JP7715367B2 - Carbon-based support and method for preparing the same - Google Patents

Description

The present invention relates to a carbon-based support for supporting catalyst particles that constitute a catalyst layer component of a fuel cell, and a method for preparing the carbon-based support.

A fuel cell is a battery that generates electricity by supplying and reacting a negative electrode active material, such as hydrogen, with a positive electrode active material, such as oxygen from the air, to generate a potential difference between an electrode located on the supply side of the negative electrode active material (hereinafter also referred to as the hydrogen electrode) and an electrode located on the supply side of the positive electrode active material (hereinafter also referred to as the oxygen electrode). By continually replenishing these active materials, fuel cells have the advantage of being able to continuously extract electricity without any limitations on electrical capacity. Furthermore, the by-product of electricity generation is often mainly water, and they have attracted widespread attention from both economic and environmental perspectives.

One such type of fuel cell, the polymer electrolyte fuel cell, generally consists of a solid polymer membrane made of a proton-conducting polymer such as Nafion®, with catalyst layers formed on both sides. The solid polymer membrane with the catalyst layer formed is sandwiched between electrodes such as carbon paper to form a cell, and this cell is constructed either individually or by connecting (stacking) multiple cells in series or parallel.

Among the various components of a fuel cell, the catalyst layer is the site where electrons and protons are generated from the negative electrode active material and where the electrons and protons react with the positive electrode active material, and it plays an important role in the electricity-generating mechanism of the fuel cell.

One example of a catalyst layer configuration is one in which platinum carbon black, which is activated carbon black carrying platinum microparticles, is used as the catalyst layer constituent, and this is attached to both sides of an electrode or solid polymer membrane together with Nafion (registered trademark; hereafter simply referred to as "Nafion"), which has proton conductivity.

However, fuel cells using the above-mentioned conventional platinum carbon black as a catalyst layer component have the problem that, for example, in the catalyst layer on the oxygen electrode side, proton-conducting polymers such as Nafion are easily washed away due to moisture generated by electromotive force.

That is, protons generated at the hydrogen electrode reach the oxygen electrode side through the polymer electrolyte membrane, and react with molecular oxygen and electrons on the platinum surface via the proton-conducting polymer in the catalyst layer on the oxygen electrode side. However, due to the acidic functional groups in the proton-conducting polymer necessary for proton conduction, the proton-conducting polymer itself has high hydration properties. As the fuel cell operates, the proton-conducting polymer in the catalyst layer on the oxygen electrode side is washed away by the water produced by the reaction, causing the catalyst layer to deteriorate and resulting in a decrease in electromotive force.

In order to provide a catalyst layer structure that can prevent the loss of proton-conductive polymer from the catalyst layer even when moisture is generated during fuel cell operation, the inventors previously proposed a technology in which catalyst particles are supported on carbon via a support layer consisting of two layers, an upper and lower layer, and the upper layer of the support layer is formed from a polymer with proton conductivity, serving as a proton-conductive layer that conducts protons generated in the catalyst particles and protons to be supplied to the catalyst particles, while the lower layer of the support layer is formed from a polymer that has affinity for both the proton-conductive layer and carbon, and whose molecular structure contains a benzene ring and a basic structure, serving as an adhesive layer that bonds the proton-conductive layer to the carbon (see, for example, Patent Document 1).

In this way, the proton conductive layer is placed on the carbon via an adhesive layer, which minimizes the risk of the proton conductive layer being lost due to water, thereby suppressing deterioration of the catalyst layer and a decrease in electromotive force.

JP 2013-179030 A

As such, while the above-mentioned conventional technology provides an excellent catalyst layer structure, there is still room for improvement in terms of further improving electromotive performance.

In other words, with the above-mentioned conventional technology, when the catalyst surface is covered with a proton-conducting polymer, the amount of oxygen reaching the catalyst surface, particularly on the oxygen electrode side, is suppressed, preventing sufficient electromotive performance.

The present invention was made in consideration of these circumstances, and provides a carbon-based support that does not require covering the catalyst surface with a proton-conducting polymer, and can increase the amount of oxygen that reaches the catalyst surface, particularly on the oxygen electrode side.

The present invention also provides catalyst layer structures, catalyst-equipped electrodes, catalyst-equipped solid polymer membranes, cells, fuel cells, and methods for preparing carbon-based supports, each of which includes the above-mentioned carbon-based support, as well as their use as support layer constituent materials.

In order to solve the above-mentioned conventional problems, the carbon-based support according to the present invention provides: (1) a carbon-based support for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, the carbon-based support being represented by the following general formula [I]:
and a monolayer support layer made of sulfonic acid-modified polybenzimidazole, which is a block copolymer (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked to a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) .
The carbon-based support according to the present invention is (2) a carbon-based support for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, the carbon-based support being represented by the following general formula [II]:
The carbon was assumed to have a single support layer made of sulfonic acid-modified polybenzimidazole represented by the formula:

In addition, the catalyst layer structure according to the present invention is ( 3 ) formed by supporting metal catalyst particles on the surface of the carbon-based support described in (1) or (2) above.

In the catalyst-equipped electrode according to the present invention, the catalyst layer is formed by depositing the catalyst layer structure described in ( 4 ) and ( 3 ) on the surface of an electrode sheet.

In addition, the cell according to the present invention is provided with the catalyst-equipped electrode described in ( 5 ) and ( 4 ) as at least the oxygen electrode side electrode.

In the catalyst-containing solid polymer membrane according to the present invention, the catalyst layer is formed by depositing the catalyst layer construct described in ( 6 ) and ( 3 ) on at least the oxygen electrode side surface of the solid polymer membrane.

The cell according to the present invention is provided with the catalyst-attached solid polymer membrane described in ( 7 ) and ( 6 ).

The fuel cell according to the present invention includes the cell according to ( 8 ), ( 5 ), or ( 7 ).

The method for preparing a carbon-based support according to the present invention is also a method for preparing a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer constituent of a fuel cell, the method comprising the steps of:
and a block copolymer in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked with a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90), for supporting metal catalyst particles, is formed on carbon using the sulfonic acid-modified polybenzimidazole.
The method for preparing a carbon-based support according to the present invention is also (10) a method for preparing a carbon-based support for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell, comprising the steps of:
The following general formula [II]:
The present inventors have decided to form a single layer of a support layer on carbon using sulfonic acid-modified polybenzimidazole represented by the formula (I) for supporting metal catalyst particles.

In the present invention, ( 11 ) a carbon-based support for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell is prepared by using a compound represented by the following general formula [I]:
and a block copolymer in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked with a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) , was used as a material for forming a single support layer.
In the present invention, (12) in the preparation of a carbon-based support for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, a carbon-based support represented by the following general formula [II]:
The sulfonic acid-modified polybenzimidazole represented by the following formula was used as a material for forming a single support layer.

The carbon-based support according to the present invention is a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer constituent of a fuel cell, and is represented by the following general formula [I]:
and a block copolymer (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked to a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) is formed on carbon. This eliminates the need to cover the catalyst surface with a proton-conducting polymer, and makes it possible to provide a carbon-based carrier that can increase the amount of oxygen that reaches the catalyst surface, particularly on the oxygen electrode side.
Further, the carbon-based support according to the present invention is a carbon-based support for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, the carbon-based support being represented by the following general formula [II]:
Since a single support layer made of a sulfonic acid-modified polybenzimidazole represented by the formula (I) is formed on carbon, it is not necessary to cover the catalyst surface with a proton-conductive polymer, and it is possible to provide a carbon-based support that can increase the amount of oxygen that reaches the catalyst surface, particularly on the oxygen electrode side.

FIG. 1 is an explanatory diagram showing a method for producing a carbon-based support and analysis results. 3A to 3C are explanatory diagrams showing a procedure for forming a catalyst layer structure and a catalyst-equipped electrode. FIG. 2 is an explanatory diagram showing the characteristics of a fuel cell.

The present invention provides a carbon-based support for supporting catalyst particles that constitute a catalyst layer component of a fuel cell. This carbon-based support does not require the catalyst surface to be covered with a proton-conductive polymer, and can increase the amount of oxygen that reaches the catalyst surface, particularly on the oxygen electrode side.

If the catalyst layer is, for example, a hydrogen electrode catalyst layer formed between the solid polymer membrane and the hydrogen electrode, it will undergo a reaction that decomposes hydrogen, supplied as the negative electrode active material, into protons and electrons. The protons generated here will reach the oxygen electrode through the solid polymer membrane, and the electrons will reach the oxygen electrode via the conductor connecting the hydrogen electrode and oxygen electrode, passing through the load.

In addition, the oxygen electrode catalyst layer formed between the solid polymer membrane and the oxygen electrode reacts with oxygen supplied as the positive electrode active material, protons that reach the oxygen electrode from the hydrogen electrode via the solid polymer membrane, and electrons that reach the oxygen electrode from the hydrogen electrode via the conductor to produce water.

The catalyst layer component is a material that forms the catalyst layer of the fuel cell described above, and includes catalyst particles such as platinum particles and a carbon-based support for supporting the catalyst particles.

The carbon-based support has a carbon material and a support layer on the carbon material for supporting catalyst particles.

The carbon material is not particularly limited as long as it is composed primarily of carbon and has electronic conductivity, but may be, for example, one or a mixture of two or more selected from carbon black, graphene, and carbon nanotubes.

The catalyst particles used in the catalyst layer construct, for example in the hydrogen electrode side catalyst layer, are not particularly limited as long as they can catalyze the reaction that decomposes the negative electrode active material to produce at least protons and electrons. Furthermore, the catalyst particles used in the catalyst layer construct used in the oxygen electrode side catalyst layer are not particularly limited as long as they can catalyze the reaction between protons, electrons, and the positive electrode active material.

The catalyst particles are supported on the carbon support via a single support layer made of a polymer. The support layer in this embodiment is characterized by being made of a polymer whose molecular structure contains a benzene ring and an atom with an unpaired electron, and which is modified with a proton-conducting group.

The polymer may be a polymer of one type of monomer or a polymer of two or more types of monomers, but it is desirable that each monomer contains a benzene ring and an atom having an unpaired electron. An example of such a monomer is a monomer having a benzimidazole skeleton, and an example of a polymer is a polymer having a polybenzimidazole skeleton. The following general formula [I] shows an example of a polymer obtained by polymerizing multiple (two) monomers, in which the constituent ratio of monomer X not modified with a sulfonic acid group to monomer Y modified with a sulfonic acid group is n:m.

The polymer is also modified with proton-conducting groups. This is generally achieved by polymerizing a monomer having a proton-conducting group, but it can also be achieved by modifying the proton-conducting group after the polymerization reaction.

The proton-conducting group is not particularly limited as long as it can guide protons to the solid polymer membrane or catalyst particles by a hopping mechanism, and examples thereof include sulfonic acid groups, sulfonimide groups, phosphonic acid groups, and carboxylic acid groups. The following general formula [II] shows a sulfonic acid-modified polybenzimidazole as an example of a polymer having a sulfonic acid group as a proton-conducting group, and the following general formula [III] shows a sulfonic acid-modified polybenzimidazole as an example of a polymer having a sulfonimide group as a proton-conducting group.

The modification position of the proton-conducting group is not particularly limited, but may be N in the benzimidazole skeleton, as in the polymers represented by the above general formulas [I], [II], and [III]. This structure allows for relatively easy synthesis.

For polymers composed of monomer X not modified with a sulfonic acid group and monomer Y modified with a sulfonic acid group, as represented by the above-mentioned general formula [I], the composition ratio n:m of monomer X to monomer Y can be adjusted appropriately within the range of 1:99 to 99:1.

For example, if the polymer is a random copolymer, the n:m ratio is preferably within the range of 10:90 to 2:98.

The polymer represented by general formula [I] may also be a block copolymer. That is, it can be a block copolymer in which a block Xn, consisting of a predetermined number (n mer) of consecutive monomers X that are not modified with sulfonic acid groups, is linked to a block Ym, consisting of a predetermined number (mmer) of consecutive monomers Y. In this case, the n:m ratio is preferably within the range of 30:70 to 10:90.

With this configuration, the block Xn functions as a unit that supports the metal catalyst through interaction with the metal catalyst, while the block Ym functions as a unit for proton conduction. Compared to random copolymerization, this allows the monomers that exert their respective functions to be assembled at a higher density, making it possible to construct a catalyst layer structure that is more durable and efficient.

By forming a single support layer on a carbon material using a polymer with this configuration, proton conduction is achieved through the proton-conducting groups of the polymer that makes up the support layer. This eliminates the need to cover the catalyst surface with a proton-conducting polymer such as Nafion, and provides a carbon-based support with excellent accessibility of the active material to the catalyst surface.

This also prevents oxygen from reaching the catalyst surface, particularly on the oxygen electrode side, and makes it possible to increase the amount of oxygen supplied compared to catalyst layer structures in which the surface of catalyst particles is covered with a proton-conductive resin, thereby improving the electrical performance of cells and fuel cells.

In addition, the benzene rings of the polymer interact with and stack with the benzene rings on the surface of the carbon material, which is made of carbon, thereby firmly fixing the support layer to the surface of the carbon material.

In addition, the support layer contains atoms with unpaired electrons in its molecular structure, and when the catalyst particles are metal catalysts, the atoms with unpaired electrons interact with the metal atoms of the catalyst particles, thereby providing adhesive properties to the catalyst particles as well.

Furthermore, if catalyst particles are supported on the carbon-based support described above to form a catalyst layer structure, it is possible to form a catalyst-equipped electrode in which the electrode and catalyst layer are integrated by depositing the catalyst layer on a conductive electrode sheet such as carbon paper. This type of catalyst-equipped electrode can provide a catalyst-equipped electrode with excellent accessibility of the active material to the catalyst surface.

Furthermore, if such catalyst-coated electrodes are distributed as components for fuel cells or cells, the catalyst layer will already be formed, so the catalyst layer formation process can be omitted from the fuel cell or cell manufacturing process, improving the manufacturing efficiency of fuel cells and cells.

The above-mentioned catalyst-equipped electrode may be used as either the oxygen electrode or the hydrogen electrode, or both electrodes. However, by using it at least as the oxygen electrode, for example, the amount of oxygen that reaches the catalyst surface can be increased.

Of course, it is also possible to form a cell using such a catalyst-equipped electrode, and to use this cell to construct a fuel cell.

The catalyst layer structure described above may also be deposited on at least the oxygen electrode side surface of a solid polymer membrane to form a catalyst layer, thereby forming a catalyst-coated solid polymer membrane. Such a catalyst-coated solid polymer membrane can also increase the amount of oxygen that reaches the catalyst surface.

The catalyst layer formed on the above-mentioned solid polymer membrane may be formed on either the oxygen electrode side, the hydrogen electrode side, or both sides, but it is preferable to form it at least on the oxygen electrode side.

It is also possible to form a cell using such a catalyst-coated solid polymer membrane, and to use this cell to construct a fuel cell.

The following describes the carbon-based support, catalyst layer structure, catalyst-coated electrode, solid polymer membrane, cell, and fuel cell according to this embodiment, as well as the method for preparing the carbon-based support according to this embodiment and its use as a single-layer support layer-forming material, with reference to specific manufacturing examples and test results.

1. Preparation of carbon-based supports
In the preparation of the carbon-based support in this example, as shown in the upper diagram of Figure 1, conductive carbon black Vulcan (registered trademark) XC72 was used as the carbon material, and sulfonic acid-modified polybenzimidazole (ABPBI-PS) represented by the following general formula [I] with n:m = 2.5:97.5 was used as the polymer for forming the support layer.

A dispersion medium was prepared by thoroughly dissolving sulfonic acid-modified polybenzimidazole (ABPBI-PS: 43.7 mg) as the polymer for forming the support layer in dimethyl sulfoxide (DMSO: 200 ml, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

Next, conductive carbon black (Vulcan® XC72: 200 mg, manufactured by Cabot Corporation) was added to the dispersion medium as a carbon material, and the mixture was subjected to ultrasonic treatment for 10 minutes using a bath-type sonicator (5510, manufactured by Branson Corporation).

The solution was then preliminarily filtered through gauze, and the filtered solution was subjected to suction filtration (membrane filter 0.2 μm PTFE) to obtain a carbon material with the support layer-forming polymer adhered to the membrane filter (process for obtaining carbon with the support layer-forming polymer adhered thereto).

The polymer-adhered carbon for forming the support layer on the membrane filter was then thoroughly washed with DMSO, a good solvent for ABPBI-PS. The black powder after washing was collected on filter paper and dried under reduced pressure at 60°C for 4 to 6 hours to obtain 205 mg of carbon for forming the support layer, i.e., CB/ABPBI-PS as the carbon-based support according to this embodiment (process for producing a carbon-based support).

Next, elemental analysis was performed on the CB/ABPBI-PS obtained in this manner to examine the weight proportion of ABPBI-PS in the carbon-based support.

By comparing the nitrogen content of the conductive carbon black with the nitrogen content of the carbon-based support, the weight percentage of ABPBI-PS in the carbon-based support CB/ABPBI-PS was calculated to be 3.5 wt%, as shown in the lower left of Figure 1.

In addition, thermogravimetric analysis (TGA) was performed to compare the durability of the resulting CB/ABPBI-PS with that of carbon black (CB). As shown by the solid line, the carbon-based support (CB/ABPBI-PS) according to this embodiment exhibited a curve almost identical to that of the raw carbon material, carbon black, shown by the dashed line, and no significant difference was observed in the combustion initiation temperature.

These results confirm that the carbon-based support according to this embodiment has the same durability as the raw material, carbon black.

2. Preparation of catalyst layer structure
Next, catalyst particles were supported on the surface of the carbon-based support, that is, on the support layer formed of sulfonic acid-modified polybenzimidazole provided in CB/ABPBI-PS, to prepare a catalyst layer structure.

Here, the catalyst particles were platinum, and chloroplatinic acid (H ₂ PtCl ₆ ·6H ₂ O) was used as the catalyst raw material component to grow the catalyst particles on the surface of the support layer, thereby forming the catalyst layer structure CB/ABPBI-PS/Pt.

A sample bottle was placed in a 60% aqueous ethylene glycol solution (400 ml) as a dispersion medium and the carbon-based support CB/ABPBI-PS (100 mg), and subjected to ultrasonic treatment.

After sufficient dispersion was confirmed visually, a catalyst raw material solution prepared by dissolving chloroplatinic acid (H ₂ PtCl ₆ ·6H ₂ O, 1.33 mg) as a catalyst raw material component in 60% ethylene glycol aqueous solution (200 ml) was added to the sample bottle and mixed thoroughly.

The mixed solution in the sample bottle was then transferred to a 100 mL three-neck flask and refluxed at 140°C for 6 hours. After cooling to room temperature, the residue was collected by suction filtration (membrane filter: 1 μm PTFE used). The resulting powder was dried under reduced pressure at 60°C for 4 to 6 hours (together with diphosphorus pentoxide as a desiccant) to obtain 100 mg of CB/ABPBI-PS/Pt as a catalyst layer construct (process for producing a catalyst layer construct).

(Confirmation of production of catalyst layer constituent)
Here, the obtained CB/ABPBI-PS/Pt was examined using an electron microscope to determine whether or not platinum, which is a catalyst particle, was supported.

The STEM image of CB/ABPBI-PS/Pt is shown in the lower left of Figure 2. As can be seen from the image, countless platinum catalyst particles with an average particle size of approximately 2.8 nm were observed uniformly supported around the carbon black.

3. Preparation of membrane electrode assembly
Next, a membrane electrode assembly was produced using the prepared CB/ABPBI-PS/Pt. First, 0.37 mL of Milli-Q water and 3.3 mL of 2-propanol were added as dispersion media to 90 mg of CB/ABPBI-PS/Pt as a catalyst layer construct to prepare a catalyst layer construct dispersion liquid in which the catalyst layer construct was dispersed.

Next, as shown in the lower right of Figure 2, this catalyst layer construct dispersion was sprayed onto a Nafion (registered trademark) membrane serving as a solid electrolyte membrane, and dried at 65°C to create a catalyst-coated solid polymer membrane with a catalyst layer of CB/ABPBI-PS/Pt on its surface.

Next, a gas diffusion layer carbon paper (GDL 25BC) with an area of 1 cm ² was placed on the surface of the formed catalyst layer as a gas diffusion layer for supplying an electrode and active material, thereby preparing a membrane electrode composite.

4. Cell Creation and I-V Characteristic Confirmation
Next, a cell was fabricated using the above-mentioned membrane electrode assembly, and the IV characteristics were measured. In this example, the cell was constructed as shown in the schematic diagram in the graph of Figure 3, and measurements were taken while supplying hydrogen to the hydrogen electrode side at 0.1 L per minute and air to the oxygen electrode side at 0.2 L per minute.

As a result, as shown in the graph, unfortunately, the activity of the cell according to this embodiment was slightly lower than that of the cell using CB/Pt, a conventional catalyst layer structure. This is because the cell according to this embodiment is still under development and there is still room for optimization, and we believe that by optimizing it, it will be possible to achieve activity equal to or greater than that of cells using conventional CB/Pt.

Aside from the activity in the low to medium current density range, what is noteworthy about this graph is that the voltage drop curve in the high current density range is gentler than that of a cell using conventional CB/Pt, shown by the dashed line.

Conventional CB/Pt cells have low oxygen diffusivity on the oxygen electrode side, and exhibit a sudden drop in voltage at high current densities because the oxygen supply cannot keep up.

In contrast, the cell according to this embodiment exhibited a gentle voltage drop curve, demonstrating high oxygen diffusivity at the oxygen electrode. In other words, a carbon-based support capable of increasing the amount of oxygen reaching the catalyst surface on the oxygen electrode side, a catalyst-equipped electrode comprising a carbon-based support, a catalyst-equipped solid polymer membrane, a cell, a fuel cell, and a method for preparing a carbon-based support, as well as its use as a support layer constituent material, have been realized.

As mentioned earlier, the activity of the cell according to this embodiment was lower in this test compared to a cell using conventional CB/Pt. However, if future technological improvements and optimizations are made to address this issue and activity in the low to medium current density range is increased, it may be possible to realize cells and fuel cells that maintain high activity in the high current density range, as can be seen by imagining the solid line curve shifting upward to near the dashed line curve.

Furthermore, the carbon-based support according to this embodiment is unique in that it does not use Nafion as a support layer.

Furthermore, in the carbon-based support according to this embodiment, catalyst particles are supported on a support layer that covers the surface of a carbon material, and most of the surface of the catalyst particles is not covered by the support layer, thereby achieving high oxygen diffusibility. Therefore, even if the proton-conducting group of the polymer that constitutes the support layer is changed, this high oxygen diffusibility itself is not affected, and in fact, the proton-conducting group is a compound represented by the following general formula [III]:
Even in the case of a carbon-based support having a support layer formed of a polymer represented by the formula (1), a curve of a gradual voltage drop in the high-density current region, that is, high oxygen diffusivity, can be confirmed.

As described above, the carbon-based support according to this embodiment is a carbon-based support for supporting catalyst particles that constitute a catalyst layer structure for a fuel cell, and has a single support layer formed on carbon, the support layer being made of a polymer that contains a benzene ring and an atom with an unpaired electron in its molecular structure and is modified with a proton-conducting group. This eliminates the need to cover the catalyst surface with a proton-conducting polymer, and makes it possible to provide a carbon-based support that can increase the amount of oxygen that reaches the catalyst surface, particularly on the oxygen electrode side.

Finally, the above-mentioned embodiments are merely examples of the present invention, and the present invention is not limited to the above-mentioned embodiments. Therefore, it goes without saying that various modifications can be made to the design, etc., even in the above-mentioned embodiments, as long as they do not deviate from the technical concept of the present invention.

Claims (12)

A carbon-based support for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell,
The following general formula [I]:
wherein a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked to a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90), is formed on carbon. A carbon-based support for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell,
The following general formula [II]:
1. A carbon-based support comprising a single layer of a sulfonic acid-modified polybenzimidazole represented by the formula (I) formed on carbon. 3. A catalyst layer structure comprising the carbon-based support according to claim 1 or 2, and metal catalyst particles supported on the surface thereof. A catalyst-coated electrode, comprising a catalyst layer formed by depositing the catalyst layer structure according to claim 3 on the surface of an electrode sheet. A cell comprising the catalyst-equipped electrode according to claim 4 as at least an oxygen electrode. 4. A catalyst-coated solid polymer membrane, comprising a catalyst layer formed by depositing the catalyst layer structure according to claim 3 on at least the oxygen electrode side surface of a solid polymer membrane. A cell comprising the catalyst-coated solid polymer membrane according to claim 6 . A fuel cell comprising the cell according to claim 5 or 7 . 1. A method for preparing a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer structure of a fuel cell, comprising:
The following general formula [I]:
and a block copolymer in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked with a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) . 1. A method for preparing a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer structure of a fuel cell, comprising:
The following general formula [II]:
1. A method for preparing a carbon-based support, comprising forming a monolayer support layer on carbon using a sulfonic acid-modified polybenzimidazole represented by the formula (I) for supporting metal catalyst particles. In preparing a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer structure of a fuel cell,
The following general formula [I]:
and a block copolymer in which a block Xn in which a predetermined number (n mer) of consecutive monomers X not modified with sulfonic acid groups is linked with a block Ym in which a predetermined number (mmer) of consecutive monomers Y are linked (where n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90) , as a material for constituting a single-layer support layer. In preparing a carbon-based support for supporting metal catalyst particles that constitute a catalyst layer structure of a fuel cell,
The following general formula [II]:
Use of a sulfonic acid-modified polybenzimidazole represented by the formula (I) as a material for forming a single-layer support layer.