JP2013213275A - Electrode for electrolysis and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for electrolysis capable of obtaining high adhesion between a substrate and an electrode active material coated on a surface of the substrate while suppressing reduction in electric conductivity, and a method for producing the electrode.SOLUTION: An electrode 10 for electrolysis includes a conductive substrate 101 composed mainly of Ti, an electrode active material part 102 including platinum group metals or oxide thereof, and an adhesive force development part 103. The adhesive force development part 103 has an insulating nanofiber part 103a, in which fibers having a size of 200 nm or smaller in diameter and consisting of TiOor titanate formed on the substrate 101 are entangled. In the electrode 10 for electrolysis: the insulating nanofiber part 103a is configured to support at least a part of the electrode active material part 102; and the nanofiber part 103a has a prescribed thickness that enables the substrate and the electrode active material part 102 to be connected electrically. The method for producing the electrode 10 includes an alkali treatment process of forming the nanofiber part 103a on the surface of the substrate 101.

Description

  The present invention relates to an electrode for electrolysis used in industrial and consumer electrolysis processes involving oxygen generation or chlorine generation and a method for producing the same.

  Conventionally, electrodes made of lead or lead alloys have been used in electrolysis processes such as plating with oxygen generation, metal surface treatment, and wastewater treatment. The use of these electrodes has problems such as contamination of the plating solution by the eluted lead, electrode deterioration due to lead deposited on the anode, etc., and stable operation has not been possible. There were similar problems with electrodes used in salt electrolysis, seawater electrolysis, and water electrolysis with generation of chlorine.

  In view of such circumstances, insoluble electrodes in which an electrode active material layer is formed on a conductive band substrate have been developed and variously proposed as an alternative to lead or lead alloys. One of them is a valve metal, in particular, an electrode using titanium or an alloy containing titanium as a main component (hereinafter referred to as titanium alloy) as a conductive substrate, and an electrode active material containing a platinum group metal or an oxide thereof on the electrode. The electrode provided with the layer is widely used as an insoluble electrode in industrial electrolysis or consumer electrolysis.

With this insoluble electrode, since the electrode itself does not elute, it is possible to solve the problem of contamination like conventional lead-based electrodes and precipitation of lead on the electrodes. However, there is an essential problem that the electrode life is short due to the adhesion between the conductive substrate and the electrode active material layer.

In order to solve the problem of adhesion between the conductive substrate of the electrode and the electrode active material layer, the surface of the conductive substrate is roughened in advance. This is a method in which an anchor effect is exhibited by roughening and the electrode active material layer is firmly adhered and fixed to the surface of the conductive substrate, thereby improving the durability of the insoluble electrode. As a roughening method, it is immersed in a fluidized bath or a static bath of an acid solution such as oxalic acid, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, etc. There are a chemical etching method for dissolving the surface of the conductive substrate, an electrolytic oxidation method for electrolytically oxidizing the surface of the conductive substrate in an electrolyte solution, and making the surface of the substrate porous (Patent Document 1). A method of combining two or more of these pretreatment methods is also considered (Patent Document 2).

  The roughening measures improve the adhesion between the conductive substrate and the electrode active material layer and extend the electrode life. However, when it is applied to an electrode that is used to generate chlorine or hypochlorous acid by electrolyzing a solution containing chloride ions, or an electrode that has a large electrode load such as an electroplating electrode, the adhesion is insufficient. Left practical challenges.

  Under such circumstances, in order to realize a satisfactory electrode life even at a practical level, it is required to further improve the adhesion between the conductive substrate and the electrode active material layer. In response to this technical problem, a porous layer made of a powder sintered body of the same metal as the base is formed on the surface of the conductive base to develop a stronger anchoring effect and effectively prevent the electrode active material from falling off. A method has been considered (Patent Document 3). In another method, the surface of the conductive substrate is electrolytically oxidized under certain conditions to make the surface of the substrate a composite porous material consisting of nanometer-order micropores and micrometer-order coarse pores, making it more powerful. A method has been conceived in which an effective anchor effect is exhibited and the electrode active substance is effectively prevented from falling off (Patent Document 4).

Measures for forming a porous layer made of a powder sintered body are effective in improving the anchoring effect if the electrode active material is firmly inserted deeply, and the porous layer is connected to the conductive substrate. Since they are the same metal, there is no problem such as a decrease in conductivity. However, the porous layer made of a powder sintered body is unlikely to be open pores in which all the holes lead to the conductive substrate, and is likely to be closed pores in the middle. In this case, the electrode active substance can only enter part of the porous layer, and there is a possibility that a sufficient anchor effect may not be exhibited. Therefore, in order to achieve a sufficient anchor effect by this method, it is necessary to control the porosity in the sintered body, which is difficult to realize.

Measures to make the surface of the composite into a nanometer-order diameter and μm-order diameter by electrode oxidation treatment, a strong anchor effect is demonstrated if the electrode active substance penetrates deeply into the composite porosity. It is effective for extending the service life. However, the surface produced by electrolytic oxidation treatment is made porous by repeating the phenomenon that the surface of the conductive substrate repeats microscopic oxidation and dissolution, and a large number of fine recesses are formed on the surface. It can be said that the porous body has a complex shape in which a large number of concave portions are combined. Therefore, it is difficult to firmly enter the electrode active substance deeply into the fine and complicated hole, and the part that did not enter becomes a void, which becomes a starting point of dropping and breaking, and the anchor effect has not been sufficiently improved. .
In addition, since the electrode active material is supported in the pores of the nm order diameter and the μm order diameter, there is a limit to the amount of the electrode active material that can be supported. Therefore, in order to carry a predetermined amount of electrode active material in order to obtain desired electrode characteristics, it is necessary to form the electrode active material portion considerably thicker than the thickness of the complicated porous portion. As a result, it was difficult to ensure satisfactory adhesion in practical use.

  On the other hand, in the field of bone substitute materials, it is known that a substrate made of titanium or a titanium alloy is dipped in an alkaline solution, the surface of the substrate is refined into nanofibers, and apatite is supported on the nanofiber portion. (Patent Document 5, Non-Patent Document 1). A model has also been proposed for the formation mechanism of the nanofiber structure (Non-Patent Document 2).

JP 2009-197284 A JP-A-8-109490 JP 2006-188742 A JP 2011-202206 A JP 2000-93498 A

Journal of the Ceramic Society of Japan 105 [2] 111-116 (1997) Adv.Mater.2006,18,2807-2824

  However, although this technique has no application examples for electrolysis electrodes and is effective in bone substitute materials, it is necessary to solve further problems in order to use it for electrolysis electrodes that require electrical conductivity. The inventors have found. That is, when the substrate made of titanium or a titanium alloy is immersed in an alkaline solution, the nanofiber portion is composed of insulating titanium oxide or insulating titanate, and the electric conductivity as an electrode I found a new problem that the sexuality is impaired.

  An object of the present invention is to provide an electrode for electrolysis capable of suppressing a decrease in electrical conductivity while having high adhesion between an electrode active substance coated on a substrate surface and the substrate, and a method for producing the same.

An electrode for electrolysis according to the present invention includes a conductive substrate mainly composed of Ti, an electrode active material portion made of an electrode active material containing a platinum group metal or an oxide thereof disposed on the surface of the substrate, a substrate, An electrode for electrolysis having an adhesion developing portion for improving adhesion with an electrode active substance portion, the adhesion developing portion being formed from a nanofiber made of TiO2 or titanate formed on a substrate. The electrode active substance part is supported on at least a part of the nanofiber part, and the nanofiber part can electrically connect the substrate and the electrode active substance part. It is characterized by a possible thickness.

In the electrode for electrolysis according to the present invention described above, a nanofiber part is provided as an adhesion developing part.
In the conventional method, the micro or nano pores are regions where the electrode active material portion is supported. Therefore, the electrode active substance does not enter into the hole, and even if it enters, the amount that can be supported in the minute hole is limited, and sufficient adhesion cannot be expressed.
On the other hand, in the present invention, the support side is a nanofiber part, and the electrode active substance part is supported on the entire periphery of the fiber. Therefore, it becomes possible to carry more electrode active materials than before, and a strong anchor effect is developed by increasing the contact area with the electrode active material portion, so that the substrate and the electrode active material portion are firmly bonded. Made it possible to do.

From the viewpoint of adhesion, the greater the thickness of the nanofiber part, that is, the longer the fiber length, the greater the anchor effect can be obtained, so the adhesion between the conductive substrate and the electrode active substance part is It becomes good. On the other hand, when the nanofiber part is adopted as the adhesion developing part, the nanofiber part is made of TiO2 or titanate to show insulation, thus preventing the electrical connection between the substrate and the electrode active substance part, The new subject that the performance as an electrode fell was discovered. In other words, if the thickness of the nanofiber part is made too thick considering only the adhesion, the nanofiber part is an insulating titanium oxide or an insulating titanate, so the base and the electrode active material part There is a problem in that it is difficult to establish an electrical connection between the electrodes, and the conductivity of the electrodes is lowered and the electrodes do not function.

In contrast, the nanofiber portion is devised so that the base and the electrode active material portion can be electrically connected to each other. Therefore, it becomes possible to secure an electrical connection between the electrode active material part that has entered the nanofiber part and the Ti substrate, and suppresses the influence of resistance due to the nanofiber part, and also connects the electrode active material part and the substrate. Defects can be eliminated. Therefore, it is possible to achieve both adhesion and electrical conductivity, and to exhibit an excellent function as an electrode over a long period of time.

The thickness of the nanofiber part in the present invention is the length from the fiber root in contact with the substrate to the point farthest away from the substrate in the vertical direction when the cross section is observed with a scanning electron microscope (SEM). .

Since the surface of the substrate mainly composed of Ti is usually covered with a very thin oxide film of about several nm, strictly speaking, the substrate and the electrode active material part are in contact with each other through the oxide film. However, a very thin film such as an oxide film does not affect the electrical connection between the electrode active material portion and the substrate. That is, in the present invention, as long as the electrical connection is not affected, the substrate and the electrode active material portion may be in contact with each other through an oxide film, for example, and the substrate and the electrode active material portion are not necessarily physically connected. It may not be in contact with.

In the electrode for electrolysis according to the present invention, the thickness of the nanofiber portion is preferably 10 nm or more and 10 μm or less.

When the thickness of the nanofiber portion is less than 10 nm, it is difficult to obtain a sufficient anchor effect, and sufficient adhesion between the substrate and the electrode active material portion cannot be expressed. On the other hand, if the thickness of the nanofiber part is excessively increased, stress concentration at the base of the nanofiber part increases, and the nanofiber part may be peeled off from the base. Moreover, when the nanofiber part falls down without peeling, the ratio of the nanofiber part in the thickness space of the nanofiber part increases, and the space in which the electrode active substance part can be supported decreases. Therefore, poor support of the electrode active substance part to the nanofiber part may occur, and the adhesion may be reduced, or electrical connection may not be ensured. Furthermore, even when the nanofiber part grows long without falling down, the conductivity is lowered because the nanofiber part is insulative. In addition, if the nanofiber part is extended for a long time, it becomes difficult for the electrode active substance part to penetrate to the base, and the electrode active substance part is poorly supported on the nanofiber part, and it is not possible to ensure electrical connection. There is a fear. The upper limit of the thickness of the nanofiber part is not particularly limited as long as the base and the electrode active substance part can be electrically connected to each other. However, for the above reason, it is preferably about 10 μm or less.
Therefore, by making the thickness of the nanofiber part in the range of 10 nm or more and 10 μm or less, the nanofiber part is prevented from being peeled off from the base material, and excellent adhesion and electrical conductivity between the substrate and the electrode active substance part are achieved. It becomes possible to balance with securing.

In addition, for example, in the case of an electrode used for the purpose of electrolyzing a solution containing chloride ions to generate chlorine and generating sterilized water of the chlorine and water hypochlorous acid, from the viewpoint of the voltage conditions that can be applied, The thickness of the nanofiber part is preferably in the range of 10 nm to 5 μm.

In the electrode for electrolysis according to the present invention, the nanofiber preferably has a diameter of 200 nm or less.

  By making the diameter of the nanofibers 200 nm or less, the contact area between the nanofiber part and the electrode active substance part per unit area of the substrate can be sufficiently secured, and a strong anchor effect is expressed, It is possible to firmly bond the electrode active material part.

In the electrode for electrolysis according to the present invention, the electrolytically active substance preferably includes fine particles of a platinum group metal or an oxide thereof, and the particle size of the fine particles is preferably smaller than the fiber interval of the nanofiber portion.

By making the particle diameter of the platinum group metal or oxide fine particles of the electroactive substance smaller than the fiber spacing of the nanofiber part, the electroactive substance can be more reliably supported between the fibers. Therefore, it is possible to ensure a sufficient carrying amount more reliably, and it is possible to further suppress the occurrence of poor electrical bonding between the base material and the electrode active material part.

In the electrode for electrolysis according to the present invention, it is also preferable that a protective layer is formed between the nanofiber portion and the electrode active material portion. By doing so, even when the electrode active material is peeled off due to long-term use or the like, the substrate and the electrolytic solution do not come into contact with each other, so that the substrate is not damaged by voltage application. In addition, the adhesion between the nanofiber part and the protective layer is higher than the conventional one because of the large contact area, and can be firmly joined. The protective layer should be familiar with the electrode active material part and should not inhibit the electrical conductivity between the substrate and the electrode active material part.

In the electrode for electrolysis according to the present invention, the substrate surface has a rough surface portion having a specific surface area increased by a blast treatment method, a chemical etching method using an acid solution, an electrolytic oxidation treatment method, etc. It is also preferable to form the fiber portion on the rough surface portion.

  The rough surface portion is obtained by changing the structure of the surface of the Ti substrate, and it is sufficient that the specific surface area is increased as compared with that before the treatment. By forming a rough surface portion on the surface of the base material and forming a nanofiber portion thereon, it is possible to increase the amount of formation of the nanofiber portion and to develop a stronger anchor effect. Moreover, since the anchor effect of the rough surface portion itself can be expected, the adhesion force between the substrate and the electrode active material portion can be further strengthened.

Since the nanofiber portion is insulative, the main electrical connection between the electrode active material portion and the substrate is ensured in the region where the nanofiber portion is not formed on the substrate surface. Therefore, if the rough surface portion is formed on the surface of the substrate to increase the specific surface area, the number of electrical connection points between the electrode active material portion and the substrate can be increased. For this reason, it is possible to more effectively suppress a decrease in electrical conductivity between the electrode active material portion and the substrate.

In the electrode for electrolysis according to the present invention, the thickness of the nanofiber portion formed on the rough surface portion is smaller than the thickness of the nanofiber portion when the nanofiber portion is formed directly without forming the rough surface portion on the surface. It is also preferable to do.

By forming the rough surface portion on the substrate surface, the adhesion is improved by increasing the amount of nanofibers and forming the rough surface portion. That is, even if the thickness of the nanofiber portion is smaller than the thickness when the rough surface portion is not formed, it is possible to ensure sufficient adhesion. Therefore, it is possible to reduce the thickness of the nanofiber portion while maintaining the adhesive force, and it is possible to further suppress a decrease in electrical conductivity between the electrode active material portion and the substrate.

The electrode for electrolysis according to the present invention is also preferably used for an electrode for electrolysis used for a current density of 100 A / m 2 or more.

In general, when the current density of the electrode is increased, the electrode active substance is easily peeled and dissolved, and the life of the electrode for electrolysis is shortened. Accordingly, it can be said that use in a situation where the current density is high is a severe use situation for the electrode for electrolysis. However, in the electrode for electrolysis according to the present invention, even in applications where a current density of 100 A / m 2 or more is used, the base and the electrode active substance are firmly adhered, so that peeling and dissolution hardly occur, and an excellent function is provided for a long time. It is possible to demonstrate over the range.

  Examples of the electrode for electrolysis for use at a high current density of 100 A / m 2 or more include an electrode for electrolyzing a solution containing chloride ions. In this case, chlorine is generated at the anode, and the chlorine It can be used for the purpose of producing sterilized water of hypochlorous acid by the reaction of water with water. Moreover, the electrode for electrolyzing water is mentioned, In this case, it can be used for the use which produces | generates ozone water by generating ozone at an anode and melt | dissolving this ozone in water.

The electrode for electrolysis according to the present invention is also preferably used for an electrode for electrolysis in an electrolysis process accompanied by an anode cathodic phenomenon or an electrode for electrolysis in which the polarity of the electrode is periodically switched.

It has been found that even when an electrode for electrolysis having high durability is used only as an anode, in an electrolysis process involving the cathodic phenomenon of the anode, consumption at a portion where cathodicization occurs rapidly proceeds. Taking the electroplating line of steel plate as an example, the cathodic phenomenon of the anode will be described.

In an electroplating line for steel plates, two anodes are arranged opposite to each other in order to plate both surfaces of the steel plate, and a plated metal is deposited on both surfaces of the steel strip by passing a steel strip serving as a cathode between them. Here, the width of the two anodes arranged opposite to each other is set in accordance with the maximum width of the steel strip because there are various types of steel strips that pass between them. For this reason, when a steel strip having a width smaller than the maximum width passes, the electrodes are directly opposed at the side end portions on both sides of the anode. When metal plating with different thicknesses is applied to both surfaces of the steel strip, a potential difference is generated between the two anodes. In the anode on the low potential side, the side end portion where the electrodes directly face each other is a cathode. And the cathode current flows. This is the cathodic phenomenon of the anode.

Further, when the positive and negative polarities of the electrodes are periodically switched to prevent the deposits on the electrodes, the cathodes are intentionally generated, so that the consumption proceeds more rapidly.
Since the electrode for electrolysis according to the present invention has high adhesiveness and excellent electrical conductivity even in such a severe use situation, it is possible to exhibit an excellent function for a long period of time.

In the electrode for electrolysis concerning this invention, it is also preferable to utilize for the electrode for electrolysis of the use which electrolyzes the solution containing a chloride ion and generates chlorine or hypochlorous acid.

When a solution containing chloride ions containing 28.2 × 10 ⁻⁹ mol / L or more and 20 mol / L or less of chloride ions is electrolyzed, chlorine is generated. Chlorine is very reactive and is known to react with many metals and organics to form chlorides. When calcium ions or magnesium ions are contained in the solution, it is necessary to periodically change the polarity of the electrode in order to prevent the precipitation of calcium or magnesium on the electrode.
In the electrode for electrolysis according to the present invention, even if the generated chlorine touches the interface between the electrode active substance part and the nanofiber part, it has strong adhesion and high chemical stability, and thus exhibits excellent functions over a long period of time. It becomes possible. Moreover, since the adhesive force is also good, it can show high resistance against the cathodic phenomenon.

The electrode for electrolysis according to the present invention is also preferably used under high voltage conditions in an electrode for electrolysis used to generate chlorine or hypochlorous acid by electrolyzing a solution containing chloride ions.

In an application where a solution containing chloride ions is electrolyzed to generate chlorine or dichloric acid, 28.2 × 10 ^{−9 of} chloride ions such as tap water or dilute saline obtained by adding salt to tap water is used. In the case of a dilute solution containing only mol / L or more and 14.1 × 10 ⁻³ mol / L or less, since the electric conductivity is not high, a high voltage of 10 V or more and less than 50 V is applied to the electrode to cause an electrochemical reaction. Need to hang. In addition, when it is necessary to reduce the size of the electrode for electrolysis while ensuring the same amount of electrochemical reaction, it is used at a high current density.
Such a high voltage and high current density promote the desorption / peeling / dissolution of the electrode active substance, which is a severe use situation for the electrode for electrolysis, and the electrical load on the electrode for electrolysis increases. In the electrode for electrolysis according to the present invention, it is possible to develop an excellent function as an electrode over a long period of time due to high adhesion even under such severe usage conditions.

  The method for producing an electrode for electrolysis according to the present invention includes an electrode for electrolysis comprising a conductive base mainly composed of Ti and an electrode active material portion containing a platinum group metal or an oxide thereof disposed on the surface of the base. And a step of forming an insulating nanofiber portion made of nanofibers having a diameter of nanosize made of TiO2 or titanate, and an electrode active material portion in the nanofiber portion. A step of forming at least a part of the nanofiber portion, and in the step of forming the nanofiber portion, the nanofiber portion has a thickness capable of electrically connecting the substrate and the electrode active material portion. It is characterized by.

In the method for producing an electrode for electrolysis according to the present invention described above, a nanofiber portion that exhibits a strong anchor effect can be formed between the substrate and the electrode active material portion by a simple method called alkali treatment.
The nanofiber part can be expected to have a stronger anchor effect as the fiber length is longer. However, since the nanofiber part is made of insulating TiO2 or titanate, if it is too long, the substrate and the electrode active material part It becomes difficult to make an electrical connection to the electrode, and the electrical conductivity of the electrode is lowered, so that it does not function as an electrode. Therefore, the nanofiber part can be electrically contacted by direct contact between the substrate and the electrode active substance part by devising the alkali treatment conditions such as the concentration of the alkali solution, the temperature of the alkali solution, and the immersion time. It is devised to become the thickness of. Therefore, it is possible to achieve both ensuring of adhesion and suppression of decrease in electrical conductivity by a simple method.

In the method for producing an electrode for electrolysis according to the present invention, it is also preferable that the supported electrode active material part is an oxide of a platinum group metal.

When the base mainly composed of Ti is alkali-treated, an insulating nanofiber portion is formed, and the portion of the base surface where the nanofiber portion is not formed does not affect the electrical conductivity. A very thin oxide film is formed. The portion where the oxide film is formed is at the base of the nanofiber part, and in order to ensure electrical connection between the electrode active substance part and the substrate, the oxide film is formed via the nanofiber part. It is necessary to sufficiently permeate the electrode active material part up to the formed part.
Therefore, by making the electrode active substance part an oxide of a platinum group metal, the affinity with the nanofiber part and the oxide film formed at the base of the nanofiber part is improved. Easy to penetrate. Therefore, it becomes possible to ensure the electrical connection between the electrode active material portion and the substrate more reliably. Moreover, since it is oxides, adhesiveness also becomes favorable.

  In the method for producing an electrode for electrolysis according to the present invention, a rough surface portion is formed on a substrate surface by a blast treatment method, a chemical etching method using an acid solution, an electrolytic oxidation treatment method, etc., and the specific surface area is increased as compared with that before the treatment. It is also preferable to further include a step of forming a nanofiber portion after the step of further including a step and increasing the specific surface area.

  Before the step of forming the nanofiber portion, a step of forming a rough surface portion by a blast treatment method, a chemical etching treatment method using an acid solution, an electrolytic oxidation treatment method, etc. to increase the specific surface area before the treatment is performed. In this way, it is possible to increase the amount of nanofibers to be formed, and furthermore, it is possible to express a stronger adhesion between the substrate and the electrode active material part due to the anchor effect of the rough surface part itself. . In addition, since the number of electrical connection points between the substrate and the electrode active material portion is increased, it is possible to more effectively suppress a decrease in electrical conductivity between the electrode active material portion and the substrate.

  In the method for producing an electrode for electrolysis according to the present invention, in the step of forming the electrode active material part on the adhesion developing layer, the electrode active material part may be formed using a monomer or oligomer solution containing metal ions as a starting material. preferable.

  Since the adhesion developing portion has a fine structure of nanofibers, if the size of the starting material of the electrode active substance is too large, it is difficult to enter the nanofiber portion and a sufficient anchor effect cannot be obtained. Therefore, by making the starting material of the electrode active substance into a monomer or oligomer solution containing metal ions, it is possible to enter the fine nanofiber part and to exhibit a sufficient anchor effect.

In the method for producing an electrode for electrolysis according to the present invention, the monomer or oligomer solution is preferably an aqueous solution containing water as a solvent.

Since the nanofiber part according to the present invention is formed by alkali treatment, it has a feature that the hydroxyl density of the nanofiber surface is high. Therefore, by making the monomer or oligomer solution for forming the electrode active substance part into an aqueous solution, the affinity between the nanofiber part and the electrode active substance part, that is, the familiarity is improved, and the electrode activity is further increased to the back of the nanofiber part. The substance part 102 can be made to enter more reliably.

  INDUSTRIAL APPLICABILITY The present invention can provide an electrode for electrolysis that can suppress a decrease in electrical conductivity while having high adhesion between an electrode active material coated on the surface of the substrate and the substrate, and a method for producing the same.

It is a schematic diagram which shows the cross-section of the electrode for electrolysis of 1st Embodiment concerning this invention. It is a schematic diagram which shows the cross-section of the electrode for electrolysis of 2nd Embodiment concerning this invention. 3 is a scanning electron micrograph of a nanofiber portion on a substrate surface according to the present invention. It is the scanning electron micrograph of the base-material surface by the conventional oxalic acid solution process. It is a scanning electron micrograph of the cross section of the nanofiber part of the base | substrate by a reference example. It is a graph which shows the relationship between the thickness of a nanofiber part and resistance value in an Example and a comparative example. It is the electrode surface photograph after the electrolysis time 1.7 hours in the durability test of an Example and a comparative example. It is a graph which shows the relationship between the load of the electrode active material and durable electrolysis in an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same components in the drawings are denoted by the same reference numerals as much as possible, and redundant description will be omitted.

(First embodiment)
A first embodiment of the electrode for electrolysis of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a cross-sectional structure of an electrode for electrolysis according to the first embodiment of the present invention.
As shown in FIG. 1, the electrode for electrolysis 10 includes a base 101, an electrode active material portion 102, and an adhesion force expressing portion 103, and the base 101 and the electrode active material 102 are electrically connected.

The substrate 101 is a conductive material made of titanium or a titanium alloy, and the shape is processed into a shape corresponding to the electrode for electrolysis to be used.
The outermost surface of the base 101 made of titanium or a titanium alloy is usually covered with an oxide film, but its thickness is so thin that the electrical connection between the base 101 and the electrode active material portion 102 is obstructed. is not.

The electrode active material portion 102 is made of an electrode active material containing a platinum group metal or an oxide thereof. When the electrode is used for oxygen generation, the platinum group metal or an oxide thereof and a valve metal (titanium, tantalum, niobium). , Tungsten, zirconium) and mixed oxides with one or more metal oxides selected from the group consisting of tin are preferred. Representative examples include iridium-tantalum mixed oxide, iridium-tantalum-titanium mixed oxide, and the like.
When the electrode is used for generating chlorine, it is selected from the group consisting of platinum group metals such as iridium, ruthenium, platinum, palladium, rhodium or oxides thereof and valve metals (titanium, tantalum, niobium, tungsten, zirconium) and tin. Mixed oxides with one or more metal oxides are preferred. Typical examples include iridium-platinum-tantalum mixed oxide, iridium-platinum-rhodium-tantalum mixed oxide, and the like. Platinum and iridium oxides can also be used.

The crystalline state of the electrode active material may be either amorphous or crystalline.

Since the outermost surface of the base 101 is usually covered with an oxide film that is thin enough to conduct electricity, when the electrode active material contains an oxide of a platinum group metal, the oxides are familiar to each other. The electrode active material portion 102 is easily formed along the surface of the surface 101. Moreover, since it is an oxide, chemical adhesive force becomes strong.

  Moreover, since the material which comprises the nanofiber part 103a is also an oxide, when the electrode active substance part 102 contains the oxide of a platinum group metal, since it is oxides, it is familiar and it is an electrode along the nanofiber part 103a. The active material portion 102 is easily formed. Therefore, even if the nanofiber part is insulative, it is possible to secure an electrical path from the base 101 along the nanofiber part 103a. Further, since the oxides are used, the chemical adhesion between the electrode active material portion 102 and the nanofiber portion 103a can be strengthened.

Next, the adhesion developing unit 103 will be described.
The adhesion developing portion 103 has an insulating nanofiber portion 103a.
In the present invention, the nanofiber portion 103a is made of nanofiber made of TiO2 or titanate. Here, the nanofibers preferably have a diameter of 5 nm to 200 nm. Further, considering the contact area with the electrode active substance and the heat treatment conditions when producing the nanofiber part, the diameter is more preferably 5 nm or more and 15 nm or less. In addition, let the value of the diameter said here be a value at the time of observing with a transmission electron microscope (TEM).

  Note that the nanofiber portion 103a can have any structure of a tube shape having a hollow structure or a wire shape having a solid structure depending on manufacturing conditions such as a heat treatment temperature and an alkali concentration. In general, the tube shape tends to have a smaller fiber diameter than the wire shape, and it is possible to carry the electrode active substance part in the tube, so the tube shape with a hollow structure is more preferably used. Is possible.

The thickness d1 of the nanofiber portion 103a is the length from the fiber root in contact with the substrate to the point farthest from the substrate in the vertical direction when the cross section is observed with a scanning electron microscope (SEM). 10 nm or more and 10 μm or less are preferable. The thicker the thickness, the larger the contact area with the electrode active material portion 102, so that a strong anchor effect is exhibited and the base 101 and the electrode active material portion 102 can be strongly adhered. On the other hand, if the thickness is too thick, the nanofiber portion 103a is insulative, so that it is difficult to electrically connect the base 101 and the electrode active material portion 102, and electric energy is transferred to the electrode active material portion 102. It cannot be transmitted sufficiently and electrode activity is reduced. Accordingly, the thickness d1 of the nanofiber portion 103a is preferably set to a predetermined thickness that allows the anchor effect to work and allows electric energy to reach the electrode active material.
Further, if the length of the fiber becomes too long, stress concentrates on the fiber base, and there is a possibility that the fiber will peel off from the fiber base. Therefore, the range of 10 nm or more and 10 μm or less is preferable.
The predetermined thickness can be appropriately selected in consideration of the voltage condition according to the use of the electrode for electrolysis within a range where the fiber does not peel off.

The surface of the substrate 101 made of titanium or a titanium alloy when used as an electrode for electrolysis is preferably completely covered with the electrode active material portion 102. In this case, the surface of the substrate 101 is in direct contact with the electrolytic solution. There is nothing. However, there may be a case where a part of the electrode active material part 102 is peeled off from the nanofiber part 103a and a part of the substrate 101 is exposed to be in direct contact with the electrolytic solution after being used for a long time. . If a voltage is applied with the surface of the substrate 101 partially exposed, the substrate will be severely damaged.
In order to prevent this state, there is a case in which a protective layer is formed on the surface of the nanofiber portion 103a formed on the surface of the substrate 101, and an electrode active material is supported thereon to form the electrode active material portion 102. . It is preferable that the protective layer is made of a material that is easily compatible with both the base 101 and the electrode active substance portion 102 because the function of improving the adhesion between the base 101 and the electrode active substance portion 102 can be expressed. As the protective layer, a metal containing metal tantalum or a metal tantalum alloy, or a composite oxide of tantalum oxide or tantalum oxide can be considered.
In forming the protective layer, it is necessary that the electrical conductivity between the substrate 101 and the electrode active material portion 102 is not impaired. For example, when it is made of a material having electrical conductivity or is made of an electrically insulating material, it should be formed thin enough so as not to impair the electrical conductivity between the base 101 and the electrode active material portion 102. That's fine.

  Since the nanofiber portion 103a is composed of nanofibers having a diameter of 200 nm or less, there are many gaps between the nanofibers, and the electrode active material enters more than the conventional porous body structure formed by an electrolytic oxidation method or the like. Since the amount of the electrode active material that can be easily supported is large, it is possible to dilute the influence of the electrical insulation of the nanofiber portion 103a.

Further, if the electrode active material portion 102 is made of an electrode active material containing fine particles of a platinum group metal or its oxide, and the particle size of the fine particles is made smaller than the nanofiber interval, the electrode active material portion 102 becomes a nanofiber. It is possible to easily enter the gap between them, and it is possible to securely carry the nanofiber portion 103a to the base, that is, the base 101 side. Therefore, the base material 101 and the electrode active material part 102 can be electrically connected more reliably.
Moreover, it is preferable that the viscosity of the precursor of the electrode active material portion 102 is appropriately adjusted within a range in which the precursor easily enters between fibers and does not drip.

Further, the nanofiber portion 103a according to the present invention is characterized by a high hydroxyl group density on the nanofiber surface. Therefore, by making the solution for forming the electrode active material part 102 into an aqueous solution, the familiarity between the nanofiber part 103a and the electrode active material part 102 is improved, and the electrode active material part 102 is deeply inserted into the nanofiber part 103a. Can be made easier to enter.

(Second Embodiment)
A second embodiment of the electrode for electrolysis of the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing a cross-sectional structure of the electrode for electrolysis according to the second embodiment of the present invention.
As shown in FIG. 2, in the second embodiment, the adhesion developing portion 103 includes a nanofiber portion 103a and a rough surface portion 103b, and is the same as the first embodiment except that the rough surface portion 103b is provided. is there.

  The rough surface portion 103b is obtained by changing the structure of the substrate surface by treating the surface of the substrate 101 with a blast treatment method, a chemical etching method with an acid solution, an electrolytic oxidation treatment method, or the like. The specific surface area of the surface of the substrate 101 is increased. The nanofiber portion 103a is formed on the rough surface portion 103b.

Since the specific surface area of the surface of the substrate 101 is increased by forming the rough surface portion 103b, it is possible to increase the amount of the nanofiber portion 103a formed on the rough surface portion 103b. Therefore, it is possible to obtain a larger anchor effect.
In addition, by combining the rough surface portion 103b and the nanofiber portion 103a, not only the anchor effect by the nanofiber portion 103a but also the anchor effect of the rough surface portion 103b itself can be added to express a stronger anchor effect. As a result, the substrate 101 and the electrode active material portion 102 can be bonded more firmly.

Moreover, the area | region where the nanofiber part 103a on the surface of the base | substrate 101 which has contributed to ensuring of electrical conductivity between the base | substrate 101 and the electrode active material part 102 is not formed by the specific surface area of the base | substrate 101 surface increasing increases. Therefore, the electrical conductivity between the substrate 101 and the nanofiber portion 103a can be ensured more reliably.

  If the structure of the adhesion developing portion 103 is devised to include the nanofiber portion 103a and the rough surface portion 103b, an adhesion force equivalent to the adhesion force obtained by the thickness d1 of the nanofiber portion when the rough surface portion 103b is not provided is expressed. The thickness d2 of the nanofiber portion 103a for making it possible to make it smaller than d1. If the thickness d2 of the insulative nanofiber portion 103a is reduced, the base 101 and the electrode active material portion 102 are easily electrically connected, and the electric energy can be efficiently used for the electrolytic chemical reaction. Thus, it is possible to achieve both of ensuring adhesion and ensuring electrical conductivity more reliably.

(Method for producing electrode for electrolysis)
Details of the method for manufacturing the electrode 10 for electrolysis according to the present invention will be described below.

  In the method for manufacturing the electrode 10 for electrolysis according to the present invention, first, a conductive substrate 101 made of titanium or a titanium alloy is prepared. The shape of the conductive substrate 101 may be processed into a shape corresponding to the electrode 10 for electrolysis to be manufactured, or may be a plate shape before being processed.

Next, the base 101 is degreased and then subjected to an alkali treatment in which it is immersed in an alkaline solution. Before the alkali treatment, the substrate is immersed in a fluidized or static bath of an acid solution such as oxalic acid, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, or a blasting method in which abrasives are sprayed to roughen the surface mechanically. The surface of the base 101 is electrolytically oxidized in an electrolyte solution, and the surface of the base 101 is electrolytically oxidized to make the surface porous. The specific surface area of 101 may be increased.

The alkali solution used for the alkali treatment is not particularly limited as long as it has basicity. However, since it is easily available and water-soluble and easy to handle, a single solution or a mixture of a strong base compound such as sodium hydroxide or potassium hydroxide is used. It is preferable to use a solution. The concentration may be 0.01 mol / L or more, and preferably 5 mol / L or more, the nanofiber portion 103 can be suitably formed.

The alkali solution temperature during the alkali treatment may be in the range of 20 ° C to 250 ° C. It is known that when the temperature is increased, the nanofiber portion 103a is not a tube shape having a small diameter and a hollow structure, but a wire shape having a larger diameter and a solid structure. Therefore, in consideration of the contact area with the electrode active material portion 102 and the heat treatment conditions in production, a range of 40 ° C. to 180 ° C. in which a tube shape can be preferably used can be suitably used.

  Although the immersion time of the alkali treatment varies depending on the alkali concentration and temperature of the solution, it is generally 1 minute or more, and preferably 1 hour or more and less than 100 hours. Since the thickness of the nanofiber portion 103a is determined by this immersion time, the substrate 101 and the electrode activity are determined according to the required life, voltage conditions, or the properties of the electrode active material portion 102 for each application of the electrode 10 for electrolysis to be used. The time can be adjusted within a range in which conductivity with the substance portion 102 can be ensured.

By this alkali treatment, it is possible to form the nanofiber portion 103a that is extremely effective for exerting the anchor effect on the surface of the conductive substrate 101 made of titanium or a titanium alloy.

Next, the formation mechanism of the nanofiber part 103a will be described. In addition, although the formation mechanism of a nanofiber part is not certain, it thinks as follows. However, the following explanation is only a hypothesis, and the present invention is not limited by this.
First, titanium on the surface of the substrate 101 is dissolved by the alkaline solution, but is precipitated again because of the high concentration of titanium ions in the vicinity of the surface. This reprecipitation has anisotropy in the growth direction, and nanofibers extending in one direction are formed by repeating dissolution-reprecipitation. Since this nanofiber is formed at various locations on the surface of the substrate, it can be considered that the nanofiber portion 103a is intertwined in a complicated manner.

Since the nanofiber portion 103a is formed by the dissolution-reprecipitation mechanism, the concentration balance of titanium ions in the vicinity of the surface of the substrate 101 is important. Therefore, if factors such as the alkali solution concentration and the alkali treatment temperature are controlled to change the titanium ion concentration in the vicinity of the surface of the substrate 101, the nanofiber portion 103a is not formed or the time required for the formation varies.

After the alkali treatment, the substrate 101 is taken out and washed with water. You may wash | clean with an acidic solution in order to remove cations, such as sodium. Furthermore, since the surface of the base 101 after the alkali treatment is titanic acid containing protons, sodium, etc., it can be heat treated to be TiO 2 or titanate.

Next, a process of supporting the electrode active material portion 102 on the nanofiber portion 103a formed on the surface of the substrate 101 will be described.
As a method for forming the electrode active material portion 102 on the surface of the substrate 101, a pyrolytic sintering method, an electroplating method, or the like can be applied. However, the pyrolytic sintering method is preferable because of technical difficulty and cost.

  The electrode active material is preferably a monomer or oligomer solution containing a metal ion as a starting material. This is because the nanofiber portion 103a, which is the adhesion developing portion 103, has a fine structure of nanofibers, so if the size of the starting material of the electrode active material is too large, it is difficult to enter the nanofiber portion, and a sufficient anchor effect It is because it becomes impossible to obtain. When colloid is used as the starting material, it is preferable to make the colloid particles smaller than the interval between the nanofiber portions for the same reason. In addition, the space | interval of a nanofiber part is a distance of one nanofiber and another nanofiber in the closest position of the fiber, and is about several nm-200 nm.

  Also, by using a monomer or oligomer solution containing metal ions as an aqueous solution, it is possible to improve the familiarity with the nanofiber part 103a containing a large amount of hydroxyl groups, and to make it easier for the electrode active substance to enter between the nanofibers. preferable.

The method of applying a solution containing an electrode active material to the surface of the substrate 101 is a variety of existing methods, for example, flow coating, spin coating, tape molding, as long as the electrical connection between the substrate 101 and the electrode active material portion 102 can be obtained. , Screen printing, brush coating, and the like can be used.

In addition, a protective layer such as tantalum may be formed on the surface of the nanofiber portion 103a, and an electrode active material may be supported to form the electrode active material portion 102.

  After application of the solution, the electrode active material portion 102 is dried to fix the electrode active material portion 102 to the substrate 101, and heat treatment is performed at a temperature of 300 ° C. to 800 ° C. in order to crystallize the electrode active material portion 102. The temperature of the heat treatment needs to be a temperature at which the target electrode active material portion 102 is formed. However, if the temperature is too high, the thickness of the oxide film formed on the surface of the base 101 increases, and the base There is a possibility that electrical conductivity between the electrode 101 and the electrode active material portion 102 may be hindered. Therefore, it is preferable to select appropriately within a range in which the electrical conductivity between the base 101 and the electrode active material portion 102 is not hindered.

The coating, drying, and baking steps are repeated several to several tens of times, and the target amount of the electrode active material is supported on the surface of the substrate 101.

  As described above, according to the present invention, the electrode 10 for electrolysis capable of securing a strong adhesion force by the nanofiber portion 103a without impairing the electrical connection between the base 101 and the electrode active material portion 102 and the production thereof. A method can be provided. Therefore, it can be particularly suitably used for applications that require stronger adhesion between the substrate 101 and the electrode active material portion 102.

For example, in use under a current density of 100 A / m2 or more, use in an electrolytic process involving the cathodic phenomenon of an anode, such as a steel plate electroplating line, and use in applications that generate chlorine or hypochlorous acid. Further, it is possible to effectively prevent the electrode active material portion 102 from being detached from the base 101 without deteriorating the function as an electrode, and the life of the electrode can be prolonged as compared with the conventional case.

The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

(Example)
As the conductive substrate, a JIS type 1 titanium plate (thickness: 0.5 mm) pressed into a shape of 20 mm × 40 mm was prepared. This was immersed in acetone, ultrasonically cleaned for 10 minutes, degreased, and then immersed in a 5 mol / L sodium hydroxide aqueous solution under the temperature and time conditions of the substrate processing method shown in Table 1 to perform alkali treatment of the substrate. It was. Samples 1 to 6 of the reference example were completed at this point without applying the electrode active material.

Next, a butanol solution of chloroiridium acid adjusted to an iridium concentration of 100 g / L, a butanol solution of tantalum ethoxide adjusted to a tantalum concentration of 100 g / L, and a butanol solution of chloroplatinic acid adjusted to a platinum concentration of 200 g / L, The rhodium chloride butanol solution adjusted to a rhodium concentration of 100 g / L was weighed so that the metal conversion composition ratio of Ir—Ta—Pt—Rh was the mol% shown in Table 1, and the total metal conversion concentration was As shown in Table 1, it was diluted with butanol to prepare a coating solution.

Each solution was weighed with a pipette in the amount shown in Table 1, applied to the nanofiber part formed on the titanium substrate, dried at room temperature, and further baked in the air at 550 ° C. for 10 minutes. This application / drying / firing was repeated as many times as shown in Table 1 to prepare Example Samples 1 to 10 of the electrode for electrolysis.

(Comparative example)
As a comparative example, as shown in Table 1, the substrate treatment of the above example was not performed, or a treatment of immersing in a 10 wt% oxalic acid solution at 90 ° C. for 1 hour was performed. Samples 1 to 5 of comparative examples were produced in the same manner.

(Evaluation)
The sample samples 1 to 10 and the comparative example sample 1 of the produced electrode were applied with a potential using a potentiostat (Hz-5000, manufactured by Hokuto Denko Co., Ltd.), the current value was measured, and the resistance was measured. The value was determined. The measurement uses a 1 M sodium sulfate solution (liquid temperature 27 ° C., pH 6.5) as the electrolyte, an Ag-AgCl electrode as the reference electrode, and a Pt electrode as the counter electrode, a distance between the electrodes of 0.5 mm, and a natural potential of 5 mV / s. The potential was increased to 2 V at a speed of 1 mm and the current value was measured. The resistance value was obtained from the value of the potential at a point where current flows 0.4 A.

  The endurance test as a hypochlorous acid generation electrode was implemented with respect to the Example electrode 7-10 of the produced electrode for electrolysis, and the comparative example samples 2-5. In the durability test, tap water with a flow rate of 0.45 L / min was used as the electrolyte, the distance between the electrodes was 0.5 mm, the current density was 1470 A / m 2 (current 1 A, electrode area 680 mm 2), and the electrolysis time was every 5 seconds. The anode and the cathode were reversed, and the electrolysis cycle was repeated for 5 seconds by electrolysis for 1 second. The time course of the electrolysis voltage value and free chlorine concentration was recorded, and the time when the free chlorine concentration generated by the electrode for electrolysis fell below 0.3 ppm was defined as the life. The free chlorine concentration was measured using a pocket residual chlorine system (model number: HACH2470, reagent used: for DPD (diethyl-p-phenylenediamine) 10 ml).

FIG. 3 shows a scanning electron microscope (SEM) photograph of the surface of the Ti substrate of Sample 1 after the alkali treatment. Moreover, in FIG. 4, the SEM photograph after a process by an oxalic acid solution is shown as a comparative example. From FIG. 3, it can be confirmed that the surface of the Ti substrate has a nanofiber structure in which nanowires are intertwined. On the other hand, as shown in FIG. 4, in the treatment with the oxalic acid solution, the surface of the substrate is formed with unevenness on the micro order level.

The scanning electron microscope (SEM) photograph of the cross section of the nanofiber part of Ti base | substrate of the reference example samples 1-6 is shown in FIG. From (a)-(c), it can confirm that the thickness of a nanofiber part is so thick that immersion time becomes long. Moreover, from the comparison of (a) to (c) and (d) to (f), when the immersion time is the same, it can be confirmed that the higher the solution temperature is, the thicker the nanofiber portion is. .

Table 1 shows the result of the resistance value by the potentiostat. When the temperature of the alkaline solution is the same in the substrate treatment, the resistance value increases as the immersion time increases. Further, when the immersion time is the same, the resistance value is higher when the temperature of the alkaline solution is 100 ° C. than when the temperature is 60 ° C. Moreover, in FIG. 6, the relationship between the thickness of the fiber part of Examples 1-16 and the comparative example sample 1 and resistance value is shown. The horizontal axis indicates the thickness of the fiber portion confirmed by the scanning electron microscope (SEM) under the same substrate processing conditions, and the vertical axis indicates the resistance value. This shows that the resistance value increases as the thickness of the fiber portion increases.

Table 1 shows the results of the durability test. Comparing between the amounts of the equivalent electrode active substance parts loaded, the life of the example sample 7 is 3.7 hours, whereas the comparison sample 2 is 1.2 hours and the example sample 8 is 52 hours. On the other hand, Comparative Sample 3 is 39.5 hours and Example Sample 9 is 372 hours, while Comparative Sample 4 is 182 hours and Example Sample 10 is 732 hours, while Comparative Sample 5 is 267 hours. It's time. From these, even when the composition of the electrode active material and the amount of the electrode active material supported are the same, the life varies greatly depending on the treatment method of the Ti substrate. It can be seen that has a longer life. This is because the amount of the electrode active substance part supported on the adhesion developing part, that is, the nanofiber part in the example is larger than the quantity supported on the adhesion developing part, that is, the roughened uneven part in the comparative example. This is considered to be due to the fact that it was much more and a stronger adhesion was expressed.

FIG. 7 shows a surface photograph of the sample after 1.7 hours of electrolysis in the durability test. FIG. 7A is an electrode surface photograph of Example Sample 7 and FIG. 7B is Comparative Example Sample 2. The Example Sample 7 and the Comparative Example Sample 2 differ only in the structure of the adhesion developing portion. The composition of the active substance part and the amount carried are the same.
The photo-like and black portions are the electrode active material portions, and the white portions are the portions where the electrode active material disappears and the Ti substrate is visible. In the comparative sample 2 in which the adhesion developing part is formed by the oxalic acid treatment, the electrode active material part is peeled and consumed, and the titanium of the substrate is exposed, whereas the nanofiber part is provided by the alkali treatment. In the sample 13 which is an example in which the adhesion developing portion is formed, the electrode active material portion is mostly retained. It can be said that the difference in adhesion between the roughened surface by the conventional oxalic acid treatment and the nanofiber portion by the alkali treatment of the present invention is remarkably shown.

FIG. 8 is a graph in which the horizontal axis represents the amount of Ir, which is the main electrode active material, and the vertical axis represents the durable electrolysis time. Basically, it can be seen that the electrode has a longer life as the amount of Ir supported increases. It should be noted here that the inclination differs depending on the difference in the pretreatment method of the Ti substrate. This is because the nanofiber portion on the surface of the Ti substrate according to the present invention exhibits a strong anchoring effect, so that the adhesion between the Ti substrate and the electrode active material is high, and a high voltage of 10 V to 50 V and a polarity Shows that the electrode for electrolysis that is periodically replaced has a very high resistance even under severe conditions.

10: Electrode for electrolysis 101: Substrate
102: Electrode active substance part 103: Adhesive force expression part 103a: Nanofiber part 103b: Rough surface part d1, d2: Nanofiber part thickness

Claims (15)

A conductive substrate mainly composed of Ti;
An electrode active material portion comprising an electrode active material containing a platinum group metal or an oxide thereof disposed on the surface of the substrate;
An electrode for electrolysis comprising an adhesion force-expressing part for improving adhesion between the substrate and the electrode active substance part,
The adhesion developing part has an insulating nanofiber part made of nanofibers made of TiO2 or titanate formed on the substrate,
The electrode active substance part is supported on at least a part of the nanofiber part,
The electrode for electrolysis characterized in that the nanofiber portion has a thickness capable of electrically connecting the substrate and the electrode active material portion. The electrode for electrolysis according to claim 1, wherein the nanofiber portion has a thickness of 10 nm or more and 10 µm or less. The electrode for electrolysis according to claim 1 or 2, wherein the nanofiber has a diameter of 200 nm or less. The electrode active material includes fine particles of the platinum group metal or oxide thereof,
The electrode for electrolysis according to claim 1 or 2, wherein the particle diameter of the fine particles is smaller than the fiber interval of the nanofiber portion. A protective layer is formed between the nanofiber part and the electrode active substance part,
The electrode for electrode according to claim 1, wherein at least a part of the protective layer carries the electrode active material part. The surface of the substrate has a rough surface portion with a specific surface area increased by a treatment by a blast treatment method, a chemical etching method using an acid solution, an electrolytic oxidation treatment method, or the like,
The electrode for electrolysis according to claim 1, wherein the nanofiber part is formed on the rough surface part. The thickness of the fiber portion formed on the rough surface portion is smaller than the thickness of the fiber portion when the fiber portion is directly formed without forming the rough surface portion on the surface, The electrode for electrolysis according to claim 5. The electrode for electrolysis according to any one of claims 1 to 6, which is used for an electrode for electrolysis used at a current density of 100 A / m 2 or more. It is used for the electrode for electrolysis of the electrolysis process accompanied by the cathodic phenomenon of the anode, or the electrode for electrolysis which periodically switches the positive and negative polarities of the electrode. electrode. The electrode for electrolysis according to any one of claims 1 to 8, wherein the electrode for electrolysis is used as an electrode for electrolysis for generating chlorine or hypochlorous acid by electrolyzing a solution containing chloride ions. A method for producing an electrode for electrolysis comprising an electroconductive substrate mainly composed of Ti and an electrode active material portion comprising an electrode active material containing a platinum group metal or oxide thereof disposed on the surface of the substrate. ,
A step of alkali-treating the substrate to form an insulating nanofiber portion made of nanofibers having a diameter of TiO2 or titanate;
A step of supporting at least a part of the electrode active substance part on the nanofiber part,
In the step of forming the nanofiber part, the nanofiber part has a thickness capable of electrically connecting the base and the electrode active substance part. The method for producing an electrode for electrolysis according to claim 10, wherein the electrode active material is an oxide of a white metal metal. The substrate further includes a step of forming a rough surface portion on the surface of the substrate by a blasting method, a chemical etching method using an acid solution, an electrolytic oxidation method, and the like to increase the specific surface area before the treatment,
The method for producing an electrode for electrolysis according to claim 10 or 11, further comprising a step of forming the nanofiber portion after the step of increasing the specific surface area.   The method for producing an electrode for electrolysis according to any one of claims 10 to 12, wherein the electrode active material is formed using a monomer or oligomer solution containing a metal ion as a starting material. The method for producing an electrode for electrolysis according to any one of claims 10 to 13, wherein the monomer or oligomer solution containing metal ions is an aqueous solution using a solvent as water.