Porous carbon body for fuel cell catalyst support

Abstract

The porous carbon material described in this disclosure is a porous carbon material for fuel cell catalyst support to support a catalyst material in a fuel cell, and more specifically, the porous carbon material contains 0.50 to 5.00 at% nitrogen and has a zeta potential of 0 mV or higher.

Description

[Technical Field]

[0001] This invention relates to a porous carbon material for supporting a fuel cell catalyst. [Background technology]

[0002] Polymer electrolyte membrane fuel cells (PEMFCs), which are highly energy-efficient and environmentally friendly, are attracting attention as an alternative energy source to fossil fuels.

[0003] A PEMFC is a power generation system that produces electricity through an electrochemical reaction of hydrogen and oxygen using a catalyst, and has a structure in which unit cells containing membrane-electrode assemblies (MEAs) and bipolar plates are stacked. The MEA has a structure in which cation exchange membranes (also called polymer electrolyte membranes) are inserted into the anode and cathode.

[0004] A crucial factor determining the performance of a fuel cell is the catalyst used to form the electrodes (anode and cathode) of the MEA, which is generally used by supporting platinum-based catalyst particles on a porous carbon body.

[0005] Porous carbon bodies not only support catalyst particles but also affect catalytic activity and durability. To improve catalytic activity and durability, research is being conducted to improve the carbon body itself, such as its crystallinity, porosity structure, and specific surface area, as well as to improve its properties by modifying the carbon body through doping with different elements.

[0006] As methods for synthesizing nitrogen-doped porous carbon materials, there are broadly post-treatment methods and methods using templates. The post-treatment method is a method of supplying a nitrogen source such as ammonia or urea to a carbon matrix and performing heat treatment. This method not only has a complicated process but also has the drawback that the efficiency of nitrogen doping is not good. The method using a template is a process of introducing a carbon source containing nitrogen into a template such as silica, performing carbonization treatment, and then removing the template. Such a method using a template has drawbacks such as complicated processes including template manufacturing, carbon source filling, carbonization treatment, and template removal, high costs, and limitations in commercialization. Even though the template removal process is carried out, contamination by the template material cannot be avoided.

Summary of the Invention

Problems to be Solved by the Invention

[0007] According to one embodiment of the present invention, a nitrogen-doped porous carbon material can be provided.

[0008] According to another embodiment of the present invention, a nitrogen-doped porous carbon material at a target site can be provided.

[0009] According to still another embodiment of the present invention, a nitrogen-doped porous carbon material in a bonding form advantageous for the durability and / or activity of a fuel cell catalyst can be provided.

[0010] According to yet another embodiment of the present invention, a porous carbon material with improved durability and / or activity of a fuel cell catalyst can be provided.

[0011] The problems of the present invention are not limited to the above-described content. For those with ordinary knowledge in the technical field to which the present invention pertains, there is no difficulty in understanding further problems of the present invention from the entire content of this specification.

Means for Solving the Problems

[0012] A porous carbon material according to one embodiment of the present invention is a porous carbon material for fuel cell catalyst support, containing 0.50 to 5.00 at% nitrogen and having a zeta potential of 0 mV or higher.

[0013] In one specific example, the zeta potential of the porous carbon material can be 1.00 to 50.00 mV.

[0014] In one specific example, the ratio of nitrogen in a pyridinic N bond state to nitrogen in a pyrrolic N bond state among the total nitrogen contained in the porous carbon material can be between 1.0 and 3.5.

[0015] In one specific example, of the total nitrogen contained in the porous carbon material, the proportion of nitrogen in a pyridinic N bond state may be 40% or more, and the proportion of nitrogen in a pyrrolic N bond state may be 20% or more.

[0016] In one specific example, the oxygen content of the porous carbon material can be 1.5 at% or less.

[0017] In one specific example, the porous carbon material contains oxygen, and the ratio of the nitrogen content (at%) in the porous carbon material to the oxygen content (at%) can be between 1.0 and 5.0.

[0018] In one specific example, the proportion of oxygen containing O2 bonds in the porous carbon material can be 20% or more.

[0019] In one specific example, the pore volume of the porous carbon material is 0.5 to 5.0 cm³. 3 It can be / g

[0020] In one specific example, the average pore size of the porous carbon material can be 3 to 20 nm.

[0021] In one specific example, the porous carbon material can have a crystal size of 2.0 to 5.5 nm, as calculated from its X-ray diffraction pattern.

[0022] In one specific example, the cumulative volume median diameter (D) of the porous carbon body. 50 The size can be between 0.1 and 12 μm.

[0023] A fuel cell catalyst according to one embodiment of the present invention includes the aforementioned porous carbon body.

[0024] A catalyst layer for a fuel cell according to one embodiment of the present invention contains the aforementioned catalyst and ionomer.

[0025] A fuel cell according to one embodiment of the present invention includes the catalyst described above. [Effects of the Invention]

[0026] A porous carbon material according to one embodiment of the present invention can improve catalyst durability and activity when used as a fuel cell catalyst support.

[0027] The diverse and beneficial advantages and effects of the present invention are not limited to those described above and can be more easily understood in the process of describing specific embodiments of the present invention. [Modes for carrying out the invention]

[0028] Preferred embodiments of the present invention will be described below. However, embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0029] Furthermore, embodiments of the present invention are provided to more fully explain the invention to a person with average skill in the art.

[0030] In describing embodiments of the present invention, if a detailed explanation of prior art related to the present invention is deemed to unnecessarily obscure the gist of the invention, such detailed explanation will be omitted. Furthermore, the terms described later are defined considering the function of the present invention, and these may change depending on the intent or conventions of the user or operator. Therefore, their definitions should be determined based on the content of this specification as a whole. The terms used in the detailed description are merely for describing embodiments of the present invention and are not restrictive. Unless otherwise specified, singular expressions include the meaning of the plural form.

[0031] In this description, expressions such as “includes” or “equip” are intended to refer to a particular characteristic, number, stage, action, element, part thereof, or combination thereof, and should not be interpreted as excluding the existence or possibility of one or more other characteristics, numbers, stages, actions, elements, part thereof, or combination thereof other than those described.

[0032] The present invention will be described in detail below through various embodiments or examples of the present invention. It should be noted that each embodiment or example described herein is not merely limited to a single embodiment or example, but can also be combined with other embodiments or examples. Therefore, the references to the claims in the claims are merely examples of embodiments, and the technical idea of ​​the present invention should not be interpreted only in combination with the cited claim, but rather various combinations with other claims are also included within the scope of the technical idea of ​​the present invention.

[0033] The inventors conducted various studies to develop a support for fuel cell catalysts by selectively doping a base carbon with high concentrations of nitrogen using nitrogen-containing polymers. During the research process, they discovered that by surface-treating the base carbon and controlling the molecular weight of a specific polymer, as well as controlling the contact conditions between the base carbon and the polymer, the surface properties of the nitrogen-doped porous carbon body change, the zeta potential of the carbon body becomes positive, and the durability of the catalyst is greatly improved. This led to the completion of the present invention.

[0034] Based on the above findings, the porous carbon material disclosed herein is a porous carbon material for fuel cell catalyst support, which is nitrogen-doped, contains 0.50 to 5.00 at% nitrogen, and has a zeta potential of 0 mV or higher. In the present invention, the zeta potential can be the zeta potential in ethanol.

[0035] In one specific example, the porous carbon body is doped with nitrogen and has a zeta potential of 0 mV or higher, specifically a positive zeta potential. This suppresses catalytic degradation on the support surface, which is the main cause of degradation, and thus improves durability.

[0036] As a specific example, the zeta potential of a porous carbon material can be 0mV or higher, 0.5mV or higher, 1.0mV or higher, 1.5mV or higher, 3.0mV or higher, 5.0mV or higher, 7.0mV or higher, or 10.0mV or higher, and as a practical example, it can be 100mV or lower, 80mV or lower, 60mV or lower, 50mV or lower, or 45mV or lower. As a more practical example, the zeta potential of porous carbon materials is as follows: 0mV~100mV, 0.5mV~100mV, 1.0mV~100mV, 1.5mV~100mV, 3.0mV~100mV, 5.0mV~100mV, 7.0mV~100mV, 10.0mV~100mV, 0mV~60mV, 0.5mV~60mV, 1.0mV~60mV, 1.5mV~60mV, 3.0mV~60mV, 5.0mV~60mV, 7.0mV~60mV, The values ​​can be 10.0mV~60mV, 0mV~50mV, 0.5mV~50mV, 1.0mV~50mV, 1.5mV~50mV, 3.0mV~50mV, 5.0mV~50mV, 7.0mV~50mV, 10.0mV~50mV, 0mV~45mV, 0.5mV~45mV, 1.0mV~45mV, 1.5mV~45mV, 3.0mV~45mV, 5.0mV~45mV, 7.0mV~45mV, or 10.0mV~45mV.

[0037] As a specific example, the nitrogen content contained in the porous carbon material having the aforementioned zeta potential can be 0.50-5.00 at%, 0.5-4.5 at%, 0.5-4.0 at%, 0.5-3.5 at%, 0.5-3.0 at%, 0.5-2.5 at%, or 0.5-2.0 at%. In this case, the nitrogen content contained in the porous carbon material can be a value based on X-ray photoelectron spectroscopy analysis of the porous carbon material.

[0038] As a favorable example, the ratio (hereinafter also referred to as the N1 / N2 ratio) obtained by dividing the total nitrogen contained in the porous carbon body by the proportion of nitrogen in a pyrrolic N bond state (hereinafter also referred to as N2 nitrogen) can be 1.0 to 3.5, 1.0 to 3.0, or 1.0 to 2.5. With a zeta potential of 0 mV or higher, preferably a positive zeta potential, and an N1 / N2 ratio of 1.0 to 3.5, preferably 1.0 to 3.0, and more preferably 1.0 to 2.5, the surface of the porous carbon body can exhibit both a strong affinity for catalytic components and a strong affinity for ionomers.

[0039] In one specific example, the proportion of N1 nitrogen in the total nitrogen contained in the porous carbon body can be 40% or more, and the proportion of N2 nitrogen can be 20% or more. N1 nitrogen with a zeta potential of 0mV or higher, preferably a positive zeta potential, along with negative polarity (or electron acceptor action), can enhance electrostatic affinity with catalytic material on the surface of the porous carbon body. N2 nitrogen with a zeta potential of 0mV or higher, preferably a positive zeta potential, along with positive polarity (or electron donor action), can enhance electrostatic affinity with ionomer on the surface of the porous carbon body.

[0040] More specifically, the proportion of N1 nitrogen in the total nitrogen contained in the porous carbon material can be 40-60%, more specifically 40-55%, and more specifically 40-50%. In addition, the proportion of N2 nitrogen in the total nitrogen contained in the porous carbon material can be 20-50%, more specifically 20-45%.

[0041] In one specific example, the sum of the proportions of N1 nitrogen and N2 nitrogen in the total nitrogen contained in the porous carbon material can be 60% or more, specifically 60-100%, more specifically 60-95%, more specifically 60-90%, and even more specifically 65-90%. When the zeta potential is 0mV or higher, preferably a positive zeta potential, and the content of N1 and N2 nitrogen in the total nitrogen contained in the porous nitrogen material is high within the aforementioned range, the initial efficiency and durability of the catalyst can be significantly improved when used as a fuel cell catalyst support.

[0042] In one advantageous example, a porous carbon body can contain oxygen along with nitrogen, with an oxygen content of 1.5 at% or less, specifically between 0 and 1.5%, more specifically between 0 and 1.0 at%, and even more specifically between 0.4 and 0.9 at%. In this case, the oxygen content contained in the porous carbon body can be a value based on X-ray photoelectron spectroscopy analysis of the porous carbon body. Because the porous carbon body has the aforementioned trace amount of oxygen, it can have a uniformly nitrogen-doped surface (outermost surface), resulting in a low concentration of oxygen-derived defects and improved durability of the carbon body.

[0043] In one specific example, the proportion of oxygen containing O2 bonds in the porous carbon material can be 15% or more, specifically 15-80%, more specifically 20-70%, and even more specifically 20-60%. Oxygen containing O2 bonds is substantially the most stable bond that oxygen can form within the carbon structure. As a result, such a high proportion of O2-bonded oxygen can minimize adverse effects on the carbon material during electrochemical reactions and / or in operating environments such as temperature and gases supplied to and generated in fuel cells, thereby improving the durability of the porous carbon material.

[0044] In one specific example, the nitrogen content (at%) contained in the porous carbon material is N tot (Also known as) the oxygen content (at%, hereafter referred to as O tot The ratio obtained by dividing by (also known as) (hereinafter, N tot / Otot (also referred to as) can be 1.0 to 5.0, specifically 1.0 to 4.5, more specifically 1.0 to 4.0, still more specifically 1.0 to 3.5, and even more specifically 1.5 to 3.5. As described above, the porous carbon body contains both nitrogen and oxygen, but can contain relatively high concentrations of nitrogen and low concentrations of oxygen. In a porous carbon body containing 0.50 to 5.00 at% of nitrogen, the aforementioned N tot / O tot The low concentration of oxygen that satisfies is a prerequisite and a necessary requirement that must be satisfied in order for relatively high concentrations of nitrogen to be uniformly doped and contained throughout the surface of the porous carbon body.

[0045] In one specific example, the pore volume of the porous carbon body is 0.5 to 5.0 cm 3 / g, specifically 0.5 to 4.0 cm 3 / g, more specifically 0.5 to 3.0 cm 3 / g, even more specifically 1.0 to 2.5 cm 3 / g, but is not limited thereto. The aforementioned pore volume is advantageous in terms of providing a large specific surface area capable of supporting a catalyst substance, but the pore volume of the porous carbon body is not necessarily limited thereto. As an example, in order to enhance the crystallographic perfection of the porous carbon body, a porous carbon body having a pore volume lower than the aforementioned pore volume can be adopted as a support. As another example, a porous carbon body having a pore volume higher than the aforementioned pore volume can be adopted as a support so that a larger amount of catalyst substance can be supported.

[0046] In one specific example, the average pore size of a porous carbon material can be 3-20 nm, more specifically 5-15 nm, and more specifically 7-10 nm, but is not limited to these values. However, such an average pore size means that the pores mainly formed in the porous carbon material belong to the mesoporous region (according to the IUPAC definition). Pores in this mesoporous region can support catalytic material inside the pores, preventing direct contact between the ionomer and the catalytic material inside the pores, and enabling smooth diffusion of reactants and reaction products during electrochemical reactions.

[0047] In one specific example, the specific surface area of ​​a porous carbon body is 200-1500 m². 2 / g, 200-800m 2 / g, or 800-1500m 2 It can be / g, but is not limited to this.

[0048] In one specific example, the crystal size calculated from the X-ray diffraction pattern of a porous carbon body can be, but is not limited to, 2.0–5.5 nm, 2.0–5.0 nm, or 2.0–4.0 nm.

[0049] In one specific example, the cumulative volume median diameter (D) of the porous carbon body 50 The particle size can be, but is not limited to, 0.1 to 12 μm, more specifically 0.5 to 10 μm, or more specifically 1 to 10 μm.

[0050] The present invention includes a fuel cell catalyst containing the aforementioned porous carbon material.

[0051] The fuel cell catalyst described in this disclosure includes the porous carbon body described above, and a catalytic substance (catalytically active substance) supported on the porous carbon body described above, with the porous carbon body as the support.

[0052] The catalytic material may include platinum-based catalysts, non-platinum-based catalysts, or mixtures thereof, which are known to act as catalysts in oxidation reactions (e.g., oxidation of hydrogen) or reduction reactions (e.g., reduction of oxygen) that occur in fuel cells. Typical examples of platinum-based catalysts include platinum catalysts, alloy catalysts between platinum and precious metals (Au, Ag, Pd, Ru, Rh, Ir, Os, etc.), alloy catalysts between platinum and non-precious metals (Ni, Fe, Co, Cr, Cu, Mn, V, Ti, Ta, Nb, Mg, Sn, Bi, Pb, Al, Mo, Nb, Ta, Zr, Ru, Se, etc.), alloy catalysts between platinum, precious metals, and non-precious metals, composite catalysts of platinum-based metals and metal oxides, and core-shell catalysts of transition metal cores and platinum shells. Typical examples of non-platinum catalysts include, but are not limited to, non-platinum alloy catalysts such as Ru-Ir alloys and Pd-transition metal alloys, transition metal (Ni, Fe, etc.)-N catalysts, and transition metal (Ni, Fe, etc.)-NC catalysts.

[0053] The catalyst material supported on the porous carbon body can be in the form of nanoparticles, and as a specific example, it can be particulate with a size of 0.5 nm to 4 nm, but is not limited to this.

[0054] The catalyst may contain 5 to 70% by weight, specifically 10 to 60% by weight, of the catalytic substance, but the present invention is not limited by the amount of catalytic substance supported.

[0055] The present invention includes a fuel cell catalyst layer containing the above-described porous carbon material.

[0056] A fuel cell catalyst layer according to one disclosure may include the above-mentioned porous carbon body, a catalyst material supported on the porous carbon body, and an ionomer.

[0057] The present invention includes a catalyst layer for a fuel cell containing the above-described catalyst.

[0058] A catalyst layer for a fuel cell according to one disclosure may include the above-mentioned catalyst and ionomer.

[0059] The ionomer can be any polymeric material known to conduct ions involved in the fuel cell reaction. Specifically, the ionomer can be a hydrogen ion-conducting ionomer. Examples of hydrogen ion-conducting ions include known sulfonated block copolymers, perfluorinated polymers having sulfonate groups on their side chains, or sulfonated aromatic polymers. Commercial ionsomers may be used, and examples of such commercial products include Nafion® (manufactured by DuPont), Aciplex® (manufactured by Asahi Kasei Corporation), and FLEMION® (manufactured by Asahi Glass Co., Ltd.).

[0060] The amount of catalyst contained in the catalyst layer may be as long as the desired catalytic activity is stably achieved during the electrochemical reaction of the fuel cell, but the amount of catalyst typically contained in a fuel cell catalyst layer is sufficient. As a practical example, the catalyst layer may contain 10 to 90% by weight, specifically 30 to 90% by weight, of the catalyst described above, but the present invention is not limited by the specific catalyst content in the catalyst layer.

[0061] If necessary, the catalyst layer may further contain a carbon material along with the catalyst and ionomer described above. The carbon material may include the porous carbon material described above without the catalyst, particulate conductive carbon material, carbon material with one-dimensional nanostructures (e.g., carbon nanotubes and carbon fibers), carbon material with two-dimensional nanostructures (e.g., graphene, reduced graphene oxide, graphene oxide), or mixtures thereof.

[0062] The present invention includes a film-electrode assembly containing the catalyst layer described above.

[0063] A membrane-electrode assembly according to one disclosure may include an anode, a cathode, and an electrolyte membrane interposed between the anode and the cathode. The anode may include a first gas diffusion layer and a first catalyst layer, and the cathode may include a second gas diffusion layer and a second catalyst layer. In this case, the first catalyst layer of the anode and the second catalyst layer of the cathode may be positioned in contact with the electrolyte membrane.

[0064] At least one of the first catalyst layer and the second catalyst layer may contain the porous carbon material described above or the catalyst described above. Substantially, at least one of the first catalyst layer and the second catalyst layer may be the fuel cell catalyst layer described above.

[0065] If necessary, the anode and cathode may be further provided with a microporous layer between the gas diffusion layer and the catalyst layer for improved water repellency, but the present invention is not limited to the specific structure of the film-electrode junction.

[0066] The gas diffusion layer can be made of any material commonly used in the field of fuel cells. Typical examples of gas diffusion layers include, but are not limited to, polyethylene terephthalate and carbon paper, which have water-repellent properties.

[0067] The electrolyte membrane can be any known membrane that is commonly used in the field of fuel cells for the conduction of the desired ions. In practical terms, the electrolyte membrane can be a hydrogen ion conductive electrolyte membrane. Typical examples of hydrogen ion conductive electrolyte membranes include sulfonated block copolymers, perfluorinated polymers having sulfonate groups on the side chains, or sulfonated aromatic polymers. Typical examples of commercial products include Nafion® (manufactured by DuPont), Aciplex® (manufactured by Asahi Kasei Corporation), and FLEMION® (manufactured by Asahi Glass Co., Ltd.).

[0068] The present invention includes a fuel cell comprising the above-mentioned porous carbon body, the above-mentioned catalyst, the above-mentioned catalyst layer, or the above-mentioned membrane electrode assembly.

[0069] The present invention includes a fuel cell stack in which the above-described membrane electrode assembly is used as a unit cell, and a large number of unit cells are stacked. In this case, each stacked unit cell can be positioned between separators in which a flow channel is formed.

[0070] A fuel cell containing the above-mentioned porous carbon body, catalyst, or catalyst layer may be a polymer electrolyte fuel cell, a direct methanol fuel cell, a phosphoric acid fuel cell, an alkali fuel cell, a molten carbonate fuel cell, or a solid oxide fuel cell. However, the above-mentioned porous carbon body, catalyst, or catalyst layer is more useful in polymer electrolyte fuel cells, where more expensive catalyst materials are used and there is a greater demand for improved catalyst durability.

[0071] The present invention includes a method for producing the porous carbon body described above.

[0072] A method for producing a porous carbon body according to one disclosure includes the steps of: heat-treating a carbon matrix at 800 to 1200°C for 0.5 to 5 hours under a hydrogen atmosphere or vacuum to perform surface reduction treatment; adding and stirring a carbon matrix surface-reduced in dimethylformamide (DMF) and poly(4-vinyl pyridine; P4VP) having a molecular weight (Mn) of 1K to 80K to produce a mixed solution using dimethylformamide (DMF) as both a solvent and dispersion medium; separating the mixed solution into solid and liquid components and then drying it to produce a P4VP-carbon matrix composite; and heat-treating the dried P4VP-carbon matrix composite at 600 to 800°C for 3 to 8 hours under an inert gas atmosphere to produce a nitrogen-doped porous carbon body.

[0073] In the manufacturing method described in one disclosure, a surface reduction treatment is performed to remove oxygen-containing functional groups (functional groups containing oxygen) present on the surface of the carbon matrix before the carbon matrix and P4VP come into contact with each other via a dimethylformamide medium.

[0074] Polar oxygen-containing functional groups on the carbon matrix surface cause uneven adhesion of P4VP (adhesion to the carbon matrix surface), reducing the nitrogen doping amount in the ultimately produced porous carbon body and causing defects within the porous carbon body.

[0075] Therefore, before positioning P4VP on the carbon matrix surface using the nonpolar sites of P4VP, a surface reduction treatment step is performed to remove oxygen-containing functional groups located on the carbon matrix surface.

[0076] The surface reduction treatment step includes a step of heat treatment (reducing heat treatment) at 800-1200°C for 0.5-5 hours under a hydrogen atmosphere or vacuum. The hydrogen atmosphere can be a mixed gas atmosphere in which hydrogen and an inert gas (argon, nitrogen, helium, etc.) are mixed, and the mixed gas atmosphere can contain 5-20 volume% hydrogen. The reducing heat treatment can be performed in an atmosphere in which the hydrogen-containing mixed gas flows at 100-500 sccm. If the reducing heat treatment is performed under vacuum, the reducing heat treatment is 10 -5 ~10 -2 This can be done under a pressure of Pa.

[0077] After the surface reduction treatment step, the surface-reduced carbon matrix is ​​brought into contact with P4VP having a molecular weight (Mn) of 1K to 80K, using dimethylformamide, which is the solvent for P4VP and the dispersion medium for the carbon matrix, as a mediator.

[0078] P4VP contains both nonpolar sites and nitrogen-containing polar sites. The nonpolar sites of P4VP have a high affinity for the carbon matrix surface and can firmly bond to the carbon surface after carbonization, while the nitrogen-containing polar sites of P4VP can act as a dopant, doping the carbon matrix with nitrogen.

[0079] The molecular weight (Mn) of P4VP between 1K and 80K inhibits P4VP from acting as a polymeric binder, preventing the carbon matrix from aggregating with each other. Furthermore, P4VP with a molecular weight (Mn) between 1K and 80K is substantially difficult to penetrate into the pores of the carbon matrix, allowing for concentrated and selective nitrogen doping of the carbon matrix surface (the outermost surface of the carbon matrix, excluding the inner pore surfaces). Simultaneously, P4VP with a molecular weight (Mn) between 1K and 80K can bind uniformly and evenly to the carbon matrix surface (outermost surface) within the dimethylformamide medium, enabling uniform nitrogen doping of the carbon matrix surface.

[0080] Through previous experiments, we confirmed that even when the carbon matrix is ​​surface-reduced, the quality of nitrogen doping in the resulting porous carbon body is significantly affected by the contact environment (mediation of contact) between P4VP and the carbon matrix.

[0081] Because P4VP possesses both polar and nonpolar sites, when the contact environment (mediation medium) is a polar or nonpolar solvent, the polar and nonpolar parts of P4VP may aggregate, potentially forming micelles or aggregates. The formation of such micelles and aggregates can lead to more macroscopically heterogeneous nitrogen doping on the surface of the carbon matrix. Furthermore, if the contact environment contains acid, oxygen-containing functional groups may be regenerated on the surface of the carbon matrix that has undergone surface reduction treatment.

[0082] Dimethylformamide is the mediating medium (contact environment) for the contact between the surface-reduced carbon matrix and the molecular weight-controlled P4VP, and is the solvent for P4VP. Dimethylformamide possesses both appropriate levels of polarity and nonpolarity, allowing P4VP to maintain a linear structure and be uniformly positioned within the contact environment without forming micelles or aggregates. Through this, it can bind and position itself in a linear structure on the surface of the carbon matrix, and can bind and position itself uniformly throughout the surface of the carbon matrix. Furthermore, dimethylformamide ensures that P4VP exists within the contact environment at a size corresponding to the intended (controlled) molecular weight. Similar to P4VP with a large molecular weight exceeding 80K, P4VP that forms micelles or aggregates can also act as a binder, leading to aggregation of the carbon matrix. By ensuring that P4VP exists within the contact environment at a size corresponding to the intended molecular weight, aggregation of the carbon matrix by P4VP can be suppressed.

[0083] The weight ratio of P4VP to surface-reduced matrix carbon in the mixture can be 1:8 to 12, specifically 1:9 to 11. The aforementioned mixing ratio (weight ratio) is such that P4VP uniformly covers the surface of the matrix carbon and nitrogen doping can be achieved at a high concentration. In this case, the mixture can contain 80 to 95% by weight of surface-reduced matrix carbon, but is not necessarily limited to this. For homogeneous mixing and dispersion, ultrasound can be applied to the mixture at 50 to 150 W for 5 to 20 minutes.

[0084] Subsequently, the solid component can be recovered from the mixture using a conventional solid-liquid separation method to obtain a composite in which P4VP is coated on the surface of the carbon matrix. Specific solid-liquid separation methods include centrifugation, and the recovered composite can be dried at a temperature at which dimethylformamide readily volatilizes (for example, 50-200°C).

[0085] Subsequently, the dried composite can be subjected to carbonization heat treatment to produce a nitrogen-doped porous carbon body. The carbonization heat treatment can be carried out in an inert gas atmosphere (e.g., nitrogen, argon, helium, etc.) at a temperature of 600-800°C, specifically 650-750°C, for 3-8 hours.

[0086] The carbon matrix can be any carbon material that requires nitrogen doping, but considering the specific application, it is sufficient to use a carbon material whose physical properties, such as particle size and porosity, are suitable for that application. Considering its application as a fuel cell catalyst support, the carbon matrix should be 1-7 cm². 3 The carbon material may have a pore volume of 1 / g, an average pore size of 3-15 nm, and a crystal size of 2-10 nm, but is not necessarily limited to these characteristics.

[0087] The present invention will be specifically described below with reference to examples. However, it should be noted that the examples described below are merely illustrative and concretize the present invention and are not intended to limit the scope of the rights of the present invention. This is because the scope of the rights of the present invention is determined by the matters described in the claims and matters that can be reasonably inferred therefrom.

[0088] The physical and electrochemical properties described in the detailed description and claims were analyzed and measured by the methods specified in the analysis and measurement methods below.

[0089] Analysis and measurement methods Cumulative diameter distribution 0.01 g of the analyte was suspended in ethanol, and the prepared suspension was sonicated for 30 minutes. The cumulative volume diameter distribution was then measured using a laser diffraction particle size analyzer (S3500, MICROTRAC). The cumulative volume median diameter is D 50 This refers to the diameter at the point where the cumulative volume reaches 50% in the cumulative volume diameter distribution.

[0090] X-ray diffraction measurement The X-ray diffraction patterns of the analyte were obtained using an X-ray diffraction analyzer (RIGAKU, SmartLab SE) under the following measurement conditions, applying the ASTM D5357 standard:

[0091] 0.5g of analyte (powder), Cu Kα radiation, scan range of 10-70°, scan speed of 5.0° / min, scan step size of 0.03°.

[0092] In porous carbon materials, the crystal size was calculated using the following Scherrer equation.

[0093] crystalline size(nm)=(k·λ) / (β0·cosθ)

[0094] The crystalline size is calculated using k (shape factor) = 0.9, β0 = full width at half maximum (radian) of the (002) peak in the X-ray diffraction pattern of a porous carbon material, λ = X-ray wavelength (nm), and θ = diffraction angle of (002) (Bragg angle, radian). The crystalline size corresponds to Lc.

[0095] Zeta potential The zeta potential of the analyte was measured according to ISO 13099-2 (Colloidal Systems - Methods for Zeta-potential Determination - Part 2: Optical Methods), using a zeta potential analyzer (Photal OTSUKA ELECTRONICS, ELSZ-2000ZS) under the following measurement conditions: 1) Add 1 g of the analyte to 50 ml of ethanol (ethyl alcohol, purity 99.5% or higher) and mix. Then, prepare a dispersion by ultrasonic stirring at a frequency of 40 kHz and an output of 100 W for 10 minutes. 2) Take a sample from the prepared dispersion and measure the electrophoretic mobility using a laser wavelength of 664.50 nm at a measurement temperature of 25°C. 3) Calculate the zeta potential from the electrophoretic mobility using the Huckel(u with umlaut) equation. 4) Repeat steps 1-3) three times, and the average value of the zeta potential is taken as the zeta potential of the analyte.

[0096] Specific surface area and mean pore size Experimentally, nitrogen adsorption / desorption isotherms were measured according to ASTM D6556. For details, the preparation of the sample for obtaining nitrogen adsorption / desorption isotherms in addition to ASTM D6556 was as follows: 1) Weigh 300 mg of the analyte (sample), 2) Dry the sample under a vacuum of 0.1 Torr or less and at 200°C for 12 hours. 3) Nitrogen adsorption / desorption isotherms were measured using a specific surface area measuring device (Micromeritics, ASAP 2460).

[0097] The measurement conditions for obtaining nitrogen adsorption / desorption isotherms in addition to ASTM D6556 are as follows: Nitrogen adsorption gas, liquid nitrogen at a temperature of 77K, relative pressure (P / P0) measurement accuracy of 0.02, relative pressure (P / P0) range of 0 to 1.

[0098] Using the BET method in nitrogen adsorption isotherms, the BET specific surface area (m²) 2 The value per gram ( / g) was calculated.

[0099] Using the BJH method, the relative nitrogen pressure (P / P0) of the adsorption / desorption isotherm is converted to the pore size (nm), and the amount of nitrogen adsorbed (cm²) is converted to the nitrogen adsorption amount (cm²). 3 ( / g STP) to stomatal volume (cm³) 3 By converting to ( / g), the stomatal size distribution, stomatal volume, and mean stomatal size were obtained. When converting relative pressure to stomatal size, a correction was made using the Harkins and Jura thickness curve. In addition, the Faas correction, which is the standard BJH correction, was also applied along with the Harkins and Jura thickness curve.

[0100] X-ray photoelectron spectroscopy X-ray photoelectron spectroscopy (XPS) was performed using an XPS analyzer (Thermo VG Scientific, K-alpha). Al-Kα rays, monochromatized using a monochromator, were used, and the analysis point size was 100 μm. The measured XPS data were processed with Thermo Avantage software, and background signals were removed using the Shirly method.

[0101] For the N 1s XPS spectrum, waveform separation was performed using four peaks: pyridic nitrogen binding (398.5±0.3eV), pyrolic nitrogen binding (400.4±0.3eV), graphitic nitrogen binding (401.0±0.3eV), and NO binding (402.0~405.0eV). Waveform separation (deconvolution) was then performed by fitting with a Gaussian function.

[0102] For the O 1s XPS spectrum, waveform separation was performed using three peeps: the carbon-oxygen single bond (O1) CO bond (533.5±0.5eV), the carbon-oxygen double bond (O2) C=O bond (532.2±0.5eV), and physicoadsorbed oxygen (>534.0). The waveform separation was then performed by fitting with a Gaussian function.

[0103] The oxygen content (at%) and nitrogen content (at%) of the analyzed substance were calculated using Thermo Avantage software.

[0104] Catalyst manufacturing Using the porous carbon material or matrix carbon produced in the examples and comparative examples as a support, 0.75 g of the support was dispersed in 388.2 g of a mixture of ethylene glycol (EG) and water (water:EG weight ratio = 1:1) to prepare a dispersion. Then, 4.95 g of a 20 wt% aqueous solution of platinum precursor was added to the prepared dispersion to prepare a mixed solution. The prepared mixed solution was heated at 105°C for 1 hour to support the platinum particles on the porous carbon material. After that, the mixed solution was cooled to room temperature, the porous carbon material with the supported platinum particles was filtered, thoroughly washed with distilled water, and dried in a vacuum dryer at a temperature of 250°C to produce a catalyst.

[0105] Manufacturing of catalyst-coated membranes (CCMs) Membrane electrode assemblies (MEAs) have an active area of ​​25 cm². 2 A catalyst-coated membrane (CCM) was prepared using the following method. In all tests, a commercial Pt / C (manufacturer TANAKA, product number 1021-E941, Pt catalyst loading amount 19.9%) was used as the oxidation electrode (anode) catalyst, and the catalyst prepared using the porous carbon material produced in the examples and comparative examples as the active reduction electrode (cathode) catalyst was used. All catalyst slurries were prepared by mixing the catalyst with distilled water, Nafion (20 wt% in DI water + 1-propanol ratio 0.739%), and 1-propanol. The prepared catalyst slurry was coated onto an FPI (fluorinated polyimide) film using a bar coater at a constant speed of 15 mm / sec. This film was dried at 60°C for 12 hours to produce a reduction electrode. The reduction electrode thus produced was pressed together with the commercial oxidation electrode and the Nafion film using a vacuum press at 145°C for 15 minutes to finally produce a CCM.

[0106] Electrochemical single cell evaluation: Electrochemical performance PEMFC performance was tested at 80°C. For initial electrochemical performance testing, low-humidification (40% relative humidity) high-purity hydrogen was supplied to the oxidation electrode, and low-humidification (40% relative humidity) air was supplied to the reduction electrode. In the low-humidification test, the minimum flow rate of high-purity hydrogen was 100 sccm, and the minimum flow rate of air was 200 sccm. During the performance test, the Stoichiometry Ratio (SR) was set to H2 / Air = 1.5 / 1.8, and the back pressure was maintained at 1.5 bar. The initial electrochemical performance was 0.8 A / cm². 2 The voltage measured under fixed current density conditions was used as the reference.

[0107] Electrochemical single cell evaluation: ESCA The electrochemical surface area (ECSA) was evaluated via Cyclic Voltammetry (CV) at 0.05V under 100 sccm of highly humidified (100% relative humidity) high-purity hydrogen. RHE from 1.05V RHE Measurements were taken at a sweeping rate of 50 mV / s. ECSA was calculated using a hydrogen desorption area of ​​0.05–0.4 VRHE, with a charge density per unit area of ​​platinum of 210 μC / cm². 2 This was used as the standard.

[0108] Electrochemical single cell evaluation: Degradation rate The electrochemical performance and ECSA degradation rate of the catalyst were evaluated according to the U.S. Department of Energy's (DOE) Accelerated Stress Test (AST) protocol. The durability test was conducted at 0.6–0.95V. RHE The test was conducted over 30,000 cycles within the specified voltage range, with a performance degradation rate of 0.8 A / cm². 2 The voltage drop measured under fixed current density conditions was used as the reference for calculation. The ECSA degradation rate was calculated by comparing the ECSA values ​​before and after the durability test.

[0109] (Manufacturing example) Molecular weight-adjusted poly(4-vinylpyridine) (P4VP) P4VP with controlled molecular weight was synthesized using known methods, employing 4VP (4-Vinylpyridine, 97%, Sigma-Aldrich), AIBN (2,2'-azobis(2-methylpropionitrile, 98%, Daejung), and 2(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester (98%, Sigma-Aldrich) as monomers, initiators, and chain transfer agents (CTAs), respectively.

[0110] In detail, 4VP was dissolved in THF (Tetrahydrofuran) containing recrystallized AIBN and a chain transfer agent (CTA), and then nitrogen purging was performed for 15 minutes to remove oxygen. The reaction mixture from which oxygen had been removed was sealed and heated in an oil bath at 70°C with continuous stirring for 6 hours to synthesize P4VP. After the reaction was complete, P4VP was precipitated, recovered, and dried. At this time, the molecular weight of P4VP was controlled by adjusting the ratio of 4VP to CTA in the reaction mixture. As an example, P4VP with a molecular weight of 10K was produced by adjusting the ratio of 4VP to CTA to 100:1, and P4VP with a molecular weight of 40K was produced by adjusting it to 400:1.

[0111] Deuterated dimethylformamide (DMF-d7) was used as the solvent, and proton nuclear magnetic resonance (M / S) was measured using a 500 MHz spectrometer (JNM-ECZ500R / S1, Jeol, Japan). 1 We performed 1H NMR spectroscopy to confirm that P4VP had been synthesized. 1Based on 1H NMR analysis, the ratio of monomer units multiplied with the RAFT agent was measured and converted to the average molecular weight to calculate the molecular weight. Through this, it was confirmed that P4VP with molecular weights of 5K (Production Example 1), 10K (Production Example 2), 30K (Production Example 3), 40K (Production Example 4), and 60K (Production Example 5) could be produced. The P4VP with a molecular weight of 160K used in Comparative Example 1 was commercial P4VP (Sigma-Aldrich). In this case, the molecular weight is the number-average molecular weight (Mn), in units of g / mol, and the K indicated with the number when reporting the molecular weight is 10 3 It means...

[0112] (Examples 1-5) Specific surface area is 594.54 m² 2 The value is / g, and the stomatal volume is 1.31 cm³. 3 A carbon matrix with a density of / g, an average pore size of 7.80 nm, a crystal size of 3.33 nm, an oxygen content of 2.66 at%, and an oxygen content of 19.1% in O2 bonds was used as the doped carbon matrix 1. The zeta potential of matrix carbon 1 was -59.17 mV.

[0113] The base carbon 1 was heat-treated at 900°C for 3 hours in an atmosphere where a hydrogen-argon mixed gas containing 20% ​​hydrogen by volume flowed at 300 sccm, thereby performing a surface reduction treatment.

[0114] P4VP: A mixture was prepared by adding surface-reduced matrix carbon to DMF (Dimethyl Formamide) and mixing it so that the weight ratio of the matrix carbon was 1:10, followed by ultrasonic dispersion treatment at 40 kHz and 100 W for 10 minutes. The concentration of matrix carbon in the mixture was 90 wt%.

[0115] The ultrasonically dispersed mixture was centrifuged at 5000 rpm for 90 minutes to recover the solid component (P4VP-matrix carbon composite). The recovered solid component was dried in a 90°C oven for 10 hours, and then the dried solid component was heat-treated in an argon atmosphere at 700°C for 5 hours to produce a nitrogen-doped porous carbon body.

[0116] Example 1 is an example in which a 60K molecular weight P4VP was used when preparing the mixed solution; Example 2 is an example in which a 40K molecular weight P4VP was used when preparing the mixed solution; Example 3 is an example in which a 30K molecular weight P4VP was used when preparing the mixed solution; Example 4 is an example in which a 10K molecular weight P4VP was used when preparing the mixed solution; and Example 5 is an example in which a 5K molecular weight P4VP was used when preparing the mixed solution.

[0117] (Example 6) Specific surface area is 1107.51 m² 2 The value is / g, and the stomatal volume is 2.39 cm³. 3 A carbon matrix with a density of / g, an average pore size of 7.32 nm, a crystal size of 2.25 nm, an oxygen content of 1.75 at%, and an oxygen content of 14.5% in O2 bonds was used as the doping matrix carbon 2. The matrix carbon 2 had a zeta potential of -55.08 mV.

[0118] Using matrix carbon 2 instead of matrix carbon 1, a nitrogen-doped porous carbon body was produced by surface reduction treatment, preparation of a mixed solution using 40K molecular weight P4VP, and carbonization treatment, similar to Example 2 (an example using 40K molecular weight P4VP).

[0119] (Example 7) Specific surface area is 707.58 m² 2 The value is / g, and the stomatal volume is 2.91 cm³. 3 A carbon matrix 3 was used as the doping target, with a density of 1 / g, an average pore size of 10.08 nm, a crystal size of 2.81 nm, an oxygen content of 1.89 at%, and an oxygen content of 14.5% of the total oxygen being O2 bonded. The zeta potential of the target carbon matrix 3 was -52.21 mV.

[0120] Using parent carbon 3 instead of parent carbon 1, a nitrogen-doped porous carbon body was produced by surface reduction treatment, preparation of a mixed solution using 40K molecular weight P4VP, and carbonization treatment, similar to Example 2 (an example using 40K molecular weight P4VP).

[0121] (Comparative Example 1) In Example 1, a nitrogen-doped porous carbon body was produced in the same manner as in Example 1, except that a commercially available 160K molecular weight P4VP (Sigma-Aldrich) was used instead of a 60K molecular weight P4VP during the preparation of the mixture.

[0122] (Comparative Example 2) A nitrogen-doped porous carbon body was produced in the same manner as in Example 1, except that after surface reduction treatment in Example 1, melamine was used instead of P4VP to prepare the mixture.

[0123] (Comparative Example 3) A nitrogen-doped porous carbon body was produced in the same manner as in Example 6, except that after surface reduction treatment in Example 6, melamine was used instead of P4VP to prepare the mixture.

[0124] (Comparative Example 4) In Example 2 (an example using P4VP with a molecular weight of 40K), a nitrogen-doped porous carbon body was produced in the same manner as in Example 2, except that a 0.1 M aqueous hydrochloric acid solution was used instead of DMF during the preparation of the mixed solution.

[0125] (Comparative Example 5) In Example 2 (an example using P4VP with a molecular weight of 40K), a nitrogen-doped porous carbon body was produced in the same manner as in Example 2, except that ethanol was used instead of DMF during the preparation of the mixture.

[0126] (Comparative Example 6) In Example 2 (an example using P4VP with a molecular weight of 40K), a nitrogen-doped porous carbon body was produced in the same manner as in Example 2, except that toluene was used instead of DMF during the preparation of the mixture.

[0127] (Comparative Example 7) In Example 2 (an example using P4VP with a molecular weight of 40K), a nitrogen-doped porous carbon body was produced in the same manner as in Example 2, except that the surface reduction treatment of the base carbon 1 was not performed and the mixture was prepared using the base carbon 1.

[0128] The cumulative volume median diameter (D) of the porous carbon bodies produced in Examples 1-5 and Comparative Examples 1-3, starting with base carbon 1. 50 The matrix carbon was as follows: Example 1: 3.14 μm, Example 5: 4.45 μm, Example 4: 5.29 μm, Example 3: 5.35 μm, Example 2: 5.50 μm, Example 1: 6.09 μm, Comparative Example 1: 7.54 μm, and Comparative Example 2: 5.51 μm.

[0129] From the results of the parent carbon 1, Examples 1-5, and Comparative Example 1, it was found that the binder effect of P4VP becomes stronger as the molecular weight of P4VP increases, and the D of the porous carbon body produced 50 It can be seen that the amount increases. Furthermore, from the results of Comparative Example 2, it can be seen that in the case of melamine, vigorous aggregation occurred on its own, and it acted as a binder that bound and aggregated the parent carbon atoms.

[0130] Table 1 shows the specific surface area (SSA, m²) of the porous carbon materials (nitrogen-doped porous carbon materials) produced in Examples 1-7 and Comparative Examples 1-7. 2 ( / g), Pore Volume, cm 3 This summarizes the mean pore size (pore width, nm) and crystal size (L, nm).

[0131] [Table 1]

[0132] The results from Examples 1-7 in Table 1 show that the porosity structure of the host carbon was substantially maintained almost unchanged through surface reduction treatment of the host carbon, control of the molecular weight of P4VP, and contact environment with dimethylformamide, and that nitrogen doping was applied to the surface of the host carbon. Furthermore, the results from Example 2 and Comparative Example 7 show that when surface reduction treatment of the host carbon is not performed, the P4VP near the surface aggregates due to the polar functional groups present on the surface of the host carbon upon contact with P4VP, and a porous carbon body equivalent to that of Comparative Example 1, where substantially 160K P4VP was used, is produced. In the case of Comparative Example 4, where acid is present in the contact environment, a porous carbon body with a smaller specific surface area and pore volume than that of Comparative Example 7 is produced. These results support the idea that, in order for linear P4VP to uniformly bond to the surface of the host carbon without aggregation of P4VP, it is advantageous to remove as many polar functional groups as possible from the surface of the carbon host upon contact with P4VP.

[0133] Table 2 shows the zeta potential (ζ, mV) and nitrogen content (N) of the porous carbon bodies (nitrogen-doped porous carbon bodies) produced in Examples 1-7 and Comparative Examples 1-7. tot %, at%), the percentage of total nitrogen contained in the manufactured porous carbon material that is in a pyridic N-bonded state (N1, %), the percentage of total nitrogen contained in the manufactured porous carbon material that is in a pyroric N-bonded state (N2, %), the ratio of the percentage of nitrogen in a pyridic N-bonded state to the percentage of nitrogen in a pyroric N-bonded state (N1 / N2, dimensionless), the oxygen content contained in the porous carbon material (O tot , at%), the ratio of nitrogen content to oxygen content in a porous carbon material (N tot / O tot This represents the dimensionless (O2) and the percentage (O2, %) of oxygen containing O2 bonds among the total oxygen contained in a porous carbon material.

[0134] [Table 2]

[0135] It was found that the porous carbon bodies produced in Examples 1-7 have a positive zeta potential. It was also found that porous carbon bodies with a negative zeta potential are produced in contact environments with acid (Comparative Example 4), polar solvents such as ethanol (Comparative Example 5), nonpolar solvents such as toluene (Comparative Example 6), and parent carbon that has not undergone surface reduction treatment (Comparative Example 7). Furthermore, it was found that when parent carbon is surface-reduced and used with P4VP with a molecular weight of 40K or less in a DMF contact environment, the zeta potential increases significantly to 10mV or more, and the nitrogen doping amount also increases significantly to 1at% or more.

[0136] Furthermore, when surface-reduced matrix carbon is brought into contact with P4VP with controlled molecular weight in a DMF contact environment, it was found that the proportion of nitrogen in a pyridic N-bonded state and nitrogen in a pyrolic N-bonded state of total nitrogen increased significantly to over 60%. The ratio of nitrogen in a pyridic N-bonded state to nitrogen in a pyrolic N-bonded state (N1 / N2) falls within the range of 1 to 2.5, indicating that the surface of the porous carbon body can exhibit both high affinity (strong bonding force) to catalytic materials and high affinity to ionomers.

[0137] When examining the oxygen and nitrogen content of the porous carbon materials produced in the examples and comparative examples, it can be seen that the porous carbon material produced in the examples has a surface richer in nitrogen than oxygen. In contrast, the porous carbon material produced in the comparative example has a nitrogen content of less than 1. tot / O tot The presence of a value indicates that oxygen is more abundant than nitrogen.

[0138] Furthermore, the porous carbon material produced in the examples not only contains a trace amount of oxygen (less than 1 at%), but also has a high proportion of stable O2-bonded oxygen (over 20%), indicating that the durability of the porous carbon material can be improved.

[0139] In Comparative Example 7, where no surface reduction treatment was performed, the polar functional groups present on the surface of the host carbon prevented the formation of a uniform nonpolar attraction between the carbon and P4VP. This resulted in the uneven aggregation of P4VP on the carbon surface, which is interpreted as acting as a binder. Furthermore, in the contact environment where acid is present (Comparative Example 4), polar functional groups were generated on the carbon surface in the mixed solution, resulting in a low N tot / O totThe values ​​indicate that the aggregation and micelle formation of P4VP on the carbon surface occurs due to such polar functional groups and the polar solvent water, resulting in heterogeneous nitrogen doping and aggregation of the parent carbon. In contact environments with polar solvents such as ethanol and toluene, and nonpolar solvents (Comparative Examples 5 and 6), P4VP micelles were formed in both cases, and it was found that these micelles promote binder action, leading to heterogeneous nitrogen doping. In particular, in contact environments with nonpolar solvents, micelles with nitrogen functional groups located internally are formed, further reducing nitrogen doping efficiency. When single molecules of melamine were used (Comparative Examples 2 and 3), it was interpreted that the oxygen content contained in the porous carbon body increased due to oxygen in the form of impurities contained in melamine, such as cyanic acid produced by the oxidation of melamine (melamine oxide, melamine resinol, etc.) or hydrolysis of melamine, and because there were no nonpolar portions, the nitrogen doping efficiency was poor due to weak interaction with the carbon surface. Furthermore, when melamine is used, although the nitrogen content with N1 bonds is high, the nitrogen content with N2 bonds is low, which is interpreted as poor initial performance during electrochemical evaluation (see the physical property evaluation results for Comparative Examples 2 and 3 in Table 3). In addition, when melamine is used, the interaction between melamine and carbon itself is small, and the binding force between the nitrogen doping site and the carbon skeleton in the porous carbon body is weak, so even if the nitrogen content with N1 bonds is high, the improvement in catalyst durability is not significant (see the physical property evaluation results for Comparative Examples 2 and 3 in Table 3). In the case of Comparative Example 1 using 160K P4VP, it was found that aggregation of P4VP itself occurs due to the high molecular weight and size of P4VP, resulting in non-uniform nitrogen doping and a decrease in nitrogen doping efficiency, and the specific surface area of ​​the porous carbon body also decreases due to the binder effect caused by aggregation.

[0140] Table 3 shows the 0.8 A / cm² values ​​for catalysts produced by loading platinum onto porous carbon bodies in the examples and comparative examples. 2 Initial voltage value at fixed current density (V@0.8A / cm 2 Voltage degradation rate (V) and voltage degradation rate at fixed current density (degradation rate @ 0.8 A / cm²) 2%, %, initial electrochemical specific surface area (ESCA, m 2 / g Pt This summarizes the degradation rate of electrochemical specific surface area (ESCA degradation rate, %).

[0141] [Table 3]

[0142] In Table 3, 0.8 A / cm 2 The initial voltage value at a fixed current density indicates the initial electrochemical performance of the catalyst, and the degradation rate is @0.8A / cm 2 This indicates the performance degradation rate of the catalyst. When examining the initial performance and performance degradation rate of examples using the same carbon matrix (Examples 1-5, Comparative Examples 1-2 and 4-7 / Example 6 and Comparative Example 3), it can be seen that porous carbon bodies with a positive zeta potential show significantly improved initial performance and a significantly lower performance degradation rate. Furthermore, when examining the ESCA and ESCA degradation rate of examples using the same carbon matrix (Examples 1-5, Comparative Examples 1-2 and 4-7 / Example 6 and Comparative Example 3), it can be seen that although the initial ESCA values ​​are similar to each other, porous carbon bodies with a positive zeta potential show a significantly lower ESCA degradation rate.

Claims

1. A porous carbon material for fuel cell catalyst support, containing 0.50 to 5.00 at% nitrogen and having a zeta potential of 0 mV or higher.

2. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the zeta potential of the porous carbon material is 1.00 to 50.00 mV.

3. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the ratio of nitrogen in a pyridinic N bond state to nitrogen in a pyrrolic N bond state among the total nitrogen contained in the porous carbon material is 1.0 to 3.

5.

4. The porous carbon material for fuel cell catalyst support according to claim 1, wherein of the total nitrogen contained in the porous carbon material, the proportion of nitrogen in a pyridinic N bonded state is 40% or more, and the proportion of nitrogen in a pyrrolic N bonded state is 20% or more.

5. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the oxygen content of the porous carbon material is 1.5 at% or less.

6. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the porous carbon material contains oxygen, and the ratio of the nitrogen content (at%) contained in the porous carbon material to the oxygen content (at%) is 1.0 to 5.

0.

7. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the proportion of oxygen having O2 bonds in the total oxygen contained in the porous carbon material is 20% or more.

8. The pore volume of the porous carbon material is 0.5 to 5.0 cm³. ３ A porous carbon body for fuel cell catalyst support according to claim 1, wherein the amount is / g.

9. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the average pore size of the porous carbon material is 3 to 20 nm.

10. The porous carbon material for fuel cell catalyst support according to claim 1, wherein the crystal size calculated from the X-ray diffraction pattern of the porous carbon material is 2.0 to 5.5 nm.

11. The cumulative volume median diameter (D) of the porous carbon body ５０ The porous carbon body for fuel cell catalyst support according to claim 1, wherein the diameter is 0.1 to 12 μm.

12. A fuel cell catalyst comprising a porous carbon body according to any one of claims 1 to 11.

13. A catalyst layer for a fuel cell containing the catalyst and ionomer described in claim 12.

14. A fuel cell comprising the catalyst according to claim 12.

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