Carbon-based carrier and method for preparing carbon-based carrier

Abstract

To provide a carbon-based carrier capable of increasing the amount of oxygen reaching the catalyst surface, particularly on the oxygen electrode side, without having to cover the catalyst surface with a polymer having proton conductivity.SOLUTION: In a carbon-based carrier for supporting catalyst particles constituting a catalyst layer structure of a fuel cell, a single carrying layer made of a polymer containing a benzene ring and an atom having an unpaired electron in a molecular structure and modified with a proton conductive group is formed on carbon.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a carbon-based carrier for supporting catalyst particles constituting a catalyst layer structure of a fuel cell and a method for preparing the carbon-based carrier.

Background Art

[0002] A fuel cell supplies and reacts a negative electrode active material such as hydrogen and a positive electrode active material such as oxygen in the air, thereby generating a potential difference between an electrode disposed on the supply side of the negative electrode active material (hereinafter also referred to as a hydrogen electrode) and an electrode disposed on the supply side of the positive electrode active material (hereinafter also referred to as an oxygen electrode), and extracting electric power. By continuously replenishing these active materials, it is possible to continuously extract electric power without being limited by the electric capacity. In addition, the by-products associated with power generation are often mainly water, and thus it has attracted wide attention from the viewpoints of economy and environmental load.

[0003] A polymer electrolyte fuel cell, which is classified as one of such fuel cells, generally forms catalyst layers on both sides of a polymer electrolyte membrane made of a proton-conductive polymer such as Nafion (registered trademark), and sandwiches the polymer electrolyte membrane with the catalyst layers formed thereon between electrodes such as carbon paper in a sandwich shape from both sides to form a cell, and this cell is configured by connecting a single cell or a plurality of cells in series or in parallel (stack).

[0004] Among the respective components of these fuel cells, the catalyst layer is a place for generating electrons and protons from the negative electrode active material and reacting electrons and protons with the positive electrode active material, and is a site that plays an important role in the power generation mechanism of the fuel cell.

[0005] As an example of the configuration of the catalyst layer, for example, a so-called platinum carbon black in which fine particles of platinum are supported on activated carbon black is used as a catalyst layer structure, and it is known to be attached to both sides of an electrode or a polymer electrolyte membrane together with Nafion (registered trademark; hereinafter simply referred to as "Nafion") having proton conductivity.

[0006] However, in the fuel cell using the above conventional platinum carbon black as a catalyst layer constituent, for example, in the catalyst layer on the oxygen electrode side, there has been a problem that a proton-conductive polymer such as Nafion is likely to be lost due to moisture generated by electrification.

[0007] 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 through the proton-conductive polymer in the catalyst layer on the oxygen electrode side. However, due to the acidic functional groups of the proton-conductive polymer required for proton conduction, the hydration property of the proton-conductive polymer itself is high, and as the fuel cell operates, the proton-conductive polymer in the catalyst layer on the oxygen electrode side is lost by the water generated by the reaction, the catalyst layer deteriorates, and there is a problem that the electromotive force decreases.

[0008] Therefore, in the past, the present inventor proposed a technique of supporting catalyst particles via a support layer composed of two upper and lower layers on carbon, forming the upper layer of the support layer with a polymer having proton conductivity as a proton conduction layer for conducting protons generated by the catalyst particles or protons to be supplied to the catalyst particles, while forming the lower layer of the support layer with a polymer having an affinity for both the proton conduction layer and carbon and containing a benzene ring and a basic structure in the molecular structure as an adhesive layer for adhering the proton conduction layer and carbon (see, for example, Patent Document 1).

[0009] According to this, the proton conduction layer is arranged with respect to carbon via the adhesive layer, and it is possible to prevent as much as possible the proton conduction layer from being lost by water, and to suppress the deterioration of the catalyst layer and the decrease in the electromotive force.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] Thus, although the above-described conventional technology provides an excellent catalyst layer structure, there is still room for improvement in the power generation performance.

[0012] That is, in the above-described conventional technology, when the catalyst surface is covered with a polymer having proton conductivity, there is a problem that the amount of oxygen reaching the catalyst surface is suppressed, particularly on the oxygen electrode side, and sufficient power generation performance cannot be exhibited.

[0013] The present invention has been made in view of such circumstances, and provides a carbon-based carrier that does not require covering the catalyst surface with a polymer having proton conductivity and can increase the amount of oxygen reaching the catalyst surface, particularly on the oxygen electrode side.

[0014] The present invention also provides a catalyst layer structure including the above-described carbon-based carrier, a catalyst electrode, a catalyst solid polymer membrane, a cell, a fuel cell, a method for preparing the carbon-based carrier, and use as a supporting layer constituent material.

Means for Solving the Problems

[0015] In order to solve the above-described conventional problems, in the carbon-based carrier according to the present invention, (1) a carbon-based carrier for supporting catalyst particles constituting a catalyst layer structure of a fuel cell, Metal wherein a single-layer supporting layer consisting of The following general formula [I]:

Chemical formula

Chemical formula

[0017] Also, in the catalyst layer structure according to the present invention, ( 3 )( ) or (2) to the carbon-based carrier described in (1 Metal is made to support catalyst particles on its surface.

[0018] Also, in the electrode with a catalyst according to the present invention, ( 4 )( 3 the catalyst layer structure described in (

[0019] is deposited on the surface of the electrode sheet to form a catalyst layer. 5 )( 4 Also, in the cell according to the present invention, (

[0020] is provided with the electrode with a catalyst described in ( 6 )( 3 at least as the oxygen electrode side electrode.

[0021] Also, in the cell according to the present invention, ( 7 )( 6 is provided with the solid polymer membrane with a catalyst described in (

[0022] Also, in the fuel cell according to the present invention, ( 8 )( 5 ) or ( 7 ) is provided with the cell described in (

[0023] Also, in the method for preparing a carbon-based carrier according to the present invention, ( 9 ) a method for preparing a carbon-based carrier for supporting catalyst particles that constitute a catalyst layer structure of a fuel cell, Metal is such that a single-layer support layer for supporting catalyst particles is formed on carbon. The following general formula [I]:

Chemical formula

[0024] Also, in the present invention, ( 11 ) in the preparation of a carbon-based carrier for supporting catalyst particles that constitute the catalyst layer structure of a fuel cell, Metal The following general formula [I]: [Chemical formula] A block copolymer in which a block Xn in which a predetermined number (nmer) of monomers X not modified with a sulfonic acid group are continuous and a block Ym in which a predetermined number (mmer) of monomers Y are continuous are linked (however, n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90). The sulfonic acid-modified polybenzimidazole is used as a single-layer support layer constituent material. Further, in the present invention, (12) in the preparation of a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, the following general formula [II]: [Chemical formula] The sulfonic acid-modified polybenzimidazole represented by the formula is used as a single-layer support layer constituent material. [Advantages of the Invention]

[0025] According to the carbon-based carrier of the present invention, a carbon-based carrier for supporting catalyst particles that constitute the catalyst layer structure of a fuel cell, Metal The following general formula [I]: [Chemical formula] A block copolymer in which a block Xn in which a predetermined number (nmer) of monomers X represented by the formula and not modified with a sulfonic acid group are continuous and a block Ym in which a predetermined number (mmer) of monomers Y are continuous are linked (however, n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90). Sulfonic acid-modified polybenzimidazole Since a single-layer support layer composed of the above is formed on the carbon, it is not necessary to cover the catalyst surface with a polymer having proton conductivity, and it is possible to provide a carbon-based carrier capable of increasing the amount of oxygen reaching the catalyst surface, particularly on the oxygen electrode side. Further, according to the carbon-based carrier of the present invention, a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer constituent of a fuel cell, represented by the following general formula [II]: [Chemical formula] Since a single-layer support layer made of the sulfonic acid-modified polybenzimidazole represented by the formula is formed on the carbon, it is not necessary to cover the catalyst surface with a polymer having proton conductivity, and in particular, it is possible to provide a carbon-based carrier capable of increasing the amount of oxygen reaching the catalyst surface on the oxygen electrode side. [Brief Description of the Drawings]

[0026]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0027] The present invention provides a carbon-based carrier for supporting catalyst particles that constitute a catalyst layer structure of a fuel cell, which does not require a polymer having proton conductivity to cover the catalyst surface, and can particularly increase the amount of oxygen reaching the catalyst surface on the oxygen electrode side.

[0028] For example, if the catalyst layer is a hydrogen electrode side catalyst layer formed between a solid polymer membrane and a hydrogen electrode side electrode, it performs a reaction of decomposing hydrogen supplied as a negative electrode active material into protons and electrons. The protons generated here reach the oxygen electrode side through the solid polymer membrane, and the electrons reach the oxygen electrode side through a load via a conducting wire connecting the hydrogen electrode side electrode and the oxygen electrode side electrode.

[0029] Also, the oxygen electrode side catalyst layer formed between the solid polymer membrane and the oxygen electrode side electrode performs a reaction of generating water with oxygen supplied as a positive electrode active material, protons reaching the oxygen electrode side from the hydrogen electrode side through the solid polymer membrane, and electrons reaching the oxygen electrode side from the hydrogen electrode side through the conducting wire.

[0030] The catalyst layer structure is a substance that becomes a material constituting the catalyst layer of the fuel cell as described above, and includes catalyst particles such as platinum particles and a carbon-based carrier for supporting the catalyst particles.

[0031] The carbon-based carrier has a carbon material and a support layer for supporting catalyst particles on the same carbon material.

[0032] The carbon material is not particularly limited as long as it is composed mainly of carbon and has electronic conductivity. For example, it may be any one selected from carbon black, graphene, and carbon nanotubes, or a mixture of two or more thereof.

[0033] The catalyst particles used in the catalyst layer structure are not particularly limited as long as they can catalyze a reaction that decomposes the negative electrode active material to generate at least protons and electrons, for example, in the catalyst layer structure used in the hydrogen electrode side catalyst layer. Further, the catalyst particles used in the catalyst layer structure used in the oxygen electrode side catalyst layer are not particularly limited as long as they can catalyze the reaction of protons, electrons, and the anode active material.

[0034] The catalyst particles are supported on the carbon carrier via a single-layer support layer made of a polymer. Here, the characteristics of the support layer according to the present embodiment include that it is made of a polymer containing a benzene ring and an atom having an unpaired electron in the molecular structure and modified with a proton conduction group.

[0035] The polymer may be obtained by polymerizing one type of monomer, or may be obtained by polymerizing two or more types of monomers. However, it is desirable that each monomer contains a benzene ring and an atom having an unpaired electron. As an example of such a monomer, for example, a monomer having a benzimidazole skeleton can be mentioned. As an example of the polymer, a polymer having a polybenzimidazole skeleton can be mentioned. The following general formula [I] shows a polymer in which the composition ratio of the unmodified monomer X and the modified monomer Y is n:m as an example of polymerizing a plurality (two types) of monomers.

Chemical formula

[0036] Further, the polymer is modified with a proton conduction group. This is generally obtained by polymerizing a monomer having a proton conduction group, but it may also be obtained by modifying the proton conduction group after the polymerization reaction.

[0037] The proton-conducting group is not particularly limited as long as it can conduct protons to a solid polymer membrane or catalyst particles by a hopping mechanism. Examples thereof include a sulfonic acid group, a sulfonimide group, a phosphonic acid group, and a carboxylic acid group. 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.

Chemical formula

Chemical formula

[0038] In addition, the modification position of the proton-conducting group is not particularly limited, but it may be N of the benzimidazole skeleton as in the polymers represented by the above general formulas [I], [II], and [III]. By adopting such a configuration, synthesis can be carried out relatively easily.

[0039] Regarding the polymer composed of the unmodified monomer X and the modified monomer Y represented by the above-mentioned general formula [I], the composition ratio n:m of the monomer X and the monomer Y can be appropriately adjusted within the range of 1:99 to 99:1.

[0040] For example, when the polymer is a random copolymer, n:m is preferably in the range of 10:90 to 2:98.

[0041] In addition, the polymer represented by the general formula [I] may be a block copolymer. That is, it can also be a block copolymer in which a block Xn in which a predetermined number (nmer) of unmodified monomers X are continuous and a block Ym in which a predetermined number (mmer) of monomers Y are continuous are linked. In this case, n:m is preferably in the range of 30:70 to 10:90.

[0042] With such a configuration, block Xn functions as a unit for supporting a metal catalyst through interaction with the metal catalyst, while block Ym functions as a unit for proton conduction, and monomers for exerting respective functions can be assembled at a high density as compared with the case of random copolymerization. Therefore, it is possible to realize a catalyst layer structure that is more excellent in durability and also has high efficiency.

[0043] Then, by forming a single-layer support layer on a carbon material with a polymer having such a configuration, proton conduction is realized by the proton conduction groups of the polymer constituting the support layer. Therefore, it is not necessary to cover the catalyst surface with a polymer having proton conductivity such as Nafion, and a carbon-based carrier with excellent accessibility of the active material to the catalyst surface can be provided.

[0044] Also, this does not inhibit oxygen reaching the catalyst surface, particularly on the oxygen electrode side, and it is possible to increase the oxygen supply amount compared to a catalyst layer structure in which the surface of catalyst particles is covered with a proton-conductive resin, thereby improving the electrical performance of the cell or fuel cell.

[0045] In addition, the benzene ring of the polymer interacts with and stacks on the benzene ring on the surface of the carbon material composed of carbon, so that the support layer is firmly fixed on the surface of the carbon material.

[0046] Moreover, the support layer contains an atom having an unpaired electron in its molecular structure. When the catalyst particles are made of a metal catalyst, the atom having an unpaired electron interacts with the metal atom of the catalyst particles, and can also exhibit an adhesive function with respect to the catalyst particles.

[0047] In addition, if the carbon-based carrier described above is used to construct a catalyst layer structure by supporting catalyst particles on the carbon-based carrier, a catalyst-coated electrode in which the electrode and the catalyst layer are integrated can be formed by depositing the structure on a conductive electrode sheet such as carbon paper. According to such a catalyst-coated electrode, a catalyst-coated electrode with excellent accessibility of the active material to the catalyst surface can be provided.

[0048] Moreover, if such a catalyst-coated electrode is used as a component for forming a fuel cell or a cell and distributed, since the catalyst layer is pre-formed, the process of forming the catalyst layer can be omitted in the process of forming the fuel cell or the cell, and the manufacturing efficiency of the fuel cell or the cell can be improved.

[0049] It should be noted that the above-mentioned catalyst-coated electrode can be used as any of the oxygen electrode, hydrogen electrode, and both electrodes. For example, by using it as at least the electrode on the oxygen electrode side, the amount of oxygen reaching the catalyst surface can be increased.

[0050] In addition, it is of course possible to form a cell with such a catalyst-coated electrode or to configure a fuel cell using this cell.

[0051] Furthermore, the above-mentioned catalyst layer structure may be deposited on at least the oxygen electrode side surface of the solid polymer membrane to form a catalyst layer, thereby constituting a catalyst-coated solid polymer membrane. Also with such a catalyst-coated solid polymer membrane, the amount of oxygen reaching the catalyst surface can be increased.

[0052] It should be noted that the catalyst layer formed on the above-mentioned solid polymer membrane may be formed on either the oxygen electrode side surface, the hydrogen electrode side surface, or both surfaces. For example, it is preferably formed on at least the oxygen electrode side surface.

[0053] In addition, it is of course possible to form a cell with such a catalyst-coated solid polymer membrane or to configure a fuel cell using this cell.

[0054] Hereinafter, regarding the carbon-based carrier, catalyst layer construct, electrode with catalyst, solid polymer membrane, cell, fuel cell according to this embodiment, and further, regarding the preparation method of the carbon-based carrier according to this embodiment and its use as a single-layer support layer constituent material, a description will be given with reference to specific production examples and test results.

[0055] [1. Preparation of Carbon-Based Carrier] In the preparation of the carbon-based carrier in this example, as shown in the upper figure of Fig. 1, Vulcan (registered trademark) XC72, which is conductive carbon black 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 as the polymer for forming the support layer were used. [Chemical formula]

[0056] Sulfonic acid-modified polybenzimidazole (ABPBI-PS: 43.7 mg) as the polymer for forming the support layer was sufficiently dissolved in dimethyl sulfoxide (DMSO: 200 ml, manufactured by Fujifilm Wako Pure Chemical Corporation) to prepare a dispersion medium.

[0057] Next, conductive carbon black (Vulcan (registered trademark) XC72: 200 mg, manufactured by Cabot Corporation) as the carbon material was added to this dispersion medium, and ultrasonic treatment was performed for 10 minutes using a bath-type sonicator (5510, manufactured by BRANSON).

[0058] Then, this solution was 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 polymer for forming the support layer attached on the membrane filter (step of obtaining carbon with the polymer for forming the support layer attached).

[0059] Then, the carbon supporting the polymer for forming the supporting layer on the membrane filter, which was carbon with ABPBI-PS attached, was thoroughly washed with DMSO, which is a good solvent for ABPBI-PS. The black powder after washing was collected on filter paper and dried at 60 °C under reduced pressure for 4 to 6 hours, thereby obtaining 205 mg of carbon for forming the supporting layer, that is, CB / ABPBI-PS as the carbon-based carrier according to this embodiment (the step of generating the carbon-based carrier).

[0060] Next, regarding the CB / ABPBI-PS thus obtained, elemental analysis was performed to examine the weight ratio occupied by ABPBI-PS in the carbon-based carrier.

[0061] As a result of comparison and calculation of the nitrogen content in the conductive carbon black and the nitrogen content in the carbon-based carrier, as shown in the lower left of FIG. 1, the weight ratio occupied by ABPBI-PS in CB / ABPBI-PS, which is the carbon-based carrier, was 3.5 wt%.

[0062] In addition, in order to compare the durability of the obtained CB / ABPBI-PS with that of carbon black (CB), thermogravimetric analysis (TGA) was performed. As shown by the solid line, the carbon-based carrier (CB / ABPBI-PS) according to this embodiment exhibited almost the same curve as the carbon black shown by the broken line, which is the raw carbon material, and no significant difference was observed in the combustion start temperature.

[0063] From this result, it was confirmed that the carbon-based carrier according to this embodiment has equivalent durability compared to the carbon black as the raw material.

[0064] 〔2. Preparation of the Catalyst Layer Assembly〕 Next, the catalyst layer assembly was prepared by supporting catalyst particles on the surface of the carbon-based carrier, that is, on the supporting layer formed of sulfonic acid-modified polybenzimidazole provided in CB / ABPBI-PS.

[0065] Here, the catalyst particles are platinum, and chloroplatinic acid (H2PtCl6·6H2O) is used as the catalyst raw material component. The catalyst particles are grown on the surface of the support layer to form the catalyst layer structure CB / ABPBI-PS / Pt.

[0066] In a sample bottle, 60% ethylene glycol aqueous solution (400 ml) as a dispersion medium and carbon-based support CB / ABPBI-PS (100 mg) were contained and subjected to ultrasonic treatment.

[0067] After sufficient dispersion was visually confirmed, a catalyst raw material solution prepared by dissolving chloroplatinic acid (H2PtCl6·6H2O, 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 well.

[0068] Thereafter, the mixed solution in the sample bottle was transferred to a 100 mL three-necked flask, refluxed at 140 °C for 6 hours, cooled to room temperature, and then the filtrate was collected by suction filtration (using a membrane filter: 1 μm PTFE). The obtained powder was dried at 60 °C under reduced pressure for 4 - 6 hours (together with phosphorus pentoxide as a desiccant) to obtain 100 mg of CB / ABPBI-PS / Pt as a catalyst layer structure (the step of generating the catalyst layer structure).

[0069] (Confirmation of the generation of the catalyst layer structure) Here, regarding the obtained CB / ABPBI-PS / Pt, it was confirmed by an electron microscope whether platinum, which is the catalyst particle, was supported or not.

[0070] The STEM image of CB / ABPBI-PS / Pt is shown at the lower left of Figure 2. As can be seen from the figure, it was observed that catalyst particles composed of platinum with an average particle size of about 2.8 nm were uniformly and innumerably supported around the carbon black.

[0071] [3. Preparation of the 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.

[0072] Next, as shown in the lower right of FIG. 2, this catalyst layer construct dispersion liquid was sprayed onto a Nafion (registered trademark) membrane as a solid electrolyte membrane, and dried at 65°C to prepare a catalyst-loaded solid polymer membrane having a catalyst layer of CB / ABPBI-PS / Pt on the surface.

[0073] Next, a gas diffusion layer with an area of 1 cm was formed on the surface of the formed catalyst layer as an electrode and active material supply layer. 2 A gas diffusion layer carbon paper (GDL 25BC) was placed on the electrode to form a membrane electrode assembly.

[0074] [4. Creating a cell and checking the IV characteristics] 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 at 0.1 L per minute and air to the oxygen electrode at 0.2 L per minute.

[0075] As a result, as shown in the graph, the cell according to this embodiment unfortunately had slightly lower activity compared to the cell using CB / Pt, which is 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 it is believed that by performing optimization it is possible to achieve activity equal to or higher than that of a cell using conventional CB / Pt.

[0076] Furthermore, aside from the activity in the low to medium current density range, what is noteworthy in 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.

[0077] Conventional cells using CB / Pt have low oxygen diffusivity on the oxygen electrode side, and exhibit a sharp voltage drop because the supply of oxygen cannot keep up in the high current density region.

[0078] In contrast, the cell according to this embodiment has a gentle voltage drop curve, and high oxygen diffusivity was observed at the oxygen electrode. That is, a carbon-based carrier, a catalyst layer structure including a carbon-based carrier, a catalyst-coated electrode, a catalyst-coated solid polymer membrane, a cell, a fuel cell, a method for preparing a carbon-based carrier, and use as a support layer constituent material that can increase the amount of oxygen reaching the catalyst surface on the oxygen electrode side have been realized.

[0079] As previously mentioned, the cell according to this embodiment had lower activity in this test compared to the conventional cell using CB / Pt. However, if technological improvements and optimizations are made in the future and the activity in the low current to medium current density region increases, it is suggested that it is possible to realize a cell or fuel cell that maintains high activity in the high current density region, as can be understood by imagining shifting the solid line curve upward to near the dashed line curve.

[0080] Also, it can be said that the carbon-based carrier according to this embodiment is characteristic in that it does not use Nafion as the support layer.

[0081] In addition, the carbon-based carrier according to this embodiment has catalyst particles supported on a support layer that covers the surface of the carbon material, and most of the surface of the catalyst particles is not covered by the support layer, thereby realizing high oxygen diffusivity. Therefore, even when the proton-conducting group of the polymer constituting the support layer is changed, it does not affect this high oxygen diffusivity itself. In fact, in the case of a carbon-based carrier formed with a support layer using a polymer represented by the following general formula [III]:

Chemical formula

[0082] As described above, according to the carbon-based carrier of the present embodiment, it is a carbon-based carrier for supporting catalyst particles constituting the catalyst layer structure of a fuel cell, and a single-layer support layer made of a polymer containing a benzene ring and an atom having an unpaired electron in its molecular structure and modified with a proton-conducting group is formed on the carbon. Therefore, it is not necessary to cover the catalyst surface with a polymer having proton conductivity, and it is possible to provide a carbon-based carrier capable of increasing the amount of oxygen reaching the catalyst surface, particularly on the oxygen electrode side.

[0083] Finally, the description of each of the above-described embodiments is an example of the present invention, and the present invention is not limited to the above-described embodiments. Therefore, it goes without saying that various modifications can be made according to the design and the like as long as they are within the scope not departing from the technical idea of the present invention even if they are outside the above-described embodiments.

Claims

1. A carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell, represented by the following general formula [I]: 【Chemical 1】 A block copolymer in which a block Xn in which a predetermined number (nmer) of monomers X not modified with a sulfonic acid group are continuous and a block Ym in which a predetermined number (mmer) of monomers Y are continuous are linked (however, n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90). A carbon-based carrier characterized in that a single-layer support layer made of a sulfonic acid-modified polybenzimidazole is formed on the carbon.

2. A carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell, represented by the following general formula [II]: 【Chemical 2】 A carbon-based carrier characterized in that a single-layer support layer made of a sulfonic acid-modified polybenzimidazole is formed on the carbon.

3. A catalyst layer structure obtained by supporting metal catalyst particles on the surface of the carbon-based carrier according to Claim 1 or Claim 2.

4. A catalyst-coated electrode characterized in that the catalyst layer structure according to Claim 3 is deposited on the surface of an electrode sheet to form a catalyst layer.

5. A cell characterized by comprising the catalyst-coated electrode according to Claim 4 as at least an oxygen electrode side electrode.

6. A catalyst-coated solid polymer membrane characterized in that the catalyst layer structure according to Claim 3 is deposited on at least the oxygen electrode side surface of a solid polymer membrane to form a catalyst layer.

7. A cell characterized by comprising the catalyst-coated solid polymer membrane according to Claim 6.

8. A fuel cell comprising the cell according to Claim 5 or Claim 7.

9. A method for preparing a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell, represented by the following general formula [I]: 【Chemical Formula 3】 A method for preparing a carbon-based carrier, characterized in that a single-layer support layer for supporting metal catalyst particles is formed on the carbon with a sulfonic acid-modified polybenzimidazole which is a block copolymer in which a block Xn in which a predetermined number (nmer) of monomers X not modified with a sulfonic acid group are continuous and a block Ym in which a predetermined number (mmer) of monomers Y are continuous are linked (however, n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90).

10. A method for preparing a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer structure of a fuel cell, represented by the following general formula [II]: 【Chemical Formula 4】 A method for preparing a carbon-based carrier, characterized in that a single-layer support layer for supporting metal catalyst particles is formed on carbon with a sulfonic acid-modified polybenzimidazole represented by

11. In the preparation of a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer assembly of a fuel cell, The following general formula [I]: 【Chemical Formula 5】 A block copolymer in which a block Xn in which a predetermined number (nmer) of monomers X represented by and not modified with a sulfonic acid group are consecutive and a block Ym in which a predetermined number (mmer) of monomers Y are consecutive are linked (however, n is 10 to 30, m is 70 to 90, and n:m is 30:70 to 10:90). Use of the sulfonic acid-modified polybenzimidazole as a single-layer support layer constituent material.

12. In the preparation of a carbon-based carrier for supporting metal catalyst particles constituting a catalyst layer assembly of a fuel cell, The following general formula [II]: 【Chemical Formula 6】 Use of the sulfonic acid-modified polybenzimidazole represented by as a single-layer support layer constituent material.

Images