Non-precious metal-based catalyst and method for producing it

Abstract

A non-precious metal-based catalyst for a fuel cell electrode, comprising: a porous carbon with a first pore (H1) and a second pore (H2) that is smaller than the first pore (H1), wherein the first pore (H1) has a pore size of 5 to 100 nm and an active site (A) of the non-precious metal-based catalyst is selectively attached only to an inner wall of the first pore (H1), wherein the active site (A) of the non-precious metal-based catalyst is formed by a precursor of the non-precious metal-based catalyst (CP), and wherein the precursor of the non-precious metal-based catalyst (CP) has a form in which at least one of phthalocyanine, phthalocyanine tetrasulfonate, octabutoxyphthalocyanine, hexadecafluorophthalocyanine, octakis-octyloxyphthalocyanine, tetra-tert-butylphthalocyanine, tetraazaphthalocyanine, tetraphenoxyphthalocyanine, tetra-tert-butyl-tetrakis-dimethylaminophthalocyanine, tetrakiscumylphenoxyphthalocyanine, tetrakis-pyridiniomethylphthalocyanine, tetranitrophthalocyanine, naphthalocyanine, tetra-tert-butyl-naphthalocyanine, tetraphenylporphine, tetrakis-pentafluorophenylporphyrin, tetrakis-methylpyridinioporphyrin-tetratoluenesulfonate, tetrakistrimethylammoniophenylporphyrin-tetratoluenesulfonate, Tetramethyl-divinyl-porphine dipropionic acid, tetrapyridylporphine, octaethylporphyrin, tetrakis-methoxyphenyl-porphine, tetraphenylporphine-tetracarboxylic acid, tetrakis-hydroxyphenyl-porphine, tetrakis-sulfonatophenyl-porphine, etioporphyrin, 1,10-phenanthroline, 1,10-phenanthroline-5,6-dionedimethyl-1,10-phenanthrolin, 1,10-Phenanthrolin-5,6-dion, Dimethyl-1,10-phenanthrolin, Dimethoxy-1,10-phenanthrolin, Methoxy-1,10-phenanthrolin, Amino-1,10-phenanthrolin, Methyl-1,10-phenanthrolin, Dihydroxy-1,10-phenanthrolin, Tetramethyl-1,10-phenanthrolin, Chlor-1,10-phenanthrolin, Dichlor-1,10-phenanthrolin, Nitro-1,10-phenanthrolin, Brom-1,10-phenanthrolin, Tetrabrom-1,10-phenanthrolin, Pyrazino[1,10]phenanthrolin, Diphenyl-1,10-phenanthrolin, Dimethyl-diphenyl-1,10-phenanthrolin, Ethenyl-formyl(hydroxy-trimethyltetradecyl)-trimethyl-porphin-dipropanoat, Diethenyl-tetramethyl-porphin-dipropanoat, Bis((amino-carboxyethyl)thio)ethyl-tetramethyl-porphin-dipropanoat, Dihydro-dihydroxy-tetramethyl-divinyl-porphindipropionsäurelactonat, Ethenyl(hydroxyl-trimethyl-tetradecatrienyl)-tetramethyl-porphin-dipropanoat, Carboxyethenyl-carboxyethyl-dihydro-bis(hydroxymethyl)-tetramethyl-porphin-dicarboxylat, (Dimethylbenzimidazolyl)cyanocobamid, Curtis-Makrocyclus,The Jäger macrocycle and the DOTA macrocycle are coordinated on a metal.

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a non-precious metal-based catalyst used as an electrode material for fuel cells and to a method for producing the same. Description of related technology

[0002] In conventional proton exchange membrane fuel cells (PEMFCs), a precious metal with high catalytic activity and high potential, especially platinum, largely containing fine particles, has been used as a main component as an electrode catalyst.

[0003] However, since platinum is a rare and expensive metal, the need is increasing to develop an alternative non-precious metal-based catalyst for oxygen reduction reactions of fuel cells that has high activity and can replace platinum catalysts.

[0004] A method was investigated to use an additive such as zirconium oxide to reduce platinum usage. A fabrication process for a transition metal oxynitride electrode catalyst was reported, involving the sputtering of a transition metal oxynitride onto the surface of a support material.

[0005] However, currently available non-precious metal-based electrode catalysts exhibit insufficient catalytic activity, so the performance of fuel cells that have the same can be improved.

[0006] The information disclosed in this section of the background of the invention is intended only to improve the understanding of the general background of the invention and should not be interpreted as confirmation of or any form of suggestion that this information constitutes prior art known to a person skilled in the art.

[0007] For example, US 2009 / 0098442A1 discloses a non-precious metal-based catalyst for a fuel cell electrode, comprising a porous carbon with first and second pores that are smaller than the first pores, the first pores having a pore size of 5 to 100 nm and active sites of the non-precious metal-based catalyst being formed at pores in the size range greater than 2 nm.

[0008] Other non-precious metal-based catalysts are known, for example, from DE 10 2005 033 938 A1, DE 101 32 490 A1 and US 2017 / 0263 941 A1. Brief explanation of the invention

[0009] Several aspects of the present invention are aimed at providing a non-precious metal-based catalyst with a catalytically active site selectively positioned on the surfaces of micropores, and a method for producing the same. According to an exemplary embodiment of the present invention, the types of precursors / precursors of non-precious metal-based catalysts used for producing the catalysts and the process parameters for this can be controlled.

[0010] The present invention provides a non-precious metal-based catalyst with the features according to claim 1 and a method for producing a non-precious metal-based catalyst with the features according to claim 7. Further embodiments of the catalyst and the production method are described in the respective dependent claims.

[0011] According to one aspect of the present invention, a non-precious metal-based catalyst is provided for an electrode of a fuel cell. The non-precious metal-based catalyst comprises a porous carbon with a first pore and a second pore that is smaller than the first pore, wherein the first pore has a pore size of about 5 to 100 nm (e.g., about 5 nm, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or about 100 nm) and has an inner wall into which an active site of the non-precious metal-based catalyst is incorporated.

[0012] The porous carbon can have a structure in which the first pore and the second pore are uniformly connected in three-dimensional space.

[0013] The first pore can have a pore size of approximately 15 to 60 nm (e.g., approximately 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or approximately 60 nm).

[0014] The metal may contain at least one transition metal selected from iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni) and chromium (Cr).

[0015] The precursor of the non-precious metal-based catalyst can be a transition metal with a weight (e.g., mass) / proportion of approximately 1 to 50 wt% (e.g., approximately 1 wt%, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or approximately 50% by weight based on the total weight (e.g., total mass) of the porous carbon (The proportion can be, for example, the ratio of the weight of the transition metal to the total weight of the porous carbon, or the proportion can be, for example, the ratio of the weight of the transition metal to the sum of the total weight of the porous carbon and the weight of the transition metal / precursor).

[0016] The porous carbon may have an anchor point inserted into or attached to the surface of a pore of the porous carbon to increase interactions between the porous carbon and the precursor of the non-precious metal-based catalyst.

[0017] According to a further aspect of the present invention, a method for producing a non-precious metal-based catalyst for a fuel cell electrode is provided. The method comprises mixing a porous carbon with a precursor of a non-precious metal-based catalyst; heat-treating the mixture at a temperature of about 600 to 1200°C (e.g., about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C, or about 1200°C); stirring the heat-treated mixture in an acidic solution; and washing and drying the stirred mixture.

[0018] The first pore can have a pore size of 15 to 60 nm (e.g., approximately 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or approximately 60 nm).

[0019] The process may further include heat treatment of a solid powder obtained after or by drying in an ammonia (NH3) gas atmosphere at a temperature of about 600°C to about 1200°C (e.g. about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C or about 1200°C) for about 5 to 60 minutes (e.g. about 5 minutes, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or about 60 minutes).

[0020] The process may further include the formation of an anchoring point on the surface of a pore of the porous carbon by heat treatment of the porous carbon in an ammonia (NH3) gas atmosphere at a temperature of about 600°C to about 1200°C (e.g. about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1100°C or about 1200°C) for about 5 to 60 minutes (e.g. about 5 minutes, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or about 60 minutes).

[0021] The metal may contain at least one transition metal selected from iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni) and chromium (Cr).

[0022] The precursor of the non-precious metal-based catalyst can contain a transition metal with a weight of 1 to 50 wt% based on the total weight of the porous carbon when the porous carbon is mixed with the precursor of the non-precious metal-based catalyst.

[0023] The heat treatment of the mixture at a temperature of 600 to 1200°C can involve heat treatment of the mixture in an inert gas atmosphere at a temperature of 600 to 1200°C for 10 to 300 minutes.

[0024] Stirring the heat-treated mixture in an acidic solution can involve adding the heat-treated mixture to an acidic solution with a concentration of 0.1 M or greater and stirring the resulting mixture. Brief description of the drawings Fig. Figure 1 is a schematic cross-sectional view of a non-precious metal-based catalyst for electrodes of a fuel cell according to one embodiment. Fig. Figure 2 is an exploded view or enlarged view of part A of Fig. 1. Fig. Figure 3 is a transmission electron microscopy (TEM) image of a structure of MSUFC porous carbon. Fig. Figure 4 is a figure illustrating the pore size distribution of micropores of MSUFC porous carbon. Fig. Figure 5 is a figure illustrating the pore size distribution of ultrafine pores of MSUFC porous carbon. Fig. Figure 6 is a TEM image of the structure of a final non-precious metal-based catalyst. Fig. Figure 7 is a figure illustrating the pore size distribution of micropores of the non-precious metal-based catalyst. Fig. Figure 8 is a diagram that schematically illustrates a reaction taking place on the surface of a pore of porous carbon, into which an anchor point has not been introduced. Fig. Figure 9 is a diagram that schematically illustrates a reaction taking place on the surface of a pore of porous carbon into which an anchor point is inserted. Fig. Figure 10 is a schematic diagram illustrating a process for producing a non-precious metal-based catalyst according to one embodiment. Fig. Figure 11 is a flowchart describing the process for producing the non-precious metal-based catalyst. Fig. Figure 12 is a graph illustrating results of the oxygen reduction reaction (ORR) in relation to the types of precursors of the non-noble metal-based catalyst. Fig. Figure 13 is a graph illustrating oxygen reduction reaction (ORR) results depending on the introduction of anchor sites. Fig. Figure 14 is a graph illustrating results of ORR in relation to heat treatment conditions. Fig. 15 and Fig. 16 are graphs that illustrate Koutecky-Levich representations / plots. Fig. Figure 17 is a graph illustrating changes in the performance of individual cells with respect to the spraying method. Fig. Figure 18 is a graph illustrating changes in the performance of individual cells with respect to the mass ratio of the Nafion ionomer to the non-precious metal-based catalyst added to the catalyst solution. Fig. Figure 19 is a graph illustrating changes in the performance of individual cells in relation to the amount of catalyst loaded. Fig. Figure 20 is a graph illustrating the results of durability tests of individual cells. Fig. Figure 21 is a diagram illustrating reactions of reactants in relation to the positions of catalytically active sites. Fig. 22 and Fig. Figure 23 are graphs illustrating ORR results and changes in the performance of individual cells in relation to the positions of the catalytically active sites.

[0025] It should be understood that the attached drawings are not necessarily to scale and represent a somewhat simplified depiction of various features that explain the basic principles of the invention. The specific design features of the present invention as disclosed herein, e.g., having specific dimensions, orientations, positions, and shapes, are partly determined by the specific intended application and environment of use.

[0026] In the figures, reference numerals across the different figures of the drawing refer to the same or equivalent parts of the present invention. Detailed description

[0027] Furthermore, it should be understood that the terms “include” or “have” are intended to indicate the existence of elements disclosed in the specifications and not to exclude the possibility that one or more further elements may exist or be added.

[0028] In this description, the terms "first", "second", etc. are used to distinguish one component from other components; therefore, the components are not limited by these terms.

[0029] An expression used in the singular includes the expression in the plural, unless it has a clearly different meaning in the context.

[0030] The reference symbols used in operations / for steps are used for easier description and are not intended to describe the sequence of operations, and the operations may be performed in a different order unless otherwise stated.

[0031] The present invention relates to a nanoporous non-precious metal-based catalyst having a uniform structure and a method for producing the same.

[0032] The non-precious metal-based catalyst according to an exemplary embodiment of the present invention is used in oxygen reduction reactions that take place in the cathodes of proton exchange membrane fuel cells (PEMFCs). The non-precious metal-based catalyst can be provided by doping / incorporating a precursor of the non-precious metal-based catalyst into a carbon composite structure with macropores on its surface. Therefore, the manufacturing costs can be reduced compared to conventional platinum catalysts, and the non-precious metal-based catalyst with several tens of nanoscale pores can reduce the mass transfer resistance in a membrane electrode assembly (MEA).

[0033] The structure of the non-precious metal-based catalyst for fuel cell electrodes according to an exemplary embodiment is described below, and then the method for manufacturing it is described.

[0034] Fig. Figure 1 is a schematic cross-sectional view of a non-precious metal-based catalyst for fuel cell electrodes according to one embodiment. Fig. Figure 2 is an enlarged representation of part A of Fig. 1.

[0035] Referring to the illustrations Fig. 1 and Fig. 2. The non-precious metal-based catalyst for fuel cell electrodes has a structure in which active sites of the non-precious metal-based catalyst are / are introduced into the inner walls of pores of porous carbon.

[0036] While a platinum catalyst used in conventional fuel cell electrodes is loaded onto the surface of carbon, the non-precious metal-based catalyst, according to an exemplary embodiment, is formed by doping the precursor of the non-precious metal-based catalyst into the porous carbon structure, in other words, by introducing the precursor of the non-precious metal-based catalyst into a carbon network structure of the porous carbon.

[0037] Porous carbon can be a porous carbon material with pores. The pores on the surface of the porous carbon can include primary pores and secondary pores, which are smaller than the primary pores. In particular, the first pores of the porous carbon can have a pore size of about 5 to 100 nm (e.g., about 5 nm, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or about 100 nm), preferably 15 to 50 nm (e.g., about 5 nm, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, The first pores have a pore size of 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or approximately 50 nm). The second pores can have a pore size of several nm, which is the smallest pore size obtainable during the production of porous carbon. Within this description, the first pores can be referred to as micropores, and the second pores can be referred to as ultrafine pores.

[0038] The first and second pores can form a uniformly connected structure in three-dimensional space. The structure of the porous carbon and pore size distribution data based on the MSUFC porous carbon used herein are described below.

[0039] Fig. Figure 3 is a transmission electron microscopy (TEM) image of a structure of MSUFC porous carbon. Fig. Figure 4 is a figure illustrating the pore size distribution of micropores of MSUFC porous carbon. Fig. Figure 5 is a figure illustrating the pore size distribution of ultrafine pores of MSUFC porous carbon.

[0040] Referring to the illustrations Fig. 3 and Fig. 4. It is confirmed that micropores with a pore size of approximately 15 to approximately 60 nm are formed on / at the surface of the MSUFC porous carbon, and a channel with a size of approximately 2 to approximately 10 nm is formed within it. Furthermore, with reference to the figures Fig. 3 and Fig. 5, it is confirmed that ultrafine pores with a pore size of about 0.5 to about 1.5 nm are formed on / at the surface of the MSUFC porous carbon.

[0041] Generally, if the pore size of the porous carbon is smaller than 15 nm, the mass transport resistance can increase. If the pore size of the porous carbon is larger than 60 nm, the specific surface area of ​​the porous carbon can decrease. Therefore, the first pores can have a size of approximately 5 to 100 nm (e.g., approximately 5 nm, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or approximately 100 nm), preferably 5 to 60 nm (e.g., approximately 5 nm, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or about 60 nm), according to an exemplary embodiment, be incorporated into the carbon structure to obtain satisfactory mass transfer resistance and a satisfactory specific surface area.

[0042] Active sites of the non-precious metal-based catalyst are located on the inner walls of the first pores of the porous carbon, as in Fig. Figure 3 illustrates the formation of active sites of the non-precious metal-based catalyst. The active sites can be formed by using a precursor of the non-precious metal-based catalyst. According to the present embodiment, a precursor of the non-precious metal-based catalyst with a diameter smaller than that of the first pores and larger than that of the second pores can be used to control the conditions of the manufacturing process, such that the active sites of the non-precious metal-based catalyst are selectively formed on the surfaces of the first pores.

[0043] For example, if iron phthalocyanine with a diameter of approximately 1.2 nm is used as a precursor of the non-noble metal-based catalyst, most of the second pores are smaller than the precursor of the non-noble metal-based catalyst. Therefore, almost all precursors of the non-noble metal-based catalyst can interact with the surfaces of the first pores to selectively form the catalytically active sites on the inner walls of the first pores. Meanwhile, since the porous carbon channel, as described above, has a size of approximately 2 to 10 nm, the catalytically active sites can also be formed on sections of the inner walls of the channel.

[0044] Fig. Figure 6 is a TEM image of the structure of a final non-precious metal-based catalyst. Fig. Figure 7 illustrates the pore size distribution of micropores in the non-precious metal-based catalyst. Fig. 6 and Fig. Figure 7 illustrates results of experiments in the case where iron phthalocyanine is used as a precursor of the non-noble metal-based catalyst.

[0045] The illustrations Fig. 6 and Fig. The results shown in 7 are compared with those in the figures. Fig. 3 and Fig. The results were compared to those shown in Figure 4. In the case of the non-precious metal-based catalyst according to an exemplary embodiment, in which the porous carbon is doped with the precursor of the non-precious metal-based catalyst, it can be confirmed that the pore distribution decreases after doping the porous carbon with the precursor of the non-precious metal-based catalyst. Therefore, it can be confirmed that the precursor of the non-precious metal-based catalyst is doped into the surfaces of the channel structure and the first pores of the porous carbon, forming the active sites.

[0046] The precursor of the non-precious metal-based catalyst can be in a form containing at least one of phthalocyanine, phthalocyanine tetrasulfonate, octabutoxyphthalocyanine, hexadecafluorophthalocyanine, octakis-octyloxyphthalocyanine, tetra-tert-butylphthalocyanine, tetraazaphthalocyanine, tetraphenoxyphthalocyanine, tetra-tert-butyl-tetrakis-dimethylaminophthalocyanine, tetrakiscumylphenoxyphthalocyanine, tetrakis-pyridiniomethylphthalocyanine, tetranitrophthalocyanine, naphthalocyanine, tetra-tert-butyl-naphthalocyanine, tetraphenylporphine, tetrakis-pentafluorophenylporphyrin, tetrakis-methylpyridinioporphyrin-tetratoluenesulfonate, tetrakistrimethylammoniophenylporphyrin-tetratoluenesulfonate, or tetramethyl-divinylporphine-dipropionic acid. (engl.„tetramethyl divinyl porphinedipropionic acid“), Tetrapyridylporphin, Octaethylporphyrin, Tetrakis-methoxyphenyl-porphin, Tetraphenylporphin-tetracarbonsäure, Tetrakis-hydroxyphenyl-porphin, Tetrakis-sulfonatophenyl-porphin, Etioporphyrin, 1,10-Phenanthrolin, 1,10-Phenanthrolin-5,6-diondimethyl-1,10-phenanthrolin, 1,10-Phenanthrolin-5,6-dion, Dimethyl-1,10-phenanthrolin, Dimethoxy-1,10-phenanthrolin, Methoxy-1,10-phenanthrolin, Amino-1,10-phenanthrolin, Methyl-1,10-phenanthrolin, Dihydroxy-1,10-phenanthrolin, Tetramethyl-1,10-phenanthrolin, Chlor-1,10-phenanthrolin, Dichlor-1,10-phenanthrolin, Nitro-1,10-phenanthrolin, Brom-1,10-phenanthrolin, Tetrabrom-1,10-phenanthrolin, Pyrazino[1,10]phenanthrolin (z.B. Pyrazino[2,3-f][1,10]phenanthrolin), Diphenyl-1,10-phenanthrolin, Dimethyl-diphenyl-1,10-phenanthrolin, Ethenyl-formyl(hydroxy-trimethyltetradecyl)-trimethyl-porphin-dipropanoat (engl.„ethenyl formyl(hydroxy trimethyltetradecyl) trimethyl porphine dipropanoato“), Diethenyl-tetramethyl-porphin-dipropanoat (engl. „diethenyl tetramethyl porphine dipropanoato“), Bis((amino-carboxyethyl)thio)ethyl-tetramethyl-porphin-dipropanoat (engl. „bis((amino carboxyethyl)thio)ethyl tetramethyl porphine dipropanoato“), Dihydro-dihydroxy-tetramethyl-divinyl-porphindipropionsäurelactonat (engl. „dihydro dihydroxy tetramethyl divinyl porphine dipropionic acid lactonato“), Ethenyl(hydroxyl-trimethyl-tetradecatrienyl)-tetramethyl-porphin-dipropanoat (engl. „ethenyl(hydroxy trimethyl tetradecatrienyl) tetramethyl porphine dipropanoato“), Carboxyethenyl-carboxyethyl-dihydro-bis(hydroxymethyl)-tetramethyl-porphin-dicarboxylat (engl. „carboxyethenyl carboxyethyl dihydro bis(hydroxymethyl) tetramethyl porphine dicarboxylato“), (Dimethylbenzimidazolyl)cyanocobamid (engl.“(dimethylbenzimidazolyl)cyanocobamide”), Curtis macrocycle, Jäger macrocycle, and DOTA macrocycle are coordinated to a metal ion. In this case, the metal can have at least one of the transition metals selected from the group consisting of iron (Fe), cobalt (Co), manganese (Mn), and chromium (Cr).

[0047] Meanwhile, the types of precursor of the non-precious metal-based catalyst are not limited to this and can be broadly understood as a concept with modifications in an area obvious to the person skilled in the art.

[0048] The precursor of the non-precious metal-based catalyst may contain a transition metal, such that the weight of the transition metal is in the range of approximately 1 to 50 wt% (e.g., approximately 1 wt%, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or approximately 50 wt%) based on the total weight of the porous carbon.

[0049] If the weight of the transition metal is less than 1% by weight of the total weight of the porous carbon, the catalytically active sites cannot be adequately formed. If the weight of the transition metal is greater than 50% by weight of the total weight of the porous carbon, the precursors of the non-precious metal-based catalyst cannot all penetrate the first pores of the porous carbon and remain on its surface. Therefore, the weight of the transition metal must be adjusted based on the total weight of the porous carbon.

[0050] Meanwhile, according to one exemplary embodiment, the porous carbon can have anchor sites introduced into the surfaces of its pores to enhance the interactions between the porous carbon and the precursor of the non-precious metal-based catalyst. One process for introducing the anchor sites into the surfaces of the porous carbon's pores can involve doping the surface of the porous carbon with nitrogen atoms in various ways prior to doping the surface of the porous carbon with the precursor of the non-precious metal-based catalyst.

[0051] The probability of the formation of catalytically active sites when anchor points are or are not introduced into the surfaces of the pores of the porous carbon is described below with reference to the accompanying drawings.

[0052] Fig. Figure 8 is a diagram that schematically illustrates a reaction taking place on the surface of a pore of porous carbon, into which an anchor point has not been introduced. Fig. Figure 9 is a diagram that schematically illustrates a reaction taking place on the surface of a pore of porous carbon into which an anchor point is inserted.

[0053] Referring to Fig. 8. If the anchoring sites are not formed on the pore surfaces of the porous carbon, the interactions between the carbon particles on the pore surfaces and the precursor of the non-noble-metal-based catalyst are weak, thus reducing the probability of catalytically active sites forming. In this case, transition metal particles can form on the pore surfaces of the porous carbon over time. These transition metal particles can be eluted by an acidic solution, as will be described later.

[0054] Referring to Fig. 9. When anchor sites are formed on the pore surfaces of the porous carbon, these anchor sites can enhance the interactions between carbon particles on the pore surfaces and the precursors of the non-noble-metal-based catalyst. In other words, the agglomeration of the precursors of the non-noble-metal-based catalyst can be prevented by increasing the interaction between the carbon particles and the precursors of the non-noble-metal-based catalyst through the use of nitrogen atoms doped into the pore surfaces of the porous carbon as anchor sites. Additionally, the formation of catalytically active sites A can be increased to enhance the catalytic activity of the non-noble-metal-based catalyst.

[0055] The active site of the non-precious metal-based catalyst formed by the precursor of the non-precious metal-based catalyst and the anchoring sites can be represented by Formula 1 below. M x N y formula 1

[0056] In formula 1, x is an integer from 0 to 1, y is an integer from 1 to 4, and M is a transition metal such as iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni), and chromium (Cr).

[0057] The structure of the non-precious metal-based catalyst for fuel cell electrodes according to an exemplary embodiment has been described above. A method for producing the non-precious metal-based catalyst is described below.

[0058] Fig. Figure 10 is a schematic diagram illustrating a process for the production of a non-precious metal-based catalyst according to one embodiment. Fig. Figure 11 is a flowchart describing the process of manufacturing a non-precious metal-based catalyst.

[0059] Referring to the illustrations Fig. 10 and Fig. 11, the process of producing the non-precious metal-based catalyst according to an exemplary embodiment comprises mixing a porous carbon with a precursor of the non-precious metal-based catalyst (110), heat treatment of the mixture (120), stirring of the heat-treated mixture in an acidic solution (130) and washing and drying of the stirred mixture (140).

[0060] First, the mixing of the porous carbon with the precursor of the non-precious metal-based catalyst involves the preparation / provision of the porous carbon and the mixing of the porous carbon with the precursor of the non-precious metal-based catalyst.

[0061] The preparation of porous carbon can involve a process of synthesizing MSUFCs (e.g., mesocellular carbon foam). The MSUFC synthesis process is as follows.

[0062] First, 9 mL of furfuryl alcohol are mixed with 6 g of AIMSUF-Si, with furfuryl alcohol being added in small amounts at a time, and the mixture is held under vacuum at room temperature for 30 minutes. The vacuum is then maintained in an oven at 85°C for 8 hours. The resulting solid powder is then carbonized in an inert gas atmosphere at 850°C for 2 hours. Carbonation is carried out by increasing the temperature to 600°C at a rate of 1°C / min and to 850°C at a rate of 5°C / min. The carbonized solid powder is then added to a 2 M sodium hydroxide (NaOH) solution, and the mixture is stirred while being heated in boiling water at 80°C for 6 hours. The resulting mixture is then washed with distilled water under reduced pressure until a neutral pH is reached, and it is dried to obtain MSUFC.

[0063] However, the above-mentioned method is an example for the synthesis of MSUFC, and any other method that is obvious to a person skilled in the art can also be used for this purpose.

[0064] After completion of the synthesis of MSUFC, the porous carbon and the precursor of the non-precious metal-based catalyst are mixed.

[0065] The types of non-precious metal-based catalyst available during the mixing process of porous carbon and the non-precious metal-based catalyst (CP) precursor are as described above. In this respect, the oxygen reduction reaction activity is determined depending on the type of non-precious metal-based catalyst precursor. For better understanding, the results of experiments on the oxygen reduction reaction activity as a function of the non-precious metal-based catalyst precursor are described below.

[0066] Fig. Figure 12 is a graph illustrating results of the oxygen reduction reaction (ORR) in relation to the types of precursors of the non-noble metal-based catalyst.

[0067] Fig. Figure 12 illustrates ORR results of the first to fifth samples measured using a 0.5 M oxygen saturated sulfuric acid (H2SO4) solution, a non-noble metal-based catalyst with a loading of 815 µg / cm³ 2 and 40 wt% Pt / C at a loading rate of 16 µgpt / cm² 2 at 1600 rpm.

[0068] In this respect, the first sample is a sample of a non-precious metal-based catalyst with iron phthalocyanine as a precursor of the non-precious metal-based catalyst, the second sample is a sample of a non-precious metal-based catalyst with iron phenanthroline as a precursor of the non-precious metal-based catalyst, the third sample is a sample of a non-precious metal-based catalyst with vitamin B12 as a precursor of the non-precious metal-based catalyst, the fourth sample is a sample of a non-precious metal-based catalyst with 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine iron(III) chloride as a precursor of the non-precious metal-based catalyst, and the fifth sample is a supported catalyst in which platinum (Pt) is supported / carried on carbon.

[0069] As a result of the analysis of half-step potentials measured at -3 mA / cm 2 based on Fig. 12. It can be confirmed that the fifth sample exhibits the highest half-step potential, and that the half-step potential decreases in the order of the fourth sample, the first sample, the third sample, and the second sample. With increasing half-step potential, the catalytic activity increases. Therefore, it can be confirmed that the fifth sample with the platinum catalyst exhibits the greatest catalytic activity.

[0070] Meanwhile, it can also be confirmed that the half-step potentials of the first to fourth samples with the precursors of the non-precious metal-based catalyst are slightly lower than the half-step potential of the fifth sample. Therefore, it can be confirmed that non-precious metal-based catalysts with relatively excellent catalytic activity can be obtained by using precursors of non-precious metal-based catalysts at reduced production costs.

[0071] Meanwhile, the amount of the precursor of the non-precious metal-based catalyst can be adjusted such that, when the porous carbon is mixed with the precursor of the non-precious metal-based catalyst, the amount of transition metal contained in the precursor of the non-precious metal-based catalyst is in the range of approximately 1 to 50 wt% (e.g., approximately 1 wt%, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or approximately 50 wt%) based on the total weight of the porous carbon. The significance of the weight range of the transition metal added to the porous carbon is described above, and descriptions presented above are not repeated here.

[0072] Mixing the porous carbon with the precursor of the non-precious metal-based catalyst according to an exemplary embodiment may involve the introduction / attachment of anchor points in / to the porous carbon.

[0073] This process can be carried out to enhance the interactions between the porous carbon and the precursor of the non-precious metal-based catalyst. However, this process can be omitted.

[0074] Fig. Figure 13 is a graph illustrating oxygen reduction reaction (ORR) results depending on the introduction of anchor sites.

[0075] Fig. Figure 13 illustrates ORR results of the sixth to ninth samples measured using a 0.5 M oxygen saturated sulfuric acid (H2SO4) solution, a non-noble metal-based catalyst with a loading of 815 µg / cm³ 2 and 40 wt% Pt / C at a loading level of 16 µg pt / cm2 at 1600 rpm.

[0076] In this respect, the sixth sample is a sample of a non-precious metal-based catalyst with 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine iron(III) chloride as a precursor of the non-precious metal-based catalyst; the seventh sample is a sample of a non-precious metal-based catalyst with iron phthalocyanine as a precursor of the non-precious metal-based catalyst after the introduction of anchor sites into the porous carbon; the eighth sample is a sample of a non-precious metal-based catalyst with 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine iron(III) chloride as a precursor of the non-precious metal-based catalyst after the introduction of anchor sites into the porous carbon; and the ninth sample is a supported catalyst in which platinum (Pt) is supported on carbon.

[0077] As a result of the analysis of half-step potentials measured at -3 mA / cm2 based on the graph in Fig. 13. It can be confirmed that the seventh sample exhibits the highest half-step potential and that the half-step potential decreases in the order of the eighth, ninth, and sixth samples. In particular, a comparison between the sixth and eighth samples confirms that the eighth sample, with anchor sites introduced into the porous carbon using nitrogen, exhibits significantly higher catalytic activity than the sixth sample without anchor sites. Furthermore, since the catalytic activity of the seventh and eighth samples is higher than that of the ninth sample using the noble metal-based catalyst, it can be confirmed that the decrease in catalytic activity caused by the use of the non-noble metal-based catalyst can be prevented by introducing anchor sites.

[0078] After the porous carbon is mixed with the precursor of the non-precious metal-based catalyst, the mixture can be heat-treated.

[0079] The mixture can be heat-treated by heating it at a temperature of 600 to 1200°C in an inert gas atmosphere for approximately 10 to 300 minutes. The inert gas can be, but is not limited to, argon (Ar), nitrogen (N2), helium (He), and neon (Ne).

[0080] If the heat treatment temperature is below 600°C, the catalytically active sites are not efficiently formed on the surface of the porous carbon. If the heat treatment temperature is above 1200°C, the porous carbon structure can easily fracture. However, since the ORR performance varies between 600°C and 1200°C depending on the heat treatment temperature, the heat treatment conditions can be appropriately adjusted to achieve the desired activity of the non-precious metal-based catalyst. The variation in catalytic activity as a function of heat treatment conditions will be described later.

[0081] After heat treatment, the mixture is added to an acidic solution, and the resulting mixture can be stirred. This process is carried out to remove inactive transition metal compounds.

[0082] Stirring the heat-treated mixture in an acidic solution can involve adding the heat-treated mixture to an inorganic acidic solution with a concentration of 0.1 M or greater and stirring the resulting mixture. Types of inorganic acidic solutions can include, but are not limited to, a 0.5 M H₂SO₄ solution.

[0083] Meanwhile, the acidic solution can have a concentration of 0.1 M or higher. If the concentration of the acidic solution is less than 0.1 M, it can be difficult to sufficiently remove the inactive transition metal compounds. Therefore, the concentration of the acidic solution can be adequately controlled if necessary.

[0084] After stirring, the stirred solution is washed and dried. This process can involve continuously washing the mixture with distilled water under reduced pressure until the resulting mixture has a neutral pH, followed by drying the washed mixture.

[0085] Meanwhile, after washing and drying the stirred mixture, the solid powder obtained through the washing and drying process can be further heat-treated in an ammonia (NH3) gas atmosphere. Generally, the carbon network of the porous carbon exhibits defects. Introducing nitrogen into these defects can further increase the catalytic activity.

[0086] This process may involve heat treatment of the solid powder at a temperature of approximately 600 to 1200°C in an ammonia gas atmosphere for approximately 5 to 60 minutes.

[0087] If the heat treatment temperature is below 600°C, the surface of the non-precious metal-based catalyst cannot be efficiently doped with nitrogen. If the heat treatment temperature is above 1200°C, the porous carbon structure can easily fracture. Furthermore, the surface of the non-precious metal-based catalyst is not sufficiently doped with nitrogen if the heat treatment time is less than 5 minutes. If the heat treatment time is greater than 60 minutes, the structure of the non-precious metal-based catalyst can easily fracture. Therefore, the heat treatment temperature and time must be appropriately adjusted to efficiently introduce nitrogen into the porous carbon surface.

[0088] The variation in catalytic activity according to the heat treatment conditions is described below, with reference to the accompanying drawings. The heat treatment conditions in processes 120 and 140 are described in more detail based on the following experiments.

[0089] Fig. Figure 14 is a graph illustrating ORR results in relation to heat treatment conditions.

[0090] Fig. Figure 14 illustrates ORR results of a tenth to thirteenth sample measured using a 0.5 M oxygen saturated H2SO4 solution and a non-noble metal-based catalyst with a loading of 815 µg / cm³ 2 at 1600 rpm.

[0091] In this respect, samples ten through thirteen are samples of a non-precious metal-based catalyst with iron phthalocyanine and heat-treated under various heat treatment conditions. Specifically, sample ten is a sample of a non-precious metal-based catalyst heat-treated at 900°C in an argon gas atmosphere for 60 minutes. Sample eleven is a sample of a non-precious metal-based catalyst heat-treated at 900°C in an argon gas atmosphere for 60 minutes and then further heat-treated at 950°C in an ammonia gas atmosphere for 15 minutes. Sample twelve is a sample of a non-precious metal-based catalyst heat-treated at 1050°C in an argon gas atmosphere for 60 minutes. The thirteenth sample is a sample of a non-precious metal-based catalyst heat-treated at 1050°C in an argon gas atmosphere for 60 minutes and then further heat-treated at 950°C in an ammonia gas atmosphere for 15 minutes.

[0092] As a result of the analysis of half-step potentials measured at -3 mA / cm 2 based on the graph in Fig. 14. It can be confirmed that the tenth sample, which was heat-treated at 900°C, exhibits better catalytic activity than the twelfth sample, which was heat-treated at 1050°C. Meanwhile, a comparison of the half-stage potential between the tenth and eleventh samples and between the twelfth and thirteenth samples also confirms that the catalytic activity is further increased by the additional heat treatment of the non-noble metal-based catalyst in an ammonia gas atmosphere.

[0093] The method for producing the non-precious metal-based catalyst according to an exemplary embodiment has been described above. Conditions for efficiently incorporating the non-precious metal-based catalyst, prepared as described above, into an electrode structure of fuel cells are described below.

[0094] Meanwhile, it is necessary to determine whether the non-precious metal-based catalyst, according to an exemplary embodiment, has a 4-e pathway before describing the conditions. If the non-precious metal-based catalyst has a 4-e pathway, water (H₂O) is produced by side reactions. However, if the non-precious metal-based catalyst has a 2-e pathway, hydrogen peroxide (H₂O₂) is produced by side reactions, thereby reducing the catalyst's efficiency. Therefore, half-cell analysis results are described below to determine whether the non-precious metal-based catalyst has the 4-e pathway.

[0095] The analysis of half-cells is as follows.

[0096] First, 10 mg of the synthesized non-precious metal-based catalyst is dispersed in a mixed solution of 2 ml ethanol and 10 µl of a 5 wt% Nafion solution for 30 minutes by ultrasonic treatment / sonication. A sample of the non-precious metal-based catalyst, prepared by doping the anchoring-site porous carbon with the catalyst precursor iron phthalocyanine, is used to calculate the number of electrons involved in the reaction. Subsequently, for simplicity, the sample of the non-precious metal-based catalyst prepared by doping the anchoring-site porous carbon with the catalyst precursor iron phthalocyanine can be referred to as N-Phth.

[0097] 16 µl of the solution / dispersion prepared in this way are applied to polished glassy carbon with a diameter of 5 mm and dried at room temperature, and the aforementioned drying process is repeated once.

[0098] The electrode is connected to a rotating disk electrode and immersed in a 0.5 M oxygen-saturated H₂SO₄ solution to measure the ORR. Cyclic voltammetry (CV) is performed until a reversible hydrogen electrode (RHE) voltage of 1.0 V is reached, starting from 0.05 V through 20 cycles of linear ramp voltammetry (LSV) at a sampling rate of 10 mV / s, from 1.0 to 0.1 V. In this experiment, Koutecky-Levich graphenes are generated, as shown in the figures. Fig. 15 and Fig. 16, derived, while the electrode rotation speed is adjusted from 400 rpm to 2500 rpm, and the resulting values ​​of the Koutecky-Levich graphs are used to calculate the number of electrons involved in the reaction.

[0099] The number of electrons involved in the reaction can be determined by the following equations. 1J=1Jk+1JL jL=Bω12 B=0.62nFC0D023v−16

[0100] In equations 1 to 3, J k the kinetic current, J L is the limiting current, w is the rotational speed, F is the Faraday constant, C0 is the O2 concentration, D0 is the O2 diffusion coefficient and v is the viscosity.

[0101] The number of electrons involved in the reaction of the sample of the non-precious metal-based catalyst according to an exemplary embodiment, calculated using equations 1 to 3 and the Koutecky-Levich graphs / plots, is 3.95 at 0.7 V.

[0102] Based on the results of experiments, it can be confirmed that the non-precious metal-based catalyst according to an exemplary embodiment possesses a 4-e pathway. In other words, the non-precious metal-based catalyst according to an exemplary embodiment exhibits high catalytic activity through the elimination of superfluous side reactions.

[0103] The following describes conditions for the efficient incorporation of the non-precious metal-based catalyst into an electrode structure of fuel cells; in other words, experimental examples for deriving conditions for realizing fuel cells optimized for the non-precious metal-based catalyst according to one embodiment.

[0104] For this purpose, a single cell is assembled after the fabrication of a membrane electrode assembly / device, and the performance of the single cell is analyzed.

[0105] A process for manufacturing the membrane electrode assembly and a process for joining / assembling the individual cell are as follows.

[0106] First, a non-precious metal-based catalyst solution / dispersion is prepared according to an exemplary embodiment. In particular, 50 g of the non-precious metal-based catalyst, prepared by doping the porous carbon with anchoring sites with iron phthalocyanine, are dispersed in 5 ml of a mixed solution of 5 wt% Nafion solution and isopropanol for 30 minutes to prepare a non-precious metal-based catalyst solution.

[0107] Furthermore, a platinum catalyst solution, used as a material for forming the anode of the membrane electrode assembly, is prepared as follows. 50 mg of a platinum catalyst are dispersed in a mixed solution of 0.2 ml distilled water, 5 ml isopropanol, and 428.6 mg of a 5 wt% Nafion solution for 30 minutes to prepare a platinum catalyst solution.

[0108] The non-precious metal-based catalyst solution is applied to the surface of a 1.5 cm x 1.5 cm electrode by hand spraying using catalyst-coated substrate (CCS) and catalyst-coated membrane (CCM) methods / processes. A single cell is then assembled by fixing it with a torque of 25 kgf*cm.

[0109] Specifically, the non-precious metal-based catalyst solution is applied to carbon paper (SGL 35 BC) using the CCS method, and the non-precious metal-based catalyst solution is applied to a Nafion membrane (Nafion 211) using the CCM method. However, even when applying via the CCS method, hot pressing at 125°C for 1 minute under a pressure of 70 kgf / cm² is performed. 2The process is carried out in the same way. The platinum catalyst solution is applied to carbon paper and a Nafion membrane. This process yields 0.2 mg. pt / cm 2 a platinum catalyst loaded onto an anode, and 0.5 to 3 mg / cm² 2 The non-precious metal-based catalyst is loaded onto a cathode.

[0110] Next, the performance of each individual cell will be analyzed under the following conditions.

[0111] The generally applied conditions for analyzing the performance of each cell in the figures Fig. 17, Fig. 18, Fig. 19 to Fig. The procedures are as follows. First, the power output of each cell is measured after it has been held at an open-circuit voltage for 2 hours at 65°C and 100% humidity, while hydrogen and air are supplied such that the amounts of hydrogen and air are 1.5 and 2 times, respectively, their stoichiometric amounts. Methods for controlling the process conditions are described in more detail later.

[0112] First, an optimal spraying method used to prepare the individual cell is described with reference to Fig. 17 described.

[0113] Fig. Figure 17 is a graph illustrating changes in the performance of individual cells with respect to the spraying method.

[0114] Fig. Figure 17 illustrates a comparison of performance between a single cell with MEA prepared using the CCS method and a single cell with MEA prepared using the CCM method. Here, 0.2 mg is used. pt / cm 2 a platinum catalyst loaded onto an anode and 0.5 mg / cm² 2 The N-Phth molecules are loaded onto a cathode. Meanwhile, a mass ratio of Nafion to catalyst of 1:1.5 is used in the solution during spraying.

[0115] Referring to Fig. 17. It can be confirmed that the current density and power density obtained by the CCM method are higher than those obtained by the CCS method at the same potential.

[0116] In general, a higher current density at the same potential indicates higher catalytic activity, and a higher power density at the same potential indicates better cell performance. Therefore, it can be confirmed that the individual cell obtained using the CCM method exhibits better performance than the cell obtained using the CCS method.

[0117] Next, an optimal composition ratio of the catalyst solution used to produce the individual cell will be determined with reference to Fig. 18 described.

[0118] Fig. Figure 18 is a graph illustrating changes in the performance of a single cell with respect to the mass ratio of the Nafion ionomer to the non-precious metal-based catalyst added to the catalyst solution. Here, 0.2 mg pt / cm 2 a platinum catalyst loaded onto an anode, and 0.5 mg / cm² 2The N-Phth molecules are loaded onto a cathode. Meanwhile, the CCM method is used as a spray method.

[0119] Each of the fourteenth to eighteenth samples used in this experiment is an N-Phth catalyst sample. In preparing each cell using the non-precious metal-based catalyst according to one embodiment, the catalyst solution is prepared by mixing the non-precious metal-based catalyst with the Nafion ionomer and ethanol. To find an optimal ratio of the non-precious metal-based catalyst, different mass ratios of the Nafion ionomer to the N-Phth catalyst are used in the fourteenth to eighteenth samples. For simplicity, a mass ratio of the Nafion ionomer to the non-ionic catalyst in the preparation of the catalyst solution is subsequently referred to as the Nafion to catalyst ratio (NCR).The fourteenth sample is prepared by setting the NCR to 1.5, the fifteenth sample is prepared by setting the NCR to 2, the sixteenth sample is prepared by setting the NCR to 2.5, the seventeenth sample is prepared by setting the NCR to 3, and the eighteenth sample is prepared by setting the NCR to 3.5.

[0120] The graph will be done in the same way as Fig. 17. It can be confirmed that the single cell exhibits the best performance at an NCR of 2.5. It can be confirmed that a relatively large amount of the Nafion ionomer is necessary to efficiently utilize the non-precious metal-based catalyst according to an exemplary embodiment due to the large surface area of ​​the catalyst. Conversely, if the NCR is greater than 2.5, the performance of the single cell deteriorates. Therefore, it can be confirmed that an excess of the Nafion ionomer can interrupt the oxygen supply, thereby deteriorating the performance of the single cell.

[0121] Next, an optimal catalyst loading quantity necessary for the preparation / provision of a single cell will be determined in relation to Fig. 19 described.

[0122] Fig. Figure 19 is a graph illustrating changes in the performance of individual cells in relation to the amount of catalyst loaded. Here, 0.2 mg is used. pt / cm 2 A platinum catalyst is loaded onto an anode and a catalyst solution with an NCR of 2.5 is loaded onto the cathode using the CCM method.

[0123] Each of the nineteenth to twenty-second samples used in this experiment is a sample of the N-Phth catalyst. To find the optimal amount of the non-noble metal-based catalyst, the amounts of catalyst loaded onto the cathode during the preparation of each cell are modified. The nineteenth sample is obtained by adjusting the catalyst loading to 0.5 mg / cm². 2 The twentieth sample is obtained by adjusting the catalyst loading to 1.0 mg / cm³. 2 The twenty-first sample is obtained by adjusting the catalyst loading to 1.5 mg / cm³. 2The twenty-second sample is obtained by adjusting the catalyst loading to 3.0 mg / cm³. 2 receive.

[0124] The graph is created in the same way as Fig. 17 interpreted. It can be confirmed that the performance of the individual cell is improved while the catalyst loading amount remains at 0.5 mg / cm². 2 up to 3.0 mg / cm² 2 This is increased. This is due to the efficient reduction of mass transport resistance by pores with a diameter of 20 nm or larger formed on the surface of the non-precious metal-based catalyst according to one embodiment.

[0125] Next, durability tests will be carried out on individual cells manufactured using non-precious metal-based catalysts according to an embodiment, with reference to Fig. 20 described.

[0126] Fig. Figure 20 is a graph illustrating the results of single-cell stability tests. Here, 0.2 mg is used. pt / cm 2 a platinum catalyst loaded onto an anode and 3.0 mg / cm² 2 The N-Phth catalyst is loaded onto a cathode. In this context, the non-precious metal-based catalyst solution with an NCR of 2.5 is loaded onto the cathode using the CCM method.

[0127] First, the initial power of each cell is measured, and the result is shown as G1. Then, after 1500 cycles at 50 mV / s between 0.6 V and 1.0 V, the power of each cell is measured, and the result is shown as G2.

[0128] It can be confirmed that the activity is reduced by approximately 2.2% at 0.6 V based on the measured current densities. Therefore, it can be confirmed that the single cell prepared with the non-precious metal-based catalyst according to an exemplary embodiment possesses excellent durability.

[0129] Experimental examples for deriving conditions for the implementation of fuel cells optimized for non-precious metal-based catalysts according to an exemplary embodiment have been described.

[0130] According to the non-precious metal-based catalyst and the fuel cell that uses it and is prepared according to the aforementioned procedures, catalytically active sites form only on the surface of larger pores beneath the pores of the porous carbon by adjusting the manufacturing process conditions. Therefore, the reactants readily reach the catalytically active sites in a real-world operating / driving environment, and the catalytically active sites can be utilized more efficiently.

[0131] The following section discusses the effects of the position of the catalytically active sites on the improved utilization of the catalytically active sites with regard to Fig. 21, Fig. 22 to Fig. 23 described.

[0132] Fig. Figure 21 is a diagram illustrating the reactions of reactants according to the positions of catalytically active sites. Fig. 22 and Fig. Figure 23 are graphs illustrating ORR results and changes in the performance of individual cells in relation to the positions of the catalytically active sites.

[0133] If the catalytically active site is at the second pore, which is shown in the left graph of Fig. Figure 21 illustrates an ultrafine pore, which means that a reactant cannot easily reach the catalytically active site, and therefore the functions of the catalytically active site A cannot be efficiently carried out.

[0134] In contrast, in the sample of the non-precious metal-based catalyst according to one embodiment, the catalytically active site is located at the first pore, as shown in the right-hand graph of Fig. Figure 21 illustrates a micropore that has formed. Therefore, the functions of the catalytically active site A can be carried out efficiently.

[0135] Fig. Figure 22 illustrates ORR results of a twenty-third to twenty-fifth sample measured using a 0.5 M oxygen saturated H2SO4 solution, a non-noble metal-based catalyst with a loading of 815 µg / cm³ 2 and 40 wt% Pt / C at a loading rate of 16 µgpt / cm² 2 at 1600 rpm. The catalytically active sites are formed not only in the first pores but also in the second pores of the twenty-third sample. The twenty-fourth sample was prepared using N-Phth, and the twenty-fifth sample was prepared using a commonly used platinum catalyst.

[0136] Fig. Figure 23 illustrates changes in the performance of individual cells prepared using the twenty-third and twenty-fourth samples after holding the individual cells at 65°C while hydrogen and air were supplied such that the amounts of hydrogen and air were 1.5 and 2, respectively, as their stoichiometric amounts. Here, 0.2 mg pt / cm 2 a platinum catalyst loaded onto an anode, 3.0 mg / cm² 2 of the N-Phth are charged onto a cathode, and the NCR in the catalyst solution used during the spraying process is 2.5.

[0137] Referring to the Fig. 22 and Fig.23. It can be confirmed that the voltage drops rapidly when the current density increases in the twenty-third sample, in which the catalytically active sites are formed in the ultrafine pores. This is due to the increasing mass transport resistance caused by the difficulty of reaching the catalytically active sites.

[0138] However, the voltage in the twenty-fourth sample does not drop rapidly when the current density increases, and the twenty-fourth sample shows better individual cell performance than the twenty-third sample.

[0139] Based on the experimental results, it can be confirmed that the catalytically active sites can be used more efficiently by allowing the reactants to easily reach the active sites in the actual operating environment by selectively controlling the position of the catalytically active sites formed at the pores of the porous carbon.

[0140] As can be seen from the above description, according to the non-precious metal-based catalyst and the method for its production, the utilization of the catalytically active sites can be increased by enabling the reactants to easily reach the active sites in the actual operating environment, by ensuring that the active sites are formed only on the surfaces of the micropores beneath the pores of the porous carbon, and by controlling the conditions during the production process.

[0141] Furthermore, excellent catalyst performance can be achieved by reducing the mass transport resistance in the membrane electrode structure through the introduction of a nanoporous carbon structure with a regular structure and relatively large pores within it.

[0142] Furthermore, the catalytic activity can be improved by enhancing the interaction with the catalyst's precursors through the introduction of anchoring sites into the surface of the porous carbon.

[0143] The preceding descriptions of specific exemplary embodiments of the present invention have been presented for illustrative and descriptive purposes. They are not intended to be exhaustive or to limit the invention to the exact form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments have been selected and described to explain certain principles of the invention and their practical application, thereby enabling those skilled in the art to produce and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention is defined by the claims attached herein and their equivalents.

Claims

A non-precious metal-based catalyst for a fuel cell electrode, comprising: a porous carbon with a first pore (H1) and a second pore (H2) that is smaller than the first pore (H1), wherein the first pore (H1) has a pore size of 5 to 100 nm and an active site (A) of the non-precious metal-based catalyst is selectively attached only to an inner wall of the first pore (H1), wherein the active site (A) of the non-precious metal-based catalyst is formed by a precursor of the non-precious metal-based catalyst (CP), and wherein the precursor of the non-precious metal-based catalyst (CP) has a form in which at least one of phthalocyanine, phthalocyanine tetrasulfonate, octabutoxyphthalocyanine, hexadecafluorophthalocyanine, octakis-octyloxyphthalocyanine, Tetra-tert-butyl-phthalocyanine, tetraazaphthalocyanine, tetraphenoxyphthalocyanine, tetra-tert-butyl-tetrakis-dimethylamino-phthalocyanine, tetrakiscumylphenoxy-phthalocyanine,Tetrakis-pyridiniomethyl-phthalocyanin, Tetranitrophthalocyanin, Naphthalocyanin, Tetra-tert-butyl-naphthalocyanin, Tetraphenylporphin, Tetrakis-pentafluorphenyl-porphyrin, Tetrakis-methylpyridinioporphyrin-tetratoluolsulfonat, Tetrakistrimethylammoniophenyl-porphyrin-tetratoluolsulfonat, Tetramethyl-divinyl-porphindipropionsäure, Tetrapyridylporphin, Octaethylporphyrin, Tetrakis-methoxyphenyl-porphin, Tetraphenylporphin-tetracarbonsäure, Tetrakis-hydroxyphenyl-porphin, Tetrakis-sulfonatophenyl-porphin, Etioporphyrin, 1,10-Phenanthrolin, 1,10-Phenanthrolin-5,6-diondimethyl-1,10-phenanthrolin, 1,10-Phenanthrolin-5,6-dion, Dimethyl-1,10-phenanthrolin, Dimethoxy-1,10-phenanthrolin, Methoxy-1,10-phenanthrolin, Amino-1,10-phenanthrolin, Methyl-1,10-phenanthrolin, Dihydroxy-1,10-phenanthrolin, Tetramethyl-1,10-phenanthrolin, Chlor-1,10-phenanthrolin, Dichlor-1,10-phenanthrolin, Nitro-1,10-phenanthrolin, Brom-1,10-phenanthrolin, Tetrabrom-1,10-phenanthrolin, Pyrazino[1,10]phenanthrolin,Diphenyl-1,10-phenanthroline, dimethyl-diphenyl-1,10-phenanthroline, ethenyl-formyl(hydroxy-trimethyltetradecyl)-trimethyl-porphine-dipropanoate, diethenyl-tetramethyl-porphine-dipropanoate, bis((amino-carboxyethyl)thio)ethyl-tetramethyl-porphine-dipropanoate, Dihydro-dihydroxy-tetramethyl-divinyl-porphine dipropionic acid lactonate, Ethenyl(hydroxyl-trimethyl-tetradecatrienyl)-tetramethyl-porphine-dipropanoate, Carboxyethenyl-carboxyethyl-dihydro-bis(hydroxymethyl)-tetramethyl-porphine-dicarboxylate, (Dimethylbenzimidazolyl)cyanocobamide, Curtis macrocycle, Jäger macrocycle and DOTA macrocycle is coordinated to a metal. The non-precious metal-based catalyst according to claim 1, wherein the porous carbon has a structure in which the first pore (H1) and the second pore (H2) are uniformly connected in a three-dimensional space. The non-precious metal-based catalyst according to claim 1 or 2, wherein the first pore (H1) has a pore size of 15 to 60 nm. The non-precious metal-based catalyst according to claim 1, wherein the metal comprises at least one transition metal selected from iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni) and chromium (Cr). The non-precious metal-based catalyst according to one of the preceding claims, wherein the precursor of the non-precious metal-based catalyst (CP) contains a transition metal with a weight / proportion of 1 to 50 wt% based on the total weight of the porous carbon. The non-precious metal-based catalyst according to one of the preceding claims, wherein the porous carbon has an anchoring site (AN) which is incorporated into a surface of a pore (CS) of the porous carbon to enhance interactions between the porous carbon and the precursor of the non-precious metal-based catalyst (CP). A process for producing a non-precious metal-based catalyst for a fuel cell electrode, comprising: mixing a porous carbon with a precursor of a non-precious metal-based catalyst (CP) (110); heat treatment of the mixture at a temperature of 600 to 1200°C (120); stirring of the heat-treated mixture in an acidic solution (130); and washing and drying of the stirred mixture (140), wherein, upon mixing the porous carbon with the precursor of the non-precious metal-based catalyst (CP), the porous carbon has a first pore (H1) and a second pore (H2) that is smaller than the first pore (H1), and the first pore (H1) has a pore size of 5 to 100 nm, and an active site (A) of the non-precious metal-based catalyst is selectively located only on an inner wall of the first pore (H1). is attachedand when mixing the porous carbon with the precursor of the non-precious metal-based catalyst (CP), the precursor of the non-precious metal-based catalyst (CP) has a form in which at least one of phthalocyanine, phthalocyanine tetrasulfonate, octabutoxyphthalocyanine, hexadecafluorophthalocyanine, octakis-octyloxyphthalocyanine, tetra-tert-butylphthalocyanine, tetraazaphthalocyanine, tetraphenoxyphthalocyanine, tetra-tert-butyl-tetrakisdimethylaminophthalocyanine, tetrakis-cumylphenoxyphthalocyanine, tetrakis-pyridiniomethylphthalocyanine, tetranitrophthalocyanine, naphthalocyanine, tetra-tert-butyl-naphthalocyanine, tetraphenylporphine, tetrakis-pentafluorophenylporphyrin, tetrakis-methylpyridinioporphyrin-tetratoluenesulfonate, Tetrakistrimethylammoniophenyl porphyrin tetratoluenesulfonate, tetramethyldivinylporphindipropionic acid, tetrapyridylporphine, octaethylporphyrin, tetrakismethoxyphenylporphine, tetraphenylporphinetetracarboxylic acid, tetrakishydroxyphenylporphine,Tetrakis-sulfonatophenyl-porphin, Etioporphyrin, 1,10-Phenanthrolin, 1,10-Phenanthrolin-5,6-diondimethyl-1,10-phenanthrolin, 1,10-Phenanthrolin-5,6-dion, Dimethyl-1,10-phenanthrolin, Dimethoxy-1,10-phenanthrolin, Methoxy-1,10-phenanthrolin, Amino-1,10-phenanthrolin, Methyl-1,10-phenanthrolin, Dihydroxy-1,10-phenanthrolin, Tetramethyl-1,10-phenanthrolin, Chlor-1,10-phenanthrolin, Dichlor-1,10-phenanthrolin, Nitro-1,10-phenanthrolin, Brom-1,10-phenanthrolin, Tetrabrom-1,10-phenanthrolin, Pyrazino[1,10]phenanthrolin, Diphenyl-1,10-phenanthrolin, Dimethyl-diphenyl-1,10-phenanthrolin, Ethenyl-formyl(hydroxy-trimethyltetradecyl)-trimethyl-porphin-dipropanoat, Diethenyl-tetramethyl-porphin-dipropanoat, Bis((amino-carboxyethyl)thio)ethyl-tetramethyl-porphin-dipropanoat, Dihydro-dihydroxy-tetramethyl-divinyl-porphindipropionsäurelactonat, Ethenyl(hydroxyl-trimethyl-tetradecatrienyl)-tetramethyl-porphin-dipropanoat,Carboxyethenyl carboxyethyl dihydro-bis(hydroxymethyl)-tetramethyl-porphine dicarboxylate, (dimethylbenzimidazolyl)cyanocobamide, Curtis macrocycle, Jäger macrocycle and DOTA macrocycle are coordinated to a metal. The method according to claim 7, wherein the first pore (H1) has a pore size of 15 to 60 nm. The method according to claim 7 or 8, further comprising heat-treating a solid powder obtained after drying in an ammonia gas atmosphere (NH3) at a temperature of 600 to 1200°C for 5 to 60 minutes. The method according to one of claims 7 to 9, further comprising forming an anchor point (AN) on / at a surface of a pore (CS) of the porous carbon by heat-treating the porous carbon in an ammonia gas atmosphere (NH3) at a temperature of 600 to 1200°C for 5 to 60 minutes. The method according to claim 7, wherein the metal comprises at least one transition metal selected from iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni) and chromium (Cr). The method according to any one of claims 7 to 11, wherein, when mixing the porous carbon with the precursor of the non-precious metal-based catalyst (CP), the precursor of the non-precious metal-based catalyst (CP) comprises a transition metal with a weight / proportion of 1 to 50 wt% based on the total weight of the porous carbon. The method according to one of claims 7 to 12, wherein the heat treatment of the mixture at a temperature of 600 to 1200°C comprises a heat treatment of the mixture in an inert gas atmosphere at a temperature of 600 to 1200°C for 10 to 300 minutes. The method according to any one of claims 7 to 13, wherein the stirring of the heat-treated mixture in an acidic solution comprises adding the heat-treated mixture to an acidic solution having a concentration of 0.1 M or greater and stirring the resulting mixture.

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