Porous carbon support and catalyst for fuel cells

Abstract

The present disclosure relates to a porous carbon body, and more particularly to a porous carbon body that satisfies three physical properties, including a surface area property for pores having a size of 2 nm or more and 5 nm or less, a surface area property for pores having a size of 2 nm or more and 100 nm or less, and a property on a delta graph, which is a graph of nitrogen adsorption / desorption isotherms obtained by subtracting the value of the nitrogen adsorption isotherm from the value of the nitrogen desorption isotherm as a function of relative pressure.

Description

[Technical Field]

[0001] The present disclosure relates to a porous carbon support and a fuel cell catalyst using the same.

[0002] The national research and development projects that supported this invention are as follows: Project unique number 1711182201 Project number: 2021M3H4A1A02049886 Ministry of Science, ICT and Communication Name of the project management (specialized) organization: Korea Research Foundation Research project name: Nanomaterial technology development / leading type Title of research project: Development of synthesis technology for highly crystalline porous carbon supports based on low-temperature processes Contribution rate 0.5 Project execution organization name: The Carbon Studio Co., Ltd. Research period: 2023-01-01~2023-12-31

[0003] Project unique number 1415186363 Project number 20020437 Ministry of Trade, Industry and Energy Issue Management (Specialized) Agency Name Korea Institute for Industrial Technology Planning and Evaluation Research project name: Nano-fusion innovative product technology development Research title: Development of fuel cell module technology for hydrogen electric vehicles based on platinum alloy nanocatalyst production with MEA platinum usage of 0.2gkW or less Contribution rate 0.5 Project execution organization name: The Carbon Studio Co., Ltd. Research period: 2023-01-01~2023-12-31 [Background technology]

[0004] Polymer electrolyte membrane fuel cells (PEMFCs) have been attracting attention as an energy source that can replace fossil fuels, as they are highly energy efficient and environmentally friendly.

[0005] PEMFC is a power generation system that produces electricity through the electrochemical reaction of hydrogen and oxygen using a catalyst, and has a structure in which unit cells including a membrane-electrode assembly (MEA) and bipolar plates are stacked. The MEA has a structure in which a cation exchange membrane (also known as a polymer electrolyte membrane) is inserted into the anode and cathode.

[0006] An important factor that determines the performance of a fuel cell is the catalyst used to form the electrodes (anode and cathode) of the MEA, which is generally a porous carbon support carrying platinum-based catalyst particles.

[0007] Porous carbon supports not only support catalyst particles but also affect catalytic performance. For example, the specific surface area of ​​the carbon support determines the amount of catalyst particles supported, and the degree of deterioration of the carbon support affects the stability and durability of the entire fuel cell. Above all, the pore structure of the carbon support has a significant impact on the degree of dispersion of the supported catalyst particles, the size of the catalyst particles, the position of the catalyst particles within the support, gas diffusion, the degree of flooding, and power generation performance depending on fuel cell operating conditions (e.g., high temperature and low humidity conditions). Therefore, extensive research is being conducted to control the size and structure of the pores of the carbon support.

[0008] However, there are still various interpretations, including contradictory interpretations, regarding the advantageous pore structure of a porous carbon support, and the advantageous pore structure has not yet been established. Summary of the Invention [Problem to be solved by the invention]

[0009] One aspect of the present disclosure is to provide a porous carbon body that can exhibit improved mass activity when utilized as a catalyst support in a fuel cell.

[0010] The object of the present invention is not limited to the above-mentioned content, and a person having ordinary skill in the art to which the present invention pertains will have no difficulty in understanding further object of the present invention from the entire contents of the specification of the present invention. [Means for solving the problem]

[0011] The porous carbon body according to one disclosure satisfies the following physical properties: Physical property 1: The surface area of ​​pores with a size of 2 to 5 nm obtained by the nitrogen desorption isotherm based on the BJH (Barrett-Joyner-Halenda) method based on the Harkins-Jura equation is 100 m 2 / g~500m 2 / g, Physical property 2: The surface area of ​​pores between 2 nm and 100 nm in size obtained by the nitrogen desorption isotherm based on the BJH method based on the Harkins-Jura equation is 200 m 2 / g~1500m 2 / g, Physical property 3: The nitrogen adsorption-desorption isotherm (N2 adsorption-desorption isotherm) has hysteresis, and the delta graph, which is a graph of the value obtained by subtracting the value of the nitrogen adsorption isotherm from the value of the nitrogen desorption isotherm as a function of relative pressure in the relative pressure range of 0.3 to 1.0, has at least a first maximum and a second maximum, and the value of the first maximum located at a lower relative pressure is less than the value of the second maximum located at a higher relative pressure.

[0012] In one specific example, the ratio of the first maximum value divided by the second maximum value may be 0.10 to 0.95.

[0013] In one specific example, the first maximum point may be located in a relative pressure (P / P0) range of 0.4 or more and less than 0.9, and the second maximum point may be located in a relative pressure (P / P0) range of 0.9 or more and less than 1.0.

[0014] In one specific example, the first maximum point may be located in a relative pressure (P / P0) range of 0.45 to 0.80, and the second maximum point may be located in a relative pressure (P / P0) range of 0.93 to 0.98.

[0015] In one specific example, in the nitrogen adsorption / desorption isotherm, the area ratio obtained by dividing the hysteresis area in the relative pressure (P / P0) range of 0.9 to 1.0 by the hysteresis area in the relative pressure (P / P0) range of 0.4 to 0.9 may be 0.1 to 2.0.

[0016] In one embodiment, the area ratio may be 0.1 to 1.5.

[0017] In one embodiment, the porous carbon body may further satisfy the following property 4: Physical Property 4: Average layer spacing (d 002 ) is 0.335nm~0.350nm.

[0018] In one embodiment, the porous carbon body may further satisfy the following properties: Physical Property 5: Lattice constant in the a-axis direction (L a ) is 4nm to 12nm.

[0019] In one embodiment, the relative pressure (P / P0) at which the hysteresis closes may be 0.45 or less.

[0020] In one specific example, in the delta graph, the value of a minimum point located between the first maximum point and the second maximum point may be 15 to 90% of the value of the first maximum point.

[0021] In one embodiment, the porous carbon body may be a porous carbon body doped with a different element.

[0022] A fuel cell catalyst according to one disclosure includes the porous carbon body described above and a catalytic material supported on the porous carbon body described above.

[0023] A catalyst layer for a fuel cell according to one disclosure contains the above-described catalyst and an ionomer.

[0024] The present invention includes a polymer electrolyte membrane fuel cell comprising the catalyst described above. [Effects of the Invention]

[0025] The porous carbon body according to one disclosure has a unique pore structure and can exhibit improved mass activity when utilized as a catalyst support in a fuel cell.

[0026] The porous carbon body according to one embodiment allows for smooth mass transfer of all reactants and products of a fuel cell due to its unique pore structure, and also allows for smooth transfer of protons, thereby exhibiting improved mass activity when used as a catalyst support for a fuel cell.

[0027] According to another embodiment, the porous carbon body has a unique pore structure, which allows it to have improved mass activity and high crystallinity, and thus exhibits improved durability when used as a catalyst support in a fuel cell.

[0028] The various yet significant advantages and effects of the present invention are not limited to the above, but can be more easily understood in the course of describing specific embodiments of the present invention. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a diagram showing a delta graph of a porous carbon body manufactured according to an embodiment. [Figure 2] 10 is a diagram showing a delta graph of a comparative sample. [Figure 3] 10 is a diagram showing a delta graph of a comparative sample. DETAILED DESCRIPTION OF THE INVENTION

[0030] The terms used herein are for the purpose of describing the present invention and are not intended to limit the present invention. Furthermore, as used herein, the singular forms also include the plural forms unless the relevant definition clearly indicates otherwise.

[0031] The meaning of "comprises" as used in the specification is to specify features and does not exclude the presence or addition of other features.

[0032] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Dictionary-defined terms are to be interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content.

[0033] In this specification and the appended claims, the terms "first," "second," etc. are not used in a limiting sense but only to distinguish one element from another.

[0034] In this specification and the appended claims, the term "fuel cell" may refer to a polymer electrolyte membrane fuel cell (PEMFC), a phosphoric acid fuel cell (PAFC), an alkaline fuel cell (AFC), a molten carbonate fuel cell (MCFC), or a solid oxide fuel cell (SOFC), etc. However, the porous carbon body according to one embodiment can exhibit improved mass activity when supporting a catalytic material, and thus can be more effectively used in fuel cells that typically use expensive catalytic materials. Examples of such fuel cells include a polymer electrolyte membrane fuel cell (PEMFC) and a phosphoric acid fuel cell (PAFC).

[0035] In this specification and the appended claims, pore size classification follows the definition of the International Union of Pure and Applied Chemistry (IUPAC). Specifically, according to the IUPAC definition, micropores refer to pores with a diameter of 2 nm or less, mesopores refer to pores with a diameter of 2 nm to 50 nm, and macropores refer to pores with a diameter of 50 nm or more.

[0036] In this specification and the appended claims, the nitrogen adsorption / desorption isotherm refers to an isotherm obtained by measuring the nitrogen adsorption of a porous carbon material, which is a combination of an isotherm of the nitrogen adsorption process (nitrogen adsorption isotherm) and an isotherm of the nitrogen desorption process (nitrogen desorption isotherm). The x-axis represents the nitrogen relative pressure (P / P0) and the x-axis represents the amount of nitrogen adsorption (cm 3 When viewed in detail as a graph with the y-axis of (p / g STP), a nitrogen adsorption / desorption isotherm refers to a graph having the same x-axis and y-axis, in which a nitrogen adsorption isotherm and a nitrogen desorption isotherm are shown together. Hysteresis can refer to the separation of the nitrogen adsorption isotherm and the nitrogen desorption isotherm from the nitrogen adsorption / desorption isotherm. In other words, hysteresis can refer to a certain region where the nitrogen adsorption amount is different at the same relative pressure due to differences in the nitrogen adsorption process and the nitrogen desorption process.

[0037] The present inventors conducted research into porous carbon materials for use as catalyst supports in fuel cells that satisfy both high porosity and high crystallinity, which are known to have a trade-off relationship. During this research, the inventors discovered that the relatively coarse pore structure, including mesopores and macropores, of porous carbon materials for use as catalyst supports in fuel cells significantly affects the mass activity of fuel cell catalyst materials. Based on this discovery, the inventors furthered their research and established a pore structure for a porous carbon material that can significantly improve the mass activity of catalyst materials, thereby completing the present invention.

[0038] A porous carbon body according to one disclosure based on the above-mentioned discovery satisfies the following properties 1, 2, and 3: Physical property 1: The surface area of ​​pores with a size of 2 to 5 nm obtained by the nitrogen desorption isotherm based on the BJH (Barrett-Joyner-Halenda) method based on the Harkins-Jura equation is 100 m 2 / g~500m 2 / g, Physical property 2: The surface area of ​​pores with sizes between 2 nm and 100 nm obtained by the nitrogen desorption isotherm based on the BJH method based on the Harkins-Jura equation is 200 m 2 / g~1500m 2 / g, Physical property 3: The nitrogen adsorption-desorption isotherm (N2 adsorption-desorption isotherm) has hysteresis, and the delta graph, which is a graph of the value obtained by subtracting the value of the nitrogen adsorption isotherm from the value of the nitrogen desorption isotherm as a function of relative pressure in the relative pressure range of 0.3 to 1.0, has at least a first maximum and a second maximum, and the value of the first maximum located at a lower relative pressure is less than the value of the second maximum located at a higher relative pressure.

[0039] The pore region having a size of 2 to 5 nm is the region that mainly affects the loading of the catalytic material, and the specific surface area of ​​the 2 to 5 nm pore region can determine the characteristics of the catalytic material loaded on the porous carbon body.

[0040] When the porous carbon body satisfies property 1, the catalyst material can be supported on the porous carbon body in the form of extremely fine particles of a few nanometers (for example, 1 to 3 nm), which can suppress aggregation of the catalyst material and improve the stability and durability of the catalyst.

[0041] According to one embodiment, the porous carbon body has a surface area of ​​100 m2 of pores with a size of 2 to 5 nm, as determined by a nitrogen desorption isotherm based on the Harkins-Jura-based Barrett-Joyner-Halenda (BJH) method. 2 / g~500m 2 / g, for details see 100m 2 / g~400m 2 / g, more specifically 100m 2 / g~350m 2 / g can be satisfied.

[0042] The pore region of 2 nm to 100 nm in size is involved in the movement of fuel cell reaction products such as water, and the specific surface area of ​​the pore region of 2 nm to 100 nm can affect various fuel cell characteristics. When the porous carbon body satisfies property 2, the reaction products of the fuel cell can be smoothly moved during operation.

[0043] In one embodiment, the porous carbon material has a surface area of ​​200m2 of pores with a size of 2 to 100 nm, as determined by a nitrogen desorption isotherm based on the Harkins-Jura-based BJH method. 2 / g~1500m 2 / g, details 200m 2 / g~1000m 2 / g, more specifically 200m 2 / g~800m 2 / g, and more specifically 200m 2 / g~700m 2 / g can be satisfied.

[0044] A porous carbon material according to one specific example can satisfy the above-mentioned property 1 and property 2, and at the same time, can satisfy the following property 3.

[0045] Physical property 3: The nitrogen adsorption-desorption isotherm (N2 adsorption-desorption isotherm) has hysteresis, and the delta graph, which is a graph of the value obtained by subtracting the value of the nitrogen adsorption isotherm from the value of the nitrogen desorption isotherm as a function of relative pressure in the range of relative pressure (P / P0) from 0.3 to 1.0, has at least a first maximum and a second maximum, and the value of the first maximum located at a lower relative pressure is less than the value of the second maximum located at a higher relative pressure.

[0046] As is known, the nitrogen adsorption / desorption isotherm shows the relationship between the nitrogen partial pressure and the amount of nitrogen adsorbed, and is the adsorption amount (cm) depending on the relative pressure (P / P0). 3The delta graph is a graph of the delta value (the value obtained by subtracting the adsorption amount value of the nitrogen adsorption isotherm from the adsorption amount value of the nitrogen desorption isotherm at each relative pressure). Therefore, similar to the nitrogen adsorption / desorption isotherm, the delta graph has the relative pressure (P / P0) on the x-axis and the cm 3 1 is a graph with the y-axis values ​​being the difference in adsorption (delta value) in / g STP.

[0047] The maximum point in the delta graph may correspond to a boundary point between an increasing region where the delta value increases as the relative pressure increases and a decreasing region where the delta value decreases as the relative pressure increases, and the increasing region and the decreasing region are of course continuous regions based on the boundary point.

[0048] Physical property 3 is a physical property related to the coarse pore structure, including mesopores and macropores, of a porous carbon body. In physical property 3, a delta graph having at least two maxima may mean that the porous carbon body has a pore structure in which at least two groups of coarse pores having different size categories have been developed. At the same time, a physical property in which the value of the second maximum, which is located at a relatively high relative pressure, is greater than the value of the first maximum, which is located at a relatively low relative pressure, may mean that the porous carbon body has a pore structure in which the group of coarse pores having a relatively larger size category among the two well-developed groups of coarse pores has been further developed.

[0049] When the porous carbon body satisfies property 3, gaseous reactants such as oxygen can be smoothly supplied into the porous carbon body, and at the same time, deterioration of fuel cell performance due to the flooding phenomenon in which pores are clogged with reaction products such as water can be prevented.

[0050] As described above, a delta graph can have a first increasing region and a first decreasing region with a boundary point at a first maximum point, and a second increasing region and a second decreasing region with a boundary point at a second maximum point.

[0051] In the delta graph, the first increasing region, the first decreasing region, the second increasing region, and the second decreasing region may be positioned sequentially in the direction of increasing relative pressure, and may be positioned consecutively with one another. "Positioned consecutively with one another" means that no intersections are formed between the delta graph and the x-axis except for the endpoints of the delta graph that are positioned at the relative pressures where the hysteresis closes.

[0052] The fact that the delta graph does not touch the x-axis except at the end points of the delta graph means that at least two groups of coarse pores having different size categories developed in the porous carbon body are connected (communicate) with each other.

[0053] Specifically, the value of the minimum point corresponding to the boundary between the first decrease region and the second increase region, or more specifically, the value of the minimum point located between the first maximum point and the second maximum point, is a positive real number, specifically 15 to 90% of the value of the first maximum point, more specifically 20 to 85% of the value of the first maximum point. A porous carbon material having such a minimum point on the delta graph may have a pore structure in which two coarse pore groups are well connected to each other through other pores, thereby facilitating and activating the movement of materials, including reactants and reaction products. Therefore, when used as a catalyst support for a fuel cell, a porous carbon material having such a minimum point may stably maintain fuel cell characteristics over a wide humidity range, from low to high humidity.

[0054] In one specific example, the relative pressure (P / P) at which the hysteresis loop of the nitrogen adsorption / desorption isotherm closes may be 0.45 or less, specifically 0.40 to 0.45, and more specifically 0.40 to 0.43. The hysteresis loop that closes at a relative pressure of around 0.4 indicates that the pores of the porous carbon material contain a certain amount of bottleneck pores.

[0055] In one specific example, the porous carbon body may have a delta graph in which the first maximum point is located in a range (region) of relative pressure (P / P) of 0.4 or more to less than 0.9, and the second maximum point is located in a range (region) of relative pressure (P / P) of 0.9 or more to less than 1.0.

[0056] When at least two well-developed groups of coarse pores are defined as a first group of coarse pores (pores that contribute to forming the first maximum point) and a second group of coarse pores (pores that contribute to forming the second maximum point), the position of each maximum point can indicate the size category of the pores that contribute to each group of coarse pores.

[0057] The first maximum point being located in a relative pressure range (region) of 0.4 to less than 0.9, specifically 0.45 to 0.80, means that the first coarse pore group is formed by pores that are larger than the particulate catalyst supported on the porous carbon body by a certain degree. These first coarse pore groups allow for smooth and rapid supply of gas to the particulate catalyst and smooth and rapid discharge of liquid from the particulate catalyst, effectively preventing flooding. Smooth mass transfer between the gas and liquid phases ensures high mass activity in the high current region.

[0058] Specific examples of the gas phase include gases involved in the electrochemical reaction of the fuel cell, such as oxygen, air, and hydrogen, and specific examples of the liquid phase include liquids containing the reaction products of the electrochemical reaction of the fuel cell, such as water, but the present invention is not limited by the specific substances in the gas phase and liquid phase.

[0059] The fact that the second maximum point is located in the relative pressure range (region) of 0.9 or more to less than 1.0, specifically the range (region) of 0.93 to 0.98, means that the second coarse pore group is formed by coarse pores of 100 nm or more. These second coarse pore groups enable strong bonding between the ion transfer mediator, such as an ionomer, and the porous carbon body, allowing at least a portion of the ion transfer mediator to be easily introduced into the porous carbon body, resulting in smooth ion migration to the particulate catalyst. The strong bonding with the ion transfer mediator and smooth ion migration characteristics enable high mass activity in the low- and medium-current ranges.

[0060] A specific example of the ions is hydrogen ions that are involved in the electrochemical reaction of a fuel cell, but the present invention is not limited to a specific type of ion.

[0061] As described above, the porous carbon body has a pore structure with a first maximum point located in the range of 0.4 to less than 0.9 on the delta graph, specifically in the range of 0.45 to 0.80, and a second maximum point located in the range of 0.9 to less than 1.0, specifically in the range of 0.93 to 0.98, on the delta graph. This allows for smooth movement of all of the gas phase, liquid phase, and ions, and when used as a catalyst support for a fuel cell, improved mass activity can be ensured over a wide current range, including low, medium, and high current ranges.

[0062] Furthermore, due to the minimum points having the above-mentioned sizes, the porous carbon body has good communication between the first group of coarse pores formed by pores larger than the particulate catalyst and the second group of coarse pores formed by coarse pores of 100 nm or more, which allows the three phases of gas, liquid, and ions to move more smoothly and quickly inside and between the inside and outside of the porous carbon body.

[0063] In one specific example, the maximum point ratio (M1 / M2), obtained by dividing the value of the first maximum point M1 on the delta graph by the value of the second maximum point M2, may be 0.10 to 0.95, specifically 0.15 to 0.90. When a porous carbon body has a pore structure that satisfies the above maximum point ratio, gas and ions can be uniformly and smoothly supplied from particulate catalyst material located in pore regions having pore sizes of 2 to 5 nm within the porous carbon body. Furthermore, when the above maximum point ratio is satisfied along with Property 1, Property 2, and Property 3, the gas and ion supply can be maximized.

[0064] In one specific example, in the nitrogen adsorption / desorption isotherm of the porous carbon body, the area ratio (HA2 / HA1) obtained by dividing the hysteresis area (HA2) in the relative pressure (P / P0) range of 0.9 to 1.0 by the hysteresis area (HA1) in the relative pressure (P / P0) range of 0.4 to 0.9 may be 0.1 to 2.0, specifically 0.1 to 1.5, and more specifically 0.10 to 1.3.

[0065] The hysteresis area (HA1) located in the relative pressure range of 0.4 to 0.9 can indicate the degree of development of pores contributing to the first coarse pore group, and the hysteresis area (HA2) located in the relative pressure range of 0.9 to 1.0 can indicate the degree of development of pores contributing to the second coarse pore group.

[0066] The above area ratio (HA2 / HA1) indicates that the first coarse pore group is formed of pores having a wide size range, and at the same time, the pores having a wide size range are uniformly and well developed.

[0067] A pore structure that satisfies the above-mentioned area ratio together with the first, second and third physical properties may, in particular, allow smooth and rapid movement of a liquid phase within the porous carbon body and discharge of the liquid phase from the inside to the outside.

[0068] In one embodiment, the porous carbon body is an aggregate of primary particles randomly aggregated together, and the primary particles may contain hollow particles. Therefore, the pore structure of the porous carbon body may be formed by pores in the primary particles themselves, between the primary particles, between portions of the aggregates and the primary particles, between portions of the aggregates, and between the aggregates.

[0069] The average primary particle diameter of the porous carbon material may be 10 nm to 30 nm. In this case, the average primary particle diameter may be measured according to ASTM D3849. 50 In this case, D 50 It can mean the size corresponding to 50% in the mass cumulative particle size distribution of the porous carbon body. 50can be obtained by subjecting a dispersion of the porous carbon material dispersed in a dispersion medium to ultrasonic treatment for 30 minutes, and then measuring the particle size distribution using a laser diffraction particle size distribution analyzer.

[0070] In one embodiment, the porous carbon body can further satisfy the following property 4.

[0071] Physical Property 4: Average layer spacing (d 002 ) is 0.335nm~0.350nm

[0072] The average layer spacing (d 002 ) is an index that directly indicates the crystallinity of the carbon that forms the porous carbon body. 002 can mean that the carbon nanotube is formed by a highly controlled, well-developed, coarse pore structure that satisfies properties 1, 2, and 3 and has excellent crystallinity.

[0073] The excellent crystallinity of the carbon skeleton allows the porous carbon material to have better oxidation resistance, and therefore, when the porous carbon material is used as a catalyst support in a fuel cell, the catalyst can have improved durability.

[0074] In addition to or independently of this, the porous carbon body may further satisfy the following property 5.

[0075] Physical Property 5: Lattice constant in the a-axis direction (L a ) is 4 nm to 12 nm, specifically 6 nm to 12 nm, more specifically 7 nm to 12 nm, and even more specifically 7.5 nm to 12 nm

[0076] Property 5 also relates to the crystallinity of the porous carbon material, and a larger La value indicates that the carbon skeleton of the porous carbon material is formed of graphite with broader hexagonal mesh planes. Having a porous carbon material satisfying property 5 is advantageous because it reduces the number of defect sites that are vulnerable to oxidation.

[0077] In addition to or independently of this, the porous carbon body may further satisfy the following physical property 6.

[0078] Physical Property 6: The average number of graphene layers calculated by X-ray diffraction is 6 to 20, specifically 7 to 15, more specifically 8 to 15

[0079] Property 6 is also related to the crystallinity of the porous carbon material, and the average number of graphite layers is determined by the lattice constant in the c-axis direction (L c ) to d 002 The average number of graphite layers is calculated by dividing the average number of graphite layers by the average number of graphite layers and adding 1 to the result. A larger average number of graphite layers indicates that the carbon skeleton of the porous carbon body is formed of thicker graphite crystals.

[0080] In an advantageous example, the porous carbon body may have the above-described pore structure and excellent crystallinity satisfying all of properties 4, 5, and 6. When the porous carbon body has the above-described pore structure and at the same time has crystallinity satisfying all of properties 4, 5, and 6, the porous carbon support may have excellent oxidation resistance, with a mass loss rate at 500°C to 700°C in thermogravimetric analysis (TGA) of 0% to 30%, specifically 2 to 28%, or 10 to 28%, or 15 to 25%, or 18 to 20%, or 21 to 23%.

[0081] Furthermore, when a porous carbon body has the above-described pore structure and at the same time has crystallinity that satisfies all of properties 4, 5, and 6, the temperature at which the mass of the porous carbon support is reduced by 30% based on the raw material in thermogravimetric analysis is a high temperature of 700°C to 740°C, specifically 705°C to 730°C, 710°C to 715°C, or 715°C to 725°C, and the oxidation resistance can be exhibited. Experimentally, thermogravimetric analysis of the porous carbon body can be measured according to ASTM E1131.

[0082] In one embodiment, the porous carbon body may be doped with a different element. The different element may include one or more elements selected from metalloids, nonmetals (excluding carbon), and transition metals. Metalloids may include one or more elements selected from B, Si, Ge, As, Sb, Te, and Po. Nonmetals may include one or more elements selected from N, O, P, S, and Se. The transition metal may include one or more elements selected from metals belonging to Groups 3 to 12, specifically, metals belonging to Periods 4 and 5 of Groups 3 to 12 (e.g., Co, Fe, Ni, Cu, Zn, Cr, V, Ti, Sc, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, and Cd) and metals belonging to the lanthanum group (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). When the porous carbon body is doped with a different element, the porous carbon body may contain 0.05 to 5.00 mass% of the different element. Specifically, the porous carbon body may contain 0.05 to 5.00 mass% of semimetals, 0.05 to 0.50 mass% of nonmetals, and / or 0.05 to 2.00 mass% of transition metals. Doping with different elements can improve catalytic activity when used as a catalyst support for a fuel cell.

[0083] The present invention includes a fuel cell catalyst comprising the porous carbon body described above.

[0084] A fuel cell catalyst according to one disclosure includes a support, which is the porous carbon body described above; and a catalytic material supported on the support.

[0085] The catalytic material may include platinum-based catalysts, non-platinum-based catalysts, or mixtures thereof that are known to catalyze oxidation reactions (e.g., hydrogen oxidation) or reduction reactions (e.g., oxygen reduction) occurring in fuel cells. Representative examples of platinum-based catalysts include platinum catalysts, alloy catalysts between platinum and noble metals (e.g., Au, Ag, Pd, Ru, Rh, Ir, Os), alloy catalysts between platinum and non-noble metals (e.g., Ni, Fe, Co, Cr, Cu, Mn, V, Ti, Ta, Nb, Mg, Sn, Bi, Pb, Al, Mo, Nb, Ta, Zr, Ru, Se), alloy catalysts between platinum, noble metals, and non-noble metals, composite catalysts of platinum-based metals and metal oxides, and core-shell catalysts with a transition metal core and a platinum shell. Representative examples of non-platinum catalysts include non-platinum alloy catalysts such as Ru-Ir alloys and Pd-transition metal alloys, transition metal (Ni, Fe, etc.)-N-based catalysts, transition metal (Ni, Fe, etc.)-NC-based catalysts, etc. However, the porous carbon materials described above are more advantageous for supporting platinum catalysts by providing a pore structure that is more effective for supporting catalytic materials having sizes on the order of clusters or several nanometers.

[0086] The catalyst material supported on the porous carbon body may be in the form of nanoparticles, and in one specific example, may be in the form of particles having a size on the order of 0.5 nm to 4 nm.

[0087] 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 the catalytic substance carried.

[0088] The present invention includes a catalyst layer for a fuel cell that contains the porous carbon body described above.

[0089] A catalyst layer for a fuel cell according to one embodiment of the present disclosure may include the porous carbon body described above, a catalyst material supported on the porous carbon body, and an ionomer.

[0090] The present invention includes a catalyst layer for a fuel cell containing the above-described catalyst.

[0091] A catalyst layer for a fuel cell according to one disclosure can include the above-described catalyst and an ionomer.

[0092] The ionomer may be any polymeric material known to conduct ions involved in the fuel cell reaction. Specifically, the ionomer may be a proton-conducting ionomer. Examples of proton-conducting ionomers include known sulfonated block copolymers, perfluorinated polymers with sulfonate groups on the side chains, and sulfonated aromatic polymers. Commercially available ionomers may be used. Examples of such commercial products include Nafion® (manufactured by DuPont), Aciplex® (manufactured by Asahi Kasei Corporation), and Flemion® (manufactured by Asahi Glass Co., Ltd.).

[0093] The content of the catalyst in the catalyst layer may be any amount that can stably realize the desired catalytic activity during the electrochemical reaction of the fuel cell, and may be any amount that is typically contained in the catalyst layer of a fuel cell. As a practical example, the catalyst layer may contain 10 to 90 wt %, specifically 30 to 90 wt %, of the catalyst, but the present invention is not limited to the specific catalyst content in the catalyst layer.

[0094] If necessary, the catalyst layer may further include a carbon material in addition to the catalyst and ionomer described above. The carbon material may include the porous carbon body described above without a catalyst material incorporated therein, a particulate conductive carbon material, a carbon material with a one-dimensional nanostructure (e.g., carbon nanotubes and carbon fibers), a carbon material with a two-dimensional nanostructure (e.g., graphene, reduced graphene oxide, graphene oxide), or a mixture thereof.

[0095] The present invention includes a membrane-electrode assembly comprising the catalyst layer described above.

[0096] A membrane-electrode assembly according to one embodiment of the present invention 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.

[0097] At least one of the first and second catalyst layers may contain the porous carbon material or the catalyst described above. Essentially, at least one of the first and second catalyst layers may be the fuel cell catalyst layer described above.

[0098] If necessary, a microporous layer for improving water repellency may be further provided between the gas diffusion layer and the catalyst layer in the anode or cathode, but the present invention is not limited to the specific structure of the membrane-electrode assembly.

[0099] The gas diffusion layer may be made of any material commonly used in the field of fuel cells, including, but not limited to, polyethylene terephthalate and carbon paper, which have water-repellent properties.

[0100] The electrolyte membrane may be any known membrane commonly used in the field of fuel cells for the purpose of ion conduction. As a practical example, the electrolyte membrane may be a proton-conducting electrolyte membrane. Representative examples of proton-conducting electrolyte membranes include sulfonated block copolymers, perfluorinated polymers having sulfonate groups on the side chains, and sulfonated aromatic polymers. Representative examples of commercial products include Nafion (registered trademark) (manufactured by DuPont), Aciplex (registered trademark) (manufactured by Asahi Kasei Corporation), and Flemion (registered trademark) (manufactured by Asahi Glass Co., Ltd.).

[0101] The present invention includes a fuel cell including the porous carbon body described above, the catalyst described above, the catalyst layer described above, or the membrane electrode assembly described above.

[0102] The present invention includes a fuel cell stack in which a plurality of unit cells, each of which is a membrane electrode assembly as described above, are stacked. In this case, each stacked unit cell may be positioned between separators having a flow channel formed therein.

[0103] The present invention includes a method for producing the porous carbon body described above.

[0104] According to one embodiment, a method for producing a porous carbon body includes the steps of: S1) heat-treating a carbon raw material at 1000°C to 3000°C to remove impurities and crystallizing the carbon raw material; S2) pre-treating the crystallized carbon raw material from which the impurities have been removed in an atmosphere containing at least one heteroelement selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur to introduce activation sites doped with the heteroelement; S3) mixing an additive containing an organic surfactant with the carbon raw material into which the activation sites have been introduced, and then activating the carbon raw material by heat-treating the heteroelement; and S4) activating the activated carbon raw material. S5) subjecting the washed and dried activated carbon raw material to a secondary crystallization treatment; S6) pretreating the carbon raw material that has been subjected to the secondary crystallization treatment in an atmosphere containing at least one second heteroelement selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur to introduce secondary activation sites into the carbon raw material; S7) mixing an additive containing a second organic surfactant with the carbon raw material into which the secondary activation sites have been introduced and heat-treating the mixture to perform a secondary activation treatment; and S8) washing and drying the raw material that has been subjected to the secondary activation treatment.

[0105] Steps S1) to S4) are steps that aim to improve the crystallinity of the carbon raw material while at the same time developing micropores or mesopores of several nanometers or less, thereby creating porosity. Steps S5) to S8) may be steps that further develop coarse pores, including mesopores and macropores, to establish a desired pore structure.

[0106] Specifically, after the carbon raw material is highly crystallized in step S1), a heterogeneous element is inserted into the carbon molecular structure in step S2, forming unstable sites (sites with relatively high energy) in the highly crystalline carbon. During the activation step (step S3), a relatively high frequency of activation reactions is induced at the unstable sites formed in the highly crystallized carbon structure, improving crystallinity and yield. As a result, the unstable sites act as sites for pore formation, producing an intermediate product that simultaneously satisfies both high crystallinity and porosity with well-developed micropores or mesopores of several nanometers or less.

[0107] After this, the intermediate product, which has both high porosity and high crystallinity, is crystallized again, and then unstable sites are formed by inserting foreign elements. This allows the development of mesopores and macropores during the secondary activation process, resulting in the production of a porous carbon material with the desired pore structure and excellent crystallinity.

[0108] Specifically, step S1) is a process of heat-treating the carbon raw material to remove impurities and crystallize it, which allows foreign elements to effectively penetrate into the carbon raw material in step S2). Here, the impurities are substances other than carbon present on the surface or inside of the carbon raw material, and examples of the impurities include petroleum residues and other functional groups, and examples of the impurities include elements other than carbon (boron, carbon, nitrogen, oxygen, phosphorus, sulfur, etc.), but are not limited thereto. In step S1), the lattice constant of the carbon raw material increases, allowing crystallization of part or all of the raw material.

[0109] In one embodiment, the carbon raw material may be amorphous carbon, such as hard carbon (e.g., cellulose, phenolic resin, isotropic pitch), soft carbon (e.g., mesophase pitch, needle coke), or crystalline carbon (e.g., artificial graphite, natural graphite). Specifically, the carbon raw material may be amorphous carbon, more specifically soft carbon. Soft carbon exhibits relatively more anisotropy than hard carbon, with the planes of the carbon layers aligned parallel to each other, and can be crystallized, i.e., graphitized, by heat treatment at 1000°C or higher. In some cases, the carbon raw material may include carbon nanotubes (CNTs), carbon nanofibers (CNFs), or the like.

[0110] Step S1) may be performed at 1000°C to 3000°C for 10 minutes or more under vacuum or in an inert gas (nitrogen, argon, neon, helium, etc.) atmosphere. These conditions are for crystallizing carbon while removing impurities other than carbon present in the carbon raw material. Specifically, step S1) may be performed at 1000°C to 2000°C, more specifically 1000 to 1800°C, for 10 to 100 minutes under vacuum or inert gas atmosphere.

[0111] Step S2) is a process of introducing a predetermined hetero element into the crystallized carbon raw material after impurities have been removed, and during this process, the carbon raw material can be selectively substituted with the hetero element starting from the lower crystalline portion inside. The introduction site of the hetero element can act as a reaction initiation site in the subsequent activation process and also as a site for forming micropores.

[0112] The pretreatment in step S2) may be performed by heat treatment at 500°C to 1000°C for 30 to 100 minutes in an atmosphere containing at least one hetero element selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur, supplied at 100 to 600 sccm. The hetero element may be introduced more selectively into the low-crystallinity portion through pretreatment in which heat treatment is performed for a shorter time at a relatively low temperature in an atmosphere in which a large amount of the hetero element is supplied.

[0113] As a practical example, the heterogeneous element may be at least one selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus and sulfur.

[0114] In step S3), the foreign element inserted in the pretreatment step acts as a reaction initiation point to form fully-fledged micropores, and the reaction between the foreign element and the additive in step S3) can form a microporous structure in which mesopores measuring micrometers to several nanometers in size are mainly developed. As the foreign element doped in the weakly crystalline portion is removed through the activation process, the crystallinity improves and pores are formed, ultimately producing an intermediate product that exhibits high crystallinity while maintaining a highly porous structure.

[0115] The mixture of the carbon raw material having activation sites introduced therein and the additive may contain, based on 100 parts by weight of the carbon raw material having activation sites introduced therein, 0.1 to 10 parts by weight of an inorganic or organic surfactant, 0.1 to 10 parts by weight of an alkali metal hydroxide, and 1 to 10 parts by weight of neutral water. Specifically, the mixture may contain, based on 100 parts by weight of the carbon raw material having activation sites introduced therein, 0.5 to 5 parts by weight of an organic surfactant, 0.5 to 5 parts by weight of an alkali metal hydroxide, and 1 to 8 parts by weight of neutral water.

[0116] The alkali metal hydroxide may be at least one selected from the group consisting of LiOH, NaOH, KOH, RbOH, and CsOH, but is not limited thereto. The organic surfactant may be at least one selected from the group consisting of SDBS, SDS, LDS, CTAB, DTAB, PVP, Triton X-series, Brij-series, Tween-series, poly(acrylic acid), and polyvinyl alcohol, but is not limited thereto.

[0117] The heat treatment in step S3) may be performed in an inert gas atmosphere at 500 to 1000°C for 10 to 100 minutes, more specifically, at 600 to 900°C for 10 to 60 minutes.

[0118] Step S4) is a step of washing and then drying the activated carbon raw material obtained in step S3). Washing can be performed using an acid, a base, water, or the like until the pH of the aqueous dispersion of the carbon raw material reaches 5 to 9, specifically 6 to 8. Drying can be performed at a temperature of 70 to 120°C and atmospheric pressure for 10 to 20 hours, and then at a temperature of 80 to 150°C and vacuum for 1 to 5 hours, but is not limited thereto. Drying in step S4) can be performed under any conditions that can sufficiently remove moisture from the carbon body (intermediate product).

[0119] The secondary crystallization in step S5) can be carried out at 1000°C to 1500°C for 10 to 60 minutes under vacuum or in an inert gas (nitrogen, argon, neon, helium, etc.) atmosphere. Specifically, step S1) can be carried out at 1000°C to 1200°C for 10 to 50 minutes under vacuum or in an inert gas atmosphere.

[0120] The second pretreatment in step S6) may be performed by heat treatment at 500°C to 1000°C for 60 to 500 minutes in an atmosphere containing at least one hetero element selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur supplied at 100 to 600 sccm. When introducing the second hetero element, heat treatment may be performed for a longer time at a relatively low temperature in an atmosphere in which a large amount of hetero element is supplied.

[0121] As a practical example, the heterogeneous element may be at least one selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus and sulfur.

[0122] The secondary activation step (S7) may grow the pores introduced in steps S2) and S3) while simultaneously generating new pores to develop meso- or macropores. The mixture of the carbonaceous material having secondary activation sites introduced therein and the additives in step S6) may contain 0.1 to 10 parts by weight of an inorganic or organic surfactant, 0.1 to 10 parts by weight of an alkali metal hydroxide, and 1 to 10 parts by weight of neutral water, based on 100 parts by weight of the carbonaceous material having secondary activation sites introduced therein. Specifically, the mixture may contain 0.5 to 5 parts by weight of an organic surfactant, 0.5 to 5 parts by weight of an alkali metal hydroxide, and 1 to 8 parts by weight of neutral water, based on 100 parts by weight of the carbonaceous material having secondary activation sites introduced therein. The secondary activation step may involve heat treatment at a relatively high temperature for a longer period of time.

[0123] The alkali metal hydroxide may be at least one selected from the group consisting of LiOH, NaOH, KOH, RbOH, and CsOH, but is not limited thereto. The organic surfactant may be at least one selected from the group consisting of SDBS, SDS, LDS, CTAB, DTAB, PVP, Triton X-series, Brij-series, Tween-series, poly(acrylic acid), and polyvinyl alcohol, but is not limited thereto.

[0124] The heat treatment for secondary activation in step S7) may be performed in an inert gas atmosphere at 500 to 1000°C for 10 to 300 minutes, more specifically, at 650 to 850°C for 30 to 250 minutes.

[0125] The washing and drying in step S8) may be carried out substantially in the same manner as in step S4).

[0126] Example 1 A carbon raw material (Li-435, Denka Company Limited) was heated to 1000°C for 30 minutes under an argon atmosphere for crystallization. Then, a mixed gas of oxygen and nitrogen (50% by volume oxygen and 50% by volume nitrogen in the gas) was supplied to the crystallized carbon raw material at a flow rate of 300 sccm, and the activated site was introduced into the carbon raw material by heat treatment at 600°C for 1 hour. The activated site-introduced carbon raw material was then mixed with an organic surfactant (Triton X-100), potassium hydroxide, and water, with the ratio of 1 part by weight of the activated site-introduced carbon raw material to 100 parts by weight of the activated site-introduced carbon raw material. The mixture was then stirred for 60 minutes and dried with hot air. The resulting mixture was then heat-treated (activated) for 30 minutes at 700°C in a nitrogen atmosphere. Hydrochloric acid, aqueous ammonia, and neutral water were sequentially introduced into the activated sample, each of which was stirred for at least 30 minutes, and then vacuum filtered and washed. During washing, the hydrochloric acid and ammonia water processes were carried out once each, with the hydrochloric acid being added in an amount equal to the weight of the potassium hydroxide previously used, and the ammonia water being added in an amount equal to the weight of the hydrochloric acid previously used. The washing process using neutral water was repeated until the pH of the liquid reached a range of 6 to 8 while stirring. Once the target pH was finally reached, the material was dried at 120°C under atmospheric pressure for more than 12 hours, followed by an additional drying at 120°C under vacuum for more than 1 hour.

[0127] The recovered carbon material after additional drying was heated at 1000°C for 30 minutes under an argon atmosphere for secondary crystallization. Then, a mixed gas of oxygen and nitrogen (50% oxygen by volume, 50% nitrogen by volume) was supplied to the secondary crystallized carbon material at a flow rate of 300 sccm, and the material was heat-treated at 600°C for 1 hour to introduce secondary activation sites. The organic surfactant (Triton X-100), potassium hydroxide, and water were added to the carbon material containing the activated sites (1 part by weight), so that the ratio was 1 part by weight, 1 part by weight, and 3 parts by weight of neutral water per 100 parts by weight of the carbon material containing the activated sites. The mixture was stirred for 60 minutes and then dried with hot air to produce a secondary mixture. The resulting secondary mixture was then heat-treated at 700°C for 60 minutes under a nitrogen atmosphere (secondary activation treatment). The sample subjected to the secondary activation treatment was washed with hydrochloric acid, ammonia water, and neutral water and dried as described above to produce a porous carbon material.

[0128] Examples 2 to 4 A porous carbon body was prepared in the same manner as in Example 1, except that the conditions for introducing the secondary activation site and the conditions for the secondary activation treatment were as shown in Table 1 below.

[0129] [Table 1]

[0130] The produced porous carbon bodies were analyzed under the following conditions.

[0131] Nitrogen adsorption / desorption measurements The nitrogen adsorption / desorption isotherm is obtained by measuring the change in the amount of nitrogen adsorbed onto the porous carbon body in response to changes in nitrogen gas pressure at a temperature of 77K.

[0132] Experimentally, nitrogen adsorption-desorption isotherms were measured according to ASTM D6556.

[0133] Specifically, in addition to ASTM D6556, sample preparation for obtaining nitrogen adsorption / desorption isotherms was as follows: 1) Weigh out 300 mg of a porous carbon sample. 2) Dry the sample in a vacuum of 0.1 Torr or less at 200°C for 12 hours. 3) Nitrogen adsorption / desorption isotherms are measured using a specific surface area measuring device (for example, Micromeritics, ASAP 2460).

[0134] In addition to ASTM D6556, the measurement conditions for obtaining the nitrogen adsorption / desorption isotherm were as follows: Nitrogen adsorption gas, temperature of 77 K using liquid nitrogen, relative pressure (P / P0) measurement accuracy of 0.02, relative pressure (P / P0) range of 0 to 1.

[0135] BJH method for Harkins-Jurassic foundation Using the BJH method, the nitrogen relative pressure (P / P) of the adsorption / desorption isotherm was converted into the pore size (nm) and the nitrogen adsorption amount (cm 3 / g STP) to the pore volume (cm 3 Pore ​​size distributions were obtained by converting relative pressure to pore size (p / g). The Harkins and Jura thickness curve was used to convert relative pressure to pore size. The standard BJH Faas correction was also applied along with the Harkins and Jura thickness curve. Pore size and pore volume were converted from the pore size range of 1.7–300 nm for the adsorption isotherm and from the pore size range of 2.0–50 nm for the desorption isotherm.

[0136] X-ray diffraction measurements The X-ray diffraction pattern of the porous carbon material was obtained according to ASTM D5357 standard using a conventional X-ray diffraction measuring device (e.g., RIGAKU, SmartLab SE) under the following measurement conditions: 0.5 g of porous carbon powder, Cu Kα radiation, scan range 10-70°, scan speed 5.0° / min, scan step size 0.03°.

[0137] d002, La, Lc using X-ray diffraction patterns of porous carbon bodies d002 is the average layer spacing (nm) of the porous carbon body based on the (002) plane, and is calculated using Bragg's law (d 002 =λ / 2sinθ 002 , λ = X-ray wavelength (nm).

[0138] The crystal height (L) determines the crystalline size in porous carbon materials. c , nm) and crystal length (L a , nm) was calculated using the following Scherrer equation: crystalline size(nm)=(k·λ) / (β0·cosθ) L a where k (shape factor) = 1.84, β0 = full width at half maximum (radian) of the (100) peak in the X-ray diffraction pattern of the porous carbon body, λ = X-ray wavelength (nm), and θ = diffraction angle (Bragg angle, radian) at (100). L c where k (shape factor) = 0.9, β0 = full width at half maximum (radian) of the (002) peak in the X-ray diffraction pattern of the porous carbon body, λ = X-ray wavelength (nm), and θ = diffraction angle (Bragg angle, radian) of (002).

[0139] Using the produced porous carbon body, a catalyst, a CCM and a single cell were produced under the following conditions, and their electrochemical properties were analyzed.

[0140] Catalyst production 0.75 g of porous carbon 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, and then 4.95 g of a 20 wt% platinum precursor aqueous solution was added to the dispersion to prepare a mixed solution. The mixed solution was heated at 105°C for 1 hour to load platinum particles onto the porous carbon. The mixed solution was then cooled to room temperature, and the porous carbon loaded with platinum particles was filtered, thoroughly washed with distilled water, and dried in a vacuum dryer at 250°C to prepare a catalyst.

[0141] Catalyst Coated Membrane (CCM) Fabrication Membrane electrode assemblies (MEAs) have an active area of ​​25 cm 2 A catalyst-coated membrane (CCM) was prepared using the catalyst. In all tests, a commercial Pt / C (manufacturer: TANAKA, product number 1021-E941, Pt catalyst loading: 19.9%) was used as the oxidation electrode (anode) catalyst, and the catalyst prepared in the examples was used as the active reduction electrode (cathode) catalyst. 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 slurries were coated onto a fluorinated polyimide (FPI) film using a bar coater at a constant speed of 15 mm / sec. This film was dried at 60 °C for 12 hours to prepare a reduction electrode. The reduction electrode thus prepared was then pressed together with the commercial oxidation electrode and Nafion membrane using a vacuum press at 145 °C for 15 minutes to prepare a CCM.

[0142] Performance Test PEMFC performance was tested at 80°C. For the high-humidification test, the oxidation electrode was supplied with fully humidified (100% relative humidity) high-purity hydrogen, and the reduction electrode was supplied with fully humidified (100% relative humidity) air. For the low-humidification test, the oxidation electrode was supplied with low-humidified (40% relative humidity) high-purity hydrogen, and the reduction electrode was supplied with low-humidified (40% relative humidity) air. For both the high-humidification and low-humidification tests, 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 H / Air = 1.5 / 1.8, and the back pressure was maintained at 1.5 bar.

[0143] Electrochemical impedance spectroscopy (EIS) was performed at 0.1 V RHEMeasurements were performed in the range of 0.1 to 100 kHz under low-humidified (40% relative humidity) high-purity hydrogen at 500 sccm and low-humidified (40% relative humidity) high-purity nitrogen at 500 sccm under low-voltage conditions. The back pressure was maintained at 1.5 bar during the test.

[0144] For comparison with the porous carbon bodies produced in the Examples, the crystallinity and pore characteristics of the commercial carbon bodies were analyzed in the same manner as in the analysis of the porous carbon bodies. Furthermore, catalysts, CCMs, and single cells were produced using the commercial carbon bodies in the same manner as the porous carbon bodies, and their electrochemical properties were evaluated. The commercial carbon bodies used for comparison were Li-250 (Denka Company Limited), Li-400 (Denka Company Limited), Li-435 (Denka Company Limited), and MH-00 (CNovel TM , TOYO TANSO), MH-18(CNovel TM , TOYO TANSO) and MH-18_2μm (CNovel TM , TOYO TANSO).

[0145] Hereinafter, when referring to the results measured using each commercial carbon material or the porous carbon material prepared in the examples, the specific trade name of the commercial carbon material or the number of the example is simply used. TM The electrochemical characteristics of a cell fabricated using MH-18 (CNovel, TOYO TANSO) as a Pt support can be referred to as the electrochemical characteristics of MH-18. TM A delta graph derived from the nitrogen adsorption / desorption isotherm of the porous carbon body (Toyo Tanso) may be referred to as the delta graph of MH-18. As an example, the porous carbon body prepared in Example 1, the catalyst prepared using the porous carbon body as a Pt support, the CCM, the unit cell, and the electrochemical characteristics of the unit cell may be referred to as the porous carbon body of Example 1, the catalyst of Example 1, the CCM of Example 1, the unit cell of Example 1, and the electrochemical characteristics of Example 1.

[0146] The specific surface area (SSA) of the porous carbon bodies prepared in the examples and the comparative samples was 2 to 5 nm. 2 / g), 2~100nm specific surface area (SSA2, m 2 / g), d 002 (nm), L a The thickness (nm) and average number of graphite layers (average number of layers, pieces) were measured and summarized in Table 2.

[0147] [Table 2]

[0148] Figure 1 is a diagram showing the delta graph of the porous carbon body of Example 1. Delta graphs of comparative samples are also shown in Figure 2 (delta graph of Li-400 sample) and Figure 3 (delta graph of MH-18 sample).

[0149] The porous carbon bodies prepared in the examples exhibited hysteresis in the nitrogen adsorption / desorption curves, and as shown in FIG. 1, the hysteresis closed at a relative pressure of approximately 0.4.

[0150] The porous carbon bodies prepared in the examples had two maxima on the delta graph as shown in FIG. 1, and the magnitude of the maximum point located at a relatively high relative pressure (the second maximum point) was larger than the magnitude of the maximum point located at a relatively low relative pressure (the first maximum point).

[0151] The number of maximum points and the value of the first maximum point (cm) on the delta graph of the porous carbon body produced in the example and the comparative sample are shown. 3 / g STD), the value of the second maximum point (cm 3 / g STD) and the ratio of the values ​​at the maximum points (value at the first maximum point / value at the second maximum point) are summarized in Table 3.

[0152] [Table 3]

[0153] Table 4 shows the positions of the first maximum point (P / P), the second maximum point (P / P), and the size of the minimum point between the first maximum point and the second maximum point (expressed as a relative percentage of the value of the first maximum point, with the value of the first maximum point as the reference) on the delta graphs of the porous carbon bodies prepared in the Examples and the comparative samples.

[0154] [Table 4]

[0155] In the nitrogen adsorption / desorption isotherms of the porous carbon bodies produced in the examples and the comparative samples, the hysteresis area (HA1) located in the relative pressure range of 0.4 to 0.9 and the hysteresis area (HA2) located in the relative pressure range of 0.9 to 1.0 were determined, and the area ratio (HA2 / HA1) was calculated and summarized in Table 5.

[0156] [Table 5]

[0157] The electrochemical characteristics of the cells fabricated using the porous carbon bodies of the examples and the comparative carbon bodies are summarized in Table 6 (low humidity condition of 40% relative humidity) and Table 7 (high humidity condition of 100% relative humidity). In Tables 6 and 7, J@0.6V means the current density measured at a fixed voltage of 0.6V, and V@0.8A / cm 2 and V@1.5A / cm 2 is 0.8A / cm 2 and 1.5A / cm 2 In Tables 6 and 7, "Vratio" means the voltage measured at a fixed current density of 0.8 A / cm 2 The voltage measured under the low current density condition of 1.5A / cm 2 This is the ratio (unit: %) of the voltage measured under high current density conditions.

[0158] [Table 6]

[0159] [Table 7]

[0160] As a result of electrochemical impedance spectroscopy under low humidity conditions, the resistance of the reduction electrodes manufactured using the carbon bodies of Examples 1 to 4 was 0.10 Ω / cm 2 and the Li-250 reduction electrode and Li-400 reduction electrode are 0.15 Ω / cm 2 , Li-435 reduction electrode is 0.13Ω / cm 2 , MH-00 reduction electrode and MH-18 reduction electrode are both 0.12 Ω / cm 2 , MH-18_2μm reduction electrode is 0.11Ω / cm 2 It was.

[0161] The above embodiment is merely an example, and the present invention is not limited thereto. Anything that has substantially the same configuration as the technical idea described in the claims of the present invention and achieves the same effects is included in the technical scope of the present invention.

Claims

1. A porous carbon body having the following properties: Physical property 1: Nitrogen desorption isotherm (N ２ The surface area of ​​the pores with a size of 2 nm to 5 nm obtained by desorption isotherm is 100 m ２ / g to 500m ２ / g, Physical property 2: Nitrogen desorption isotherm (N ２ The surface area of ​​the pores with a size of 2 nm to 100 nm obtained by desorption isotherm is 200 m ２ / g~1500m ２ / g, Property 3: Nitrogen adsorption / desorption isotherm (N ２ The delta graph, which is a graph of the value obtained by subtracting the value of the nitrogen adsorption isotherm from the value of the nitrogen desorption isotherm as a function of relative pressure in the relative pressure range of 0.3 to 1.0, has at least a first maximum point and a second maximum point, and the value of the first maximum point located at a lower relative pressure is smaller than the value of the second maximum point located at a higher relative pressure.

2. 2. The porous carbon body according to claim 1, wherein a ratio of the first maximum value divided by the second maximum value is 0.10 to 0.

95.

3. The first maximum point is the relative pressure (P / P ０ ) is located in the range of 0.4 or more to less than 0.9, and the second maximum point is located in the range of the relative pressure (P / P ０ 2. The porous carbon body according to claim 1, wherein the ρ is in the range of 0.9 or more and less than 1.

0.

4. The first maximum point is the relative pressure (P / P ０ ) 0.45 to 0.80, and the second maximum point is located in the range of relative pressure (P / P ０ 4. The porous carbon body according to claim 3, wherein the σ is in the range of 0.93 to 0.

98.

5. In the nitrogen adsorption / desorption isotherm, the relative pressure (P / P ０ ) hysteresis area in the range of 0.9 to 1.0 relative pressure (P / P ０ 2. The porous carbon body according to claim 1, wherein the area ratio of the hysteresis area in the region of 0.4 to 0.9 is 0.1 to 2.

0.

6. The porous carbon body according to claim 5, wherein the area ratio is 0.1 to 1.

5.

7. The porous carbon body according to any one of claims 1 to 6, further satisfying the following property 4: Physical property 4: Average layer spacing (d ００２ ) is 0.335 nm to 0.350 nm.

8. The porous carbon body according to any one of claims 1 to 6, further satisfying the following physical property 5: Physical property 5: Lattice constant in the a-axis direction measured by X-ray diffraction method (L ａ ) is 4nm to 12nm.

9. 7. The porous carbon body according to claim 1, wherein the relative pressure (P / P0) at the point where the hysteresis loop closes is 0.45 or less.

10. 7. The porous carbon body according to claim 1, wherein in the delta graph, a value of a minimum point located between the first maximum point and the second maximum point is 15 to 90% of the value of the first maximum point.

11. The porous carbon body according to claim 1 , wherein the porous carbon body is doped with a different element.

12. A catalyst for a fuel cell, comprising a catalytic material supported on the porous carbon body according to claim 1 .

13. A catalyst layer for a fuel cell, comprising the catalyst according to claim 12 and an ionomer.

14. A polymer electrolyte membrane fuel cell comprising the catalyst of claim 12.

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