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

Abstract

Provided is a carbon material for a catalyst carrier in a solid polymer fuel cell, the carbon material comprising porous activated carbon black satisfying requirements (A) to (C). (A) The BET surface area (m2 / g) measured by nitrogen gas adsorption is 400-1200. (B) In a particle size distribution of the accumulated passing amount of particles from small particles to large particles obtained by volume-based particle size using a laser light scattering method, the difference Δ=D95-D5 is 0.35-2.00, where D5 (μm) and D95 (μm) are common logarithm values of particle size for 5% and 95% accumulated passing amounts, respectively, when the total accumulated amount is 100%. (C) In a Raman spectrum obtained by Raman spectroscopy, the full width at half maximum ΔG (cm-1) of G-band in the range of 1560 cm-1 to 1620 cm-1 is 72-90.

Description

[Technical Field]

[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. [Background technology]

[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 fuel gas such as hydrogen is introduced into the separator on the anode side. The fuel is diffused into the gas diffusion layer on the anode side before being introduced into the anode. The anode contains a catalyst component, a catalyst support that supports a fuel cell catalyst, and an electrolyte material with proton conductivity. Hereinafter, the catalyst component that promotes the power generation reaction (oxidation reaction or reduction reaction described below) in the fuel cell will also be referred to as the "fuel cell catalyst." The catalyst support is often made of a porous carbon material. An oxidation reaction of the fuel gas occurs on the fuel cell catalyst, producing protons and electrons. For example, when the fuel gas becomes hydrogen gas, the following oxidation reaction occurs: H2→2H + +2e - (E0=0V)

[0004] The protons produced in this oxidation reaction are introduced to the cathode through the electrolyte material (ionomer) in the anode and the solid polymer electrolyte membrane. Electrons are introduced to the external circuit through the catalyst support, gas diffusion layer, and separator. After performing work in the external circuit, these electrons are introduced to the separator on the cathode side. These electrons then pass through the separator on the cathode side and the gas diffusion layer on the cathode side and are introduced to 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. An oxidizing gas, such as oxygen gas or air, is introduced into the cathode-side separator. The oxidizing gas is diffused into the cathode-side gas diffusion layer and then introduced into the cathode. The cathode includes a fuel cell catalyst, a catalyst support that supports the fuel cell catalyst, and a proton-conductive electrolyte material. The catalyst support is often made of a porous carbon material. A reduction reaction of the oxidizing gas occurs on the fuel cell catalyst, producing water. For example, when the oxidizing gas becomes oxygen gas or air, the following reduction reaction occurs: O2+4H + +4e - →2H2O (E0=1.23V)

[0006] 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 free energy difference (potential difference) generated by the oxidation reaction of the fuel gas. In other words, the free energy generated by the oxidation reaction is converted into work performed by electrons in an external circuit.

[0007] Meanwhile, porous carbon materials (hereinafter also referred to as "carbon supports") that can be used as catalyst supports for polymer electrolyte fuel cells have been studied and various proposals have been made.

[0008] For example, Patent Document 1 states, "A method for producing high surface area graphitized carbon, "A method of producing leaded carbon, comprising, in either order, graphitizing a starting carbon material, optionally carbon black, and increasing the surface area, wherein the increasing surface area is accomplished by oxidation or removal of a template phase."

[0009] Patent Document 2 proposes "a method for increasing the surface area of ​​carbon black, the method comprising contacting a carbon black starting material having a first BET nitrogen surface area with an oxidizing agent 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."

[0010] Patent Document 3 proposes "a method for producing a catalyst ink to be applied to both sides of an electrolyte membrane of a fuel cell, comprising: (1) a step of stirring a suspension solution obtained by mixing catalyst-supported particles formed from activated carbon black and carrying a catalyst, an electrolyte, and a solvent for suspending the catalyst-supported particles, the catalyst, and the electrolyte; and (2) a step of dispersing the suspension solution using an ultrasonic homogenizer, wherein in step (2), the dispersion treatment is carried out at a higher output than normal treatment so that, in a frequency distribution of the particle sizes of the catalyst-supported particles in the catalyst ink as measured by a laser diffraction particle size distribution measurement method, there is a first peak in a particle size range of 1 micrometer or less, and there is no peak in a particle size range exceeding 1 micrometer that is ¼ or more of the height of the first peak."

[0011] Patent Document 4 proposes "a carbon material for catalyst supports, which is used as a catalyst support for a polymer electrolyte fuel cell and has a three-dimensionally branched dendritic structure, and is characterized in that the carbon material for catalyst supports simultaneously satisfies the following (1) and (2)." (1) In particle size distribution measurement using a laser diffraction / scattering particle size analyzer, the cumulative distribution [%] of particles with a particle diameter of 1 μm or less based on volume diameter is DL, and the cumulative distribution [%] of particles with a particle diameter of more than 1 μm is DH, and the DL / DH ratio is 1.5 or more. (2) The mode diameter of the pores in the range of 20 nm to 200 nm in diameter measured by the mercury porosimetry method is 40 nm to 70 nm.

[0012] Patent Document 1: Special Publication No. 2011-514304 Patent Document 2: Special Publication No. 2011-515507 Patent Document 3: Patent No. 5790537 Patent Document 4: Japanese Patent Application Laid-Open No. 2022-156985 Summary of the Invention [Problem to be solved by the invention]

[0013] The ability of polymer electrolyte fuel cells (PEFCs) to achieve both power generation characteristics and durability is an important characteristic for the widespread adoption of fuel cell vehicles (FCVs), and this is an essential issue to be resolved, particularly for commercial vehicles, where market growth is expected in the future.

[0014] Generally, one of the main causes of the deterioration of PEFC durability is catalyst degradation, which is caused by the oxidative consumption of the carbon support and the dissolution of platinum nanoparticles. Both of these factors are caused by electrode potential fluctuations, especially potential fluctuations in the high potential range exceeding 1 V. The solution to platinum dissolution is to increase the particle size to buy more time for dissolution. The solution to the problem of oxidative wear of carbon supports is to suppress wear due to oxidation by increasing the crystallinity (i.e., increasing the in-plane size of the crystallites and the thickness of the layers) and thereby reducing the area of ​​the edges of the carbon network plane, which are the starting points for oxidative wear, thereby slowing down the oxidation rate.

[0015] The power generation characteristics are mainly governed by two factors: the contribution of the metal catalyst (e.g., platinum nanoparticles) to the reaction (hereinafter also referred to as "catalyst utilization rate") and the diffusibility of the oxidizing gas. The pore structure of the carbon support (porous carbon material) correlates with the catalyst utilization rate, and the three-dimensional structure of the carbon support (e.g., dendritic structure) correlates with the gas diffusivity. The pore structure should preferably have only pores of a size sufficient to accommodate metal catalysts (such as platinum nanoparticles) of a few nanometers in size, and mesoporous carbon is generally considered to be a suitable support. Although the pore size suitable for gas diffusion is unclear, the pore size of the catalyst layer for nucleic acids is estimated to be around several tens to 100 nm based on the various carbon supports currently in use. The pores in the catalyst layer are realized by the three-dimensional structure of the carbon support (specifically, the aggregate structure of carbon black, etc.). To increase the crystallinity of carbon supports, they are heat-treated in an inert gas atmosphere at temperatures above 1500°C, preferably above 2000°C, to increase the crystallite size. However, this process has the side effect of collapsing the pores as the crystals grow. The greater the degree of crystal growth, the greater the degree of pore collapse.

[0016] Among carbon supports (porous carbon materials), porous carbon black is one of the inexpensive and useful materials. Carbon black has a minimum structural unit called an aggregate, which is a structure in which primary particles of several tens of nanometers in size are chemically fused together in an average of 10 to 20 particles. Since aggregates are fine powders that do not easily fall off once suspended in the air, which makes them an aerosol, they are usually granulated before use to make them suitable for industrial handling. To use carbon black as a catalyst support for fuel cells, it is necessary to activate it to make it porous and then heat-treat it to increase its crystallinity. However, the inventors have confirmed that aggregates chemically bond together during the heat-treatment process, and this tendency is more pronounced as the primary particles become smaller.

[0017] The porous carbon black that aggregates during this heat treatment (hereinafter referred to as "thermal aggregation") is not disintegrated during the process of forming the catalyst layer, and the thermally aggregated lumps remain until the end. Thermal agglomerates in the catalyst layer reduce the number of pores with diameters of several tens to 100 nm that should be formed in the catalyst layer due to the aggregate structure, and smaller pores that are not suitable for gas diffusion are formed in the thermal agglomerates, resulting in a significant decrease in power generation characteristics (especially high load characteristics) when passing large currents.

[0018] Thus, it is necessary to improve power generation characteristics, particularly high-load characteristics, by avoiding thermal aggregation of carbon black during heat treatment to improve durability. However, the catalyst layer is made by the manufacturer that fabricates the stack, and manufacturers that supply catalyst supports rarely intervene in the ink dispersion process used to form the catalyst layer. Therefore, the development of porous carbon black that is easy to disperse or has fewer agglomerates formed by the aggregation of aggregate particles has not yet been considered, compared to the need to achieve both a good pore structure and crystallinity development.

[0019] For example, as shown in Patent Documents 1 and 2, manufacturing methods have been studied that enable carbon black to be used as a porous carbon material for catalyst supports in polymer electrolyte fuel cells. However, no studies have been conducted from the perspective of eliminating thermal agglomerates, and the manufacturing methods have been devised simply within the scope of common sense guidelines in the field, namely, a combination of activation to make the carbon black porous and heat treatment. Patent Document 3 is an improvement related to a manufacturing method for improving dispersion in ink production, but in this case, a new problem arises in which the three-dimensional structure of the carbon support is mechanically destroyed, so it does not fundamentally solve the problem of thermal agglomerations. Patent Document 4 describes CO2 activation and mechanical crushing and classification for the combustion of amorphous carbon known as soot, but this method does not provide a fundamental solution to the problem of thermal agglomeration because it creates a new problem of mechanically destroying the three-dimensional structure of the carbon support.

[0020] As described above, there is still much room for improvement in durability as well as power generation characteristics (particularly high load characteristics), and further improvements are currently desired.

[0021] Therefore, an object of the present disclosure is to provide a carbon material for a catalyst support of a polymer electrolyte fuel cell that has excellent durability as well as power generation characteristics (particularly, high-load characteristics), a catalyst layer for a polymer electrolyte fuel cell that uses the same, and a fuel cell. [Means for solving the problem]

[0022] The means for solving the problem include the following aspects. <1> A carbon material for a catalyst support in a polymer electrolyte fuel cell, comprising porous activated carbon black that satisfies the following requirements (A), (B), and (C): (A) BET surface area (m) measured by nitrogen gas adsorption 2 / g) is 400 or more and 1200 or less. (B) In the particle size distribution of the cumulative amount of passing particles from small particles to large particles obtained by the volume-based particle size measurement using the laser light scattering method, when the total cumulative amount is set to 100%, the common logarithm of the particle size when the cumulative amount of passing particles is 5% and 95%, respectively, is defined as D5 (μm) and D 95 (μm), the difference Δ=D 95 -D5 is equal to or greater than 0.35 and equal to or less than 2.00. (C) In the Raman spectrum obtained by Raman spectroscopy, the peak at 1560 cm -1 ~1620cm -1 The full width at half maximum of the G band, ΔG (cm -1 ) is between 72 and 90. <2> In addition, the following requirement (D) must be met: <1> 2. The carbon material for a catalyst support of a polymer electrolyte fuel cell according to claim 1. (D) In ​​the particle size distribution of the passing accumulated amount, the common logarithm of the particle size when the passing accumulated amount is 50% is defined as D 50 (μm), the common logarithm of the mode diameter is D mode (μm), (D 50 -D mode ) / D 50 However, it is between -0.16 and 0.20. <3> <1> or <2> 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. <4> <3> A fuel cell comprising the catalyst layer for a polymer electrolyte fuel cell according to claim 1. <5> The catalyst layer for a polymer electrolyte fuel cell is a catalyst layer on the cathode side. <4> The fuel cell according to claim 1. [Effects of the Invention]

[0023] According to the present disclosure, there are provided a carbon material for a catalyst support in a polymer electrolyte fuel cell that has excellent durability as well as power generation characteristics (particularly high load characteristics), a catalyst layer for a polymer electrolyte fuel cell that uses the same, and a fuel cell. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram showing an example of the general configuration of a fuel cell according to the present disclosure. [Figure 2] FIG. 2 is a graph showing an example of particle size distribution of the cumulative amount of passing particles from small particles to large particles obtained by the volume-based particle size measurement using the laser light scattering method, and is a graph for explaining the common logarithm of the particle diameter when the cumulative amount of passing particles is 5%, the common logarithm of the particle diameter when the cumulative amount of passing particles is 95%, the common logarithm of the particle diameter when the cumulative amount of passing particles is 50%, the common logarithm of the particle diameter when the cumulative amount of passing particles is 50%, and the common logarithm of the mode diameter, Dmode. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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 the numerical values ​​written before and after "to" are followed by "greater than" or "less than," the numerical range does not include these numerical values ​​as the lower or upper limit. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In the present disclosure, the "electrolyte material having proton conductivity" used in the catalyst layer of a fuel cell is also referred to as an "ionomer."

[0026] <Carbon materials for catalyst supports in polymer electrolyte fuel cells> The carbon material for a catalyst support of a polymer electrolyte fuel cell according to the present disclosure is made of porous activated carbon black that satisfies the requirements (A), (B), and (C) described below. Here, the porous activated carbon black is carbon black that has been made porous by activation. The porous activated carbon black is also called "porous carbon black."

[0027] The carbon material for a catalyst support according to the present disclosure is a carbon material that has excellent durability as well as power generation characteristics (particularly high load characteristics). The carbon material according to the present disclosure was discovered based on the following findings.

[0028] First, the inventors investigated the heat treatment of porous carbon black and obtained the following findings. First, heat treatment not only causes pore collapse, but also causes agglomeration of the porous carbon black, which contributes to a decrease in power generation characteristics to the same extent as pore collapse. Specifically, there are cases where the power generation characteristics are significantly reduced despite only minor pore collapse, and in such cases, the particle size distribution contains thermal agglomerates whose average particle size is clearly larger than that before the heat treatment.The thermal agglomerates can be detected with high accuracy by so-called particle size distribution measurement.

[0029] Meanwhile, the inventors have investigated methods for eliminating thermal agglomerates in the particle size distribution of porous carbon black, and as a result, have made the following findings. Thermal agglomerates are thought to arise because the contact points between aggregates form chemical bonds during the heat treatment process. Therefore, the solution to this problem is to selectively remove only the bonding points. A specific method that is effective is selective combustion of the carbon surface. A suitable treatment for selectively burning the carbon surface is to treat the thermal agglomerates in an atmosphere containing ozone (also simply referred to as "ozone") as an oxidizing agent, thereby achieving surface combustion with little change in the pore structure.As a result, when the particle size distribution of the thermal agglomerates after ozone treatment is measured, a particle size distribution that reflects the aggregate size can be achieved.

[0030] In ozone treatment, the main reaction control variables are the concentration of the mixed gas of ozone gas and an inert gas (such as argon gas), the reaction temperature, and the flow rate. Ozone has a very strong oxidizing power, so in the case of porous carbon materials, the treatment is carried out at room temperature (25°C), with an ozone concentration of several volume percent to 10 volume percent, a reaction time of several hours, and the flow rate adjusted so that the mass loss is 5 mass percent or less. By treating under these conditions, the pore structure remains unchanged by nitrogen gas adsorption, and the particle size distribution of the aggregates is significantly improved, resulting in a particle size distribution that reflects the aggregate structure. Here, the particle size distribution is generally used, with particle frequency being the volume, and the vertical axis representing the volume frequency and the horizontal axis representing the common logarithm of the particle diameter.

[0031] The particle size distribution reflects the aggregate structure, and although particle size distribution is based on empirical theory, in principle, symmetry is ideal, and the mode diameter is a size that reflects the aggregate diameter, which is an aggregation of primary particle diameters. If carbon black with a well-developed dendritic structure is used to increase the pore volume of the catalyst layer, the mode diameter should ideally be in the range of 5 to 13 times the primary particle diameter. In this way, porous carbon black as a catalyst support carbon material is obtained by activating and heat-treating raw carbon black, and the aggregate is the smallest unit, making it possible to achieve a particle size distribution that reflects the aggregate structure.

[0032] Therefore, the inventors investigated whether the proportion of thermally agglomerated masses that are disintegrated is high, because this is important for battery characteristics, and as a result, they obtained the following findings. The distribution width of the particle size distribution of the cumulative amount of passing porous carbon black from small particles to large particles, obtained by volume-based particle size measurement using laser light scattering, can be defined as the particle sizes at 5% and 95% of the cumulative amount of passing particles falling within a certain range, when the total cumulative amount is taken as 100%. The shape of the particle size distribution is expressed as a common logarithm of the particle size on the horizontal axis, and the symmetry of the distribution is obtained by expressing the common logarithm of the particle size on the horizontal axis. Therefore, the particle size ranges at 5% and 95% are specified as numerical ranges on a common logarithm scale of the particle size.

[0033] Generally, the power generation characteristics of a fuel cell depend heavily on the overvoltage of the cathode reaction. The following three factors are thought to be the main causes of overvoltage at the cathode: (1) The magnitude of the ohmic resistance of the catalyst layer is the combination of two resistances: electron conduction resistance and proton conduction resistance. (2) Diffusion resistance of oxidizing gases within the catalyst layer (3) Electrochemical reactions on the catalytic metal surface, i.e., chemical reactions involving electron transfer (proton oxidizing gas diffusion)

[0034] "(2) Diffusion resistance of oxidizing gases within the catalyst layer" can be improved by the dispersion state of porous carbon black as a carbon support. As mentioned above, the cause of poor dispersion of porous carbon black is the formation of thermal agglomerates during the heat treatment process, which is a side effect of chemically bonding contact points between aggregate particles, the smallest units of porous carbon black. Selective combustion of the surface of porous carbon black is an effective way to selectively remove contact points, and ozone oxidation is an effective way to achieve this. Optimizing ozone treatment can achieve a dispersion state equivalent to that before heat treatment.

[0035] In other words, by using ozone gas, which has a high oxidative reactivity with carbon, and optimizing the conditions for highly selective oxidation of the raw carbon black surface, we were able to successfully oxidize and consume the surface layer. As a result, we were able to selectively remove the adhered portions of the surface that formed thermal agglomerates, thereby achieving a particle size distribution in which the agglomerates were broken down. In other words, the particle size distribution of the porous carbon black obtained by ozone oxidation can achieve the same particle size distribution as that of the raw carbon black. In addition to the specific surface area, power generation characteristics (particularly high load characteristics) can be improved by breaking down thermal agglomerates.

[0036] In addition, the full width at half maximum of the G band in the Raman spectrum obtained by Raman spectroscopy, ΔG (cm -1 ) within a predetermined range, durability is also improved.

[0037] 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 is excellent in durability as well as in power generation characteristics (particularly, high load characteristics).

[0038] The carbon material for a catalyst support (i.e., porous activated carbon black) of the present disclosure is easily crushed in the ink preparation step for forming a catalyst layer, making it possible to prepare a well-dispersed ink with few thermal agglomerates. In this disclosure, in order to determine whether a carbon material for a catalyst support disperses easily in ink, as will be described in the examples below, a method was adopted in which the carbon material for a catalyst support was dispersed in a 10 mass % Liponox solution (aqueous solution of Liponox CN, a polyoxyalkylene phenyl ether type surfactant manufactured by Lion Corporation) using an ultrasonic disperser to prepare a dispersion for measuring particle size distribution. The particle size distribution of the dispersion obtained by this preparation method is measured by laser light scattering. If a particle size distribution reflecting the aggregate structure is obtained, it is expected that dispersion will be easily achieved in the ink production process.

[0039] Requirements (A), (B), and (C) are explained below. Here, from the viewpoint of further improving durability in addition to power generation characteristics (particularly, high-load characteristics), it is preferable that the carbon material for a catalyst support of the present disclosure satisfies requirement (D) in addition to requirements (A), (B), and (C).

[0040] (Requirement (A)) (A) BET surface area (m) measured by nitrogen gas adsorption 2 / g) is 400 or more and 1200 or less.

[0041] The BET specific surface area of ​​porous carbon black is 1200m 2If the carbon density exceeds 1 / g, the thickness of the carbon walls that form the pore structure becomes thin. Specifically, the average number of layers on the carbon network surface becomes 3 or less, resulting in weak mechanical strength. Furthermore, when the carbon walls are oxidized and consumed by a nano-sized catalyst metal (i.e., an alloy mainly composed of platinum), the number of layers becomes thin, making the structure more susceptible to structural destruction even though the amount of carbon consumed is small. This accelerates the deterioration of power generation characteristics due to durability. The BET specific surface area of ​​porous carbon black is 400m 2 If the surface area is less than 1 / g, it becomes impossible to support as many catalyst particles as possible within the carbon black particles, which is an advantage of porous carbon materials. As a result, more carbon black particles are required to support the same number of catalyst particles. In other words, the catalyst layer becomes thicker. As a result, the diffusion distance of oxidizing gas within the catalyst layer becomes longer, leading to a decrease in high-load performance.

[0042] The BET specific surface area of ​​the porous carbon black is preferably 450 m 2 / g or more 1150m 2 / g or less.

[0043] The BET specific surface area is a value measured by the method described in the Examples below.

[0044] (Requirement B) (B) In the particle size distribution of the cumulative amount of passing particles from small particles to large particles obtained by the volume-based particle size measurement using the laser light scattering method, when the total cumulative amount is set to 100%, the common logarithm of the particle size when the cumulative amount of passing particles is 5% and 95%, respectively, is defined as D5 (μm) and D 95 (μm), the difference Δ=D 95 -D5 is equal to or greater than 0.35 and equal to or less than 2.00.

[0045] The importance of using particle size distribution measurement by laser light scattering is twofold. First, the process of dispersing porous carbon black in water requires much less energy than the ink production process, and if good dispersion is achieved in this dispersion process, even better dispersion can be achieved in the ink used to form the catalyst layer. Second, the particle size distribution equivalent to the size distribution of porous carbon black can be quantitatively measured by the laser light scattering method. That is, if the porous carbon black satisfies the above particle size distribution range, the porous carbon black will not aggregate but will be dispersed as individual particles.

[0046] Porous carbon black difference Δ=D 95 The lower limit of -D5 is essentially 0.35. No carbon black exists that has a value smaller than this. This is the theoretical lower limit of the raw carbon black produced by the furnace process, and the porous carbon black produced from this raw carbon black cannot exceed the lower limit of the raw carbon black. Porous carbon black difference Δ=D 95 -D5 is greater than 2.00, which indicates significant aggregation. 95 This indicates that D5 is large or that aggregates, the smallest units of carbon black, are destroyed, resulting in a small D5. Both significant aggregation and destruction of the aggregate structure reduce power generation characteristics. Porous carbon black difference Δ=D 95 −D5 is preferably 0.35 or more and 1.9 or less, more preferably 0.35 or less and 0.91 or less, and even more preferably 0.35 or more and 0.85 or less.

[0047] Here, the common logarithm value D5 (μm) of the particle diameter is preferably −1.2 or more and −0.6 or less, and more preferably −1.1 or more and −0.7 or less.

[0048] The volume-based particle size distribution measured by the laser light scattering method is a value measured by the method described in the Examples section below.

[0049] (Requirement C) (C) In the Raman spectrum obtained by Raman spectroscopy, the peak at 1560 cm -1 ~1620cm -1 The full width at half maximum of the G band, ΔG (cm -1 ) is between 72 and 90

[0050] Porous carbon black as a catalyst support is required to have the durability of a fuel cell, i.e., to be resistant to two types of oxidation when held at a high potential of more than 1 V: (1) resistance to oxidative attenuation of the porous carbon black, and (2) resistance to localized oxidative attenuation at the site of contact with the nano-sized catalytic metal when supported on the porous carbon black. A fundamental and effective measure to enhance this resistance is to improve the crystallinity of porous carbon black. Improved crystallinity leads to an increase in the size of the carbon network plane and an increase in the number of layers, which both improves oxidation wear resistance.

[0051] In Raman spectroscopy of porous carbon black, the D band (1300-1400 cm) reflects the size of the edge area of ​​the carbon network plane. -1 ) peak and the G band (1560-1620 cm ) that reflects the size and number of carbon lattice layers. -1 ) peak, it is possible to obtain information about the crystallinity of porous carbon black. When porous carbon black made porous through activation is heat-treated at 1600-1900°C in an inert gas atmosphere (also known as graphitization treatment), the linewidth of the G band sensitively reflects changes in crystallinity due to the heat treatment.

[0052] The full width at half maximum of the G band of porous carbon black, ΔG, is 90 cm -1 If the temperature exceeds this value, the oxidation resistance of the porous carbon black decreases, resulting in an increase in overvoltage at high currents and a decrease in high-load characteristics. The G band of porous carbon black is 72 cm -1 If the temperature is less than 100°C, the porous carbon black, which is basically difficult to crystallize due to the increased porosity, will be treated at a higher temperature, which may result in the requirements (A) and (B) not being satisfied. The full width at half maximum of the G band of porous carbon black, ΔG (cm -1) is preferably 72 or more and 89 or less, more preferably 72 or more and 88 or less, even more preferably 72 or more and 82 or less, particularly preferably 72 or more and 81 or less, and most preferably 72 or more and 80 or less.

[0053] The full width at half maximum of the G band, ΔG, is a value measured by the method described in the Examples below.

[0054] (Requirement D) (D) In ​​the particle size distribution of the cumulative amount of passing particles from small particles to large particles obtained by the volume-based particle size measurement using laser light scattering, the common logarithm of the particle size when the cumulative amount of passing particles is 50% is defined as D. 50 (μm), the common logarithm of the mode diameter is D mode (μm), (D 50 -D mode ) / D 50 However, it is between -0.16 and 0.20.

[0055] The particle size distribution of raw carbon black is nearly symmetrical between the small particle side and the large particle side, with the mode diameter as the symmetrical axis when the particle diameter (μm) on the horizontal axis is expressed in common logarithm. Therefore, if there are few thermal agglomerates of porous carbon black, a symmetrical particle size distribution is the desired state. The ideal particle size distribution symmetry determined from the power generation characteristics is D 50 and D mode Difference of D 50 In other words, if it is symmetric, (D 50 -D mode ) / D 50 = 0, median diameter D 50 If the frequency of small particles is high, the difference becomes negative, and if the frequency of large particles is high, the difference becomes positive. The upper limit of the breakdown of symmetry is -0.16 on the negative side and 0.20 on the positive side.

[0056] Porous carbon black "(D 50 -D mode ) / D 50When the value of " is -0.16 or more, thermal agglomerates are sufficiently broken down, the frequency of large particles is reduced, gas diffusion in the catalyst layer increases, and power generation characteristics, particularly high load characteristics, are improved. Porous carbon black "(D 50 -D mode ) / D 50 When the value of " is 0.20 or less, thermal agglomerates are sufficiently broken down, the frequency of large particles is reduced, gas diffusion in the catalyst layer increases, and power generation characteristics, particularly high load characteristics, are improved. Porous carbon black "(D 50 -D mode ) / D 50 " is more preferably in the range of -0.14 to 0.18, and even more preferably in the range of -0.12 to 0.16.

[0057] Here, the common logarithm of the particle diameter is D 50 (μm) is preferably −1.70 or more and −1.00 or less, and more preferably −1.50 or more and −1.10 or less.

[0058] The volume-based particle size distribution measured by the laser light scattering method is a value measured by the method described in the Examples section below.

[0059] The volume-based particle size distribution measured by the laser light scattering method is a value measured by the method described in the Examples section below.

[0060] <Method for producing carbon material for catalyst support of polymer electrolyte fuel cells> An example of a method for producing a carbon material for a catalyst support of a polymer electrolyte fuel cell according to the present disclosure (hereinafter also referred to as a "carbon material production method") will be described below.

[0061] The method for producing a carbon material according to the present disclosure is, for example, a method including the following three steps. The method for producing a carbon material according to the present disclosure can provide a carbon material that satisfies requirements (A) to (C), and preferably a carbon material that satisfies requirements (A) to (C) as well as at least one of requirements (D) and (E) (i.e., porous activated carbon black). Activation process: This is a process in which raw carbon black is activated to make it porous. Heat treatment step: A heat treatment step in which the raw carbon black that has been made porous in the activation step (hereinafter also referred to as porous raw carbon black) is heat treated. Ozone treatment process: This process oxidizes the porous raw carbon black that has been heat-treated in the heat treatment process (hereinafter referred to as heat-treated porous raw carbon black) with ozone.

[0062] Each step will be described in detail below. First, the raw material carbon black used will be described.

[0063] (raw carbon black) As the raw material carbon black, carbon black that satisfies the three specified structures described below, namely, primary particle size, three-dimensional structure (aggregate structure formed by linked primary particles), and granulation state, can be suitably used.

[0064] -Primary particle size- The size of the voids in the catalyst layer is determined by the three-dimensional structure and primary particle diameter of the raw material carbon black. In other words, since the three-dimensional structure is created by a chain of primary particles, the void size is calculated as follows: primary particle diameter x number of beads = void size. If a three-dimensional structure is developed and the primary particle diameter is 20 nm or more, gas diffusion in the catalyst layer will not become rate-limiting and the power generation characteristics will not deteriorate. In other words, the preferred range of the primary particle diameter is 20 nm or more and 80 nm or less. If the primary particle diameter exceeds 80 nm, it will be difficult to develop a three-dimensional structure, so 80 nm is the practical limit for production. It is assumed that pore formation by activation occurs from the outside to the inside, and since the surface area is continuously exposed to oxidation treatment, there is a large loss due to combustion. If this is the case, the larger the primary particle size, the more pores with smaller diameters will be formed in the interior, but the more pores with a relatively large diameter will tend to be formed near the surface. In fact, when raw carbon black with a large primary particle size is activated, pore development is weaker than with smaller particle sizes, even if the mass is reduced. In other words, the larger the primary particle size, the more difficult it is to increase the BET surface area. On the other hand, although the mechanism is not entirely clear, if the crystallinity measured by Raman or X-ray diffraction is the same, raw carbon black with a larger primary particle size has higher resistance to oxidative wear than raw carbon black with a smaller primary particle size. In other words, the larger the primary particle size, the greater the durability. In particular, raw carbon black with a primary particle size exceeding 40 nm is effective in improving durability. Raw carbon black with a primary particle size of 50 nm or more is effective in significantly improving durability, and raw carbon black with a primary particle size exceeding 60 nm is effective in significantly improving durability.

[0065] The primary particle size of the raw material carbon black is one of the basic physical properties, and reference is made to the primary particle size values ​​in the catalogue of the carbon black manufacturer. However, if the values ​​in the carbon black manufacturer's catalog cannot be referenced, the arithmetic mean diameter of primary particles is calculated from images of primary particles measured with an electron microscope, as recommended by the Carbon Black Association, i.e., the method described in the Carbon Black Yearbook. More specifically, we referred to "i. Electron Microscope Photography Method," "ii. Particle Size Measurement," and "iii. Particle Size Calculation Method" on page 176 of the Carbon Black Handbook (edited by the Carbon Black Association, first published in 1971). To obtain a statistical average, the sizes of at least 100 primary particles are measured, and the arithmetic mean is determined as the primary particle diameter d. The arithmetic mean diameter is calculated using the following formula: d=Σn i di / Σn i , where n i is the particle diameter d i is the number of.

[0066] -3D structure- Porous carbon black with a well-developed three-dimensional structure is preferred as a catalyst support for fuel cells. When a catalyst layer is formed using this three-dimensional structure, the catalyst layer becomes highly porous with voids, which increases the diffusion rate of oxidizing gases. As the physical property values ​​that reflect the three-dimensional structure, for example, DBP oil absorption and mercury intrusion distribution by mercury porosimetry method can be applied.

[0067] The DBP oil absorption is an industrial index of a typical colloidal physical property of carbon black, and is a value listed in a catalog. In defining the physical properties in this disclosure, the value listed in the physical property table of the carbon black manufacturer is used. Specifically, the DBP oil absorption value is preferably 80 mL / 100 g or more, more preferably 100 mL / 100 g, and even more preferably 120 mL / 100 g. Since the specific gravity of raw carbon black is approximately 1.8 g / mL, if we consider the DBP oil absorption to correspond to the voids in the catalyst layer, a DBP oil absorption of 80 mL / 100 g corresponds to voids 1.4 times the volume of the raw carbon black. If the DBP oil absorption is less than 80 mL / 100 g, the development of the three-dimensional structure is too small, resulting in a decrease in high-load performance. On the other hand, the upper limit of DBP oil absorption is 180 mL / 100 g, which is the theoretical upper limit for manufacturing. The DBP oil absorption indicates the amount of dibutyl phthalate (DBP) absorbed by 100 g of carbon black, and is a value defined in ASTM (American Standard Test Method) D2414-6TT.

[0068] The evaluation of the three-dimensional structure by mercury porosimetry is carried out by converting the hydrostatic pressure applied to mercury into pore diameters when assuming a cylinder using the surface tension of mercury against the raw carbon black, and then obtaining a distribution of the integrated values ​​of the volumes of pores larger than the pore diameter on the vertical axis, with the pore diameter on the horizontal axis. Raw material carbon black with a three-dimensional structure absorbs mercury in proportion to the pore volume at an injection relative pressure equivalent to the pore size caused by the three-dimensional structure, so the three-dimensional structure can be quantitatively evaluated from the pore size distribution of the amount of mercury absorbed. Specifically, the increase in the amount of mercury absorbed when the mercury pressure is increased from 10 MPa (corresponding to pores of approximately 10 nm) to 100 MPa (corresponding to pores of approximately 100 nm) is preferably 0.5 to 1.5 mL / g, taking into account the DBP oil absorption suitable for the pores in the catalyst layer described above. If the increase in the amount of mercury is less than 0.5 mL / g, the development of the three-dimensional structure is too small, resulting in a decrease in high-load characteristics. On the other hand, a mercury increase of 1.5 mL / g is the theoretical upper limit for manufacturing.

[0069] -Granulation state- There are four Japanese Industrial Standards related to the granulation state of raw carbon black: JIS K 6219-1 Part 1: Determination of fine powder amount JIS K 6219-2 Part 2: Determination of bulk density JIS K 6219-3 Part 3: Determination of hardness of granulated particles JIS K 6219-4 Part 4: Determination of granule size distribution

[0070] In Japan, raw carbon black is primarily granulated using a wet process using water. The granules are vigorously mixed with water in a drum-type granulator containing a rotating shaft with spirally embedded pins, followed by drying with hot air at approximately several hundred degrees Celsius. The size, distribution, hardness, and bulk density of the pellets are adjusted by the peripheral speed of the pins, the proportion of water added to the carbon black, and the method of addition. While binders other than water, typically lignin, are used to improve dispersibility, it is preferable to use no binders or to add only small amounts of such binders. Regarding size, pellets larger than 1000 μm tend to have a relatively low internal density and are easily dispersed, so particles larger than 1000 μm are preferred. The pellet hardness is 40 g / particle or less, preferably 30 g / particle or less, and more preferably 20 g / particle or less.

[0071] (Activation process) The activation step is a step of activating raw carbon black to make it porous. The mechanism of activation of raw carbon black is thought to be as follows. By exposing raw carbon black to an activation gas such as water vapor (H2O) or CO2 and maintaining it at 800-1100°C, the carbon atoms that make up the raw carbon black are removed as CO. This reaction optimizes the reaction rate, selectively oxidizing and consuming the edges of the easily combustible condensed polycyclic aromatic rings in the nanometer-sized crystallites that make up the raw carbon black. As a result, gaps form between the crystallites, and the consumption of the crystallites continues inward. This results in the formation of porous carbon black. This is the process by which carbon black is activated to become porous.

[0072] Increasing the activation temperature increases the reaction rate, accelerating combustion near the surface where it comes into contact with a high concentration of activation gas, while the concentration of activation gas diffusing into the interior becomes even lower, slowing internal combustion. To develop pores inside without changing the surface condition, it is necessary to control the reaction rate appropriately. Steam and CO2 are the most suitable activation gases, as they allow the reaction rate to be controlled over a wide range by changing the temperature. The application of oxygen activation has not been commercialized for the following reasons: The oxidation reaction of raw carbon black using water vapor and CO2 is an endothermic reaction, meaning that the reaction will not proceed unless heat is added, and it can be controlled by the amount of heat supplied, making it easy to scale up. In contrast, the oxidation reaction of raw carbon black using oxygen is an exothermic reaction, and if the heat generated is greater than the heat removed, the temperature at the reaction site will rise monotonically, making the reaction difficult to control. This phenomenon accelerates with increasing size, so oxidation with oxygen is not suitable for mass production, and activation using water vapor or CO2 as the activation gas is more suitable.

[0073] As long as a manufacturing process in which this activation reaction proceeds can be realized, there are no restrictions on the activation device. To efficiently promote activation, it is desirable to increase the concentration of activation gas on the surface of the raw carbon black pellets. To achieve this, it is desirable to reduce the thickness of the boundary film of oxidizing gas formed near the surface of the raw carbon black pellets, and it is effective to increase the relative velocity of the activation gas with respect to the raw carbon black pellets. A rotary kiln or fluidized bed, which are generally used in industrial production, is preferred because it can increase the uniformity of the activation gas within the furnace. Because it can increase the relative velocity of the activation gas with respect to the raw carbon black pellets, a fluidized bed is an excellent device in terms of gas utilization rate and reaction rate, and is particularly preferred.

[0074] The specific activation conditions are to control the temperature according to the reaction strength of the activation gas, which is preferably water vapor or CO2. When water vapor is used as the activation gas, the temperature is preferably 750°C to 900°C, and when CO2 is used as the activation gas, the temperature is preferably 800°C to 950°C. Requirement (A) (BET surface area 800~1400m 2 To obtain porous carbon black that satisfies the above requirement, the mass reduction rate of the porous raw carbon black due to activation is, for example, 50 to 85% by mass, and preferably 60 to 80% by mass. The treatment time required to reach such a mass reduction rate is, for example, 5 to 100 hours, preferably 10 to 80 hours, and more preferably 20 to 80 hours. Under activation conditions where the time required to reach a mass loss rate of 50% by mass is shorter than 5 hours, differences occur, such as a smaller BET surface area or a larger volume of pores 10 nm or larger in the pore size distribution obtained by BJH analysis of the nitrogen gas adsorption isotherm, compared to, for example, a case where the time required to reach the same mass loss rate is 20 hours. These differences in BET surface area and pore size distribution are due to the fact that if the reaction rate is too high, the surface combustion of the raw carbon black is relatively large compared to the internal combustion that forms internal pores, and part of the mass loss is consumed by surface combustion, preventing the BET specific surface area from increasing. Furthermore, large irregularities of 10 nm or larger are formed due to surface combustion (pores formed when depressions at the bonds between primary particles develop due to surface combustion). In other words, to suppress surface combustion, it is preferable to lower the activation temperature and lengthen the activation time. On the other hand, activation for a long time, such as when the time required for the mass reduction rate to reach 50% by mass exceeds 100 hours, is not preferable because the activation rate is too slow, causing surface combustion to prevail over internal combustion and inhibiting the development of pores.

[0075] It is also preferable to carry out activation under an elevated activation gas pressure. Because the activation gas concentration is high, the oxidation reaction rate increases almost in proportion to the concentration, and the activation time can be shortened without changing the pore development, i.e., the BET surface area and pore size distribution, or the surface combustion rate. The activation time can be shortened in proportion to the pressure up to several atmospheres. At pressures above 6 atmospheres, the effect of the substantial pressure increase is difficult to see, and a pressure of 6 atmospheres or less is preferred. The activation time when activated under pressurized conditions is, for example, 3 to 50 hours, preferably 5 to 30 hours, and more preferably 5 to 20 hours. The upper and lower limits of the activation time are determined to avoid the same phenomenon as when activated under normal pressure.

[0076] By the above activation step, pores are formed inside the raw material carbon black, and porous carbon black that satisfies requirement (A) can be produced. In the process of increasing the crystallinity in the heat treatment process, the texture and crystalline structure of the porous raw carbon black changes toward a more stable graphite structure, and the pores, which can be considered defects, change in the direction of collapse. Therefore, the pore structure of the porous raw carbon black obtained in the activation process must be made more developed than the final desired pore structure so that a desirable pore structure is maintained even after the pores are collapsed in the heat treatment process. In other words, in order to satisfy requirement (A) after the activation treatment process, the BET surface area of ​​the porous raw carbon black obtained in the activation process must be at least 400 m, which is the lower limit of requirement (A). 2 / g or more is preferable.

[0077] (Heat treatment process) The heat treatment step is a step in which the porous raw carbon black obtained in the activation step is heat-treated. In the operating environment of a fuel cell, the catalyst support is exposed to a noble potential of 1 V or more. Because ionomers have sulfonic acid groups, catalyst supports coated with ionomers are placed in a noble potential of 1 V or more and in a strongly acidic environment. When porous carbon black is used in such an environment, thermodynamic stability cannot be expected, so the general approach is to increase its crystallinity as much as possible to rapidly avoid oxidative consumption.

[0078] To enhance the crystallinity of porous carbon black, it is common to heat treat it in an inert gas atmosphere or a reducing atmosphere. In the heat treatment step, for example, the porous raw carbon black obtained in the activation step is subjected to a heat treatment step (i.e., graphitization step) at 1400°C to 1900°C under an inert gas atmosphere at normal pressure (i.e., 1 atmosphere) for 10 minutes to 10 hours. In order to obtain a porous carbon material (that is, porous activated carbon black) suitable for the present disclosure, it is important to select an optimum heat treatment temperature according to the primary particle size of the raw material carbon black. Specifically, if the primary particle size of the raw material carbon black is 60 nm or less, it is difficult to improve the crystallinity, so the upper limit of the heat treatment temperature is preferably set to 1900° C. On the other hand, if the primary particle size of the raw material carbon black is more than 60 nm, it is easy to improve the crystallinity, so the upper limit of the heat treatment temperature is preferably set to 1800° C.

[0079] In the heat treatment step, graphitization of the porous raw carbon black can increase the crystallinity of the porous raw carbon black. More specifically, by subjecting the porous raw carbon black having a BET specific surface area that has been activated under the above-mentioned strong activation conditions to a heat treatment under the above-mentioned conditions, the crystallinity of the porous raw carbon black can be increased while maintaining the pores. In other words, it is possible to produce porous carbon black that satisfies requirements (A) and (C).

[0080] Furthermore, by subjecting porous raw carbon black having a BET specific surface area that has been activated under strong activation conditions to heat treatment under the above conditions, it is possible to increase the crystallinity of the porous raw carbon black while maintaining the mesopores. In other words, it is possible to produce porous carbon black that satisfies requirement (D) in addition to requirement (C).

[0081] The heat treatment step is not particularly limited as long as it can heat the porous raw carbon black under the above conditions. Examples of the heating method include resistance heating, microwave heating, high-frequency heating, and furnace-type heating methods. The furnace type is not limited, and may be a graphitization furnace, batch furnace, tunnel furnace, or the like, as long as it can achieve atmospheric pressure and an inert gas atmosphere.

[0082] (Ozone treatment process) The ozone treatment step is an ozone treatment step in which the heat-treated porous raw carbon black obtained in the heat treatment step is oxidized under a flow of ozone gas. Ozone (O3) has an oxidizing power second only to fluorine, so it can be used to oxidize raw carbon black. The blackness of raw carbon black can be increased by adjusting the amount of oxygen-containing functional groups, so it is used industrially in the production of colored carbon black. Taking advantage of its strong oxidizing power, ozone was applied to the selective oxidation of the surface of raw carbon black. Specifically, the aggregates, which are the basic particles of raw carbon black, are agglomerated to form pellets, which are then activated and heat-treated in pellet form to impart a pore structure and enhance crystallinity, resulting in heat-treated porous raw carbon black. However, during heat treatment, the porous raw carbon black is exposed to high temperatures of over 1400°C in an inert gas atmosphere while in an agglomerated state, causing the aggregates to chemically bond together, making them difficult to disintegrate even with mechanical action or ultrasonic waves in a medium. When heat-treated porous raw carbon black is exposed to ozone, the carbon black surface is oxidized and consumed as CO2. This consumption burns off the aforementioned bonding sites, making it easier to disintegrate into aggregates.

[0083] For ozone treatment, any device capable of generating 10 mg / hour or more of ozone can be used, and there are no limitations on the ozone generation mechanism or device structure. To increase the ozone generation rate, pure oxygen is usually used as the input gas. This is because inputting air contains a low amount of oxygen, which is the ozone source, and the amount of ozone generated decreases accordingly. Because ozone is unstable and self-decomposes over time, it is best to contact the heat-treated porous raw carbon black with a gas containing ozone in a steady flow. To increase the reaction rate, ozone gas and the heat-treated porous raw carbon black may also be contacted in a heated state.

[0084] The appropriate range of ozone treatment conditions is determined by two factors: ozone treatment temperature and ozone treatment time. Only when these two factors are simultaneously satisfied can a material suitable for the present disclosure be prepared. For example, the appropriate range of ozone treatment temperature is room temperature (25° C.) to 50° C. As the ozone treatment temperature increases, the rate of ozone self-decomposition also increases, so 50° C. is the practical upper limit for oxidizing the heat-treated porous raw carbon black. If the ozone treatment conditions are optimized according to the primary particle size of the raw material carbon black, it is possible to obtain a desirable porous carbon material (that is, porous activated carbon black). When the primary particle diameter of raw carbon black is 60 nm or less, pores tend to develop, so even if the ozone treatment time is extended, there is little oxidation of the surface of the heat-treated porous raw carbon black. Therefore, it is easy to set a long upper limit for the heat treatment time. Specifically, it is appropriate to set the upper limit for the ozone treatment time to 8 hours. On the other hand, when the primary particle size of the raw material carbon black exceeds 60 nm, pores are less likely to develop, so the ozone treatment time is preferably shorter than when the primary particle size of the raw material carbon black is 60 nm or less. Specifically, the upper limit of the ozone treatment time is appropriately set to 5 hours. If the ozone treatment time is shorter than one hour, the amount of heat generated is large, and the heat-generating site is selectively oxidized, preventing a uniform reaction, which is inappropriate. If the ozone treatment time exceeds 8 hours, oxidation inside the pores will progress and the pore structure will change, which is not preferable. The mass loss rate in the ozone treatment is preferably 0.05 to 5.0% by mass. Specifically, when the primary particle diameter of the raw carbon black is 60 nm or less, the mass loss rate in the ozone treatment is preferably 0.05 to 5.0% by mass. On the other hand, when the primary particle diameter of the raw carbon black is more than 60 nm, the mass loss rate in the ozone treatment is preferably 0.05 to 3.0% by mass.

[0085] <Catalyst layer for polymer electrolyte fuel cell and polymer electrolyte fuel cell> The polymer electrolyte fuel cell will now be described together with the catalyst layer for a polymer electrolyte fuel cell of the present disclosure. The carbon material of 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 general configuration of a fuel cell of 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.

[0086] Separator 110 is an anode-side separator that introduces a reducing gas such as hydrogen into gas diffusion layer 130. Separator 120 is a cathode-side separator that introduces an oxidizing gas such as oxygen gas or air into the gas diffusion condensation layer. The types of separators 110 and 120 are not particularly limited, and may be any separator used in conventional fuel cells (e.g., solid polymer fuel cells).

[0087] 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.

[0088] The catalyst layer 150 is a so-called anode. An oxidation reaction of the reducing gas occurs in the catalyst layer 150, producing protons and electrons. For example, when the reducing gas becomes hydrogen gas, the following oxidation reaction occurs. H2→2H + +2e - (E0=0V)

[0089] Protons produced by the oxidation reaction pass through the catalyst layer 150 and the electrolyte membrane 170 to reach the catalyst layer 160. Electrons produced by the oxidation reaction pass through the catalyst layer 150, the gas diffusion layer 130, and the separator 110 to reach the external circuit. After performing work (generating electricity) in the external circuit, the electrons are introduced into the separator 120. The electrons then pass through the separator 120 and the gas diffusion layer 140 to reach the catalyst layer 160.

[0090] 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 that of the catalyst layer 160.

[0091] 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. O2+4H + +4e - →2H2O (E0=1.23V)

[0092] 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.

[0093] 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 power generation characteristics (particularly high load characteristics) and durability of the catalyst layer 160. This can also improve the power generation characteristics (particularly high load characteristics) and durability of the polymer electrolyte fuel cell 100.

[0094] The catalyst loading rate in the catalyst layer 160 is not particularly limited, and is preferably 30% by mass or more and less than 80% by mass. A catalyst loading rate within this range further improves power generation characteristics (particularly high load characteristics) and durability. Here, the catalyst loading rate is expressed as the mass % 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 make the polymer electrolyte fuel cell 100 practical. 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.

[0095] 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, the pore network and the electrolyte material network can coexist, resulting in improved power generation characteristics (particularly high-load characteristics) and durability. 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 increase. If the mass ratio I / C is 5.0 or more, the pore network may be disrupted by the electrolyte material. In either case, the power generation characteristics (particularly high-load characteristics) and durability may be reduced.

[0096] Furthermore, the thickness of the catalyst layer 160 is not particularly limited, but 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 active. In other words, the catalyst utilization rate may decrease.

[0097] The electrolyte membrane 170 is made of an electrolyte material having proton conductivity. 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 into which phosphate groups, sulfonic acid groups, etc. are introduced. Specific examples include perfluorosulfonic acid polymers and polymers into which benzenesulfonic acid, etc., are introduced. 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 of room temperature (25°C) to 150°C.

[0098] <Method of 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 is made of 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. [Example]

[0099] 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.

[0100] <Measuring methods for each parameter> (Nitrogen adsorption / desorption isotherm (BET specific surface area) measurement) Approximately 30 mg of a sample of the carbon material for catalyst support was weighed out and vacuum dried for 2 hours at 120° C. The sample was then set in an automatic specific surface area measuring device (MicrotrackBell, BELSORP MAX) and the nitrogen adsorption / desorption isotherm was measured at the liquid nitrogen temperature (approximately 77 K) using nitrogen gas as the adsorbate. The BET specific surface area was calculated by BET analysis of the nitrogen adsorption isotherm in the relative pressure P / P range of 0.05 to 0.15. The value was calculated.

[0101] (Measurement of particle size distribution by laser light scattering method) A 10 mg sample of the carbon material for catalyst support was weighed into a sample bottle, and 1 mL of a 10 mass % Liponox solution (aqueous solution of Liponox CN, a polyoxyalkylene phenyl ether surfactant manufactured by Lion Corporation) was added. The mixture was then dispersed by irradiating with ultrasound for 10 minutes using an ultrasonic disperser. Next, the 10 mass % Liponox solution was added so that the transmittance fell within a predetermined range, and the result was measured using a measuring device (LA-920 manufactured by Horiba, Ltd.). The particle size distribution of the cumulative amount of passing particles from small to large particles obtained by volumetric particle size measurement was obtained by the measurement.Then, the particle size distribution of the cumulative amount of passing particles was used to calculate the following particle sizes (see Figure 2). Common logarithm of particle size D5 (μm) when the cumulative amount of passing particles is 5% Common logarithm of particle diameter when the cumulative amount of passing particles is 95% D 95 (μm) Common logarithm of particle diameter when the cumulative amount of passing particles is 50% D 50 (μm) Common logarithm of mode diameter D mode (Here, the mode diameter is the particle diameter corresponding to the peak value of the particle diameter distribution of the accumulated amount of passing particles.)

[0102] Then, based on these particle diameters, the difference Δ=D 95 -D5, (D 50 -D mode ) / D 50 asked for.

[0103] (Raman spectroscopy and ΔG evaluation) Approximately 30 mg of a sample of the carbon material for catalyst support was weighed and taken, and the Raman spectrum was measured using a laser Raman spectrophotometer (manufactured by JASCO Corporation, NRS-3100 model). From the Raman spectrum obtained under the following measurement conditions, the band at 1560 cm, known as the G band, was detected. -1 ~1620cm -1 The peak in the range of 1 / 2 the peak intensity is extracted, and the peak spectrum width (△G, cm) at half the peak intensity of this peak is calculated. -1 The software attached to the device was used to calculate ΔG. -Measurement conditions- Excitation laser: 532 nm, laser power: 10 mW (sample irradiation power: 1.1 mW), microscope configuration: backscattering, objective lens: ×100 magnification, spot diameter: 1 μm, exposure time: 30 sec, observation wavenumber: 2000 cm-1 to 300 cm -1 , Number of times accumulated: 6 times

[0104] <Experimental Example> (raw carbon black) As raw carbon black, Niteron #300IH, Niteron #200, Niteron #10, and Niteron #SH manufactured by Nippon Steel Carbon Corporation, and carbon black and GFY manufactured by Tokai Carbon Co., Ltd. were prepared. These raw carbon blacks were subjected to the activation process, heat treatment process, and ozone treatment process described below.

[0105] On the other hand, two types of porous carbon black, Ketjenblack EC600JD and EC300J, manufactured by Lion Corporation, were prepared as raw carbon black. Because they were porous, they did not require any activation treatment. These raw carbon blacks were subjected to a heat treatment process and an ozone treatment process.

[0106] Table 1 below shows the primary particle size (arithmetic mean particle size) and DBP oil absorption values ​​of the raw carbon black cited from Carbon Black Yearbook No. 72 (2022), compiled by the Carbon Black Association, and listed on the Ketjen Black product website.

[0107] [Table 1]

[0108] (Activation treatment process) A reaction tube was prepared by fusing a quartz filter as a dispersion plate inside a quartz tube with an outer diameter of 35 mm. Quartz wool was placed on the dispersion plate to a height of about 1 cm, and 5 g to 15 g of granulated raw material carbon black was placed on top of that. The reaction tube was then set in a vertical electric furnace normally used at 1100°C. Before heating, argon gas was flowed from bottom to top of the reaction tube, replacing the interior of the reaction tube with argon gas. The temperature was then raised at a rate of 10°C / min. The reaction tube was heated to 850-950°C, and once the desired temperature was reached, CO2 gas was switched on. The flow rate was adjusted so that the linear velocity was 1-2 cm / s at the furnace temperature. After the desired treatment time, the reaction tube was removed from the furnace, and the gas was simultaneously switched to argon gas and allowed to cool. After confirming that the reaction tube had cooled to near room temperature, the porous carbon black raw material was removed and its mass was measured. The mass loss ratio of the yield to the charged mass (charged mass / recovered mass) was calculated. The activation temperature and activation time were adjusted as shown in Table 2 to achieve a mass loss ratio in the range of 55-80% by mass.

[0109] (Heat treatment process) The heating furnace used was a so-called graphitization furnace, which uses graphite as a heating element. The porous raw carbon black obtained in the activation process was placed in a graphite crucible with a volume of approximately 100 cc, and after the pressure was reduced and the atmosphere was replaced with argon gas, the temperature was raised at 10°C per minute at an argon flow rate sufficient to replace the furnace volume in several tens of minutes. After holding at the specified temperature for a certain period of time, the material was allowed to cool to near room temperature and then removed. The holding time at the heat treatment temperature was variable, and the conditions are shown in Table 2.

[0110] (Ozone treatment process) Pure oxygen was used as the input gas for a research ozone generator manufactured by Kotohira Kogyo Co., Ltd. The ozone gas generation principle of this device is a so-called discharge method, where the ozone concentration is controlled by the voltage and current between the electrodes and the gas flow rate. A mixture of ozone and oxygen was the output gas from the generator. The electrode voltage was fixed, while the input oxygen gas flow rate was variable, at 2 L / min. The larger the surface area of ​​porous raw carbon black, the more easily it is oxidized by ozone. Furthermore, the more crystallinity is achieved by heat treatment, the less susceptible it is to oxidation. Because ozone oxidation of porous raw carbon black is an exothermic reaction, a large reaction volume can trap heat and cause localized temperature increases, resulting in ignition. Therefore, in this experiment, the ozone was diluted by mixing the output gas from the ozone generator with argon gas to a level that would prevent the carbon from igniting due to the reaction heat. The amount of gas sent to the reaction tube was also controlled. The reaction volume of the ozone treatment was controlled by the contact time with the output gas or by placing the reaction tube in an electric furnace and heating it.

[0111] The specific reaction apparatus used was a vertical quartz reaction tube of the same shape as that used for activation, with a filter made of fused quartz beads attached inside the tube as a dispersion plate. Fine-fiber quartz wool was optionally laid on top of the dispersion plate, and the heat-treated porous carbon black raw material obtained in the heat treatment process was placed on top of that. The reaction gas was flowed from bottom to top, with the flow rate increased to a level sufficient to prevent powder from scattering outside the system and adjusted to a linear velocity of 0.5–2 mL / sec to minimize reaction unevenness. The reaction volume was determined by mass change. At the beginning of the reaction, mass increased by up to 0.5% due to the addition of oxygen functional groups, followed by a mass loss. The pore structure after ozone oxidation was investigated using nitrogen gas adsorption isotherms. The isotherms before and after treatment were nearly identical, confirming that the surface had burned off and the pore size distribution due to internal combustion had not changed due to ozone oxidation. Table 2 shows the reaction temperature (controlled by the temperature of the electric furnace) and reaction time, which are control factors in the ozone treatment process.

[0112] Through the above steps, a carbon material for a catalyst support (porous activated carbon black) was obtained for each example.

[0113] <Fabrication of Membrane Electrode Assembly (MEA)> (Fabrication of Catalyst) Add the carbon material for catalyst support (porous activated carbon black) of each example to an ethanol / water mixed solvent, and treat it with an ultrasonic homogenizer for 2 minutes to disperse it. Then add a predetermined amount of a nitric acid solution of dinitrodiammine platinum complex, adjust the platinum loading rate to 40% by mass, keep the temperature a few degrees lower than the boiling point, and stir in an oil bath for 15 hours. After the treatment, filter it, disperse it again in distilled water, re-filter it, and treat it by vacuum drying at 90 °C for 5 hours to obtain a catalyst.

[0114] (Fabrication of Ink) Dilute the ionomer solution manufactured by Fujifilm Wako Pure Chemical Corporation with ethanol to adjust the solid content concentration to 10% by mass, then drop it into an ethanol solution in which the catalyst has been previously dispersed, further disperse it with an ultrasonic homogenizer, and stir it with 1 mmφ glass beads for 10 - 15 hours. Thus, an ink for forming a catalyst layer was obtained.

[0115] (Fabrication of MEA) Uniformly apply the above ink on a Teflon (registered trademark) sheet with a sprayer, dry it with a 60 °C air circulation dryer, and prepare a decal with a formed catalyst layer. Cut out electrodes of a predetermined 36 mm size from the decal. Use the two cut sheets of the same size as the positive electrode and the negative electrode, align the positive electrode and the negative electrode on both sides of the Nafion membrane, and thermally fuse them. Thus, an MEA was obtained.

[0116] (Battery Evaluation) (Evaluation of Power Generation Characteristics (High Load Characteristics)) Regarding the MEAs fabricated using the carbon materials for catalyst support (porous activated carbon black) of each example, each was incorporated into a cell, set in a fuel cell measurement device, and the performance evaluation of the fuel cell was carried out according to the following procedure.

[0117] The oxidizing gas was supplied at a back pressure of 0.04 MPa, with air supplied to the cathode side and pure hydrogen supplied to the anode side, with the pressure adjusted by a back pressure valve installed downstream of the cell so that the utilization rates were 40% and 70%, respectively. The cell temperature was set to 80°C, and the oxidizing gas supplied was bubbled with distilled water kept at 60°C in a humidifier at both the cathode and anode, and humidified gas at 60°C was supplied to the 80°C cell to evaluate power generation.

[0118] Under these settings, the load was gradually increased while supplying oxidizing gas to the cell, and the current density at an output voltage of 0.3 V was measured as mA / cm. 2 The results were measured in units of 1000 kJ / s and evaluated according to the following pass / fail ranking criteria. The results are shown in Table 2. [Passing rank] A: Current density is 1400mA / cm at a cell voltage of 0.3V 2 That which is more than that. B: Current density at cell voltage 0.3 V is 1350 mA / cm 2 That which is more than that. C: Current density is 1300mA / cm at a cell voltage of 0.3V 2 That which is more than that. [Failure rank] D: Current density at cell voltage 0.3 V is 1300 mA / cm 2 Something that is less than.

[0119] (Durability evaluation) The cell was left with the anode in place, and argon gas was passed through the cathode under the same humidified conditions as above. One cycle consisted of a cycle of setting the cell voltage to 1.0 V and holding it for 4 seconds, followed by a cycle of setting the cell voltage to 1.3 V and holding it for 4 seconds (repeated square-wave voltage fluctuation). After 4,000 cycles of this square-wave voltage fluctuation cycle, durability was investigated in the same manner as in the evaluation of power generation characteristics described above. Evaluation was conducted using the following pass / fail ranking criteria. The results are shown in Table 2. [Passing rank] A: Current density is 1100mA / cm at a cell voltage of 0.3V 2 That which is more than that. B: Current density is 1000mA / cm at a cell voltage of 0.3V 2 That which is more than that. C: Current density at cell voltage 0.3 V is 950 mA / cm 2 That which is more than that. [Failure rank] D: Current density at cell voltage 0.3 V is 950 mA / cm 2 Something that is less than.

[0120] [Table 2-1]

[0121] [Table 2-2]

[0122] [Table 2-3]

[0123] [Table 2-4]

[0124] The above results will be explained below.

[0125] <Experimental Example #10 Series> (#10-1~5) Nitelon #10 was used as the raw carbon black, and the carbon black was activated at 900°C for 6 hours (except for #10-1, which was activated at 900°C for 8 hours), and five samples were prepared by varying the subsequent heat treatment temperature. These five samples were not ozone treated. BET surface area, Δ=D 95 There was no sample that satisfied both -D5 and ΔG simultaneously, and no sample that passed both power generation characteristics (high load characteristics) and durability simultaneously.

[0126] (#10-6~10 and #10-10A~10B) Seven samples were prepared using the same raw carbon black as #10-1 to #10-5, but with activation conditions of 900°C for 7 hours, a fixed heat treatment temperature of 1700°C for 1 hour, and varying ozone treatment conditions. Their power generation characteristics and durability were then evaluated. Ozone treatment was performed at room temperature (25°C) and the treatment time was varied. Five types of samples were prepared, including one in which combustion did not progress and the mass increased due to the addition of oxygen, and one in which the mass loss due to combustion was less than 5% by mass. For #10-6 without ozone treatment, Δ=D 95 The other five samples did not meet the BET specific surface area, Δ=D, of the present disclosure. 95 -D5 and ΔG specifications are met, and both power generation characteristics (high load characteristics) and durability are met at the same time.

[0127] (10-10C~10D and #10-11~15) The raw carbon black used was the same as #10-1 to #10-1, but the activation conditions were lowered to 850°C to slow the reaction rate and the treatment time was extended to 25 hours. This resulted in the BET specific surface area shown in Table 2. Seven samples were produced by heat treatment at 1200°C, 1400°C, or 1700°C, and by increasing the ozone treatment temperature to 30°C, 50°C, or 70°C for different treatment times. Their power generation characteristics (high-load characteristics) and durability were then evaluated. As a result, #10-11 to #14, which satisfy the physical properties of the present disclosure, exhibited excellent power generation characteristics (high-load characteristics) and durability.

[0128] <Experimental Example #SH Series> (#SH-1~4) Nitelon #SH was used as the raw carbon black, and the carbon black was activated at 850°C for 40 hours to make it porous, followed by varying the heat treatment temperature. The ozone treatment time was adjusted so that the mass loss rate was 0.7 to 1.5% by mass at room temperature. Four samples were prepared in this manner. Their power generation characteristics (high load characteristics) and durability were evaluated. As a result, #SH-1 and #SH-2, which met the physical properties of the present disclosure, demonstrated excellent power generation characteristics and durability.

[0129] <Experimental Example #200 Series> (#200-1~5 and 200-1A~1C) Nitelon #200 was used as the raw carbon black, and was activated at 850°C for 25 hours to make it porous, followed by varying the heat treatment temperature. The ozone treatment was performed at room temperature (25°C), and the higher the heat treatment temperature, the longer the treatment time. The treatment time was adjusted so that the mass loss rate was 0.8 to 5.2% by mass. Eight samples were prepared in this manner. Their power generation characteristics (high-load characteristics) and durability were evaluated. As a result, #200-1B to #200-1C and #200-2 to #200-5, which satisfy the physical properties of the present disclosure, exhibited excellent power generation characteristics (high-load characteristics) and durability.

[0130] <Experimental example #300IHs series> (#300-1~5) Nitelon #300IH was used as the raw carbon black, and the carbon black was activated at 850°C for 22 hours to make it porous, and the subsequent heat treatment temperature was varied. The ozone treatment was performed at room temperature (25°C), and the higher the heat treatment temperature, the longer the treatment time was. The treatment time was adjusted so that the mass loss rate was 1.2 to 3.6 mass%. Five samples were produced in this manner. Then, their power generation characteristics (high load characteristics) and durability were evaluated. As a result, #300-2 to #300-5, which satisfied the physical properties of the present disclosure, showed excellent power generation characteristics and durability.

[0131] <Experimental example GFY series> (GFY-1~8) GFY was used as the raw carbon black and was activated at 850°C for 50 to 110 hours to make it porous. The subsequent heat treatment temperature was varied. Ozone treatment was performed at room temperature (25°C) or 40°C. The higher the heat treatment temperature, the longer the treatment time. The treatment time was adjusted so that the mass loss rate was 0.95 to 3.9% by mass. Eight samples were prepared in this manner. Their power generation characteristics (high-load characteristics) and durability were evaluated. As a result, GFY-1 to GFY-3 and GFY-6 to GFY-7, which satisfied the physical properties specified in the present disclosure, exhibited excellent power generation characteristics (high-load characteristics) and durability. In particular, GFY-2 to GFY-3 exhibited the most excellent durability among the examples. #SH-1 and #SH-2 exhibited the next-best durability. These results for GFY and #SH revealed that using raw carbon black with a large primary particle size, specifically a primary particle size exceeding 60 nm, is effective in improving durability.

[0132] <Experimental example EC series> (EC-1~4) Ketjenblack EC300J and EC600JD, which were already porous, were used as raw carbon black. Because they already had sufficient porosity, they were heat-treated at 1500°C without activation, and then the temperature was varied. The ozone treatment was performed at room temperature, and the higher the heat treatment temperature, the longer the treatment time. The treatment time was adjusted so that the mass loss rate was 0.9 to 2.1% by mass. Four samples were prepared in this manner. Their power generation characteristics (high-load characteristics) and durability were evaluated. As a result, because all samples were ozone-treated, they met the physical properties of the present disclosure. Although their performance was slightly inferior, they exhibited superior power generation characteristics (high-load characteristics) and durability compared to the comparative examples. The two types of raw carbon black used in the EC series are pellets that are so hard that they cannot be easily crushed by hand, and are presumed to have undergone a different granulation process than the other raw carbon blacks.The hardness of these pellets means that they do not disperse sufficiently even after surface combustion using ozone treatment, which is presumably why they are inferior in power generation characteristics (high load characteristics) and durability.

[0133] These experimental examples demonstrated that a carbon material for a catalyst support (porous activated carbon black) that satisfies the specifications of the present disclosure and is produced by a preferred production method has both excellent power generation characteristics (high load characteristics) and durability.

[0134] The symbols are explained as follows: 100 Solid polymer fuel cell 110, 120 separator 130, 140 Gas diffusion layer 150, 160 catalyst layer 170 Electrolyte membrane

[0135] The disclosure of Japanese Patent Application No. 2023-108952 is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or 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), (B') and (C): (A) BET surface area (m) measured by nitrogen gas adsorption ２ / g) is 400 or more and 1200 or less. (B) In the particle size distribution of the cumulative amount of passing particles from small particles to large particles obtained by the volume-based particle size by the laser light scattering method, when the total cumulative amount is set to 100%, the common logarithm of the particle size when the cumulative amount of passing particles is 5% and 95%, respectively, is D ５ (μm), D ９５ (μm), the difference Δ=D ９５ -D ５ is 0.35 or more and 2.00 or less. (B') In the particle size distribution of the cumulative amount of particles passing through from small particles to large particles obtained by a volume-based particle size measurement using a laser light scattering method, when the total cumulative amount is set to 100% and the common logarithm of the particle size when the cumulative amount of particles passing through is 50% is set to D50 (μm), D50 (μm) is -1.70 or more and -1.00 or less. (C) In the Raman spectrum obtained by Raman spectroscopy, －１ ~1620cm －１ The full width at half maximum of the G band ΔG (cm －１ ) is between 72 and 90.

2. The carbon material for a catalyst support of a polymer electrolyte fuel cell according to claim 1, further satisfying the following requirement (D): (D) In ​​the particle size distribution of the passing accumulated amount, the common logarithm of the particle size when the passing accumulated amount is 50% is D ５０ (μm), the common logarithm of the mode diameter is D ｍｏｄｅ (μm), (D ５０ -D ｍｏｄｅ ) / D ５０ is greater than or equal to -0.16 and less than or equal to 0.

20.

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

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