JP6854685B2 - A carbon material for a catalyst carrier of a polymer electrolyte fuel cell and a method for producing the same, and a catalyst carrier for a polymer electrolyte fuel cell using the carbon material for the catalyst carrier. - Google Patents

Description

The present invention relates to a carbon material for a catalyst carrier of a polymer electrolyte fuel cell and a method for producing the same, and a catalyst carrier for a solid polymer fuel cell using the carbon material for a catalyst carrier, and in particular, a polymer electrolyte fuel. The present invention relates to a carbon material for a catalyst carrier useful as a catalyst carrier for preparing a catalyst for a battery, and a method for producing the same.

In recent years, a polymer electrolyte fuel cell that can operate at a low temperature of 100 ° C. or lower has attracted attention, and is being developed and put into practical use as a drive power source for vehicles and a stationary power generation device. A general polymer electrolyte fuel cell has a membrane electrode assembly (MEA) in which catalyst layers serving as an anode and a cathode are arranged on both outer sides of a proton conductive electrolyte membrane. The basic structure (unit cell) is a structure consisting of a gas diffusion layer arranged outside the catalyst layer with the membrane electrode assembly interposed therebetween and a separator arranged outside the gas diffusion layer. , Consists of stacking the required number of unit cells to achieve the required output.

Then, in the unit cell of such a polymer electrolyte fuel cell, an oxidizing gas such as oxygen or air is applied to the cathode side from the gas flow paths of the separators arranged on the anode side and the cathode side, respectively. Fuels such as hydrogen are supplied to the anode side, and these supplied oxidizing gases and fuels (these are sometimes referred to as "reaction gases") are supplied to the catalyst layer via the gas diffusion layer, respectively. Work is taken out by utilizing the energy difference (potential difference) between the chemical reaction occurring in the catalyst layer of the anode and the chemical reaction occurring in the catalyst layer of the cathode. For example, hydrogen gas as the fuel, and when the oxygen gas is used as the oxidizing gas, a chemical reaction occurring in the anode catalyst layer [oxidation ^{_{reaction: H 2 → 2H + + 2e}} - (E 0 = 0V) ] When the chemical reaction occurring in the catalyst layer of the cathode: ^- is extracted energy difference between [the reduction reaction ^{_{O 2 + 4H + + 4e →}} 2H 2 O (E 0 = 1.23V) ] a (potential difference) as work.

Here, with respect to a catalyst that forms a catalyst layer as described above and causes a chemical reaction, a porous carbon material is usually used as a catalyst carrier from the viewpoints of electron conductivity, chemical stability, and electrochemical stability. As the catalyst metal, Pt or Pt alloy, which can be used in a strongly acidic environment and exhibits high reaction activity for both oxidation reaction and reduction reaction, is mainly used. As for the catalyst metal, the above-mentioned oxidation reaction and reduction reaction generally occur on the catalyst metal. Therefore, in order to increase the utilization rate of the catalyst metal, it is necessary to increase the specific surface area per mass, which is usually the case. Uses particles with a size of about several nm.

As for the catalyst carrier that supports such catalyst metal particles, in order to enhance the supporting ability as a carrier, that is, to increase the number of sites for adsorbing and supporting the above-mentioned catalyst metal particles of about several nm. Therefore, it is necessary to use a porous carbon material having a large specific surface area, and the volume of mesopores having a pore diameter of 2 to 50 nm so as to support the above-mentioned catalytic metal particles in a highly dispersed state as much as possible. That is, it is required to be a porous carbon material having a large mesopore volume, and at the same time, when a catalyst layer serving as an anode and a cathode is formed, the reaction gas supplied into the catalyst layer is diffused without resistance. Further, in order to discharge the water (produced water) generated in the catalyst layer without delay, it is necessary to form fine pores in the catalyst layer suitable for diffusion of the reaction gas and discharge of the produced water.

Therefore, conventionally, as a porous carbon material having a relatively large specific surface area and mesopore volume and at the same time having a dendritic structure in which branches are three-dimensionally developed, for example, Cabot's Vulcan XC-72 or Lion. The company's EC600JD and Lion's EC300 are used. Attempts have also been made to develop a porous carbon material having a more suitable specific surface area and mesopore volume as a carbon material for a catalyst carrier and a more suitable dendritic structure, which has attracted particular attention in recent years. As a starting point, there is a dendritic carbon nanostructure that is manufactured using a metal acetylide such as silver acetylide having a three-dimensionally branched three-dimensional dendritic structure as an intermediate and maintains this three-dimensional dendritic structure. Some proposals have been made before.

For example, Patent Document 1 describes a step of preparing a solution containing a metal or a metal salt, a step of blowing acetylene gas into the solution to generate a dendritic carbon nanostructure made of metal acetylide, and the carbon nanostructure. A step of producing a metal-encapsulated dendritic carbon nanostructure in which a metal is encapsulated in the dendritic carbon nanostructure by heating the body at 60 to 80 ° C., and 160 of this metal-encapsulated dendritic carbon nanostructure. A step of producing a dendritic carbon mesoporous structure by heating to ~ 200 ° C. to eject metal, and a step of heating this carbon mesoporous structure to 1600 to 2200 ° C. under a reduced pressure atmosphere or an inert gas atmosphere. A porous carbon material prepared by a manufacturing method consisting of a pore diameter of 1 to 20 nm and an integrated pore volume of 0.2 to 1.5 cc / g obtained by analyzing nitrogen adsorption isotherms by the Dollimore-Heal method. A catalyst carrier that has a BET specific surface area of 200 to 1300 m ² / g, has a low rate of decrease in the amount of current over a long period of time, and can prepare a catalyst for solid polymer fuel cells with excellent durability. Carbon materials for mesoporous materials have been proposed.

Further, in Patent Document 2, an acetylide production step of blowing acetylene gas into an ammoniacal aqueous solution containing a metal or a metal salt to generate a metal acetylide, and a step of heating the metal acetylide at a temperature of 60 to 80 ° C. to generate metal particles. In the first heat treatment step of preparing the inclusion intermediate, the metal particle inclusion intermediate is heated at a temperature of 120 to 200 ° C. and the metal particles are ejected from the metal particle inclusion intermediate to obtain a carbon material intermediate. A second heat treatment step, a cleaning treatment step of contacting the carbon material intermediate with hot concentrated sulfuric acid to clean the carbon material intermediate, and a further cleaned carbon material intermediate at 1000 to 2100 ° C. A porous carbon material prepared by a production method comprising a third heat treatment step of heat-treating to obtain a carrier carbon material, which has a predetermined hydrogen content and a BET specific surface area of 600 to 1500 m ² / g. , And the relative intensity ratio (l _G ) of the peak intensity (l _D ) in the D-band 1200 to 1400 cm ^-1 range and the peak intensity (l ^{G) in the G-band 1500 to 1700 cm -1} obtained from the Raman spectral spectrum. _{A carrier carbon material having D} / l _G ) 1.0 to 2.0 and capable of preparing a catalyst for a solid polymer fuel cell capable of exhibiting high battery performance under high humidification conditions has been proposed.

Further, in Patent Document 3, an acetylide production step of blowing acetylene gas into an ammoniacal aqueous solution containing a metal or a metal salt to generate a metal acetylide, and a step of heating the metal acetylide at a temperature of 40 to 80 ° C. to generate metal particles. In the first heat treatment step of preparing the inclusion intermediate, the metal particle inclusion intermediate is compactally molded, and the obtained molded body is heated to 400 ° C. or higher at a heating rate of 100 ° C. or higher per minute to obtain this metal. A second heat treatment step of ejecting metal particles from the particle inclusion intermediate to obtain a carbon material intermediate, and contacting the carbon material intermediate with hot concentrated nitric acid or hot concentrated sulfuric acid to purify the carbon material intermediate. A third heat treatment step of heat-treating the purified carbon material intermediate at 1400 to 2100 ° C. in a vacuum or an inert gas atmosphere to obtain a carrier carbon material. a porous carbon material prepared, the specific surface area S _a is 600~1600m ² / g mesopore pore diameter 2~50nm obtained by analyzing the nitrogen adsorption isotherm of adsorption process in Dollimore-Heal method The relative intensity ratio ( _{l G} ) between the peak intensity in the range of G'-band 2650 to 2700 cm ^-1 and the peak intensity in the range of ^{G-band 1550 to 1650 cm -1} in the Raman spectral spectrum (l _G'). l _G' / l _{G ) is 0.8 to 2.2, and the specific pore area S 2-10} of the mesopores with a pore diameter of 2 nm or more and less than 10 nm is 400 to 1100 m ² / g. The specific pore volume V _{2-10 is 0.4 to 1.6 cc / g, and the specific pore area S 10-50} of the mesopores with a pore diameter of 10 nm or more and 50 nm or less is 20 to 20. The pores are 150 m ² / g, the specific surface area V _2-10 is 0.4 to 1.6 cc / g, and the nitrogen adsorption isotherm in the adsorption process is analyzed by the Horvath-Kawazoe method. _{A solid polymer fuel cell having a specific surface area S 2} of pores with a diameter of less than 2 nm of 250 to 550 m ² / g and capable of exhibiting excellent durability against potential fluctuations while maintaining high power generation performance. A carbon material for a catalyst carrier capable of preparing a catalyst for use has been proposed.

Furthermore, in Patent Document 4, a porous carbon material having a dendritic carbon nanostructure prepared through a self-decomposition explosion reaction using a metal acetylide as an intermediate [trade name: ESCARBON manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.] ( A carbon material for a catalyst carrier obtained by performing a graphitization treatment using [registered trademark) -MCND] as a raw material and then further performing an oxidation treatment using hydrogen peroxide, nitric acid, a submerged plasma apparatus, or the like. _{O ICP} content O _{ICP is 0.1 to 3.0% by mass, residual oxygen content O 1200 ° C.} remaining after heat treatment at 1200 ° C. in an inert gas (or vacuum) atmosphere is 0.1 to 1.5% by mass, BET specific surface area is 300 to 1500 m ² / g, half-value width ΔG of G-band detected in the range of 1550 to 1650 cm ^{-1 of Raman spectral spectrum is 30 to 70 cm -1} , and in an inert gas (or vacuum) atmosphere. The residual amount of hydrogen remaining after heat treatment at 1200 ° C. H _{1200 ° C.} is 0.005 to 0.080 mass%, which is excellent in durability against repeated load fluctuations such as start and stop, and under operating conditions under low humidification. A carbon material for a catalyst carrier has been proposed, which can prepare a catalyst for a polymer electrolyte fuel cell excellent in power generation performance.

WO 2014/129597 A1 Gazette WO 2015/088025 A1 Gazette WO 2015/141810 A1 Gazette WO 2016/133132 A1 Gazette

The carbon materials for catalyst carriers described in Patent Documents 1 to 4 above have a relatively large specific surface area and mesopore volume, and are also excellent in durability, and thus are particularly durable fuels for automobiles. Although it has excellent large current characteristics that are important for drawing out a large output when used as a battery, the inventors of the present application continued to study in more detail and found that the large current while maintaining durability. It was found that there is room for further improvement in enhancing the characteristics.
Then, in order to enhance this large current characteristic, as described above, a relatively large specific surface area and mesopore volume are required to support the catalyst metal platinum in a sufficiently and highly dispersed state on the catalyst carrier. In addition to this, it is important that the reaction gas has excellent diffusivity. It is considered that the cause of the overvoltage generated at the time of a large current is the movement resistance (diffusion resistance) of the substance involved in the positive electrode reaction. The specific substances involved in the transfer resistance are electrons, protons, oxygen, and the water vapor generated, but the electrons move through the carrier carbon material, exhibiting ohmic resistance behavior, and increasing the resistance due to the large current. It is considered that it will not be given. Protons move through a proton conductive resin, and as long as the degree of wetting is constant, they show ohmic resistance like electrons, and there is no special overvoltage increase at the time of large current. For this reason, it is generally accepted that the main cause of overvoltage at high currents is the diffusion of oxygen and water vapor. In order to improve the diffusion of oxygen and water vapor, it may correlate with the bulk density of the carbon material for the catalyst carrier from the viewpoint of improving the diffusivity of oxygen and water vapor in the porous carbon pores. I came up with the idea.

That is, the bulk density in the porous carbon material represents the degree of development of the pore structure, but when the micro to mesopore volumes are the same, by making this as low as possible, the macropore volume, that is, the tree It was speculated that it would be a porous carbon material with a well-developed shape structure, which led to the idea that the diffusibility of the reaction gas could be improved, and as a result, the high-current characteristics could be improved.
In this regard, the inventors of the present application have examined in Patent Document 3 that the thickness of a branch having a three-dimensional dendritic structure is increased by increasing the acetylene concentration in the process of producing metal acetylide, which is a raw material for a porous carbon material. A porous carbon capable of reducing ΔG without impairing the DBP oil absorption amount and the BET specific surface area, which indicate the degree of the dendritic network, by appropriately increasing the length and length is disclosed, and is described in Patent Documents 1 to 4 above. For such conventional carbon materials for catalyst carriers, an oxidizing acid solution containing (concentrated) nitric acid or hot concentrated sulfuric acid is used in the process of dissolving and removing silver particles in the process of obtaining the carbon material. However, by removing silver with such an oxidizing acid, not a little carbon oxidation occurs. Oxidation of carbon imparts functional groups such as hydroxyl groups and carboxyl groups to the surface of the particles. Since such a surface functional group causes a dehydration condensation reaction in the subsequent heat treatment at about 2000 ° C., it causes sintering of particles, whereby in the conventional carbon material for a catalyst carrier, the carbon material for a catalyst carrier is used. It turned out that there was a problem that the bulk density could not be significantly reduced.

Then, when the inventors of the present application examined such problems of the prior art in more detail, they have been treated with an acid solution from the viewpoint that silver is easily vaporized at a high temperature under reduced pressure. By drastically changing the silver removal (cleaning step) and heating at a predetermined temperature in a reduced pressure atmosphere, the functional groups on the particle surface can be removed without going through the silver removal step with an oxidizing acid. Sintering of particles in addition and subsequent high temperature treatment can be prevented, the bulk density is lower than that of the conventional carbon material for catalyst carriers, the gas diffusibility is good, and the power generation characteristics are the conventional carbon materials for catalyst carriers. We have found that there is an advantage that it is better than the one using the above, and have completed the present invention.

The present invention has been invented based on the above-mentioned findings, and its purpose is to have a lower bulk density than a conventional carbon material for a catalyst carrier, develop a dendritic structure, and make gas diffusible. In manufacturing catalysts for polymer electrolyte fuel cells that are excellent in power generation characteristics and also excellent in characteristics (specific surface area, mesopore volume, durability, etc.) required for use as fuel cells. It is an object of the present invention to provide a suitable carbon material for a catalyst carrier.
Furthermore, another object of the present invention is to provide a method for producing a carbon material for a catalyst carrier, which is useful for producing a catalyst for such a polymer electrolyte fuel cell.

That is, the present invention is as follows.
[1] A carbon material for a catalyst carrier of a polymer electrolyte fuel cell, which is a porous carbon material and which simultaneously satisfies the following (1), (2), and (3).
(1) The bulk density is 0.05 g / mL or more and less than 0.14 g / mL.
(2) The BET specific surface area determined by BET analysis of the nitrogen gas adsorption isotherm is 400 to 1500 m ² / g.
_{(3) The integrated pore volume V 2-10} with a pore diameter of 2 to 10 nm determined by analysis of the nitrogen gas adsorption isotherm using the Dollimore-Heal method is 0.4 to 1.5 mL / g.
[2] half-width ΔG of G- bands detected in the range of 1550～1650Cm ^-1 Raman spectroscopy spectrum, the polymer electrolyte fuel according to characterized in that it is a 50 to 70 cm ^-1 (1) Carbon material for catalyst carriers of batteries.
[3] The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to [1] or [2], _{wherein V 2-10 is 0.5 to 1.0 mL / g.}
[4] The catalyst carrier of the polymer electrolyte fuel cell according to any one of [1] to [3], wherein the mode diameter of the mesopores required in the nitrogen gas adsorption measurement is more than 2 nm and less than 9 nm. For carbon material.
[5] The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of [1] to [4], wherein the bulk density is 0.05 g / mL or more and 0.10 g / mL or less.
[6] For a catalyst carrier of a polymer electrolyte fuel cell according to any one of [1] to [5], wherein the rod-shaped body or the annular body has a three-dimensional dendritic structure branched three-dimensionally. Carbon material.
[7] A catalyst carrier for a polymer electrolyte fuel cell using the carbon material for a catalyst carrier according to any one of [1] to [6].

[8] The method for producing a carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of [1] to [6].
A silver acetylide production step of injecting acetylene gas into a reaction solution consisting of an aqueous ammonia solution of silver nitrate to synthesize silver acetylide, a decomposition step of self-decomposing and exploding the silver acetylide to obtain a decomposition product, and the decomposition product. A cleaning step of obtaining a carbon material intermediate from which silver has been removed by heat treatment at a temperature of 1400 to 1800 ° C. in a reduced pressure atmosphere, and a cleaning step in which the carbon material intermediate is placed in a vacuum or in an inert gas atmosphere at 1800 to 2200 ° C. A method for producing a carbon material for a catalyst carrier of a solid polymer fuel cell, which comprises a heat treatment step of obtaining a carbon material for a catalyst carrier by heat treatment at the same temperature as above.

According to the present invention, it is possible to provide a carbon material for a catalyst carrier having a low bulk density, excellent gas diffusibility, and high oxidation resistance and a high specific surface area. Further, by using these carbon materials for catalyst carriers as catalyst carriers for fuel cells, high catalytic activity can be imparted.
Further, according to the production method of the present invention, it is useful for producing a catalyst for a polymer electrolyte fuel cell, and carbon for a catalyst carrier having a low bulk density, excellent gas diffusivity, and high oxidation resistance and a high specific surface area. A method of manufacturing a material can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Manufacturing method of carbon material for catalyst carrier>
First, a method for producing a carbon material for a catalyst carrier according to an embodiment of the present invention will be described. The method for producing a carbon material for a catalyst carrier according to the present embodiment is a silver acetylide production step for obtaining silver acetylide, and decomposition by heating the silver acetylide to obtain a decomposition product composed of a composite material of silver and carbon. A cleaning step of treating the decomposition product composed of the composite material at a temperature of 1400 ° C. or higher and 1800 ° C. or lower in a reduced pressure atmosphere to remove silver from the composite material to obtain a carbon material intermediate. It has a heat treatment step of further heat-treating the carbon material intermediate in a state where silver has been removed to obtain a carbon material for a porous catalyst carrier. Hereinafter, each step will be described in detail.

(Silver acetylide production process)
The silver acetylide production step is not particularly limited as long as it is a known method, but for example, a method of producing silver acetylide by contacting an acetylene molecule with an aqueous silver nitrate solution described in Patent Document 1 can be used.

The method of contacting the acetylene gas is not particularly limited, and examples thereof include a method of passing the acetylene gas through the silver nitrate aqueous solution, and more specifically, a method of blowing the acetylene gas into the silver nitrate aqueous solution.

It is also possible to irradiate the silver nitrate aqueous solution with ultrasonic waves at the time of contact between the silver nitrate aqueous solution and the acetylene gas. This has the effect of promoting the dissolution and dispersion of acetylene gas in the silver nitrate aqueous solution.

Further, it is preferable to stir the silver nitrate aqueous solution at the time of contact between the silver nitrate aqueous solution and the acetylene gas. As a result, the frequency of contact between the acetylene gas and the silver nitrate aqueous solution increases, and as a result, silver acetylide is efficiently produced. Stirring may be performed using a general stirring blade or a stirrer such as a magnetic stirrer.

From the above, silver acetylide can be obtained as a bulky precipitate of white crystals.

(Disassembly process)
Next, the obtained silver acetylide is decomposed by heating to obtain a decomposition product composed of a composite material. By heating the silver acetylide, the silver acetylide explodes on a nanoscale and phase-separates into silver and carbon, at which time the silver forms nano-sized particles or is gasified by the heat of reaction to the surface. Squirt. Carbon has a highly aromatic structure because three acetylene compounds such as acetylene molecules easily gather to form a benzene ring. Further, since silver forms nanoparticles, the carbon phase from which silver has been removed becomes a porous structure.

Heating of silver acetylide can be performed, for example, as follows. The obtained silver acetylide precipitate remains in the silver acetylide by heating it in a reduced pressure atmosphere at, for example, 40 ° C. or higher and 100 ° C. or lower (this is referred to as "first heat treatment"). The solvent in the reaction solution can be removed, the heat energy of the explosion can be prevented from being spent on the heat of the phase transition of the solvent to the gas phase, and the decomposition of silver acetylide can be made efficient. At this temperature, silver acetylide does not decompose.

Next, the solvent-removed silver acetylide is heated at, for example, 150 ° C. or higher and 400 ° C. or lower (this is referred to as "second heat treatment"). By heating silver acetylide to such a relatively high temperature, silver acetylide explodes and decomposes on a nanoscale, and silver and carbon each form nanostructures. This gives a decomposition product of a composite material containing silver and carbon. The basic structure of the carbon phase portion of the composite material is mainly composed of several layers of graphene by forming polycyclic aromatic compounds with acetylene compounds as described above. Further, in the composite material, since silver forms nanoscale particles in the explosion process, the carbon material from which the silver particles have been removed can be obtained as a carbon material having a large specific surface area and a high porosity. ..

[Cleaning process (silver removal process)]
Next, the decomposition product made of the obtained composite material is heat-treated at a temperature of 1400 ° C. or higher and 1800 ° C. or lower under a reduced pressure atmosphere (this is referred to as a "third heat treatment". ), Vaporize and remove at least part of the metal from the composite.

By performing such a third heat treatment, silver is efficiently and sufficiently removed from the composite material. That is, since the vapor pressure of silver is relatively high in the above temperature range, the silver exposed on the carbon surface is easily vaporized and removed from the composite material. On the other hand, within the above temperature range, the carbon material, which is the main component of the composite material, undergoes structural changes due to heat, specifically, the graphene size becomes enormous due to the bonding between graphenes, and the graphene laminated structure develops. A structural change has occurred, and as a result of the structural deformation, the silver contained in the composite material is exposed on the surface of the composite material. As a result, silver as contained in the composite material before the third heat treatment can be vaporized and removed from the composite material. Since silver is removed, the material after removing silver becomes a carbon material essentially composed of carbon, which is referred to as a carbon material intermediate in the present invention.

By adopting this step, it is possible to prevent the problem that the metal cannot be sufficiently removed, which has been partially confirmed in the conventional cleaning treatment with nitric acid, hot concentrated sulfuric acid, or the like.

Further, as described above, in the conventional cleaning treatment with nitric acid, hot concentrated sulfuric acid, etc., the carbon is oxidized by the cleaning treatment, and functional groups such as hydroxyl groups and carboxyl groups are added to the surface of the carbon particles. In the subsequent heat treatment step described later, the bulk density of the obtained carbon material for a catalyst carrier tended to increase due to the sintering of particles caused when the added functional group caused a dehydration condensation reaction. However, it was found that this can be prevented by changing to this process.

The elemental components derived from silver acetylide remaining in the carbon material intermediate obtained through this step can be analyzed by a known measurement method. For example, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma emission spectrometry (ICP-AES), atomic absorption spectrometry (AAS) and the like can be mentioned. Here, the amount of silver derived from silver acetylide remaining in the carbon material intermediate obtained through this step is preferably, for example, less than 1000 ppm, more preferably less than 500 ppm, and even more preferably not detected. .. If a large amount of silver remains, the remaining silver may adversely affect the application characteristics depending on the use of the carbon material for the catalyst carrier. In addition, there is a risk that the remaining silver will volatilize in the subsequent heat treatment step and contaminate or damage the equipment such as the heating furnace.

Further, as described above, the temperature in this step is 1400 ° C. or higher and 1800 ° C. or lower. When the temperature in this step is less than the above lower limit, the vapor pressure of silver is not sufficiently high even if the degree of vacuum is improved, and the silver removal efficiency is not sufficient. On the other hand, when the temperature in this step exceeds the above upper limit, graphitization is promoted in the heat treatment step described later due to the graphitization catalytic action of silver present in the carbon material intermediate after the treatment, and the bulk density increases. There is a risk.

The time in this step is not particularly limited, but is, for example, 10 minutes or more and 20 hours or less, preferably 30 minutes or more and 10 hours or less. As a result, the metal can be sufficiently removed, unintentional excessive carbonization and crystallization can be prevented, and the quality of the finally obtained porous carbon material can be more easily controlled.

The pressure in this step is not particularly limited, but in this step, for example, the treatment is performed in a reduced pressure atmosphere of 0.1 Pa or more and 10000 Pa or less, preferably 1 Pa or more and 5000 Pa or less, and more preferably 1 Pa or more and 1000 Pa or less. Is done. By keeping the pressure of the atmosphere low, the metal can be removed efficiently.

(Heat treatment process)
Next, the carbon material intermediate in which silver has been removed is heat-treated to obtain a porous carbon material for a catalyst carrier (this is referred to as a "fourth heat treatment"). Crystals of the porous carbon material can be developed by the heat treatment performed in this step, and the crystallinity can be adjusted and controlled by the temperature. For example, when used as a catalyst carrier for electrodes of polymer electrolyte fuel cells, the porous carbon material has a relatively high temperature, for example, about 80 ° C., is strongly acidic with a pH of 1 or less, and has 1.3 V vs. SHE. It is exposed to a high potential environment, and in such an environment, carbon in the porous carbon material is easily oxidatively consumed. Therefore, when the porous carbon material is used as a catalyst carrier, it is important to enhance the crystallinity in this step.

By the way, the pores and the specific surface area in the porous carbon material are factors that greatly affect the supported amount of the catalyst when used as a catalyst carrier. Therefore, the porous carbon material has many pores and the specific surface area. Is generally preferred. However, it is generally said that when a porous carbon material is heat-treated, crystals develop while the pores are crushed and the specific surface area of the material decreases.

From such a viewpoint, the temperature of the heat treatment in this step is preferably 1800 ° C. or higher and 2200 ° C. or lower. As a result, it is possible to prevent a decrease in the specific surface area and sufficiently increase the crystallinity of the porous carbon material without increasing the bulk density.

The heat treatment in this step is not particularly limited, but can be performed, for example, in a reduced pressure atmosphere or an inert gas atmosphere, preferably under an inert gas atmosphere. The inert gas is not particularly limited, but for example, nitrogen, argon or the like can be used.
In addition, this step can be performed using a general heating furnace. Further, this step may be continued from the above-mentioned step of removing silver.

In the method for producing a porous carbon material according to the present embodiment described above, by adopting the removal step as described above, silver particles can be efficiently and sufficiently removed from the composite material, and the obtained carbon for a catalyst carrier can be obtained. It is possible to reduce the bulk density of the material.

<Carbon material for catalyst carrier>
Next, the porous carbon material for a catalyst carrier obtained by the present invention will be described.
The carbon material for a catalyst carrier produced by the above method is formed by ejecting silver from a bulky precipitate of silver acetylide as a raw material. Therefore, the carbon material for the catalyst carrier is a porous body having a large number of ejection holes (mesopores). Due to the presence of such a mesopore, it has a relatively large specific surface area, and for example, a catalyst or the like can be supported on the surface.

Further, the microscopic structure of the carbon material for the catalyst carrier may differ depending on the type of metal acetylide, that is, the type of metal used for forming the metal acetylide.

When the carbon material for the catalyst carrier is derived from silver acetylide, it has a dendritic carbon mesoporous structure having a three-dimensional structure in which a rod-shaped body or an annular body containing carbon is branched three-dimensionally. More specifically, this carbon mesoporous structure has a so-called dendrite-like three-dimensional structure in which rod-shaped or annular bodies are three-dimensionally extended and bonded to each other to form a network. There is.

Further, the carbon mesoporous structure is generally composed of an epidermis made of graphene and carbon particles such as a plurality of graphene sachets contained therein, depending on the production method or the like. Here, "graphene" is a hexagonal network of carbon atoms, which corresponds to a single layer of graphite.

Since the carbon mesoporous structure has the dendritic portion as described above, it has a high specific surface area by itself. Therefore, any gas such as hydrogen can be sufficiently occluded, and it can sufficiently function as a gas molecule occluder. In addition, it can sufficiently function as a catalyst-supporting carrier.

Here, it is generally said that if the bulk density of the porous carbon material is 0.10 g / mL or less, it may be difficult to secure the specific surface area and the carbon wall strength at the same time. As for the carbon material, as described above, since it is composed of a graphene skin and carbon particles such as a plurality of graphene sachets contained therein, the carbon wall has a bulk density of less than 0.10 g / mL. It has been confirmed from cross-sectional photographs and the like of a solid polymer fuel cell catalyst layer using the porous carbon material that the strength can be maintained. However, even with the carbon material for a catalyst carrier of the present invention, if the bulk density is less than 0.05 g / mL, it may be difficult to maintain the strength of the carbon wall. On the other hand, when the bulk density is 0.14 g / mL or more, it can be considered that the particles are sintered in the process of manufacturing the carbon material for the catalyst carrier, and the gaps in the dendritic structure are reduced. It is presumed that, for example, when it is used as a member of a polymer electrolyte fuel cell, the gas diffusivity is lowered.

As for the catalyst carrier carbon material for the present invention, the above (2) as, BET specific surface area as determined by BET analysis of nitrogen sorption isotherms 400~1500m ² / g, preferably 500 meters ² / g or more 1400m ^When it is necessary to be 2 / g or less and the BET specific surface area is 400 m ² / g or more, preferably 500 m ² / g or more, the catalyst metal particles of several nm are in a well-dispersed state, that is, , The catalyst metal particles are supported in a state where the distance between them is maintained at a certain value or more and the particles can exist independently. On the contrary, if the BET specific surface area is ^{less than 400 m 2} / g, the distance between the catalyst particles may be shortened, and it may be difficult to support the catalyst metal fine particles with high density and uniformly. As a result, the catalyst metal particles are effective. The area is reduced and the fuel cell characteristics are significantly reduced. Further, ^{if the size is increased to exceed 1500 m 2} / g, the edge portion of the porous carbon material is increased, so that the durability may be easily lowered with a substantial decrease in crystallinity.

Further, as described in (3) above, such a carbon material for a catalyst carrier of the present invention has an integrated pore volume V having a pore diameter of 2 to 10 nm, which is obtained by analysis of nitrogen gas adsorption isotherms using the Dollimore-Heal method. _{It is necessary that 2-10} is 0.4 to 1.5 mL / g, preferably 0.5 to 1.0 mL / g. By having such a pore diameter of 2 to 10 nm, the catalyst metal fine particles usually prepared to have a diameter of several nm are dispersed in the pores in a highly dispersed state, which preferably contributes from the viewpoint of the catalyst utilization rate. When the pore volume V _2-10 is less than 0.4 mL / g, the volume is small with respect to the pore area, so that the average pore size is small. When platinum fine particles, which are catalyst metals, are supported in the pores, the voids between the pores and the platinum fine particles become small, so that gas diffusion may decrease and the large current characteristics may decrease. On the contrary, when V _2-10 becomes larger than 1.5 mL / g, the skeleton as a carbon material for a carrier becomes thin, the oxidation consumption resistance is lowered, and the catalyst layer for preparing a catalyst layer is prepared. The skeleton of the carbon material for the carrier may be easily destroyed by the stirring required in the preparation of the ink solution, and the characteristics derived from the shape may not be exhibited.

Further, the most frequent diameter of the pore distribution of the mesopores derived from the carrier (also simply referred to as "mode (straight) diameter of the mesopores" in the present invention) is preferably more than 2 nm and less than 9 nm, more preferably. Is 2.1 to 5 nm or less. Since the general particle size of the catalyst particles used in the polymer electrolyte fuel cell is about 2 nm, the mesopores on which the catalyst particles are supported are preferably larger than 2 nm. On the other hand, when the mode diameter of the mesopores is as large as 9 nm or more, pores that are excessively larger than the catalyst particles are present, and the presence of unnecessary spaces causes a decrease in catalyst loading efficiency, resulting in a decrease in initial power generation characteristics. Invite.

Further, with respect to the carbon material for a catalyst carrier of the present invention, G detected in the range ^{of 1550 to 1650 cm -1} of the Raman spectral spectrum is detected from the viewpoint of enhancing the crystallinity and improving the durability in the environment in which the fuel cell is used. - half width ΔG band is preferably 50 to 70 cm ^-1, more preferably in the range of 50~65cm ^-1. This ΔG is said to represent the extent of the carbon network surface of the carbon material, and if ΔG is ^{less than 50 cm -1} , the carbon network surface expands too much and the amount of edges of the carbon network surface forming the pore wall decreases. The supporting property of the catalyst metal fine particles on the pore wall tends to decrease, and conversely, when ^{the size exceeds 70 cm -1} , the carbon network surface becomes narrow and the edge amount of the carbon network surface, which is easily oxidatively consumed, increases, so that it is durable. The sex tends to decrease.

As described above, the carbon material for a catalyst carrier of the present invention preferably comprises a dendritic carbon nanostructure having a three-dimensional dendritic structure in which a rod-shaped body or an annular body is three-dimensionally branched as a catalyst carrier. Not only is it equivalent or better in BET specific surface area and durability compared to conventional dendritic carbon nanostructures of this type, but as mentioned above, it has a lower bulk density, which results in better gas diffusivity. Since it has a high specific surface area with high oxidation resistance, the reaction gas is diffused into the catalyst layer prepared using this carbon material as a catalyst carrier without resistance, and the water (generated water) generated in this catalyst layer is delayed. It is possible to obtain a solid polymer fuel cell having excellent durability as a fuel cell, in which mesopores suitable for discharging the catalyst metal are formed, and the utilization rate of the catalyst metal is less likely to decrease. it can.

Hereinafter, the carbon material for the catalyst carrier of the present invention will be specifically described with reference to Examples. The examples shown below are merely examples of the present invention, and the present invention is not limited to the following examples.

1. 1. Production of carbon material for catalyst carrier <Example 1>
(I-1) Silver acetylide production step A 1.9 mass% ammonia aqueous solution containing silver nitrate at a concentration of 15.6 mass% is prepared in a flask, and after removing residual oxygen with an inert gas such as argon or dry nitrogen, the residue is removed. While stirring the solution and immersing the ultrasonic transducer in the liquid to give vibration, acetylene gas was sprayed on 150 mL of the solution at a flow rate of 25 mL / min for about 4 minutes. As a result, a solid substance of silver acetylide was formed in the solution and started to precipitate. The precipitate was then filtered through a membrane filter, and upon filtration, the precipitate was washed with methanol, some methanol was added, and the precipitate was impregnated with methanol.

(I-2) Decomposition step of silver acetylide 1 g of the above-mentioned precipitate impregnated with methanol is placed in a test tube and held in a vacuum dryer at 30 to 40 ° C. for 1 hour to remove methanol. After that (first heat treatment), the mixture was continuously heated to a temperature of 160 ° C. to 200 ° C. for 20 minutes (second heat treatment). Here, a nanoscale explosive reaction occurred in the test tube, the contained silver was ejected, and a large number of ejection holes were formed on the surface and inside. As a result, a decomposition product composed of a composite material containing silver and carbon as a silver-encapsulated nanostructure was obtained.

(I-3) Purification Step 25 g of the composite material containing silver and carbon obtained by the above (i-2) decomposition step of silver acetylide is weighed and placed in a graphite crucible, and the temperature is raised to 3000 ° C. in an argon atmosphere. After vacuum replacement with argon gas in a possible Tanman furnace, the pressure was reduced to 0.5 Pa and the temperature was raised to 1400 ° C. at 15 ° C./min. Then, after reaching a predetermined temperature, the temperature was maintained for 10 hours to remove silver to obtain a purified carbon material intermediate from which silver had been removed (third heat treatment).

(I-4) Heat Treatment Step The purified carbon material intermediate obtained by the cleaning step of (i-3) above was heated to 2100 ° C. at 15 ° C./min under argon flow. Then, after reaching a predetermined temperature, the temperature was maintained for 2 hours and heat treatment was performed (fourth heat treatment) to obtain a porous carbon material for a catalyst carrier according to Example 1. As the graphite material for the crucible, a graphite crucible having a low density and a large graphite particle size as an aggregate was extruded and molded so that the density of the molded product did not increase.
<Example 2>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 2000 ° C.

<Example 3>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 1900 ° C.

<Example 4>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 1800 ° C.

<Example 5>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1600 ° C.

<Example 6>
Examples except that the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1600 ° C. and the maintenance temperature of the heat treatment step after silver removal (fourth heat treatment) was set to 1800 ° C. A carbon material for a catalyst carrier was obtained in the same procedure as in 1.

<Example 7>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 2200 ° C.

<Comparative example 1>
(Ii-1) Acid removal step 1
Using 20 g of a composite material (decomposition product) containing silver and carbon obtained by performing the above-mentioned (i-2) decomposition step of silver acetylide in Example 1, this is immersed in 1500 g of 30 mass% concentrated nitric acid. , 60 ° C. for 24 hours. The composite and concentrated nitric acid were then separated using a centrifuge. For the purpose of removing nitric acid adhering to the composite material, the separated composite material was dispersed in pure water again, and the composite material (solid) was separated from the liquid by a centrifuge. Nitric acid was removed by performing this washing operation twice. Then, moisture was removed by treatment in air at 140 ° C. for 2 hours to dry the mixture, and then heat treatment was performed at 1100 ° C. for 2 hours under argon flow.

(Ii-2) Acid removal step 2
8 g of the silver-carbon-containing composite material obtained in the acid removal step 1 of (ii-1) above was immersed in 150 g of 30 mass% concentrated nitric acid and washed at 60 ° C. for 24 hours. The composite material and concentrated nitric acid were then separated using a centrifuge. For the purpose of removing nitric acid adhering to the composite material, the separated composite material was dispersed in pure water again, and the composite material (solid) was separated from the liquid by a centrifuge. Nitric acid was removed by performing this washing operation twice. Then, the composite material was treated in air at 140 ° C. for 2 hours to remove water and dried, and then heat-treated at 1400 ° C. for 2 hours under argon flow.

(Ii-3) Heat Treatment Step 6 g of the composite material obtained in the above (ii-2) Acid Removal Step 2 was heated to 2100 ° C. at 15 ° C./min under argon flow. Then, after reaching a predetermined temperature, the temperature was maintained for 2 hours and heat treatment was performed (fourth heat treatment) to obtain a porous carbon material for a catalyst carrier according to Comparative Example 1.

<Comparative example 2>
A carbon material for a catalyst carrier was obtained in the same procedure as in Comparative Example 1 except that the maintenance temperature in the heat treatment step (fourth heat treatment) was set to 1800 ° C.

<Comparative example 3>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 1500 ° C.

<Comparative example 4>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 1400 ° C.

<Comparative example 5>
Examples except that the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1600 ° C. and the maintenance temperature of the heat treatment step after silver removal (fourth heat treatment) was set to 1500 ° C. A carbon material for a catalyst carrier was obtained in the same procedure as in 1.

<Comparative Example 6>
Examples except that the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1600 ° C. and the maintenance temperature of the heat treatment step after silver removal (fourth heat treatment) was set to 1300 ° C. A carbon material for a catalyst carrier was obtained in the same procedure as in 1.

<Comparative Example 7>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 2300 ° C.

<Comparative Example 8>
A carbon material for a catalyst carrier was obtained in the same procedure as in Example 1 except that the maintenance temperature of the heat treatment step (fourth heat treatment) after silver removal was set to 2500 ° C.

<Comparative Example 9>
When the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1300 ° C., the determination of the amount of residual silver contained in the cleaned carbon intermediate was unsuccessful. Was not processed.

<Comparative Example 10>
When the maintenance temperature of the cleaning step (silver removal step, third heat treatment) was set to 1100 ° C., the determination of the amount of residual silver contained in the cleaned carbon intermediate was unsuccessful. Was not processed.

<Comparative Example 11>
5 g of Ketjen Black EC600JD (manufactured by Lion) was heated to 2100 ° C. at 15 ° C./min under argon flow. Then, after reaching a predetermined temperature, the temperature was maintained for 2 hours and heat treatment was performed (corresponding to the fourth heat treatment) to obtain a carbon material for a catalyst carrier.

<Comparative Example 12>
A carbon material for a catalyst carrier was obtained in the same procedure as in Comparative Example 11 except that the maintenance temperature of the heat treatment (corresponding to the fourth heat treatment) was set to 2000 ° C.

<Comparative Example 13>
A carbon material for a catalyst carrier was obtained in the same procedure as in Comparative Example 11 except that the maintenance temperature of the heat treatment (corresponding to the fourth heat treatment) was set to 1900 ° C.

2. Evaluation (i) Measurement of BET specific surface area, integrated pore volume V _{2-10 with} pore diameter 2 to 10 nm, and mode diameter Weigh about 30 mg of each of the carbon materials for catalyst carriers of Examples and Comparative Examples, and measure them at 150 ° C. After vacuum drying, the specific surface area was measured by the gas adsorption method using nitrogen gas using an automatic specific surface area measuring device (QUADRASORB evo manufactured by Cantachrome Instruments Japan), and the specific surface area was determined based on the BET analysis formula. .. The adsorption isotherm of the adsorption process was analyzed and calculated by the Dollimore-Hell method (DH method). _{The integrated pore volume V 2-10} (mL / g) and pore mode diameter (nm) of the mesopores with a pore diameter of 2 to 10 nm were calculated from the analysis program built into the device. The evaluation results are shown in Table 1.

^{(Ii) Half width ΔG (cm -1} ) of the G-band detected in the range of 1550 to 1650 cm ^{-1 of the Raman spectroscopic spectrum.}
The carbon material for the catalyst carrier prepared in each Example and Comparative Example was used as a sample, and after measuring about 3 mg of this, it was set in a laser Raman spectrophotometer (NRS-3100 type manufactured by JASCO Corporation), and the excitation laser: 532 nm, laser power: 10 mW (sample irradiation power: 1.1 mW), microscopic arrangement: Backscattering, slit: 100 μm × 100 μm, objective lens: × 100 times, spot diameter: 1 μm, exposure time: 30 sec, observed wave number: 2000 to 300 cm ^-1, and the accumulated number of times: 6 times measured under the measurement conditions, determine the half-width of the G- band called graphite appearing in each 1580 cm ^-1 vicinity of six spectra obtained .DELTA.G ^{(cm -1),} The average value was used as the measured value.

(Iii) Bulk Density About 300 mg of each of the carbon materials for catalyst carriers of each Example and Comparative Example was weighed and tapped 150 times using a tap denser (KYT-5000 manufactured by Seishin Enterprise Co., Ltd.) to measure the bulk density. The evaluation results are shown in Table 1.
(IV) Measurement of Residual Silver Amount Inductively coupled plasma emission to the residual amount of silver remaining in the cleaned carbon material intermediate after the cleaning step of each Example and Comparative Example or the carbon material intermediate after acid treatment 2. It was determined by spectroscopic analysis (ICP-AES). Those with a failure rank in this evaluation are in the heat treatment step (fourth heat treatment) because the residual silver may volatilize in the subsequent heat treatment step (fourth heat treatment) and damage the furnace body. Cannot be implemented.
[Pass rank]
◯: The residual amount of silver is below the detection limit to 1000 ppm or less [Failure rank]
X: Residual amount of silver exceeds 1000 ppm

<Catalyst preparation, catalyst layer preparation, MEA preparation, fuel cell assembly, and battery performance (durability) evaluation>
Next, using the carbon materials for each catalyst carrier prepared as described above, a catalyst for a solid polymer fuel cell in which a catalyst metal is supported is prepared as described below, and the obtained catalyst is used. The catalyst layer ink solution is prepared, then a catalyst layer is formed using this catalyst layer ink solution, and a membrane electrode junction (MEA: Membrane Electrode Assembly) is prepared using the further formed catalyst layer. The MEA was incorporated into a fuel cell, and a power generation test was conducted using a fuel cell measuring device. Hereinafter, the preparation of each member and the cell evaluation by the power generation test will be described in detail.

(1) Preparation of catalyst for polymer electrolyte fuel cell (platinum-supported carbon material) The carbon material for each catalyst carrier prepared above was dispersed in distilled water, formaldehyde was added to the dispersion, and the temperature was set to 40 ° C. The mixture was set in a water bath, and after the temperature of the dispersion became 40 ° C., which was the same as that of the bath, the dinitrodiamine Pt complex nitrate aqueous solution was slowly poured into the dispersion under stirring. Then, after continuing stirring for about 2 hours, it was filtered and the obtained solid matter was washed. The solid matter thus obtained is vacuum dried at 90 ° C., pulverized in a mortar, and then heat-treated at 200 ° C. for 1 hour in an argon atmosphere containing 5% by volume of hydrogen to prepare a carbon material supporting platinum catalyst particles. did. The amount of platinum supported by this platinum-supported carbon material was adjusted to be 25% by mass with respect to the total mass of the carbon material for the catalyst carrier and the platinum particles, and inductively coupled plasma emission spectroscopy (ICP-AES: Inductively). It was measured and confirmed by Coupled Plasma --Atomic Emission Spectrometry).

(2) Preparation of catalyst layer Using the platinum-supported carbon material (Pt catalyst) prepared as described above, and using Dupont's Nafion (registered trademark: Nafion; persulfonic acid-based ion exchange resin) as the electrolyte resin. In the Ar atmosphere, these Pt catalysts and Nafion were used at a ratio of 1.0 times the mass of the Nafion solid content to the mass of the platinum catalyst particle-supporting carbon material and 0.5 times the mass of the non-porous carbon. After blending and lightly stirring, the Pt catalyst was crushed with ultrasonic waves, and ethanol was further added to adjust the total solid content concentration of the Pt catalyst and the electrolyte resin to 1.0% by mass. A catalyst layer ink solution in which a Pt catalyst and an electrolyte resin were mixed was prepared.

Ethanol was further added to each catalyst layer ink liquid having a solid content concentration of 1.0% by mass thus prepared to prepare a catalyst layer ink liquid for spray coating having a platinum concentration of 0.5% by mass, and a platinum catalyst was prepared. The spray conditions were adjusted so that the mass per layer unit area (hereinafter referred to as "platinum grain amount") was 0.1 mg / cm ^2, and the catalyst layer ink for spray coating was applied onto a Teflon (registered trademark) sheet. After spraying, it was dried in argon at 120 ° C. for 60 minutes to prepare a catalyst layer.

(3) Preparation of MEA Using the catalyst layer prepared as described above, MEA (membrane electrode complex) was prepared by the following method.
A square electrolyte membrane with a side of 6 cm was cut out from the Nafion membrane (NR211 manufactured by DuPont). Further, each catalyst layer of the anode and the cathode coated on the Teflon (registered trademark) sheet was cut into a square shape having a side of 2.5 cm with a cutter knife.
The electrolyte membranes are sandwiched between the anode and cathode catalyst layers cut out in this way so that the respective catalyst layers are in contact with each other with the central portion of the electrolyte membrane sandwiched between them and are not displaced from each other. After pressing at / cm ² for 10 minutes and then cooling to room temperature, only the Teflon® sheet was carefully peeled off for both the anode and cathode, and the anode and cathode catalyst layers were fixed to the electrolyte membrane. An anode was prepared.

Next, as a gas diffusion layer, a pair of square carbon papers having a side size of 2.5 cm were cut out from carbon paper (35BC manufactured by SGL Carbon Co., Ltd.), and between these carbon papers, each catalyst layer of anode and cathode was cut out. The MEA was prepared by sandwiching the catalyst layer-electrolyte membrane conjugate and ^{pressing at 120 ° C. and 50 kg / cm 2} for 10 minutes so that the two were consistent and not misaligned.
Regarding the amount of each component of the catalyst metal component, carbon material, and electrolyte material in each MEA produced, the mass of the Teflon (registered trademark) sheet with a catalyst layer before pressing and the Teflon (registered trademark) peeled off after pressing. The mass of the catalyst layer fixed on the Nafion membrane (electrolyte membrane) was obtained from the difference from the mass of the sheet, and was calculated from the mass ratio of the composition of the catalyst layer.

(4) Evaluation of power generation performance of fuel cell Each MEA produced using the carbon material for each catalyst carrier according to each Example and Comparative Example is incorporated into a cell, set in a fuel cell measuring device, and fueled by the following procedure. The performance of the battery was evaluated.
Air is used as an oxidizing gas on the cathode side, and pure hydrogen is used as a reaction gas on the anode side. The pressure is adjusted by a back pressure valve provided downstream of the cell so that the utilization rates are 40% and 70%, respectively. , The back pressure was 0.1 MPa. The cell temperature is set to 80 ° C., and the oxidative gas and reaction gas to be supplied are bubbling with distilled water kept at 60 ° C. in a humidifier for both the cathode and the anode in a low humidification state. Power generation was evaluated.

Under the condition that the reaction gas was supplied to the cell under such a setting, the load was gradually increased, the ^{voltage between the cell terminals at a current density of 1000 mA / cm 2} was recorded as the output voltage, and the performance of the fuel cell was evaluated. , The evaluation was performed based on the following criteria of pass rank ○ and fail rank ×. The results are shown in Table 1.
[Pass rank]
◯: The output voltage at 1000 mA / cm ² is 0.65 V or more.
[Failure rank]
X: The output voltage at 1000mA / cm ² is less than 0.65V.

[Evaluation of durability]
In the above cell, the operation of setting the cell voltage to 1.0 V and holding it for 4 seconds and holding the cell voltage to 1.3 V for 4 seconds while flowing argon gas under the same humidifying conditions as above to the cathode while keeping the anode as it is. The operation of repeating the operation (repeating operation of the square wave voltage fluctuation) is set as one cycle, and after performing the repeating operation of the square wave voltage fluctuation for 200 cycles, the durability is improved in the same manner as the evaluation of the large current characteristic described above. The survey was conducted and evaluation was performed based on the following criteria of pass rank ○ and fail rank ×. The results are shown in Table 1.
[Pass rank]
◯: The output voltage at 1000 mA / cm ² is 0.65 V or more.
[Failure rank]
X: The output voltage at 1000mA / cm ² is less than 0.65V.

Claims (8)

A carbon material for a catalyst carrier of a polymer electrolyte fuel cell, which is a porous carbon material and is characterized by simultaneously satisfying the following (1), (2) and (3).
(1) The bulk density is 0.05 g / mL or more and less than 0.14 g / mL.
(2) The BET specific surface area determined by BET analysis of the nitrogen gas adsorption isotherm is 400 to 1500 m ² / g.
_{(3) The integrated pore volume V 2-10} with a pore diameter of 2 to 10 nm determined by analysis of the nitrogen gas adsorption isotherm using the Dollimore-Heal method is 0.4 to 1.5 mL / g. Half width ΔG of G- bands detected in the range of 1550～1650Cm ^-1 Raman spectroscopy spectrum, the polymer electrolyte fuel cell according to claim 1, characterized in that a 50 to 70 cm ^-1 catalyst Carbon material for carriers. The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to claim 1 or 2, wherein V _{2-10 is 0.5 to 1.0 mL / g.} The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of claims 1 to 3, wherein the mode diameter of the mesopores required in the nitrogen gas adsorption measurement is more than 2 nm and less than 9 nm. The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of claims 1 to 4, wherein the bulk density is 0.05 g / mL or more and 0.10 g / mL or less. The carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of claims 1 to 5, wherein the rod-shaped body or the annular body has a three-dimensional dendritic structure branched three-dimensionally. A catalyst carrier for a polymer electrolyte fuel cell using the carbon material for a catalyst carrier according to any one of claims 1 to 6. The method for producing a carbon material for a catalyst carrier of a polymer electrolyte fuel cell according to any one of claims 1 to 6.
A silver acetylide production step of injecting acetylene gas into a reaction solution consisting of an aqueous ammonia solution of silver nitrate to synthesize silver acetylide, a decomposition step of self-decomposing and exploding the silver acetylide to obtain a decomposition product, and the decomposition product. A cleaning step of obtaining a carbon material intermediate from which silver has been removed by heat treatment at a temperature of 1400 to 1800 ° C. in a reduced pressure atmosphere, and a cleaning step in which the carbon material intermediate is placed in a vacuum or in an inert gas atmosphere at 1800 to 2200 ° C. A method for producing a carbon material for a catalyst carrier of a solid polymer fuel cell, which comprises a heat treatment step of obtaining a carbon material for a catalyst carrier by heat treatment at the same temperature as above.