato)ytterbium(III), tris(acetylacetonato)lutetium(III), etc. These may be in the form of hydrates.

[0058] Examples of rare earth metal compounds used in Step 1A include CeBr3, CeCl3·7H2O, CeF3, CeF4, CeI3, EuBr3·xH2O, EuCl2, EuCl3, EuCl3·6H2O, EuF3, EuI2, NdBr3, NdCl3, NdCl3·6H2O, NdF3, NdI2, NdI3, SmBr3, SmCl3, SmCl3·6H2O, SmI2, SmI3, Ce(NH4)2(NO3)6, Ce(NO3)3·6H2O, Nd(NO3)3·6H2O, Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, Eu(CH3CO2)3·xH2O, CeO2, Eu2O3, Nd2O3, At least one selected from the group consisting of Sm2O3, Sc2O3, (CeO2)(ZrO2), and samarium triisopropoxide is preferred. At least one selected from the group consisting of CeBr3, CeCl3·7H2O, CeF3, CeF4, CeI3, EuI2, NdI2, NdI3, SmBr3, SmCl3, SmCl3·6H2O, SmI2, SmI3, Ce(NH4)2(NO3)6, Ce(NO3)3·6H2O, Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, Sm2O3 and samarium triisopropoxide is more preferable.

[0059] Step 1A can also be carried out, for example, in the presence of a base such as sodium hydride, lithium hydride, sodium hydroxide, 1,8-diazabicyclo-5,4,0-undec-7-ene (DBU), trimethylamine, triethylamine, tripropylamine, N-ethylmethylbutylamine, tributylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, tribenzylamine and the like. Among these, sodium hydride and lithium hydride are preferable.

[0060] The solvent used in Step 1A may be any non-aqueous solvent that can disperse the carbon-based fired body and dissolve or disperse the rare earth metal compound. For example, cyclohexane, benzene, toluene, nitrobenzene, carbon tetrachloride, diethyl ether, tetrahydrofuran, isoxazole, 1,4-dioxane, cyclopentyl methyl ether, acetone, acetonitrile, nitromethane, dimethyl sulfoxide, N,N-dimethylformamide, sulfolane, 1,3-propane sultone, 1,4-butane sultone and the like can be mentioned. 1,3-Propane sultone is a target of the reaction but can also serve as a solvent. Toluene, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, 1,3-propane sultone are preferable, and tetrahydrofuran is more preferable.

[0061] The reaction temperature of Step 1A is preferably -10 to 200°C, more preferably 10 to 160°C, and even more preferably 15 to 140°C.

[0062] The reaction time of Process 1A is preferably 1 to 500 hours, more preferably 2 to 300 hours, and still more preferably 5 to 150 hours.

[0063] [Process 2A] In Process 2A, the complex of the carbonaceous fired body obtained in Process 1A and the rare earth metal is washed with an acid and water. Since the complex that has undergone Process 2A removes reactive substituents and impurities by washing before being used in a fuel cell device, the possibility of decomposition products damaging the fuel cell device can be minimized, resulting in excellent durability. As the acid used in Process 2A, for example, inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, sulfurous acid, nitrous acid, phosphoric acid, and organic acids such as acetic acid, lactic acid, oxalic acid, citric acid, formic acid, etc. can be used. From the perspective of a fuel cell device, sulfuric acid, which is less likely to leave impurities, is preferred.

[0064] <Method B for Producing a Complex of a Carbonaceous Fired Body and Rare Earth Metal Ions> Production method B includes the following Process 1B and preferably further includes the following Process 2B. The complex of the carbonaceous fired body and the rare earth metal ions, in which the rare earth metal ions form a complex structure with the substituents of the carbonaceous fired body, can be produced by Process 1B. Optionally, Process 2B may be carried out after Process 1B.

[0065] [Process 1B] In Process 1B, a mixture of the carbonaceous fired body of the present invention and a rare earth metal compound is fired to obtain a complex of the carbonaceous fired body and the rare earth metal ions in which a complex structure is formed between the rare earth metal ions and the substituents of the carbonaceous fired body.

[0066] The substituent of the carbon-based fired body used in the reaction of Step 1B is preferably at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, anoxysulfonic acid group, carboxylic anhydride structure, chromene structure, lactone structure, ester structure, and ether structure, more preferably having at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a formyl group, carboxylic anhydride structure, lactone structure, and ester structure, and even more preferably at least one selected from the group consisting of a hydroxyl group, lactone structure, ester structure, and ether structure.

[0067] Examples of the rare earth metal compound used in Step 1B include the same compounds as those described in Step 1A above.

[0068] Examples of the rare earth metal compound used in Step 1B include Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, Eu(CH3CO2)3·xH2O, Gd(CH3CO2)3·xH2O, Gd(C5H7O2)3·xH2O, La(CH3CO2)3·xH2O, La(C5H7O2)3·xH2O, Tb(CH3CO2)3·xH2O, Yb(C2H3O2)3·4H2O, cerium triisopropoxide, samarium triisopropoxide, and at least one selected from the group consisting of tris(acetylacetonato)cerium(III) and tris(acetylacetonato)samarium(III) are preferred. More preferably, at least one selected from the group consisting of Ce(CH3CO2)3·xH2O, Ce(C5H7O2)3·xH2O, samarium triisopropoxide, tris(acetylacetonato)cerium(III), and tris(acetylacetonato)samarium(III).

[0069] The firing temperature in Step 1B is preferably 100 to 1000 °C, more preferably 150 to 600 °C, and even more preferably 200 to 500 °C.

[0070] The firing time of Step 1B is preferably 1 to 500 hours, more preferably 2 to 300 hours, and even more preferably 5 to 150 hours.

[0071] The firing atmosphere of Step 1B can be carried out under the atmosphere and under an inert gas. As the atmosphere, air can be mentioned, and as the inert gas, nitrogen, argon, etc. can be mentioned. The firing atmosphere is preferably under an inert gas, and nitrogen is preferable as the inert gas.

[0072] [Step 2B] It is the same as [Step 2A].

[0073] [Uses of the Carbonaceous Sintered Body and the Complex] The carbonaceous sintered body and the complex can be used as an electrolyte, a catalyst carrier, and a solid electrolyte membrane in the catalyst layer of a polymer electrolyte fuel cell, and can improve the power generation characteristics of the fuel cell. Further, the carbonaceous sintered body and the complex can be used in the catalyst layer as a material for an electrode catalyst such as water electrolysis, and can improve the performance of the voltage balance of the power generation electrolytic cell of the fuel cell. An example of use in a fuel cell is described below.

[0074] [Polymer Electrolyte Fuel Cell] FIG. 1 is a cross-sectional view schematically showing the configuration of a polymer electrolyte fuel cell (hereinafter also referred to as a "fuel cell"). The polymer electrolyte fuel cell 100 has an anode catalyst layer 103, a cathode catalyst layer 105, and a solid electrolyte membrane 107 sandwiched between both catalyst layers, and each catalyst layer has a gas diffusion layer (hereinafter abbreviated as "GDL") 101 on the outside. This configuration is called a membrane electrode assembly (hereinafter abbreviated as "MEA"). The fuel cell usually has this MEA sandwiched between separators 109.

[0075] At least one of the anode catalyst layer 103 and the cathode catalyst layer 105 contains the carbonaceous fired body and / or the complex. Further, the solid electrolyte membrane 107 may also contain the carbonaceous fired body and / or the complex. From the viewpoint of suppressing the increase in overvoltage during high-current driving, it is preferable to use the carbonaceous fired body and / or the complex at least for the cathode catalyst layer 105.

[0076] The carbonaceous fired body and the complex have proton conductivity, electron conductivity, water transport, and gas permeability, and also have a function of supporting a catalyst from their structure. Therefore, they can be used as a catalyst carrier, an electrolyte, or both in the catalyst layer of a fuel cell, and as an electrolyte in the solid electrolyte membrane. The main functions of the carbonaceous fired body and the complex are the electron conductivity and specific surface area already possessed by the carbon material that is the matrix of the carbonaceous fired body and the complex, the proton transfer effect by phenolic hydroxyl groups imparted by aromatic compounds having phenolic hydroxyl groups after firing, the suppression of aggregation of the carbon material after firing and the improvement of the dispersion stability of the catalyst ink accompanying this effect, the improvement of the supporting ability of the solid catalyst, and the function of water transport by adsorption and desorption of water. Further, the pores of the carbon material itself are considered to have a function of gas diffusion.

[0077] The anode catalyst layer 103 and the cathode catalyst layer 105 are obtained by preparing a composition containing at least one selected from the group consisting of the carbonaceous fired body and the complex and a metal catalyst as a catalyst ink, and then applying and drying the catalyst ink on a target substrate. That is, the anode catalyst layer 103 and the cathode catalyst layer 105 have a composition containing a metal catalyst and at least one selected from the group consisting of the carbonaceous fired body and the complex.

[0078] The carbonaceous fired body and the complex are preferably one type of electrolyte and one type of catalyst carrier. By the carbonaceous fired body and the complex serving as both an electrolyte and a catalyst carrier, a catalyst carrier that did not conventionally have proton conductivity will also have proton conductivity, and an improvement in the electrical characteristics of the fuel cell and the like is expected.

[0079] A catalyst supported on a catalyst carrier is referred to as an electrode catalyst. In this specification, the anode catalyst layer 103 and the cathode catalyst layer 105 may be abbreviated as the catalyst layer.

[0080] As the metal catalyst contained in the catalyst ink, a known metal catalyst can be used without particular limitation. The main function of the metal catalyst used in such anode catalyst layer 103 and cathode catalyst layer 105 is to cause an electrochemical reaction. Examples of the metal catalyst include platinum, an alloy of platinum and other metals, a platinum-containing catalyst such as a core-shell having a platinum shell portion; and other metal catalysts. These may be used alone or in combination of two or more. Among these, from the viewpoint of catalytic activity, a platinum-containing catalyst is preferred. For example, a platinum catalyst TEC10E50E (manufactured by Tanaka Kikinzoku Kogyo K.K.) using carbon black as a catalyst carrier can be mentioned.

[0081] In the alloy of platinum and other metals, the metal constituting the alloy with platinum is not particularly limited as long as it is other than platinum. For example, boron, magnesium, aluminum, silicon, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, indium, tin, antimony, barium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, gold, lead, bismuth, lanthanum, cerium, etc. can be mentioned. These may be used alone or in combination of two or more.

[0082] The core-shell having a platinum shell portion has a core portion made of a metal other than platinum and a shell portion made of platinum. The metal used for the core portion is not particularly limited as long as it is other than platinum. For example, nickel, copper, palladium, silver, gold, iridium, titanium, iron, cobalt, ruthenium, osmium, chromium, molybdenum, tungsten can be mentioned. These may be used alone or in combination of two or more.

[0083] As the catalyst, a platinum-containing catalyst is preferably used, but it is not limited thereto. As other metal catalysts, noble metals such as gold, silver, ruthenium, rhodium, palladium, osmium, iridium, etc., base metals such as iron, nickel, manganese, cobalt, chromium, copper, zinc, molybdenum, tungsten, germanium, tin, etc., alloys of these noble metals and base metals, or compounds such as metal oxides and metal complexes can also be adopted. These may be used alone or in combination of two or more.

[0084] The composition used as the catalyst ink may contain, in addition to the metal catalyst and the carbon-based fired body and / or the complex, a catalyst carrier other than the carbon-based fired body and / or the complex, an electrolyte other than the carbon-based fired body and / or the complex, a binder, and a solvent. These components other than the solvent are included in at least one of the anode catalyst layer 103 and the cathode catalyst layer 105, similar to the metal catalyst and the carbon-based fired body and / or the complex.

[0085] Examples of the catalyst carrier other than the carbon-based fired body and / or the complex that may be included in the composition used as the catalyst ink include carbon blacks such as channel black, furnace black, and thermal black, activated carbon obtained by carbonizing and activating a material containing various carbon atoms, carbon materials such as coke, natural graphite, artificial graphite, and graphitized carbon. These may be used alone or in combination of two or more. Among these, carbon black is preferable as the catalyst carrier other than the carbon-based fired body and / or the complex because of its high specific surface area and excellent electronic conductivity. The main function of the catalyst carrier is to conduct electrons. Further, the main function of the catalyst carrier includes the transport of gas and water through the pores of the catalyst carrier.

[0086] In order to suppress a decrease in the electron conductivity in the electrode catalyst, a binder for binding catalyst carriers to each other can be used in the catalyst layer. Examples of the binder include fluorosulfonic acid polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-diene copolymer (EPDM), Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay), Flemion (registered trademark, manufactured by Asahi Glass), and Aciplex (registered trademark, manufactured by Asahi Kasei). These may be used alone or in combination of two or more.

[0087] Examples of the electrolyte other than the carbon-based fired body and / or the complex that may be included in the composition used as the catalyst ink include fluorosulfonic acid polymers such as Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay), Flemion (registered trademark, manufactured by Asahi Glass), and Aciplex (registered trademark, manufactured by Asahi Kasei), hydrocarbon-based sulfonic acid polymers, and partially fluorine-introduced hydrocarbon-based sulfonic acid polymers. These may be used alone or in combination of two or more. As the electrolyte other than the carbon-based fired body and / or the complex, perfluorosulfonic acid-based polymers such as Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and Aciplex (registered trademark, manufactured by Asahi Kasei Corporation) are preferable, and Nafion (registered trademark, manufactured by DuPont) is more preferable. The electrolyte can be used alone with the carbon-based fired body and / or the complex, or can be used as a mixture of the carbon-based fired body and / or the complex and the above-described electrolyte. The main function of the electrolyte in the catalyst layer is to conduct protons, but from the viewpoint that passing fuel gas and transporting water are also required at the same time, the electrolyte in the composition used as the catalyst ink preferably contains a perfluorosulfonic acid-based polymer such as Nafion together with the carbon-based fired body and / or the complex from the viewpoint of voltage characteristics in a high current region. The catalyst layer containing the carbon-based fired body and / or the complex can be used as a material for the catalyst layer with any of a fluorine-based sulfonic acid polymer, a hydrocarbon-based sulfonic acid polymer, and a partially fluorine-introduced hydrocarbon-based sulfonic acid polymer, which are materials for the solid electrolyte membrane, and it is preferable to use a fluorine-based sulfonic acid polymer and a partially fluorine-introduced hydrocarbon-based sulfonic acid polymer.

[0088] Examples of the solvent used in the composition used as the catalyst ink include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, pentanol, dimethyl sulfoxide, N,N-dimethylformamide, and the like. As the solvent, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and isobutyl alcohol are preferable. Two or more of the above-described solvents can be mixed and used. From the viewpoint of suppressing re-aggregation of the ink, facilitating coating, and further suppressing the residue of the solvent in the catalyst layer, water, ethanol, 1-propanol, and 2-propanol are more preferable as the solvent used in the catalyst ink.

[0089] The content of each component in the catalyst ink is appropriately adjusted according to the purpose. In the catalyst ink, in 100% by mass of the solid content excluding the mass of the solvent, the metal catalyst is preferably 14 to 44% by mass, more preferably 24 to 34% by mass. At least one selected from the group consisting of the carbon-based fired body and the complex is preferably 1 to 25% by mass, more preferably 5 to 20% by mass. When other electrolytes are included in the catalyst ink, they are preferably 20 to 45% by mass, more preferably 25 to 40% by mass. When other catalyst carriers are included in the catalyst ink, they are preferably 20 to 55% by mass, more preferably 25 to 45% by mass. When a binder is included in the catalyst ink, it is preferably 0 to 5% by mass, more preferably 0 to 3% by mass. Components listed as electrolytes and binders are included in the electrolyte in the above blending amounts. The solvent used in the catalyst ink is preferably 70 to 99% by mass, more preferably 80 to 96% by mass, per 100% by mass of the catalyst ink.

[0090] By adjusting the composition of the catalyst ink, functions and performances such as suppressing the decrease in electron conductivity, improving proton conductivity, improving gas diffusibility, enhancing the efficiency of water transport, and improving the mechanical strength of the catalyst layer can be improved.

[0091] The manufacturing method of the catalyst layer 103 and the catalyst layer 105 will be described. After preparing the catalyst ink, the catalyst ink is applied onto a target substrate and dried to form a catalyst layer. Examples of the target substrate include a solid electrolyte membrane, a GDL, a sheet made of a fluororesin, etc., and the catalyst layer can be formed by a known manufacturing method. When the catalyst ink is applied onto a sheet made of a fluororesin, the applied catalyst layer is transferred onto a solid electrolyte. As the sheet made of a fluororesin, a sheet made of polytetrafluoroethylene (PTFE) is common.

[0092] Examples of the composition of the catalyst ink include, for example, a composition of a catalyst ink in which the metal catalyst is platinum, the catalyst carrier is carbon black, and the electrolyte is the carbon-based fired body and / or the complex and Nafion (registered trademark, manufactured by DuPont), a composition of a catalyst ink in which the metal catalyst is platinum, the catalyst carrier is carbon black, and the electrolyte is the carbon-based fired body and / or the complex, and the like. Further, a composition of a catalyst ink in which the catalyst is platinum, the catalyst carrier is carbon black and the carbon-based fired body and / or the complex, or only the carbon-based fired body and / or the complex, and the electrolyte is the carbon-based fired body and / or the complex can be mentioned. Thus, a catalyst ink in which at least a part of the catalyst carrier is the carbon-based fired body and / or the complex is produced by subjecting a catalyst ink containing the carbon-based fired body and / or the complex and a metal catalyst to a pulverization treatment, and a catalyst ink containing a carbon-based fired body and / or the complex supporting a metal catalyst is obtained.

[0093] Examples of the pulverization treatment include a dry pulverization treatment and a wet pulverization treatment. Examples of the dry pulverization treatment include a ball mill, a planetary mill, a pin mill, a jet mill, and the like. Examples of the wet pulverization treatment include an ultrasonic homogenizer, an ultrasonic disperser, a bead mill, a sand grinder, a homogenizer, a wet jet mill, and the like. Among these, preferred pulverization treatments are a ball mill, a bead mill, an ultrasonic homogenizer, an ultrasonic disperser, and a homogenizer, and a bead mill, an ultrasonic homogenizer, and an ultrasonic disperser are particularly preferred. When performing the wet pulverization treatment, the solvent to be used is not particularly limited, but a solvent or the like used for the catalyst ink can be used.

[0094] The carbon-based fired body and / or the complex can be used at the time of preparing the catalyst ink, and power generation characteristics can be obtained by fabricating a membrane electrode assembly (MEA) and incorporating it into a single cell.

[0095] The ratio of the amount of the carbon-based fired body and / or the complex used in the catalyst layer is calculated by the following formula. In the following calculation formula, the masses of the electrode catalyst, the carbon-based fired body and / or the complex, the electrolyte, and the binder are the solid content masses obtained by subtracting moisture and solvent and are used in the calculation. Also, in the following calculation formula, the electrolyte and the electrode catalyst do not include the carbon-based fired body and / or the complex in the present invention.

[0096] Ratio of carbon-based fired body and / or complex (mass%) = [Mass of carbon-based fired body and / or complex / (Total mass in the catalyst layer (solid content mass))] × 100 (mass%) = [Mass of carbon-based fired body and / or complex / (Mass of electrode catalyst + Mass of electrolyte other than carbon-based fired body and / or complex + Mass of binder + Mass of carbon-based fired body and / or complex)] × 100 (mass%) The ratio of the carbon-based fired body and / or the complex is preferably 1 to 25%, more preferably 5 to 20%.

[0097] When the catalyst layer contains an electrolyte other than the carbon-based fired body and the complex, the mass ratio of the carbon-based fired body and / or the complex in the catalyst layer to the electrolyte other than the carbon-based fired body and the complex is preferably carbon-based fired body and / or complex:electrolyte other than carbon-based fired body and the complex = 1:1 to 1:10, more preferably 1:2 to 1:5.

[0098] Examples of the material of the solid electrolyte membrane 107 include the carbon-based fired body and / or the complex, fluorine-based sulfonic acid polymers such as Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay), Flemion (registered trademark, manufactured by Asahi Glass), and Aciplex (registered trademark, manufactured by Asahi Kasei), hydrocarbon-based sulfonic acid polymers, and partially fluorine-introduced hydrocarbon-based sulfonic acid polymers.

[0099] The film thickness of the solid electrolyte membrane 107 is preferably 10 to 100 μm, more preferably 20 to 60 μm, from the viewpoints of conductivity, durability, and gas cross-leakage.

[0100] The gas diffusion layer 101 is not particularly limited, but a porous material having conductivity is preferably used. Examples of such materials include carbon paper, non-woven fabric, felt, and non-woven fabric. Further, there is also a material in which a gas diffusion layer is coated with a microporous layer (hereinafter abbreviated as "MPL"), which is a coating layer mainly composed of a water-repellent resin and a carbon material, and it has been reported that water transport during power generation of a fuel cell can be effectively performed. The catalyst layer containing the carbon-based fired body and / or the complex can also use a gas diffusion layer having this MPL. In the power generation test of the present invention, a water-repellent carbon paper, which is a GDL having this MPL, was used.

Examples

[0101] Hereinafter, the synthesis examples and examples of the present invention will be described more specifically, but the present invention is not limited thereto. The analytical instruments and their conditions used in the synthesis examples and examples are as follows.

[0102] In the examples and comparative examples, IR measurement was performed by the germanium ATR method with an incident angle of 30 degrees using an apparatus named Nicolet 6700-Continiuum (manufactured by Thermo).

[0103] [Example 1: Production of Fired Body (1)] A mixture (2.09 g) of Ketjen black EC (manufactured by Lion Corporation, EC300J, 1.08 g) and phloroglucinol (melting point 220 °C, manufactured by Tokyo Chemical Industry Co., Ltd., 1.08 g) was placed in an alumina crucible. The crucible was placed in a tabletop gas displacement furnace KDF-75 (manufactured by Denken & High Dental), and after setting the nitrogen atmosphere with a nitrogen flow, the temperature was raised at 3 °C per minute, and firing was performed at a firing temperature of 250 °C for 2 hours. After firing, it was cooled to room temperature while maintaining the nitrogen atmosphere to obtain a black carbon-based fired body (1.91 g, corresponding to 91% by mass when the charged mass was 100% by mass). This black fired body was pulverized in an agate mortar to obtain a sample for evaluation.

[0104] IR measurement was carried out by the germanium ATR method. The chart of the IR measurement of the fired body (1) is shown in Fig. 2.

[0105] For comparison, IR measurement of the raw material Ketjenblack EC (manufactured by Lion Corporation, EC300J) was also carried out. The chart of the IR measurement of Ketjenblack EC is shown in Fig. 3.

[0106] When comparing Fig. 2 and Fig. 3, a new peak that was not present in the IR measurement chart of Ketjenblack EC was confirmed in the IR measurement chart of Fig. 2. In Fig. 2, the new peak is indicated by an arrow.

[0107] [Example 2: Production of Fired Body (2)] 5.67 g of a solution prepared by dissolving Ketjenblack EC (manufactured by Lion Corporation, EC300J, 0.27 g) and phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., 0.27 g) in 5.13 g of 1-methoxy-2-propanol was placed in an alumina crucible. While stirring the contents with a Teflon (registered trademark) stir bar on a hot stirrer set at 120 °C, the solvent was volatilized. Finally, the temperature of the hot stirrer was raised to 150 °C to dry the contents. Next, the crucible was placed in a tabletop gas replacement furnace KDF-75 (manufactured by Denken High Dental), and after setting a nitrogen atmosphere with a nitrogen flow, the temperature was raised at 3 °C per minute, and firing was carried out at 250 °C for 2 hours. After firing, it was cooled to 100 °C or lower while maintaining a nitrogen atmosphere. The contents of the alumina crucible were a black carbon-based fired body, which was 0.450 g (equivalent to 83% by mass when the charged amount was 100% by mass). This black fired body was pulverized in an agate mortar to obtain a sample for evaluation.

[0108] [Example 3: Production of Fired Body (3)] Ketjen black EC (manufactured by Lion Corporation, EC300J, 0.27 g), and 2,3,6,7,10,11 - hexahydroxytriphenylene (melting point above 390 °C, manufactured by Fujifilm Wako Pure Chemical Corporation, 0.27 g) were placed in an alumina crucible together with 13.77 g of a solution prepared by dissolving them in 13.23 g of 1 - methoxy - 2 - propanol. While stirring the contents with a Teflon stirrer on a hot stirrer set at 120 °C, the solvent was volatilized. Finally, the temperature of the hot stirrer was raised to 160 °C to dry the contents. Next, the crucible was placed in a tabletop gas replacement furnace KDF - 75 (manufactured by Denken High Dental), and after creating a nitrogen atmosphere with a nitrogen flow, the temperature was raised at a rate of 3 °C per minute, and firing was carried out at 350 °C for 2 hours. After firing, it was cooled to 100 °C or lower while maintaining the nitrogen atmosphere. The contents of the alumina crucible were a black carbon - based fired body, weighing 0.478 g (equivalent to 88% by mass when the charged amount was taken as 100% by mass). This black fired body was ground in an agate mortar to obtain a sample for evaluation.

[0109] [Example 4: Production of Fired Body (4)] Ketjen black EC (manufactured by Lion Corporation, EC300J, 0.27 g), and 2,3,6,7,10,11 - hexahydroxytriphenylene (manufactured by Fujifilm Wako Pure Chemical Corporation, 0.27 g) were placed in an alumina crucible together with 13.77 g of a solution prepared by dissolving them in 13.23 g of 1 - methoxy - 2 - propanol. While stirring the contents with a Teflon stirrer on a hot stirrer set at 120 °C, the solvent was volatilized. Finally, the temperature of the hot stirrer was raised to 160 °C to dry the contents. Next, the crucible was placed in a tabletop gas replacement furnace KDF - 75 (manufactured by Denken High Dental), and after creating a nitrogen atmosphere with a nitrogen flow, the temperature was raised at a rate of 3 °C per minute, and firing was carried out at 400 °C for 2 hours. After firing, it was cooled to 100 °C or lower while maintaining the nitrogen atmosphere. The contents of the alumina crucible were a black carbon - based fired body, weighing 0.450 g (equivalent to 83% by mass when the charged amount was taken as 100% by mass). This black fired body was ground in an agate mortar to obtain a sample for evaluation.

[0110] [Example 5: Production of Fired Body (5)] Carbon nanotubes (manufactured by Showa Denko KK, VGCF (registered trademark)-X, 0.305 g) and 2,3,6,7,10,11-hexahydroxytriphenylene (manufactured by Fujifilm Wako Pure Chemical Corporation, 0.300 g) were placed in an alumina crucible together with 14.70 g of a solution prepared by dissolving them in 14.095 g of 1-methoxy-2-propanol. While stirring the contents with a Teflon stirrer on a hot stirrer set at 120°C, the solvent was volatilized. Finally, the temperature of the hot stirrer was raised to 160°C to dry the contents. Subsequently, the crucible was placed in a tabletop gas displacement furnace KDF-75 (manufactured by Denken Hidentaru), and after setting the nitrogen atmosphere with a nitrogen flow, the temperature was raised at 3°C per minute, and firing was performed at 400°C for 2 hours. After firing, it was cooled to 100°C or lower while maintaining the nitrogen atmosphere. The contents of the alumina crucible were a black carbon-based fired body, weighing 0.518 g (equivalent to 86% by mass when the charged amount was 100% by mass). This black fired body was pulverized in an agate mortar to obtain a sample for evaluation.

[0111] [Comparative Example 1: Production of a fired body (6) obtained by firing only 2,3,6,7,10,11-hexahydroxytriphenylene] Using only 2,3,6,7,10,11-hexahydroxytriphenylene (manufactured by Tokyo Chemical Industry Co., Ltd., 0.21 g) as the raw material, it was produced in the same manner as in Example 1 except that the firing temperature was set at 350°C. A black fired product (0.18 g, equivalent to 86% by mass when the charged amount was 100% by mass) was obtained.

[0112] In the following test examples, the power generation test was conducted as follows. <Power Generation Test A of Fuel Cell> The fabricated MEA was 1 cm 2After incorporating it into a single cell (manufactured by Effcee Development Co., Ltd., JARI standard cell) having the electrode area, a power generation test of the fuel cell was conducted. Using a fuel cell evaluation system (manufactured by Toyo Technica Co., Ltd., AutoPEM), the evaluation was carried out with a hydrogen gas flow of 1 L / min and an air gas flow of 2 L / min at a temperature of 80°C and a relative humidity of 95%. The current density and voltage were measured using an electrochemical measurement system (manufactured by Bio-Logic Co., Ltd., SP-300). Also, the open circuit voltage (hereinafter abbreviated as "OCV") was measured. Note that the OCV is the potential in a state where no voltage or current is applied to the single cell.

[0113] [Test Example 1 (Power Generation Test Using Sintered Body (1))] The catalyst ink was prepared using an electrode catalyst which is platinum-supported carbon (manufactured by Tanaka Kikinzoku Kogyo K.K., platinum content: 46.5 mass%, product name "TEC10E50E"), sintered body (1), Nafion dispersion solution (manufactured by Wako Pure Chemical Industries, Ltd., product name "5% Nafion Dispersion Solution DE520 CS type"), and 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.). In a glass vial, the electrode catalyst, sintered body (1), Nafion dispersion solution, and 2-propanol were added in this order, and the dispersion solution was irradiated with ultrasonic waves for 30 minutes with the oscillation power set to High using an ultrasonic cleaner ASU-6 manufactured by AS ONE Corporation to prepare the catalyst ink. The catalyst ink preparation conditions are described below.

[0114] Catalyst Ink Preparation Conditions: Nafion Ratio (mass%) = [Nafion Solids Content (mass) / (Electrode Catalyst (mass) + Nafion Solids Content (mass) + Sintered Body (mass))] × 100 (mass%) was set to 29 mass%.

[0115] Sintered Body Ratio (mass%) = [Sintered Body (mass) / (Electrode Catalyst (mass) + Nafion Solids Content (mass) + Sintered Body (mass))] × 100 (mass%) It was adjusted to 16% by mass. Specifically, when the mass of the electrode catalyst was 27.5 mg, it was prepared as a catalyst ink by setting the Nafion dispersion solution (294.8 mg), the fired body (8.0 mg), and 2-propanol (1 mL). The Nafion dispersion solution (294.8 mg) corresponds to a Nafion solid content of 14.7 mg.

[0116] Catalyst ink coating conditions (preparation of decal): The catalyst ink was applied using a stage and an applicator targeting a Teflon sheet with an area of 8 cm × 8 cm and a thickness of 130 μm. By using the entire amount of the prepared catalyst ink, a decal with a catalyst layer having a platinum amount of 0.2 mg per 1 cm 2 was formed on the Teflon sheet. The sheet with the decal was cut out as a decal sheet with an area of 1 cm × 1 cm. The platinum coating weights of the anode and cathode were confirmed to be 0.2 mg by the mass difference between each decal and after transfer.

[0117] Process for producing MEA: The Membrane Electrode Assembly (hereinafter abbreviated as "MEA") was produced using a solid electrolyte membrane, a Gas Diffusion Layer (hereinafter abbreviated as "GDL"), and a decal using catalyst ink. As the GDL, carbon paper having an MPL (manufactured by SGL Carbon Japan Co., Ltd., product name "28BC") was used. A Nafion 212 membrane (registered trademark, manufactured by DuPont Co., Ltd., membrane thickness: 50 μm) cut out into a 5 cm × 5 cm square was placed in the center as the solid electrolyte membrane, and decals (area 1 cm × 1 cm) with a catalyst layer on the Teflon sheet were overlapped on both sides. Then, it was thermocompression bonded under the conditions of an upper and lower platen temperature of 134 °C (132 °C for Test Examples 1, 6 to 13, and Comparative Test Example 4), a load of 0.6 kN, and a pressure bonding time of 240 seconds (120 seconds for Test Examples 1, 6 to 13, and Comparative Test Example 4). After peeling off the Teflon sheet, a Catalyst Coated Membrane (hereinafter abbreviated as "CCM") was produced. The platinum coating weights of the anode and cathode were confirmed by the mass difference between the decal and after transfer. For the GDL, using carbon paper (manufactured by SGL Carbon Japan Co., Ltd., product name "28BC", area 1 cm × 1 cm), with the MPL layer side facing the solid electrolyte membrane side, after overlapping both the anode side and the cathode side, the JARI standard cell was tightened with a torque wrench in increments of 1 Nm up to 4 Nm to crimp the GDL and the CCM. Using the fabricated MEA, power generation test A of the fuel cell was conducted. The results of voltage and current density are shown in Table 1. The OCV was 0.954 V.

[0118] [Test Examples 2 - 5] Instead of the fired body (1), in Test Example 2, the fired body (2) was used, in Test Example 3, the fired body (3) was used, in Test Example 4, the fired body (4) was used, and in Test Example 5, the fired body (5) was used. An MEA was fabricated in the same manner as Test Example 1, except that 8.0 mg was used for each in the preparation of the catalyst ink. Using the fabricated MEA, power generation test A of the fuel cell was conducted. The results of voltage and current density are shown in Table 1. The OCV of Test Example 2 was 0.967 V, the OCV of Test Example 3 was 0.980 V, the OCV of Test Example 4 was 0.983 V, and the OCV of Test Example 5 was 0.985 V.

[0119] [Comparative Test Examples 1 - 3] Instead of the fired body (1), in Comparative Test Example 1, the fired body (6) was used, in Comparative Test Example 2, Ketjenblack EC was used, and in Comparative Test Example 3, a physical mixture of the fired body (6) and Ketjenblack EC (manufactured by Lion Corporation, EC300J) with the same mass was used. An MEA was fabricated in the same manner as Test Example 1, except that 8.0 mg was used for each in the preparation of the catalyst ink. Using the fabricated MEA, power generation test A of the fuel cell was conducted. The results of voltage and current density are shown in Table 1. The OCV of Comparative Test Example 1 was 0.936 V, the OCV of Comparative Test Example 2 was 0.974 V, and the OCV of Comparative Test Example 3 was 0.955 V.

[0120]

Table 1

[0121] When comparing the power generation characteristics with Comparative Test Examples 1 to 3 conducted in the power generation test of a fuel cell under the same conditions except that the materials added were different from those in Test Example 1, Test Examples 1 to 5 showed better results. From the comparison between Test Examples 1 to 5 and Comparative Test Examples 1 and 2, it can be seen that by using a fired body of a combination of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material, better power generation characteristics can be obtained than those of a fired body of an aromatic compound having a phenolic hydroxyl group alone and a conductive carbon material alone. From the comparison between Test Examples 1 to 5 and Comparative Test Example 3, it can be seen that a fired body of a combination of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material has better power generation characteristics than a combination of a fired body of an aromatic compound having a phenolic hydroxyl group and a conductive carbon material.

[0122] When comparing Test Examples 1 to 4 with Test Example 5, it can be seen that when using carbon nanotubes as the conductive carbon material, the power generation characteristics are superior to those when using Ketjenblack EC when the current density is high. When comparing Test Example 1 and Test Example 2, phloroglucinol with a melting point of 220 °C showed almost no difference in power generation characteristics between the case of mixing and firing with the carbon material as it was and the case of dissolving in a solvent and then mixing and firing with the carbon material.

[0123] From the above Test Examples 1 to 5, the fuel cell using the fired body obtained by the production method of the present invention has good power generation characteristics. In this power generation test, even in the region where the current density is 1.5 (A / cm 2 ), the voltage can be maintained at 0.3 V or more. This is considered to be because the generated water is discharged well and the diffusion of fuel oxygen (air) is improved, and it can be said that the water transport and gas permeability of the catalyst layer are improved. In addition, since the fired body of the present invention has a hydroxyl group, it can be said that the proton transfer effect is improved.

[0124] [Comparative Example 2: Production of a fired body (7) obtained by firing only phloroglucinol] It was produced in the same manner as in Example 1, except that only phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., 2.0 g) was used as the raw material. A black fired product (1.8 g, 90% recovery when the charged amount was 100%) was obtained.

[0125] IR measurement was performed by the germanium ATR method. Fig. 4 shows the IR measurement chart of the fired body (7).

[0126] [Example 6: Production of Fired Body (8)] It was produced in the same manner as in Example 1, except that a mixture (2.34 g) of ketjen black EC (manufactured by Lion Corporation, EC300J, 0.60 g) and phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., 1.80 g) mixed in a mortar was used as the raw material. A black fired product (1.91 g, 82% recovery when the charged amount was 100%) was obtained.

[0127] [Example 7: Production of Fired Body (9)] It was produced in the same manner as in Example 1, except that a mixture (2.29 g) of ketjen black EC (manufactured by Lion Corporation, EC300J, 1.80 g) and phloroglucinol (manufactured by Tokyo Chemical Industry Co., Ltd., 0.60 g) mixed in a mortar was used as the raw material. A black fired product (2.15 g, 94% recovery when the charged amount was 100%) was obtained.

[0128] [Example 8: Production of Fired Body (10)] It was produced in the same manner as in Example 1, except that a mixture (0.99 g) of ketjen black EC (manufactured by Lion Corporation, EC300J, 1.00 g) and 2,3,6,7,10,11 - hexahydroxytriphenylene (manufactured by Fujifilm Wako Pure Chemical Corporation, 1.00 g) mixed in a mortar was used, and the firing temperature was set at 350 °C. A black fired product (0.87 g, 88% recovery when the charged amount was 100%) was obtained.

[0129] [Example 9: Production of Fired Body (11)] As the raw material, a mixture (0.41 g) obtained by mixing Ketjenblack EC (manufactured by Lion Corporation, EC300J, 0.21 g) and 2,3,6,7,10,11 - hexahydroxytriphenylene (manufactured by Fujifilm Wako Pure Chemical Corporation, 0.21 g) in a mortar was used. It was manufactured in the same manner as in Example 1 except that the firing temperature was set at 400°C. A black fired product (0.35 g, 85% recovery when the charged amount was taken as 100%) was obtained.

[0130] [Comparative Example 3: Production of a fired body (12) obtained by firing only 2,3,6,7,10,11 - hexahydroxytriphenylene] As the raw material, only 2,3,6,7,10,11 - hexahydroxytriphenylene (manufactured by Tokyo Chemical Industry Co., Ltd., 0.21 g) was used. It was manufactured in the same manner as in Example 1 except that the firing temperature was set at 350°C. A black fired product (0.18 g, 86% recovery when the charged amount was taken as 100%) was obtained.

[0131] [Example 10: Production of a fired body (13)] As the raw material, a mixture (0.63 g) obtained by mixing carbon nanotubes (manufactured by Showa Denko KK, VGCF (registered trademark) - X, 0.32 g) and phloroglucinol (manufactured by Fujifilm Wako Pure Chemical Corporation, 0.32 g) in a mortar was used. It was manufactured in the same manner as in Example 1. A black fired product (0.52 g, 82% recovery when the charged amount was taken as 100%) was obtained.

[0132] [Example 11: Production of a complex (A) of a fired body (1) and a rare earth metal ion] The fired body (1) (1.00 g) produced in Example 1, tetrahydrofuran (50 mL), and tris(acetylacetonato)cerium(III) trihydrate (manufactured by Fuji Film Wako Chemicals, 4.67 g, 9.50 mmol) were successively added to a reaction vessel. Next, the powder of sodium hydride (240.0 mg, 10.0 mmol) was added to the reaction vessel in portions. The reaction mixture was placed in an oil bath set at 70 °C and stirred for 24 hours to conduct the reaction. After completion of the reaction, after bringing it to room temperature of 20 to 25 °C, ion-exchanged water (10 mL) and 2 mol / L sulfuric acid (20 mL) were added to the reaction vessel in this order and stirred for 1 hour. Next, this reaction mixture was filtered through a vacuum filter equipped with silica filter paper and then washed with 2 mol / L sulfuric acid (10 mL). Next, it was washed with ion-exchanged water until the hydrogen ion index (pH) of the filtrate became neutral. After adding this crude product to an eggplant flask, it was placed on an evaporator connected to a vacuum pump and dried at a bath temperature of 90 °C until a constant weight was obtained to obtain complex (A) as a black solid (1.792 g).

[0133] [Example 12: Production of Complex (B) of Fired Body (1) and Rare Earth Metal Ion] The fired body (1) (0.60 g) produced in Example 1, tetrahydrofuran (30 mL), and samarium triisopropoxide (manufactured by Fuji Film Wako Pure Chemical Industries, 2.00 g, 6.10 mmol) were successively added to a reaction vessel. Next, the powder of sodium hydride (240.0 mg, 10.0 mmol) was added to the reaction vessel in portions. The reaction mixture was placed in an oil bath set at 70 °C and stirred for 24 hours to conduct the reaction. After completion of the reaction, after bringing it to room temperature of 20 to 25 °C, ion-exchanged water (5 mL) and 2 mol / L sulfuric acid (10 mL) were added to the reaction vessel in this order and stirred for 1 hour. Next, this reaction mixture was filtered through a vacuum filter equipped with silica filter paper and then washed with 2 mol / L sulfuric acid (5 mL). Next, it was washed with ion-exchanged water until the hydrogen ion index (pH) of the filtrate became neutral. After adding this crude product to an eggplant flask, it was placed on an evaporator connected to a vacuum pump and dried at a bath temperature of 90 °C until a constant weight was obtained to obtain complex (B) as a black solid (0.779 g).

[0134] [Example 13: Production of Complex (C) of Fired Body (1) and Rare Earth Metal Ion] A mixture (2.09 g) obtained by mixing the fired body (1) (0.60 g) produced in Example 1 and tris(acetylacetonato)cerium(III) trihydrate (manufactured by Fujifilm Wako Chemicals, 1.05 g, 2.12 mmol) in a mortar was placed in an alumina crucible. The crucible was placed in a tabletop gas displacement furnace KDF-75 (manufactured by Denken High Dental), and after setting the nitrogen atmosphere with a nitrogen flow, the temperature was raised at 13 °C per minute, and firing was carried out at a firing temperature of 400 °C for 1 hour. After firing, it was cooled to room temperature while maintaining the nitrogen atmosphere, and the complex (C) was obtained as a black fired product (0.85 g, 51% recovery when the charged weight was 100%).

[0135] [Comparative Test Example 4 (Fired Body (7))] Instead of the fired body (1), in Comparative Test Example 4, an MEA was produced in the same manner as in Test Example 1, except that 8.0 mg of the fired body (7) was used in the preparation of the catalyst ink, respectively. Using the produced MEA, power generation test A of the fuel cell was carried out. The results of voltage and current density are shown in Table 2. The OCV of Comparative Test Example 4 was 0.953 V.

[0136] When comparing the power generation characteristics between Comparative Test Example 4 and Comparative Test Example 2, which were carried out in the power generation test of the fuel cell under the same conditions except that the added materials were different from those in Test Example 1, Test Example 1 showed better results. Therefore, it can be seen that the fired body of the mixture of the aromatic compound having a phenolic hydroxyl group and the carbon material having conductivity exhibits superior power generation characteristics than the fired body of the aromatic compound having a phenolic hydroxyl group alone and the fired body of the carbon material having conductivity alone.

[0137] [Test Example 6] An MEA was produced in the same manner as in Test Example 1, except that Nafion membrane 211 (membrane thickness 25 μm) was used instead of the Nafion membrane 212 (membrane thickness 50 μm) used in Test Example 1. Using the produced MEA, power generation test A of the fuel cell was carried out. The results of voltage and current density are shown in Table 2. The OCV was 0.972 V.

[0138] In Test Example 6, a Nafion membrane thinner than that in Test Example 1 was used, and it was found that the proton conductivity in the electrolyte membrane was improved and the power generation characteristics were further improved.

[0139] [Table 2]

[0140] [Test Examples 7 to 11] In Test Example 7, instead of the fired body (1), the fired body (8) was used; in Test Example 8, the fired body (9) was used; in Test Example 9, the fired body (10) was used; in Test Example 10, the fired body (11) was used; and in Test Example 11, the fired body (13) was used. An MEA was produced in the same manner as in Test Example 1, except that 8.0 mg of each was used in the preparation of the catalyst ink. Using the produced MEA, a power generation test A of the fuel cell was conducted. The results of the voltage and current density are shown in Table 3. The OCV of Test Example 7 was 0.971 V, the OCV of Test Example 8 was 0.950 V, the OCV of Test Example 9 was 0.988 V, the OCV of Test Example 10 was 0.981 V, and the OCV of Test Example 11 was 9.651 V.

[0141] [Table 3]

[0142] [Test Examples 12 and 13] In Test Example 12, instead of the fired body (1), the complex (B) was used; in Test Example 13, the complex (C) was used. An MEA was produced in the same manner as in Test Example 1. Using the produced MEA, a power generation test A of the fuel cell was conducted. The results of the voltage and current density are shown in Table 4. The OCV of Test Example 12 was 0.964 V, and the OCV of Test Example 13 was 0.980 V.

[0143] [Table 4]

[0144] From the above Test Examples 7 to 13, the fired body of the present invention and the complex of the rare earth metal and the fired body have good power generation characteristics. In the current power generation test, even in the region where the current density is 2 to 2.5 (A / cm 2 ), the voltage can be maintained at 0.2 V or more. This is considered to be because the generated water is discharged well and the diffusion of oxygen (air) of the fuel is improved, and it can be said that the water transport and gas permeability of the catalyst layer are improved. In addition, since the fired body and the complex of the present invention have a hydroxyl group, the transfer effect of protons is improved. And since the complex of the present invention is a complex of a rare earth metal, due to the effect of coordinating a large number of waters to the metal center of the complex of the rare earth metal, it can be said that the proton conductivity is improved.

Industrial Applicability

[0145] The fired body and the complex of the present invention are useful, for example, as electrolyte materials for fuel cells (for example, electrolytes used in catalyst layers, catalyst carriers, and electrolytes of solid electrolyte membranes), and an improvement in power generation characteristics and high durability of fuel cells are expected.

Explanation of Symbols

[0146] 100 Fuel cell 101 Gas diffusion layer 103 Anode catalyst layer 105 Cathode catalyst layer 107 Solid electrolyte membrane 109 Separator

Claims

1. A carbon-based fired body of a mixture of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, wherein the aromatic compound having a phenolic hydroxyl group is a monocyclic or condensed polycyclic aromatic compound and is a compound having one or more phenolic hydroxyl groups. The carbon-based fired body.

2. The carbon-based fired body according to Claim 1, wherein the aromatic compound having a phenolic hydroxyl group is an aromatic compound having 2 to 6 phenolic hydroxyl groups.

3. The carbon-based fired body according to Claim 1 or 2, wherein the carbon material having conductivity is at least one selected from the group consisting of ketjen black, ketjen black EC, and carbon nanotubes.

4. A method for producing a carbon-based fired body according to any one of Claims 1 to 3, comprising a step of obtaining a mixture of a melt or an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, wherein the aromatic compound having a phenolic hydroxyl group is a monocyclic or condensed polycyclic aromatic compound and is a compound having one or more phenolic hydroxyl groups. The method for producing a carbon-based fired body according to any one of Claims 1 to 3.

5. (Step 1) A step of obtaining a mixture of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, and (Step 2) A step of firing the mixture obtained in Step 1 at a temperature equal to or higher than the melting point of the aromatic compound having a phenolic hydroxyl group The method for producing a carbon-based fired body according to Claim 4, comprising:

6. (Step 1) A step of obtaining a mixture of an organic solvent solution of an aromatic compound having a phenolic hydroxyl group and a carbon material having conductivity, and (Step 2) A step of firing the mixture obtained in Step 1 in a temperature range of 150°C to 600°C. The method for producing a carbon-based fired body according to Claim 4.

7. A complex of the fired body according to any one of Claims 1 to 3 and a rare earth metal ion, wherein the rare earth metal ion forms a complex with a substituent of the fired body.

8. The complex according to Claim 7, wherein the metal species of the rare earth metal ion is at least one selected from the group consisting of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

9. The complex according to claim 7 or 8, wherein the substituent of the fired body is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, a sulfonic acid group, an oxysulfonic acid group, a carboxylic anhydride structure, a chromene structure, a lactone structure, an ester structure, an ether structure, and a hydroxyl group derived from an aromatic compound having a phenolic hydroxyl group, which are derived from a carbon material having conductivity.

10. A method for producing the complex according to any one of claims 7 to 9, wherein a rare earth metal compound and the fired body according to any one of claims 1 to 3 are reacted in a solvent.

11. The rare earth metal compound is CeBr ３ , CeCl ３ ·7H ２ O, CeF ３ , CeF ４ , CeI ３ , EuBr ３ ·xH ２ O, EuCl ２ , EuCl ３ , EuCl ３ ·6H ２ O, EuF ３ , EuI ２ , NdBr ３ , NdCl ３ , NdCl ３ ·6H ２ O, NdF ３ , NdI ２ , NdI ３ , SmBr ３ , SmCl ３ , SmCl ３ ·6H ２ O, SmI ２ , SmI ３ , Ce(NH ４ ) ２ (NO ３ ) ６ , Ce(NO ３ ) ３ ·6H ２ O, Nd(NO ３ ) ３ ·6H ２ O, Ce(CH ３ CO ２ ) ３ ·xH ２ O, Ce(C ５ H ７ O ２ ) ３ ·xH ２ O, Eu(CH ３ CO ２ ) ３ ·xH ２ O, CeO ２ , Eu ２ O ３ , Nd ２ O ３ , Sm ２ O ３ , Sc ２ O ３ , (CeO ２ )(ZrO ２ ) and at least one selected from the group consisting of samarium triisopropoxide, according to claim 10 of the manufacturing method described.

12. A method for producing the complex according to any one of claims 7 to 9, wherein a mixture of a rare earth metal compound and the fired body according to any one of claims 1 to 3 is fired.

13. The rare earth metal compound is Ce(CH ３ CO ２ ). ３ ·xH ２ O, Ce(C ５ H ７ O ２ ). ３ ·xH ２ O, Eu(CH ３ CO ２ ). ３ ·xH ２ O, Gd(CH ３ CO ２ ). ３ ·xH ２ O, Gd(C ５ H ７ O ２ ). ３ ·xH ２ O, La(CH ３ CO ２ ). ３ ·xH ２ O, La(C ５ H ７ O ２ ). ３ ·xH ２ O, Tb(CH ３ CO ２ ). ３ ·xH ２ O, Yb(C ２ H ３ O ２ ). ３ ·4H ２ O, and at least one selected from the group consisting of cerium triisopropoxide, samarium triisopropoxide, tris(acetylacetonato)cerium(III), and tris(acetylacetonato)samarium(III). The production method according to claim 12

14. The fired body according to any one of claims 1 to 3 or the complex according to any one of claims 7 to 9, which is at least one of an electrolyte in a catalyst layer of a polymer electrolyte fuel cell, a catalyst carrier in a catalyst layer, and an electrolyte in a solid electrolyte membrane.

15. A composition containing at least one selected from the group consisting of the fired body according to any one of claims 1 to 3 and the complex according to any one of claims 7 to 9, and a metal catalyst.

16. The composition according to claim 15, which is for a catalyst layer of a polymer electrolyte fuel cell.

17. A catalyst layer for a polymer electrolyte fuel cell having the composition according to claim 15.

18. A membrane electrode assembly having a solid electrolyte membrane, a gas diffusion layer, and the catalyst layer for a polymer electrolyte fuel cell according to claim 17.

19. The membrane electrode assembly according to claim 18, wherein the thickness of the solid electrolyte membrane is 10 to 100 μm.

20. A polymer electrolyte fuel cell having the membrane electrode assembly according to claim 18 or 19.

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