JP2017130446A - Carbon material for catalyst carrier, catalyst layer for solid polymer type fuel battery and solid polymer type fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide novel and improved carbon material for a catalyst carrier, catalyst layer, and solid polymer type fuel battery that can enhance the catalyst utilization rate by using no special material, enhance the catalyst utilization rate irrespective of humidification conditions, has high durability, and can be manufactured at low cost.SOLUTION: In a carbon material for a catalyst carrier capable of carrying a catalyst component for a solid polymer type fuel battery, a half band width of the G band measured by Raman spectroscopy, a BET specific surface area S(m/g) evaluated by a BET method, the ratio S/Sof the total specific surface area Sto the external specific surface area Swhich are evaluated by t plot analysis, and the external specific surface area Sevaluated by the t plot analysis are equal to a value within a predetermined range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon material for a catalyst carrier, a catalyst layer for a polymer electrolyte fuel cell, and a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell, which is a type of fuel cell, includes a pair of catalyst layers disposed on both sides of a solid polymer electrolyte membrane, a gas diffusion layer disposed outside each catalyst layer, and And a separator disposed on the outside. Of the pair of catalyst layers, one catalyst layer serves as the anode of the polymer electrolyte fuel cell, and the other catalyst layer serves as the cathode of the polymer electrolyte fuel cell. In a normal polymer electrolyte fuel cell, in order to obtain a desired output, a plurality of unit cells having the above components are stacked.

A reducing gas such as hydrogen is introduced into the separator on the anode side. The gas diffusion layer on the anode side diffuses the reducing gas and then introduces it into the anode. The anode includes a catalyst component, a catalyst carrier that supports the catalyst component, and an electrolyte material having proton conductivity. On the catalyst component, an oxidation reaction of the reducing gas occurs, and protons and electrons are generated. For example, when the reducing gas is hydrogen gas, the following oxidation reaction occurs.
H ₂ → 2H ⁺ + 2e ⁻ (E ₀ = 0V)

  Protons generated by this oxidation reaction are introduced to the cathode through the electrolyte material in the anode and the solid polymer electrolyte membrane. Further, the electrons are introduced into the external circuit through the catalyst carrier, the gas diffusion layer, and the separator. The electrons work in an external circuit and are then introduced into the cathode separator. The electrons are introduced into the cathode through the cathode-side separator and the cathode-side gas diffusion layer.

  The solid polymer electrolyte membrane is composed of an electrolyte material having proton conductivity. The solid polymer electrolyte membrane introduces protons generated by the oxidation reaction to the cathode.

An oxidizing gas such as oxygen gas or air is introduced into the cathode-side separator. The gas diffusion layer on the cathode side diffuses the oxidizing gas and then introduces it into the cathode. The cathode includes a catalyst component, a catalyst carrier that supports the catalyst component, and an electrolyte material having proton conductivity. On the catalyst component, a reduction reaction of the oxidizing gas occurs, and water is generated. For example, when the oxidizing gas is oxygen gas or air, the following reduction reaction occurs.
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (E ₀ = 1.23 V)

  Water generated by the reduction reaction is discharged to the outside of the fuel cell together with the unreacted oxidizing gas. Thus, in the polymer electrolyte fuel cell, power is generated using the energy difference (potential difference) between the oxidation reaction and the reduction reaction. In other words, electrons generated by the oxidation reaction work in an external circuit.

  Therefore, in the polymer electrolyte fuel cell, the gas diffusion path through which the reducing gas or oxidizing gas can move from the gas flow path of each separator to the catalyst component inside the anode or cathode is formed without being divided. is important. It is also important that a proton conduction path through which protons generated on the anode catalyst component can move to the cathode catalyst component through the solid polymer electrolyte membrane is formed without being interrupted. It is also important that an electron conduction path through which electrons generated on the anode catalyst component can move to the cathode catalyst component through an external circuit is formed without being interrupted. If these paths are divided, current cannot be efficiently extracted from the polymer electrolyte fuel cell.

  Therefore, in the catalyst layer, it is important that the pores constituting the gas diffusion path, the electrolyte material constituting the proton conduction path, and the catalyst carrier constituting the electron conduction path form a continuous network.

Japanese Patent No. 4,799,897 Japanese Patent No. 5358408 JP 2007-220414 A Patent No. 5213499 Special table 2008-501211 gazette International Publication No. 2014/185498 International Publication No. 2010/047415 Japanese Patent No. 5650542 JP-A-6-194174

  By the way, a very expensive noble metal such as Pt is used as a catalyst component of the polymer electrolyte fuel cell. For this reason, various attempts have been made to increase the catalyst utilization rate. This is because if the catalyst utilization rate is increased, the amount of the catalyst component used can be reduced without lowering the performance of the polymer electrolyte fuel cell.

  Specifically, conventionally, it exists at a contact portion (so-called three-phase interface) of a pore network constituting a gas diffusion path, an electrolyte material network constituting a proton conduction path, and a catalyst carrier network constituting an electron conduction path. It was thought that an electrode reaction (any of the above-mentioned reduction reaction and oxidation reaction) occurred on the catalyst component. Therefore, conventionally, it has been considered important to increase the contact area between the three-phase interface and the catalyst component as much as possible. Furthermore, it was considered important that these networks were formed as continuously as possible. This is because when these networks are divided, the three-phase interface is reduced.

  For this reason, in order to increase the utilization factor of the catalyst component, it has been proposed to make the catalyst component fine particles. By making the catalyst component fine particles, the surface area per unit mass of the catalyst component increases. For this reason, the contact area between the three-phase interface and the catalyst component increases.

  According to this method, the initial power generation performance is improved when a small amount of catalyst particles finely divided to about 1 to 3 nm is used. Therefore, it can be said that the utilization rate of the catalyst component is high in the initial stage of power generation. However, the finely divided catalyst particles are repeatedly eluted and deposited due to potential fluctuations during fuel cell operation. As a result, the catalyst component may be enlarged or eluted out of the catalyst layer. As a result, the catalyst utilization rate decreases.

  Therefore, in order for the catalyst component to withstand potential fluctuations, the catalyst component needs to have a certain particle size. For example, when the catalyst component is platinum, the size of the catalyst component that can withstand potential fluctuations is considered to be about 3 to 7 nm. For this reason, conventionally, various attempts have been made to increase the utilization rate of the catalyst component having such a particle size.

  For example, in the technique disclosed in Patent Document 1, a gas diffusion carbon material aggregated phase formed by agglomerating a gas diffusion carbon material not supporting a catalyst component as a main component is dispersed in the cathode catalyst layer. According to this technique, the pore network can be continuously formed by the gas diffusion carbon material aggregation phase. Therefore, an improvement in catalyst utilization particularly on the cathode side can be expected.

  In the technique disclosed in Patent Document 2, a particulate medium covered with an electrolyte material is added to the catalyst layer. In this technique, excessive covering of the catalyst carrier with the electrolyte material is suppressed, so that conduction between the catalyst carriers is ensured. That is, from the viewpoint of forming a three-phase interface, it is necessary to secure a certain contact area between the electrolyte material and the catalyst carrier. However, if the contact area becomes excessively large, the contact area between the catalyst carriers decreases. That is, the catalyst carrier network is divided. In the technique disclosed in Patent Document 2, since the excessive covering of the catalyst carrier with the electrolyte material is suppressed, the division of the catalyst carrier network is suppressed. Moreover, since pores on the surface of the catalyst carrier are not easily blocked by the electrolyte material, the pore network is prevented from being divided. Therefore, an improvement in catalyst utilization can be expected.

  However, in the techniques disclosed in Patent Documents 1 and 2, it is necessary to include a special material such as a gas diffusion carbon material or a particulate medium in the catalyst layer. For this reason, there has been a problem that the manufacturing cost of the polymer electrolyte fuel cell increases. In addition, even with these techniques, the catalyst utilization rate could not be sufficiently increased.

  Patent Documents 3 and 4 disclose techniques for increasing the catalyst utilization rate in a low humidified environment. That is, in order for the electrolyte material to conduct protons stably, the electrolyte material needs to be kept in a certain wet state. For this reason, a humidifier is often installed in a system including a polymer electrolyte fuel cell. The reducing gas and oxidizing gas are humidified by the humidifier. The humidified gas is then introduced into the polymer electrolyte fuel cell. However, humidifiers may be omitted in low cost systems. In this case, it is necessary to keep the inside of the catalyst layer in a wet state. For this reason, in the techniques disclosed in Patent Documents 3 and 4, a catalyst carrier having fine pores formed on the surface is used. According to the techniques disclosed in these, since the micropores formed in the catalyst support can retain moisture, the wet state of the electrolyte material can be maintained. In addition, the water | moisture content here is the water | moisture content produced | generated by the said reduction reaction, for example. As a result, separation of the electrolyte material network is suppressed, and an improvement in catalyst utilization can be expected.

  With the techniques described in Patent Documents 3 and 4, improvement in catalyst utilization can be expected under limited conditions such as in a low humidified environment. However, under highly humidified conditions, the oxidizing gas contains moisture generated by the reduction reaction in addition to moisture from the humidifier. Moisture contained in the oxidizing gas is particularly increased on the downstream side in the flow direction of the oxidizing gas. Thus, the oxidizing gas contains a lot of moisture. Therefore, the pores between the catalyst carriers may be blocked by moisture, and the pore network may be divided. Such a phenomenon is also called flooding. Furthermore, the micropores are completely blocked by moisture, and the catalyst component in the micropores may not be used for the electrode reaction. Therefore, the techniques disclosed in Patent Documents 3 and 4 have a problem that the catalyst utilization rate on the cathode side is greatly reduced particularly in a highly humidified environment.

  In the technique disclosed in Patent Document 5, the electrolyte material is allowed to enter the nano-order pores from the viewpoint of increasing the contact area between the catalyst component and the three-phase interface as much as possible. By allowing the electrolyte material to enter the nano-order pores, the catalyst component existing in the nano-order pores can easily come into contact with the electrolyte material. That is, the contact area between the catalyst component and the three-phase interface increases. However, even with this technology, the catalyst utilization rate has not increased so much. The reason for this is considered that the contact area between the catalyst component and the gas is reduced because the catalyst component is covered with the electrolyte material. As a result, it is considered that the electrode reaction on the catalyst component is inhibited. In particular, the catalyst component on the cathode side is susceptible to this influence.

  Patent Document 6 proposes a carbon material for a catalyst carrier made of special mesoporous carbon having a 002-plane crystallite diameter Lc of 1.5 nm or less. By using this carbon material for a catalyst carrier, the catalyst utilization rate can be improved. However, this carbon material for a catalyst carrier is a special carbon material obtained by decomposing silver acetylide or the like on a nano scale, and has a problem that the production cost is very high. Further, the carbon material for catalyst support has a problem that durability is not sufficient because crystallites are randomly arranged.

Patent Document 7 _discloses a ratio S _micro / S of a micropore specific surface area S _micro and a total specific surface area S _total having a specific surface area of 1000 m ² / g to 4000 m ² / g and a diameter of 2 nm or less by t-plot analysis. There has been proposed a carbon material for a catalyst support characterized by having a _total of 0.5 or more (synonymous with S _out / S _total being less than 0.5). Such a carbon material for a catalyst carrier has a property of storing water, and thus has excellent power generation characteristics under low humidification conditions.

  By the way, the single cell voltage of the polymer electrolyte fuel cell is about 1.0 V as an open circuit voltage. If the potential of the force sword is less than this value, the carbon material used as the catalyst support is electrochemically oxidized and consumed as carbon dioxide gas (deterioration of the support carbon material) can be substantially ignored. . However, under actual operating conditions, for example, when the fuel cell is started and stopped, the potential of the cathode may rise to 1.0 V or more. That is, when hydrogen and oxygen are mixed in the anode electrode, a hydrogen oxidation reaction in which hydrogen is oxidized and an oxygen reduction reaction in which oxygen is reduced occur in the anode electrode, thereby forming a local battery. Since the potential of the site where the oxygen reduction reaction occurs in the anode electrode becomes the oxygen reduction potential (about 1 V), the counter electrode facing through the electrolyte, that is, the cathode potential, further increases the battery voltage to the oxygen reduction potential in the anode. It is observed that the potential of the force sword increases to 1.0 V or more, and in some cases to about 1.5 V. Such mixing of hydrogen and oxygen in the anode electrode occurs when oxygen in the force sword electrode permeates the solid polymer electrolyte membrane and reaches the anode electrode. This phenomenon is unavoidable in principle as long as a fluorine-based membrane having high oxygen permeability is used, whether it is a stationary fuel cell application or a fuel cell automobile application.

In this way, when the cathode potential is 1.0 V or more, oxidation of the carbon material for the catalyst support represented by the reaction formula of C + O ₂ → CO ₂ occurs due to the high potential of the force sword, and the carbon material for the catalyst support becomes Deteriorates and wears out. As a result, the catalytic metal particles fall off from the carrier, and the amount of the catalyst that functions effectively decreases, resulting in a decrease in power generation performance. Alternatively, the gas supply failure occurs due to the thinning of the catalyst layer and the collapse of the pores due to the exhaustion of the carrier, and this also causes the power generation performance to deteriorate. In addition, deactivation of the catalyst metal due to high potential oxidation of platinum, which is the catalyst metal, may occur, and power generation performance is also degraded. Therefore, in an actual use environment, start-stop is repeatedly performed, and the power sword is exposed to a voltage of 1.0 V or more each time. When this is repeated over a long period of time, such potential fluctuations occur. Depending on the number of times, power generation performance decreases due to exhaustion of the carbon material for the catalyst support.

The carbon material proposed in Patent Document 7 has not been subjected to any treatment for suppressing such oxidation consumption. Therefore, the carbon material for a catalyst carrier of Patent Document 7 has a problem of low durability. In addition, for the purpose of imparting durability to the carbon material for catalyst support of Patent Document 7, if a treatment for suppressing oxidative consumption, for example, heat treatment at 1600 ° C. or higher in an inert atmosphere, the specific surface area decreases. When the present inventors investigated, the big factor of the area fall is the fall of a micropore specific surface area. That is, it is considered that the micropores were crushed by the high temperature heat treatment and the specific surface area was reduced. Accordingly, when the catalyst support carbon material of Patent Document 7 is simply treated to suppress oxidation consumption, the characteristic of Patent Document 7 is “the ratio S _micro / S _total of the micropore specific surface area S _micro and the total specific surface area S _total. It becomes difficult to maintain “0.5 or more”. Furthermore, since the specific surface area is also greatly reduced, the initial performance is not always satisfactory, and in particular, the catalyst utilization rate is lowered. As a result, there has been a problem that the characteristics of the excellent low load region that had before heat treatment disappeared.

In order to solve such a problem of Patent Document 7, Patent Document 8 and Patent Document 9 describe an activation process for increasing the specific surface area of a carbon material as a method for producing a carbon material for a catalyst carrier that improves the life characteristics of a fuel cell. A method of combining a high temperature heat treatment for highly graphitizing a carbon material has been proposed. In general, graphene grows and develops when highly graphitized, and the oxidation and wear resistance improves due to the growth of the graphene stacking order, but the micropores collapse, the specific surface area decreases, or The micropore specific surface area is reduced. A carbon material with a reduced specific surface area or a carbon material with a reduced micropore specific surface area has fewer graphene edges where the catalyst component can be adsorbed when the catalyst component is supported. Components tend to agglomerate and the particle size of the catalyst component becomes coarse, or the dispersibility of the catalyst component decreases. In order to prevent this, an “activation process” in which the carbon material is slightly oxidized and consumed in advance is performed to increase the specific surface area and the micropore specific surface area. Patent Document 8 and Patent Document 9 propose a method for producing a carbon material that combines such activation treatment and high graphitization treatment to achieve both high specific surface area and high oxidation resistance, and has a specific surface area of 700 m with a high degree of graphitization. ^A method for producing a carbon material of less than ² / g is illustrated. When the carbon material produced by such a method is used as a carbon material for a catalyst carrier of a fuel cell, the initial performance is maintained and the durability is extremely high. However, the initial performance is not always satisfactory due to the influence of the specific surface area reduced by the high graphitization treatment, and there is a problem that the catalyst utilization rate is particularly low.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to improve the catalyst utilization rate without using an expensive material, and the catalyst can be used regardless of humidification conditions. To provide a novel and improved carbon material for a catalyst carrier, a catalyst layer, and a polymer electrolyte fuel cell, which can improve the utilization rate, have high durability, and can be produced at low cost. It is in.

  In order to solve the above-mentioned problems, the present inventor has focused on a carbon material constituting the cathode-side catalyst carrier, that is, a cathode-side carbon material for the catalyst carrier. This is because, as described above, the catalyst utilization rate on the cathode side mainly decreases. As a result, the inventor has obtained the following knowledge.

1) In order to enhance the durability of the carbon material for the catalyst carrier, it is effective to graphitize the carbon material. That is, a carbon material generally used as a catalyst carrier for a polymer electrolyte fuel cell has a structure in which a plurality of crystallites are arranged. Each crystallite has a structure in which a plurality of condensed polycyclic aromatic skeletons (hereinafter also referred to as “graphene”) are stacked. The oxidation consumption of the carbon material is caused by carbon at the end of graphene (hereinafter also referred to as “edge carbon”) being oxidized to CO ₂ . Therefore, reducing edge carbon directly leads to suppression of oxidation consumption in the carbon material. Therefore, the carbon material is highly graphitized. Graphene grows and develops due to the high graphitization treatment, and the graphene stacking order develops. In other words, the high graphitization can greatly grow the crystallites constituting the carbon material for the catalyst carrier, so that the edge carbon can be reduced, and the durability of the carbon material for the catalyst carrier is enhanced. The high graphitization treatment is performed, for example, by performing a heat treatment at 1600 ° C. or higher in an inert atmosphere. Moreover, the graphitization degree of a carbon material can be evaluated by the half-value width of G band measured, for example by a Raman spectroscopy.

  2) As described above, when the contact between the electrolyte material and the catalyst component is increased, the catalyst utilization rate does not increase so much. The reason is considered that the catalyst component is covered with the electrolyte material. When the catalyst component is covered with the electrolyte material, the contact area between the catalyst component and the gas becomes small. As a result, the electrode reaction on the catalyst component is inhibited.

Therefore, the present inventor considered to support the catalyst component in the pores of the carbon material in order to avoid contact between the catalyst component and the electrolyte material as much as possible. Specifically, the present inventor activated a highly graphitized carbon material much more strongly than before. As a result, the specific surface area of the carbon material is extremely large (specifically up to 700 m ² / g), and in particular, the external specific surface area of the carbon material is extremely large (specifically, up to 300 m ² / g). succeeded in. Here, the external specific surface area corresponds to the external specific surface area obtained by the t-plot analysis of the nitrogen adsorption isotherm, and the ratio of the total specific surface area other than micropores (pores having a diameter of 2 nm or less) other than the specific surface area of the carbon material. Surface area.

  The inventor considered that the external specific surface area became extremely large because the carbon material had a hollow structure by the activation treatment. That is, at the initial stage of activation, the amorphous part of the gap between the crystallites and the edge of the graphene constituting the crystallite are preferentially scraped. Thereby, pores are formed on the surface of the carbon material. Thereafter, when the activation further proceeds, the amorphous portion existing inside the carbon material is scraped. Thereby, the carbon material of a hollow structure is produced. The hollow portion of the carbon material and the outer surface are connected by pores. The hollow carbon material has a very small “mass of carbon material”, which is the denominator of the specific surface area, and thus the external specific surface area increases.

  When the catalyst component was supported on such a carbon material, the catalyst utilization rate was greatly improved. The present inventor considers this reason as follows. That is, when a catalyst component is supported on a carbon material having a hollow portion, the catalyst component is also supported on the pores and the wall surface of the hollow portion. Since the electrolyte material cannot penetrate into the pores and the hollow portion, the number of catalyst components covered with the electrolyte material is reduced. Conventionally, only the catalyst component that contacts the electrolyte material was considered to be used for the reduction reaction. According to this idea, the catalyst component supported on the pores and the wall surface of the hollow portion is not in contact with the electrolyte material and therefore should not be used for the reduction reaction. Nevertheless, the catalyst utilization increased. Therefore, the catalyst components supported on the wall surfaces of the pores and the hollow part are also used for the reduction reaction.

  And it is thought that the edge part of a graphene is exposed to the wall surface of a pore and a hollow part. And the hydrophilic group is introduce | transduced by the activation process to the carbon atom which comprises the edge part of a graphene (henceforth such a carbon atom is also called "edge carbon atom"). For this reason, this inventor considered that this hydrophilic group became a moisture adsorption point. That is, the wall surfaces of the pores and the hollow portion have high hydrophilicity, and moisture is adsorbed at a high density on the wall surfaces of the pores and the hollow portion. And the catalyst component carry | supported by the wall surface of the pore and the hollow part is contacting this water | moisture content. And the proton in electrolyte material reaches | attains a catalyst component through the water | moisture content adsorbed by the wall surface of the pore and the hollow part. A reduction reaction occurs on the catalyst component. Thus, the present inventor considered that the moisture adsorbed on the wall surfaces of the pores and the hollow portion becomes a proton conductor instead of the electrolyte material. That is, the present inventor considered that such moisture becomes a proton conduction path. Further, since the hydrophilicity of the pores and the hollow portion is increased by the activation treatment, the electrolyte material can be maintained in a wet state even in a low humidified environment.

  The order of performing the activation treatment and the graphitization treatment is not particularly limited, but the activation treatment is preferably performed before the graphitization treatment. If the graphitization treatment is performed first, crystallites grow greatly, so that the portion that is scraped off by the activation treatment is reduced. For this reason, it becomes difficult to activate the carbon material, and it may be difficult to obtain a desired external specific surface area. On the other hand, a carbon material can be activated easily by performing an activation process previously. For this reason, the carbon material which has a desired external specific surface area can be produced easily. In addition, the activation process can be easily controlled.

  3) The hydrophilicity of the carbon material can be sufficiently increased only by the activation treatment, but may be further subjected to a hydrophilic treatment. Thereby, the hydrophilicity of the surface of the carbon material can be further increased.

  4) From the viewpoint of suppressing flooding in a highly humid environment, the external specific surface area needs to have a certain ratio with respect to the total specific surface area. If the external specific surface area is too small relative to the total specific surface area, many pores that easily retain moisture will be formed on the surface of the carbon material. As a result, moisture easily accumulates around the carbon material, and as a result, flooding can occur.

  As a method for evaluating the external specific surface area, t plot analysis is known. However, in the conventional t-plot analysis, there is a possibility that the micropores of the carbon material that has been highly graphitized so as to have the high durability required for a fuel cell cannot be accurately identified. In the t plot analysis, it is necessary to use a carbon material having as few micropores as a standard substance. However, the conventional standard substance sometimes has a higher proportion of micropores than a highly highly graphitized carbon material. For this reason, the conventional t-plot analysis has a problem that the micropores of the highly graphitized carbon material cannot be accurately determined. The inventor has intensively studied a method capable of discriminating such micropores in the carbon material. As a result, the present inventor has conceived that the carbon material obtained by heat-treating the carbon material at 2600 ° C. or higher is used as a standard substance. There are almost no micropores on the surface of such a standard material. Therefore, by performing t plot analysis using this standard substance, it becomes possible to accurately determine the micropores of the graphitized carbon material. The present inventor has arrived at the present invention based on these findings.

According to an aspect of the present invention, there is provided a carbon material for a catalyst carrier capable of supporting a catalyst component for a polymer electrolyte fuel cell, wherein the half band width of the G band measured by Raman spectroscopy is more than 30 cm ^{−1 and} more than 65 cm. less than ^-1, BET specific surface area _S BET to be evaluated by the BET method ^(m 2 / g) is less than 700 meters ² / g ultra 3000 m ² / g, a total specific surface area _{S total} is evaluated at t plot analysis The ratio S _out / S _total with the external specific surface area S _out is more than 0.3, and the external specific surface area S _out evaluated by the t plot analysis is more than 300 m ² / g. A carbon material is provided.

Here, BET specific surface area _S BET to be evaluated by the BET method ^(m 2 / g) may be less than 700 meters ² / g Ultra 1300 m ² / g.

Also, t plot analysis at Rated micropore specific surface area _S micro ^(m 2 / g) are, 250m ² / g may be less than ultra 700m ² / g.

  Here, the t plot analysis may be performed using a carbon material heat-treated at 2600 ° C. or more as a standard substance.

Further, the external specific surface area S _out evaluated by the t plot analysis may be more than 300 m ² / g.

  According to another aspect of the present invention, there is provided a catalyst layer for a polymer electrolyte fuel cell, comprising a catalyst component and the above-described carbon material for a catalyst carrier that supports the catalyst component.

  Here, the catalyst loading may be 30% by mass or more and less than 80% by mass.

  According to another aspect of the present invention, there is provided a polymer electrolyte fuel cell comprising the above catalyst layer.

  Here, the polymer electrolyte fuel cell may include a catalyst layer as a cathode-side catalyst layer.

According to the present invention described above, since the half width of G band is below 30 cm ^-1 super 65cm ^-1, it is possible to improve the durability of the polymer electrolyte fuel cell. Further, since the BET specific surface area _S BET ^(m 2 / g) is 700 meters ² / g Ultra 3000m less than ² / g, a large number of pores are formed on the surface of the carbon material. Therefore, more catalyst components can be supported in the pores. Furthermore, the external specific surface area S _out evaluated by the t plot analysis is more than 300 m ² / g. Therefore, the catalyst component can be supported not only on the wall surface of the pore but also on the wall surface of the hollow portion. Since edge carbon atoms are exposed on the wall surfaces of the pores and the hollow portion, the hydrophilicity of these wall surfaces is increased. Accordingly, protons reach these catalyst components. As a result, many catalyst components supported on the wall surfaces of the pores and the hollow portion can be used for the reduction reaction. Furthermore, since these catalyst components are not easily covered with the electrolyte material, they can be used for the reduction reaction more reliably. Therefore, the utilization factor of the catalyst component is improved. Furthermore, since the carbon material according to the present invention has high hydrophilicity, the electrolyte material can be maintained in a wet state even in a low humidification environment. Furthermore, since the ratio S _out / S _total between the _total specific surface area S _total and the external specific surface area S _out is more than 0.3, flooding is unlikely to occur even in a highly humidified environment. As described above, the carbon material according to the present invention can improve the catalyst utilization rate without using an expensive material, can improve the catalyst utilization rate regardless of humidification conditions, and has high durability. Have. Furthermore, since the carbon material of the present invention can be manufactured regardless of a special process as in Patent Document 6, it can be manufactured at low cost.

(A) It is sectional drawing which shows typically the carbon material which is a starting material. (B) It is sectional drawing which shows typically the carbon material in which the hollow part was formed by the activation which concerns on this embodiment. It is sectional drawing which shows typically a mode that the catalyst component was carry | supported by the carbon material for catalyst carriers which concerns on this embodiment. It is an example of the graph obtained by t plot analysis of this embodiment. 1 is a schematic diagram showing a schematic configuration of a fuel cell according to an embodiment of the present invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of carbon material for catalyst support>
First, the structure of the carbon material for catalyst carriers according to the present embodiment will be described. The carbon material for a catalyst carrier according to this embodiment is mainly used for a catalyst layer on the cathode side.

(1-1. Definition of terms)
The “pores” in the present embodiment are any of macropores, mesopores, and micropores. These hole classifications shall conform to the IUPAC classification.

  Further, the “catalyst utilization rate” is a ratio between the total number of catalyst components in the catalyst layer and the number of catalyst components used for the electrode reaction. In the experiment, it can be said that the catalyst utilization rate increased when the basis weight of the catalyst component was the same and the characteristics of the fuel cell were enhanced.

(1-2. Raman)
When the G band of the carbon material for the catalyst support is measured by Raman spectroscopy, the half band width (ΔG) of the G band is more than 30 cm ⁻¹ and less than 65 m ⁻¹ . The full width at half maximum (ΔG) of the G band is preferably more than 50 cm ⁻¹ and less than 65 m ⁻¹ . Here, the G band is a band detected in the range of 1550 to 1650 cm ⁻¹ of the Raman spectrum.

  When the half-value width of the G band is within this range, the degree of graphitization of the catalyst support carbon material is increased. For this reason, the carbon material for the catalyst carrier is less likely to be oxidized and consumed even when the start and stop of the solid polymer secondary battery is repeated. That is, the durability of the carbon material for the catalyst carrier is improved.

On the other hand, when the half-width of the G band is 30 cm ⁻¹ or less, the number of pores decreases, and the number of catalyst components supported in the pores decreases. In addition, the number of edge carbon atoms decreases, and the possibility that the micropores are crushed increases. In addition, when the half band width of the G band is 65 m ⁻¹ or more, durability cannot be expected.

In addition, as a method of adjusting the half band width of the G band of the carbon material for the catalyst support within the above range, for example, a process of graphitizing a carbon material that is a raw material of the carbon material for the catalyst support can be mentioned. Specifically, the carbon material is exposed to a high temperature environment of 1600 ° C. or higher. By graphitizing the carbon material, crystallites constituting the carbon material grow greatly. As a result, the half width of the G band of the carbon material can be a value within the above-described range. The heat treatment for graphitization is preferably 1800 to 2400 ° C. When the heating temperature is 1600 ° C. or lower, the crystallite growth is small and the edge carbon may be increased. As a result, the full width at half maximum of the G band is often 65 cm ⁻¹ or more. On the other hand, when the half width of the G band exceeds 2400 ° C., crystallites grow excessively, and the half width of the G band often becomes 30 cm ⁻¹ or less. In addition, even if it is a case where the half width of the G band is 30 cm ⁻¹ or less as a result of excessive graphitization treatment, the half width of the G band is within the above-described range by the activation treatment performed thereafter. Can be adjusted to the value.

(1-3. BET specific surface area)
BET specific surface area _S BET to be evaluated by the BET method ^(m 2 / g) is 700 meters ² / g Ultra 3000m less than ² / g. Preferably, BET specific surface area _S BET ^(m 2 / g) is 700 meters ² / g Ultra 1300m less than ² / g. When the BET specific surface area S _BET is a value within this range, a large number of pores are formed on the surface of the carbon atoms for the catalyst support, so that more catalyst components can be supported in the pores. When the BET specific surface area S _BET is 700 m ² / g or less, the catalyst support carbon materials tend to aggregate together during the step of supporting the catalyst component on the catalyst support carbon material or during the operation of the polymer electrolyte fuel cell. . In this case, the catalyst utilization rate tends to decrease. On the other hand, when S _BET (m ² / g) is 3000 m ² / g or more, the mechanical strength of the carbon material for the catalyst carrier decreases. As a result, the catalyst layer is easily crushed and the gas is less likely to diffuse into the catalyst layer. Moreover, when S _BET (m ² / g) is 1300 m ² / g or more, there is a possibility that compatibility with durability may be difficult. _{Specifically,} if the S BET ^(m 2 / g) is 1300 m ² / g or more, it is difficult to half width of G band as measured by Raman spectroscopy is controlled to be less than 30 cm ^-1 super 65cm ^-1 There is a possibility.

(1-4. Ratio of external specific surface area)
The ratio S _out / S _total of the _total specific surface area S _total (m ² / g) and the external specific surface area S _out (m ² / g) evaluated by the t plot analysis is more than 0.3. Here, the external specific surface area means the specific surface area of the external surface, that is, the portion facing the outside of the catalyst support carbon material. When S _out / S _total exceeds 0.3, flooding in a highly humid environment can be suppressed. On the other hand, when S _out / S _total is 0.3 or less, the number of pores (for example, micropores) in which moisture easily collects increases. In this case, the pores are easily clogged with moisture. When the pores are blocked with moisture, the catalyst component supported in the pores is submerged. And when a pore is obstruct | occluded with a water | moisture content, the catalyst component carry | supported in the pore will be submerged. When the catalyst component supported in the pores is submerged, the oxidizing gas cannot reach the catalyst component. In addition, since moisture easily accumulates around the catalyst support carbon material, the pore network is easily separated by moisture. As a result, the catalyst utilization rate decreases.

  Here, the t-plot analysis is a kind of analysis and evaluation method of nitrogen adsorption isotherm obtained by nitrogen adsorption measurement at a liquid nitrogen temperature of nitrogen gas. That is, in the t plot analysis, a deviation from the linearity of the nitrogen adsorption isotherm of the measurement sample is analyzed with reference to the nitrogen adsorption isotherm of a standard material that is the same material as the measurement sample and does not have micropores. This is a kind of comparative plot (Chemical Society of Japan, Colloid Chemistry I, Tokyo Chemical Dojin, 1995).

  The micropore specific surface area is obtained as a difference between the total specific surface area of the measurement sample and the external specific surface area in the t plot analysis. Here, the external specific surface area means the specific surface area of the portion facing the outside of the measurement sample. In the t plot analysis of the measurement sample having micropores, the following tendency is observed. That is, at an extremely low pressure, the nitrogen gas is adsorbed on the entire surface of the measurement sample including the micropore surface (that is, the surface of the micropore and the external surface other than the micropore). For this reason, in the region where t (that is, the adsorption thickness) is small, the adsorption amount is shifted upward with respect to the standard material having no micropores. That is, the slope of the t plot becomes larger than that of the standard material. From this slope, the total specific surface area of the measurement sample is calculated.

When the pore filling of the micropores is completed, the adsorption of nitrogen gas proceeds only to the external surface other than the micropores. Therefore, the slope of the t plot is small in the region where the adsorption thickness is large. From this inclination, the external specific surface area of the measurement sample (surface area of the external surface excluding the micropores of the measurement sample) is calculated. Therefore, the t plot of the measurement sample having micropores has an upwardly convex shape. On the other hand, when the measurement sample does not have micropores, the t plot is a straight line passing through the origin. An example is shown in FIG. The horizontal axis of FIG. 3 indicates the nitrogen gas adsorption thickness (nm), and the vertical axis indicates the nitrogen gas adsorption amount (such as molg ⁻¹ or cm ³ (STP) g ⁻¹ ). The t plot L has an upwardly convex shape, and is divided into a t plot L1 having a large inclination and a t plot L2 having a small inclination. The t plot L1 is a graph reflecting the adsorption to the micropores. On the other hand, the t plot L2 is a graph reflecting the adsorption of nitrogen gas to the external surface other than the micropores. Therefore, the external specific surface area of the measurement sample is obtained from the slope of the t plot L2, and the total specific surface area of the measurement sample is obtained from the slope of the nitrogen adsorption isotherm L1. And the surface area of a micropore is calculated | required from these differences. Note that the volume of the micropore is also obtained from the intercept (Y) of the t plot L2.

  By the way, in the process in which the present inventors proceed to study the present invention, a measurement sample subjected to the above graphitization treatment was prepared. Then, the present inventor attempted t-plot analysis of the measurement sample by using a nitrogen adsorption isotherm of a standard material that has been publicly disclosed. As a result, there arises a problem that the nitrogen adsorption isotherm of the measurement sample may have a downwardly convex shape. In this case, it cannot be determined whether or not the measurement sample satisfies the conditions of the carbon material for catalyst support of the present embodiment.

  The present inventor presumes that this is caused by the presence of more fine micropores in the standard material of the carbon material that is publicly available than the carbon material for the catalyst support used in the present embodiment. did. Then, the present inventor produced a carbon material with as few micropores as possible by heat-treating the measurement sample (or the same type of sample as the measurement sample) at a temperature of 2600 ° C. or higher in an inert atmosphere. It was. Here, the same kind of sample means a material having the same physical properties as the measurement sample. A similar sample is, for example, a carbon material if it is a carbon material, and more preferably, the type of the carbon material is the same. That is, carbon black is carbon black, and activated carbon is activated carbon. More preferably, the same brand and lot are used. Thus, the present inventor has solved the above problem. That is, when the t-plot analysis of the above-described measurement sample was performed using this standard substance, it succeeded in obtaining an upwardly convex nitrogen adsorption isotherm. Therefore, in the t plot analysis for discriminating the carbon material that can be used as the carbon material for the catalyst support, first, a standard material is prepared by heat-treating the measurement sample at a temperature of 2600 ° C. or higher in an inert atmosphere. Then, a t plot analysis may be performed using this standard substance. With such a reference material, the micropores are negligibly small. For this reason, t plot analysis can be performed correctly. The time for the heat treatment is not particularly limited. The longer the heat treatment time, the smaller the number of micropores. Therefore, the heat treatment may be performed until a desired nitrogen adsorption isotherm is obtained.

(1-5. Micropore specific surface area)
It is preferable micropore specific surface area _{S micro} evaluated at t plot analysis is less than 250 meters ² / g Ultra 700m ² / g. When the micropore specific surface area S _micro is a value within this range, there are many graphene edge portions where the catalyst component is likely to be adsorbed when the catalyst is supported, so that the support performance of the catalyst component is enhanced. In addition, since a hydrophilic group is present at the edge portion of graphene, there are many adsorbed waters that serve as proton conduction paths. That is, the catalyst utilization rate can be increased.

On the other hand, when the micropore specific surface area S _micro is 250 m ² / g or less, the graphene edge portion where the catalyst component is easily adsorbed when the catalyst is supported decreases. For this reason, when a catalyst component is supported at a high loading rate, the catalyst component aggregates, and the particle diameter of the catalyst component may become coarse, or the dispersibility of the catalyst component may decrease. Moreover, since the hydrophilic group which exists in the edge part of a graphene decreases, there exists a possibility that the adsorbed water used as a proton conduction path may decrease. That is, the catalyst utilization rate may be reduced. When the micropore specific surface area S _micro is 700 m ² / g or more, there is a possibility that compatibility with durability is difficult. Specifically, if the micropore specific surface area _{S micro} is 700 meters ² / g or more, be half width of G band as measured by Raman spectroscopy is difficult to control to less than 30 cm ^-1 super 65cm ^-1 There is sex.

(1-6. External specific surface area)
The external specific surface area S _out evaluated by the t plot analysis is more than 300 m ² / g. In this case, the carbon material for a catalyst support has a hollow portion. That is, since the carbon material for the catalyst support has a hollow structure, the “mass of the carbon material” which is the denominator of the specific surface area becomes extremely small. For this reason, external specific surface area _Sout will be over 300 m < ² > / g. Further, among the pores formed on the surface of the catalyst support carbon material, some of the pores are connected to the hollow portion. Moreover, since the pore and the hollow portion are formed by the activation treatment, the surface of the pore and the hollow portion has high hydrophilicity. That is, the edge carbon atoms of graphene are exposed on the surfaces of the pores and the hollow portion, and hydrophilic groups are introduced into these edge carbon atoms by the activation treatment. For this reason, the surface of a pore and a hollow part has high hydrophilicity. Therefore, moisture is adsorbed at a high density on the surfaces of the pores and the hollow portion. When the catalyst component is supported on such a catalyst support carbon material, the catalyst component is supported not only on the outer surface of the catalyst support carbon material but also on the surfaces of the pores and the hollow portion. Since protons are conducted to the catalyst component by the moisture adsorbed on the surfaces of the pores and the hollow portion, these catalyst components can be used for the reduction reaction. Furthermore, since these catalyst components are not easily covered with the electrolyte material, they can be used for the reduction reaction more reliably. Therefore, the utilization factor of the catalyst component is improved.

  Furthermore, since the surfaces of the pores and the hollow portion have high hydrophilicity, the carbon material for catalyst support can maintain the electrolyte material in a wet state even in a low humidification environment. Furthermore, the catalyst components are less likely to aggregate in the catalyst layer.

On the other hand, when the external specific surface area S _out is 300 m ² / g or less, the pores and the hollow portion are small, and therefore the number of catalyst components supported on the surface of the hollow portion is small. Furthermore, since the hydrophilicity of the pores and the hollow portion is also reduced, the density of moisture adsorbed on these surfaces is also reduced. For this reason, proton conduction resistance increases. As a result, the catalyst utilization rate decreases. Furthermore, when the catalyst component is to be supported on the catalyst support carbon material at a high density, the catalyst component is likely to aggregate. For this reason, when the polymer electrolyte fuel cell is operated for a long time, the catalyst utilization rate tends to decrease.

A preferable range of the external specific surface area S _out is more than 400 m ² / g. In this case, more catalyst components can be supported on the surfaces of the pores and the hollow part. In addition, the proton conduction resistance is significantly reduced. As a result, the catalyst utilization rate is significantly improved.

In Patent Document 6, the specific surface area (m ² / g) of mesopores is analyzed by the DH (Dollimore-Heal) method. And in the carbon material disclosed by patent document 6, the specific surface area of the mesopore evaluated by this method is 400 m < ² > / g or more. On the other hand, in this embodiment, the external specific surface area is analyzed by the t plot method. In the t-plot method, the external specific surface area is measured with the portion other than the micropores as the external surface. This is because the mesopores are included in the portions other than the micropores. However, as a result of studies by the present inventors, it has been found that the catalyst utilization rate may be lowered even when the specific surface area of the mesopores is large by the DH method. The pore diameter calculated by the DH method is presumed to be because the actual carbon material structure cannot be reflected when slit-like pores are included because the pores are assumed to be cylindrical. On the other hand, in the t plot analysis, the external specific surface area is calculated from the difference from the adsorption behavior of the reference substance having no pores, so that a value reflected in the actual structure can be obtained regardless of the pore shape. In fact, as shown in the comparative example described later, in the carbon material disclosed in Patent Document 6, the specific surface area of the mesopores calculated by the DH method is certainly 400 m ² / g or more, but calculated by the t plot. The external specific surface area is much smaller than 300 m ² / g.

Examples of the method of setting the external specific surface area of the carbon material for the catalyst support to more than 300 m ² / g include a method of activating the carbon material as a starting material much more strongly than before. The type of the activation treatment is not particularly limited, and any treatment may be used as long as the treatment gives a defect to the molecular structure of the carbon material. Examples of the activation treatment include a treatment in which a carbon material is heated in an environment in which a gas such as oxygen, air, water vapor, carbon dioxide, or an inert gas containing these gases is circulated. Thereby, the carbon material for catalyst carriers having a hollow structure can be produced. Hereinafter, based on FIG. 1, a mode that a hollow part is formed in a carbon material by an activation process is demonstrated.

  FIG. 1A is a cross-sectional view schematically showing a carbon material 110 as a starting material. A plurality of pores 110 a are formed on the surface of the carbon material 110. When the activation treatment is performed on the carbon material 110, the amorphous portion of the gap between the crystallites and the edge of the graphene constituting the crystallite are preferentially scraped at the initial stage of activation. And the bottom part of the pore 110a advances to the center side of the carbon material 110, while the whole surface of the carbon material 110 is thinned. Thereafter, the bottom of the pores 110a reaches an amorphous part existing inside the carbon material. When the activation further proceeds, this amorphous portion is preferentially scraped. As a result, a carbon material for catalyst carrier 110A shown in FIG. 1B is produced. The catalyst support carbon material 110A has a hollow portion 110b, and the pores 110a connect the hollow portion 110b and the outer surface 110e. Furthermore, the wall surface 110c of the pore 110a and the wall surface 110d of the hollow portion 110b have high hydrophilicity.

  FIG. 2 shows a state in which the catalyst component 120 is supported on the catalyst support carbon material 110A. The catalyst component 120 is supported not only on the outer surface 110e of the catalyst support carbon material 110A but also on the wall surface 110c of the pore 110a and the wall surface 110d of the hollow portion 110b. FIG. 2 shows the catalyst component 120 supported on the wall surface 110d of the hollow portion 110b.

  Note that the hydrophilicity of the carbon material can be sufficiently increased only by the activation treatment, but a hydrophilic treatment may be further performed. Thereby, the hydrophilicity of the surface of the carbon material can be further increased. The type of the hydrophilic treatment is not particularly limited, and any treatment may be used as long as the treatment improves the hydrophilicity of the carbon material. Examples of the hydrophilization treatment include a treatment in which a carbon material is immersed in a heated nitric acid aqueous solution.

(1-7. Types of carbon material for catalyst support)
The type of the carbon material for the catalyst support is preferably a chemically stable carbon material. A preferred example of the carbon material for the catalyst carrier is carbon black. The carbon material for the catalyst support may be other types of carbon materials, such as graphite, carbon fiber, activated carbon, etc., pulverized products thereof, carbon compounds such as carbon nanofibers, carbon nanotubes, and the like. The carbon material for the catalyst support may be a mixture of two or more of these.

<2. Method for producing carbon material for catalyst support>
Next, the manufacturing method of the carbon material for catalyst supports is demonstrated. First, a carbon material as a starting material is prepared. Here, the carbon material is preferably a chemically stable carbon material. A preferable example of the carbon material is carbon black. The carbon material may be other types of carbon materials, such as graphite, carbon fiber, activated carbon, etc., pulverized products thereof, carbon compounds such as carbon nanofibers, carbon nanotubes, and the like. The carbon material may be a mixture of two or more of these.

Next, the carbon material is activated. The type of the activation treatment is not particularly limited, and any treatment may be used as long as the treatment gives a defect to the molecular structure of the carbon material. Examples of the activation treatment include a treatment in which a carbon material is heated in an environment in which a gas such as oxygen, air, water vapor, carbon dioxide, or an inert gas containing these gases is circulated. The activation process may be performed until the external specific surface area exceeds 300 m ² / g.

Next, the carbon material is graphitized. Specifically, the carbon material is exposed to a high temperature environment of 1600 ° C. or higher. By graphitizing the carbon material, crystallites constituting the carbon material grow greatly. As a result, the half width of the G band of the carbon material can be a value within the above-described range. The heat treatment for graphitization is preferably 1800 to 2400 ° C. The graphitization treatment may be performed until the half width of the G band becomes greater than 30 cm ⁻¹ and less than 65 m ⁻¹ .

Next, the above-described parameters, that is, the half width of the G band, the BET specific surface area S _BET (m ² / g), S _out / S _total , and the external specific surface area S _out are measured. Then, a carbon material in which these parameters are values within the above-described range is selected as the carbon material for the catalyst support. In addition, when it is desired to further improve the hydrophilicity of the carbon material for the catalyst support (specifically, for example, when it is desired to further improve the characteristics of the polymer electrolyte fuel cell), an additional hydrophilic treatment may be performed. The type of the hydrophilic treatment is not particularly limited, and any treatment may be used as long as the treatment improves the hydrophilicity of the carbon material. Examples of the hydrophilization treatment include a treatment in which a carbon material is immersed in a heated nitric acid aqueous solution. A carbon material for a catalyst carrier is produced through the above steps.

<3. Structure of polymer electrolyte fuel cell>
The carbon material for a catalyst carrier according to the present embodiment is applicable to the polymer electrolyte fuel cell 1 shown in FIG. 4, for example. The polymer electrolyte fuel cell 1 includes separators 10 and 20, gas diffusion layers 30 and 40, catalyst layers 50 and 60, and an electrolyte membrane 70.

  The separator 10 is an anode-side separator, and introduces a reducing gas such as hydrogen into the gas diffusion layer 30. The separator 20 is a cathode-side separator, and introduces an oxidizing gas such as oxygen gas or air into the gas diffusion aggregation phase. The type of separators 10 and 20 is not particularly limited as long as it is a separator used in a conventional fuel cell, for example, a polymer electrolyte fuel cell.

  The gas diffusion layer 30 is a gas diffusion layer on the anode side, diffuses the reducing gas supplied from the separator 10, and then supplies it to the catalyst layer 50. The gas diffusion layer 40 is a gas diffusion layer on the cathode side, diffuses the oxidizing gas supplied from the separator 20, and then supplies it to the catalyst layer 60. The type of the gas diffusion layers 30 and 40 is not particularly limited as long as it is a gas diffusion layer used in a conventional fuel cell, for example, a polymer electrolyte fuel cell. Examples of the gas diffusion layers 30 and 40 include porous carbon materials such as carbon cloth and carbon paper, and porous metal materials such as metal mesh and metal wool. In addition, as a preferable example of the gas diffusion layers 30 and 40, the separator side layer of the gas diffusion layer is a gas diffusion fiber layer mainly composed of a fibrous carbon material, and the catalyst layer side layer is mainly composed of carbon black. And a gas diffusion layer having a two-layer structure that becomes a micropore layer.

The catalyst layer 50 is a so-called anode. In the catalyst layer 50, an oxidation reaction of the reducing gas occurs, and protons and electrons are generated. For example, when the reducing gas is hydrogen gas, the following oxidation reaction occurs.
H ₂ → 2H ⁺ + 2e ⁻ (E ₀ = 0V)

  Protons generated by the oxidation reaction reach the catalyst layer 60 through the catalyst layer 50 and the electrolyte membrane 70. Electrons generated by the oxidation reaction reach the external circuit through the catalyst layer 50, the gas diffusion layer 30, and the separator 10. The electrons are introduced into the separator 20 after working in an external circuit. Thereafter, the electrons reach the catalyst layer 60 through the separator 20 and the gas diffusion layer 40.

  The configuration of the catalyst layer 50 serving as the anode is not particularly limited. That is, the configuration of the catalyst layer 50 may be the same as that of the conventional anode, the same configuration as that of the catalyst layer 60, or a configuration having higher hydrophilicity than the catalyst layer 60. May be.

The catalyst layer 60 is a so-called cathode. Within the catalyst layer 60, a reduction reaction of the oxidizing gas occurs, and water is generated. For example, when the oxidizing gas is oxygen gas or air, the following reduction reaction occurs. Water generated by the oxidation reaction is discharged to the outside of the fuel cell 1 together with the unreacted oxidizing gas.
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (E ₀ = 1.23 V)

  Thus, the fuel cell 1 generates power using the energy difference (potential difference) between the oxidation reaction and the reduction reaction. In other words, electrons generated by the oxidation reaction work in an external circuit.

  The catalyst layer 60 preferably contains the carbon material for a catalyst carrier according to the present embodiment. That is, the catalyst layer 60 includes the catalyst support carbon material according to the present embodiment, the electrolyte material, and the catalyst component. Thereby, the catalyst utilization factor in the catalyst layer 60 can be increased, and as a result, the catalyst utilization factor of the polymer electrolyte fuel cell 1 can be increased.

  The catalyst loading rate in the catalyst layer 60 is not particularly limited, but is preferably 30% by mass or more and less than 80% by mass. Here, the catalyst loading rate is preferably mass% of the catalyst component with respect to the total mass of the catalyst-supporting particles (particles in which the catalyst component is supported on the catalyst support carbon material). In this case, the catalyst utilization rate is further increased. When the catalyst loading is less than 30% by mass, it may be necessary to increase the thickness of the catalyst layer 60 so that the polymer electrolyte fuel cell 1 can be practically used. On the other hand, when the catalyst loading is 80% by mass or more, catalyst aggregation tends to occur. In addition, the catalyst layer 60 becomes too thin and flooding may occur.

  The mass ratio I / C between the mass I (g) of the electrolyte material in the catalyst layer 60 and the mass C (g) of the carbon material for catalyst support is not particularly limited, but is preferably more than 0.5 and less than 5.0. . In this case, the pore network and the electrolyte material network can be compatible, and the catalyst utilization rate is increased. On the other hand, when the mass ratio I / C is 0.5 or less, the electrolyte material network tends to be poor and the proton conduction resistance tends to be high. When the mass ratio I / C is 5.0 or more, the pore network may be divided by the electrolyte material. In either case, the catalyst utilization rate may decrease.

  Further, the thickness of the catalyst layer 60 is not particularly limited, but is preferably more than 5 μm and less than 20 μm. In this case, the oxidizing gas easily diffuses in the catalyst layer 60 and flooding is less likely to occur. When the thickness of the catalyst layer 60 is 5 μm or less, flooding is likely to occur. When the thickness of the catalyst layer 60 is 20 μm or more, the oxidizing gas is difficult to diffuse in the catalyst layer 60, and the catalyst component in the vicinity of the electrolyte membrane 70 is difficult to work. That is, the catalyst utilization rate may be reduced.

  The electrolyte membrane 70 is made of an electrolyte material having proton conductivity. The electrolyte membrane 70 introduces protons generated by the oxidation reaction into the catalyst layer 60 that is a cathode. Here, the type of the electrolyte material is not particularly limited as long as it is an electrolyte material used in a conventional fuel cell, for example, a polymer electrolyte fuel cell. A suitable example is an electrolyte material used in a polymer electrolyte fuel cell, that is, an electrolyte resin. Examples of the electrolyte resin include polymers introduced with phosphoric acid groups, sulfonic acid groups, and the like, for example, polymers containing perfluorosulfonic acid polymer and benzenesulfonic acid. Of course, the electrolyte material according to the present embodiment may be another type of electrolyte material. Examples of such an electrolyte material include inorganic and inorganic-organic hybrid electrolyte materials. The fuel cell 1 may be a fuel cell that operates within a range of normal temperature to 150 ° C.

<4. Manufacturing method of polymer electrolyte fuel cell>
The production method of the polymer electrolyte fuel cell 1 is not particularly limited, and may be a production method similar to the conventional one. However, it is preferable to use the catalyst support carbon material according to this embodiment for the catalyst support on the cathode side.

<1. Preparation of carbon material>
As carbon materials used as starting materials, three types of carbon materials, MCND (Escarbon manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), EC300 (Ketjen Black EC300 manufactured by Lion Corporation), and EC600JD (Ketjen Black EC600JD manufactured by Lion Corporation) are used. Got ready.

<2. Parameter measurement method>
(2-1. Raman)
For the measurement of Raman spectrum, NRS-7100 type (manufactured by JASCO Corporation) was used. Measurement conditions are: excitation laser wavelength: 532 nm, laser power: 100 mW (sample irradiation power: 0.1 mW), microscopic arrangement: Backscattering, slit size: 100 μm × 100 μm, objective lens: × 100, spot diameter: 1 μm, exposure time: 30 seconds, number of observation waves: 3200 to 750 cm ⁻¹ , number of integrations: 2 times. And the half value width ((DELTA) G) of the peak intensity of the range of 1550-1650 cm < ^-1 > called G band was computed.

(2-2. BET specific surface area)
The BET specific surface area was measured using BELSORPmini manufactured by Microtrac Bell. Specifically, a measurement sample vacuum-dried at 120 ° C. was placed in an automatic specific surface area measurement apparatus, and an adsorption isotherm was created using nitrogen gas. Then, the BET specific surface area (S _BET ) was calculated using the attached software BELMaster.

(2-3. T plot analysis and DH (Dollimore-Heal) analysis)
As a standard substance, Ketjen Black EC600JD (manufactured by Lion) that was heat-treated at 2600 ° C. for 2 hours in an argon stream was prepared. And the nitrogen adsorption isotherm of this standard substance was measured using BELSORPmini made from Microtrac Bell. This nitrogen adsorption isotherm was registered as reference data for the soft BELMaster attached to BELSORPmini. The nitrogen adsorption isotherm of the measurement substance was measured using BELSORPmini, and t-plot analysis and DH analysis were performed using the standard sample as reference data using BELMaster. In the t plot analysis, the total specific surface area S _total (m ² / g), the micropore specific surface area S _micro , and the external specific surface area S _out (m ² / g) were calculated (ie, analyzed) by the t plot method. In the DH analysis, the specific surface area (m ² / g) of the mesopores was calculated (ie, analyzed) by the DH method.

<3. Example 1>
(3-1. Carbon material)
EC300 was prepared as a carbon material to be a starting material.

(3-2. Activation treatment)
The carbon material was subjected to H ₂ O activation treatment. Specifically, argon gas was passed through distilled water maintained at 90 ° C. Next, the obtained humidified argon gas was brought into contact with the carbon material maintained at 950 ° C. for 2 hours.

(3-3. Graphitization treatment)
The carbon material subjected to the activation treatment was held at 1800 ° C. for 2 hours in an argon stream to perform graphitization treatment. The carbon material for a catalyst carrier according to Example 1 was produced through the above steps.

(3-4. Platinum support treatment)
A carbon material for a catalyst support was dispersed in an aqueous chloroplatinic acid solution. Subsequently, the dispersion was kept at 50 ° C., and aqueous hydrogen peroxide was added while stirring the dispersion. Then, the addition of _Na 2 _S 2 _{O 4} aqueous dispersion to obtain a catalyst precursor. The catalyst precursor was filtered, washed with water, and dried, and then subjected to reduction treatment in a 100% H ₂ stream at 300 ° C. for 3 hours. Through the above steps, catalyst-carrying particles in which platinum was supported by 50% by mass with respect to the total mass of the catalyst-carrying particles were produced.

(3-5. Adjustment of coating ink)
The catalyst-carrying particles were placed in a container, and a 5% by mass Nafion solution (DE521 manufactured by DuPont) was added thereto so that the ratio of Nafion was 1.5 parts by mass with respect to 1 part by mass of the carbon material for the catalyst support. The dispersion was then gently stirred. Thereafter, the catalyst-carrying particles were pulverized with ultrasonic waves. Thereafter, the dispersion was further stirred to obtain a coating ink.

(3-6. Preparation of catalyst layer)
The obtained coated ink was sprayed on a Teflon (registered trademark) sheet, and then dried in argon at 80 ° C. for 10 minutes, and then in argon at 120 ° C. for 60 minutes to prepare a catalyst layer. The platinum basis weight of the catalyst layer was 0.10 mg / cm ² . Here, the platinum basis weight was measured in the following steps. First, the produced Teflon sheet and the catalyst layer were cut into a 3 cm square, and the total mass of the Teflon sheet and the catalyst layer was measured. Next, the mass of the Teflon sheet after the catalyst layer was peeled off with a scraper was measured. Next, the catalyst layer mass was calculated from the difference between the previous mass and the subsequent mass. Next, the weight per unit area of platinum was determined by calculation from the ratio of platinum in the solid content of the catalyst ink.

(3-8. Production of MEA)
Next, an MEA (membrane electrode assembly) was produced using the produced catalyst layer. Specifically, a Nafion membrane (N112 manufactured by DuPont) was cut into a 6 cm square with a cutter knife, and the catalyst layer applied on the Teflon sheet was cut into a 2.5 cm square with a cutter knife. These catalyst layers were used as an anode and a cathode so that the center part of the Nafion membrane was not displaced so that a laminate was produced. Next, the laminate was pressed at 120 ° C. and 100 kg / cm ² for 10 minutes. After the pressed laminate was cooled to room temperature, only the Teflon sheet for both the anode and cathode was carefully peeled off. As a result, the anode and cathode catalyst layers were fixed to the Nafion membrane.

Next, a commercially available carbon cloth (LT 1200W manufactured by E-TEK) as a gas diffusion layer was cut into a 2.5 cm square with a cutter knife. Then, the cut carbon cloth was laminated so that there was no deviation between the anode and the cathode, thereby producing a laminate. Subsequently, MEA was created by pressing a laminated body for 10 minutes at 120 degreeC and 50 kg / cm < ² >. The weight of the fixed catalyst layer was determined from the difference between the weight of the Teflon sheet with the catalyst layer before pressing and the weight of the Teflon sheet peeled after pressing, and the amount of platinum per unit area was calculated from the mass ratio of the composition of the catalyst layer. It was confirmed that the concentration was 0.10 mg / cm ² .

(3-9. Fuel cell power generation performance test)
Each of the produced MEAs was incorporated into a cell, and the performance of the fuel cell was evaluated using a fuel cell measurement device. Specifically, the following evaluation was performed.

  First, performance evaluation under “high humidification” conditions was performed. Air was supplied to the cathode and pure hydrogen was supplied to the anode so that the gas utilization rates were 30% and 60%, respectively. Each gas pressure was adjusted by a back pressure valve provided downstream of the cell and set to 0.1 MPa. The cell temperature was set at 80 ° C. Further, air and pure hydrogen supplied to the fuel cell were each humidified by passing through distilled water kept at 80 ° C. (that is, bubbling). And the humidified gas was supplied to the cell. After supplying gas to the cell under such conditions, the current density was gradually increased until the cell voltage reached 0.6 V, and the cell voltage was fixed at 0.6 V for 60 minutes. Thereafter, the cell voltage was fixed at 0.85 V, and the current density after 60 minutes was recorded as the power generation performance.

  The power generation performance result is based on the current density obtained in the power generation performance test of Comparative Example 1, and when the current density is lower than the standard, x, and when the current density is higher than 0% and within 20% or less from the standard, ○ In the case where the current density is higher than 20% in the range above the standard, it was marked as ◎.

  Next, performance evaluation under “low humidification” conditions was performed. Air was supplied to the cathode and pure hydrogen was supplied to the anode so that the gas utilization rates were 30% and 60%, respectively. Each gas pressure was adjusted by a back pressure valve provided downstream of the cell and set to 0.1 MPa. The cell temperature was set at 80 ° C. Further, air and pure hydrogen supplied to the fuel cell were each humidified by passing through distilled water kept at 50 ° C. (that is, bubbling). And the humidified gas was supplied to the cell. After supplying gas to the cell under such conditions, the current density was gradually increased until the cell voltage reached 0.6 V, and the cell voltage was fixed at 0.6 V for 60 minutes. Thereafter, the cell voltage was fixed at 0.85 V, and the current density after 30 minutes was recorded as the power generation performance.

  The power generation performance result is based on the current density obtained in the power generation performance test of Comparative Example 1, and when the current density is lower than the standard, x, and when the current density is higher than 0% and within 20% or less from the standard, ○ In the case where the current density is higher than 20% in the range above the standard, it was marked as ◎.

(3-10. Fuel cell durability performance test)
For the cells in which either of the power generation performances was evaluated as ◯ or ◎, the durability performance test was performed after the power generation performance test. The durability performance test was performed in the following steps. That is, after the power generation performance test, the cathode gas was changed to Ar, and the gas was sufficiently replaced. Here, the argon gas was humidified by passing through distilled water kept at 80 ° C. (that is, performing bubbling). Then, using a potentiostat, the process of holding the cathode at 0.6 V for 4 seconds and the process of holding at 1.3 V for 4 seconds were repeated 200 times with reference to the anode through which hydrogen gas flows. Thereafter, the cathode gas was replaced with air, and a power generation performance test was performed under the conditions of the fuel cell performance evaluation test. Here, the air was humidified by passing through distilled water kept at 50 ° C. (that is, bubbling). On the basis of the current density before the potential change, the evaluation was “good” when the current density after the potential change was over 50%, and the evaluation was “x” when the current density was 50% or less.

  The carbon material for the catalyst support of Example 1 satisfied all the requirements of this embodiment. And the result of the high humidification power generation performance test was (circle), the result of the low humidification power generation performance test was (circle), and the result of the fuel cell durability performance test was (circle). The results are summarized in Table 1.

<4. Example 2>
The same process as in Example 1 was performed except that the CO2 activation process was performed as the activation process. Here, in Example 2, the following treatment was performed as the CO ₂ activation treatment. Specifically, it was contacted for 2 hours 100% by volume of CO ₂ gas to the carbon material held at 1050 ° C.. The carbon material for the catalyst carrier of Example 2 satisfied all the requirements of this embodiment. In particular, the external specific surface area of Example 2 was more than 400 m ² / g. Therefore, the result of the high humidification power generation performance test was 性能, the result of the low humidification power generation performance test was ◎, and the result of the fuel cell durability performance test was 電池. The results are summarized in Table 1.

<5. Example 3>
The same treatment as in Example 1 was performed except that EC600JD was used as a starting carbon material, that graphitization was performed prior to the activation treatment, and that O ₂ activation treatment was performed as the activation treatment. . Here, in Example 3, the following process was performed as the O ₂ activation process. Specifically, 1 volume% O ₂ gas diluted with argon gas was brought into contact with a carbon material maintained at 950 ° C. for 6 hours. The carbon material for a catalyst support of Example 3 satisfied all the requirements of this embodiment. And the result of the high humidification power generation performance test was (circle), the result of the low humidification power generation performance test was (circle), and the result of the fuel cell durability performance test was (circle). The results are summarized in Table 1.

<6. Example 4>
The same treatment as in Example 1 was performed except that EC600JD was used as a starting carbon material, graphitization was performed prior to the H ₂ O activation treatment, and hydrophilic treatment was performed after the activation treatment. went. Here, in Example 4, the temperature of the H ₂ O activation treatment was 900 ° C., and the treatment time was 6 hours. Moreover, the following process was performed as a hydrophilic treatment. That is. The carbon material was immersed in concentrated nitric acid (specific gravity 1.38) and held at 100 ° C. for 2 hours. Next, after diluting concentrated nitric acid with sufficient water, the carbon material dispersion was filtered. Next, washing of the carbon material with distilled water was repeated until the pH of the filtrate reached 5.5 or higher. The obtained carbon material was vacuum-dried at 110 ° C. Through the above steps, a carbon material for a catalyst support was obtained. The carbon material for a catalyst support of Example 4 satisfied all the requirements of this embodiment. In particular, the external specific surface area of Example 4 was more than 400 m ² / g. For this reason, the result of the high-humidity power generation performance test was ○, the result of the low-humidity power generation performance test was ◎, and the result of the fuel cell durability performance test was ○. The results are summarized in Table 1.

<7. Example 5>
Except for using EC600JD as a carbon material as a starting material, performing CO ₂ activation treatment as activation treatment, setting the graphitization treatment temperature to 1900 ° C., and performing hydrophilic treatment after graphitization treatment. The same processing as in Example 1 was performed. Here, in Example 5, the following process was performed as the CO ₂ activation process. Specifically, it was contacted for 2 hours 100% by volume of CO ₂ gas to the carbon material held at 1050 ° C.. The hydrophilization treatment was the same as in Example 4. The carbon material for a catalyst support of Example 5 satisfied all the requirements of this embodiment. In particular, the external specific surface area of Example 5 was more than 400 m ² / g. For this reason, the result of the high-humidity power generation performance test was ○, the result of the low-humidity power generation performance test was ◎, and the result of the fuel cell durability performance test was ○. The results are summarized in Table 1.

<8. Example 6>
The same treatment as in Example 1 was performed except that EC600JD was used as a starting carbon material, graphitization treatment was performed prior to the activation treatment, and CO ₂ activation treatment was performed as the activation treatment. . Here, in Example 3, the following process was performed as the CO ₂ activation process. Specifically, it was contacted for 2 hours 100% by volume of CO ₂ gas to the carbon material held at 1050 ° C.. The carbon material for a catalyst support of Example 6 satisfied all the requirements of this embodiment. In particular, the external specific surface area of Example 6 was more than 400 m ² / g. Therefore, the result of the high humidification power generation performance test was 性能, the result of the low humidification power generation performance test was ◎, and the result of the fuel cell durability performance test was 電池. The results are summarized in Table 1.

<9. Comparative Example 1>
MCND (Escarbon manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was used as a carbon material that was a starting material. And the graphitization process similar to Example 1 was performed to the carbon material. The graphitization temperature was 2000 ° C. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 1, the specific surface area of the mesopores evaluated by the DH method was certainly 400 m ² / g or more, but the external specific surface area S _out was much smaller than 300 m ² / g, and S _out / _Stotal was much smaller than 0.3. And in the comparative example 1, the result of the high humidification power generation performance test and the low humidification power generation performance test was favorable. For this reason, the current density obtained in Comparative Example 1 was used as the reference value for the fuel cell power generation performance test. However, even though the carbon material was graphitized at 2000 ° C., the current density decreased to 50% or less in the fuel cell durability performance test. That is, the result of the fuel cell durability performance test was x. This is probably because the external specific surface area S _out is much smaller than 300 m ² / g, and S _out / S _total is much smaller than 0.3. The results are summarized in Table 1.

<10. Comparative Example 2>
EC300 was used as the starting carbon material. This carbon material was graphitized in the same manner as in Example 1. Next, the same hydrophilic treatment as in Example 4 was performed on the carbon material. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 2, S _BET was 700 m ² / g or less, the external specific surface area S _out was 300 m ² / g or less, and S _out / S _total was 0.3 or less. And the result of the high humidification power generation performance test was x, and the result of the low humidification power generation performance test was x. In Comparative Example 2, since the S _BET was 700 m ² / g or less, the external specific surface area S _out was 300 m ² / g or less, and the S _out / S _total was 0.3 or less, it is estimated that the catalyst utilization rate was lowered. . The results are summarized in Table 1.

<11. Comparative Example 3>
EC300 was used as the starting carbon material. This carbon material was subjected to the same H ₂ O activation treatment as in Example 1. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 3, the half width of the G band was 65 cm ⁻¹ or more. And the result of the high humidification power generation performance test was x, and the result of the low humidification power generation performance test was ○. However, the result of the fuel cell durability performance test was x. In Comparative Example 3, the half-width of the G band was 65 cm ⁻¹ or more, so it was estimated that the durability was insufficient. The results are summarized in Table 1.

<12. Comparative Example 4>
EC300 was used as the starting carbon material. This carbon material was subjected to CO ₂ activation treatment. Here, in Comparative Example 4 were subjected to the following process as a CO ₂ activation treatment. Specifically, 100% by volume of CO ₂ gas was brought into contact with a carbon material maintained at 900 ° C. for 2 hours. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 4, S _BET was 700 m ² / g or less, and the external specific surface area S _out was 300 m ² / g or less. And the result of the high humidification power generation performance test was x, and the result of the low humidification power generation performance test was x. In Comparative Example 4, since the S _BET was 700 m ² / g or less and the external specific surface area S _out was 300 m ² / g or less, it is estimated that the catalyst utilization rate was lowered. The results are summarized in Table 1.

<13. Comparative Example 5>
EC600JD was used as a carbon material as a starting material. This carbon material was graphitized in the same manner as in Example 1. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 5, S _BET was 700 m ² / g or less, and the external specific surface area S _out was 300 m ² / g or less. And the result of the high humidification power generation performance test was x, and the result of the low humidification power generation performance test was x. In Comparative Example 5, since the S _BET was 700 m ² / g or less and the external specific surface area S _out was 300 m ² / g or less, it is estimated that the catalyst utilization rate was lowered. The results are summarized in Table 1.

<14. Comparative Example 6>
EC600JD was used as a carbon material as a starting material. This carbon material was subjected to the same graphitization treatment as in Example 1, and then an H ₂ O activation treatment. However, in Comparative Example 6, the temperature of the H ₂ O activation treatment was 850 ° C., and the treatment time was 3 hours. Evaluation similar to Example 1 was performed using the carbon material for catalyst carriers obtained as a result. In Comparative Example 6, S _BET was 700 m ² / g or less, and the external specific surface area S _out was less than 300 m ² / g. In Comparative Example 6, since the temperature of the activation process was low (that is, the activation process was weak), it is estimated that S _BET and the external specific surface area S _out became the above values. And the result of the high humidification power generation performance test was x, and the result of the low humidification power generation performance test was x. In Comparative Example 6, since the S _BET was 700 m ² / g or less and the external specific surface area S _out was 300 m ² / g or less, it is considered that the catalyst utilization rate was lowered.

<15. Verification on catalyst loading>
By performing the same treatment as Comparative Example 2, Comparative Example 5, Example 1, and Example 5 except that the catalyst loading is changed in increments of 10% by mass within the range of 30 to 80% by mass, Catalyst supported particles were prepared. Then, using a transmission electron microscope, the catalyst-carrying particles were observed at a magnification of 500,000, and the presence or absence of aggregation of the catalyst component (that is, platinum particles) was confirmed.

  As a result, in the catalyst-carrying particles of Comparative Example 2 and Comparative Example 5, no aggregation of the catalyst component was observed when the catalyst loading rate was 30 to 50% by mass. However, aggregation of the catalyst component was observed when the catalyst loading was 60% by mass. In contrast, in the catalyst-carrying particles of Example 1 and Example 5, when the catalyst loading rate was 30 to 70% by mass, no aggregation of the catalyst component was observed, but the catalyst loading rate was 80% by mass. In some cases, some aggregation was observed. As a result, it was found that the catalyst loading is preferably 30% by mass or more and less than 80% by mass.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

1 Solid Polymer Fuel Cell 10, 20 Separator 30, 40 Gas Diffusion Layer 50, 60 Catalyst Layer 70 Electrolyte Membrane

Claims (9)

A carbon material for a catalyst carrier capable of supporting a catalyst component for a polymer electrolyte fuel cell,
Half width of G band as measured by Raman spectroscopy is less than 30 cm ^-1 super 65cm ^-1,
BET specific surface area _S BET to be evaluated by the BET method ^(m 2 / g) is less than 700 meters ² / g Ultra 3000 m ² / g,
The ratio S _out / S _total of the _total specific surface area S _total and the external specific surface area S _out evaluated by the t plot analysis is more than 0.3,
A carbon material for a catalyst support, wherein an external specific surface area S _out evaluated by t plot analysis is more than 300 m ² / g. Wherein the BET specific surface area _S BET to be evaluated by the BET method ^(m 2 / g) is less than 700 meters ² / g Ultra 1300 m ² / g, a carbon material for a catalyst carrier of claim 1, wherein. t plot analysis at Rated micropore specific surface area _S micro ^(m 2 / g), characterized in that it is less than 250 meters ² / g Ultra 700 meters ² / g, for catalyst carrier according to claim 1 or 2 Carbon material.   The carbon material for a catalyst support according to any one of claims 1 to 3, wherein the t-plot analysis is performed using a carbon material heat-treated at 2600 ° C or higher as a standard substance. The carbon material for a catalyst support according to any one of claims 1 to 4, wherein an external specific surface area S _out evaluated by t plot analysis is more than 400 m ² / g. A catalyst component;
A catalyst layer for a polymer electrolyte fuel cell comprising the carbon material for a catalyst carrier according to any one of claims 1 to 5, which carries the catalyst component.   7. The catalyst layer for a polymer electrolyte fuel cell according to claim 6, wherein the catalyst loading is 30% by mass or more and less than 80% by mass.   A solid polymer fuel cell comprising the catalyst layer according to claim 6. 9. The polymer electrolyte fuel cell according to claim 8, wherein the polymer electrolyte fuel cell includes the catalyst layer as a cathode-side catalyst layer.

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