Porous carbon supports and catalysts 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 catalyst for fuel cells using the same.

[0002] The national research and development project that supported this invention is as follows. Problem ID number 1711182201 Problem number 2021M3H4A1A02049886 Department name Ministry of Science and ICT Name of the problem management (specialty) organization Korea Foundation for Advanced Studies Research project name Development of nano material technology / leading type Research problem name Development of synthesis technology for highly crystalline porous carbon support based on low-temperature process Contribution rate 0.5 Name of the problem execution organization The Carbon Studio Co., Ltd. Research period 2023-01-01~2023-12-31

[0003] Problem ID number 1415186363 Problem number 20020437 Department name Ministry of Trade, Industry and Energy Name of the problem management (specialty) organization Korea Institute for Advancement of Technology Research project name Development of nano-fusion innovative product technology Research problem name Development of fuel cell module technology for hydrogen electric vehicles with a platinum alloy nano catalyst production base with a platinum usage of 0.2 g / kW or less in the MEA Contribution rate 0.5 Name of the problem execution organization The Carbon Studio Co., Ltd. Research period 2023-01-01~2023-12-31

Background Art

[0004] As an energy source that can replace fossil energy, polymer electrolyte membrane fuel cells (PEMFCs) with high energy efficiency and environmental friendliness have attracted attention.

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

[0006] A crucial factor determining the performance of a fuel cell is the catalyst used to form the electrodes (anode and cathode) of the MEA, which is generally used by supporting platinum-based catalyst particles on a porous carbon support.

[0007] Porous carbon supports not only support catalyst particles but also influence catalytic activity. For example, the specific surface area of ​​the carbon support determines the amount of catalyst particles that can be supported, and the degree of degradation of the carbon support affects the overall stability and durability of the fuel cell. Above all, the pore structure of the carbon support greatly influences the degree of dispersion of supported catalyst particles, the size of the catalyst particles, the position of catalyst particles within the support, gas diffusivity, the degree of flooding, and power generation performance under fuel cell operating conditions (for example, high temperature and low humidity conditions). As a result, various studies are being conducted to control the size and structure of the pores of carbon supports.

[0008] However, there are still various interpretations, including some that contradict each other, regarding the advantageous pore structure of porous carbon supports, and an advantageous pore structure has not yet been established. [Overview of the project] [Problems that the invention aims to solve]

[0009] One aspect of this disclosure is to provide a porous carbon material that can exhibit improved catalyst durability when used as a catalyst support for fuel cells.

[0010] The problems addressed by the present invention are not limited to those described above. Anyone with ordinary skill in the art to which the present invention pertains should have no difficulty understanding further problems addressed by the present invention from the entirety of the specification. [Means for solving the problem]

[0011] The porous carbon material disclosed in this document satisfies the following physical properties: Physical property 1: The surface area of ​​pores with a size of 2 nm to 5 nm obtained by nitrogen desorption isotherm (N2 desorption isotherm) based on the Barrett-Joyner-Halenda (BJH) method on a Harkins-Jura basis is 100 m². 2 / g~500m 2 / g, Physical property 2: The surface area of ​​pores with a size of 2 nm to 100 nm obtained by nitrogen desorption isotherm based on the BJH method on a Harkins-Jura substrate is 200 m². 2 / g~1500m 2 / g, Physical property 3: Based on the Harkins-Jura-based BJH method, the superimposed graph, which combines the first pore volume distribution graph obtained by nitrogen adsorption isotherms and the second pore volume distribution graph obtained by nitrogen desorption isotherms, has three intersection points P1, P2, and P3 sequentially in a manner that increases the diameter in the pore diameter range of 2 to 50 nm.

[0012] In one specific example, the above-mentioned P3 can be located in a pore diameter range of over 10 nm to 40 nm or less.

[0013] In one specific example, P2 can be located in a pore diameter range of 5 nm to 25 nm.

[0014] In one specific example, in the superimposed graph described above, 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] A porous carbon body according to one specific example can further satisfy the following physical property 4. Physical property 4: Based on the BJH method on a Harkins-Jura substrate, the value obtained by subtracting the second pore cumulative volume distribution value from the first pore cumulative volume distribution value based on pore diameter has a positive value in the pore diameter range of 2 to 30 nm.

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

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

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

[0019] In one specific example, the above positive value is 0.05 cm. 3 It may be more than / g.

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

[0021] A porous carbon body according to one specific example can further satisfy the following physical property 6. Physical property 6: Lattice constant in the a-axis direction (L) measured by X-ray diffraction. a ) is 4nm to 10nm.

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

[0023] The fuel cell catalyst according to one disclosure includes the porous carbon body described above and the catalytic material supported on the porous carbon body described above.

[0024] The catalyst layer for fuel cells according to one disclosure contains the above-mentioned catalyst and ionomer.

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

[0026] The porous carbon material disclosed herein exhibits improved catalyst durability when used as a catalyst support in fuel cells, due to its porous structure containing an appropriate amount of bottleneck-shaped pores.

[0027] One specific example of a porous carbon body has a porous structure containing an appropriate amount of bottleneck-shaped pores with a wide range of sizes, and can exhibit improved catalytic activity and durability when used as a catalyst support in a fuel cell.

[0028] The diverse yet significant advantages and effects of the present invention are not limited to those described above and can be more easily understood in the process of describing specific embodiments of the present invention. [Brief explanation of the drawing]

[0029] [Figure 1] This figure shows a superposition graph of a porous carbon material produced by one embodiment. [Figure 2] This diagram shows a superimposed graph of comparison samples. [Figure 3] This diagram shows a superimposed graph of comparison samples. [Figure 4] This is a diagram showing the cumulative delta graph of a porous carbon body produced by one embodiment. [Figure 5]This diagram shows the cumulative delta graph of the comparison sample. [Figure 6] This diagram shows the cumulative delta graph of the comparison sample. [Modes for carrying out the invention]

[0030] The terms used in this invention are for illustrative purposes only and are not intended to limit the invention. Furthermore, the singular forms used herein also include plural forms unless the relevant definition clearly indicates otherwise.

[0031] As used in the specification, "includes" specifies the configuration and does not exclude the existence or addition of other configurations.

[0032] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in the dictionary are to be interpreted in accordance with the relevant technical literature and the content of the present disclosure.

[0033] The terms "first," "second," etc., used herein and in the appended claims are not limited in meaning but are used to distinguish one component from another.

[0034] In this specification and the appended claims, fuel cells may include polymer electrolyte membrane fuel cells (PEMFCs), phosphate fuel cells (PAFCs), alkali fuel cells (AFCs), molten carbonate fuel cells (MCFCs), or solid oxide fuel cells (SOFCs). However, a porous carbon body, as described in one specific example, can exhibit improved durability and catalytic activity when supporting a catalyst, and can therefore be used more effectively in fuel cells where expensive catalysts are typically used. Examples of such fuel cells include polymer electrolyte membrane fuel cells (PEMFCs) and phosphate fuel cells (PAFCs).

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

[0036] In this specification and the appended claims, a nitrogen adsorption / desorption isotherm means an isotherm formed by combining the isotherm of the nitrogen adsorption process (nitrogen adsorption isotherm) and the nitrogen desorption process (nitrogen desorption isotherm) obtained by nitrogen adsorption measurement of a porous carbon body. The x-axis represents the relative nitrogen pressure (P / P0) and the amount of nitrogen adsorbed (cm²). 3 In detail using the graph of the y-axis ( / g STP), the nitrogen adsorption / desorption isotherm has the same x-axis and the same y-axis, meaning the graph shows the nitrogen adsorption isotherm and nitrogen desorption isotherm together. Hysteresis can be described as a form in which the nitrogen adsorption isotherm and nitrogen desorption isotherm are separated from each other. In other words, hysteresis can be described as a certain region in which the amount of nitrogen adsorbed differs at the same relative pressure due to the difference between the nitrogen adsorption process and the nitrogen desorption process.

[0037] The inventors conducted research on porous carbon materials for fuel cell catalyst supports that satisfy both high porosity and high crystallinity, which are known to be trade-off properties. In the course of continuing this research, they discovered that bottleneck pores in porous carbon materials for fuel cell catalyst supports differ from those conventionally known and are advantageous in improving the durability and catalytic activity of fuel cell catalyst materials. Based on this discovery, they deepened their research and established a pore structure that can improve the durability and activity of catalyst materials while preventing the adverse effects that may occur due to bottleneck pores, thereby completing the present invention.

[0038] The porous carbon material disclosed herein satisfies the following physical properties 1, 2, and 3: Physical property 1: The surface area of pores with a size of 2 nm or more and 5 nm or less obtained from the nitrogen desorption isotherm based on the BJH (Barrett-Joyner-Halenda) method on the Harkins-Jura basis is 100 m 2 / g to 500 m 2 / g, Physical property 2: The surface area of pores with a size of 2 nm or more and 100 nm or less obtained from the nitrogen desorption isotherm based on the BJH method on the Harkins-Jura basis is 200 m 2 / g to 1500 m 2 / g, Physical property 3: Based on the BJH method on the Harkins-Jura basis, the superposition graph in which 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 has three intersections P1, P2, and P3 in the order of increasing diameter in the pore diameter range of 2 to 50 nm.

[0039] The pore region with a size of 2 nm or more and 5 nm or less is the region that mainly affects the loading of the catalyst substance, and the characteristics of the catalyst substance supported on the porous carbon body can be determined by the specific surface area of the 2 - 5 nm pore region.

[0040] When the porous carbon body satisfies Physical property 1, the catalyst substance can be supported on the porous carbon body in the form of extremely fine particles of several nanometers (for example, 1 - 3 nm), the aggregation of the catalyst substance can be suppressed, and the stability and durability of the catalyst can be improved.

[0041] The porous carbon body according to a specific example has a surface area of pores with a size of 2 nm or more and 5 nm or less obtained from the nitrogen desorption isotherm based on the BJH (Barrett-Joyner-Halenda) method on the Harkins-Jura basis of 100 m 2 / g to 500 m 2 / g, specifically 100 m2 / g~400m 2 / g, more specifically 100m 2 / g~350m 2 It can satisfy the / g requirement.

[0042] Pore ​​regions ranging in size from 2 nm to 100 nm are involved in the movement of reaction products such as water in fuel cells, and the specific surface area of ​​these 2 nm to 100 nm pore regions can affect various characteristics of the fuel cell. By satisfying physical property 2, the reaction products of the fuel cell can be moved smoothly during operation.

[0043] In one specific example, a porous carbon material was obtained by nitrogen desorption isotherm analysis based on the Harkins-Jura-based BJH method, with pores ranging in size from 2 nm to 100 nm having a surface area of ​​200 m². 2 / g~1500m 2 / g, for details 200m 2 / g~1000m 2 / g, more specifically 200m 2 / g~800m 2 / g, for more details 220m 2 / g~700m 2 It can satisfy the / g requirement.

[0044] A porous carbon body based on one specific example can satisfy the above-mentioned physical properties 1 and 2, as well as the following physical property 3.

[0045] Physical property 3: Based on the Harkins-Jura-based BJH method, the superimposed graph obtained by superimposing the first pore volume distribution graph obtained by nitrogen adsorption isotherms and the second pore volume distribution graph obtained by nitrogen desorption isotherms has three intersection points P1, P2, and P3 sequentially in the direction of increasing diameter within the pore diameter range of 2 to 50 nm.

[0046] As is well known, nitrogen adsorption / desorption isotherms show the relationship between nitrogen partial pressure and nitrogen adsorption amount, and the amount of adsorption (cm³) corresponds to the relative pressure (P / P0). 3 It has a value of ( / g STP). By the BJH method on a Harkins-Jura substrate, the nitrogen relative pressure (P / P0) of the adsorption / desorption isotherm is expressed as the pore diameter (nm), and the nitrogen adsorption amount (cm 3 ( / g STP) stomatal volume (cm³) 3 A stomatal volume distribution graph can be obtained by converting it to ( / g). Therefore, the stomatal volume distribution graph is a graph of stomatal volume by stomatal diameter (size), and specifically the x-axis is stomatal diameter (nm), which is a logarithmic scale, and the stomatal volume (cm) is obtained. 3 This is a semi-log-scale graph with a y-axis of ( / g). The first pore volume distribution graph is a semi-log-scale pore volume distribution graph obtained from nitrogen adsorption isotherms obtained by nitrogen adsorption using the BJH method on a Harkins-Jura basis, and the second pore volume distribution graph may be a semi-log-scale pore volume distribution graph obtained from nitrogen desorption isotherms obtained by nitrogen desorption using the BJH method on a Harkins-Jura basis. The superimposed graph has the same x-axis (nm) and the same y-axis (cm) on a log-scale. 3 The value in / g) can be interpreted as a semi-logarithmic scale graph showing both the first and second stomatal volume distribution graphs together.

[0047] Physical property 3 is a property that can be satisfied when a porous carbon material contains a considerable amount of bottleneck-shaped pores (hereinafter commonly referred to as bottleneck pores) and simultaneously contains bottleneck pores over a wide range of sizes. Only when a porous carbon material satisfies physical property 3 can the desired advantages of bottleneck pores be obtained while suppressing the adverse effects of the bottleneck shape.

[0048] More specifically, if there are no intersections in the pore diameter range of 2-50 nm on the superposition graph, or if there are one or two intersections, the degree of bottleneck pore development is minimal and unlikely to have a significant impact when used as a catalyst support. On the other hand, if there are four or more intersections in the pore diameter range of 2-50 nm on the superposition graph, mesopores including bottleneck pores develop excessively, making mass transfer including the gas phase within the carbon body difficult, easily causing flooding, and making it difficult to prevent the adverse effects caused by bottleneck pores.

[0049] The positions of P2 and P3 in the superimposed graph are indicators related to the size of bottleneck pores. More specifically, in the superimposed graph, P3 is an indicator mainly related to the size of the internal pore region in bottleneck pores, and P2 is an indicator mainly related to the size of the bottleneck region in bottleneck pores. Furthermore, the positions of P3 and P2 are indicators of the degree of bottleneck morphology, i.e., the degree to which it is close to a closed pore.

[0050] In one specific example, the porous carbon body can have P3 on the superposition graph located between 10 nm and 40 nm, specifically within a pore diameter range of 11 nm to 35 nm. The P3 position between 10 nm and 40 nm, specifically between 11 nm and 35 nm, ensures that the catalyst is evenly supported within the bottleneck pores, while providing sufficient space for catalyst support to prevent aggregation within the pores. Furthermore, the reactant gaseous oxygen and the product water can be smoothly transferred and discharged through the available space. In conjunction with or independently of this, P2 on the superposition graph can be located between 5 nm and 25 nm, specifically within a pore diameter range of 5 nm to 20 nm. The P2 position between 5 nm and 25 nm, specifically between 5 nm and 20 nm, effectively prevents direct contact between the catalyst and ion transfer media (e.g., ionomers) that have entered through the meso or macropores of the porous carbon body. Furthermore, the phenomenon of catalyst material not escaping to the outside of the pores during the fuel cell operation process can be effectively prevented.

[0051] In one specific example, the difference between the positions of P3 and P2 (P3 position - P2 position) can be 5 nm to 20 nm, specifically 5 nm to 15 nm. The bottleneck pore having the aforementioned positional difference between P3 and P2 prevents direct contact between the ion transfer medium and the catalyst without hindering the transfer and efflux of reactants and products such as oxygen and water due to the bottleneck configuration.

[0052] In one specific example, in the region from x-axis reference 2nm-P1, the first pore volume distribution graph using nitrogen adsorption isotherms can be located above (with a larger y value) the second pore volume distribution graph using nitrogen desorption isotherms. In the region from x-axis reference P1-P2, the second pore volume distribution graph using nitrogen desorption isotherms can be located above the first pore volume distribution graph using nitrogen adsorption isotherms. In the region from x-axis reference P2-P3, the first pore volume distribution graph using nitrogen adsorption isotherms can be located above the second pore volume distribution graph using nitrogen desorption isotherms. In the region from x-axis reference P3-50nm, the second pore volume distribution graph using nitrogen desorption isotherms can be located above the first pore volume distribution graph using nitrogen adsorption isotherms.

[0053] In other words, the three intersection points of P1, P2, and P3 can correspond to the boundary points of two regions in the direction in which the pore diameter increases: 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] With these three intersections of P1, P2, and P3, the superimposed graph can have a first closed curve formed by the second stomatal volume distribution graph located at the top and the first stomatal volume distribution graph located at the bottom, with the x-axis reference P1-P2, and a second closed curve formed by the first stomatal volume distribution graph located at the top and the second stomatal volume distribution graph located at the bottom, with the x-axis reference P2-P3.

[0055] In a superimposed graph, the area ratio obtained by dividing the area of ​​the closed curve from P2 to P3 (second closed curve) 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 ) is the area of ​​the first closed curve (A cl1 Area ratio (A) divided by cl2 / A cl1 The area ratio (A) can be 0.01 to 2.50, more 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 By satisfying the following conditions, when a porous carbon body is used as a support for carrying a catalytic material, the catalyst can have an improved electrochemical specific surface area (ESCA), and along with this, it can have significantly improved durability. Although not necessarily limited to this type of analysis, A in the superimposed graph cl2 / A cl1 The area ratio may be a physical property related to the size distribution of the bottleneck region and the size distribution of the internal pore region of the bottleneck pores included in the pore structure of a porous carbon material. The area ratio described above can indicate that a group of pores having a bottleneck morphology (bottleneck pore group) is formed by bottleneck pores and internal pores having a considerably wide size distribution.

[0056] A porous carbon body according to one specific example can further satisfy the following physical property 4.

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

[0058] The cumulative stomatal volume distribution was calculated using the BJH method based on the Harkins-Jura equation, where the relative nitrogen pressure (P / P0) of the nitrogen adsorption / desorption isotherm is set to the stomatal diameter (nm), and the amount of nitrogen adsorbed (cm³) accumulated up to each stomatal diameter was calculated.3 ( / g STP) to cumulative pore volume (cm³) 3 It may be obtained by converting to ( / g). In other words, the cumulative stomatal volume distribution may be obtained by accumulating the stomatal volume up to each stomatal diameter based on the stomatal volume distribution graph described above. Therefore, the cumulative stomatal volume distribution is also on a logarithmic scale, with the x-axis representing stomatal diameter (nm) and the cumulative stomatal volume (cm²). 3 This may be a semi-logarithmic scale graph with the y-axis of ( / g). The first cumulative stomatal volume distribution may be calculated from a stomatal volume distribution graph obtained by nitrogen adsorption isotherms, and the second cumulative stomatal volume distribution may be calculated from a stomatal volume distribution graph obtained by nitrogen desorption isotherms.

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

[0060] More specifically, the value obtained by subtracting the cumulative volume distribution value of the second stoma from the cumulative volume distribution value of the first stoma (hereinafter referred to as the cumulative volume difference) can more directly reflect the size distribution of bottleneck stomatous structures that form bottleneck stoma groups.

[0061] When the pore structure of a porous carbon material contains a significant amount of bottleneck pores, as well as bottleneck pores and internal pores of various sizes, the cumulative volume difference can be positive in the total pore diameter range of 2 to 30 nm. Specifically, the cumulative volume difference in the total pore diameter range of 2 to 30 nm is 0.05 cm³. 3 / g or more, more specifically 0.05-2.0cm 3 / g, more specifically 0.05~1.8cm 3 It can be / g. Bottleneck pores of various sizes are very advantageous in simultaneously improving catalytic activity, represented by electrochemical specific surface area (ESCA) and mass activity, and catalytic durability, represented by the rate of decrease in ESCA and the rate of decrease in mass activity.

[0062] As described above, the cumulative volume difference due to pore diameter can more directly reflect the size distribution of bottleneck pores that form bottleneck pore groups. More specifically, the graph of the cumulative volume difference due to pore diameter can be defined as a cumulative delta graph. Because it is a value of the cumulative volume difference due to pore diameter, the cumulative delta graph has a log-scale pore diameter (nm) on the x-axis and a cumulative volume difference (cm) on the cm. 3 This can be a semi-logarithmic scale graph with a y-axis of ( / g). In this case, the cumulative delta graph can have a pore diameter range of 2 to 30 nm.

[0063] In one specific example, the cumulative delta graph can sequentially include a first decreasing region, a first increasing region, a second decreasing region, and a second increasing region in the direction of increasing stomatal diameter, and can include them continuously.

[0064] In a cumulative delta graph, a decreasing region is the area where the value of the cumulative volume difference decreases as the stomatal diameter increases, while an increasing region is the area where the value of the cumulative volume difference increases as the stomatal diameter increases.

[0065] In detail, the cumulative delta graph may sequentially include a first decreasing region containing a pore diameter of 2 nm, a first increasing region, a second decreasing region, and a second increasing region containing a pore diameter of 30 nm, in the direction of increasing pore diameter within the pore diameter range of 2 to 30 nm. Therefore, the cumulative delta graph may have a maximum point corresponding to the boundary between the first increasing region and the second decreasing region, or it may have a single maximum point.

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

[0067] The morphology of the single maximum point in the cumulative delta graph described above may indicate that the porous carbon body contains bottleneck pores of various sizes, and at the same time, that the bottleneck pores are well-developed and uniform across a very wide range of pore sizes, and that it has a well-connected pore structure between the bottleneck pores present across this very wide range of pore sizes. Furthermore, it can 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 bottleneck pores and internal pore sizes of such a bottleneck structure.

[0068] The porous carbon material has a pore structure that includes bottleneck pores that are well interconnected and have a variety of sizes, are well developed uniformly across a very wide range of pore sizes, and have a pore structure that prevents aggregation, elution, and poisoning by ionsomers of the catalyst material, allowing for fine and uniform loading, and further improving both catalytic activity and catalyst durability. In addition, the pore structure, which includes bottleneck pores that are well interconnected and have a variety of sizes, is well developed uniformly across a very wide range of pore sizes, and allows for smooth and rapid supply of the gas phase to the particulate catalyst material and smooth and rapid discharge of the liquid phase derived from the fuel cell reaction, effectively preventing flooding. Specific examples of the gas phase include gases involved in the electrochemical reaction of a fuel cell, such as oxygen, air, and hydrogen, and specific examples of the liquid phase include liquids containing reaction products of the electrochemical reaction of a fuel cell, such as water; however, the present invention is not limited to specific gaseous and liquid substances.

[0069] A porous carbon body according to one specific example can further satisfy the following physical property 5.

[0070] Physical property 5: Average layer spacing (d) measured by X-ray diffraction. 002 ) is 0.335nm~0.350nm (002) Average layer spacing of the surface (d 002 ) is an indicator that directly shows the crystallinity of carbon that forms a porous carbon body. d 002This can be interpreted as meaning that the porous structure of a porous carbon body, including bottleneck pores, is formed by a carbon skeleton with excellent crystallinity.

[0071] Due to the excellent crystallinity of the carbon skeleton, porous carbon materials can possess superior oxidation resistance. Therefore, when porous carbon materials are used as catalyst supports in fuel cells, the catalyst can have improved durability.

[0072] In conjunction with or independently thereof, a specific porous carbon body may further satisfy the following physical property 6.

[0073] Physical property 6: Lattice constant in the a-axis direction (L) measured by X-ray diffraction. a ) refers to 4nm to 10nm, specifically 6nm to 10nm, more specifically 7nm to 10nm, and even more specifically 7.5nm to 10nm. Physical property 6 is also related to the crystallinity of the porous carbon body; a higher La value indicates that the carbon skeleton of the porous carbon body is formed of graphite with a wider hexagonal network. Satisfying physical property 6 of the porous carbon body is advantageous because it reduces the number of defect sites that are vulnerable to oxidation.

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

[0075] Physical property 7: The average number of graphene layers calculated by X-ray diffraction is 6-20, specifically 7-15, and more specifically 8-15. Physical property 7 is also related to the crystallinity of porous carbon bodies, and the average number of graphite layers is the lattice constant (L) in the c-axis direction. c ) to d 002 This value is calculated by adding 1 to the value obtained by dividing by [a certain factor], and it indicates that the larger the average number of graphite layers, the more the carbon skeleton of the porous carbon body is formed of thicker graphite crystals.

[0076] In one advantageous example, a porous carbon material can possess excellent crystallinity that satisfies all of physical properties 5, 6, and 7, along with the aforementioned porosity structure. When a porous carbon material possesses both the aforementioned porosity structure and crystallinity that satisfies all of physical properties 5, 6, and 7, it can exhibit excellent oxidation resistance, with a mass loss rate of 0% to 30% at 500°C to 700°C measured by thermogravimetric analysis (TGA), specifically at levels of 2% to 28%, 10% to 28%, 15% to 25%, 18% to 20%, or 21% to 23%.

[0077] Furthermore, if a porous carbon material possesses the aforementioned porosity structure and crystallinity satisfying all of physical properties 5, 6, and 7, it can exhibit oxidation resistance such that the temperature at which a 30% mass reduction relative to the raw material occurs in thermogravimetric analysis of the porous carbon support is high, specifically 705-730°C, 710-715°C, or 715-725°C. Experimentally, the thermogravimetric analysis of a porous carbon material can be measured according to ASTM E1131.

[0078] In one specific example, a porous carbon body can be an aggregate in which primary particles are randomly aggregated with each other, and the primary particles may include hollow particles. Thus, the pore structure of the porous carbon body described above may be formed by pores within the primary particles themselves, between primary particles, between parts of the aggregate and primary particles, between parts of the aggregate and parts of the aggregate, and between aggregates. The average primary particle diameter of the porous carbon body may be 10 nm to 30 nm. In this case, the average primary particle diameter may be measured according to ASTM D3849.

[0079] In one specific example, a porous carbon body may be doped with heterologous elements. These heterologous elements may include one or more elements selected from quasimetallics, nonmetallics (excluding carbon), and transition metals. Quasimetallics include one or more elements selected from B, Si, Ge, As, Sb, Te, and Po, while nonmetallics may include one or more elements selected from N, O, P, S, and Se. Transition metals may include one or more elements selected from metals belonging to groups 3 to 12, specifically metals belonging to periods 4 or 5 of groups 3 to 12 (for example, Co, Fe, Ni, Cu, Zn, Cr, V, Ti, Sc, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) and metals belonging to group lanthanum (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). When a porous carbon material is doped with heterologous elements, it can contain 0.05 to 5.00 mass% of the heterologous elements. Specifically, the porous carbon material can contain 0.05 to 5.00 mass% of quasimetallic elements, 0.05 to 0.50 mass% of nonmetallic elements, and / or 0.05 to 2.00 mass% of transition metals. Doping with heterologous elements can improve catalytic performance when used as a catalyst support in fuel cells.

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

[0081] A fuel cell catalyst according to one disclosure includes a support which is a porous carbon body as described above, and a catalytic substance supported on the support.

[0082] The catalytic material may include platinum-based catalysts, non-platinum catalysts, or mixtures thereof, which are known to catalyze oxidation reactions (e.g., oxidation of hydrogen) or reduction reactions (e.g., reduction of oxygen) that occur in fuel cells. Typical examples of platinum-based catalysts include platinum catalysts, alloy catalysts between platinum and precious metals (Au, Ag, Pd, Ru, Rh, Ir, Os, etc.), alloy catalysts between platinum and non-precious metals (Ni, Fe, Co, Cr, Cu, Mn, V, Ti, Ta, Nb, Mg, Sn, Bi, Pb, Al, Mo, Nb, Ta, Zr, Ru, Se, etc.), alloy catalysts between platinum, precious metals, and non-precious metals, composite catalysts of platinum-based metals and metal oxides, and core-shell catalysts of transition metal cores and platinum shells. Typical examples of non-platinum catalysts include non-platinum alloy catalysts such as Ru-Ir alloys and Pd-transition metal alloys, transition metal (Ni, Fe, etc.)-N catalysts, and transition metal (Ni, Fe, etc.)-NC catalysts. However, the porous carbon material described above is even more advantageous for supporting platinum catalysts by providing an effective pore structure through the support of catalytic materials having a size at the cluster or several nanometer level.

[0083] The catalyst material supported on the porous carbon body may be in the form of nanoparticles, and in one specific example, it may be in the form of parts having a size 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 catalytic substance supported.

[0085] The present invention includes a fuel cell catalyst layer containing the porous carbon material described above.

[0086] A catalyst layer for a fuel cell according to one 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 catalyst described above.

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

[0089] The ionomer can be any polymer known to conduct ions involved in the fuel cell reaction. Specifically, the ionomer can be a hydrogen ion-conducting ionomer. Examples of hydrogen ion-conducting ions include known sulfonated block copolymers, perfluorinated polymers having sulfonate groups on their side chains, or sulfonated aromatic polymers. Commercial ionsomers may be used, and examples of such commercial products include Nafion® (manufactured by DuPont), Aciplex® (manufactured by Asahi Kasei Corporation), and Flemion® (manufactured by Asahi Glass Co., Ltd.).

[0090] The amount of catalyst contained in the catalyst layer is sufficient as long as the desired catalytic activity can be stably realized during the electrochemical reaction of the fuel cell, and can be the amount of catalyst normally contained in the catalyst layer of a fuel cell. As a practical example, the catalyst layer can contain 10 to 90% by weight of the catalyst, specifically 30 to 90% by weight, but the present invention is not limited by the specific catalyst content in the catalyst layer.

[0091] If necessary, the catalyst layer may further contain a carbon material along with the catalyst and ionomer described above. The carbon material may include the porous carbon material described above without the catalyst, particulate conductive carbon material, carbon material with one-dimensional nanostructures (e.g., carbon nanotubes and carbon fibers), carbon material with two-dimensional nanostructures (e.g., graphene, reduced graphene oxide, graphene oxide), or mixtures thereof.

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

[0093] A membrane-electrode assembly according to one disclosure may include an anode, a cathode, and an electrolyte membrane interposed between the anode and the cathode. The anode may include a first gas diffusion layer and a first catalyst layer, and the cathode may include a second gas diffusion layer and a second catalyst layer. In this case, the first catalyst layer of the anode and the second catalyst layer of the cathode may be positioned in contact with the electrolyte membrane.

[0094] At least one of the first and second catalyst layers may contain the porous carbon material described above or the catalyst described above. Substantially, at least one of the first and second catalyst layers may be the fuel cell catalyst layer described above.

[0095] If necessary, the anode and cathode may be further provided with a microporous layer between the gas diffusion layer and the catalyst layer for improved water repellency, but the present invention is not limited to the specific structure of the film-electrode junction.

[0096] The gas diffusion layer can be any material commonly used in the field of fuel cells. Typical examples of gas diffusion layers include polyethylene terephthalate with water-repellent properties and carbon paper, but are not limited to these.

[0097] The electrolyte membrane can be any known membrane that is commonly used in the field of fuel cells for the conduction of the desired ions. In practical terms, the electrolyte membrane may be a hydrogen ion conductive electrolyte membrane. Typical examples of hydrogen ion conductive electrolyte membranes include sulfonated block copolymers, perfluorinated polymers having sulfonate groups on the side chains, or sulfonated aromatic polymers. Typical examples of commercial products include Nafion® (manufactured by DuPont), Aciplex® (manufactured by Asahi Kasei Corporation), and Flemion® (manufactured by Asahi Glass Co., Ltd.).

[0098] The present invention includes a fuel cell comprising 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 large number of unit cells are stacked, with the above-described membrane electrode assembly serving as the unit cell. In this stack, each unit cell can be positioned between separators in which a flow channel is formed.

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

[0101] A specific example of a method for producing a porous carbon body may include the steps of: S1) heat-treating a carbon raw material at 1000°C to 3000°C to remove impurities and crystallize it; S2) pre-treating the carbon raw material, from which impurities have been removed and which has been crystallized, at a temperature of 500°C to 1000°C for 200 to 500 minutes in an atmosphere containing at least one heterogeneous element selected from the group consisting of boron, carbon, nitrogen, oxygen, phosphorus, and sulfur to introduce activated sites, which are sites doped with the heterogeneous element; S3) mixing an additive containing an organic surfactant with the carbon raw material into which the activated sites have been introduced, and then activating the carbon raw material by removing the heterogeneous element through heat treatment at 500°C to 1000°C for 200 to 400 minutes; S4) washing and drying the activated carbon raw material; and S5) heat-treating the washed and dried activated carbon raw material at 1200 to 1700°C in an inert atmosphere to close the pores.

[0102] Steps S1) to S4) are processes primarily aimed at improving the crystallinity of the carbon raw material and simultaneously creating a large number of meso and macropores, while step S5) may be a process that closes the openings of the pores formed in steps S1) to S4) to change the pore morphology to bottleneck pores.

[0103] In detail, after highly crystallizing the carbon raw material in step S1), a large amount of heterogeneous elements can be inserted into the carbon molecular structure in step S2), allowing for the formation of high-density unstable sites (sites with relatively high energy) within the highly crystalline carbon. During the activation step (step S3), relatively high-frequency activation reactions are induced at the unstable sites formed in the highly crystalline carbon structure, improving crystallinity and yield. Consequently, the unstable sites act as sites for pore formation, enabling the production of a carbon body that simultaneously satisfies both porosity and high crystallinity, with well-developed mesopores and macropores. Subsequently, by converting the pores formed in the carbon body into a bottleneck morphology through high-temperature heat treatment in step S5), a porous carbon body with a well-developed bottleneck pore structure across a wide range of sizes can be produced.

[0104] In detail, step S1) is a process in which impurities are removed from the carbon raw material by heat treatment and crystallization, which allows foreign elements to effectively penetrate into the interior of the carbon raw material in step S2). Here, impurities are substances other than carbon that are present on the surface or inside the carbon raw material, and examples based on substance may include petroleum residues and other functional groups, or examples based on element may include elements other than carbon (boron, carbon, nitrogen, oxygen, phosphorus, sulfur, etc.), but are not limited to these. In step S1), the lattice constant of the carbon raw material increases, and crystallization can be carried out in part or all of the raw material.

[0105] In one specific example, the carbon raw material may be amorphous carbon such as hard carbon such as cellulose, phenolic resin, and isotropic pitch, and soft carbon such as mesophase pitch and needle-shaped coke; or crystalline carbon such as artificial graphite and natural graphite; and more specifically, amorphous carbon, and more specifically, soft carbon. Soft carbon exhibits relative anisotropy to hard carbon, and the planes of the carbon layers are arranged parallel to each other, allowing crystallization, i.e., graphitization, to be carried out by heat treatment at 1000°C or higher. Depending on the case, the carbon raw material may include CNT (carbon nanotube), CNF (carbon nanofiber), etc.

[0106] Step S1) can be carried out at 1000°C to 3000°C for 10 minutes or more under vacuum or in an inert gas atmosphere (such as nitrogen, argon, neon, or helium). These conditions are necessary for crystallizing carbon while removing impurities other than carbon present in the carbon raw material. More specifically, step S1) can be carried out at 1000°C to 2000°C, more specifically 1000 to 1800°C, for 10 to 100 minutes under vacuum or in an inert gas atmosphere.

[0107] Step S2) is a process in which a predetermined heterologous element is introduced into a carbon raw material that has been crystallized after impurities have been removed. In this process, the carbon raw material can be selectively replaced with the heterologous element starting from the less crystalline parts inside. The points where the heterologous element is introduced can later become the starting points of the reaction in the activation process and can also act as points where pores are formed.

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

[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] Step S3) is a process in which the heterogeneous element inserted in the pretreatment step acts as a reaction initiation point to form pores. The reaction between the heterogeneous element and the additive in step S3) can form a microporous structure in which mesopores of a micrometer to several nanometers in size are mainly developed. Furthermore, as the heterogeneous element doped into areas with weak crystallinity is removed by the activation process, crystallinity improves and pores can be formed, so that a carbon material exhibiting high crystallinity while having a highly porous structure can ultimately be produced.

[0111] A mixture of carbon raw material with introduced activation sites and additives 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 carbon raw material with introduced activation sites. More 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 carbon raw material with introduced activation sites.

[0112] The alkali metal hydroxide may be one or more 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 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) can be carried out at 500°C to 1000°C for 200 to 400 minutes in an inert gas atmosphere. More specifically, it can be carried out at 600 to 900°C for 250 to 400 minutes.

[0114] Step S4) is the step of washing and drying the activated carbon raw material obtained in step S3). Washing can be carried out using an acid, base, water, etc., until the pH of the aqueous dispersion of the carbon raw material is 5 to 9, more specifically, 6 to 8. Drying can be carried out at a temperature of 70 to 120°C and atmospheric pressure for 10 to 20 hours, followed by a temperature of 80 to 150°C and vacuum conditions for 1 to 5 hours, but is not limited to this. Drying in step S4) can be carried out under conditions that can sufficiently remove moisture from the carbon material (intermediate product).

[0115] The pore closure process in step S5) can be carried out under vacuum or in an inert gas atmosphere (nitrogen, argon, neon, helium, etc.) at 1200-1700°C for 10-1500 minutes. Specifically, step S5) can be carried out under vacuum or in an inert gas atmosphere at 1200-1600°C for 10-1200 minutes. During the pore closure process in step S5), the heating rate can be at the level of 1°C / min-10°C / min, and cooling after the pore closure process can be air-cooled.

[0116] (Example 1) A carbon raw material (Li-435, Denka Company Limited) was crystallized by heating it at 1000°C for 30 minutes under an argon atmosphere. Afterward, a mixture of oxygen and nitrogen (50% oxygen by volume, 50% nitrogen by volume) was supplied to the crystallized carbon raw material at a flow rate of 300 sccm, and the material was heat-treated at 600°C for 5 hours to introduce activation sites. Following this, 1 part by weight of organic surfactant (Triton X-100), 1 part by weight of potassium hydroxide, and 3 parts by weight of neutral water were added to 100 parts by weight of the carbon raw material with introduced activation sites. The mixture was stirred for 300 minutes, then dried with hot air and mixed. The resulting mixture was then heat-treated (activated) at 700°C for 300 minutes under a nitrogen atmosphere. Hydrochloric acid, ammonia water, and neutral water were sequentially added to the activated sample, stirred for at least 30 minutes each, and then washed by vacuum filtration. During the washing process, the hydrochloric acid and ammonia water steps were carried out once each. Hydrochloric acid was added in an amount equal to 1:1 the weight of the potassium hydroxide used previously, and ammonia water was added in an amount equal to 1:1 the weight of the hydrochloric acid used previously. The washing process with neutral water was repeated until the pH of the liquid reached a range of 6-8 during stirring. Once the pH reached the target, the material was dried at 120°C and atmospheric pressure for at least 12 hours, followed by an additional drying at 120°C and under vacuum conditions for at least 1 hour. After this, the carbon material recovered after the additional drying was heat-treated in a nitrogen atmosphere at 1600°C for 450 minutes (pore closure treatment, heating rate = 5°C / min, air cooling) to produce a porous carbon material.

[0117] (Examples 2-4) A porous carbon body was produced in the same manner as in Example 1, except that the pore closure treatment was performed under the conditions shown in Table 1.

[0118] [Table 1]

[0119] The manufactured porous carbon material was analyzed under the following conditions.

[0120] Nitrogen adsorption / desorption measurement Nitrogen adsorption / desorption isotherms are obtained by measuring the change in nitrogen adsorption onto a porous carbon material 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] In detail, in addition to ASTM D6556, the preparation of the sample to obtain nitrogen adsorption / desorption isotherms followed the following: 1) Weigh out 300 mg of porous carbon sample, 2) Dry the sample under a vacuum of 0.1 Torr or less and at 200°C for 12 hours. 3) Nitrogen adsorption / desorption isotherms 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 nitrogen adsorption / desorption isotherms were as follows: Nitrogen adsorption gas, liquid nitrogen at a temperature of 77K, relative pressure (P / P0) measurement accuracy of 0.02, relative pressure (P / P0) range of 0 to 1.

[0124] Harkins-Jura substrate BJH method Using the BJH method, the relative nitrogen pressure (P / P0) of the adsorption / desorption isotherm is converted to the pore size (nm), and the amount of nitrogen adsorbed (cm³) is converted to the nitrogen adsorption amount (cm³). 3 ( / g STP) stomatal volume (cm³) 3 The distribution of pore size was obtained by converting to ( / g). In this process, a correction using the Harkins and Jura thickness curve was applied when converting relative pressure to pore size. In addition, the standard BJH correction, Faas correction, was applied along with the Harkins and Jura thickness curve. For adsorption isotherms, the conversion to pore size and pore volume was performed from the pore size range of 1.7 to 300 nm, and for desorption isotherms, from the pore size range of 2.0 to 50 nm.

[0125] X-ray diffraction measurement The X-ray diffraction patterns of porous carbon materials were obtained using a standard X-ray diffraction analyzer (for example, RIGAKU, SmartLab SE) under the following measurement conditions, applying the ASTM D5357 standard: 0.5g porous carbon powder, Cu Kα radiation, scan range of 10-70°, scan speed of 5.0° / min, scan step size of 0.03°.

[0126] X-ray diffraction patterns of porous carbon materials: d002, La, Lc d 002 Bragg's law (d) is used to define the average layer spacing (nm) of a porous carbon body relative to the (002) plane. 002 =λ / 2sinθ 002 This was calculated using the formula λ = X-ray wavelength (nm).

[0127] The crystal height (L) defines the crystalline size in a porous carbon body. c , nm) and crystal length (L a The values ​​(nm) were calculated using the following Scherrer formula. crystalline size(nm)=(k·λ) / (β0·cosθ) L a Here, k (shape factor) = 1.84, β0 = full width at half maximum (radian) of the (100) peak in the X-ray diffraction pattern of a porous carbon material, λ = X-ray wavelength (nm), θ = diffraction angle at (100) (Bragg angle, radian). L c Here, k (shape factor) = 0.9, β0 = full width at half maximum (radian) of the (002) peak in the X-ray diffraction pattern of a porous carbon material, λ = X-ray wavelength (nm), θ = diffraction angle of (002) (Bragg angle, radian).

[0128] Using the manufactured porous carbon material, catalysts and half-cells were prepared according to the following conditions, and their electrochemical properties were analyzed.

[0129] Catalyst manufacturing 0.75 g of porous carbon material was dispersed in 388.2 g of a mixture of ethylene glycol (EG) and water (water:EG weight ratio = 1:1) to prepare a dispersion. Then, 4.95 g of a 20 wt% platinum precursor aqueous solution was added to the prepared dispersion to prepare a mixed solution. The prepared mixed solution was heated at 105°C for 1 hour to support the platinum particles on the porous carbon material. After that, the mixed solution was cooled to room temperature, the porous carbon material with the supported platinum particles was filtered, thoroughly washed with distilled water, and dried in a vacuum dryer at a temperature of 250°C to produce a catalyst.

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

[0131] The prepared catalyst was added to distilled water, Nafion (5 wt%), and isopropyl alcohol (IPA), and ultrasonically dispersed to produce a catalyst ink. In the catalyst ink, the catalyst:Nafion mass ratio was 10:3. The catalyst ink prepared using a micropipette was applied to a glassy carbon RDE electrode (5 mm) at a platinum-based concentration of 100 μg / cm³. 2 After loading, the working electrode was prepared by drying at room temperature. Before ORR and CV measurements, it was measured with nitrogen-saturated 0.1M HClO4 electrolyte at 0.05–1.05V. RHEThe catalyst was electrochemically activated at a voltage scanning speed of 100 mV / s within the specified voltage range.

[0132] The circulating voltage-current (CV) method measurement is performed after purging with high-purity nitrogen gas for 30 minutes, then measuring 0.05~1.05V. RHE The voltage scan was performed at a voltage scanning speed of 20 mV / s within the voltage range.

[0133] Electrochemically active surfaces (ECSA) are 0.05-0.4V RHE The calculation was performed using the hydrogen desorption area.

[0134] Oxygen reduction reaction (ORR) measurement is performed by purging high-purity oxygen gas for 30 minutes, followed by measurement at 0.05~1.05V. RHE The test was performed using the linear scanning potential method (LSV) within the specified voltage range, under conditions of an RDE rotation speed of 1600 rpm and a voltage scanning speed of 5 mV / s.

[0135] The catalyst's mass activity (MA) value is 0.9V. RHE The MA values ​​were measured using the linear scanning potential (LSV) method with a 0.1 M HClO4 aqueous solution saturated with high-purity oxygen gas. 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 measured by the electrochemical analyzer, and id is the diffusion-limited current.

[0136] Accelerated stress testing (AST) was performed to test the durability of the catalyst. The AST was conducted using the circulating voltage-current method (CV) at 0.6–1.0V in a 0.1M HClO4 aqueous solution saturated with high-purity nitrogen gas. RHE The test was performed over 10,000 cycles with a voltage scanning speed of 100 mV / s within the specified voltage range. Catalyst durability was compared by comparing the ECSA value and MA@0.9V value before and after AST.

[0137] For comparison with the porous carbon material produced in the examples, the crystallinity and porosity properties of commercial carbon materials were analyzed in the same manner as when analyzing the porous carbon material. Furthermore, catalysts and half-cells were produced using commercial carbon materials, similar to the porous carbon material analysis, and their electrochemical properties were evaluated. The commercial carbon materials 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] Hereafter, when referring to the results measured using each commercial carbon material or the porous carbon material produced in the examples, we simply use the specific trade name of the commercial carbon material or the example number. For example, MH-18 (CNovel TM The electrochemical properties of a half-cell manufactured using TOYO TANSO as a Pt support can be referred to as the electrochemical properties of MH-18. For example, MH-18 (CNovel TM The cumulative delta graph of TOYO TANSO can be referred to as the cumulative delta graph of MH-18. As an example, the porous carbon material produced in Example 1, the catalyst produced using the porous carbon material as a Pt support, and the electrochemical properties of the half-cell can be referred to as the porous carbon material of Example 1, the catalyst of Example 1, and the electrochemical properties of Example 1.

[0139] The specific surface area (SSA1, m) of the porous carbon material produced in the examples and the comparative sample at 2-5 nm. 2 / g), 2~100nm specific surface area (SSA2, m 2 / g)d 002 (nm), L a The (nm) and average number of graphite layers (average number of layers, number of layers) were measured and summarized in Table 2.

[0140] [Table 2]

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

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

[0143] Table 3 summarizes 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 body produced in the examples. Also, the area of ​​the closed curve between P1 and P2 (A) is shown. cl1 ), Area of ​​the closed curve of P2-P3 (A cl2 ) and area ratio (A cl2 / A cl1 The results 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. Cumulative delta graphs of comparative samples are also shown as Figure 5 (cumulative delta graph of the Li-435 sample) and Figure 6 (cumulative delta graph of the MH-18 sample).

[0147] In the examples, all porous carbon bodies produced had cumulative delta graphs located in the positive y-axis region without intersecting the x-axis, as shown in Figure 4. These consisted of four regions: a first decreasing region, a first increasing region, a second decreasing region, and a second increasing region, with one maximum point formed between the first increasing region and the second decreasing region. On the other hand, the comparative samples, similar to Figures 2 and 3, all had cumulative delta graphs that were either simply increasing, intersecting the x-axis (with zero and negative values ​​present), or having two or more maximum points.

[0148] In the porous carbon material produced in the example, the minimum value of the cumulative delta graph in the 2-30 nm range (cm) on the cumulative delta graph. 3 Table 5 summarizes the values ​​( / g, Min), the boundary position between the first increasing region and the second decreasing region (nm, 1-2 boundary), and the boundary position between the second decreasing region and the second increasing region (nm, 2-2 boundary).

[0149] [Table 5]

[0150] The electrochemical properties (electrochemical specific surface area ESCA and mass activity MA) of half-cells equipped with the porous carbon material produced in the example and the carbon material of the comparison sample are summarized in Tables 6 (initial) and 7 (after AST), and the ESCA and MA retention rates after the accelerated stress test are also shown.

[0151] [Table 6]

[0152] [Table 7]

[0153] The above embodiments are merely examples, and the present invention is not limited thereto. Any device having substantially the same configuration and achieving the same effects as the technical concept described in the claims of the present invention is included within the technical scope of the present invention.

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