JP2018198182A - Electrode catalyst layer for fuel cell and method of producing the same - Google Patents

Abstract

To suppress a decrease in proton conductivity of an electrode catalyst layer for a fuel cell and furthermore improve durability of a metal catalyst particle included in the electrode catalyst layer.SOLUTION: An electrode catalyst layer 900 for a fuel cell is constituted of: an electrode catalyst 500 in which a metal catalyst particle 400 is carried by a carrier particle 300; and an electrolyte resin 800. Surfaces of the metal catalyst particle 400 and the carrier particle 300 are coated with the electrolyte resin 800. Concentration of an ion exchange group of an electrolyte resin 600 in a region in proximity to a surface of the metal catalyst particle 400 is lower than concentration of an ion exchange group of an electrolyte resin 700 in a region with which the surface of the carrier particle 300 is coated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell for use in a portable power source, a power source for portable devices, a power source for electric vehicles, a domestic cogeneration system, and the like.

  A conventional general fuel cell includes an electrolyte membrane-electrode assembly in which an anode and a cathode are formed on both sides of an electrolyte membrane, supplies a fuel gas containing at least hydrogen to the anode, and an oxidant gas containing at least oxygen as a cathode. To generate electricity.

  In addition, the anode and the cathode are provided with an electrocatalyst in which metal catalyst particles are supported in a highly dispersed manner on the surface of a chemically stable carrier particle in order to promote an electrochemical reaction between a fuel gas and an oxidant gas, and proton conductivity. The electrode catalyst layer is made of an electrolyte resin.

  Usually, a strongly acidic sulfonic acid group is used as the ion exchange group of the electrolyte resin. The electrolyte resin having a strongly acidic sulfonic acid group is coated in a region close to the metal catalyst particles constituting the electrode catalyst, whereby ionization of the metal catalyst particles is promoted, and the electrode catalyst of the electrode catalyst layer for the fuel cell The activity of is reduced.

  In order to solve the problem, an electrode in which the surface of metal catalyst particles and carrier particles is coated with a fluorine compound not containing an ion exchange group by mixing a dispersion of the fluorine compound not containing an ion exchange group and an electrode catalyst. It has been proposed to use a catalyst for a fuel cell (see, for example, Patent Document 1).

  In the fuel cell electrode catalyst layer composed of the electrode catalyst and the electrolyte resin, since the strongly acidic ion exchange groups of the electrolyte resin can be prevented from coming into contact with the metal catalyst particles of the electrode catalyst, the ionization of the metal catalyst particles is prevented. As a result, the durability of the metal catalyst particles is improved.

International Publication No. 2014/126077

  However, in the conventional structure, not only the surface of the metal catalyst particles but also the surface of the carrier particles are coated with a fluorine compound that does not contain an ion exchange group. Therefore, a fuel composed of this electrode catalyst and an electrolyte resin is used. In the battery electrode catalyst layer, the concentration of the ion exchange groups of the electrolyte resin coated with the carrier particles is lowered, so that the acidity is lowered and the proton diffusion path is reduced.

  In addition, since water is coordinated on the outer peripheral portion of the ion exchange group, the water content of the electrolyte resin coated on the surface of the carrier particles is reduced as the concentration of the ion exchange group is decreased. As a result, there has been a problem that the proton conductivity of the electrolyte resin on the surface of the carrier particles is lowered.

  Furthermore, in the conventional manufacturing method in which the dispersion of the fluorine compound and the electrode catalyst are mixed, a region in which the surface of the metal catalyst particle is thickly coated with the fluorine compound layer not containing the ion exchange group is formed. There was a problem that the proton conductivity in the vicinity of the catalyst particles also decreased.

Then, in view of the conventional subject, this invention aims at improving the durability of a metal catalyst particle, suppressing the fall of the proton conductivity of the electrode catalyst layer for fuel cells.

  In order to solve the above-mentioned conventional problems, a fuel cell electrode catalyst layer according to the present invention is a fuel cell electrode catalyst layer comprising an electrode catalyst in which metal catalyst particles are supported on carrier particles and an electrolyte resin. The surfaces of the metal catalyst particles and the carrier particles are coated with an electrolyte resin, and the concentration of the ion exchange group of the electrolyte resin in the region close to the surface of the metal catalyst particles is the region of the electrolyte that covers the surface of the carrier particles. The electrode catalyst layer for a fuel cell is characterized by being lower than the concentration of ion exchange groups in the resin.

  This configuration reduces only the ion exchange group concentration of the electrolyte resin coated in the vicinity of the surface of the metal catalyst particles without reducing the ion exchange group concentration and moisture content of the electrolyte resin coated on the surface of the carrier particles. Can be made. Moreover, it can suppress that the ion exchange group of electrolyte resin contacts a metal catalyst particle.

  As a result, the durability of the metal catalyst particles can be improved while suppressing a decrease in proton conductivity of the fuel cell electrode catalyst layer. Further, by constituting a fuel cell using the electrode catalyst layer for a fuel cell of the present invention, a fuel cell having low proton conduction resistance and reaction resistance and high durability of the electrode catalyst can be realized.

  The electrode catalyst layer for a fuel cell according to the present invention has an ion of the electrolyte resin coated in the vicinity of the surface of the metal catalyst particle without reducing the concentration and moisture content of the ion exchange group of the electrolyte resin coated on the surface of the carrier particle. Only the concentration of exchange groups can be reduced. Moreover, it can suppress that the ion exchange group of electrolyte resin contacts a metal catalyst particle, and can reduce ionization of a metal catalyst particle.

  As a result, the durability of the metal catalyst particles can be improved while suppressing a decrease in proton conductivity of the fuel cell electrode catalyst layer. Further, by constituting a fuel cell using the electrode catalyst layer for a fuel cell of the present invention, a fuel cell having low proton conduction resistance and reaction resistance and high durability of the electrode catalyst can be realized.

Sectional drawing which shows schematic structure of the electrode catalyst layer for fuel cells concerning Embodiment 1 of this invention. The flowchart which shows the manufacturing process of the electrode catalyst layer for fuel cells concerning Embodiment 1 of this invention. Sectional drawing which shows schematic structure of the fuel cell concerning Embodiment 1 of this invention. Sectional drawing which shows schematic structure of the electrode catalyst layer for fuel cells concerning Embodiment 2 of this invention. A flowchart which shows the manufacturing process of the electrode catalyst layer for fuel cells concerning Embodiment 2 of this invention. Sectional drawing which shows schematic structure of the fuel cell concerning Embodiment 2 of this invention. Sectional drawing which shows schematic structure of the electrode catalyst layer for fuel cells concerning Embodiment 3 of this invention. A flowchart which shows the manufacturing process of the electrode catalyst layer for fuel cells concerning Embodiment 3 of this invention. Sectional drawing which shows schematic structure of the electrochemical cell used for the manufacturing process of the electrode catalyst layer for fuel cells concerning Embodiment 3 of this invention. Sectional drawing which shows schematic structure of the fuel cell concerning Embodiment 3 of this invention.

  A first invention is an electrode catalyst layer for a fuel cell comprising an electrode catalyst in which metal catalyst particles are supported on carrier particles and an electrolyte resin, and the surfaces of the metal catalyst particles and the carrier particles are made of an electrolyte resin. The concentration of the ion exchange group of the electrolyte resin in the region that is coated and close to the surface of the metal catalyst particle is lower than the concentration of the ion exchange group of the electrolyte resin in the region that covers the surface of the carrier particle. .

  This reduces only the ion exchange group concentration of the electrolyte resin coated in the vicinity of the surface of the metal catalyst particles without reducing the ion exchange group concentration and moisture content of the electrolyte resin coated on the surface of the carrier particles. It becomes possible. Moreover, it can suppress that the ion exchange group of electrolyte resin contacts a metal catalyst particle, and can reduce ionization of a metal catalyst particle.

  As a result, it is possible to improve the durability of the metal catalyst particles while suppressing a decrease in proton conductivity of the fuel cell electrode catalyst layer.

  In particular, the second invention is characterized in that, in the first invention, the electrolyte resin in a region close to the surface of the metal catalyst particles does not have an ion exchange group.

  Thereby, it can prevent that the ion exchange group of electrolyte resin contacts a metal catalyst particle, and can improve the durability of a metal catalyst particle more. Moreover, adsorption of the ion exchange group of the electrolyte resin on the surface of the metal catalyst particles can be eliminated, and the effective reaction sites of the metal catalyst particles can be increased.

  The third invention is characterized in that, in the first or second invention, the electrolyte resin in a region close to the surface of the metal catalyst particles has water repellency.

  Thereby, by reducing the water content of the electrolyte resin in the region close to the surface of the metal catalyst particles, it is possible to suppress the oxidation of the metal catalyst particles by water and further improve the durability of the metal catalyst particles. .

  A fourth invention is characterized in that, in any one of the first to third inventions, the electrolyte resin in a region covering the surface of the carrier particles has hydrophilicity.

  As a result, the moisture content on the surface of the carrier particles can be increased and the proton diffusion path can be increased, so that it is possible to further suppress the decrease in proton conductivity of the electrode catalyst layer for fuel cells.

  5th invention removes an ion exchange group from the electrolyte resin of the area | region close to the surface of a metal catalyst particle, after coat | covering the electrolyte resin which has an ion exchange group to the electrode catalyst with which the metal catalyst particle was carry | supported by the support particle This is a method for producing a fuel cell electrode catalyst layer.

  By this method, the ion exchange group is removed only from the electrolyte resin in the region close to the surface of the metal catalyst particles, and the thickness of the electrolyte resin having a low proton conductivity on the surface of the metal catalyst particles is reduced. It is possible to further suppress a decrease in proton conductivity of the electrode catalyst layer.

  In the sixth invention, in particular, in the fifth invention, the ion exchange group is removed from the electrolyte resin in the region close to the surface of the metal catalyst particle by electrophilic substitution reaction.

  This method makes it possible to selectively cleave ion exchange groups having molecular chains with high electron density and low binding energy, thus improving the selectivity and reaction rate of the reaction site for ion exchange group removal reaction. Therefore, the fuel cell electrode catalyst layer can be produced efficiently.

  In particular, the seventh invention removes the ion exchange groups from the electrolyte resin in a region close to the surface of the metal catalyst particles in an extremely low humidity atmosphere in the fifth or sixth invention.

  By this method, the degree of ion dissociation of the ion exchange group of the electrolyte resin is reduced, a weak bond is formed between the ion exchange group and the ion, and the removal reaction of the ion exchange group proceeds from the weak bond part. Can be made. Thereby, it becomes possible to improve the selectivity and reaction rate of the reaction site in the ion exchange group removal reaction, and the fuel cell electrode catalyst layer can be more efficiently produced.

  In an eighth aspect of the invention, in particular, in any one of the fifth to seventh aspects of the invention, the ion exchange is performed in a state where the electrode potential of the fuel cell electrode catalyst layer is maintained at 0.3 V or less with respect to the standard hydrogen electrode. The group is removed.

  By this method, it is possible to increase the amount of reactive species generated in the ion exchange group removal reaction, and it is possible to more efficiently produce an electrode catalyst layer for a fuel cell.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a schematic configuration of an electrode catalyst layer for a fuel cell according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing manufacturing steps of the fuel cell electrode catalyst layer according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing a schematic configuration of the fuel cell according to the first embodiment of the present invention.

  As shown in FIG. 1, the fuel cell electrode catalyst layer 900 of the present embodiment includes an electrode catalyst 500 in which metal catalyst particles 400 are supported on the surface of carrier particles 300, and an electrolyte resin 800. . The fuel cell electrode catalyst layer 900 is formed on the surface of the gas diffusion layer 40.

  The electrolyte resin 800 is composed of an electrolyte resin 600 having a relatively low ion exchange group concentration and an electrolyte resin 700 having a relatively high ion exchange group concentration.

  Here, the fuel cell electrode catalyst layer 900, the manufacturing method thereof, and the fuel cell 100 using the fuel cell electrode catalyst layer 900 in the present embodiment will be described in more detail.

  First, the fuel cell electrode catalyst layer 900 will be described.

  In the fuel cell electrode catalyst layer 900, the surfaces of the metal catalyst particles 400 and the carrier particles 300 of the electrode catalyst 500 are coated with an electrolyte resin 800. In addition, the electrolyte resin 600 coated in the vicinity of the surface of the metal catalyst particles 400 has a lower ion exchange group concentration than the electrolyte resin 700 coated on the surface of the carrier particles 300 and the metal catalyst particles 400 far away.

In the present embodiment, carbon particles are used for the carrier particles 300, and platinum-cobalt alloy catalyst particles are used for the metal catalyst particles 400. The platinum-cobalt alloy catalyst particles include carbon particles 52
A platinum-cobalt alloy catalyst-supported carbon supported by wt% is used.

  Further, perfluorosulfonic acid is used for the electrolyte resin 700 coated on the surface of the carrier particles 300 and the metal catalyst particles 400, and a sulfonic acid group is used for the ion exchange group. The electrolyte resin 600 coated in the vicinity of the surface of the metal catalyst particles 400 is obtained by removing a part of ion exchange groups from the perfluorosulfonic acid of the electrolyte resin 700.

The molar concentration of the ion exchange groups of the electrolyte resin 700 coated on the surface of the metal catalyst particles 400 and the carrier particles 300 is 200 mol / m ³ . Further, the molar concentration of the ion exchange group amount of the electrolyte resin 600 coated in the vicinity of the surface of the metal catalyst particle 400 is 40 mol / m ³ .

The amount of the electrolyte resin 800 is the same as that of the carrier particles 300. Carbon gas is used for the gas diffusion layer 40. The area of the gas diffusion layer 40 is 200 cm ² . The supported amount of the electrode catalyst 500 is 0.1 mg / cm ² in terms of platinum per area of the gas diffusion layer 40.

  Next, the manufacturing method of the electrode catalyst layer 900 for fuel cells is demonstrated.

  As shown in FIG. 2, in the method of manufacturing the fuel cell electrode catalyst layer 900 of the present embodiment, first, in S10, the electrode catalyst 500, the electrolyte resin 700, and the mixed solvent are weighed. As the mixed solvent, a mixed solvent of water and ethanol (water: ethanol = 1: 1) is used.

  Next, in S20, the electrode catalyst 500, the electrolyte resin 700, and the mixed solvent are dispersed and mixed to produce a catalyst ink. Next, in S30, the catalyst ink is applied to the gas diffusion layer 40 and dried to coat the surface of the electrode catalyst 500 with the electrolyte resin 700. Next, the gas diffusion layer 40 to which the catalyst ink is applied in S40 is placed in a vacuum container and decompressed.

  Next, in S50, it is confirmed whether the pressure in the vacuum vessel is 25 ° C. and the absolute pressure is reduced to 0.5 bar or less. As a result of the confirmation in S50, if it is not lower than 0.5 bar, the process returns to S50 again, and if it is lower than 0.5 bar, the process proceeds to S60.

Finally, hydrogen gas containing 4% oxygen gas is supplied at a gas flow rate of 0.1 L / min for 1 minute to the gas diffusion layer 40 coated with the catalyst ink in a vacuum vessel to cover the vicinity of the surface of the metal catalyst particles 400. By removing a part of the ion exchange groups from the electrolyte resin 700, the production of the fuel cell electrode catalyst layer 900 having the electrolyte resin 600 having an ion exchange group concentration of 40 mol / m ³ is completed.

  The reaction for removing the ion exchange group of S60 will be described in more detail.

  First, hydrogen peroxide is formed by reacting hydrogen and oxygen on the surfaces of the metal catalyst particles 400. Next, the formed hydrogen peroxide reacts with cobalt ions existing in the vicinity of the surface of the metal catalyst particles 400, thereby forming hydroxyl radicals that are reactive species for the electrophilic substitution reaction.

  This hydroxyl radical is very reactive and has a feature of reacting with a molecular chain having a high electron density and a low binding energy.

The perfluorosulfonic acid used as the electrolyte resin 700 has a low bond energy between carbon and sulfur and a bond energy between oxygen and hydrogen of the sulfonic acid group which is an ion exchange group, and therefore hydroxyl radicals are present at these reaction sites. By attacking, the sulfonic acid group can be cleaved from the electrolyte resin 700.

  The ion exchange groups cleaved from the electrolyte resin 700 are dissolved in condensed water in the power generation environment of the fuel cell and discharged as sulfate ions to the outside of the fuel cell.

  Next, the fuel cell 100 using the fuel cell electrode catalyst layer 900 will be described.

  As shown in FIG. 3, in the fuel cell 100 of the present embodiment, an electrolyte membrane-electrode assembly 90, an anode separator 70a, and a cathode separator 70b are stacked.

  A fuel gas channel 71a is provided on the surface of the anode separator 70a facing the electrolyte membrane-electrode assembly 90. Similarly, an oxidant gas flow path 71b is provided on the surface of the cathode separator 70b facing the electrolyte membrane-electrode assembly 90. Carbon separators are used for the anode separator 70a and the cathode separator 70b.

  The electrolyte membrane-electrode assembly 90 includes an electrolyte membrane 10, an anode 60a that sandwiches the electrolyte membrane 10, and a cathode 60b. As the electrolyte membrane 10, a perfluorosulfonic acid membrane is used. The anode 60 a is composed of a fuel cell electrode catalyst layer 900 and a gas diffusion layer 40. The cathode 60 b is composed of a fuel cell electrode catalyst layer 900 and a gas diffusion layer 40.

In the electrolyte membrane-electrode assembly 90, the anode 60 a and the cathode 60 b are bonded to the electrolyte membrane 10 by thermocompression bonding at 120 ° C. and 10 kgf / cm ² in a state where the anode 60 a and the cathode 60 b are laminated on the electrolyte membrane 10. Use a bonded one.

  The fuel cell 100 generates power by a reaction between the fuel gas supplied to the anode 60a and the oxidant gas supplied to the cathode 60b. Hydrogen gas is used as the fuel gas, and air is used as the oxidant gas.

  As described above, the fuel cell electrode catalyst layer 900 according to the first embodiment includes the metal catalyst particles 400 including the electrode catalyst 500 in which the metal catalyst particles 400 are supported on the carrier particles 300 and the electrolyte resin 800. The surface of the carrier particle 300 is coated with the electrolyte resin 800, and the concentration of the ion exchange groups in the electrolyte resin 600 in the region close to the surface of the metal catalyst particle 400 is in the region covering the surface of the carrier particle 300. It is characterized by being lower than the concentration of the ion exchange group.

  Thereby, the concentration of the ion exchange group of the electrolyte resin 600 coated in the vicinity of the surface of the metal catalyst particle 400 without lowering the concentration and water content of the ion exchange group of the electrolyte resin 700 coated on the surface of the carrier particle 300. Only can be lowered. Further, the ion exchange group of the electrolyte resin 800 can be prevented from coming into contact with the metal catalyst particles 400, and ionization of the metal catalyst particles 400 can be reduced.

  As a result, it is possible to improve the durability of the metal catalyst particles 400 while suppressing a decrease in proton conductivity of the fuel cell electrode catalyst layer 900. In addition, by forming the fuel cell 100 using the fuel cell electrode catalyst layer 900 of the present embodiment, it is possible to provide the fuel cell 100 with low proton conduction resistance and high durability of the electrode catalyst 500. it can.

Further, in the method of manufacturing the fuel cell electrode catalyst layer 900 of the present embodiment, the electrode catalyst 500 having the metal catalyst particles 400 supported on the carrier particles 300 is coated with the electrolyte resin 700 having ion exchange groups, The concentration of ion exchange groups in the electrolyte resin 600 in the region close to the surface of the metal catalyst particle 400 is obtained by removing the ion exchange groups from the electrolyte resin 700 in the region close to the surface of the catalyst particle 400 by electrophilic substitution reaction. Is lower than the concentration of ion exchange groups in the electrolyte resin 700 in the region covering the surface of the carrier particle 300.

  Thereby, ion exchange groups are removed only from the electrolyte resin 600 in the region close to the surface of the metal catalyst particle 400, and the thickness of the electrolyte resin 600 having a low proton conductivity on the surface of the metal catalyst particle 400 can be reduced. .

  Thereby, it is possible to further suppress the decrease in proton conductivity of the fuel cell electrode catalyst layer 900. Further, by using an electrophilic substitution reaction, an ion exchange group having a molecular chain having a high electron density and a low binding energy can be selectively cleaved. The selectivity and reaction rate can be improved, and the fuel cell electrode catalyst layer 900 can be efficiently produced.

  In the present embodiment, carbon particles are used for carrier particles 300, but oxide particles can also be used in addition to this.

  In the present embodiment, platinum cobalt alloy catalyst particles are used as the metal catalyst particles 400, but other than this, platinum, ruthenium, palladium, iron, copper, chromium, cobalt, nickel, manganese, etc. Metals and alloys thereof can be used.

  In this embodiment, perfluorosulfonic acid is used for the electrolyte resin 700, but in addition to this, an electrolyte resin containing a fluorine compound introduced with an ion exchange group other than a sulfonic acid group or a hydrocarbon is used. It is also possible to use an electrolyte resin into which an ion exchange group other than a sulfonic acid group or a sulfonic acid group is introduced.

  In addition, although the perfluorosulfonic acid film | membrane was used for the electrolyte membrane 10, electrolyte membranes, such as a hydrocarbon electrolyte membrane, can also be used besides this.

  In the embodiment, carbon paper is used for the gas diffusion layer 40. However, other than this, carbon felt, carbon cloth, or the like can also be used.

  In this embodiment, hydrogen gas and oxygen gas are used in the manufacturing process for removing the ion exchange groups. However, in addition to this, an oxidizing substance and a reducing substance that can form hydrogen peroxide may be used. it can.

  In the present embodiment, the hydroxyl radical is used in the production process for removing the ion exchange group, but other electrophilic species may be used.

(Embodiment 2)
FIG. 4 is a cross-sectional view showing a schematic configuration of an electrode catalyst layer for a fuel cell according to Embodiment 2 of the present invention. FIG. 5 is a flowchart showing manufacturing steps of the fuel cell electrode catalyst layer according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a schematic configuration of the fuel cell according to the second embodiment of the present invention.

  As shown in FIG. 4, the fuel cell electrode catalyst layer 901 of this embodiment includes an electrode catalyst 500 in which metal catalyst particles 400 are supported on the surface of carrier particles 300, and an electrolyte resin 801. . The fuel cell electrode catalyst layer 901 is formed on the surface of the electrolyte membrane 11.

  The electrolyte resin 801 includes an electrolyte resin 601 having a relatively low ion exchange group concentration and an electrolyte resin 700 having a relatively high ion exchange group concentration.

  Here, the fuel cell electrode catalyst layer 901, the manufacturing method thereof, and the fuel cell 101 using the fuel cell electrode catalyst layer 901 in the present embodiment will be described in more detail.

  First, the fuel cell electrode catalyst layer 901 will be described.

  In the fuel cell electrode catalyst layer 901, the surfaces of the metal catalyst particles 400 and the carrier particles 300 of the electrode catalyst 500 are coated with an electrolyte resin 801.

  In addition, the electrolyte resin 601 coated in the vicinity of the surface of the metal catalyst particle 400 has a lower ion exchange group concentration than the electrolyte resin 700 coated in the distance from the surface of the carrier particle 300 and the metal catalyst particle 400. In addition, the electrolyte resin 601 coated in the vicinity of the surface of the metal catalyst particle 400 does not have an ion exchange group. In addition, the electrolyte resin 601 coated in the vicinity of the surface of the metal catalyst particles 400 has water repellency.

  Carbon particles are used for the carrier particles 300, and platinum-cobalt alloy catalyst particles are used for the metal catalyst particles 400. The platinum-cobalt alloy catalyst particles are platinum-cobalt alloy catalyst-supported carbon that is supported by 52 wt% on carbon particles. Perfluorosulfonic acid is used for the electrolyte resin 700 coated on the surface of the carrier particles 300 and the metal catalyst particles 400, and the ion exchange group is a sulfonic acid group.

  The electrolyte resin 601 coated in the vicinity of the surface of the metal catalyst particle 400 is obtained by removing ion exchange groups from perfluorosulfonic acid of the electrolyte resin 700. By removing the ion exchange group from the perfluorosulfonic acid of the electrolyte resin 700, the hydrophobic main chain and the side chain remain, so that the electrolyte resin 601 can be provided with water repellency.

  The amount of the electrolyte resin 801 is the same as that of the carrier particles 300.

As the electrolyte membrane 11, a perfluorosulfonic acid membrane is used. The area of the electrolyte membrane 11 is 200 cm ² . The supported amount of the electrode catalyst 500 is 0.1 mg / cm ² in terms of platinum per area of the electrolyte membrane 11.

  Next, the manufacturing method of the electrode catalyst layer 901 for fuel cells is demonstrated.

  As shown in FIG. 5, in the method of manufacturing the fuel cell electrode catalyst layer 901 of the present embodiment, first, in S11, the electrode catalyst 500, the electrolyte resin 700, and the mixed solvent are weighed. As the mixed solvent, a mixed solvent of water and ethanol (water: ethanol = 1: 1) is used.

  Next, in S21, the electrode catalyst 500, the electrolyte resin 700, and the mixed solvent are dispersed and mixed to produce a catalyst ink. Next, the catalyst ink is applied to the electrolyte membrane 11 in S31 and dried to coat the surface of the electrode catalyst 500 with the electrolyte resin 700.

  Next, the electrolyte membrane 11 to which the catalyst ink is applied in S41 is put in a vacuum container and decompressed. Next, in order to maintain an extremely low humidity atmosphere in S51, it is confirmed whether the pressure in the vacuum vessel is 60 ° C. and the absolute pressure is reduced to 0.5 bar or less. If the result of the confirmation in S51 is not lower than 0.5 bar, the process returns to S51 again, and if lower than 0.5 bar, the process proceeds to S61.

Finally, the electrolyte resin 11 coated with catalyst ink in a vacuum vessel is supplied with hydrogen gas containing 4% of oxygen gas at 0.1 L / min for 3 minutes, and the electrolyte resin coated in the vicinity of the surface of the metal catalyst particles 400 By removing the ion exchange groups from 700, the production of the fuel cell electrode catalyst layer 901 having the electrolyte resin 601 with the ion exchange group concentration of 0 mol / m ³ is completed.

  The reaction for removing the ion exchange group of S81 will be described in more detail.

  First, hydrogen peroxide is formed by reacting hydrogen and oxygen on the surfaces of the metal catalyst particles 400. Next, the formed hydrogen peroxide reacts with cobalt ions existing in the vicinity of the surface of the metal catalyst particles 400, thereby forming hydroxyl radicals that are reactive species for the electrophilic substitution reaction.

  This hydroxyl radical is very reactive and has a feature of reacting with a molecular chain having a high electron density and a low binding energy.

  The perfluorosulfonic acid used as the electrolyte resin 700 has a weak bond energy between the carbon-sulfur bond and the oxygen-hydrogen bond of the sulfonic acid group, which is an ion exchange group. When the hydroxyl radical attacks, the sulfonic acid group can be cleaved from the electrolyte resin 700.

  In addition, by maintaining the electrolyte membrane 11 coated with the catalyst ink in an extremely low humidity atmosphere, the degree of dissociation of protons of the sulfonic acid group is reduced, and the bond between oxygen and hydrogen is increased, and the bond energy is weak. The ion-exchange group removal reaction can proceed with the weak binding moiety as a starting point.

  This makes it possible to improve the selectivity and reaction rate of the reaction site in the ion exchange group removal reaction, and the fuel cell electrode catalyst layer 901 can be manufactured more efficiently.

  Next, the fuel cell 101 using the fuel cell electrode catalyst layer 901 will be described.

  As shown in FIG. 6, in the fuel cell 101 of the present embodiment, an electrolyte membrane-electrode assembly 91, an anode separator 70a, and a cathode separator 70b are laminated.

  A fuel gas passage 71a is provided on the surface of the anode separator 70a facing the electrolyte membrane-electrode assembly 91. Similarly, an oxidant gas flow path 71b is provided on the surface of the cathode separator 70b facing the electrolyte membrane-electrode assembly 91. A carbon separator is used for the anode separator 70a and the cathode separator 70b.

The anode 61 a is composed of a fuel cell electrode catalyst layer 901 and a gas diffusion layer 41. The cathode 61 b includes a fuel cell electrode catalyst layer 901 and a gas diffusion layer 41. Carbon gas is used for the gas diffusion layer 41. The area of the gas diffusion layer 41 is 200 cm ² .

The electrolyte membrane-electrode assembly 91 is thermocompression bonded at 120 ° C. and 10 kgf / cm ² with the electrolyte membrane 11 having the fuel cell electrode catalyst layer 901 formed on both sides thereof laminated on the gas diffusion layer 41. Thus, the gas diffusion layer 41 bonded to the fuel cell electrode catalyst layer 901 is used.

  The fuel cell 101 generates power by a reaction between a fuel gas supplied to the anode 61a and an oxidant gas supplied to the cathode 61b. Hydrogen gas is used as the fuel gas, and air is used as the oxidant gas.

  As described above, the fuel cell electrode catalyst layer 901 of the second embodiment includes the electrode catalyst 500 in which the metal catalyst particles 400 are supported on the carrier particles 300 and the electrolyte resin 801. The surface of the carrier particle 300 is coated with the electrolyte resin 801, and the concentration of the ion exchange group of the electrolyte resin 601 in the region close to the surface of the metal catalyst particle 400 is in the region covering the surface of the carrier particle 300. The electrolyte resin 601 in the region adjacent to the surface of the metal catalyst particle 400 does not have an ion exchange group.

  Thereby, the concentration of the ion exchange group of the electrolyte resin 601 coated in the vicinity of the surface of the metal catalyst particle 400 without reducing the concentration and water content of the ion exchange group of the electrolyte resin 700 coated on the surface of the carrier particle 300. Only can be lowered. Further, the ion exchange group of the electrolyte resin 800 can be prevented from coming into contact with the metal catalyst particles 400, and ionization of the metal catalyst particles 400 can be further reduced.

  Further, adsorption of ion exchange groups of the electrolyte resin 601 on the surface of the metal catalyst particles 400 can be eliminated, and the effective reaction sites of the metal catalyst particles 400 can be increased. As a result, it is possible to improve the durability and catalytic activity of the metal catalyst particles 400 while suppressing a decrease in proton conductivity of the fuel cell electrode catalyst layer 900.

  In addition, since the electrolyte resin 601 in the region close to the surface of the metal catalyst particle 400 has water repellency, the moisture content of the electrolyte resin 601 in the region close to the surface of the metal catalyst particle 400 can be reduced.

  Thereby, the oxidation of the metal catalyst particles 400 by water can be suppressed, and the durability of the metal catalyst particles 400 can be further improved. Further, by configuring the fuel cell 101 using the fuel cell electrode catalyst layer 901 of the present embodiment, the fuel cell 101 having low proton conduction resistance and reaction resistance and high durability of the electrode catalyst 500 is provided. can do.

  Further, in the method of manufacturing the fuel cell electrode catalyst layer 901 of the present embodiment, the electrode catalyst 500 having the metal catalyst particles 400 supported on the carrier particles 300 is coated with the electrolyte resin 700 having ion exchange groups, The concentration of ion exchange groups in the electrolyte resin 601 in the region close to the surface of the metal catalyst particle 400 is obtained by removing the ion exchange groups from the electrolyte resin 700 in the region close to the surface of the catalyst particle 400 by electrophilic substitution reaction. Is lower than the concentration of ion exchange groups in the electrolyte resin 700 in the region covering the surface of the carrier particle 300.

  Thereby, the ion exchange group can be removed only from the electrolyte resin 601 in the region close to the surface of the metal catalyst particle 400. As a result, the thickness of the electrolyte resin 601 having a low proton conductivity on the surface of the metal catalyst particles 400 can be reduced, and a decrease in the proton conductivity of the fuel cell electrode catalyst layer 901 can be further suppressed.

  Further, by using an electrophilic substitution reaction, an ion exchange group having a molecular chain having a high electron density and a low binding energy can be selectively cleaved. The selectivity and reaction rate can be improved.

  Thereby, the electrode catalyst layer 901 for fuel cells can be manufactured efficiently. Further, by removing the ion exchange group in an atmosphere of extreme humidity, the degree of ion dissociation of the ion exchange group of the electrolyte resin 700 is reduced, and a weak bond is formed between the ion exchange group and the ion. Starting from the portion, the ion exchange group removal reaction can proceed.

  Thereby, the selectivity of the reaction site and the reaction rate in the ion exchange group removal reaction can be improved, and the fuel cell electrode catalyst layer 901 can be manufactured more efficiently.

  In this embodiment, carbon particles are used for carrier particles 300, but oxide particles can also be used in addition to this.

  In the present embodiment, platinum cobalt alloy catalyst particles are used as the metal catalyst particles 400, but other than this, platinum, ruthenium, palladium, iron, copper, chromium, cobalt, nickel, manganese, etc. Metals and alloys thereof can be used.

  In this embodiment, the perfluorosulfonic acid group is used for the electrolyte resin 700, but in addition to this, an electrolyte resin including a fluorine compound introduced with an ion exchange group other than the sulfonic acid group, or a hydrocarbon, It is also possible to use an electrolyte resin into which an ion exchange group other than a sulfonic acid group or a sulfonic acid group is introduced.

  In addition, although the perfluorosulfonic acid film | membrane was used for the electrolyte membrane 11, electrolyte membranes, such as a hydrocarbon electrolyte membrane, can also be used besides this.

  In the embodiment, carbon paper is used for the gas diffusion layer 41. However, other than this, carbon felt, carbon cloth, or the like can also be used.

  In this embodiment, hydrogen gas and oxygen gas are used in the manufacturing process for removing the ion exchange groups. However, in addition to this, an oxidizing substance and a reducing substance that can form hydrogen peroxide may be used. it can.

  In the present embodiment, the hydroxyl radical is used in the production process for removing the ion exchange group, but other electrophilic species may be used.

(Embodiment 3)
FIG. 7: is sectional drawing which shows schematic structure of the electrode catalyst layer for fuel cells concerning Embodiment 3 of this invention. FIG. 8 is a flowchart showing manufacturing steps of the fuel cell electrode catalyst layer according to the third embodiment of the present invention. FIG. 9: is sectional drawing which shows schematic structure of the electrochemical cell used for the manufacturing process of the electrode catalyst layer for fuel cells concerning Embodiment 3 of this invention. FIG. 10 is a cross-sectional view showing a schematic configuration of the fuel cell according to the third embodiment of the present invention.

  As shown in FIG. 7, the fuel cell electrode catalyst layer 902 of this embodiment includes an electrode catalyst 500 in which metal catalyst particles 400 are supported on the surfaces of carrier particles 300, and an electrolyte resin 802. . The fuel cell electrode catalyst layer 902 is formed on the surface of the gas diffusion layer 42.

  The electrolyte resin 802 includes an electrolyte resin 602 having a relatively low ion exchange group concentration and an electrolyte resin 702 having a relatively high ion exchange group concentration.

  Here, the fuel cell electrode catalyst layer 902, the manufacturing method thereof, and the fuel cell 102 using the fuel cell electrode catalyst layer 902 in the present embodiment will be described in more detail.

  First, the fuel cell electrode catalyst layer 902 will be described.

In the fuel cell electrode catalyst layer 902, the surfaces of the metal catalyst particles 400 and the carrier particles 300 of the electrode catalyst 500 are coated with an electrolyte resin 802.

  In addition, the electrolyte resin 602 coated in the vicinity of the surface of the metal catalyst particle 400 has a lower ion exchange group concentration than the electrolyte resin 702 coated in the distance from the surface of the carrier particle 300 and the metal catalyst particle 400. In addition, the electrolyte resin 602 coated in the vicinity of the surface of the metal catalyst particles 400 does not have an ion exchange group.

  The electrolyte resin 602 coated near the surface of the metal catalyst particle 400 has water repellency, whereas the electrolyte resin 702 coated near the surface of the carrier particle 300 has hydrophilicity.

  Carbon particles are used for the carrier particles 300, and platinum-cobalt alloy catalyst particles are used for the metal catalyst particles 400. The platinum-cobalt alloy catalyst particles are platinum-cobalt alloy catalyst-supported carbon that is supported by 52 wt% on carbon particles. Perfluorosulfonic acid is used for the electrolyte resin 702 coated on the surface of the carrier particles 300 and the metal catalyst particles 400, and the ion exchange group is a sulfonic acid group.

  The electrolyte resin 602 coated in the vicinity of the surface of the metal catalyst particles 400 is obtained by removing ion exchange groups from perfluorosulfonic acid of the electrolyte resin 702. By removing the ion exchange groups from the perfluorosulfonic acid of the electrolyte resin 702, the hydrophobic main chain and side chains remain, so that the water repellency of the electrolyte resin 602 can be improved.

The molar concentration of the ion exchange group of the electrolyte resin 702 coated on the surface of the carrier particles 300 and the metal catalyst particles 400 is 305 mol / m ³ . By increasing the molar concentration of the ion exchange group of the electrolyte resin 702, the amount of water coordinated to the ion exchange group is increased, and the hydrophilicity of the electrolyte resin 702 can be improved.

The molar concentration of the ion exchange group amount of the electrolyte resin 602 coated in the vicinity of the surface of the metal catalyst particle 400 is 0 mol / m ³ . The amount of the electrolyte resin 802 is the same as that of the carrier particles 300.

The area of the gas diffusion layer 42 made of carbon paper is 200 cm ² . The supported amount of the electrode catalyst 500 is 0.1 mg / cm ² in terms of platinum per area of the gas diffusion layer 42.

  Next, a method for producing the fuel cell electrode catalyst layer 902 will be described.

  As shown in FIG. 8, in the method of manufacturing the fuel cell electrode catalyst layer 902 of this embodiment, first, in S12, the electrode catalyst 500, the electrolyte resin 702, and the mixed solvent are weighed. As the mixed solvent, a mixed solvent of water and ethanol (water: ethanol = 1: 1) is used.

  Next, in S22, the electrode catalyst 500, the electrolyte resin 702, and the mixed solvent are dispersed and mixed to produce a catalyst ink. Next, in S32, the catalyst ink is applied to the gas diffusion layer 42 and dried to coat the surface of the electrode catalyst 500 with the electrolyte resin 702.

  Next, as shown in FIG. 10, the gas diffusion layer 42 applied with the catalyst ink in S <b> 42 is set in the electrochemical cell 8 as the working electrode 4. The electrochemical cell 8 includes a 1 mol / L perchloric acid electrolytic solution as the electrolytic solution 3, a standard hydrogen electrode composed of a platinum mesh electrode as the reference electrode 7, and a platinum mesh electrode as the counter electrode 5.

  The reference electrode 7 is installed in a reference electrode container 6 filled with hydrogen. Next, oxygen gas is supplied from the gas supply path 2 to the electrochemical cell 8 at 0.2 L / min in S52.

Finally, with the oxygen gas supplied at 0.2 L / min in S62, the electrode of the working electrode 4 of the gas diffusion layer 42 to which the catalyst ink is applied to the reference electrode 7 using the electrochemical control device 1 An electrolyte resin in which the concentration of the ion exchange groups becomes 0 mol / m ³ by removing the ion exchange groups from the electrolyte resin 702 coated in the vicinity of the surface of the metal catalyst particles 400 while maintaining the potential at 0.3 V for 30 seconds. The production of the fuel cell electrode catalyst layer 902 having 602 is completed.

  The reaction for removing the ion exchange group of S62 will be described in more detail.

  First, in a state where oxygen is supplied, the electrode potential of the working electrode 4 of the gas diffusion layer 42 to which the catalyst ink is applied in the perchloric acid electrolyte is maintained at 0.3 V with respect to the standard hydrogen electrode. Hydrogen and oxygen are reacted on the surface of the catalyst particle 400 to form hydrogen peroxide.

  Next, the formed hydrogen peroxide reacts with cobalt ions existing in the vicinity of the surface of the metal catalyst particles 400, thereby forming hydroxyl radicals that are reactive species for the electrophilic substitution reaction. This hydroxyl radical is very reactive and has a feature of reacting with a molecular chain having a high electron density and a low binding energy.

  The perfluorosulfonic acid used as the electrolyte resin 702 has a weak bond energy between carbon and sulfur of the sulfonic acid group which is an ion exchange group, and between oxygen and hydrogen. Can attack the sulfonic acid group from the electrolyte resin 702.

  In addition, by maintaining the standard hydrogen electrode at 0.3 V, the amount of hydrogen adsorbed on the surface of the metal catalyst particles 400 increases, and the amount of hydrogen peroxide generated can be increased. In addition, since the working electrode 4 has a potential lower than the oxidation-reduction potential of hydrogen peroxide, the reaction in which hydrogen peroxide is decomposed and becomes water by the metal catalyst particles 400 can be suppressed.

  As a result, the amount of reactive species in the ion exchange group removal reaction on the surface of the metal catalyst particle 400 can be increased, so that the reaction rate in the ion exchange group removal reaction can be improved. The fuel cell electrode catalyst layer 902 can be efficiently produced.

  Next, the fuel cell 102 using the fuel cell electrode catalyst layer 902 will be described.

  As shown in FIG. 10, in the fuel cell 102 of the present embodiment, an electrolyte membrane-electrode assembly 92, an anode separator 70a, and a cathode separator 70b are laminated.

  A fuel gas flow path 71a is provided on the surface of the anode separator 70a facing the electrolyte membrane-electrode assembly 92. Similarly, an oxidant gas flow path 71b is provided on the surface of the cathode separator 70b facing the electrolyte membrane-electrode assembly 91. A carbon separator is used for the anode separator 70a and the cathode separator 70b.

  The electrolyte membrane-electrode assembly 91 includes an electrolyte membrane 12, an anode 62a that sandwiches the electrolyte membrane 12, and a cathode 62b. The electrolyte membrane 12 uses a perfluorosulfonic acid membrane. Further, the anode 62 a is composed of a fuel cell electrode catalyst layer 902 and a gas diffusion layer 42. The cathode 62 b is composed of a fuel cell electrode catalyst layer 902 and a gas diffusion layer 42.

In the electrolyte membrane-electrode assembly 92, the anode 62 a and the cathode 62 b are bonded to the electrolyte membrane 12 by thermocompression bonding at 140 ° C. and 10 kgf / cm ² in a state where the anode 62 a and the cathode 62 b are laminated on the electrolyte membrane 10. Use a bonded one.

  The fuel cell 102 generates power by a reaction between the fuel gas supplied to the anode 62a and the oxidant gas supplied to the cathode 62b. Hydrogen gas is used as the fuel gas, and air is used as the oxidant gas.

  As described above, the fuel cell electrode catalyst layer 902 of the third embodiment includes the electrode catalyst 500 in which the metal catalyst particles 400 are supported on the carrier particles 300 and the electrolyte resin 802. The surface of the carrier particle 300 is coated with the electrolyte resin 802, and the concentration of the ion exchange group of the electrolyte resin 602 in the region close to the surface of the metal catalyst particle 400 is in the region covering the surface of the carrier particle 300. The electrolyte resin 602 in the region close to the surface of the metal catalyst particle 400 does not have an ion exchange group.

  Thereby, the concentration of the ion exchange group of the electrolyte resin 602 coated in the vicinity of the surface of the metal catalyst particle 400 without reducing the concentration and water content of the ion exchange group of the electrolyte resin 702 coated on the surface of the carrier particle 300. Only can be lowered.

  In addition, the ion exchange group of the electrolyte resin 802 can be prevented from coming into contact with the metal catalyst particles 400, and ionization of the metal catalyst particles 400 can be further reduced. Further, adsorption of ion exchange groups of the electrolyte resin 602 on the surface of the metal catalyst particles 400 can be eliminated, and the effective reaction sites of the metal catalyst particles 400 can be increased.

  As a result, the durability and catalytic activity of the metal catalyst particles 400 can be improved while suppressing a decrease in proton conductivity of the electrode catalyst layer 902 for the fuel cell.

  Further, the electrolyte resin 602 in the region close to the surface of the metal catalyst particle 400 has water repellency, thereby reducing the water content of the electrolyte resin 602 in the region close to the surface of the metal catalyst particle 400. Thereby, the oxidation of the metal catalyst particles 400 by water can be suppressed, and the durability of the metal catalyst particles 400 can be further improved.

  Further, since the electrolyte resin 702 in the region covering the surface of the carrier particle 300 has hydrophilicity, the water content on the surface of the carrier particle 300 increases, the proton diffusion path increases, and the fuel cell electrode It is possible to further suppress a decrease in proton conductivity of the catalyst layer 902.

  Further, by forming the fuel cell 102 using the fuel cell electrode catalyst layer 902 of the present embodiment, the fuel cell 102 having low proton conduction resistance and reaction resistance and high durability of the electrode catalyst 500 is provided. can do.

  Furthermore, in the method of manufacturing the fuel cell electrode catalyst layer 902 of the present embodiment, the electrode catalyst 500 having the metal catalyst particles 400 supported on the carrier particles 300 is coated with the electrolyte resin 702 having ion exchange groups, By removing the ion exchange groups from the electrolyte resin 702 in the region close to the surface of the catalyst particles by an electrophilic substitution reaction, the concentration of the ion exchange groups in the electrolyte resin 602 in the region close to the surface of the metal catalyst particles 400 is reduced. The concentration of the ion exchange group in the electrolyte resin 702 in the region covering the surface of the carrier particle 300 is reduced.

Thereby, the thickness of the electrolyte resin 602 having a low proton conductivity on the surface of the metal catalyst particle 400 can be reduced by removing the ion exchange groups only from the electrolyte resin 702 in the region close to the surface of the metal catalyst particle 400. It is possible to further suppress the decrease in proton conductivity of the fuel cell electrode catalyst layer 902.

  In addition, by using an electrophilic substitution reaction, an ion exchange group having a molecular chain with a high electron density and a low binding energy can be selectively cleaved, and the selectivity and reaction of the reaction site of the ion exchange group removal reaction The speed can be improved. Thereby, the electrode catalyst layer 902 for fuel cells can be manufactured efficiently.

  Further, the ion exchange groups on the surface of the metal catalyst particles 400 are removed by removing the ion exchange groups while maintaining the electrode potential of the fuel cell electrode catalyst layer at 0.3 V or less with respect to the standard hydrogen electrode. It is possible to increase the amount of reaction species generated in the removal reaction. Thereby, since the reaction rate in the ion-exchange group removal reaction can be improved, the fuel cell electrode catalyst layer 902 can be manufactured more efficiently.

  In the present embodiment, carbon particles are used for carrier particles 300, but oxides can also be used in addition to these.

  In the present embodiment, platinum cobalt alloy catalyst particles are used as the metal catalyst particles 400, but other than this, platinum, ruthenium, palladium, iron, copper, chromium, cobalt, nickel, manganese, etc. Metals and alloys thereof can be used.

  In this embodiment, perfluorosulfonic acid is used for the electrolyte resin 702. However, in addition to this, an electrolyte resin containing a fluorine compound introduced with an ion exchange group other than a sulfonic acid group or a hydrocarbon is used. It is also possible to use an electrolyte resin into which an ion exchange group other than a sulfonic acid group or a sulfonic acid group is introduced.

  In addition, although the perfluorosulfonic acid film | membrane was used for the electrolyte membrane 12, electrolyte membranes, such as a hydrocarbon electrolyte membrane, can also be used besides this.

  In the embodiment, carbon paper is used for the gas diffusion layer 42. However, other than this, carbon felt, carbon cloth, or the like can also be used.

  In the present embodiment, the perchloric acid electrolytic solution is used in the production process for removing the ion exchange groups. However, in addition to this, an electrolytic solution capable of ionizing protons or a perfluorosulfonic acid membrane It can also be used as an electrolyte membrane.

  In this embodiment, hydrogen gas and oxygen gas are used in the manufacturing process for removing the ion exchange groups. However, in addition to this, an oxidizing substance and a reducing substance that can form hydrogen peroxide may be used. it can.

  In this embodiment, the potential holding condition of the working electrode in the manufacturing process for removing the ion exchange group is 0.3 V with respect to the standard hydrogen electrode, but the potential range is from 0.3 V to 0.05 V. It can also be set to either.

  In this embodiment, the potential holding condition of the working electrode in the manufacturing process for removing the ion exchange group is 0.3 V with respect to the standard hydrogen electrode, but 0.3 V with respect to the anode saturated with hydrogen. You can also

In the present embodiment, the hydroxyl radical is used in the production process for removing the ion exchange group, but other electrophilic species may be used.

  As described above, the electrode catalyst layer for a fuel cell according to the present invention can improve the durability of the metal catalyst particles while suppressing a decrease in proton conductivity, and the electrode catalyst for a fuel cell according to the present invention. By forming a fuel cell using layers, a fuel cell with low proton conduction resistance and reaction resistance and high durability of the electrode catalyst can be realized. Therefore, a portable power source, a power source for portable devices, a power source for electric vehicles, Applicable to home cogeneration systems.

DESCRIPTION OF SYMBOLS 1 Electrochemical control apparatus 2 Gas supply path 3 Electrolyte solution 4 Working electrode 5 Counter electrode 6 Reference electrode container 7 Reference electrode 8 Electrochemical cell 10, 11, 12 Electrolyte membrane 40, 41, 42 Gas diffusion layer 60a, 61a, 62a Anode 60b , 61b, 62b Cathode 70a Anode separator 70b Cathode separator 71a Fuel gas flow path 71b Oxidant gas flow path 90, 91, 92 Electrolyte membrane-electrode assembly 100, 101, 102 Fuel cell 300 Carrier particle 400 Metal catalyst particle 500 Electrocatalyst 600,601,602 Electrolyte resin 700,702 Electrolyte resin 800,801,802 Electrolyte resin 900,901,902 Electrode catalyst layer for fuel cell

Claims (8)

An electrode catalyst layer for a fuel cell composed of an electrode catalyst in which metal catalyst particles are supported on carrier particles, and an electrolyte resin,
The surface of the metal catalyst particles and the carrier particles are coated with the electrolyte resin, and the concentration of ion exchange groups of the electrolyte resin in the region close to the surface of the metal catalyst particles covers the surface of the carrier particles An electrode catalyst layer for a fuel cell, wherein the concentration is lower than the concentration of the ion exchange group of the electrolyte resin. 2. The fuel cell electrode catalyst layer according to claim 1, wherein the electrolyte resin in a region close to the surface of the metal catalyst particles does not have the ion exchange group. 3. The electrode catalyst layer for a fuel cell according to claim 1, wherein the electrolyte resin in a region adjacent to the surface of the metal catalyst particles has water repellency. The electrode catalyst layer for a fuel cell according to any one of claims 1 to 3, wherein the electrolyte resin in a region covering the surface of the carrier particles has hydrophilicity. The step of removing the ion exchange groups from the electrolyte resin in the region close to the surface of the metal catalyst particles after coating the electrode catalyst having the metal catalyst particles supported on the carrier particles with the electrolyte resin having ion exchange groups. A method for producing an electrode catalyst layer for a fuel cell, comprising: 6. The method for producing an electrode catalyst layer for a fuel cell according to claim 5, wherein the ion exchange group is removed from the electrolyte resin in a region close to the surface of the metal catalyst particle by an electrophilic substitution reaction. The production of an electrode catalyst layer for a fuel cell according to claim 5 or 6, wherein the ion-exchange group is removed from the electrolyte resin in a region close to the surface of the metal catalyst particle in an extremely low humidity atmosphere. Method. 8. The ion exchange group is removed with the electrode potential of the fuel cell electrode catalyst layer kept at 0.3 V or less with respect to a standard hydrogen electrode. The manufacturing method of the electrode catalyst layer for fuel cells as described in any one of.

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