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 the surface area properties of pores having a size of 2 nm or more and 5 nm or less, the surface area properties of pores having a size of 2 nm or more and 100 nm or less, and the physical properties shown in a superimposed graph obtained by superimposing a first pore volume distribution graph obtained by a nitrogen adsorption isotherm and a second pore volume distribution graph obtained by a nitrogen desorption isotherm.

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 / Pioneering 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 catalyst durability 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: Based on the BJH method based on the Harkins-Jura equation, the first pore volume distribution graph obtained from the nitrogen adsorption isotherm and the second pore volume distribution graph obtained from the nitrogen desorption isotherm are superimposed on one another. The superimposed graph has three intersections, P1, P2, and P3, in the order of increasing pore diameter in the pore diameter range of 2 to 50 nm.

[0012] In one embodiment, the P3 may be located in a pore diameter range of more than 10 nm to 40 nm.

[0013] In one embodiment, the P2 may be located in a pore diameter range of 5 nm to 25 nm.

[0014] In one specific example, in the superimposed graph, the area ratio obtained by dividing the area of ​​the closed curve from P2 to P3 by the area of ​​the closed curve from P1 to P2 may be 2.5 or less.

[0015] The porous carbon body according to one embodiment may further satisfy the following property 4. Physical property 4: Based on the BJH method based on the Harkins-Jura equation, the value obtained by subtracting the cumulative volume distribution of the second pores from the cumulative volume distribution of the first pores obtained by the nitrogen adsorption isotherm and the cumulative volume distribution of the first pores obtained by the nitrogen desorption isotherm, depending on the pore diameter, is a positive value in the pore diameter range of 2 to 30 nm.

[0016] In one specific example, a cumulative delta graph, which is a graph of the value obtained by subtracting the second pore cumulative volume distribution value from the first pore cumulative volume distribution value according to the pore diameter, may include a first decrease region, a first increase region, a second decrease region, and a second increase region in the direction in which the pore diameter increases.

[0017] In one embodiment, the boundary between the first increasing region and the second decreasing region may be located in a pore diameter range of 5 nm to 20 nm.

[0018] In one embodiment, the boundary between the second decreasing region and the second increasing region may be located in a pore diameter range of 10 nm to 30 nm.

[0019] In one embodiment, the positive value is 0.05 cm 3 / g or more.

[0020] The porous carbon body according to one embodiment may further satisfy the following property 5. Physical property 5: The average layer spacing (d002) measured by X-ray diffraction is 0.335 nm to 0.350 nm.

[0021] The porous carbon body according to one embodiment may further satisfy the following property 6. Physical Property 6: Lattice constant in the a-axis direction (L a ) is 4nm to 10nm.

[0022] In one embodiment, the porous carbon body may be a porous carbon body doped with a different element.

[0023] 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.

[0024] A catalyst layer for a fuel cell according to one disclosure contains the above-described catalyst and an ionomer.

[0025] The present invention includes a polymer electrolyte membrane fuel cell comprising the catalyst described above. [Effects of the Invention]

[0026] The porous carbon body according to one embodiment of the present invention has a pore structure including an appropriate amount of bottleneck-shaped pores, and therefore can exhibit improved catalyst durability when used as a catalyst support for a fuel cell.

[0027] The porous carbon body according to one embodiment has a pore structure including an appropriate amount of bottleneck-shaped pores having a wide size range, and can exhibit improved catalytic activity and durability when used as a catalyst support for fuel cells.

[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 graph showing an overlay of a porous carbon body manufactured according to an embodiment; [Figure 2] 10 is a diagram showing an overlaid graph of a comparative sample. [Figure 3] 10 is a diagram showing an overlaid graph of a comparative sample. [Figure 4] 1 is a diagram showing a cumulative delta graph of a porous carbon body manufactured according to an embodiment; [Figure 5]1 is a diagram showing a cumulative delta graph of a comparative sample. [Figure 6] 1 is a diagram showing a cumulative 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 durability and catalytic 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 be in a trade-off relationship. During this research, the inventors discovered that bottleneck-shaped pores in porous carbon materials for use as catalyst supports in fuel cells, unlike conventionally known pores, are advantageous for improving the durability and catalytic activity of fuel cell catalyst materials. Based on this discovery, the inventors furthered their research and established a pore structure that can improve the durability and activity of catalyst materials while preventing the adverse effects that can be caused by bottleneck-shaped pores, thereby completing the present invention.

[0038] A porous carbon body according to one disclosure satisfies the following property 1, property 2, and property 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: Based on the BJH method based on the Harkins-Jura equation, the first pore volume distribution graph obtained from the nitrogen adsorption isotherm and the second pore volume distribution graph obtained from the nitrogen desorption isotherm are superimposed on one another. The superimposed graph has three intersections, P1, P2, and P3, in the direction of increasing pore diameter in the pore diameter range of 2 to 50 nm.

[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 100m2 / 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 220m 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: Based on the BJH method based on the Harkins-Jura equation, the first pore volume distribution graph obtained from the nitrogen adsorption isotherm and the second pore volume distribution graph obtained from the nitrogen desorption isotherm are superimposed on one another. The superimposed graph has three intersections, P1, P2, and P3, in the direction of increasing pore diameter in the pore diameter range of 2 to 50 nm.

[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). 3 / g STP value. The BJH method based on the Harkins-Jura equation was used to calculate the nitrogen relative pressure (P / P0) of the adsorption / desorption isotherm as a function of the pore diameter (nm) and the nitrogen adsorption amount (cm 3 / g STP) to the pore volume (cm 3 / g), a pore volume distribution graph is obtained. The pore volume distribution graph is a graph of pore volume by pore diameter (size), and specifically, the x-axis is the logarithmic scale of pore diameter (nm) and the x-axis is the pore volume (cm 3 The first pore volume distribution graph may be a semi-logarithmic pore volume distribution graph obtained by the BJH method based on the Harkins-Jura equation from a nitrogen adsorption isotherm obtained by nitrogen adsorption, and the second pore volume distribution graph may be a semi-logarithmic pore volume distribution graph obtained by the BJH method based on the Harkins-Jura equation from a nitrogen desorption isotherm obtained by nitrogen desorption. The superimposed graphs have the same logarithmic x-axis (nm) and the same y-axis (cm 3 / g) may refer to a semi-log scale graph in which the first pore volume distribution graph and the second pore volume distribution graph are shown together.

[0047] Property 3 can be satisfied when a porous carbon material contains a considerable number of bottleneck-shaped pores (hereinafter referred to as bottleneck pores) and also contains bottleneck pores with a wide range of sizes. Only when a porous carbon material satisfies property 3 can it obtain the intended benefits of bottleneck pores while suppressing the adverse effects of the bottleneck shape.

[0048] Specifically, if the graph has no intersections or one or two intersections in the pore diameter range of 2 to 50 nm, the degree of bottleneck pore development is minimal, making it difficult to achieve significant results when used as a catalyst support. On the other hand, if the graph has four or more intersections in the pore diameter range of 2 to 50 nm, mesopores including bottleneck pores develop excessively, making it difficult to transport materials, including gas phases, within the carbon body, and flooding occurs easily, making it difficult to prevent the adverse effects caused by bottleneck-shaped pores.

[0049] The positions of P2 and P3 in the superposition graph are indices related to the size of the bottleneck pore. Specifically, P3 in the superposition graph is an index mainly related to the size of the internal pore region in the bottleneck pore, and P2 is an index mainly related to the size of the bottleneck region in the bottleneck pore. Furthermore, the positions of P3 and P2 are indices indicating the degree of bottleneck morphology, i.e., the degree to which the bottleneck is close to a closed pore.

[0050] In one embodiment of the porous carbon material, P3 on the superposition graph may be located in a pore diameter range of more than 10 nm to less than 40 nm, specifically 11 nm to 35 nm. By positioning P3 between 10 nm to less than 40 nm, specifically 11 nm to 35 nm, the catalytic material can be evenly loaded within the bottleneck pores while providing sufficient space for the catalytic material to prevent aggregation within the pores. Furthermore, gaseous oxygen, a reactant, and water, a product, can be smoothly transported and discharged through the available space. Additionally or independently, P2 on the superposition graph may be located in a pore diameter range of 5 nm to 25 nm, specifically 5 nm to 20 nm. By positioning P2 between 5 nm to 25 nm, specifically 5 nm to 20 nm, the catalytic material can be effectively prevented from coming into direct contact with an ion transport medium (e.g., an ionomer) that penetrates through the meso- or macropores of the porous carbon material and is bound to the porous carbon material. In addition, the phenomenon in which the catalyst material is not released to the outside of the pores during the operation of the fuel cell can be effectively prevented.

[0051] In one specific example, the difference between the position of P3 and the position of P2 (P3 position - P2 position) can be 5 nm to 20 nm, specifically 5 nm to 15 nm. When the bottleneck pore has the above-mentioned difference between P3 and P2, direct contact between the ion transport mediator and the catalytic material can be prevented without impeding the transport and discharge of the reactants and products, oxygen and water, due to a bottleneck shape.

[0052] In one specific example, in the region of x-axis reference 2 nm-P1, a first pore volume distribution graph based on a nitrogen adsorption isotherm may be positioned higher (at a larger y value) than a second pore volume distribution graph based on a nitrogen desorption isotherm. In the region of x-axis reference P1-P2, a second pore volume distribution graph based on a nitrogen desorption isotherm may be positioned higher than a first pore volume distribution graph based on a nitrogen adsorption isotherm. In the region of x-axis reference P2-P3, a first pore volume distribution graph based on a nitrogen adsorption isotherm may be positioned higher than a second pore volume distribution graph based on a nitrogen desorption isotherm. In the region of x-axis reference P3-50 nm, a second pore volume distribution graph based on a nitrogen desorption isotherm may be positioned higher than a first pore volume distribution graph based on a nitrogen adsorption isotherm.

[0053] In other words, the three intersections of P1, P2, and P3 correspond to the boundary points between two regions in the direction of increasing pore diameter: a region where the pore volume is larger during desorption than during adsorption (P1-P2 region), and a region where the pore volume is larger during adsorption than during desorption (P2-P3 region).

[0054] Due to these three intersections P1, P2, and P3, the superimposed graph can have a first closed curve formed by the second pore volume distribution graph located at the top and the first pore volume distribution graph located at the bottom on the x-axis reference P1-P2, and a second closed curve formed by the first pore volume distribution graph located at the top and the second pore volume distribution graph located at the bottom on the x-axis reference P2-P3.

[0055] In the superimposed graph, the area ratio of the area of ​​the closed curve from P2 to P3 (second closed curve) divided by the area of ​​the closed curve from P1 to P2 (first closed curve) can be 2.50 or less. Specifically, the area of ​​the second closed curve (A cl2 ) to the area of ​​the first closed curve (A cl1 ) divided by the area ratio (A cl2 / A cl1 ) can be 0.01 to 2.50, specifically 0.01 to 2.40, more specifically 0.10 to 2.30, and even more specifically 0.40 to 2.30. cl2 / A cl1 ) is satisfied, when the porous carbon body is used as a support for supporting a catalytic substance, the catalyst can have an improved electrochemical specific surface area (ESCA) and also have significantly improved durability. cl2 / A cl1 The area ratio may be a physical property related to the size distribution of the bottleneck region of the bottleneck pores contained in the pore structure of the porous carbon body and the size distribution of the internal pore region. The above area ratio may indicate that the pores having a bottleneck shape (bottleneck pores) are formed of bottleneck pores and internal pores having a fairly wide size distribution.

[0056] The porous carbon body according to one embodiment may further satisfy the following property 4.

[0057] Physical property 4: Based on the BJH method based on the Harkins-Jura equation, in the first pore cumulative volume distribution obtained by nitrogen adsorption isotherm and the second pore cumulative volume distribution obtained by nitrogen desorption isotherm, the value obtained by subtracting the second pore cumulative volume distribution value from the first pore cumulative volume value according to pore diameter is positive in the pore diameter range of 2 to 30 nm.

[0058] The cumulative pore volume distribution was calculated by the BJH method based on the Harkins-Jura equation, where the nitrogen relative pressure (P / P0) of the nitrogen adsorption / desorption isotherm was converted to the pore diameter (nm) and the cumulative nitrogen adsorption amount (cm) up to each pore diameter.3 / g STP) was calculated by dividing the cumulative pore volume (cm 3 / g). In other words, the cumulative pore volume distribution can be obtained by accumulating the pore volume up to each pore diameter based on the above-mentioned pore volume distribution graph. Therefore, the cumulative pore volume distribution is also calculated by dividing the x-axis of the pore diameter (nm) in a logarithmic scale by the x-axis of the cumulative pore volume (cm). 3 The graph may be a semi-logarithmic scale graph having a y-axis of (μm / g). The first cumulative pore volume distribution may be calculated from a pore volume distribution graph obtained by a nitrogen adsorption isotherm, and the second cumulative pore volume distribution may be calculated from a pore volume distribution graph obtained by a nitrogen desorption isotherm.

[0059] The cumulative pore volume distribution during nitrogen adsorption and the cumulative pore volume distribution during nitrogen desorption may be more sensitive to and influenced by the size distribution of the bottleneck pores that form the bottleneck pore group than the pore volume distribution graph.

[0060] In detail, the value obtained by subtracting the cumulative volume distribution value of the second pores from the cumulative volume distribution value of the first pores (hereinafter referred to as the cumulative volume difference) can more directly reflect the size distribution of the bottleneck pores that form the bottleneck pore group.

[0061] When the pore structure of a porous carbon body contains a significant amount of bottleneck pores and also contains bottleneck pores and internal pores of various sizes, the cumulative volume difference can exhibit a positive value over the entire pore diameter range of 2 to 30 nm. Specifically, the cumulative volume difference over the entire pore diameter range of 2 to 30 nm can be greater than 0.05 cm. 3 / g or more, more specifically 0.05 to 2.0 cm 3 / g, and more specifically, 0.05 to 1.8 cm 3 Bottleneck pores of various sizes are very advantageous in simultaneously improving catalytic activity, as represented by electrochemical specific surface area (ESCA) and mass activity, and catalyst durability, as represented by the reduction rate of ESCA and the reduction rate of mass activity.

[0062] As mentioned above, the cumulative volume difference according to pore diameter can more directly reflect the size distribution of the bottleneck pores that form the bottleneck pore group. In particular, a graph of the value of the cumulative volume difference according to pore diameter can be defined as a cumulative delta graph. As the value of the cumulative volume difference according to pore diameter, the cumulative delta graph has an x-axis of log-scale pore diameter (nm) and an x-axis of cumulative volume difference (cm 3 The graph may be a semi-logarithmic scale graph with a y-axis of (μm / g). In this case, the cumulative delta graph may have a pore diameter range of 2 to 30 nm.

[0063] In one embodiment, the cumulative delta graph may include a first decrease region, a first increase region, a second decrease region, and a second increase region sequentially or continuously in the direction of increasing pore diameter.

[0064] In the cumulative delta graph, the decreasing region is the region where the cumulative volume difference value decreases as the pore diameter increases, and the increasing region is the region where the cumulative volume difference value increases as the pore diameter increases.

[0065] Specifically, the cumulative delta graph may include, in the pore diameter range of 2 to 30 nm, a first decreasing region including a pore diameter of 2 nm, a first increasing region, a second decreasing region, and a second increasing region including a pore diameter of 30 nm, in the direction of increasing pore diameter. Thus, the cumulative delta graph may have a maximum point corresponding to the boundary point between the first increasing region and the second decreasing region, or may have a single maximum point.

[0066] The boundary (boundary point) between the first increasing region and the second decreasing region may be located in a pore diameter range of 5 nm to 20 nm, and simultaneously or independently, the boundary between the second decreasing region and the second increasing region may be located in a pore diameter range of 10 nm to 30 nm.

[0067] The shape of the single maximum point in the cumulative delta graph may indicate that the porous carbon body contains bottleneck pores of various sizes, and that the bottleneck pores are uniformly and well-developed across a very wide range of pore sizes, resulting in a pore structure with well-connected bottleneck pores present across a very wide range of pore sizes. It may also indicate the location of the boundary between the first increasing region and the second decreasing region, the location of the boundary between the second decreasing region and the second increasing region, and the size of the bottleneck pores and internal pores in such a bottleneck structure.

[0068] The porous carbon material has a pore structure including bottleneck pores that are uniformly and well-developed across a wide range of pore sizes and well-connected to each other, which prevents aggregation, leaching, and poisoning by ionomers, etc. of the catalytic material, and allows for fine and uniform loading, thereby further improving both catalytic activity and catalyst durability. Furthermore, the porous carbon material has a pore structure including bottleneck pores that are uniformly and well-developed across a wide range of pore sizes and well-connected to each other, which allows for smooth and rapid supply of a gas phase to the particulate catalytic material and smooth and rapid discharge of a liquid phase resulting from the fuel cell reaction, thereby effectively preventing flooding. Examples of gas phases include gases involved in the electrochemical reaction of a fuel cell, such as oxygen, air, and hydrogen, and examples of liquid phases include liquids containing the reaction products of the electrochemical reaction of a fuel cell, such as water, but the present invention is not limited by the specific gas and liquid phases.

[0069] The porous carbon body according to one embodiment may further satisfy the following property 5.

[0070] Physical Property 5: Average layer spacing (d 002 ) is 0.335nm~0.350nm The average layer spacing (d 002 ) is an index that directly indicates the crystallinity of the carbon that forms the porous carbon body. 002It can mean that the pore structure of the porous carbon material including the bottleneck pores is formed by a carbon skeleton having excellent crystallinity.

[0071] 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.

[0072] In addition to or independently of this, one specific porous carbon material may further satisfy the following property 6.

[0073] Physical Property 6: Lattice constant in the a-axis direction (L a ) is 4 nm to 10 nm, specifically 6 nm to 10 nm, more specifically 7 nm to 10 nm, and even more specifically 7.5 nm to 10 nm Property 6 is also related 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 that satisfies property 6 is advantageous because it reduces the number of defect sites that are vulnerable to oxidation.

[0074] In addition to or independently of this, the porous carbon body may further satisfy the following property 7.

[0075] Physical Property 7: The average number of graphene layers calculated by X-ray diffraction is 6 to 20, specifically 7 to 15, more specifically 8 to 15 Property 7 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.

[0076] In an advantageous example, the porous carbon body may have the above-described pore structure and excellent crystallinity satisfying all of properties 5, 6, and 7. When the porous carbon body has the above-described pore structure and at the same time has crystallinity satisfying all of properties 5, 6, and 7, 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%.

[0077] Furthermore, when a porous carbon body has the above-described pore structure and at the same time has crystallinity that satisfies all of properties 5, 6, and 7, 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.

[0078] In one embodiment, the porous carbon material may be an aggregate of primary particles randomly aggregated together, and the primary particles may include hollow particles. Therefore, the pore structure of the porous carbon material may be formed by 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. The average primary particle diameter of the porous carbon material may be 10 nm to 30 nm. The average primary particle diameter may be measured according to ASTM D3849.

[0079] 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.

[0080] The present invention includes a fuel cell catalyst comprising the porous carbon body described above.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] The present invention includes a catalyst layer for a fuel cell that contains the porous carbon body described above.

[0086] 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.

[0087] The present invention includes a catalyst layer for a fuel cell containing the above-described catalyst.

[0088] A catalyst layer for a fuel cell according to one disclosure can include the above-described catalyst and an ionomer.

[0089] 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.).

[0090] 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.

[0091] 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.

[0092] The present invention includes a membrane-electrode assembly comprising the catalyst layer described above.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.).

[0098] 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.

[0099] 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.

[0100] The present invention includes a method for producing the porous carbon body described above.

[0101] According to one embodiment, a method for manufacturing a porous carbon body may include: S1) heat-treating a carbon raw material at 1000°C to 3000°C to remove impurities and crystallize the carbon raw material; S2) pre-treating the crystallized carbon raw material from which the impurities have been removed at a temperature of 500°C to 1000°C for 200 to 500 minutes in an atmosphere containing at least one foreign element selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur to introduce activation sites, which are sites doped with the foreign element; S3) mixing an additive including 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 at 500°C to 1000°C for 200 to 400 minutes to remove the foreign element; S4) washing and drying the activated carbon raw material; and S5) heat-treating the washed and dried activated carbon raw material in an inert atmosphere at 1200°C to 1700°C to close the pores.

[0102] Steps S1) to S4) are processes mainly aimed at improving the crystallinity of the carbon raw material and at the same time forming a large number of meso- and macropores, and step S5) may be a process of closing the openings of the pores formed in steps S1) to S4) to convert the pore shape into bottleneck-shaped pores.

[0103] Specifically, after highly crystallizing the carbon raw material in step S1), a large amount of heterogeneous elements is inserted into the carbon molecular structure in step S2, forming a high density of 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 crystalline carbon structure, improving crystallinity and yield. As a result, the unstable sites act as pore-forming sites, producing a carbon body that simultaneously satisfies both high porosity with well-developed mesopores and macropores and high crystallinity. Subsequently, high-temperature heat treatment in step S5 converts the pores formed in the carbon body into a bottleneck shape, producing a porous carbon body having a pore structure with well-developed bottleneck pores over a wide range of sizes.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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 pore formation.

[0108] The pretreatment in step S2) may be performed by heat treatment at a temperature of 500°C to 1000°C for 200 to 500 minutes, specifically at 500°C to 800°C for 250 to 400 minutes, in an atmosphere containing at least one foreign element selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur, supplied at 100 to 600 sccm. A large amount of foreign element can be introduced into the carbon body through pretreatment in which heat treatment is performed for a longer period of time at a relatively low temperature in an atmosphere in which a large amount of foreign element is supplied.

[0109] 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.

[0110] In step S3), the foreign element inserted in the pretreatment step acts as a reaction initiation point to form pores, 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. Also, as the foreign element doped in the weakly crystalline portion is removed through the activation process, the crystallinity improves and pores are formed, so that a carbon body that exhibits high crystallinity while having a highly porous structure can be produced.

[0111] 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.

[0112] 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.

[0113] The heat treatment in step S3) may be performed in an inert gas atmosphere at 500 to 1000°C for 200 to 400 minutes, specifically at 600 to 900°C for 250 to 400 minutes.

[0114] 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).

[0115] The pore-closing treatment in step S5) may be performed at 1200 to 1700°C for 10 to 1500 minutes under vacuum or in an inert gas (nitrogen, argon, neon, helium, etc.) atmosphere. Specifically, step S5) may be performed at 1200 to 1600°C for 10 to 1200 minutes under vacuum or in an inert gas atmosphere. During the pore-closing treatment in step S5), the heating rate may be on the order of 1°C / min to 10°C / min, and cooling after the pore-closing treatment may be air-cooling.

[0116] Example 1 A carbon raw material (Li-435, Denka Company Limited) was crystallized by heating at 1000°C for 30 minutes under an argon atmosphere. Then, a mixed gas of oxygen and nitrogen (50% by volume oxygen and 50% by volume nitrogen) was supplied to the crystallized carbon raw material at a flow rate of 300 sccm, and the activated site was introduced by heat treatment at 600°C for 5 hours. Next, an organic surfactant (Triton X-100), potassium hydroxide, and water were added to the activated site-introduced carbon raw material so that the ratio was 1 part by weight of organic surfactant, 1 part by weight of potassium hydroxide, and 3 parts by weight of neutral water per 100 parts by weight of the activated site-introduced carbon raw material. The mixture was then stirred for 300 minutes and dried with hot air. The resulting mixture was then heat-treated (activated) at 700°C for 300 minutes under a nitrogen atmosphere. Hydrochloric acid, aqueous ammonia, and neutral water were sequentially added to the activated sample, each stirred for 30 minutes or more, 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 used previously, and the ammonia water being added in an amount equal to the weight of the hydrochloric acid used previously. The washing process using neutral water was repeated until the pH of the solution reached a range of 6-8 while stirring. Once the target pH was finally reached, the mixture was dried at 120°C under atmospheric pressure for at least 12 hours, followed by additional drying at 120°C under vacuum for at least 1 hour. The carbon material recovered after additional drying was then heat-treated in a nitrogen atmosphere at 1600°C for 450 minutes (pore-closing treatment, heating rate = 5°C / min, air-cooling) to produce a porous carbon material.

[0117] Examples 2 to 4 A porous carbon body was produced in the same manner as in Example 1, except that the pore-closing treatment was carried out under the conditions shown in Table 1.

[0118] [Table 1]

[0119] The produced porous carbon bodies were analyzed under the following conditions.

[0120] 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.

[0121] Experimentally, nitrogen adsorption-desorption isotherms were measured according to ASTM D6556.

[0122] 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).

[0123] 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.

[0124] 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.

[0125] 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°.

[0126] d002, La, Lc using X-ray diffraction patterns of porous carbon bodies d 002 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).

[0127] 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).

[0128] Using the prepared porous carbon body, a catalyst and a half cell were prepared according to the following conditions, and their electrochemical properties were analyzed.

[0129] 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.

[0130] Half-cell evaluation Electrochemical measurements were carried out at room temperature using a 0.1 M HClO4 aqueous electrolyte, a Ag / AgCl (saturated KCl, 3 M) reference electrode, a platinum wire counter electrode, and a rotating disk electrode (RDE) connected to an electrochemical analyzer (ALS Japan; serial number MD2503) as the working electrode. All potentials were measured relative to the reversible hydrogen electrode (RHE), and therefore the potential of the Ag / AgCl reference electrode was measured relative to the RHE (V RHE (Correction method: After purging high-purity hydrogen gas into a 0.1M HClO4 aqueous solution electrolyte for 30 minutes, the working electrode and counter electrode were all connected with platinum wire, and the OCV (open circuit voltage) was measured with respect to an Ag / AgCl reference electrode. Corrections were made to the RHE reference potential using the OCV values ​​measured during all half-cell evaluations.)

[0131] The catalyst was added to distilled water, Nafion (5 wt%), and isopropyl alcohol (IPA), and ultrasonically dispersed to prepare a catalyst ink. The mass ratio of catalyst to Nafion in the catalyst ink was 10:3. The catalyst ink was applied to a glassy carbon RDE electrode (5 mm) using a micropipette at a concentration of 100 μg / cm on a platinum basis. 2 The working electrode was prepared by loading the electrode with HClO4 at 0.05 to 1.05 V and then drying at room temperature. RHEThe catalyst was electrochemically activated at a voltage scan rate of 100 mV / s over the voltage range.

[0132] Cyclic voltammetry (CV) measurements were performed at 0.05 to 1.05 V after purging with high-purity nitrogen gas for 30 minutes. RHE The voltage range was scanned at a voltage scanning rate of 20 mV / s.

[0133] Electrochemically active surface (ECSA) is 0.05 to 0.4 V RHE The hydrogen desorption area was calculated using the

[0134] The oxygen reduction reaction (ORR) measurement was performed after purging with high-purity oxygen gas for 30 minutes. RHE The measurement was performed by linear scanning potential (LSV) at a RDE rotation speed of 1600 rpm and a voltage scanning rate of 5 mV / s in the voltage range of 1000 rpm.

[0135] The mass activity (MA) value of the catalyst is 0.9V RHE The MA values ​​were measured using the linear scanning potential (LSV) method in a 0.1 M HClO4 aqueous solution saturated with high-purity oxygen gas at 1000 kJ / s. To measure the MA values, the kinetic current was calculated via the Koutecky-Levich equation (ik = (i × id) / (id - i). As is known, in the above equation, ik is the kinetic current, i is the measured current by the electrochemical analyzer, and id is the diffusion-limited current.

[0136] An accelerated stress test (AST) was conducted to test the durability of the catalyst. The AST was conducted by cyclic voltammetry (CV) in a 0.1 M HClO4 aqueous solution saturated with high-purity nitrogen gas at 0.6 to 1.0 V. RHE The voltage range was 100 mV / s and the voltage scan rate was 100 mV / s for 10,000 cycles. The durability of the catalyst was evaluated by comparing the ECSA values ​​before and after AST and the MA@0.9V values.

[0137] For comparison with the porous carbon bodies produced in the Examples, the crystallinity and pore characteristics of commercial carbon bodies were analyzed in the same manner as in the analysis of the porous carbon bodies. Furthermore, catalysts and half-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).

[0138] 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 half-cell fabricated using MH-18 (CNovel, TOYO TANSO) as a Pt support can be referred to as the electrochemical characteristics of MH-18. TM , TOYO TANSO) may be referred to as the cumulative delta graph of MH-18. For example, the porous carbon body prepared in Example 1, the catalyst prepared using the porous carbon body as a Pt support, and the electrochemical characteristics of the half-cell may be referred to as the porous carbon body of Example 1, the catalyst of Example 1, and the electrochemical characteristics of Example 1.

[0139] 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.

[0140] [Table 2]

[0141] Figure 1 shows the overlay graph of the porous carbon body of Example 2. Overlay graphs of comparative samples are also shown in Figure 2 (overlay graph of Li-435 sample) and Figure 3 (overlay graph of MH-18 sample).

[0142] All of the porous carbon materials prepared in the examples had three intersections in the 2-50 nm range on the superimposed graph, resulting in two closed curves, as shown in Figure 1. On the other hand, all of the comparative samples had either no intersections or more than three intersections (five intersections) in the 2-50 nm range, similar to Figures 2 and 3.

[0143] The number of intersections, the position of P1 (nm), the position of P2 (nm), the position of P3 (nm), and the difference between the positions of P3 and P2 (P3-P2, nm) in the porous carbon bodies prepared in the examples are summarized in Table 3. The area of ​​the closed curve of P1-P2 (A cl1 ), the area of ​​the closed curve between P2 and P3 (A cl2 ) and area ratio (A cl2 / A cl1 ) are summarized in Table 4.

[0144] [Table 3]

[0145] [Table 4]

[0146] Figure 4 shows the cumulative delta graph of the porous carbon body of Example 2. The cumulative delta graphs of the comparative samples are also shown in Figure 5 (cumulative delta graph of Li-435 sample) and Figure 6 (cumulative delta graph of MH-18 sample).

[0147] The porous carbon materials prepared in the Examples all had cumulative delta graphs located in the positive y-axis region without intersecting with the x-axis, and consisted of four regions: a first decrease region, a first increase region, a second decrease region, and a second increase region, with one maximum point formed between the first increase region and the second decrease region, as shown in Figure 4. In contrast, the comparative samples all had cumulative delta graphs that simply increased, intersected with the x-axis (including 0 and negative values), or had two or more maximum points, similar to Figures 2 and 3.

[0148] In the porous carbon body produced in the examples, the minimum value of the cumulative delta graph (cm) in the range of 2 to 30 nm on the cumulative delta graph 3 / g, Min), the boundary position between the first increase region and the second decrease region (nm, 1-2 boundary), and the boundary position between the second decrease region and the second increase region (nm, 2-2 boundary) are summarized in Table 5.

[0149] [Table 5]

[0150] The electrochemical characteristics (electrochemical specific surface area ESCA and mass activity MA) of half cells equipped with catalysts prepared using the porous carbon bodies prepared in the examples and the carbon bodies of the comparative samples are summarized in Table 6 (initial) and Table 7 (after AST), and the ESCA retention rate and MA retention rate after the accelerated stress test are also shown.

[0151] [Table 6]

[0152] [Table 7]

[0153] The above-described 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~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, Physical property 3: A superimposed graph obtained by superimposing a first pore volume distribution graph obtained by a nitrogen adsorption isotherm and a second pore volume distribution graph obtained by a nitrogen desorption isotherm according to the BJH method based on the Harkins-Jura equation has three intersections, P1, P2, and P3, in the direction of increasing pore diameter in the pore diameter range of 2 to 50 nm.

2. The porous carbon body according to claim 1, wherein the P3 is located in a pore diameter range of more than 10 nm to 40 nm.

3. The porous carbon body according to claim 2, wherein the P2 is located in a pore diameter range of 5 nm to 25 nm.

4. 2. The porous carbon body according to claim 1, wherein in the superimposed graph, an area ratio obtained by dividing the area of ​​the closed curve from P2 to P3 by the area of ​​the closed curve from P1 to P2 is 2.5 or less.

5. The porous carbon body according to claim 1 , further satisfying the following property 4: Physical property 4: In the first pore cumulative volume distribution obtained by a nitrogen adsorption isotherm and the second pore cumulative volume distribution obtained by a nitrogen desorption isotherm according to the BJH method based on the Harkins-Jura equation, the value obtained by subtracting the second pore cumulative volume distribution value from the first pore cumulative volume distribution value according to pore diameter is a positive value in the pore diameter range of 2 to 30 nm.

6. 6. The porous carbon body according to claim 5, wherein a cumulative delta graph, which is a graph of a value obtained by subtracting a second pore cumulative volume distribution value from a first pore cumulative volume distribution value according to the pore diameter, sequentially includes a first decrease region, a first increase region, a second decrease region, and a second increase region in a direction in which the pore diameter increases.

7. The porous carbon body according to claim 6, wherein the boundary between the first increasing region and the second decreasing region is located in a pore diameter range of 5 nm to 20 nm.

8. The porous carbon body according to claim 6, wherein the boundary between the second decreasing region and the second increasing region is located in a pore diameter range of 10 nm to 30 nm.

9. The positive value is 0.05 cm ３ The porous carbon body according to claim 5 , wherein the value of the porous carbon body is equal to or greater than 1 / g.

10. The porous carbon body according to any one of claims 1 to 9, further satisfying the following physical property 5: Physical property 5: Average layer spacing (d ００２ ) is 0.335 nm to 0.350 nm.

11. The porous carbon body according to any one of claims 1 to 9, further satisfying the following physical property 6: Physical property 6: Lattice constant in the a-axis direction measured by X-ray diffraction method (L ａ ) is 4nm to 10nm.

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

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

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

15. A polymer electrolyte membrane fuel cell comprising the catalyst of claim 13.

Images