Carbon material for catalyst carrier in solid polymer fuel cell, catalyst layer for solid polymer 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

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

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

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

[0003] A fuel gas such as hydrogen is introduced into the separator on the anode side. After diffusing the fuel into the gas diffusion layer on the anode side, it is introduced into the anode. The anode contains a catalyst component, a catalyst carrier 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 carrier is often made of a porous carbon material. An oxidation reaction of the fuel gas occurs on the fuel cell catalyst, generating protons and electrons. For example, when the fuel gas becomes hydrogen gas, the following oxidation reaction occurs: H ２ →2H ＋ +2e － (E ０ = 0 V)

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

[0005] The solid polymer electrolyte membrane is made of an electrolyte material with proton conductivity. The solid polymer electrolyte membrane introduces protons generated in the above oxidation reaction to the cathode. An oxidizing gas such as oxygen gas or air is introduced into the separator on the cathode side. The gas diffusion layer on the cathode side diffuses the oxidizing gas, and then introduces it into the cathode. The cathode includes a fuel cell catalyst, a catalyst support that supports the fuel cell catalyst, and an electrolyte material with proton conductivity. 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: O ２ +4H ＋ +4e － →2H ２ O (E ０ = 1.23 V)

[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 proposes "a method for producing high surface area graphitized carbon, the method comprising, in any order, a step of graphitizing a starting carbon material, and optionally carbon black, and a step of increasing the surface area to produce high surface area graphitized carbon, wherein the step of increasing the surface area is carried out 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 a catalyst carrier used in a catalyst carrier of a polymer electrolyte fuel cell, which has a three-dimensionally branched dendritic structure, and is characterized by simultaneously satisfying the following (1) and (2)." (1) In particle size distribution measurement using a laser diffraction / scattering particle size distribution analyzer, the DL / DH ratio is 1.5 or greater, where DL is the cumulative distribution [%] of particles with a particle diameter of 1 μm or less based on the volume diameter, and DH is the cumulative distribution [%] of particles with a particle diameter of more than 1 μm. (2) The mode diameter of pores in the range of 20 nm to 200 nm in diameter measured by mercury porosimetry is 40 nm to 70 nm.

[0012] Patent Document 1: JP-T-2011-514304 A Patent Document 2: JP-T-2011-515507 A Patent Document 3: Japanese Patent No. 5790537 A Patent Document 4: Japanese Patent Laid-Open No. 2022-156985 A

[0013] The ability of polymer electrolyte fuel cells (hereinafter referred to as "PEFC") to achieve both power generation characteristics and durability is an important characteristic for the widespread use of fuel cell vehicles (hereinafter referred to as "FCV"), and is an essential issue that must be resolved, particularly for commercial vehicles, where market growth is expected in the future.

[0014] Generally, one of the major causes of reduced durability in PEFCs is catalyst degradation, which is caused by oxidative consumption of the carbon support and dissolution of platinum nanoparticles. Both of these causes are caused by fluctuations in the electrode potential, particularly in the high-potential range exceeding 1 V. A solution to platinum dissolution is to increase the particle size to increase the time until dissolution. A solution to carbon support oxidative consumption is to increase the crystallinity (i.e., increase the in-plane size of the crystallites and the layer thickness) to suppress oxidative consumption of the carbon support, thereby reducing the area of ​​the carbon network plane edges that are the starting point for oxidative consumption and slowing the oxidation rate.

[0015] Power generation performance is governed by two main factors: the contribution of the metal catalyst (e.g., platinum nanoparticles) to the reaction (hereinafter also referred to as "catalyst utilization rate") and the diffusivity of oxidizing gases. The pore structure of the carbon support (porous carbon material) correlates with catalyst utilization rate, while the three-dimensional structure of the carbon support (e.g., dendritic structure) correlates with gas diffusivity. A desirable pore structure is one in which only pores large enough to accommodate a metal catalyst (e.g., platinum nanoparticles) of several nanometers are selectively present. Mesoporous carbon is generally considered to be a suitable support. While the pore size suitable for gas diffusion is unclear, the pore size of the catalyst layer for nucleic acids, estimated from various currently used carbon supports, is around several tens to hundreds of nanometers. 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, the carbon supports are heat-treated in an inert gas atmosphere at high temperatures of 1500°C or higher, preferably 2000°C or higher, to increase the crystallite size. However, this process has the side effect of collapsing the pores as the crystals grow. The higher 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 smallest structural unit called an aggregate, which is a structure formed by chemically fusion of an average of 10 to 20 primary particles of several tens of nanometers in size. Aggregates are fine powders that tend to remain suspended in the air, making them aerosols. Therefore, they are typically granulated for industrial use. To use carbon black as a catalyst support for fuel cells, it must be activated to make it porous and then heat-treated to enhance its crystallinity. However, the smaller the primary particles, the more pronounced the chemical bonding between aggregates that occurs during the heat treatment process. The inventors have confirmed this.

[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 clumps remain until the end. The thermally aggregated clumps in the catalyst layer reduce the number of pores with pore sizes 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 within the thermally aggregated clumps, resulting in a significant deterioration in power generation characteristics (particularly high-load characteristics) such as the ability to pass a large current.

[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 study has been conducted from the perspective of eliminating thermal agglomerates, and only manufacturing methods have been devised within the scope of common sense guidelines in the field, namely, a combination of activation to make the material 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 the problem of thermal agglomerates is not essentially solved. Patent Document 4 is an improvement related to a CO2 reduction method for the combustion of amorphous carbon, known as soot. ２ This involves mechanical crushing and classification during activation, which creates a new problem of mechanically destroying the three-dimensional structure of the carbon support, so it does not provide a fundamental solution to the problem of thermal agglomeration.

[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.

[0022] The means for solving the problems include the following aspects: <1> A carbon material for a catalyst support of a polymer electrolyte fuel cell, comprising a porous activated carbon black that satisfies the following requirements (A), (B), and (C): (A) a BET surface area (m) measured by nitrogen gas adsorption measurement; ２ (B) In the particle size distribution of the cumulative amount of particles passing through from small particles to large particles obtained by the volume-based particle size measurement using a laser light scattering method, when the total cumulative amount is set to 100%, the common logarithm of the particle diameters at 5% and 95%, respectively, is defined as D ５ (μm), D ９５ (μm), the difference Δ=D ９５ -D ５ (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 <2> The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to <1>, further satisfying the following requirement (D): (D) in the particle size distribution of the accumulated amount of passing through, the common logarithm of the particle size when the accumulated amount of passing through is 50% is D ５０ (μm), the common logarithm of the mode diameter is D ｍｏｄｅ (μm), (D ５０ -D ｍｏｄｅ ) / D ５０ is -0.16 or more and 0.20 or less. <3> A catalyst layer for a polymer electrolyte fuel cell, comprising the carbon material for a catalyst support of a polymer electrolyte fuel cell according to <1> or <2>. <4> A fuel cell, comprising the catalyst layer for a polymer electrolyte fuel cell according to <3>. <5> The fuel cell according to <4>, wherein the catalyst layer for a polymer electrolyte fuel cell is a catalyst layer on a cathode side.

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

[0024] 1 is a schematic diagram showing an example of the general configuration of a fuel cell according to the present disclosure. 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 a volume-based particle size measurement using a laser light scattering method. The common logarithm D of the particle size when the cumulative amount of passing particles is 5% is shown. ５ , the common logarithm of the particle diameter when the cumulative amount of passing particles is 95% D ９５ , the common logarithm of the particle diameter when the cumulative amount of passing particles is 50% D ５０ , the common logarithm of the mode diameter is D ｍｏｄｅ 1 is a graph for explaining the above.

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

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

[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 discovered the following: First, heat treatment not only causes pore collapse, but also causes agglomeration of the porous carbon black, and this agglomeration contributes to a decrease in power generation characteristics to the same extent as pore collapse. Specifically, there are occasional cases where the power generation characteristics are significantly decreased despite only minor pore collapse, and in such cases, the particle size distribution contains thermal agglomerates whose average particle size is clearly increased compared to before the heat treatment. Note that 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. As a result, they have discovered the following: Thermal agglomerates are thought to arise because contact points between aggregates form chemical bonds during the heat treatment process. Therefore, the solution to this problem involves selectively removing only the bonding points. A specific method is to selectively burn 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 to 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 mixture of ozone gas and an inert gas (e.g., argon gas), the reaction temperature, and the flow rate. Because ozone has a very strong oxidizing power, in the case of porous carbon materials, treatment is performed 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. Treatment under these conditions leaves the pore structure unchanged by nitrogen gas adsorption, significantly improving the particle size distribution of the aggregates and resulting in a particle size distribution that reflects the aggregate structure. Here, the particle size distribution is a commonly used graph in which particle frequency is expressed as volume, with 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. Although particle size distribution is based on empirical theory, bilateral symmetry is ideal in principle, and the mode diameter reflects the aggregate diameter, which is an aggregate of primary particle diameters. When carbon black with a developed dendritic structure is used to increase the pore volume of the catalyst layer, the mode diameter is preferably in the range of 5 to 13 times the primary particle diameter. In this way, by activating and heat-treating raw carbon black, porous carbon black can be obtained as a catalyst support carbon material, with aggregates being the smallest unit, and a particle size distribution that reflects the aggregate structure can be achieved.

[0032] Therefore, the inventors investigated whether the proportion of thermally agglomerated particles that are disintegrated is high, because this is important for battery performance. As a result, they obtained the following findings. The particle size distribution width of the cumulative amount of passing particles from small to large particles, obtained by volume-based particle size measurement using a laser light scattering method, can be defined by the particle sizes at 5% and 95% of the cumulative amount of passing particles falling within a certain range, where the total cumulative amount is 100%. Note that the shape of the particle size distribution is plotted on the horizontal axis as the common logarithm of the particle size, and the symmetry of the distribution is also obtained by plotting the particle size on the horizontal axis as the common logarithm of the particle size. Therefore, the particle size ranges at 5% and 95% are defined as numerical ranges on the 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 overvoltage at the cathode is thought to be caused by the following three main factors: (1) The magnitude of the ohmic resistance of the catalyst layer, which is a combination of two resistances: electron conduction resistance and proton conduction resistance; (2) The diffusion resistance of oxidizing gases within the catalyst layer; and (3) The electrochemical reaction on the catalyst metal surface, i.e., the chemical reaction involving electron transfer (proton oxidizing gas diffusion resistance).

[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 the deterioration of the dispersion state of porous carbon black is the formation of thermal agglomerates, a side effect of chemically bonding contact points between aggregate particles, the smallest units of porous carbon black, during the heat treatment process. Selective combustion of the surface of porous carbon black is an effective method for selectively removing contact points, and ozone oxidation is an effective way to achieve this. Optimizing the 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 form thermal agglomerates, thereby achieving a particle size distribution where the agglomerates were broken down. In other words, the particle size distribution of the porous carbon black obtained by ozone oxidation can achieve a particle size distribution equivalent to that of the raw carbon black. Furthermore, in addition to achieving a desired specific surface area, the breakup of thermal agglomerates can improve power generation characteristics (especially high-load characteristics).

[0036] In addition, the full width at half maximum ΔG (cm ) of the G band in the Raman spectrum obtained by Raman spectroscopy －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 catalyst support carbon material (i.e., porous activated carbon black) of the present disclosure is easily disintegrated during the ink preparation process for forming the catalyst layer, allowing for the production of a well-dispersed ink with few thermal agglomerates. In this disclosure, to determine whether the catalyst support carbon material is easily dispersible in ink, as described in the Examples below, a method was adopted in which the catalyst support carbon material was dispersed in a 10% by mass Liponox solution (an aqueous solution of a polyoxyalkylene phenyl ether surfactant, Liponox CN, 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 was measured using laser light scattering. If a particle size distribution reflecting the aggregate structure was obtained, it is expected that dispersion will be easily achieved during the ink production process.

[0039] The requirements (A), (B), and (C) will be explained below. From the viewpoint of further improving durability as well as power generation characteristics (particularly high-load characteristics), it is preferable that the carbon material for a catalyst support of the present disclosure satisfy 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 1200 m ２ / g, the thickness of the carbon walls forming the pore structure becomes thin. Specifically, the average number of layers on the carbon net 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, etc.), the number of layers becomes thin, and structural destruction is likely to occur even though the amount of carbon consumed is small. The deterioration of power generation characteristics due to durability is accelerated. When the BET specific surface area of ​​the porous carbon black is 400 m, 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 the oxidizing gas within the catalyst layer becomes longer, leading to a deterioration 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 section 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 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 defined as D. ５ (μm), D ９５ (μm), the difference Δ=D ９５ -D ５ is 0.35 or more and 2.00 or less.

[0045] There are two important reasons for using particle size distribution measurement by laser light scattering. First, the process of dispersing porous carbon black in water is a dispersion process that requires much less energy than the ink production process, and if good dispersion is obtained in this dispersion process, even better dispersion can be achieved in the ink used to form the catalyst layer. Second, the particle size distribution by laser light scattering allows quantitative measurement of something equivalent to the size distribution of porous carbon black. In other words, if the porous carbon black satisfies the above-mentioned particle size distribution range, the porous carbon black is dispersed as individual particles without agglomerating.

[0046] Porous carbon black difference Δ=D ９５ -D ５ The lower limit of the difference Δ is substantially 0.35. No carbon black exists that is smaller than this value. This is the theoretical lower limit of the raw carbon black produced by the furnace method, and the porous carbon black produced from it cannot exceed the lower limit of the raw carbon black. ９５ -D ５ If the value is more than 2.00, the aggregation is significant and the D ９５ is large, or the aggregate, which is the smallest unit of carbon black, is destroyed and D ５ The difference Δ of porous carbon black is small. Both significant aggregation and destruction of the aggregate structure reduce the power generation characteristics. ９５ -D ５ 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 of the particle diameter D ５ (μm) 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, －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 ensure the durability of fuel cells, i.e., to be resistant to two types of oxidation when maintained at a high potential exceeding 1 V: (1) resistance to oxidative attrition of the porous carbon black, and (2) resistance to localized oxidative attrition at the site of contact with the nano-sized catalytic metal when supported on the porous carbon black. A basic and effective measure to enhance this resistance is to improve the crystallinity of the 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 have an effect on improving resistance to oxidative attrition.

[0051] In the Raman spectroscopy of porous carbon black, the D band (1300-1400 cm) reflects the edge area of ​​the carbon network plane. －１ ) peak and the G band (1560-1620 cm ) reflecting the size of the carbon network plane and the number of layers. －１ Information about the crystallinity of porous carbon black can be obtained from the spectral shapes of the two peaks. When porous carbon black made porous by activation is heat-treated (also called graphitization treatment) at 1600°C to 1900°C in an inert gas atmosphere, the linewidth of the G band sensitively reflects changes in crystallinity due to the heat treatment.

[0052] The full width at half maximum ΔG of the G band of porous carbon black is 90 cm －１ If the G band of the porous carbon black is greater than 72 cm, the oxidation resistance of the porous carbon black will decrease. As a result, the overvoltage at high currents will increase and the high load characteristics will deteriorate. －１ If the temperature is less than 100°C, the porous carbon black, which is basically difficult to crystallize due to the porosity, will be treated at a higher temperature. As a result, the requirements (A) and (B) may not be satisfied. －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 ΔG of the G band 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 by the laser light scattering method, the common logarithm of the particle size when the cumulative amount of passing particles 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.

[0055] The particle size distribution of raw carbon black is approximately symmetrical between the small particle side and the large particle side, with the particle size (μm) on the horizontal axis expressed in common logarithm. Therefore, if there are few thermal agglomerates of porous carbon black, the particle size distribution of porous carbon black should be symmetrical. The ideal symmetry of the particle size distribution determined from the power generation characteristics is D ５０ and D ｍｏｄｅ Difference D ５０ In other words, if it is symmetric, (D ５０ -D ｍｏｄｅ ) / D ５０ = 0, median diameter D ５０ If the frequency on the small particle side is high, the difference becomes negative, and if the frequency on the large particle side 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 ５０ When the "(D)" of the porous carbon black is -0.16 or more, the thermal agglomerates are sufficiently broken down, the frequency of large particles is reduced, gas diffusion in the catalyst layer is increased, and power generation characteristics, particularly high load characteristics, are improved.５０ -D ｍｏｄｅ ) / D ５０ When the "(D)" of the porous carbon black is 0.20 or less, the thermal agglomerates are sufficiently broken down, the frequency of large particles is reduced, gas diffusion in the catalyst layer is increased, and power generation characteristics, particularly high load characteristics, are improved. 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 cell> Hereinafter, an example of a method for producing a carbon material for catalyst support of a polymer electrolyte fuel cell according to the present disclosure (hereinafter also referred to as a "method for producing a carbon material") will be described.

[0061] The method for producing a carbon material according to the present disclosure is, for example, a method comprising the following three steps. The method for producing a carbon material according to the present disclosure can produce a carbon material that satisfies requirements (A) to (C), preferably a carbon material that satisfies at least one of requirements (D) and (E) in addition to requirements (A) to (C) (i.e., porous activated carbon black). Activation step: an activation step in which raw carbon black is made porous by activation. 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 step: an ozone treatment step in which the porous raw carbon black that has been heat-treated in the heat treatment step (hereinafter referred to as heat-treated porous raw carbon black) is oxidized 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 carbon black, carbon black that satisfies the three specific 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 Diameter The size of the voids in the catalyst layer is determined by the three-dimensional structure and primary particle diameter of the raw carbon black. That is, because the three-dimensional structure is formed by a series of primary particles, the primary particle diameter x the number of beads = void size. If the three-dimensional structure is developed and the primary particle diameter is 20 nm or greater, gas diffusion in the catalyst layer becomes rate-limiting and the power generation performance does not deteriorate. That is, the preferred range of primary particle diameter is 20 nm to 80 nm. Since it becomes difficult to develop a three-dimensional structure when the primary particle diameter exceeds 80 nm, 80 nm is the practical limit for manufacturing. Pore formation by activation is presumed to occur from the outside to the inside, and since the surface area is continuously exposed to oxidation treatment, combustion loss is significant. Assuming this, the larger the primary particle diameter, the more likely it is that small pores are formed internally, but relatively large pores are formed near the surface. In fact, activation treatment of raw carbon black with a large primary particle diameter results in weaker pore development, even with increased mass reduction, compared to smaller particle diameters. That is, 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, raw carbon black with a larger primary particle size has higher resistance to oxidative attenuation than raw carbon black with a smaller primary particle size, assuming the same crystallinity as measured by Raman or X-ray diffraction. In other words, the larger the primary particle size, the more important durability becomes. 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 diameter of raw carbon black is one of the basic physical properties, and the primary particle diameter values ​​in the carbon black manufacturer's catalog are referenced. However, if the carbon black manufacturer's catalog value cannot be referenced, the arithmetic mean value of the primary particle diameter 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, "i. Electron microscope photography method," "ii. Particle size measurement," and "iii. Particle size calculation method," page 176 of the Carbon Black Handbook (edited by the Carbon Black Association, first edition 1971), were referenced. 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] Three-dimensional structure: Porous carbon black with a well-developed three-dimensional structure is preferred as a structure suitable for a catalyst support in a fuel cell. When a catalyst layer is formed with this three-dimensional structure, the catalyst layer becomes highly porous with voids, and the diffusion rate of oxidizing gas increases. Examples of physical properties that reflect the three-dimensional structure include DBP oil absorption and the distribution of mercury intrusion measured by mercury porosimetry.

[0067] DBP oil absorption is an industrial index of the typical colloidal physical properties of carbon black, and is the value listed in the catalog. The physical property specifications in this disclosure also use the value listed in the physical property table of the carbon black manufacturer. A specific 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 the DBP oil absorption is considered to correspond to the voids in the catalyst layer, a DBP oil absorption of 80 mL / 100 g corresponds to voids 1.4 times or more 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 in 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 performed by converting the hydrostatic pressure applied to mercury into pore diameters when assuming a cylindrical shape using the surface tension of mercury against the raw carbon black, and then obtaining the distribution of the integrated values ​​of the pore volumes larger than the pore diameters on the horizontal axis and the vertical axis, respectively. Raw carbon black with a three-dimensional structure absorbs mercury in proportion to the pore volume at a relative injection pressure corresponding to the pore size created 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 increment in the amount of mercury absorbed when the mercury injection 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 appropriate for the pores in the catalyst layer described above. If the increment 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 performance. On the other hand, the increase in the amount of mercury of 1.5 mL / g is the upper limit in principle in terms of production.

[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 granulated particle hardness JIS K 6219-4 Part 4: Determination of granulated particle size distribution

[0070] In Japan, raw carbon black is mainly granulated using a wet method using water. The raw carbon black is granulated by vigorously stirring and mixing 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 ease of dispersion can be improved by using a binder other than water, typically lignin, it is preferable to add no binder or a small amount of such binder. 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 Step) The activation step is a step in which raw carbon black is activated to make it porous. The mechanism of activation of raw carbon black is considered to be as follows. Raw carbon black is heated in a gas atmosphere containing water vapor (H ２ O), or CO ２ By exposing the raw carbon black to an activation gas such as HCl and maintaining it at 800°C to 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 peripheral portions (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 made porous through activation.

[0072] Increasing the activation temperature increases the reaction rate, accelerating combustion near the surface in contact with the high concentration of activation gas, while the concentration of activation gas diffusing inside becomes even lower, slowing down internal combustion. To develop pores inside without changing the surface condition, the reaction rate must be controlled appropriately. ２ Oxygen is the most suitable activation gas because it can control the reaction rate over a wide range of temperatures. The reasons why oxygen activation is not industrially applicable are as follows: ２ The oxidation reaction of raw carbon black with oxygen is an endothermic reaction, and the reaction will not proceed unless heat is applied. This reaction can be controlled by the amount of heat supplied, making it easy to scale up. On the other hand, the oxidation reaction of raw carbon black with oxygen is an exothermic reaction, and if the heat generated is greater than the heat removed, the temperature at the reaction site rises monotonically, making the reaction difficult to control. This phenomenon accelerates with scale up, so oxidation with oxygen is not suitable for mass production, and it is preferable to use water vapor or CO ２ As an activation gas, activation using

[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 depending on the reaction strength of the activation gas. The activation gas is water vapor or CO ２ When water vapor is used as the activation gas, the preferred temperature is 750 to 900°C, and CO ２ When the activation gas is used, the preferred temperature is 800 to 950°C. ２ / g), the mass loss 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 loss rate is, for example, 5 to 100 hours, preferably 10 to 80 hours, and more preferably 20 to 80 hours. Under activation conditions under which the time required to reach a mass loss rate of 50% by mass is shorter than 5 hours, differences arise, for example, compared to when the time required to reach the same mass loss rate is 20 hours, such as a smaller BET surface area or a larger volume of pores of 10 nm or larger in the pore size distribution obtained by BJH analysis of the nitrogen gas adsorption isotherm. The difference between the BET surface area and the pore size distribution is due to the following: if the reaction rate is too high, the surface combustion of the raw carbon black is relatively large compared to the internal combustion for forming internal pores, and part of the mass reduction is consumed by the surface combustion, preventing the BET specific surface area from increasing; and the surface combustion generates large irregularities of 10 nm or more (pores formed when depressions at the bonding points of primary particles develop due to the surface combustion). That is, to suppress the surface combustion, it is preferable to lower the activation temperature and lengthen the activation time. On the other hand, if the activation time is too long, such as when the time required for the mass reduction rate to reach 50% by mass exceeds 100 hours, the activation rate is too slow, so that the surface combustion prevails over the internal combustion, suppressing the development of pores, which is undesirable.

[0075] It is also preferable to activate under conditions where the activation gas pressure is increased. Because the activation gas concentration is high, the rate of the oxidation reaction increases almost in proportion to the concentration, and the activation time can be shortened without changing pore development, i.e., the BET surface area and pore size distribution, or without changing the surface combustion ratio. The activation time can be shortened in proportion to the pressure within a pressure range up to several atmospheres. At pressures above 6 atmospheres, the effect of the actual pressure increase is difficult to see, so 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 carbon black, and porous carbon black that satisfies requirement (A) can be produced. During the process of increasing the crystallinity in the heat treatment step, the texture and crystalline structure of the porous raw carbon black change toward a more stable graphite structure, causing the pores, which can be considered defects, to collapse. Therefore, the pore structure of the porous raw carbon black obtained in the activation step must be 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 step. In other words, in order to satisfy requirement (A) after the activation treatment step, the BET surface area of ​​the porous raw carbon black obtained in the activation step must be at least 400 m, the lower limit of requirement (A). ２ / g or more is preferred.

[0077] (Heat Treatment Step) The heat treatment step is a step in which the porous raw carbon black obtained in the activation step is heat-treated. The catalyst support is exposed to a noble potential of 1 V or more in the operating environment of the fuel cell. Because the ionomer has sulfonic acid groups, the catalyst support coated with the ionomer is 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 countermeasure 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 for 10 minutes to 10 hours under an inert gas atmosphere at atmospheric pressure (i.e., 1 atmosphere). In order to obtain a porous carbon material (i.e., porous activated carbon black) suitable for the present disclosure, it is important to select an optimal heat treatment temperature depending on the primary particle size of the raw carbon black. Specifically, if the primary particle size of the raw 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 1900°C. On the other hand, if the primary particle size of the raw carbon black is greater than 60 nm, it is easy to improve the crystallinity, so the upper limit of the heat treatment temperature is preferably 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 without collapse. 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 Step) 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. ３ ) has an oxidizing power second only to fluorine and can therefore be applied to the oxidation treatment of raw carbon black. Raw carbon black can have its blackness increased by adjusting the amount of oxygen-containing functional groups, and is therefore industrially used in the production of color carbon black. Taking advantage of its strong oxidizing power, it was applied to the selective oxidation of the surface of raw carbon black. Specifically, aggregates, which are the basic particles of raw carbon black, are agglomerated to form pellets, which are then subjected to activation and heat treatment in the pellet state to impart a pore structure and enhance crystallinity, resulting in heat-treated porous raw carbon black. However, during the heat treatment, the porous raw carbon black is exposed to high temperatures of 1400°C or higher in an inert gas atmosphere in its agglomerated state, causing the aggregates to chemically bond with each other, making them difficult to disintegrate even with mechanical action or ultrasonic waves in a medium. When ozone is brought into contact with the heat-treated porous raw carbon black, the carbon black surface is oxidized, resulting in the generation of CO. ２ This depletion burns off the binding sites, facilitating disintegration into aggregates.

[0083] For ozone treatment, any device capable of generating ozone at a rate of 10 mg / hour or more may 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 reduces the content of oxygen, which is the ozone raw material, and the amount of ozone generated decreases accordingly. Because ozone is unstable and self-decomposes over time, it is preferable to contact the heat-treated porous raw carbon black with a gas containing ozone while it is constantly flowing. To increase the reaction rate, ozone gas may be contacted with the heat-treated porous raw carbon black in a heated state.

[0084] The optimum 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 optimum 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 heat-treated porous raw carbon black. Optimizing the ozone treatment conditions according to the primary particle size of the raw carbon black makes it possible to obtain a desirable porous carbon material (i.e., porous activated carbon black). Since pores are likely to develop when the primary particle size of raw carbon black is 60 nm or less, even if the ozone treatment time is extended, there is little surface oxidation of the heat-treated porous raw carbon black. Therefore, it is easy to set a long upper limit for the heat treatment time. Specifically, a maximum ozone treatment time of 8 hours is appropriate. On the other hand, when the primary particle diameter of the raw carbon black exceeds 60 nm, pores are less likely to develop, so it is preferable to shorten the ozone treatment time compared to when the primary particle diameter of the raw carbon black is 60 nm or less. Specifically, the upper limit of the ozone treatment time is appropriately set to 5 hours. Ozone treatment times shorter than 1 hour are inappropriate because they generate a large amount of heat, selectively oxidizing the heat-generating sites and preventing a uniform reaction. Ozone treatment times longer than 8 hours are undesirable because oxidation inside the pores progresses, causing changes in the pore structure. Furthermore, the mass loss rate during 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 during 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 greater than 60 nm, the mass loss rate during ozone treatment is preferably 0.05 to 3.0% by mass.

[0085] <Catalyst Layer for Polymer Electrolyte Fuel Cell and Polymer Electrolyte Fuel Cell> A catalyst layer for a polymer electrolyte fuel cell according to the present disclosure will now be described, along with a polymer electrolyte fuel cell. The carbon material according to the present disclosure can be applied to, for example, catalyst layers 150 and 160 provided in a polymer electrolyte fuel cell 100 shown in FIG. 1. FIG. 1 is a schematic diagram showing an example of the overall configuration of a fuel cell according to the present disclosure. The polymer electrolyte fuel cell 100 shown in FIG. 1 includes separators 110 and 120, gas diffusion layers 130 and 140, catalyst layers 150 and 160, and an electrolyte membrane 170.

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

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

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

[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 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. ２ +4H ＋ +4e － →2H ２ O (E ０ = 1.23 V)

[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, but 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 ensure that the polymer electrolyte fuel cell 100 is practically usable. On the other hand, if the catalyst loading rate is 80% by mass or more, catalyst aggregation is likely to occur. Furthermore, if the catalyst layer 160 becomes too thin, flooding may occur.

[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, and is preferably more than 5 μm and less than 20 μm. In this case, the oxidizing gas is more likely to diffuse within the catalyst layer 160, and flooding is less likely to occur. If the thickness of the catalyst layer 160 is 5 μm or less, flooding is more likely to occur. If the thickness of the catalyst layer 160 is 20 μm or more, the oxidizing gas is less likely to diffuse within the catalyst layer 160, and the catalytic components near the electrolyte membrane 170 become less effective. In other words, there is a possibility that the catalyst utilization rate will decrease.

[0097] The electrolyte membrane 170 is composed of a proton-conducting electrolyte material. The electrolyte membrane 170 introduces protons generated in the oxidation reaction to the catalyst layer 160 (cathode). The type of electrolyte material is not particularly limited, and any electrolyte material used in conventional fuel cells, such as solid polymer fuel cells, may be used. An example of a suitable electrolyte material is an electrolyte resin. Examples of electrolyte resins include polymers with phosphate groups, sulfonic acid groups, etc. Specific examples include perfluorosulfonic acid polymers and polymers with benzenesulfonic acid, etc. Of course, other types of electrolyte materials may also be used. Examples of such electrolyte materials include inorganic and inorganic-organic hybrid electrolyte materials. The solid polymer fuel cell 100 may be a fuel cell that operates within a temperature range from room temperature (25°C) to 150°C.

[0098] <Method for manufacturing a polymer electrolyte fuel cell> The method for manufacturing the polymer electrolyte fuel cell 100 is not particularly limited, and may be the same as a conventional manufacturing method. However, the catalyst carrier uses the carbon material for a catalyst carrier of the present disclosure. Of the catalyst layers 150 and 160, it is preferable to use the carbon material for a catalyst carrier of the present disclosure for the catalyst carrier of at least the catalyst layer 160 that serves as the cathode. Of course, the carbon material for a catalyst carrier of the present disclosure may also be used for the catalyst carrier of both the catalyst layer 150 that serves as the anode and the catalyst layer 160 that serves as the cathode.

[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] <Method of measuring each parameter> (Measurement of nitrogen adsorption / desorption isotherm (BET specific surface area)) Approximately 30 mg of a sample of the carbon material for a catalyst support was weighed and vacuum dried at 120°C for 2 hours. Next, the sample was set in an automatic specific surface area measuring device (BELSORP MAX, manufactured by Microtrackbell Co., Ltd.), and the nitrogen adsorption / desorption isotherm was measured at a measurement temperature of liquid nitrogen temperature (approximately 77K) using nitrogen gas as the adsorbate. The BET specific surface area was determined by the relative pressure P / P in the nitrogen adsorption isotherm. ０ The BET value was calculated by BET analysis in the range of 0.05 to 0.15. The BET value was calculated using the calculation software attached to the device.

[0101] (Measurement of particle size distribution by laser light scattering method) 10 mg of a sample of the carbon material for catalyst carrier was weighed into a sample bottle, 1 mL of a 10 mass % Liponox solution (aqueous solution of a polyoxyalkylene phenyl ether type surfactant "Liponox CN" manufactured by Lion Corporation) was added, and the mixture was dispersed by irradiating ultrasonic waves for 10 minutes using an ultrasonic disperser. Next, the 10 mass % Liponox solution was added so that the transmittance was within a predetermined range, and the mixture was measured using a measuring device (LA-920 manufactured by Horiba, Ltd.). From the measurement, a particle size distribution of the cumulative amount of passed particles from small particles to large particles obtained from the particle size on a volume basis was obtained. Then, the following particle sizes were calculated from the particle size distribution of the cumulative amount of passed particles (see Figure 2). - Common logarithm D of the particle size when the cumulative amount of passed particles is 5% ５ (μm) Common logarithm D of particle diameter when the cumulative amount of passing particles is 95% ９５ (μm) Common logarithm D of particle diameter when the cumulative amount of passing particles is 50% 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 cumulative amount of passing particles.)

[0102] Then, based on these particle diameters, the difference Δ=D ９５ -D ５ , (D ５０ -D ｍｏｄｅ ) / D ５０ asked for.

[0103] (Raman Spectroscopic Measurement and Evaluation of ΔG) Approximately 30 mg of a sample of the carbon material for catalyst carrier was measured using a laser Raman spectrophotometer (manufactured by JASCO Corporation, NRS-3100 model). From the Raman spectrum obtained under the following measurement conditions, a band at 1560 cm called the G band was detected. －１ ~1620cm －１ The peak in the range of －１ The value of the wavelength (unit) was calculated. 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 arrangement: backscattering, objective lens: ×100 magnification, spot diameter: 1 μm, exposure time: 30 sec, observed wave number: 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, and 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 material carbon black. Because they were porous, they did not require any activation treatment. These raw material carbon blacks were subjected to a heat treatment step and an ozone treatment step.

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

[0107]

[0108] (Activation Treatment Step) 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, placing quartz wool to a height of about 1 cm on the dispersion plate, and then placing 5 g to 15 g of granulated raw material carbon black on top of that, and then setting the reaction tube in a vertical electric furnace normally used at 1100°C. Before heating, argon gas was flowed from the bottom to the top of the reaction tube to replace the inside of the reaction tube with argon gas, and then the temperature was increased at a rate of 10°C / min, and the reaction tube was heated to 850 to 950°C. After the predetermined temperature was reached, CO was added. ２ The gas was switched to argon gas. The flow rate was adjusted so that the linear velocity was 1 to 2 cm / sec at the furnace temperature. After treatment for a predetermined 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 temperature had cooled to near room temperature, the porous raw material carbon black was removed and its mass was measured, and the mass reduction rate of the yield relative to the charged mass (charged mass / recovered mass) was calculated. The activation temperature and activation time were adjusted as shown in Table 2 as activation treatment conditions so that the mass reduction rate was in the range of 55 to 80% by mass.

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

[0110] (Ozone Treatment Process) Pure oxygen was used as the input gas to a research-grade ozone generator manufactured by Kotohira Kogyo Co., Ltd. The ozone gas generation principle of this device is a so-called discharge type, where the ozone concentration is adjusted by the voltage and current between the electrodes and the gas flow rate. That is, 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 enhanced 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, leading to ignition. Therefore, in this experiment, the output gas from the ozone generator was diluted with argon gas to a level where the carbon would not ignite due to the reaction heat, resulting in the reaction gas. The amount of gas sent to the reaction tube was also controlled. The reaction amount of the ozone treatment was adjusted by the contact time with the output gas or by setting 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. If necessary, fine-fiber quartz wool was laid on top of the dispersion plate, and the heat-treated porous raw carbon black 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 that prevented powder from scattering outside the system and adjusted to a linear velocity of 0.5 to 2 mL sec to minimize reaction unevenness. The reaction volume was determined by mass change. At the beginning of the reaction, the mass increased by up to 0.5% due to the addition of oxygen functional groups, and then transitioned to a mass loss. The pore structure after ozone oxidation was investigated using nitrogen gas adsorption isotherms. As a result, the isotherms before and after treatment nearly overlapped, confirming that the surface had burned off and the pore size distribution due to internal combustion or other factors had not changed due to ozone oxidation. Table 2 shows the reaction temperature (controlled by the temperature of the electric furnace) and the 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] <Preparation of Membrane Electrode Assembly (MEA)> (Preparation of Catalyst) The carbon material for catalyst support (porous activated carbon black) of each example was added to an ethanol / water mixed solvent and dispersed by processing with an ultrasonic homogenizer for 2 minutes. A predetermined amount of a nitric acid solution of dinitrodiammine platinum complex was added thereto, and the platinum loading was adjusted to 40 mass %, and the mixture was stirred in an oil bath for 15 hours while maintaining a temperature several degrees lower than the boiling point. After processing, the mixture was filtered, dispersed again in distilled water, filtered again, and vacuum dried at 90°C for 5 hours to obtain a catalyst.

[0114] (Preparation of ink) An ionomer solution manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was diluted with ethanol to adjust the solid content concentration to 10% by mass, and then added dropwise to an ethanol solution in which a catalyst had been previously dispersed. Dispersion was further promoted using an ultrasonic homogenizer, and the mixture was stirred with 1 mm diameter glass beads for 10 to 15 hours. In this way, an ink for forming a catalyst layer was obtained.

[0115] <MEA Fabrication> The ink was uniformly applied to a Teflon (registered trademark) sheet using a sprayer and dried in an air circulating dryer at 60°C to prepare a decal with a catalyst layer formed thereon. Electrodes of a predetermined size of 36 mm were cut out from the decal. Two identical sheets were used as the positive and negative electrodes, and the positive and negative electrodes were placed on both sides of a Nafion membrane and heat-sealed. In this way, an MEA was obtained.

[0116] <Battery Evaluation> (Evaluation of power generation characteristics (high load characteristics)) Each MEA produced using the catalyst carrier carbon material (porous activated carbon black) of each example was assembled into a cell, which was then set in a fuel cell measuring device, and the performance of the fuel cell was evaluated according to the following procedure.

[0117] The oxidizing gas was supplied at a back pressure of 0.04 MPa by adjusting the pressure with a back pressure valve installed downstream of the cell, and air was supplied to the cathode side and pure hydrogen to the anode side 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 cell at 80°C to evaluate power generation.

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

[0119] (Evaluation of durability) In the above cell, while the anode was left as it was, argon gas was flowed through the cathode under the same humidification conditions as above, and the cell voltage was set to 1.0 V and held for 4 seconds, and then set to 1.3 V and held for 4 seconds, repeating this cycle (repeated square-wave voltage fluctuation). After 4,000 cycles of this repetitive square-wave voltage fluctuation, durability was investigated in the same manner as in the evaluation of power generation characteristics described above. Evaluation was performed using the following criteria of pass and fail ranks. The results are shown in Table 2. [Pass rank] A: Current density at cell voltage of 0.3 V was 1,100 mA / cm ２ B: A current density of 1000 mA / cm at a cell voltage of 0.3 V or more. ２ C: Current density at a cell voltage of 0.3 V is 950 mA / cm or more. ２ [Failure rank] D: Current density at cell voltage of 0.3 V is 950 mA / cm or more. ２ Something that is less than.

[0120]

[0121]

[0122]

[0123]

[0124] The above results will be explained below.

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

[0126] (#10-6 to #10 and #10-10A to #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. Then, power generation characteristics and durability were evaluated. The ozone treatment was performed at room temperature (25°C) and the treatment time was varied. Five types of samples were prepared to determine the mass loss rate (mass%) as a result of ozone treatment: a sample in which combustion did not progress and mass increased due to the addition of oxygen, and a sample in which mass loss due to combustion was less than 5 mass%. For #10-6 without ozone treatment, Δ=D ９５ -D ５ was outside the range of the present disclosure, and #10-10B had a too strong ozone treatment, resulting in a decrease in crystallinity (ΔG was outside the range of the present disclosure), and was unable to simultaneously satisfy both the power generation characteristics (high load characteristics) and durability. ９５ -D ５ The specifications for ΔG were met, and both power generation characteristics (high load characteristics) and durability were satisfied at the same time.

[0127] (10-10C to 10D, and #10-11 to 15) The raw carbon black 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 adjustments to achieve the BET specific surface areas 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. Then, the power generation characteristics (high load characteristics) and durability were evaluated. As a result, #10-11 to #14, which satisfied the physical properties of the present disclosure, exhibited excellent power generation characteristics (high load characteristics) and durability.

[0128] <Experimental Example #SH Series> (#SH-1 to #SH-4) Nitelon #SH was used as the raw carbon black, and the carbon black was activated at 850°C for 40 hours to create a porous structure. The subsequent heat treatment temperature was varied. The ozone treatment time was adjusted so that the mass loss rate at room temperature was 0.7 to 1.5% by mass. Four samples were produced in this manner. Then, 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 to 5 and 200-1A to 1C) Niteron #200 was used as the raw carbon black, and the carbon black was activated at 850°C for 25 hours to create a porous structure. The subsequent heat treatment temperature was varied. The ozone treatment was performed at room temperature (25°C). The higher the heat treatment temperature, the longer the treatment time. The treatment time was adjusted so that the mass loss rate was 0.8 to 5.2% by mass. Eight samples were prepared in this manner. Their power generation characteristics (high-load characteristics) and durability were then evaluated. As a result, #200-1B to 1C and #200-2 to 5, which met the physical properties of the present disclosure, exhibited excellent power generation characteristics (high-load characteristics) and durability.

[0130] Experimental Example #300IH Series (#300-1 to #300-5) Niteron #300IH was used as the raw carbon black, and the carbon black was activated at 850°C for 22 hours to create a porous structure. The subsequent heat treatment temperature was varied. Ozone treatment was performed at room temperature (25°C). The higher the heat treatment temperature, the longer the treatment time. The treatment time was adjusted so that the mass loss rate was 1.2 to 3.6% by mass. Five samples were prepared in this manner. Then, their power generation characteristics (high load characteristics) and durability were evaluated. As a result, #300-2 to #300-5, which met the physical properties of the present disclosure, demonstrated excellent power generation characteristics and durability.

[0131] <Experimental Examples GFY Series> (GFY-1 to GFY-8) GFY was used as the raw carbon black, and the carbon black was activated at 850°C for 50 to 110 hours to create a porous structure. 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. Then, 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 described herein, exhibited excellent power generation characteristics (high-load characteristics) and durability. In particular, GFY-2 to GFY-3 exhibited the most excellent durability characteristics 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 enhancing durability.

[0132] <Experimental Examples EC Series> (EC-1 to EC-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. Ozone treatment was performed at room temperature, with 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, all samples were ozone-treated, and therefore met the physical properties described in the present disclosure. Although slightly inferior in performance, they exhibited superior power generation characteristics (high-load characteristics) and durability compared to the comparative examples. The two raw carbon blacks in the EC Series were hard pellets that were difficult to crush by hand, suggesting that they underwent a different granulation process than the other raw carbon blacks. Furthermore, it is presumed that the hardness of these pellets prevents them from being sufficiently dispersed despite surface combustion by ozone treatment, resulting in poor performance in terms of 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 requirements 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: polymer electrolyte 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 documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A carbon material for a catalyst support in a polymer electrolyte fuel cell, comprising a porous activated carbon black that satisfies the following requirements (A), (B), and (C): (A) BET surface area (m2) measured by nitrogen gas adsorption measurement ２ (B) In the particle size distribution of the accumulated amount of passing particles from small particles to large particles obtained by the volume-based particle size measurement using a laser light scattering method, the common logarithm of the particle diameter at 5% and 95% of the accumulated amount of passing particles is defined as D ５ (μm), D ９５ (μm), the difference Δ=D ９５ -D ５ (C) In the Raman spectrum obtained by Raman spectroscopy, －１ ~1620cm －１ The full width at half maximum of the G band in the range of ΔG (cm －１ ) is greater than or equal to 72 and less than or equal to 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 accumulated amount of passing through, the common logarithm of the particle size when the accumulated amount of passing through 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. The fuel cell according to claim 4, wherein the catalyst layer for the polymer electrolyte fuel cell is a catalyst layer on the cathode side.