JP2005085574A - Electrode catalyst ink, its storing method, and operation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the usable period of an electrode catalyst ink by preventing the deterioration of the electrode catalyst ink. <P>SOLUTION: This is an electrode catalyst ink used for electrode formation of a fuel cell and contains a dispersed solvent made of a lower alcohol, a catalyst powder which is dispersed in the dispersed solvent and carries a catalyst active substance in a catalyst carrier, and an optical catalyst unit (optical catalyst pellet 1) dispersed in the dispersed solvent. The electrode catalyst ink 2 is housed in a transparent glass container 11 on the inner wall of which an optical catalyst layer 13 is formed, and by stirring the electrode catalyst ink 2 by a stirring device 12, light is irradiated. Deterioration of the electrode catalyst ink 2 is suppressed by the action of the optical catalyst of the optical catalyst pellet 1 and the optical catalyst coating layer 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrode catalyst ink and a method for storing and using the same, and more particularly to an electrode catalyst ink for forming an electrode for a fuel cell and a method for storing and using the same.

  2. Description of the Related Art A fuel cell, for example, a solid polymer fuel cell, is usually composed of an electrolyte membrane made of a humidified solid polymer and a pair of electrodes (a fuel electrode and an air electrode) provided with the electrolyte membrane interposed therebetween. . These electrodes have a two-layer structure of an electrode catalyst layer in which an electrode reaction is performed and a gas diffusion layer that functions as a gas supply path to the electrode catalyst layer and a current collector. That is, the fuel electrode includes an electrode catalyst layer in which an electrode reaction of fuel gas is performed, and a gas diffusion layer that supplies fuel gas to the electrode catalyst layer and functions as a current collector. On the other hand, the air electrode includes an electrode catalyst layer in which an electrode reaction of a gas containing oxygen such as air is performed, and a gas diffusion layer that supplies a gas containing oxygen such as air to the electrode catalyst layer and functions as a current collector It consists of and. Then, hydrogen ions formed from the fuel gas by the electrode reaction in the electrode catalyst layer of the fuel electrode pass through the electrolyte membrane and move to the air electrode, and the hydrogen ions and oxygen are moved by the electrode reaction in the electrode catalyst layer of the air electrode. From this, water is discharged, and current is output.

  The electrode catalyst layer constituting the electrode of such a fuel cell is generally a catalyst comprising a conductive catalyst carrier made of carbon powder (carbon black, etc.) and the like and a catalytically active substance made of noble metal (platinum, etc.) particles. It has a structure in which the powder and hydrophobic binder particles made of a fluorine-containing compound such as PTFE (polytetrafluoroethylene) are used as constituent components and the catalyst powder is highly dispersed in the hydrophobic binder particles. In addition, an electrode catalyst layer in which the catalyst powder is highly dispersed in a solid electrolyte made of a solid polymer having proton conductivity instead of a hydrophobic binder particle, or a catalyst powder is highly dispersed in the hydrophobic binder particle and the solid electrolyte. There is also an electrode catalyst layer.

  Such an electrode catalyst layer is generally formed by printing using an electrode catalyst ink. That is, the electrode catalyst layer integrally bonded to the electrolyte membrane is formed by directly applying the electrode catalyst ink to the electrolyte membrane or hot-pressing the sheet obtained by forming the membrane from the electrode catalyst ink onto the electrolyte membrane. Is done.

As an electrode catalyst ink used for forming an electrode of this fuel cell, a catalyst powder in which platinum is supported on carbon powder is dispersed in a lower alcohol such as ethanol and a solid electrolyte is added thereto. In addition, a catalyst powder comprising platinum supported on carbon powder is dispersed in a propylene glycol aqueous solution, a solid electrolyte is added to the dispersion, and ethanol as a solvent for adjusting viscosity and water content is added thereto. An electrocatalyst ink is also known (see, for example, Patent Document 1).
JP 2001-266901 A

  However, the above-mentioned conventional electrode catalyst ink has a short usable period of about one week after production, and the ink after about one week has been discarded after production. In order to avoid the disposal of the electrode catalyst ink using expensive noble metal as a material, it is desired to make the usable period of the electrode catalyst ink as long as possible.

  The reason why the usable period of the electrode catalyst ink is short in this way is considered to be because lower alcohol such as ethanol contained as a dispersion solvent or the like is altered by oxidation. That is, lower alcohols typified by ethanol have a Pt oxide reducing action, as shown in the following formula (1). In the reaction represented by the following formula (1), it is considered that ethanol itself is oxidized to form a carboxyl group, thereby changing from ethanol to acetic acid as represented by the following formula (2).

PtO ₂ → Pt + O ₂ (1)
C ₂ H ₅ OH → CH ₃ COOH (2)

  When ethanol is altered by oxidation in this way, catalyst dispersibility is reduced due to solid-liquid separation of the catalyst ink, resulting in distribution in cast films (membranes with catalysts), and electrode performance is greatly reduced. End up. For this reason, the usable period of the electrode catalyst ink is set to about one week in order to maintain the electrode performance.

  The present invention has been made in view of the above circumstances, and it is a technical problem to be solved by suppressing the deterioration of the electrode catalyst ink used for forming the electrode of the fuel cell and extending the usable period of the electrode catalyst ink. Is.

  The electrode catalyst ink of the present invention that solves the above-mentioned problems is an electrode catalyst ink used for forming an electrode of a fuel cell, and comprises a dispersion solvent composed of a lower alcohol, and a catalyst active material dispersed in the dispersion solvent, on a catalyst carrier. It comprises a catalyst powder formed thereon and a photocatalyst dispersed in the dispersion solvent.

  Since this electrode catalyst ink contains a photocatalyst, deterioration is suppressed by the action of the photocatalyst, and the usable period becomes longer. This is presumably because the reduction effect of the lower alcohol as a dispersion solvent is suppressed by the photo-oxidation power of the photocatalyst, thereby suppressing alteration due to the oxidation of the lower alcohol.

  In addition, active oxygen having strong decomposing ability is generated by the action of the photocatalyst. Therefore, the purification action (deodorant, antibacterial, antifungal, antifouling and anticorrosion) by this active oxygen prevents the electrocatalyst ink from decaying and preventing The action of mold and deodorization is exhibited, and this also suppresses the deterioration of the electrode catalyst ink.

  The method for storing the electrode catalyst ink of the present invention that solves the above problems includes a dispersion solvent comprising a lower alcohol, a catalyst powder dispersed in the dispersion solvent and carrying a catalytically active substance on a catalyst carrier, and the dispersion solvent. A method for storing an electrode catalyst ink used for forming an electrode of a fuel cell, comprising a photocatalyst body dispersed in the electrode catalyst, wherein the electrode catalyst ink is stored in a transparent container, and the electrode catalyst is stored in the transparent container The electrode catalyst ink is irradiated with light while stirring the ink with a stirring device.

  In this electrode catalyst ink storage method, an electrode catalyst ink containing a photocatalyst is contained in a transparent container, and the electrode catalyst ink is irradiated with light while stirring the electrode catalyst ink with a stirrer. The dispersibility of the photocatalyst body in the inside is improved, and it becomes possible to irradiate all the photocatalyst bodies more evenly, and the action of the photocatalyst can be exhibited more effectively. Also, when the electrode catalyst ink is black, the photocatalyst existing inside the ink is not easily irradiated with light, but the photocatalyst is circulated by stirring, so the photocatalyst present inside the ink is removed from the ink. It can exist on the surface side of. For this reason, even if the electrode catalyst ink is black, it becomes possible to irradiate light uniformly to all the photocatalyst bodies.

  Therefore, according to the storage method of the electrode catalyst ink, the deterioration of the electrode catalyst ink can be effectively suppressed by the action of the photocatalyst, and the usable period of the electrode catalyst ink can be extended.

  In a preferred embodiment of the method for storing the electrode catalyst ink of the present invention, a transparent photocatalyst coating layer is formed on the inner wall surface of the transparent container.

  According to this aspect, since the transparent photocatalyst coat layer is formed on the inner wall surface of the transparent container containing the electrode catalyst ink, the deterioration of the electrode catalyst ink is also suppressed by the action of the photocatalyst existing in the photocatalyst coat layer. Therefore, it is possible to more effectively suppress deterioration of the electrode catalyst ink.

  The method of using the electrode catalyst ink of the present invention that solves the above problems includes a dispersion solvent comprising a lower alcohol, a catalyst powder dispersed in the dispersion solvent and carrying a catalytically active substance on a catalyst carrier, and the dispersion solvent. A method for using an electrode catalyst ink used for forming an electrode of a fuel cell, comprising a photocatalyst body dispersed in the electrode catalyst, wherein the electrode catalyst ink is stored in a transparent container, and the electrode catalyst is stored in the transparent container A storage step of irradiating the electrode catalyst ink with light while stirring the ink with a stirrer, and supplying the electrode catalyst ink to the coating part through a pipe connected to the transparent container. A coating step of coating the electrode catalyst ink on the coating, and in the coating step, the photocatalyst contained in the electrode catalyst ink is removed and then the electrode catalyst ink is applied to the coating portion. Features supplying It is intended to.

  In this method of using the electrode catalyst ink, the electrode catalyst ink containing the photocatalyst is stored in a transparent container in the storage step, and the electrode catalyst ink is irradiated with light while stirring the electrode catalyst ink with a stirring device. The dispersibility of the photocatalyst in the electrode catalyst ink is improved, and it becomes possible to irradiate all the photocatalysts more evenly, so that the action of the photocatalyst can be exhibited more effectively. Also, when the electrode catalyst ink is black, the photocatalyst existing inside the ink is not easily irradiated with light, but the photocatalyst is circulated by stirring, so the photocatalyst present inside the ink is removed from the ink. It can exist on the surface side of. For this reason, even if the electrode catalyst ink is black, it becomes possible to irradiate light uniformly to all the photocatalyst bodies. Therefore, according to this storage step, the deterioration of the electrode catalyst ink can be effectively suppressed by the action of the photocatalyst, and the usable period of the electrode catalyst ink can be extended.

  In the coating process, the photocatalyst contained in the electrode catalyst ink is removed, and then the electrode catalyst ink is supplied to the coating part. Thus, an electrode catalyst layer in which no unnecessary photocatalyst is present in the electrode catalyst layer is manufactured. can do.

  The pipe is preferably a transparent pipe.

  In a preferred embodiment of the method for using the electrode catalyst ink of the present invention, a transparent photocatalyst coat layer is formed on the inner wall surface of at least one of the transparent container and the transparent pipe.

  According to this aspect, the transparent photocatalyst coating layer is formed on at least one of the inner wall surface of the transparent container containing the electrode catalyst ink and the inner wall surface of the pipe for supplying the electrode catalyst ink from the transparent container to the coating portion. Therefore, since the deterioration of the electrode catalyst ink can also be suppressed by the action of the photocatalyst existing in these photocatalyst coat layers, the deterioration of the electrode catalyst ink can be suppressed more effectively.

  Therefore, according to the electrocatalyst ink of the present invention and its storage and use method, the photocatalyst suppresses the alteration of the lower alcohol as the dispersion solvent, and also prevents the electrocatalyst ink from being spoiled, preventing mold and deodorizing. Therefore, the deterioration of the electrode catalyst ink can be effectively suppressed, and the usable period of the electrode catalyst ink can be extended.

  Therefore, according to the electrode catalyst ink of the present invention and its storage method and method of use, cost reduction can be achieved by avoiding disposal of expensive electrode catalyst ink.

  The electrode catalyst ink according to the present invention is used for forming an electrode of a fuel cell. The type of fuel cell is not particularly limited, and can be applied to various fuel cells in which electrodes are formed using an electrode catalyst ink containing a lower alcohol as a dispersion solvent or the like, for example, a polymer electrolyte fuel cell.

  The electrode catalyst ink according to the present invention includes a dispersion solvent made of a lower alcohol, a catalyst powder dispersed in the dispersion solvent and carrying a catalytically active substance on a catalyst carrier, and a photocatalyst body dispersed in the dispersion solvent. including.

  It does not specifically limit as said lower alcohol, Ethanol, 1-propanol, 1-butanol, 1-pentanol etc. can be mentioned.

  The catalyst carrier is not particularly limited, and a conductive catalyst carrier represented by carbon particles such as carbon black can be used.

  The catalytically active substance is not particularly limited, and a noble metal powder such as platinum, iron or cobalt can be used.

The photocatalyst is not particularly limited as long as it exhibits a photocatalytic action. For example, a photocatalyst pellet having a diameter of about 5 to 30 mm obtained by pelletizing (granulating) the photocatalyst can be used, or a photocatalyst powder having a diameter of about 0.5 to 20 μm can be used as it is. The type of photocatalyst of the photocatalyst is not particularly limited as long as it does not adversely affect the catalyst powder or the like in the electrode catalyst ink. Titanium oxide, (TiO ₂ ), or titanium oxide carrying platinum (Pt / TiO ₂ ) Can be used. Here, many photocatalysts represented by titanium oxide enter a photoexcited state upon irradiation with ultraviolet rays and exhibit photooxidation power. Of course, it is possible to use a photocatalyst that exhibits photooxidation power by irradiation with ultraviolet rays, but a photocatalyst imparted with visible light responsiveness that exhibits photooxidation power even by irradiation with visible light (ultraviolet light and visible light, That is, it is desirable to use a photocatalyst that can use many wavelengths contained in sunlight as energy), for example, a visible light responsive titanium oxide photocatalyst. As such a visible light responsive titanium oxide photocatalyst, for example, a coating agent using “Blue Active-PW25” (photocatalyst powder) or “Blue Active EX-1” (“Blue Active-PW25”) manufactured by Nobuchi Sangyo Co., Ltd. ).

  When a photocatalyst pellet, for example, a titanium oxide photocatalyst pellet, is used as the photocatalyst, the titanium oxide photocatalyst pellet is (1) baked and solidified with titanium oxide powder and (2) mixed with an inorganic adhesive such as clay. (3) A method of coating a titanium oxide photocatalyst coating solution on ceramics, metal or glass pellets, pebbles, etc., and heating to coat the surface with a titanium oxide film, (4) The surface of the titanium metal pellets It can be produced by various methods such as a method of oxidizing to a titanium oxide photocatalyst.

  In the electrode catalyst ink according to the present invention, the dispersion solvent, the catalyst powder, and the photocatalyst are blended in a predetermined amount of water (preferably pure water), and, if necessary, solid polymer electrolyte and hydrophobic binder particles. At least one of them, polyhydric alcohols such as propylene glycol, ethylene glycol and glycerin can be added.

  The solid polymer electrolyte is not particularly limited, and examples thereof include perfluorosulfonic acid type polymers such as Nafion (registered trademark).

  The hydrophobic binder particles are not particularly limited, and examples thereof include fluorine-containing compounds such as PTFE (polytetrafluoroethylene).

  Examples of the preferred composition of the electrode catalyst ink according to the present invention, for example, a preferred composition when a solid polymer electrolyte is added, include the following. This composition is indicated by the weight ratio of other components to 60% Pt-supported carbon.

Ingredient Weight ratio 60% Pt-supported carbon: 1
Pure water: 2-7
Ethanol: 3-7
10% Nafion solution: 2-8
Propylene glycol: 0-3
Photocatalyst: 0.003 to 0.01

  The electrode catalyst ink storage method of the present invention is the electrode catalyst ink storage method according to the present invention, wherein the electrode catalyst ink is stored in a transparent container, and the electrode catalyst ink stored in the transparent container. The electrode catalyst ink is irradiated with light while being stirred with a stirrer.

  The transparent container is not particularly limited as long as it can transmit light, and a transparent glass container or a transparent resin container can be used. In addition, as transparent resin containers, transparent resins such as PMMA, PC, PS, CR-39, SAN, methyl methacrylate / styrene copolymer (MAS), PVC, and poly-4-methylmentene-1 (TPX) are used. Containers can be used.

  The stirring device is not limited to melting as long as the electrode catalyst ink can be stirred. Moreover, the rotation speed at the time of stirring is not specifically limited, either, About 50-300 rpm can be set.

  The light applied to the electrode catalyst ink is not particularly limited as long as the photocatalyst of the photocatalyst body can be brought into a photoexcited state to exert a photocatalytic action, and can be irradiated with visible light or ultraviolet light depending on the type of the photocatalyst. .

It is preferable that a transparent photocatalyst coat layer is formed on the inner wall surface of the transparent container. The type of the photocatalyst in the photocatalyst coating layer is not particularly limited as long as it does not adversely affect the catalyst powder in the electrode catalyst ink as in the photocatalyst in the photocatalyst body, and titanium oxide, (TiO ₂ ), or platinum is used. Supported titanium oxide (Pt / TiO ₂ ) can be used. Of course, it is possible to use a photocatalyst that exhibits photooxidation power when irradiated with ultraviolet rays, but a photocatalyst imparted with visible light responsiveness that exhibits photooxidation power even when irradiated with visible light, such as the visible light responsive type described above. It is desirable to use a titanium oxide photocatalyst.

  This photocatalyst coating layer can be formed by applying a transparent photocatalyst coating liquid to the inner wall surface of a transparent container, drying and firing. For example, a visible light responsive titanium oxide coating agent (such as “Blue Active EX-1” manufactured by Nobori Sangyo Co., Ltd.) is applied to the inner wall surface of the transparent container, dried, and then fired at a temperature of about 400 to 600 ° C. By doing so, a photocatalyst coat layer can be formed. The thickness of the photocatalyst coat layer is not particularly limited, but can be about 200 to 500 μm.

  The method of using the electrode catalyst ink of the present invention is a method of using the electrode catalyst ink according to the present invention, wherein the electrode catalyst ink is stored in a transparent container, and the electrode catalyst ink stored in the transparent container. A storage step of irradiating the electrode catalyst ink with light while stirring with a stirrer, and supplying the electrode catalyst ink to a coating part through a pipe connected to the transparent container. This is a coating process in which the electrode catalyst ink is applied to a product.

  The storage step in the method for using the electrode catalyst ink can be the same as the method for storing the electrode catalyst ink of the present invention. In this storage step, the same as the transparent container used in the electrode catalyst ink storage method of the present invention, except that a pipe for supplying the electrode catalyst ink to the coating portion is connected near the bottom. A transparent container can be used.

  In the coating step, the electrode catalyst ink is supplied to a coating part through a pipe connected to the transparent container, and the electrode catalyst ink is applied to the object to be coated from the coating part. The pipe used at this time may be made of stainless steel, but is preferably made of transparent glass or transparent pipe made of the transparent resin. In the case of a transparent pipe, light can be irradiated to the photocatalyst body in the electrode catalyst ink that passes through the pipe, so that deterioration of the electrode catalyst ink is prevented by the photocatalytic action even while the electrode catalyst ink passes through the pipe. Can do. Moreover, when it is set as transparent piping, it is preferable that the said transparent photocatalyst coat layer is formed also in the inner wall surface of this transparent piping like the said transparent container.

  And in the usage method of the electrode catalyst ink of this invention, after removing the said photocatalyst body contained in the said electrode catalyst ink by the said coating process, this electrode catalyst ink is supplied to the said coating part. The method for removing the photocatalyst is not particularly limited. For example, a filter part capable of removing the photocatalyst can be provided in the middle of the pipe.

  In addition, when adopting a transparent pipe (the same applies when a photocatalyst coat layer is formed on the inner wall surface of the transparent pipe), among the pipes connecting the transparent container and the coating part, the transparent container is changed to the filter part. What is necessary is just to make the range until it is transparent piping. This is because it is not necessary to make the pipe transparent or form a photocatalyst coat layer after the photocatalyst is removed by the filter portion.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  In this embodiment, the present invention is applied to an electrode catalyst ink used for forming an electrode of a polymer electrolyte fuel cell.

  FIG. 1 is a cross-sectional view schematically illustrating a method for producing an electrode catalyst ink and a storage method (storage container) according to the present embodiment.

  The storage container 10 includes a transparent glass container 11 with a transparent glass lid 11 a and a stirring device 12. A transparent photocatalyst coating layer 13 having a thickness of about 300 μm is formed on the inner wall surface (bottom surface and side surface) of the transparent glass container 11 with a uniform thickness. The photocatalyst coat layer 13 is made of a transparent film-like photocatalyst made of only anatase-type titanium oxide.

  The photocatalyst coat layer 13 was formed as follows. That is, a commercially available visible light responsive titanium oxide coating agent (“Blue Active EX-1” manufactured by Nobuchi Sangyo Co., Ltd.) was first prepared. This titanium oxide coating agent uses a dispersion solution in which visible light responsive titanium oxide powder ("Blue Active PW25" manufactured by Nobori Sangyo Co., Ltd.) is dispersed in isopropyl alcohol as a solvent, using an inorganic binder. Coating agent.

  And the transparent photocatalyst coating layer 13 which consists only of anatase type titanium oxide by apply | coating the said titanium oxide coating agent to the inner wall surface of the transparent glass container 11 by uniform thickness, baking at the temperature of about 550 degreeC after drying. Was formed on the inner wall surface of the transparent glass container 11.

  On the other hand, the photocatalyst pellet 1 was prepared. The photocatalyst pellet 1 is composed of a transparent glass pellet (diameter of about 20 mm) as a base material and a transparent photocatalyst coating layer having a thickness of about 300 μm coated on the surface of the glass pellet. In addition, this photocatalyst coat layer consists of a transparent film-like photocatalyst which consists only of anatase type titanium oxide like the said photocatalyst coat layer 13 formed in the inner wall face of the transparent glass container 11. FIG.

  This photocatalyst pellet 1 was produced as follows in the same manner as the photocatalyst coat layer 13. That is, a commercially available visible light responsive type titanium oxide coating agent (“Blue Active EX-1” manufactured by Nobiki Sangyo Co., Ltd.) was applied to the surface of the glass pellet with a uniform thickness, and after drying, about 550 ° C. By baking at a temperature, a transparent photocatalyst coating layer consisting only of anatase-type titanium oxide was formed on the surface of the glass pellet.

  Using the storage container 10 and the photocatalyst pellet 1, the electrode catalyst ink 2 was manufactured as shown below, and the manufactured electrode catalyst ink 2 was stored.

  First, a catalyst powder made of 60 wt% Pt-supported carbon obtained by supporting platinum as a catalytically active substance on carbon powder as a conductive catalyst carrier was prepared. Moreover, a 10% electrolyte solution of Nafion (registered trademark) as a solid polymer electrolyte was prepared. Furthermore, pure water, ethanol and propylene glycol were prepared. Then, 60% PT-supported carbon, pure water, ethanol, 10% Nafion solution and propylene glycol as the catalyst powder were mixed and stirred, and then dispersed by a jet mill disperser to produce 3 liters of ink. This ink is black.

  The ink thus obtained was put into the glass container 11 together with about 30 photocatalyst pellets 1 to produce an electrode catalyst ink 2 according to this example.

  The composition of the obtained electrode catalyst ink 2 is as follows. This composition is indicated by the weight ratio of other components to 60% Pt-supported carbon. The weight ratio of the photocatalyst is the weight ratio of the photocatalyst coat layer in the photocatalyst pellet 1.

Ingredient Weight ratio 60% Pt-supported carbon: 1
Pure water: 5
Ethanol: 5
10% Nafion solution: 4
Propylene glycol: 2
Photocatalyst: 0.007

  Then, in a state where the transparent glass container 11 containing the electrode catalyst ink 2 is covered with the lid 11a, the storage container 10 is placed in a place where the visible light hits, and the stirring device 12 is stirred at a rotation speed of 100 rpm. Electrocatalyst ink 2 was stored. That is, while stirring the electrode catalyst ink 2 with the stirring device 12, visible light is applied to the photocatalyst coat layer 13 formed on the inner wall surface of the transparent glass container 11 and the photocatalyst coat layer of the photocatalyst pellet 1 circulating in the electrode catalyst ink 2. Irradiated. When the electrode catalyst ink 2 was stored while maintaining this state, the usable period of the electrode catalyst ink 2 was extended to two weeks.

  Thus, the deterioration of the electrode catalyst ink 2 was suppressed because the electrode catalyst ink 2 contained the photocatalyst pellet 1 as a photocatalyst and the photocatalyst coat layer 13 on the inner wall surface of the transparent glass container 11. Therefore, when these photocatalysts are irradiated with light, the photocatalysts are in a photoexcited state, exhibiting strong photooxidation power and decomposition ability, thereby suppressing the alteration of ethanol as a dispersion solvent. At the same time, it is considered that the electrocatalyst ink 2 exerted its anti-corruption, fungicidal and deodorizing effects.

  Further, in this method of storing the electrode catalyst ink, the electrode catalyst ink 2 including the photocatalyst pellet 1 is irradiated with light while being stirred by the stirring device 12, and therefore, by circulating the photocatalyst pellet 1 in the electrode catalyst ink 2, The dispersibility of the photocatalyst pellet 1 is improved, and all the photocatalyst pellets 1 can be present on the surface side of the electrode catalyst ink 2. For this reason, even if the ink is black, it is possible to irradiate all the photocatalyst pellets 1 more evenly, and the action of the photocatalyst can be exhibited more effectively. In addition, since the photocatalyst coat layer 13 is formed on the inner wall surface of the transparent glass container 11, the deterioration of the electrode catalyst ink 2 can be suppressed by the action of the photocatalyst existing in the photocatalyst coat layer 13, so that The deterioration of the electrode catalyst ink 2 can be effectively suppressed.

  Of course, the transparent glass container 11 of the storage container 10 may be used in combination as a container for ink preparation.

(Comparative example)
The electrode catalyst ink was manufactured and stored in the same manner as in Example 1 except that the photocatalyst coat layer 13 was not formed on the inner wall surface of the transparent glass container 11 and the photocatalyst pellet 1 was not added. The usable period was one week.

  FIG. 2 is a cross-sectional view schematically illustrating the method for using the electrode catalyst ink and the coating apparatus according to the present embodiment.

  The coating apparatus 20 includes a transparent glass container 21 with a transparent glass lid 21a, a stirring device 22, a pipe 23 having one end connected to a side surface near the bottom of the transparent glass container 21, and the other end of the pipe 23. The coating part 24 connected to the pipe 25, the pump 25 disposed in the middle of the pipe 23, and the filter part 26 provided in the middle of the pipe 23 closer to the coating part 24 than the pump 25. Yes.

  The piping 23 has a range from the transparent glass container 21 to the filter portion 26 made of transparent glass-made transparent piping 23a, while a range from the filter portion 26 to the coating portion 26 has a stainless steel piping 23b. .

  The filter unit 26 is made of a material (glass, ceramics, etc.) that does not affect the ink.

  A transparent photocatalyst coating layer 27 having a thickness of about 300 μm is formed on the inner wall surface (bottom surface and side surface) of the transparent glass container 21 and the inner wall surface of the transparent pipe 23a with a uniform thickness. The photocatalyst coat layer 27 is made of a transparent film-like photocatalyst made of only anatase-type titanium oxide, as with the photocatalyst coat layer 13 of Example 1, and is formed by the same method as the photocatalyst coat layer 13. It is.

  Using this coating apparatus 20, an electrode catalyst ink was applied to a substrate or a film as an object to be coated as shown below.

  First, in the same manner as in Example 1, the electrode catalyst ink 2 was produced, and the electrode catalyst ink 2 was stored in the storage container 10. Then, the electrode catalyst ink 2 is put into the transparent glass container 21 of the coating apparatus 20, and the coating apparatus 20 is installed in a place where the transparent glass container 21 is exposed to visible light with a lid 21a. Then, the pump 25 was operated while stirring the stirring device 23 at a rotation speed of 100 rpm. Thus, while preventing the electrode catalyst ink 2 from being deteriorated, the photocatalyst pellet 1 was removed from the electrode catalyst ink 2 by the filter unit 26, and the electrode catalyst ink 2 was applied from the coating unit 24 to the object to be coated.

  Therefore, even during the coating process in which the electrode catalyst ink 2 is applied to the object to be coated from the coating unit 24, the inner surface of the photocatalyst pellet 1 and the transparent glass container 11 and the transparent pipe 23a included in the electrode catalyst ink 2. The deterioration of the electrode catalyst ink 2 can be suppressed by the photocatalytic action of the photocatalyst coat layer 27 formed on the surface.

  Of course, the transparent glass container 21 of the coating apparatus 20 can be used in combination as a container for preparing ink or a container for storing the electrode catalyst ink 2.

  In the above-described embodiment, an example in which a visible light responsive titanium oxide photocatalyst is used as the photocatalyst of the photocatalyst pellet 1 and the photocatalyst coating layers 13 and 27 has been described. Of course, it is also possible to adopt. In this case, it is necessary to irradiate ultraviolet rays with an ultraviolet lamp or the like that can exhibit the photocatalytic action with the photocatalyst in a photoexcited state.

It is sectional drawing which illustrates typically the manufacturing method and storage method (storage container) of the electrode catalyst ink which concern on Example 1. FIG. It is sectional drawing which illustrates typically the usage method and coating apparatus of the electrode catalyst ink which concern on Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photocatalyst pellet (photocatalyst body) 2 ... Electrode catalyst ink 11, 21 ... Transparent glass container 12, 22 ... Stirrer 13, 27 ... Photocatalyst coat layer 23 ... Piping 23a ... Transparent piping 24 ... Coating part 26 ... Filter part

Claims (6)

An electrode catalyst ink used for forming an electrode of a fuel cell,
A dispersion solvent comprising a lower alcohol;
A catalyst powder dispersed in the dispersion solvent and carrying a catalytically active substance on a catalyst carrier;
An electrode catalyst ink comprising a photocatalyst dispersed in the dispersion solvent. For forming an electrode of a fuel cell, comprising: a dispersion solvent composed of a lower alcohol; a catalyst powder dispersed in the dispersion solvent and carrying a catalytically active substance on a catalyst carrier; and a photocatalyst dispersed in the dispersion solvent. A method of storing an electrocatalyst ink to be used,
The electrode catalyst ink is stored in a transparent container, and the electrode catalyst ink is irradiated with light while stirring the electrode catalyst ink stored in the transparent container with a stirring device. Method.   The method for storing an electrocatalyst ink according to claim 2, wherein a transparent photocatalyst coat layer is formed on the inner wall surface of the transparent container. For forming an electrode of a fuel cell, comprising: a dispersion solvent comprising a lower alcohol; a catalyst powder dispersed in the dispersion solvent and carrying a catalytically active material on a catalyst carrier; and a photocatalyst dispersed in the dispersion solvent. A method of using an electrode catalyst ink to be used,
Storing the electrode catalyst ink in a transparent container, and irradiating the electrode catalyst ink with light while stirring the electrode catalyst ink stored in the transparent container with a stirring device;
The electrode catalyst ink is supplied to a coating part through a pipe connected to the transparent container, and comprises a coating process for coating the electrode catalyst ink from the coating part to an object to be coated,
In the coating step, the electrode catalyst ink is supplied to the coating part after removing the photocatalyst contained in the electrode catalyst ink.   The method for using an electrode catalyst ink according to claim 4, wherein the pipe is a transparent pipe.   6. The method of using an electrocatalyst ink according to claim 4, wherein a transparent photocatalyst coating layer is formed on an inner wall surface of at least one of the transparent container and the transparent pipe.

Images