Carbon-based binder and polymer electrolyte fuel cell using the carbon-based binder

Abstract

Provided is a carbon-based conjugate having excellent proton conductivity and electron conductivity and exhibiting exceptional power generation characteristics when used in a catalyst layer of a polymer electrolyte fuel cell.　This carbon-based conjugate has a rare earth metal ion and a carbon-based solid acid that is bonded with the rare earth metal ion.

Description

[Technical Field]

[0001] The present invention relates to a carbon-based bond comprising a rare earth metal ion and a carbon-based solid acid. [Background technology]

[0002] Solid acids have anionic sites within their structure that immobilize hydrogen ions. Metal ions can be immobilized at these anionic sites by ion exchange in an aqueous solution containing metal cations, such as metal ions or complex ions. These solid acids are classified into organic and inorganic solid acids. Examples of organic solid acids include ion exchange resins containing acidic groups, such as sulfonic acid or carboxyl groups, within their molecules. These acidic groups serve as anionic sites that immobilize metal species. Organic solid acids facilitate the introduction of acidic groups into the resin, making it easy to enhance the anionic sites. However, they face challenges in terms of heat resistance, durability, and chemical resistance. On the other hand, inorganic solid acids, such as aluminum oxide, vanadium oxide, silica-alumina, and zeolite, are characterized by high heat resistance and solvent resistance, but due to their limited anionic sites, they are difficult to achieve higher ion exchange capacity and ion conduction capacity than organic solid acids.

[0003] Patent Documents 1 to 3 report that amorphous carbon obtained by heat-treating an organic compound in concentrated sulfuric acid or fuming sulfuric acid, followed by carbonization, sulfonation, and condensation of rings, can be used as a solid acid. This solid acid is called a carbon-based solid acid, a carbon-based solid acid, or a carbon solid acid. Non-Patent Document 1 also reports that a graphene sheet treated with sulfuric acid in the same manner as Patent Documents 1 to 3 is a carbon-based solid acid having sulfonic acid groups, carboxylic acid groups, and phenolic hydroxyl groups on the graphene sheet.

[0004] Regarding the use and applications of this carbon-based solid acid, for example, Patent Documents 1 to 3 report that this carbon-based solid acid is a solid acid with high catalytic performance and proton conductivity. Non-Patent Document 1 reports that it has high performance as a catalyst for hydrolyzing cellulose. Patent Document 4 reports a carbon-based solid acid that has high ion exchange capacity, catalytic performance, proton conductivity, and excellent heat resistance and can be used in proton conductive membranes, solid acid catalysts, ion exchange membranes, membrane electrode assemblies, and fuel cells. Patent Document 6 reports a catalyst precursor, catalyst material, and catalyst production method that use a carbon-based solid acid.

[0005] Regarding the synthesis, production methods, and raw materials of this carbon-based solid acid, for example, Non-Patent Document 1 reports a production method using crystalline cellulose as the main raw material and 30% oleum and concentrated sulfuric acid as sulfonating agents. Patent Documents 1 to 4 and 6 report production methods using aromatic hydrocarbons or the like as the main raw material and oleum and concentrated sulfuric acid as sulfonating agents. Furthermore, Patent Document 5 reports an industrial production method using pure cellulose, cellulose-containing raw materials, trees, plants, fruits, seeds, regenerated cellulose, or other carbon sources as the main raw material and sulfur trioxide as the sulfonating agent. Patent Document 7 reports a production method using naphthalene as the main raw material, a carbon source, and concentrated sulfuric acid as the sulfonating agent. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Masakazu Iwamoto, Catalyst Preparation Handbook, NTS Co., Ltd. (Tokyo), 2011, pp. 634-635 [Patent documents]

[0007] [Patent Document 1] International Publication No. 2005 / 029508 [Patent Document 2] Patent No. 4041409 [Patent Document 3] Patent No. 4582546 [Patent Document 4] Patent No. 4925399 [Patent Document 5] Patent No. 5528036 [Patent Document 6] Patent No. 5182987 [Patent Document 7] Patent No. 5017902 Summary of the Invention [Problem to be solved by the invention]

[0008] As reported in Patent Documents 3 and 4, carbon-based solid acids have sulfonic acid groups, which are strong acid groups, and are therefore expected to be materials that can be used in fuel cells, have high ion exchange capacity, catalytic performance, proton conductivity, and excellent heat resistance. However, while Patent Documents 3 and 4 report that these carbon-based solid acids can be used as electrolytes in proton-conductive membranes of fuel cells, they do not describe their use in the catalyst layer of fuel cells. Furthermore, there are no reports of actually fabricating fuel cells and confirming their operation.

[0009] Patent Document 6 describes a catalyst precursor, a catalyst material, and a catalyst production method that use a carbon-based solid acid, but there is no report of actually producing a fuel cell and confirming its operation. Patent Document 7 reports the use of a carbon-based solid acid in the catalyst layer of a polymer electrolyte fuel cell, and power is generated as a fuel cell by using Nafion (registered trademark, manufactured by DuPont Co., Ltd.) as an electrolyte and a carbon-based solid acid in the catalyst layer of the polymer electrolyte fuel cell. The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a carbon-based composite that has good proton conductivity and electron conductivity and exhibits excellent power generation characteristics when used in a catalyst layer of a polymer electrolyte fuel cell. [Means for solving the problem]

[0010] As a result of extensive investigations, the present inventors have found that by reacting a conventional carbon-based solid acid with a rare earth metal compound, a carbon-based bonded body can be obtained in which rare earth metal ions are introduced into the carbon-based solid acid in such a manner that the rare earth metal ions are bonded to substituents of the raw material carbon-based solid acid, and that this carbon-based bonded body has improved proton conductivity and electron conductivity and exhibits excellent power generation characteristics.

[0011] The present invention based on these findings is as follows. [1] A rare earth metal ion, A carbon-based bond having a rare earth metal ion and a carbon-based solid acid bonded thereto. [2] The carbon-based bond according to [1], 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. [3] The carbon-based bond according to [1] or [2], wherein the carbon-based solid acid has a graphene structure at least in part. [4] The carbon-based bond according to any one of [1] to [3], wherein the carbon-based solid acid has 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. [5] The carbon-based bond according to any one of [1] to [4], wherein the rare earth metal ion is bonded to a formally deprotonated monovalent anion via at least one substituent or structure 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 of the carbon-based solid acid. [6] A carbon-based bond according to any one of [1] to [5], having a structure represented by the following formula (1): [ka] (In formula (1), G represents graphene which may have at least one structure 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; Ln represents a metal ion selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium; A is one selected from -O-, -COO- and -SO3-, and when there are multiple As, they may be the same or different from each other; B is one group selected from -O-, -COO-, and -SO3-, or a hydroxyl group, and when there are multiple Bs, they may be the same or different from each other, C represents one group selected from -O-, -COO-, and -SO3-, or a hydroxyl group, and when there are multiple Cs, they may be the same or different from each other; When B and C are a group selected from -O-, -COO-, and -SO3-, they are each independently bonded to G to which A is bonded or to G different from G to which A is bonded; When B and C are hydroxyl groups, they are each independently bonded only to Ln; p is an integer between 1 and 18. [7] A catalyst layer of a polymer electrolyte fuel cell containing any one of the carbon-based binders described in [1] to [6]. [8] The catalyst layer of the polymer electrolyte fuel cell according to [7], wherein the carbon-based binder is a type of electrolyte and a type of catalyst carrier. [9] The catalyst layer of the polymer electrolyte fuel cell according to [7] or [8], further comprising a perfluoroacid polymer.

[10] A catalyst layer for a polymer electrolyte fuel cell according to any one of [7] to [9], further comprising a binder.

[11] A membrane electrode assembly having a solid polymer electrolyte membrane, a gas diffusion layer, and a catalyst layer according to any one of [7] to

[10] .

[12]

[11] A polymer electrolyte fuel cell having a membrane electrode assembly.

[13] A method for producing a carbon-based bond, comprising a step of reacting a carbon-based solid acid with a rare earth metal compound.

[14] The manufacturing method according to

[13] , wherein the metal species of the rare earth metal compound 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.

[15] The method for producing a carbon-based bond according to

[13] or

[14] , wherein the carbon-based solid acid has 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.

[16] The method for producing a carbon-based bond according to any one of

[13] to

[15] , wherein the carbon-based solid acid has a graphene structure at least in part.

[17] A composition comprising a carbon-based bond according to any one of [1] to [6] and a perfluoroacid-based polymer. [Effects of the Invention]

[0012] The carbon-based composite of the present invention has good proton conductivity and electron conductivity, and a polymer electrolyte fuel cell using the carbon-based composite of the present invention in the catalyst layer has excellent power generation characteristics. [Brief explanation of the drawings]

[0013] [Figure 1] Cross-sectional view showing the structure of a polymer electrolyte fuel cell DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to a carbon-based bond having a rare earth metal ion and a carbon-based solid acid bonded to the rare earth metal ion. In this specification, the polymer electrolyte fuel cell may be abbreviated to "fuel cell."

[0015] <Carbon-based solid acid> A carbonaceous solid acid is a carbon material obtained by heat-treating and carbonizing an organic compound, and introducing an anionic moiety such as a sulfonic acid group that fixes a hydrogen ion into the carbon material. Introduction of an anionic moiety such as a sulfonic acid group into the carbon material can be achieved, for example, by heat-treating the organic compound in concentrated sulfuric acid or fuming sulfuric acid, or by sulfonating the carbon material obtained by heat-treating and carbonizing the organic compound using concentrated sulfuric acid or the like.

[0016] The carbon material refers to a material produced by heat-treating an organic compound to carbonize it. Examples of organic compounds that can serve as carbon sources include petroleum pitch, coal-based pitch, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyimide resin, epoxy resin, crystalline cellulose, pure cellulose, trees, plants, fruits, seeds, regenerated cellulose, and aromatic hydrocarbons, with crystalline cellulose, pure cellulose, trees, plants, fruits, seeds, regenerated cellulose, and aromatic hydrocarbons being preferred.

[0017] The carbonaceous solid acid preferably has a graphene structure at least in part. An example of a carbon material having a graphene structure is a graphene sheet. The size of the graphene sheet is not particularly limited, but the maximum length in the plane direction is preferably 1000 nm or less, more preferably 500 nm or less, and more preferably 200 nm or less.

[0018] The carbon-based solid acid preferably has a sulfonic acid group, a hydroxyl group, a carboxyl group, a carbonyl group, a formyl group, an oxysulfonic acid group, or the like as a substituent on the surface of the carbon-based solid acid and on carbon-deficient portions, more preferably a hydroxyl group. Furthermore, the structure on the surface of the carbon-based solid acid and on carbon-deficient portions preferably has a carboxylic acid anhydride structure, a chromene structure, a lactone structure, an ester structure, an ether structure, or the like, more preferably an ether structure. These may be present alone or in combination with one or more other types. The types and abundances of these substituents and structures vary depending on the conditions for carbonization by heat treatment and the carbon source used as the raw material. Note that, in this specification, not all hydrogen atoms in graphene are replaced with the substituents and structures, but graphene has at least hydrogen atoms.

[0019] For example, the non-patent literature Catalyst Preparation Handbook (NTS Corporation (Tokyo), 2011, pp. 634-635) reports that carbon-based solid acids have hydroxyl groups, carboxyl groups, and sulfonic acid groups as substituents on the surface and carbon-deficient portions.

[0020] <Rare earth metal ions> The metal species of the rare earth metal ion is preferably at least one selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, more preferably at least one selected from the group consisting of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, and ytterbium, and even more preferably at least one selected from the group consisting of scandium, yttrium, lanthanum, cerium, samarium, europium, and ytterbium. Rare earth metal ions of these metal species have excellent power generation characteristics.

[0021] The content of rare earth metal ions contained in the carbon-based binder is not particularly limited, but from the viewpoint of power generation characteristics, it is preferably 0.01 to 60 mass % and more preferably 1 to 50 mass % in 100 mass % of the carbon-based binder.

[0022] <Carbon-based bond> In this specification, a carbon-based solid acid containing a rare earth metal ion and a carbon-based solid acid, into which the rare earth metal ion has been introduced in such a manner that the rare earth metal ion is bonded to a substituent or structure possessed by the carbon-based solid acid, is defined as a carbon-based bonded body.

[0023] The rare earth metal ion in the carbon-based bond is preferably present bonded to a monovalent anion formally deprotonated from at least one substituent or structure 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 on the surface of the carbon-based solid acid and in carbon-deficient portions. More preferably, the rare earth metal ion is bonded to a monovalent anion formally deprotonated from at least one substituent or structure selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a lactone structure, and an ester structure. The bonding mode is at least one selected from the group consisting of hydrogen bonding and coordinate bonding. Although hydrogen bonding is assumed to occur via water, if it can be converted to a coordinate bond, stability is excellent, and therefore a coordinate bond is preferred.

[0024] The bond between the carbon-based binder and the rare earth metal ion is preferably in the form of a bond between a monovalent anion formally deprotonated from a hydroxyl group of the carbon-based solid acid and the rare earth metal ion, and more preferably in the form of a chelate structure formed by sandwiching the rare earth metal ion between two monovalent anions derived from hydroxyl groups.

[0025] The carbon-based bond preferably has a structure represented by the following formula (1).

[0026] [ka]

[0027] In formula (1), G represents graphene that may have 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. G is preferably graphene that has at least one selected from the group consisting of a hydroxyl group, a carboxyl group, and a sulfonic acid group.

[0028] A is one group selected from -O-, -COO- and -SO3-, and when there are multiple As, they may be the same or different. A is preferably -O-. B is one group selected from -O-, -COO- and -SO3- or a hydroxyl group, and when there are multiple B's, they may be the same or different. B is preferably -O- or a hydroxyl group, and when there are multiple B's, they may be the same or different. C is one group selected from -O-, -COO- and -SO3- or a hydroxyl group, and when there are multiple C's, they may be the same or different. C is preferably -O- or a hydroxyl group, and when there are multiple C's, they may be the same or different. When B and C are one group selected from -O-, -COO-, and -SO3-, they are each independently bonded to G to which A is bonded, or to G different from G to which A is bonded. When B and C are hydroxyl groups, they are each independently bonded only to Ln. The bonding modes of the bond between A and Ln, the bond between B and Ln, and the bond between C and Ln include hydrogen bonds and coordinate bonds. A preferred bonding mode is when one or more cyclic structures, i.e., chelate structures, are formed between G and Ln via at least two types selected from the group consisting of A, B, and C, because this increases the stability of the bond.

[0029] Ln represents scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium. Ln is preferably scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, or ytterbium, and more preferably a metal ion of scandium, yttrium, lanthanum, cerium, samarium, europium, or ytterbium.

[0030] p is preferably an integer of 1 or more and 18 or less, and more preferably an integer of 4 or more and 10 or less.

[0031] The compound represented by the above formula (1) is not particularly limited, but examples thereof include compounds represented by formula (1a).

[0032] [ka]

[0033] <Method of manufacturing carbon-based binder> The method for producing a carbon-based bond includes a step of reacting a carbon-based solid acid with a rare earth metal compound. The carbon-based bond can be produced by step 1. From the viewpoint of durability, it is preferable to carry out step 2 after step 1.

[0034] [Process 1] In step 1, a carbonaceous solid acid is reacted with a rare earth metal compound. Examples of the carbon-based solid acid include those described above, and it is preferable that the carbon-based solid acid has 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.

[0035] The carbon-based solid acid used in the reaction of step 1 preferably has a graphene structure at least in part. The carbon-based solid acid used in the reaction of step 1 preferably has at least one selected from the group consisting of a hydroxyl group, a sulfonic acid group, and an ether structure.

[0036] The carbon-based solid acid used as a starting material for synthesizing the carbon-based bond of the present invention can be obtained from, for example, Fuji Dye Co., Ltd., Futamura Chemical Co., Ltd., etc. Alternatively, a carbon-based solid acid synthesized by the production method described in patent documents WO 2005 / 029508, Japanese Patent No. 4041409, Japanese Patent No. 4925399, and Japanese Patent No. 5528036 may be used as a starting material.

[0037] The rare earth metal compound used in step 1 is CeBr3, CeCl3·7H2O, CeF3, CeF4, CeI3, DyBr3, DyBr3·xH2O, DyCl3, DyCl3·6H2O, DyF3, DyI3, ErBr3·xH2O, ErCl3, ErCl3·6H2O, ErF3, ErI3, 8 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, 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 CeO2, Dy2O3, Er2O3, Eu2O3, Gd2O3, Ho2O3, La2O3, Lu2O3, Nd2O3, Pr2O3, Pr6O 11 , Sm2O3, Sc2O3, Tb2O3, Tb4O7, Tm2O3, Yb2O3, Y2O3, AlCeO3, (CeO2)(ZrO2) and the like can be mentioned.

[0038] As the rare earth metal compound used in Step 1, 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, and (CeO2)(ZrO2), 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, and Sm2O3 are more preferred. The metal species of the rare earth metal compound used in step 1 is preferably 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.

[0039] A carbon-based bond can be obtained by Step 1. Specifically, a carbon-based bond can be obtained in which a rare earth metal ion is bonded to a monovalent anion formally deprotonated from at least one substituent or structure 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 on the surface and defective portions of a carbon-based solid acid. The bonding mode is at least one selected from a hydrogen bond and a coordinate bond. Preferably, a carbon-based bond can be obtained in which a rare earth metal ion is bonded to a monovalent anion formally deprotonated from at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a lactone structure, and an ester structure. Furthermore, more preferably, for the reason of increased stability, a carbon-based solid bond can be obtained in which the rare earth metal forms one or more ring structures, i.e., chelate structures, with the surface of the carbon-based solid acid via -O-, -COO-, or -SO3-.

[0040] Step 1 can also be carried out in the presence of, for example, 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, etc. Among these, sodium hydride and lithium hydride are preferred.

[0041] The solvent used in step 1 may be a non-aqueous solvent capable of dispersing the carbonaceous solid acid and dissolving or dispersing the rare earth metal compound, such as 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, and 1,4-butane sultone. 1,3-propane sultone is a target of the reaction but can also serve as a solvent. Toluene, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, and 1,3-propane sultone are preferred, with tetrahydrofuran being more preferred.

[0042] The reaction temperature in step 1 is preferably -10 to 200°C, more preferably 0 to 180°C, and even more preferably 10 to 160°C.

[0043] The reaction time in step 1 is not particularly limited, but is preferably 1 to 500 hours, more preferably 2 to 300 hours.

[0044] [Process 2] In step 2, the carbon-based bond obtained in step 1 is washed with acid and water. The carbon-based bond obtained through step 2 is thought to have excellent durability because the washing process removes the substituents on the carbon-based bond that would cause undesired reactions and accelerate device degradation when used in a fuel cell device, minimizing the damage caused by decomposition products to the fuel cell device. The acid used in step 2 may be, for example, an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, sulfurous acid, nitrous acid, or phosphoric acid, or an organic acid such as acetic acid, lactic acid, oxalic acid, citric acid, or formic acid, and from the perspective of a fuel cell device, sulfuric acid is preferred because it leaves fewer impurities behind.

[0045] Step 2 may include a post-hydrolysis washing operation.

[0046] <Composition containing carbon-based binder> The composition containing the carbon-based binder preferably contains a perfluoroacid polymer from the viewpoint of voltage characteristics in a high current range when the composition is used in a catalyst layer of a fuel cell. The composition may contain an electrolyte, a catalyst support, etc., as described below.

[0047] Examples of perfluoroacid polymers include 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 Co., Ltd.), and Aciplex (registered trademark, manufactured by Asahi Kasei Corporation). A composition containing a carbon-based binder is suitably used as a catalyst ink or the like used in the production of a polymer electrolyte fuel cell, which will be described later.

[0048] <Polymer electrolyte fuel cell> FIG. 1 is a cross-sectional view showing a schematic configuration of a polymer electrolyte fuel cell. A polymer electrolyte fuel cell 100 has an anode catalyst layer 103, a cathode catalyst layer 105, and a solid polymer electrolyte membrane 107 sandwiched between the two 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"). In a fuel cell, the MEA is usually sandwiched between separators 109.

[0049] At least one of the anode catalyst layer 103 and the cathode catalyst layer 105 contains the carbon-based bond. Furthermore, the solid polymer electrolyte membrane 107 may also contain the carbon-based bond. From the viewpoint of suppressing an increase in overvoltage during high current driving, it is preferable to use the carbon-based bond in at least the cathode catalyst layer 105.

[0050] The carbon-based composite has proton conductivity, electron conductivity, and gas permeability, and also has the function of supporting a catalyst due to its structure. Therefore, it can be used as a catalyst support, an electrolyte, or both in a catalyst layer of a fuel cell, or as an electrolyte in a solid polymer electrolyte membrane.

[0051] The main functions of the carbon-based binder are that the portion having a sulfonic acid group and the portion bonding the rare earth metal ion with the carbon-based solid acid have a proton conducting function as a solid electrolyte. When the carbon-based binder has a graphene structure, the portion having the graphene structure has an electron conducting function. The solid surface of the carbon-based binder has a function of supporting a catalyst necessary for the fuel cell reaction, and further, the pores of the carbon-based solid acid in the carbon-based binder are thought to have a function of diffusing fuel gas and adsorbing and desorbing water.

[0052] The anode catalyst layer 103 and the cathode catalyst layer 105 each contain a catalyst component, a catalyst support for supporting the catalyst component, and an electrolyte in addition to the carbon-based composite. Alternatively, the catalyst support and the electrolyte may be the carbon-based composite. The carbon-based composite is preferably a type of electrolyte and a type of catalyst support. By using the carbon-based composite as both an electrolyte and a catalyst support, the catalyst support, which has not previously had proton conductivity, can be made proton conductive, which is expected to improve the electrical properties of fuel cells. A catalyst supported on a catalyst carrier is called an electrode catalyst. In this specification, the anode catalyst layer 103 and the cathode catalyst layer 105 may be abbreviated to catalyst layers.

[0053] Any known catalyst can be used as the catalyst component in the anode catalyst layer 103, and any known catalyst can be used as the catalyst component in the cathode catalyst layer 105. Examples of catalyst components used in the anode catalyst layer 103 and the cathode catalyst layer 105 include metals such as platinum, gold, silver, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum, as well as alloys thereof. The main function of the catalyst component is to cause an electrochemical reaction.

[0054] Examples of catalyst supports in the catalyst layer include the carbon-based binders, carbon-based solid acids, carbon blacks such as channel black, furnace black, and thermal black, activated carbons obtained by carbonizing and activating various carbon-containing materials, coke, natural graphite, artificial graphite, and graphitized carbon. Among these, the carbon-based binders, carbon-based solid acids, and carbon black are preferred as catalyst supports because of their high specific surface area and excellent electronic conductivity. The primary function of the catalyst support is to conduct electrons. Another primary function of the catalyst support is the transport of fuel gas and water through the pores in the catalyst support.

[0055] In order to suppress a decrease in the electronic conductivity of the electrode catalyst, a binder that binds the catalyst supports together can be used in the catalyst layer. Examples of binders include fluorine-based sulfonic 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 Co., Ltd.), and Aciplex (registered trademark, manufactured by Asahi Kasei Corporation).

[0056] Examples of the electrolyte in the catalyst layer include the carbon-based binder, carbon-based solid acid, fluorine-based sulfonic acid polymers (perfluoro acid polymers) such as Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay Chemical Industries, Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), hydrocarbon-based sulfonic acid polymers, and partially fluorinated hydrocarbon-based sulfonic acid polymers. The electrolyte is preferably the carbon-based binder, carbon-based solid acid, Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay Chemical Industries, Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), or Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), with the carbon-based binder and Nafion (registered trademark, manufactured by DuPont Chemical Industries, Ltd.) being more preferred. The carbon-based binder can be used alone as the electrolyte, or the carbon-based binder can be used in combination with the above-mentioned electrolyte. Although the main function of the electrolyte in the catalyst layer is to conduct protons, since it is also required to pass fuel gas and transport water at the same time, the electrolyte in the catalyst layer of the present invention preferably contains a perfluoroacid polymer such as Nafion, in addition to the carbon-based binder, from the viewpoint of voltage characteristics in a high current region. The catalyst layer containing the carbon-based binder can be made of any of the materials for the solid polymer electrolyte membrane, namely, a fluorine-based sulfonic acid polymer, a hydrocarbon-based sulfonic acid polymer, and a partially fluorinated hydrocarbon-based sulfonic acid polymer, and it is preferable to use a fluorine-based sulfonic acid polymer or a partially fluorinated hydrocarbon-based sulfonic acid polymer.

[0057] The method for producing catalyst layer 103 and catalyst layer 105 will be described. A catalyst ink is prepared by dispersing a catalyst component, a catalyst carrier, and an electrolyte in a solvent, and then the catalyst ink is applied to a target substrate and dried to produce a catalyst layer. Examples of the target substrate include a solid polymer electrolyte membrane, GDL, and a sheet made of fluororesin, and the catalyst layer can be produced by a known production method. When the catalyst ink is applied to a sheet made of fluororesin, the applied catalyst layer is transferred to the solid electrolyte. A sheet made of polytetrafluoroethylene (PTFE) is commonly used as the fluororesin sheet.

[0058] The catalyst ink generally comprises the catalyst component, the catalyst carrier for supporting the catalyst component, the electrolyte, and a solvent. The catalyst ink may also contain a binder for binding the catalyst carriers together. Adjusting the catalyst ink composition can improve functions and performance, such as suppressing a decrease in electronic conductivity, improving proton conductivity, improving fuel gas diffusibility, improving water transport efficiency, and improving the mechanical strength of the catalyst layer.

[0059] Examples of solvents used in the catalyst ink include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, pentanol, dimethyl sulfoxide, and N,N-dimethylformamide. Water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and isobutyl alcohol are preferred. Two or more of the above-mentioned solvents can also be mixed and used. From the viewpoints of preventing ink re-aggregation and facilitating application, as well as preventing solvent residue in the catalyst layer, water, ethanol, 1-propanol, and 2-propanol are more preferred as solvents used in the catalyst ink.

[0060] Examples of the catalyst ink composition include a catalyst ink composition in which the catalyst is platinum, the catalyst support is carbon black, and the electrolyte is the carbon-based binder and Nafion (registered trademark, manufactured by DuPont Co.), and a catalyst ink composition in which the catalyst is platinum, the catalyst support is carbon black, and the electrolyte is the carbon-based binder. Further examples include a catalyst ink composition in which the catalyst is platinum, the catalyst support is carbon black and the carbon-based binder, or the carbon-based binder alone, and the electrolyte is the carbon-based binder. Thus, a catalyst ink in which at least a portion of the catalyst support is the carbon-based binder is produced by subjecting a catalyst layer-forming composition containing the carbon-based binder and a catalyst to a crushing treatment, thereby obtaining a catalyst ink containing a carbon-based binder supporting a catalyst.

[0061] Examples of the crushing treatment include dry crushing treatment and wet crushing treatment. Examples of dry crushing treatment include a ball mill, a planetary mill, a pin mill, and a jet mill. Examples of wet crushing treatment include an ultrasonic homogenizer, an ultrasonic disperser, a bead mill, a sand grinder, a homogenizer, and a wet jet mill. Among these, preferred crushing treatments are a ball mill, an ultrasonic homogenizer, an ultrasonic disperser, and a homogenizer, with the ultrasonic homogenizer and the ultrasonic disperser being particularly preferred. There are no particular limitations on the solvent used in the wet crushing treatment, and the solvent used in the catalyst ink can be used.

[0062] The carbon-based binder is used in preparing the catalyst ink to produce a membrane electrode assembly (MEA), which is then incorporated into a single cell, thereby achieving power generation properties.

[0063] The proportion of the carbon-based binder used in the catalyst layer is calculated using the following formula. In the following calculation formula, the weights of the electrode catalyst, carbon-based binder, electrolyte, and binder are calculated as solid weights minus the weights of water and solvent. In the following calculation formula, the electrolyte and electrode catalyst do not include the carbon-based binder of the present invention.

[0064] Carbon-based binder ratio (wt%) = [carbon-based binder (weight) / [total weight in catalyst layer (solid weight)]] × 100 (weight %) = [carbon-based binder (weight) / [electrode catalyst (weight) + electrolyte (weight) + binder (weight) + carbon-based binder (weight)]] × 100 (weight%) The proportion of carbon-based bonds is preferably 1 to 95%, more preferably 5 to 40%.

[0065] Examples of materials for the solid polymer electrolyte membrane 107 include the carbon-based binder, 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 Co., Ltd.), and Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), hydrocarbon-based sulfonic acid polymers, and partially fluorinated hydrocarbon-based sulfonic acid polymers.

[0066] The gas diffusion layer 101 is not particularly limited, but a conductive porous material is preferably used. Examples of such materials include carbonaceous paper and nonwoven fabric, felt, and nonwoven fabric. Furthermore, some GDLs are coated with a layer called a microporous layer (hereinafter abbreviated as "MPL"), which is a coating layer primarily composed of a water-repellent resin and a carbon material. It has been reported that this layer effectively transports water during power generation in fuel cells. A gas diffusion layer having this MPL can also be used as a catalyst layer containing the carbon-based binder. In the power generation tests of the present invention, water-repellent carbon paper, which is a GDL having this MPL, was used. [Example]

[0067] Examples and test examples of the present invention will be described in more detail below, but the present invention is not limited to these.

[0068] <Solid polymer fuel cell power generation test A> The fabricated MEA was placed in a 1cm 2After incorporating it into a single cell (JARI standard cell, manufactured by FC Development Co., Ltd.) with an electrode area of 1000mV, a power generation test of the fuel cell was carried out. Evaluation was carried out using a fuel cell evaluation system (AutoPEM, manufactured by Toyo Corporation) at a temperature of 80°C, a relative humidity of 95%, and a hydrogen gas flow of 1 L / min and an air gas flow of 2 L / min, and the current density and voltage were measured.

[0069] <Preparation Example 1: Preparation of carbon-based solid acid> A wet carbon-based solid acid (manufactured by Futamura Chemical Co., Ltd., Taiko Solid Acid, brand name "CP for high temperatures") (10 g, solid content 37.3%) was added to an eggplant flask, placed in an evaporator connected to a vacuum pump, and dried at a bath temperature of 90°C until a constant weight was reached, thereby obtaining a dried carbon-based solid acid (3.5 g). Example 1: Synthesis of carbon-based bond (1) The carbonaceous solid acid (779.8 mg) obtained in Preparation Example 1 and samarium(II) iodide (1.0 g, 2.47 mmol) dissolved in tetrahydrofuran (25 mL) were sequentially added to a reaction vessel. Next, sodium hydride powder (333.0 mg, 13.9 mmol) was added in portions to the reaction vessel. The reaction mixture was placed in an oil bath set at 66°C and stirred for 12 hours. After the reaction was completed, the temperature was returned to room temperature (20-25°C), and then 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, the reaction mixture was filtered using a vacuum filter equipped with silica filter paper and washed with 2 mol / L sulfuric acid (10 mL). Next, the filtrate was washed with ion-exchanged water until the hydrogen ion exponent (pH) of the filtrate became neutral. This crude material was added to a recovery flask, which was then placed in an evaporator connected to a vacuum pump and dried at a bath temperature of 90°C until a constant weight was reached, yielding carbon-based bond (1) as a black solid (641.4 mg). ICP emission spectroscopy confirmed that carbon-based bond (1) contained 0.5 wt% samarium.

[0070] <Example 2: Synthesis of carbon-based bond (2)> The dried carbonaceous solid acid (0.919 mg) obtained in Preparation Example 1 and cerium(III) nitrate hexahydrate (4.852 g, 11.17 mmol) dissolved in tetrahydrofuran (15 g) were sequentially added to a reaction vessel. Next, sodium hydride powder (678.7 mg, 28.3 mmol) was added in portions to the reaction vessel. The reaction mixture was placed in an oil bath set at 66°C and stirred for 12 hours. After the reaction was completed, the temperature was returned to room temperature (20-25°C), and then ion-exchanged water (20 mL) and 2 mol / L sulfuric acid (40 mL) were added to the reaction vessel in this order and stirred for 1 hour. Next, the reaction mixture was filtered using a vacuum filter equipped with silica filter paper and washed with 2 mol / L sulfuric acid (20 mL). Next, the filtrate was washed with ion-exchanged water until the pH became neutral. This crude material was added to a recovery flask, which was then placed in an evaporator connected to a vacuum pump and dried at a bath temperature of 90°C until a constant weight was reached, yielding carbon-based binder (2) as a black solid (1.569 g). Thermogravimetry was used to calculate that carbon-based binder (2) contained 28.7 wt% cerium.

[0071] <Test Example 1> The carbon-based aggregate (1) was added to an eggplant flask, and then placed in an evaporator connected to a vacuum pump, and dried to a constant weight at a bath temperature of 90 to 100° C. Alternatively, the carbon-based aggregate was placed in a vacuum dryer, and then connected to a vacuum pump and dried at a temperature of 90 to 120° C. to a constant weight.

[0072] The catalyst ink was prepared using a platinum-supported carbon electrode catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., platinum content: 46.5 wt%, product name "TEC10E50E"), dried carbon-based binder (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.). Specifically, the electrode catalyst, carbon-based binder (1), Nafion dispersion solution, and 2-propanol were added to a glass vial in this order, and the dispersion solution was subjected to ultrasonic irradiation for 30 minutes using an AS ONE Corporation ultrasonic cleaner ASU-6 with the oscillation power set to high to prepare the catalyst ink. The conditions for preparing the catalyst ink are described below.

[0073] Catalyst ink preparation conditions: Nafion ratio (wt%) = [Nafion solid content (weight) / [electrode catalyst (weight) + Nafion solid content (weight) + carbon-based binder (weight)]] × 100 (weight%) was set to 29% by weight. Percentage of carbon-based binders (wt%) = [carbon-based binder (weight) / electrode catalyst (weight) + Nafion solid content (weight) + carbon-based binder (weight)] × 100 (weight%) The catalyst ink was prepared with a concentration of 16 wt%. Specifically, for an electrode catalyst weight of 27.4 mg, the catalyst ink was prepared with a Nafion dispersion solution (294.8 mg), carbon-based binder (8.0 mg), and 2-propanol (1 mL). The Nafion dispersion solution (294.8 mg) corresponds to a Nafion solid content (14.7 mg).

[0074] Catalyst ink application conditions: The catalyst ink was applied using a stage and applicator (made by Nissan Chemical Industries, Ltd.) with a target of a Teflon sheet with an area of 8 cm x 8 cm and a thickness of 130 μm. The entire amount of the prepared catalyst ink was used to apply the ink to a 1 cm 2A decal with a catalyst layer of 0.2 mg of platinum per unit area was created on a Teflon sheet and cut into 1 cm x 1 cm decals to be used as decals for the anode and cathode catalyst layers. The platinum weight of the anode and cathode was confirmed to be 0.2 mg based on the weight difference between the decal and the decal after transfer.

[0075] Steps for preparing an MEA: The membrane electrode assembly (MEA) was fabricated using a solid polymer electrolyte membrane, a gas diffusion layer (GDL), and a decal using catalyst ink. The GDL was made of carbon paper with MPL (product name "28BC" manufactured by SGL Carbon Japan Co., Ltd.). A 5cm x 5cm square Nafion 212 membrane (registered trademark, manufactured by DuPont, purchased from Toyo Corporation, membrane thickness: 50μm) was cut and placed in the center as a solid polymer electrolyte membrane. Decals (area 1cm x 1cm) with catalyst layers on Teflon sheets were then placed on both sides of the solid polymer electrolyte membrane. The resulting membrane was then thermocompressed at a platen temperature of 132°C, a load of 0.6kN, and a compression time of 40 seconds. The Teflon sheets were then peeled off to produce a catalyst-coated membrane (CCM). The platinum weights of the anode and cathode were determined by the weight difference between the decal and the decal after transfer. The GDL was made of carbon paper (manufactured by SGL Carbon Japan Co., Ltd., product name "28BC", area 1cm x 1cm) and was stacked on both the anode and cathode sides with the MPL layer side facing the solid polymer electrolyte membrane.The JARI standard cell was then tightened with a torque wrench in 1Nm increments up to 4Nm to press the GDL and CCM together. Using the fabricated MEA, a power generation test A of the polymer electrolyte fuel cell was carried out. The results of voltage and current density are shown in Table 1.

[0076] <Comparative Test Example 1> An MEA was prepared in the same manner as in Test Example 1, except that 8.0 mg of a carbon-based solid acid (manufactured by Futamura Chemical Co., Ltd., Taiko Solid Acid, brand "CP High Temperature") was used in preparing the catalyst ink instead of the carbon-based binder (1). A power generation test A of a polymer electrolyte fuel cell was performed using the prepared MEA. The voltage and current density results are shown in Table 1.

[0077] <Test Example 2> An MEA was prepared in the same manner as in Test Example 1, except that 8.0 mg of carbon-based binder (2) was used in the preparation of the catalyst ink instead of carbon-based binder (1). Using the prepared MEA, a power generation test A of a polymer electrolyte fuel cell was carried out. The results of voltage and current density are shown in Table 1.

[0078] <Test Example 3> An MEA was fabricated in the same manner as in Test Example 1, except that a Nafion 211 membrane (registered trademark, manufactured by DuPont Co., Ltd., purchased from Chemix Corporation, membrane thickness: 25 μm) was used as the solid polymer electrolyte membrane instead of a Nafion 212 membrane (registered trademark, manufactured by DuPont Co., Ltd., membrane thickness: 50 μm). A fuel cell power generation test A was carried out using the fabricated MEA. The voltage and current density results are shown in Table 1.

[0079] <Test Example 4> An MEA was fabricated in the same manner as in Test Example 2, except that a Nafion 211 membrane (registered trademark, manufactured by DuPont, membrane thickness: 25 μm) was used as the solid polymer electrolyte membrane instead of a Nafion 212 membrane (registered trademark, manufactured by DuPont, membrane thickness: 50 μm). A fuel cell power generation test A was carried out using the fabricated MEA. The voltage and current density results are shown in Table 1.

[0080] [Table 1]

[0081] When the power generation characteristics of Test Example 1 and Comparative Test Example 1, which were conducted under the same conditions in a power generation test of a polymer electrolyte fuel cell except for the type of test sample, were compared, Test Example 1, which used the carbon-based binder of Example 1, showed better results, and the carbon-based binder containing rare earth metal ions showed improved power generation characteristics compared to the carbon-based solid acid. When the power generation characteristics of Test Example 2 and Comparative Test Example 1, which were performed under the same conditions in a power generation test of a polymer electrolyte fuel cell except for the type of test sample, were compared, Test Example 2, which used the carbon-based binder of Example 2, showed better results, and the carbon-based binder containing rare earth metal ions showed improved power generation characteristics compared to the carbon-based solid acid. In a comparison between Test Example 1 and Test Example 3, and between Test Example 2 and Test Example 4, both of which used the same carbon-based binder, it was found that when the solid polymer electrolyte membrane was thin, the proton conductivity was improved compared to when the membrane was thick, and therefore the power generation characteristics were improved. Furthermore, the difference from Comparative Test Example 1, which used a carbon-based solid acid, was larger in Test Examples 3 and 4 than in Test Examples 1 and 2. [Industrial Applicability]

[0082] The carbon-based composite of the present invention is useful, for example, as an electrolyte material for a polymer electrolyte fuel cell (e.g., an electrolyte material used in a catalyst layer, a solid polymer electrolyte membrane, a catalyst support, etc.), and is expected to improve the power generation characteristics and durability of the polymer electrolyte fuel cell. [Explanation of symbols]

[0083] 100 Polymer electrolyte fuel cell 101 Gas diffusion layer 103 Anode catalyst layer 105 Cathode catalyst layer 107 Solid polymer electrolyte membrane 109 Separator

Claims

1. rare earth metal ions, A carbon-based bonded body having a rare earth metal ion and a carbon-based solid acid bonded thereto, A carbon-based bond, wherein the metal species of the rare earth metal ion is at least one selected from the group consisting of scandium, yttrium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

2. The carbon-based bond according to claim 1 , wherein the carbon-based solid acid has a graphene structure at least in part.

3. 3. The carbon-based bond according to claim 1 or 2, wherein the carbon-based solid acid has 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.

4. The carbon-based bond according to any one of claims 1 to 3, wherein the rare earth metal ion is bonded to a formally deprotonated monovalent anion via at least one substituent or structure 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 of the carbon-based solid acid.

5. The carbon-based bond according to any one of claims 1 to 4, having a structure represented by the following formula (1): 【Chemical 1】 (In formula (1), G represents graphene which may have at least one structure 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; Ln represents a metal ion of scandium, yttrium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium; A is —O—, —COO—, or —SO ３ - is one selected from, and when there are multiple A's, they may be the same or different, B is —O—, —COO—, or —SO ３ - or a hydroxyl group, and when there are two or more B's, they may be the same or different, C is —O—, —COO—, or —SO ３ - or a hydroxyl group, and when there are multiple C's, they may be the same or different, B and C are —O—, —COO— and —SO ３ -, each independently bonded to a G to which A is bonded or to a G that is different from the G to which A is bonded; When B and C are hydroxyl groups, they are each independently bonded only to Ln; p represents an integer of 1 or more and 18 or less.

6. A catalyst layer of a polymer electrolyte fuel cell, comprising the carbon-based composite according to any one of claims 1 to 5.

7. 7. The catalyst layer of a polymer electrolyte fuel cell according to claim 6, wherein the carbon-based binder is a type of electrolyte and a type of catalyst support.

8. 8. The catalyst layer of a polymer electrolyte fuel cell according to claim 6, further comprising a perfluoroacid polymer.

9. The catalyst layer for a polymer electrolyte fuel cell according to any one of claims 6 to 8, further comprising a binder.

10. A membrane electrode assembly comprising a solid polymer electrolyte membrane, a gas diffusion layer, and the catalyst layer according to any one of claims 6 to 9.

11. A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 10.

12. [Step 1] A step of reacting a carbon-based solid acid with a rare earth metal compound to obtain a carbon-based bond; [Step 2] Washing the carbon-based bond obtained in step 1 with acid and water. A method for producing a carbon-based bond, comprising:

13. The method for producing a carbon-based bond according to claim 12, wherein the metal species of the rare earth metal compound 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.

14. The method for producing a carbon-based bond according to claim 12 or 13, wherein the carbon-based solid acid has 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.

15. The method for producing a carbon-based bond according to any one of claims 12 to 14, wherein the carbon-based solid acid has a graphene structure at least in part.

16. A composition comprising the carbon-based conjugate according to any one of claims 1 to 5 and a perfluoroacid-based polymer.

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