Carbon material for catalyst carrier of solid polymer fuel cell, catalyst layer for solid polymer fuel cell, and fuel cell

Abstract

A carbon material for a catalyst carrier of a solid polymer fuel cell comprises porous activated carbon black satisfying requirements (A) to (C). (A) The BET specific surface area is 350 m2 / g to 800 m2 / g. (B) The value (VD5-20 / VA20) obtained by dividing the pore volume VD5-20 indicated by pores having a pore diameter of 5-20 nm derived by analysis using a nitrogen desorption isotherm by a Dollimore-Heal (DH) method by the pore volume VA20 indicated by pores having a pore diameter of 20 nm or less derived by analysis using a nitrogen desorption isotherm by the DH method is 0.35 or less. (C) In thermal weight differential thermal analysis, a temperature Td 10% that decreases by 10% when the temperature is raised at 10°C / min in an air atmosphere is 620-680°C.

Description

Carbon material for catalyst support of polymer electrolyte fuel cell, catalyst layer for polymer electrolyte fuel cell, and fuel cell

[0001] The present disclosure relates to a carbon material for a catalyst support of a polymer electrolyte fuel cell, a catalyst layer for a polymer electrolyte fuel cell, and a fuel cell.

[0002] A polymer electrolyte fuel cell, a type of fuel cell, comprises a pair of catalyst layers disposed on both sides of a solid polymer electrolyte membrane, gas diffusion layers disposed on the outer side of each catalyst layer, and separators disposed on the outer side of each gas diffusion layer. One of the pair of catalyst layers serves as the anode of the polymer electrolyte fuel cell, and the other serves as the cathode of the polymer electrolyte fuel cell. In a typical polymer electrolyte fuel cell, multiple unit cells each having the above components are stacked to obtain the desired output.

[0003] A reducing gas such as hydrogen is introduced into the separator on the anode side. The gas diffusion layer on the anode side diffuses the reducing gas, which is then introduced into the anode. The anode contains a catalyst component, a catalyst carrier that supports the catalyst component, and an electrolyte material (ionomer) that has proton conductivity. The catalyst carrier is often made of a carbon material. An oxidation reaction of the reducing gas occurs on the catalyst component, producing protons and electrons. For example, when the reducing gas becomes hydrogen gas, the following oxidation reaction occurs: H ２ →2H ＋ +2e － (E ０ = 0 V)

[0004] Protons produced by this oxidation reaction pass through the electrolyte material in the anode and the solid polymer electrolyte membrane and are introduced into the cathode. Electrons pass through the catalyst support, gas diffusion layer, and separator to be introduced into the external circuit. After performing work (generating electricity) in the external circuit, these electrons are introduced into the cathode-side separator. These electrons then pass through the cathode-side separator and cathode-side gas diffusion layer to be introduced into the cathode.

[0005] The solid polymer electrolyte membrane is made of a proton-conductive electrolyte material and introduces the protons generated in the oxidation reaction to the cathode.

[0006] An oxidizing gas such as oxygen gas or air is introduced into the cathode separator. The cathode gas diffusion layer diffuses the oxidizing gas before introducing it into the cathode. The cathode contains a catalyst component, a catalyst support that supports the catalyst component, and an electrolyte material (ionomer) that has proton conductivity. The catalyst support is often made of a carbon material. A reduction reaction of the oxidizing gas occurs on the catalyst component, producing water. For example, when the oxidizing gas becomes oxygen gas or air, the following reduction reaction occurs: O ２ +4H ＋ +4e － →2H ２ O (E ０ = 1.23 V)

[0007] The water produced by the reduction reaction is discharged outside the fuel cell along with the unreacted oxidizing gas. In this way, solid polymer fuel cells generate electricity by utilizing the energy difference (potential difference) between the oxidation reaction and the reduction reaction. In other words, the electrons produced by the oxidation reaction perform work in the external circuit.

[0008] Incidentally, from the viewpoint of power generation performance of fuel cells, it has been proposed to use porous carbon black as a catalyst support. Non-Patent Document 1 reports that the catalytic metal supported in the pores formed inside the porous carbon black is highly active because it is not subject to reaction inhibition (poisoning) caused by the coexisting ionomer coating. Patent Document 1 reports that the average particle diameter is 20 to 100 nm, and the pore volume of the porous carbon black with a pore diameter of 4 to 20 nm is 0.23 to 0.78 cm ３ / g porous carbon black has been proposed. Patent Document 2 proposes a method of contacting a carbon black starting material with an oxidizing agent in a fluidized bed as a method of making carbon black porous and increasing the surface area. Specifically, Patent Document 2 describes a "method for producing high surface area graphitized carbon, in which the surface area of ​​the carbon black starting material is at least 100 m2 greater than the surface area of ​​the starting carbon material. ２In the preceding article, a "method of producing a high surface area graphitized carbon having a surface area of ​​at least 1.32 cc / g, the method comprising the steps of oxidizing and graphitizing the starting carbon material, the oxidation occurring before the graphitization, the oxidation producing the high surface area carbon, and the high surface area graphitized carbon having an average pore volume of at least 1.32 cc / g."

[0009] In addition, from the viewpoint of durability of fuel cells, it has been proposed to bake porous carbon black to make it highly crystallized. ２ 1 / g and a crystallite size Lc of 2.0 nm or more. In Patent Document 4, a highly crystalline carbon black having a BET specific surface area of ​​2.0 nm or more and a G-band (1590 cm) in the spectrum of the carbon surface by Raman spectroscopy is proposed. －１ ) peak area relative to the D1-band (1350 cm －１ ) the peak area ratio D / G is 0.5 to 2.5, the pores include mesopores, and the mesopore volume is 0.35 to 1.3 cm ３ / g porous carbon has been proposed.

[0010] Furthermore, techniques for obtaining porous carbon black by activating raw carbon black have also been proposed. Patent Document 5 proposes a method for making carbon black porous by heat-treating it and then activating it with air. Patent Document 6 proposes a method for making carbon black porous by activating it with CO after supporting a catalytic metal. ２ Patent Document 7 proposes a method of controlling the coating site of an ionomer by air-activating carbon black and changing the pore volume of 5 nm to 40 nm.

[0011] Patent Document 1: JP 2013-109856 A Patent Document 2: JP 5650542 A Patent Document 3: JP 6478677 A Patent Document 4: WO 17 / 208742 Patent Document 5: JP 6563945 A Patent Document 6: JP 5326585 A Patent Document 7: JP 6772952 A

[0012] Kongkanand et al., ACS Energy Lett. 2018, 3, 618-621

[0013] In solid polymer fuel cells, porous carbon black as a carbon material for a catalyst carrier is required to have not only durability but also low-load characteristics (characteristics when generating electricity at a low current) as power generation performance. However, in the prior art, including the above-mentioned documents, porous carbon black has not yet been able to sufficiently achieve both high durability and low-load characteristics.

[0014] For example, in Patent Document 5, an activation treatment is carried out after heat treatment. However, since the heat-treated, highly crystalline carbon wall is activated, the activation effect is low and the improvement in pore volume is insufficient. In addition, since air is used as the activation gas, a combustion reaction occurs on the carbon black surface, resulting in the formation of pores with large diameters, which makes it easy for the ionomer to penetrate into the particle interior. As a result, the improvement in low-load characteristics is insufficient.

[0015] In addition, in Patent Document 6, the supported catalytic metal also acts as an activation catalyst, so that the catalyst support site is selectively activated. As a result, the catalyst particles are present on the carbon surface, which is not sufficient to prevent the catalyst from being poisoned by the ionomer.

[0016] Furthermore, Patent Document 7 describes that the ionomer coating site is controlled by changing the volume of pores of 5 nm to 40 nm. However, the pore volume obtained by analyzing the nitrogen adsorption / desorption isotherm on the adsorption side is not sufficient to express the state of communication between the inside and outside of the particle, and is not optimal as an indicator of whether or not the ionomer can penetrate.

[0017] In Patent Document 2, a carbon black starting material having a first BET nitrogen surface area is contacted with an oxidant in a fluidized bed under conditions effective to produce a carbon black product having a second BET nitrogen surface area greater than the first BET nitrogen surface area, thereby reacting the oxidant with the carbon black in the fluidized bed to make it porous. However, when carbon black having a particle size distribution is used in a fluidized bed, a distribution occurs in the fluidized state, resulting in a distribution in the degree of activation.

[0018] Therefore, an object of the present disclosure is to provide a carbon material for a catalyst support of a polymer electrolyte fuel cell that combines high durability and low load characteristics, a catalyst layer for a polymer electrolyte fuel cell that uses the same, and a fuel cell.

[0019] The means for solving the problems include the following aspects: <1> A carbon material for a catalyst support of a polymer electrolyte fuel cell, comprising a porous activated carbon black that satisfies the following requirements (A), (B), and (C): (A) a BET specific surface area of ​​350 m ２ / g or more 800m ２ (B) The pore volume VD of pores having a pore diameter of 5 nm or more and 20 nm or less, which is determined by analyzing a nitrogen desorption isotherm using the DH (Dollimore-Heal) method, is ５－２０ The pore volume VA of pores with a pore diameter of 20 nm or less, which is obtained by analyzing the nitrogen adsorption isotherm using the DH (Dollimore-Heal) method, ２０ The value divided by (VD ５－２０ / VA ２０ (C) In thermogravimetric differential thermal analysis (TG-DTA), the temperature Td at which the weight decreases by 10% when the temperature is increased at 10°C / min in an air atmosphere is 0.35 or less. １０％ <2> The pore volume VA ２０ <1> The carbon material for a catalyst support of a polymer electrolyte fuel cell according to <1>, wherein the specific surface area is 0.36 to 0.90 mL / g. <3> A catalyst layer for a polymer electrolyte fuel cell, comprising the carbon material for a catalyst support of a polymer electrolyte fuel cell according to <1> or <2>. <4> A fuel cell, comprising the catalyst layer for a polymer electrolyte fuel cell according to <3>. <5> The fuel cell according to <4>, wherein the catalyst layer for a polymer electrolyte fuel cell is a catalyst layer on the cathode side.

[0020] According to the present disclosure, there are provided a carbon material for a catalyst support of a polymer electrolyte fuel cell that combines high durability and low load characteristics, a catalyst layer for a polymer electrolyte fuel cell that uses the same, and a fuel cell.

[0021] FIG. 1 is a schematic diagram showing an example of the general configuration of a fuel cell according to the present disclosure.

[0022] In this disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. Furthermore, when "greater than" or "less than" is added to the numerical values ​​written before and after "to", the numerical range means a range that does not include these numerical values ​​as the lower or upper limit. In this disclosure, the term "process" does not only refer to an independent process, but also includes processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In this disclosure, the "electrolyte material having proton conductivity" used in the catalyst layer of a fuel cell is also referred to as an "ionomer."

[0023] <Carbon material for catalyst support of polymer electrolyte fuel cell> The carbon material for catalyst support of polymer electrolyte fuel cell of the present disclosure is made of porous activated carbon black that satisfies the requirements (A), (B), and (C) described below. Here, porous activated carbon black is carbon black that has been made porous by activation. Note that porous activated carbon black is also referred to as "porous carbon black."

[0024] The carbon material for a catalyst support according to the present disclosure is a carbon material that combines high durability and low load characteristics. The carbon material according to the present disclosure was discovered based on the following findings.

[0025] In recent years, with the growing interest in carbon neutrality, ２ There is a growing demand for fuel cells in the field of large-scale commercial mobility vehicles (hereinafter referred to as "HDVs"), which have high emissions. HDVs require higher durability than passenger cars, so catalyst carriers must be more durable during power generation. At the same time, materials must be inexpensive for HDVs, which are primarily used for commercial vehicles.

[0026] It has been found that when porous carbon materials with internal mesopores, such as dendritic carbon materials obtained by the autolysis reaction of silver acetylide, Ketjen Black, and Knobel, are used as carbon materials for catalyst supports, the catalyst supported in the internal mesopores is protected from poisoning by ionomers, resulting in improved activity and low-load characteristics. However, since these porous carbon materials are expensive, it is effective to use porous carbon black, which is made porous by activating carbon black, an inexpensive raw material, to reduce costs. However, at present, porous carbon black does not yet sufficiently combine high durability with low-load characteristics.

[0027] The inventors have therefore investigated the properties of porous carbon black that enable it to simultaneously achieve high durability and low-load characteristics, and have discovered the following: (1) It is important to "control activation" so that the "specific surface area," "adsorption volume up to 20 nm," and "desorption pore volume of 5 to 20 nm" are all within their respective preferred ranges. (2) Controlling activation is effective when the degree of activation is highly uniform (specifically, for example, activation by reversing the flow direction of the activation gas flowing through the raw carbon black). (3) Activation that results in a highly uniform degree of activation can increase the average pore volume without producing porous carbon black that is overly activated and has widened pores connecting the interior and exterior. (4) As a result, the porous carbon black has sufficient space within it for supporting the catalytic metal, and the pores connecting the interior and exterior are narrow, preventing poisoning of the catalytic metal by the ionomer, thereby suppressing a decrease in catalytic activity and a decrease in low-load characteristics. (5) Regarding durability, it is important to "control the heat treatment" so that the "10% weight loss temperature measured by TG-DTA" falls within an appropriate range.

[0028] From the above findings, it has been found that the carbon material for a catalyst support according to the present disclosure is a carbon material that combines high durability and low load characteristics.

[0029] Requirements (A), (B), and (C) will be explained below.

[0030] (Requirement (A)) (A) BET specific surface area is 350 m ２ / g or more 800m ２ / g or less. The BET specific surface area of ​​the porous carbon black is 350 m ２ / g or more 800m ２ / g or less, the catalytic metal to be supported can be supported with good dispersibility at a target loading rate and particle size within a practical range, and the porous carbon black can have a crystallite structure necessary for obtaining the durability required for fuel cells. ２ If the BET specific surface area of ​​the porous carbon black is less than 800 m / g, the particle size of the catalyst metal increases when the catalyst metal loading rate is increased, or the catalyst metal particles aggregate, making it difficult to obtain high battery performance. ２ If the BET specific surface area of ​​the porous carbon black is more than 350 m / g, high power generation performance can be obtained, but the porous carbon black tends to have a crystallite structure necessary for maintaining durability, making it difficult to achieve both high durability and low load characteristics. ２ / g or more 600m ２ / g or less.

[0031] The BET specific surface area is a value measured by the method described in the Examples section below.

[0032] (Requirement (B)) (B) The pore volume VD of pores having a pore diameter of 5 nm or more and 20 nm or less, which is obtained by analyzing a nitrogen desorption isotherm using the DH (Dollimore-Heal) method. ５－２０ The pore volume VA of pores with a pore diameter of 20 nm or less, which is obtained by analyzing the nitrogen adsorption isotherm using the DH (Dollimore-Heal) method, ２０ The value divided by (VD ５－２０ / VA ２０ ) is 0.35 or less.

[0033] The value of porous carbon black (VD ５－２０ / VA ２０ ) indicates the degree of uniformity of the activation of the porous carbon black. ５－２０ / VA ２０If the ratio (ratio) exceeds 0.35, the degree of activation will be poor and the number of porous carbon blacks with an excessive number of pores connecting the interior and exterior of the porous carbon black will increase, causing the ionomer to penetrate into the interior of the porous carbon black and deteriorating the low load characteristics.

[0034] In other words, the BET specific surface area is 350 m ２ / g or more 800m ２ / g or less, and the value of porous carbon black (VD ５－２０ / VA ２０ When the ionomer ratio is 0.35 or less, the porous carbon black has sufficient space inside to support the catalytic metal, and the pores connecting the inside and outside are narrow. This prevents the catalytic metal from being poisoned by the ionomer, thereby suppressing a decrease in catalytic activity. As a result, a decrease in low-load characteristics is suppressed.

[0035] The value of porous carbon black (VD ５－２０ / VA ２０ On the other hand, from the viewpoint of supplying oxygen gas to the internal mesopores and discharging the generated water, the value of the porous carbon black (VD ５－２０ / VA ２０ The lower limit of ) is, for example, 0.10 or more.

[0036] Here, the pore volume VD of the porous carbon black ５－２０ represents the amount of pores connecting the inside and outside of the porous carbon black, and indicates the ease with which the ionomer penetrates into the inside of the porous carbon black. ５－２０ The pore volume VD of the porous carbon black is preferably 0.4 mL / g or less, and more preferably 0.3 mL / g or less. ５－２０ When the pore volume VD of the porous carbon black is 0.4 mL / g or less, the uniformity of the activation degree is improved, and the number of pores connecting the inside and outside of the porous carbon black is prevented from becoming excessively large. As a result, the ionomer is less likely to penetrate into the inside of the porous carbon black, and the low load characteristics are improved. However, from the viewpoints of supplying oxygen gas to the mesopores in the porous carbon black and discharging the generated water, the pore volume VD of the porous carbon black is ５－２０The lower limit is, for example, 0.05 mL / g or more.

[0037] On the other hand, the pore volume VA of the porous carbon black ２０ represents the pore volume inside the porous carbon black. Pore volume VA of porous carbon black ２０ The pore volume VA of the porous carbon black is preferably 0.36 to 0.90 mL / g, and more preferably 0.39 to 0.61 mL / g. ２０ When the pore volume VA of the porous carbon black is 0.36 mL / g or more, the internal volume of the porous carbon black is sufficiently secured, and the amount of the catalytic metal supported inside the porous carbon black increases. As a result, the catalytic metal is less likely to be poisoned by the ionomer, and the low-load characteristics are improved. ２０ When the pore volume of the porous carbon black is 0.9 mL / g or less, the pore volume inside the porous carbon black is large, and the uniformity of the activation degree is ensured, while the porous carbon black has sufficient strength to suppress collapse, thereby improving durability.

[0038] The pore volume VD ５－２０ , and pore volume VA ２０ is a value measured by the method described in the Examples below.

[0039] (Requirement (C)) (C) In thermogravimetric differential thermal analysis (TG-DTA), the temperature Td at which the weight decreases by 10% when the temperature is increased at 10°C / min in an air atmosphere １０％ The 10% weight loss temperature (Td) of porous carbon black is 620 to 680°C. １０％ If the temperature is less than 620°C, the porous carbon black will be subject to high oxidation wear and will not be able to ensure sufficient durability. １０％ If the temperature exceeds 680°C, the surface area of ​​the porous carbon black decreases, and the low load characteristics deteriorate. １０％ is preferably 640 to 680°C.

[0040] The 10% weight loss temperature Td １０％ is a value measured by the method described in the Examples below.

[0041] <Method for producing carbon material for catalyst support of polymer electrolyte fuel cell> Hereinafter, an example of a method for producing a carbon material for catalyst support of a polymer electrolyte fuel cell according to the present disclosure (hereinafter also referred to as a "method for producing a carbon material") will be described.

[0042] The method for producing a carbon material according to the present disclosure is a method for activating raw carbon black by treating the raw carbon black in the order of a "first activation step," a "heat treatment step," and a "second activation step," and reversing the flow direction of the activation gas flowing through the raw carbon black in the "first activation step." The method for producing a carbon material according to the present disclosure provides a carbon material (i.e., porous activated carbon black) that satisfies requirements (A) to (C).

[0043] (First Activation Step) In the first activation step, the flow direction of the activation gas flowing through the raw carbon black is reversed to activate it. The reversal of the flow direction of the activation gas may be performed once or may be repeated two or more times. By reversing the flow direction of the activation gas, it is possible to suppress the difference in activation degree that occurs between the raw carbon black on the upstream side of the activation gas flow path and the raw carbon black on the downstream side of the activation gas flow path. In other words, it is possible to increase the uniformity of the activation degree of the porous carbon black.

[0044] Examples of raw carbon black include furnace black, which is produced by continuously pyrolyzing a gaseous or liquid raw material in a reactor; channel black, which is produced by burning a raw material gas and applying the flame to the bottom surface of a channel steel to rapidly cool and precipitate the carbon black; thermal black, which is produced by periodically repeating combustion and pyrolysis of a gas as the raw material; and acetylene black, which is produced from acetylene gas as the raw material. Furnace black is preferred as the raw carbon black from the viewpoints of ease of generating internal pores upon activation and a primary particle size suitable for use as a catalyst support for solid polymer fuel cells. These carbon blacks can be used alone or in combination of two or more types, but from the viewpoint of uniform activation, it is preferable to use them alone.

[0045] (Heat Treatment Step) In the heat treatment step performed after the first activation step, heat treatment is performed in an inert atmosphere to grow the crystallites constituting the raw material carbon black that has undergone the first activation step, thereby imparting the durability required for fuel cells. By performing the heat treatment step, the 10% weight loss temperature Td of the porous carbon black is reached. １０％ This keeps the temperature high, improving oxidation resistance (i.e., durability).

[0046] In the heat treatment step, the raw carbon black that has undergone the first activation step is heat-treated in a vacuum or in an inert gas (nitrogen, argon, etc.) atmosphere at a temperature of 1500°C to 1900°C (preferably 1600 to 1800°C). Heat treatment at 1500°C or higher develops highly aromatic carbon crystals that form the skeleton of the porous carbon black, and the pore walls become sufficiently thick, resulting in porous carbon black that satisfies requirement (C). Heat treatment at 1900°C or lower suppresses a decrease in the pore volume of mesopores due to excessive crystallization of carbon.

[0047] (Second Activation Step) In the second activation step, activation is performed to reopen the pores of the heat-treated activated carbon black intermediate that were closed in the heat treatment step. This increases the specific surface area and pore volume that were reduced in the heat treatment step. Without the second activation step, it is difficult to obtain a sufficient specific surface area and pore volume. Note that, in the second activation step, it is also preferable to reverse the flow direction of the activation gas flowing through the raw carbon black to perform activation.

[0048] Then, by undergoing the first activation step and the second activation step, porous carbon black is obtained which has sufficient space inside the porous carbon black for supporting the catalytic metal and has narrow pores connecting the inside and outside, thereby satisfying requirements (A) and (B).

[0049] (Activation Modes of the First Activation Step and the Second Activation Step) The type of activation gas used in the first activation step and the second activation step is not particularly limited as long as it contains a gas capable of oxidizing and consuming the carbon constituting the raw carbon black through a reaction. Examples of gases capable of oxidizing and consuming the carbon constituting the raw carbon black through a reaction include air, oxygen, ozone, water vapor, carbon dioxide, nitrogen dioxide, nitric oxide, and nitrous oxide. The activation gas may be a mixture of these gases. Alternatively, the activation gas may be a gas diluted with an inert gas such as nitrogen, argon, or helium. Furthermore, exhaust gases or industrial gases containing these gases may also be used. Preferably, the activation gas is water vapor or carbon dioxide, or a gas containing these. The type of gas used in the first activation step and the second activation step may be different.

[0050] As the activation device for the first activation step and the second activation step, various types of devices such as a rotary kiln, a fluidized bed furnace, a fixed bed furnace, a moving bed furnace, etc. can be used, and either a continuous furnace in which raw materials are continuously charged and the product is discharged, or a batch furnace in which they are conducted intermittently, can be used. As the activation device, a rotary kiln and a fixed bed furnace are preferred because they allow easy switching of the gas introduction direction. Furthermore, from the viewpoint of uniformity of the activation degree, a batch furnace is preferred because a continuous furnace in which raw materials are continuously charged causes a distribution in the activation degree.

[0051] In an activation apparatus for activating raw carbon black in the first activation step and the second activation step (particularly the first activation step), it is preferable to change the direction of activation gas introduction. Changing the gas introduction direction can be achieved by swapping the gas inlet and outlet, or by reversing the direction of the furnace tube when a tubular furnace or similar is used as the activation apparatus. The proportion of gas flowing from the initial gas introduction direction at the end of activation can be expressed as GasR ([supply amount from the initial gas introduction direction] / (supply amount from the initial gas introduction direction + supply amount from the reversed gas introduction direction)) × 100. A GasR value of 30 to 70% is preferred. If the GasR value is 70% or higher, the raw carbon black on the initial gas introduction side will be excessively activated, resulting in a loss of uniformity in activation. On the other hand, if the GasR value is 30% or lower, the raw carbon black on the initial gas discharge side will be excessively activated, resulting in a loss of uniformity in activation.

[0052] <Catalyst Layer for Polymer Electrolyte Fuel Cell and Polymer Electrolyte Fuel Cell> A catalyst layer for a polymer electrolyte fuel cell according to the present disclosure will now be described, along with a polymer electrolyte fuel cell. The carbon material according to the present disclosure can be applied to, for example, catalyst layers 150 and 160 provided in a polymer electrolyte fuel cell 100 shown in FIG. 1. FIG. 1 is a schematic diagram showing an example of the overall configuration of a fuel cell according to the present disclosure. The polymer electrolyte fuel cell 100 shown in FIG. 1 includes separators 110 and 120, gas diffusion layers 130 and 140, catalyst layers 150 and 160, and an electrolyte membrane 170.

[0053] The separator 110 is an anode-side separator that introduces a reducing gas such as hydrogen into the gas diffusion layer 130. The separator 120 is a cathode-side separator that introduces an oxidizing gas such as oxygen gas or air into the gas diffusion condensation phase. The types of the separators 110 and 120 are not particularly limited, and may be any separator used in conventional fuel cells (e.g., solid polymer fuel cells).

[0054] The gas diffusion layer 130 is an anode-side gas diffusion layer that diffuses the reducing gas supplied from the separator 110 and then supplies the gas to the catalyst layer 150. The gas diffusion layer 140 is a cathode-side gas diffusion layer that diffuses the oxidizing gas supplied from the separator 120 and then supplies the gas to the catalyst layer 160. The type of gas diffusion layers 130 and 140 is not particularly limited, and they may be any gas diffusion layer used in conventional fuel cells (e.g., polymer electrolyte fuel cells). Examples of the gas diffusion layers 130 and 140 include porous carbon materials (carbon cloth, carbon paper, etc.) and porous metal materials (metal mesh, metal wool, etc.). A preferred example of the gas diffusion layers 130 and 140 is a gas diffusion layer with a two-layer structure. Specifically, the gas diffusion layers 130 and 140 have a two-layer structure in which the layer on the separator 110 or 120 side is a gas diffusion fiber layer mainly composed of a fibrous carbon material, and the layer on the catalyst layer 150 or 160 side is a micropore layer mainly composed of carbon black.

[0055] The catalyst layer 150 is a so-called anode. In the catalyst layer 150, an oxidation reaction of the reducing gas occurs, producing protons and electrons. For example, when the reducing gas becomes hydrogen gas, the following oxidation reaction occurs: H ２ →2H ＋ +2e － (E ０ = 0 V)

[0056] Protons produced by the oxidation reaction pass through the catalyst layer 150 and electrolyte membrane 170 to reach the catalyst layer 160. Electrons produced by the oxidation reaction pass through the catalyst layer 150, gas diffusion layer 130, and separator 110 to reach the external circuit. The electrons perform work (generate electricity) in the external circuit and then enter the separator 120. The electrons then pass through the separator 120 and gas diffusion layer 140 to reach the catalyst layer 160.

[0057] There are no particular limitations on the configuration of the catalyst layer 150 that serves as the anode. The configuration of the catalyst layer 150 may be the same as that of a conventional anode, the same as that of the catalyst layer 160, or a configuration that is more hydrophilic than the catalyst layer 160.

[0058] The catalyst layer 160 is a so-called cathode. Within the catalyst layer 160, a reduction reaction of the oxidizing gas occurs, producing water. For example, when the oxidizing gas becomes oxygen gas or air, the following reduction reaction occurs. The water produced by the oxidation reaction is discharged to the outside of the polymer electrolyte fuel cell 100 together with the unreacted oxidizing gas. ２ +4H ＋ +4e － →2H ２ O (E ０ = 1.23 V)

[0059] In this way, the energy difference (potential difference) between the oxidation reaction and the reduction reaction is utilized to generate electricity in the polymer electrolyte fuel cell 100. In other words, the electrons generated in the oxidation reaction perform work in an external circuit.

[0060] The catalyst layer 160 contains the carbon material for a catalyst support of the present disclosure. That is, the catalyst layer 160 contains the carbon material for a catalyst support of the present disclosure, an electrolyte material (ionomer), and a catalyst component (platinum, etc.). This can improve the durability and low-load characteristics within the catalyst layer 160. This can also improve the durability and low-load characteristics of the solid polymer electrolyte fuel cell 100.

[0061] The catalyst loading rate in the catalyst layer 160 is not particularly limited, but is preferably 30% by mass or more and less than 80% by mass. A catalyst loading rate within this range further enhances durability and low-load characteristics. Here, the catalyst loading rate is expressed as the mass percentage of the catalyst component relative to the total mass of the catalyst-loaded particles (particles in which the catalyst component is loaded on a carbon material for catalyst support). If the catalyst loading rate is less than 30% by mass, it may be necessary to thicken the catalyst layer 160 to ensure that the polymer electrolyte fuel cell 100 is practically usable. On the other hand, if the catalyst loading rate is 80% by mass or more, catalyst aggregation is likely to occur. Furthermore, if the catalyst layer 160 becomes too thin, flooding may occur.

[0062] The mass ratio I / C of the mass I of the electrolyte material in the catalyst layer 160 to the mass C of the catalyst support carbon material is not particularly limited, but is preferably greater than 0.5 and less than 5.0. In this case, both the pore network and the electrolyte material network can be achieved, resulting in improved durability and low-load characteristics. On the other hand, if the mass ratio I / C is 0.5 or less, the electrolyte material network tends to be weak and the proton conduction resistance tends to be high. If the mass ratio I / C is 5.0 or more, the pore network may be disrupted by the electrolyte material. In either case, durability and low-load characteristics may be reduced.

[0063] Furthermore, the thickness of the catalyst layer 160 is not particularly limited, and is preferably more than 5 μm and less than 20 μm. In this case, the oxidizing gas is more likely to diffuse within the catalyst layer 160, and flooding is less likely to occur. If the thickness of the catalyst layer 160 is 5 μm or less, flooding is more likely to occur. If the thickness of the catalyst layer 160 is 20 μm or more, the oxidizing gas is less likely to diffuse within the catalyst layer 160, and the catalytic components near the electrolyte membrane 170 become less effective. In other words, there is a possibility that the catalyst utilization rate will decrease.

[0064] The electrolyte membrane 170 is composed of a proton-conducting electrolyte material. The electrolyte membrane 170 introduces protons generated in the oxidation reaction to the catalyst layer 160 (cathode). The type of electrolyte material is not particularly limited, and any electrolyte material used in conventional fuel cells, such as solid polymer fuel cells, may be used. An example of a suitable electrolyte material is an electrolyte resin. Examples of electrolyte resins include polymers with phosphate groups, sulfonic acid groups, etc. Specific examples include perfluorosulfonic acid polymers and polymers with benzenesulfonic acid, etc. Of course, other types of electrolyte materials may also be used. Examples of such electrolyte materials include inorganic and inorganic-organic hybrid electrolyte materials. The solid polymer fuel cell 100 may be a fuel cell that operates within a temperature range from room temperature (25°C) to 150°C.

[0065] <Method for manufacturing a polymer electrolyte fuel cell> The method for manufacturing the polymer electrolyte fuel cell 100 is not particularly limited, and may be the same as a conventional manufacturing method. However, the catalyst carrier uses the carbon material for a catalyst carrier of the present disclosure. Of the catalyst layers 150 and 160, it is preferable to use the carbon material for a catalyst carrier of the present disclosure for the catalyst carrier of at least the catalyst layer 160 that serves as the cathode. Of course, the carbon material for a catalyst carrier of the present disclosure may also be used for the catalyst carrier of both the catalyst layer 150 that serves as the anode and the catalyst layer 160 that serves as the cathode.

[0066] Experimental examples of the carbon material for a catalyst support according to the present disclosure will be described below. First, the method for measuring each parameter will be described.

[0067] <Method of measuring each parameter> (Nitrogen adsorption / desorption isotherm (VA ２０ , V.D. ５－２０ Measurement of BET specific surface area) Approximately 30 mg of a sample of the carbon material for catalyst support was weighed out and vacuum dried at 200°C for 2 hours, and then nitrogen adsorption / desorption isotherms were measured using an automatic specific surface area measuring device (AUTOSORB iQ manufactured by Anton Paar Japan) with nitrogen gas as the adsorbate. ２０ , and the pore volume VD of pores with a diameter of 5 to 20 nm ５－２０ The BET specific surface area was calculated by analyzing the nitrogen adsorption / desorption isotherm using the DH method with the software attached to the device. ０ was calculated by BET analysis of the nitrogen adsorption isotherm in the range of 0.30 or less.

[0068] (10% weight loss temperature Td in thermogravimetric differential thermal analysis (TG-DTA) １０％ Measurement of weight loss (Td)) Approximately 6 mg of a carbon material for a catalyst carrier was weighed out as a sample. The sample was then set in a thermogravimetric and differential calorimeter (Hitachi High-Technologies Corporation, EXSTAR TG / DTA7200) and measured for weight loss up to 900°C at a heating rate of 10°C / min and in a dry air flow of 200 mL / min. The weight at the start of the obtained weight loss curve was set to 100%, and the weight at the end of the measurement was set to 0%, and the temperature at the time of 10% weight loss was determined as the 10% weight loss temperature Td. １０％ It was decided.

[0069] <Example: Preparation of carbon material for catalyst support> (Example 1) (1) First activation step A tubular reactor having a diameter of 1 inch was filled with 7 g of Niteron #10 manufactured by Nippon Steel Carbon as a raw material and carbon black, and a CO flow rate of 400 Nml / min was applied using a mass flow controller installed upstream of the tubular reactor. ２ In this state, the tubular reactor was heated to 840°C at a rate of 20°C / min. and maintained at 840°C for 36 hours. Then, the valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor, and the reactor was maintained at 840°C for another 36 hours, thereby carrying out the first activation step. After the maintenance, the flow gas was changed to N ２ The temperature was lowered, and the first activated sample was collected.

[0070] (2) Heat Treatment Step The entire amount of the recovered first activation sample was placed in a heating crucible, and the temperature was increased at 15°C / min in a heating furnace under Ar flow, and a heat treatment step was performed at 1600°C for 1 hour, and a heat-treated sample was recovered.

[0071] (3) Second activation step The entire heat-treated sample was again loaded into a tubular reactor with a diameter of 1 inch, and CO was introduced at 400 Nml / min. using a mass flow controller set up upstream of the tubular reactor. ２ In this state, the tubular reactor was heated to 850°C at a rate of 20°C / min and maintained at 850°C for 15 minutes. Thereafter, the valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor, and the reactor was maintained at 850°C for another 15 minutes to perform a second activation. After the maintenance, the flow gas was changed to N ２ The second activated sample obtained by these operations was recovered as the carbon material for a catalyst support of Example 1 (i.e., porous activated carbon black).

[0072] Example 2 A carbon material for a catalyst support (that is, porous activated carbon black) was obtained in the same manner as in Example 1, except that the holding temperature in the heat treatment step was 1800°C.

[0073] Example 3 A carbon material for a catalyst support (i.e., porous activated carbon black) was obtained in the same manner as in Example 1, except that in the first activation step, the tubular reactor was heated and then held at 840°C for 24 hours, and then the valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor, and the reactor was further held at 840°C for 48 hours.

[0074] Example 4 A carbon material for a catalyst support (i.e., porous activated carbon black) was obtained in the same manner as in Example 1, except that in the first activation step, the temperature of the tubular reactor was increased to 820°C at a rate of 20°C / min, and then the temperature was maintained at 820°C for 36 hours. Thereafter, the valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor, and the temperature was maintained at 820°C for another 36 hours.

[0075] Example 5 A carbon material for a catalyst support (i.e., porous activated carbon black) was obtained in the same manner as in Example 1, except that in the first activation step, the tubular reactor was heated to 820°C at a rate of 20°C / min, and held at 820°C for 36 hours, and then valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor, and the reactor was further held at 820°C for 36 hours, and the holding time in the second activation step was set to 2 hours (1 hour each before and after reversing the gas direction, totaling 2 hours).

[0076] Example 6 A carbon material for a catalyst carrier (i.e., porous activated carbon black) was obtained in the same manner as in Example 1, except that in the first activation step, Niteron #3350 manufactured by Nippon Steel Carbon was used as the raw material carbon black, the temperature of the tubular reactor was raised to 1000°C at a rate of 20°C / min and held at 1000°C for 3 hours, and then valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor and the temperature was held at 1000°C for an additional 3 hours, the holding temperature in the heat treatment step was changed to 1700°C, and the holding time in the second activation step was changed to 950°C and 4 hours (2 hours each before and after reversing the gas direction, for a total of 4 hours).

[0077] Example 7 A carbon material for a catalyst support (i.e., porous activated carbon black) was obtained in the same manner as in Example 1, except that in the first activation step, Niteron #3350 manufactured by Nippon Steel Carbon was used as the raw material carbon black, the temperature of the tubular reactor was raised to 1000°C at a rate of 20°C / min and held at 1000°C for 3 hours, and then valves installed upstream and downstream of the tubular reactor were operated to reverse the direction of the gas introduced into the tubular reactor and the temperature was held at 1000°C for an additional 3 hours, the holding temperature in the heat treatment step was changed to 1700°C, and the holding time in the second activation step was changed to 950°C and 2 hours (1 hour each before and after reversing the gas direction, for a total of 2 hours).

[0078] (Example 8) In the first activation step, 230 g of Nitelon #10 manufactured by Nippon Steel Carbon Co., Ltd. was filled to a uniform thickness into a cylindrical retort container with an inner diameter of 120 mm and a length of 500 mm and equipped with four lifters. The retort container was placed inside a rotary kiln and CO was introduced at a flow rate of 3000 Nml / min. ２ The rotary kiln was rotated at a speed of one rotation per second while the gas was circulated. In this state, the rotary kiln was heated to 850°C at a rate of 20°C / min. and maintained at 850°C for 35 hours. After the temperature was maintained at 850°C, the gas was changed to N ２ The temperature was lowered by switching to 0.5°C, the retort container was removed from the rotary kiln, turned upside down, and then reinstalled in the rotary kiln. ２ The gas was passed through the rotary kiln and rotated at a speed of one rotation per second. In this state, the rotary kiln was heated to 850°C at a rate of 20°C / min. and then maintained at 850°C for 35 hours. After the temperature was maintained, the gas was changed to N ２ The temperature was then switched to 950°C, the temperature was lowered, and the first activation sample was recovered. The holding temperature in the second activation step was 950°C, and the holding time was 0.5 hours (15 minutes each before and after reversing the gas direction, for a total of 0.5 hours). Except for these operations, the same procedure as in Example 1 was carried out.

[0079] Comparative Example 1 A carbon material for a catalyst support was obtained in the same manner as in Example 1, except that the direction of the gas introduced into the tubular reactor was not reversed in the first activation step.

[0080] Comparative Example 2 A carbon material for a catalyst support was obtained in the same manner as in Example 8, except that in the first activation step, the retort container was not taken out from the rotary kiln and turned upside down.

[0081] Comparative Example 3 A carbon material for a catalyst support was obtained in the same manner as in Example 8, except that in the first activation step, the holding time before inverting the retort container was 56 hours and the holding time after inverting the retort container was 14 hours.

[0082] Comparative Example 4 A carbon material for a catalyst support was obtained in the same manner as in Example 8, except that in the first activation step, the holding time before inverting the retort container was 14 hours and the holding time after inverting the retort container was 56 hours.

[0083] Comparative Example 5 A carbon material for a catalyst support was obtained in the same manner as in Example 1, except that the second activation step was not carried out.

[0084] Comparative Example 6 A carbon material for a catalyst support was obtained in the same manner as in Example 1, except that the holding temperature in the heat treatment step was set to 1400°C.

[0085] Comparative Example 7 A carbon material for a catalyst support was obtained in the same manner as in Example 1, except that the holding temperature in the heat treatment step was 1200°C.

[0086] Comparative Example 8 A carbon material for a catalyst support was obtained in the same manner as in Example 1, except that the holding temperature in the heat treatment step was set to 2000°C.

[0087] Comparative Example 9 Ketjen Black EC300J manufactured by Lion Specialty Chemicals Co., Ltd., which was not subjected to any additional treatment, was used as the carbon material for a catalyst support in Comparative Example 9.

[0088] Comparative Example 10 Ketjen Black EC600JD manufactured by Lion Specialty Chemicals Co., Ltd., which was not subjected to any additional treatment, was used as the carbon material for a catalyst support in Comparative Example 10.

[0089] Comparative Example 11 A carbon material for a catalyst support of Comparative Example 11 was obtained by subjecting 2 g of Ketjen Black EC300J (manufactured by Lion Specialty Chemicals Co., Ltd.) as raw material carbon black to a heat treatment furnace at 1600°C for 1 hour under Ar flow.

[0090] Comparative Example 12 A carbon material for a catalyst support of Comparative Example 12 was obtained by subjecting 2 g of Ketjen Black EC600JD (manufactured by Lion Specialty Chemicals Co., Ltd.) as raw material carbon black to a heat treatment furnace under a flow of Ar at 1600°C for 1 hour.

[0091] <Preparation of catalyst, preparation of catalyst layer, fabrication of MEA, assembly of fuel cell, and evaluation of cell performance (power generation performance, durability)> Next, using each of the porous carbon blacks prepared as described above, a catalyst for a polymer electrolyte fuel cell carrying a catalyst metal was prepared as follows. A catalyst layer ink liquid was prepared using the obtained catalyst, and then a catalyst layer was formed using this catalyst layer ink liquid. Furthermore, a membrane electrode assembly (MEA) was fabricated using the formed catalyst layer. This fabricated MEA was incorporated into a fuel cell, and a power generation test was performed using a fuel cell measuring device. The preparation of each component and the cell evaluation through the power generation test are described in detail below.

[0092] (1) Preparation of catalyst (platinum-supported carbon material) for polymer electrolyte fuel cell The catalyst support carbon material of each example was dispersed in distilled water, formaldehyde was added to this dispersion, and the dispersion was placed in a water bath set at 40°C. After the temperature of the dispersion reached 40°C, the same as the bath temperature, an aqueous solution of dinitrodiamine Pt complex nitric acid was slowly poured into the dispersion under stirring. Stirring was continued for about 2 hours, followed by filtration and washing of the resulting solid. The solid thus obtained was vacuum dried at 90°C, pulverized in a mortar, and then heat-treated at 200°C for 1 hour in an argon atmosphere containing 5% by volume of hydrogen to produce a platinum-supported carbon material. The amount of platinum carried on this platinum-supporting carbon material was adjusted to 35 mass % with respect to the total mass of the catalyst carrier carbon material and platinum particles, and was confirmed by measurement using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0093] (2) Preparation of Catalyst Layer Using the platinum-supported carbon material (Pt catalyst) prepared as described above and a 5 mass % Nafion solution (DE2020CS, registered trademark: Nafion, manufactured by DuPont) as the electrolyte resin, the Pt catalyst and Nafion were mixed under an Ar atmosphere in a ratio of 1.0 times the mass of the Nafion solid content relative to the mass of the porous carbon black (the mass of only the porous carbon black in the Pt catalyst excluding the Pt content), and after light stirring, the Pt catalyst was crushed by ultrasonic waves. Ethanol was further added to adjust the total solid content concentration of the Pt catalyst and the electrolyte resin to 0.5 mass %, thereby preparing a catalyst layer ink liquid in which the Pt catalyst and the electrolyte resin were mixed.

[0094] Using the catalyst layer ink liquid prepared in this manner, the spray conditions were adjusted so that the mass of platinum per unit area of ​​the catalyst layer (hereinafter referred to as "platinum coverage") was 0.2 mg / cm, and the catalyst layer ink was sprayed onto a Teflon (registered trademark) sheet, followed by a drying treatment in argon at 120°C for 60 minutes to produce a catalyst layer.

[0095] (3) Fabrication of MEA Using the catalyst layers prepared as described above, an MEA (membrane electrode assembly) was fabricated using the following method. A square electrolyte membrane with sides of 6 cm was cut out from a Nafion membrane (NR211 manufactured by DuPont). The anode and cathode catalyst layers, coated on Teflon® sheets, were each cut out into a square with sides of 2.5 cm using a utility knife. The electrolyte membrane was sandwiched between the anode and cathode catalyst layers so that the catalyst layers were in contact with each other across the center of the electrolyte membrane and were not misaligned with each other. The assembly was pressed at 120°C and 100 kg / cm2 for 10 minutes, cooled to room temperature, and then the Teflon® sheets were carefully peeled off from both the anode and cathode. This produced a catalyst layer-electrolyte membrane assembly in which the anode and cathode catalyst layers were fixed to the electrolyte membrane.

[0096] Next, a pair of square carbon paper sheets, each 2.5 cm on a side, was cut out from carbon paper (39BC manufactured by SGL Carbon Co., Ltd.) to form a gas diffusion layer. The catalyst layer-electrolyte membrane assembly was sandwiched between these carbon paper sheets so that the anode and cathode catalyst layers were aligned with each other without any misalignment. The assembly was then heated at 120°C and 50 kg / cm ２ The membrane was pressed for 10 minutes at 100°C to prepare an MEA. The basis weight of each of the catalytic metal component, carbon material, and electrolyte material in each prepared MEA was calculated from the mass of the catalyst layer fixed to the Nafion membrane (electrolyte membrane) obtained by calculating the mass of the catalyst layer from the difference between the mass of the Teflon (registered trademark) sheet with the catalyst layer before pressing and the mass of the Teflon (registered trademark) sheet peeled off after pressing, and the mass ratio of the catalyst layer composition.

[0097] (4) Fuel Cell Assembly and Initial Power Generation Performance Evaluation The MEAs fabricated using the porous carbon materials according to each Example and Comparative Example were assembled into cells and set in a fuel cell measuring device. The initial power generation performance of the fuel cells was evaluated according to the following procedure. Air was supplied to the cathode side and pure hydrogen was supplied to the anode side. The pressure was adjusted using a back-pressure valve installed downstream of the cell to achieve utilization rates of 40% and 70%, respectively, so that the back-pressure gauge pressure was 0.1 MPaG. The cell temperature was set to 80°C, and the air and pure hydrogen supplied to the fuel cell were humidified by passing them through distilled water kept at 80°C in a humidifier (i.e., bubbling). This set the relative humidity of the anode and cathode to approximately 100%. Under these settings, the reactant gas was supplied to the cell. The current density was gradually increased 10 times until the cell terminal voltage reached 0.3 V. Thereafter, the current density was increased to 0.2 A / cm. ２ The cell terminal voltage was recorded when the current density was fixed at 0.2 A / cm and held for 10 minutes, and the low load performance was evaluated using the following criteria: pass rank A or B, and fail rank C. The results are shown in Table 1. [Pass rank] A: Current density 0.2 A / cm ２ B: The voltage between the cell terminals is 0.83 V or more at a current density of 0.2 A / cm ２ The voltage between the cell terminals is 0.81 V or more. [Failure rank] C: Not meeting the pass rank B.

[0098] (5) Durability Evaluation After the initial power generation performance evaluation, a durability test was conducted under the following conditions. First, the cell temperature was 80°C, the relative humidity was 100%, the cell back pressure was 0.0 MPaG, and the cathode gas was switched to argon gas. Next, the cell voltage was set to 0.6 V and held for 4 seconds, followed by a cycle of setting the cell voltage to 1.2 V and holding for 4 seconds. This square-wave voltage fluctuation was repeated 1,000 cycles. The anode and cathode gas utilization rates were then set to 40% and 70%, respectively, the cell back pressure gauge pressure was 0.1 MPaG, the cell temperature was 80°C, and the relative humidity was 100%. The current density was recorded when the cell voltage was set to 0.3 V. Durability evaluation was performed using the following criteria: pass ranks A and B, and fail rank C. The results are shown in Table 1. [Pass Rank] A: The current density after 1,000 cycles was 80% or more of the current density during the initial power generation performance evaluation. B: The current density after 1000 cycles is 70% or more of the current density at the time of initial power generation performance evaluation. [Failure Rank] C: Not meeting the pass rank B.

[0099]

[0100]

[0101] From the above results, it can be seen that the carbon material for a catalyst carrier of the example (that is, porous activated carbon black) can achieve both high durability and low load characteristics.

[0102] The symbols are explained as follows: 100: polymer electrolyte fuel cell 110, 120: separator 130, 140: gas diffusion layer 150, 160: catalyst layer 170: electrolyte membrane

[0103] The disclosure of Japanese Patent Application No. 2023-108951 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A carbon material for a catalyst support in a polymer electrolyte fuel cell, comprising a porous activated carbon black that satisfies the following requirements (A), (B), and (C): (A) a BET specific surface area of ​​350 m ２ / g or more 800m ２ (B) The pore volume VD of pores having a pore diameter of 5 nm or more and 20 nm or less, which is determined by analyzing the nitrogen desorption isotherm using the Dollimore-Heal (DH) method, is ５－２０ The pore volume VA of pores with a pore diameter of 20 nm or less obtained by analyzing the nitrogen adsorption isotherm using the Dollimore-Heal (DH) method ２０ The value divided by (VD ５－２０ / V.A. ２０ (C) In a thermogravimetric differential thermal analysis (TG-DTA), the temperature Td at which the weight of the material decreases by 10% when the temperature is increased at 10° C. / min in an air atmosphere is 0.35 or less. １０％ is 620 to 680°C.

2. The pore volume VA ２０ 2. The carbon material for a catalyst support of a polymer electrolyte fuel cell according to claim 1, wherein the molecular weight is 0.36 to 0.90 mL / g.

3. A catalyst layer for a polymer electrolyte fuel cell comprising the carbon material for a catalyst support of a polymer electrolyte fuel cell according to claim 1 or 2.

4. A fuel cell comprising the catalyst layer for a polymer electrolyte fuel cell according to claim 3.

5. The fuel cell according to claim 4, wherein the catalyst layer for the solid polymer electrolyte fuel cell is a catalyst layer on the cathode side.