JP2012172199A - Electrode for electrolysis and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for electrolysis, which contains organic substances effective for depositing a metal by an electrochemical reaction, can be used as an anode without oxidatively decomposing the substances, and preferentially generates electrolytic ozone, oxygen, hydrogen even in the case of using electrolyte containing halide salt or impurities.SOLUTION: The electrode for electrolysis has a catalyst layer, which is formed on a valve metal base and contains a platinum group metal and/or its oxide. On the catalyst layer, a porous body layer, which is a continuous pore structure having a metal-organic functional group, is formed by a sol-gel method in a crosslinked structure formed by metal-oxygen bonding.

Description

  The present invention relates to an electrode for electrolysis used in various electrochemical reactions (electroplating, electrowinning, metal recovery, water treatment, seawater electrolysis, water electrolysis), and more particularly, using an electrochemical reaction. In addition, the present invention relates to an electrode for electrolysis used as an anode for depositing metal, or an electrode for electrolysis that can preferentially generate electrolytic ozone, oxygen, and hydrogen even when using an electrolytic solution containing a halogen salt or impurities. .

  Conventionally, when copper plating is performed on a printed circuit board or the like, a soluble copper electrode has been used for the anode in order to replenish copper ions in the electrolytic plating solution that gradually decreases as the copper deposits.

  However, soluble copper electrodes are consumed by dissolution, so the distance between the electrodes cannot be kept constant and uniform plating is difficult, and the electrolyte is contaminated by sludge generated from impurities contained in the soluble copper electrode. There is a problem that the liquid composition management becomes complicated.

  This is a major problem that hinders the widespread use of soluble copper electrodes due to the recent demand for finer copper plating wiring and higher plating quality requirements.

In order to overcome the above problems, there are many examples in which an insoluble electrode is used as an anode.
This insoluble electrode is an electrode for electrolysis that has been conventionally used for producing chlorate, perchlorate, and the like by an electrochemical technique, and is composed of a metal substrate having a valve action such as titanium. Further, an electrode catalyst material containing a platinum group metal or a metal oxide thereof is formed, and is characterized by high chemical stability and dimensional stability.

  The above insoluble electrode is not only used for the production of conventional chlorates, but it can also suppress the generation of sludge by taking advantage of its high chemical stability and dimensional stability, and can form a uniform electrodeposition film. In recent years, it has also been used as an anode for electrolytic extraction of metal foils, electrolytic production of metal foils, galvanization of steel plates, high-purity oxygen generation, and the like.

  However, electrolytes such as metal electrowinning, electrolytic production of metal foil, and electroplating often contain various additives or impurities such as chlorine ions and bromine ions. In addition to the electrochemical reaction, side reactions such as oxidative decomposition reaction of additives and oxidation reaction of halogen ions occur, and there are new problems such as necessity of additive concentration control, hypochlorous acid concentration control and halogen gas countermeasures. Has surfaced.

  Therefore, the characteristics required as an electrode for electrolysis include those that are insoluble and exhibit high durability.

  In recent years, hydrogen and oxygen have attracted attention as alternatives to fossil energy. Various methods have been considered for producing hydrogen and oxygen, and one of the methods with the least environmental impact has been proposed in which water is electrolyzed using current generated by photovoltaic power generation. Yes.

  However, it is desirable to use seawater or river water to prepare pure water, so it is desirable to use seawater or river water. However, with current electrolysis electrodes, hypochlorite ions are produced and organic substances are oxidatively decomposed. However, there was a problem that the reduction reaction of calcium and nitrate ions occurred and the production efficiency of hydrogen and oxygen was very poor. Furthermore, the oxidative decomposition reaction of organic substances has a problem that the oxidation reaction potential is very high and the load applied to the insoluble electrode is large, which affects the electrode life.

  With respect to such problems, Patent Documents 1 and 2 suppress consumption of organic substances such as additives in the plating solution by forming an electrochemically inactive layer on the electrode catalyst layer. And a method of selectively performing only the target electrochemical reaction is disclosed.

  The non-electrochemically active layer is composed of valve metal oxide, tin oxide, or a mixture thereof. However, when a homogeneous valve metal oxide layer is formed to act as an anode, it is difficult to pass a current because of poor conductivity. In addition, it is possible to temporarily add conductivity by adding a doping agent to the electrochemically inactive layer. However, the electrode produced in such a way immediately has a valve metal oxide to prevent oxidation dissolution reaction. The electrode has a short life because it forms a passive film or functions as an electrode while the valve metal oxide layer itself is dissolved.

  Therefore, it is possible to consider a method in which a current is passed through the electrode while utilizing some cracks generated in the valve metal oxide layer by forming the valve metal oxide layer by a thermal decomposition method, but the electrolytic voltage increases. For this reason, the load applied to the electrode is increased, and the life of the electrode is similarly adversely affected. In order to improve the electrode life, a method of generating many cracks during heat treatment can be considered, but cracks are a factor that destroys the layer structure, and the valve metal oxide layer peels off due to a large amount of oxygen gas generated at the anode. Therefore, there is a problem that a high current density cannot be applied.

  Furthermore, the porous metal oxide layer produced by generating a large number of cracks during the heat treatment is composed of only metal-oxygen bonds, so it has a very high hydrophilicity. There was a problem that it was easy to reach the catalyst layer, and the effect of suppressing the consumption of organic substances was not sustained.

  Further, the use of a tin oxide layer as a different technique is also disclosed, but the tin oxide electrode is an electrode characterized by a relatively high oxidation potential, and therefore, the organic substance of the additive contained in the plating solution is There was also a problem that it was easily oxidized and decomposed.

  Therefore, in Patent Document 3, reaction selectivity is improved by using an electrode for electrolysis in which an inorganic porous material containing an organosilicon compound having an ion exchange group is bonded using a low softening point glass as an adhesive substance. Proposals have been made to suppress the consumption of various additives in the electrolyte.

  However, an inorganic porous layer having reaction selectivity by forming a low softening point glass on the electrode catalyst layer, separating the impurity layer and silicon dioxide using a spinodal decomposition reaction by heat treatment, and then immersing in a strong acid However, impurities such as potassium, magnesium, and calcium separated by the spinodal decomposition reaction by heat treatment penetrate not only into the electrode catalyst layer due to the thermal diffusion effect, but also reduce the electrode catalyst ability. There was a problem that the chemical stability was impaired and the electrode life was adversely affected.

  Further, in order to impart an ion exchange function to the formed inorganic porous material layer, the reaction between the organic sulfonic acid and the inorganic porous material layer needs to be performed at a temperature exceeding 100 ° C. for a long time. Since the acid causes a large damage to the electrode catalyst layer, the electrode substrate, and the interface thereof, it shortens the electrode life. In addition, an inorganic porous body layer can be formed by utilizing spinodal decomposition, but the electrochemical diffusion rate can be prevented, that is, the target substance such as hydroxide ions is an electrode catalyst. It was difficult to form homogeneous pores on an industrial scale that could reach the layers sufficiently.

  Accordingly, there is a strong demand for an electrode for electrolysis suitable for preferentially and selectively generating hydrogen or oxygen.

Special table 2003-503598 gazette JP-T-2006-503187 JP 2009-235467 A J. et al. Chinese Chem, Soc. , 28, 111-114 (1981)

  Electrochemical reaction, even if it contains an organic substance effective for depositing metal, an electrode for electrolysis that can be used stably as an anode without oxidative decomposition of such substance, or a halogen salt or impurity An object of the present invention is to provide an electrode for electrolysis suitable for preferentially and selectively generating electrolytic ozone, oxygen, and hydrogen even when using an electrolytic solution containing the electrolyte, and a method for manufacturing the same.

  Moreover, when it is used for those uses, it is providing the electrode excellent in durability, and its manufacturing method.

  That is, the present invention is as follows.

The first invention comprises a conductive substrate made of a valve metal,
An electrode for electrolysis having a platinum group metal and / or a catalyst layer containing an oxide thereof formed on the substrate,
An electrode for electrolysis, wherein a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond is formed on the catalyst layer.

  The second invention is characterized in that the platinum group metal and / or its oxide is at least one selected from the group consisting of iridium oxide, platinum, platinum oxide and ruthenium oxide. It is an electrode for electrolysis as described in the invention.

  In a third aspect of the present invention, the porous body layer having a continuous pore structure formed on the catalyst layer has a porosity of 40 to 80% and an average pore diameter of 0.01 to 20 μm. The electrode for electrolysis according to the first or second invention, wherein the electrode has a thickness in a range of 0.2 to 3 μm.

  A fourth invention is the electrode for electrolysis according to any one of the first to third inventions, wherein the molecular weight of the organic functional group is 16 to 240.

  In a fifth aspect of the invention, the conductive substrate made of a valve metal is a substrate made of at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum and vanadium or an alloy containing these metals as a main component. An electrode for electrolysis according to any one of the first to fourth inventions.

A sixth invention is a method for producing an electrode for electrolysis comprising a conductive substrate made of a valve metal and a catalyst layer containing a platinum group metal and / or an oxide thereof formed on the substrate.
Next steps (1) to (3),
(1) a step of roughening the surface of a conductive substrate made of a valve metal;
(2) A dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, platinum, and ruthenium is dispersed or dissolved is applied onto a metal substrate, dried, fired, and thermally decomposed. Forming a catalyst layer comprising the platinum group metal and / or oxide thereof;
(3) An organometallic alkoxide having an alkoxy group in part is used as a starting material and is prepared by a chemical reaction using a hydrophilic organic solvent, and the metal compound, its partial hydrolysis, and / or its partial weight An organic / inorganic composite precursor solution containing the condensate in an organic solvent is applied, dried, and heat-treated to form a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond Forming an electrode surface layer formed,
Including
A method for producing an electrode for electrolysis, comprising forming a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond on the catalyst layer.

  A seventh invention is characterized in that the metal in the organometallic alkoxide having an alkoxy group in part is at least one metal selected from the group consisting of niobium, zirconium, titanium, tantalum, aluminum, and silicon. It is a manufacturing method of the electrode for electrolysis given in the 6th invention.

  According to the present invention, a metal in a crosslinked structure by a metal-oxygen bond is formed on an electrode for electrolysis in which a catalyst layer containing an electrochemically active platinum group metal oxide is formed on a conductive substrate made of a valve metal. -By providing a porous body layer having an organic functional group and a continuous pore structure, the adhesion between the catalyst layer and the porous body layer having a continuous pore structure can be dramatically improved. Only the electrolysis reaction of water can be selectively performed by the effect of preferentially permeating water.

  That is, a reactive organometallic alkoxide having a part of an alkoxy group is used as a starting material, and has a metal-organic functional group in a cross-linked structure by a metal-oxygen bond on the catalyst layer using a hydrolysis / polycondensation reaction. By forming a porous body layer that has a continuous pore structure, even when a large current density is applied, the release of the generated gas is facilitated by the water repellent effect of the organic functional group site, and the pressure is relieved. It is possible to prevent the layer from peeling off from the catalyst layer. Organic-inorganic composite materials formed by the sol-gel method have a porous structure with a uniform and fine pore size. Organic compounds with a large molecular size such as additives contained in the plating solution, chlorine ions and bromine ions with a large ion radius. Since it is difficult to permeate through the porous structure, etc., it becomes possible to selectively perform only water electrolysis reaction by preferentially permeating water molecules.

It is a figure which shows the production | generation efficiency when using each electrode prepared in the Example and the comparative example, and performing the hypochlorite ion production | generation test. It is a figure which shows the raise rate of the electrolysis voltage when using each electrode prepared by the Example and the comparative example, and performing the hypochlorite ion production | generation test. It is a figure which shows the raise rate of the electrolysis voltage when using each electrode prepared in the Example and the comparative example, and performing the hydrogen production | generation test.

  In the electrode for electrolysis of the present invention, the environment used is often highly acidic, such as a plating solution or an electrolytic solution for electrowinning. Therefore, the material of the conductive substrate made of the valve metal used exhibits high corrosion resistance. A conductive substrate is preferable, and at least one conductive substrate selected from the group consisting of titanium, zirconium, niobium, tantalum, and vanadium alloys as main components is preferable.

  In order to reinforce the adhesion between the conductive substrate and the catalyst layer containing the platinum group metal oxide, the surface of the metal substrate is subjected to blasting, etching treatment, etc., to increase the surface area and roughen the surface before forming the catalyst layer. It is preferable to use the same. The form of the conductive substrate is not particularly limited, and plate-like, rod-like, linear, mesh-like, sheet-like, tubular, lath-like, etc. can be used.

  After blasting or etching treatment, the surface can be selectively etched to be cleaned and activated. Typical examples of the acid cleaning in this cleaning are sulfuric acid, hydrochloric acid, hydrofluoric acid, and the like, and activation can be performed by immersing the metal substrate in these solutions to dissolve a part of the surface.

  After activating the surface by the method described above, a catalyst layer containing a platinum group metal oxide can be formed. For the formation of the catalyst layer, a solution containing platinum group metal salts as a catalyst layer component is applied, and a sol-gel method or thermal decomposition, which is film formation by hydrolysis / polycondensation or thermal decomposition reaction in an oxygen-containing atmosphere. , Physical vapor deposition methods such as sputtering and vapor deposition, chemical vapor deposition methods using organometallic materials, etc., but after applying a solution in which a platinum group metal salt or the like is dissolved in butanol to a conductive substrate A thermal decomposition method is preferred in which heat treatment is performed in an oxygen-containing atmosphere to form an incomplete metal-oxygen bond in the catalyst layer, thereby increasing conductivity and increasing corrosion resistance due to the amorphous structure.

  A coating method for forming a catalyst layer containing a platinum group metal and / or an oxide thereof by a sol-gel method or a thermal decomposition method is not particularly limited, and a conventionally known method can be used. For example, a spray coating method, The spraying method, curtain flow coating method, doctor blade method, dip coating method, brush coating method, spin coating method, etc. can be used to repeat the heat treatment step until the desired film thickness is obtained.

  The platinum group metal and / or its oxide is preferably one containing at least one selected from the group consisting of iridium dioxide, ruthenium dioxide, platinum, platinum oxide, rhodium oxide, and palladium oxide. It is preferable to use at least one selected from the group consisting of iridium dioxide, ruthenium dioxide, platinum, and platinum oxide from the viewpoint of catalytic activity against the above.

  Further, when durability is particularly required, a platinum group metal layer and / or its oxidation can be obtained by further adding an organometallic compound or chloride of titanium, zirconium, tantalum, niobium, vanadium, tin to the coating solution. The corrosion resistance of the physical layer can be improved. As a ratio to be added, it is preferable that the coating liquid is prepared so as to be 20 to 50 mol% for tantalum, vanadium and niobium, and 5 to 20 mol% for titanium, zirconium and tin. Particularly preferred is a composition comprising iridium oxide and tantalum oxide, and 40 to 50 mol% of tantalum is added to the coating solution.

Next, a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond is formed on the catalyst layer.
Here, the definition of each word will be described.
Since the use of metal alkoxide is specifically assumed as the metal-oxygen bond, it refers to a bond between the metal used and an oxygen atom present in the alkoxy group.
Specifically, the cross-linked structure refers to a state in which polymeric titanium dioxide is appropriately condensed to form a network structure.
The metal-organic functional group specifically refers to a bond between an organic functional group contained in the used metal alkoxide and a metal.
The continuous pore structure refers to a pore structure formed by continuous bonding with the metal-organic functional group in the crosslinked structure.
Therefore, in the continuous pore structure referred to in the present application, a metal-oxygen bond and a metal-organic functional group bond are essential.

  As a method for synthesizing a cross-linked structure by metal-oxygen bond at low temperature, a sol-gel method or a thermal decomposition method can be considered. However, a porous body layer can be formed at a lower temperature and a more complete metal-oxygen bond can be formed. Thus, a sol-gel method that can increase electrochemical inactivity is preferable.

The sol-gel method is a method in which a hydrolyzable metal alkoxide having an organic functional group that does not contribute to hydrolysis / polycondensation reaction is dissolved in a hydrophilic organic solvent, and 1 to 3 mol equivalent to the metal alkoxide content. An organic / inorganic composite precursor raw material solution containing a partial hydrolysis of the compound and / or a partial polycondensate thereof is prepared by adding water, further adding an acid catalyst or an alkali catalyst, and hydrolysis / polycondensation reaction, In this method, a solution is applied onto the catalyst layer, dried, and then subjected to heat treatment in a crystallization temperature range to form a crosslinked structure by metal-oxygen bonds.
This method is called a sol-gel method because a sol precursor solution is prepared in advance and gelled by a drying process.

Hydrolysis / polycondensation reaction can be carried out by adding 1 to 3 mol times the amount of metal alkoxide having an organic functional group that does not contribute to hydrolysis / polycondensation reaction. -A cross-linked structure due to oxygen bonds is not formed.
In addition, it is suitable to use a hydrophilic solvent in order to perform the hydrolysis / polycondensation reaction uniformly. The hydrophilic solvent used in the reaction is preferably an alcohol having 1 to 6 carbon atoms, such as methanol, ethanol, n-propanol, i-propanol, n-butanol, 2-methyl-1-propanol, 2-butanol, 2 -Methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl- Examples include 2-butanol, 2,2-dimethyl-1-propanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, and cyclohexanol.

  The porous body layer having a continuous pore structure is formed by removal of the solvent and water from the organic functional group site that does not contribute to the hydrolysis / polycondensation reaction in the crosslinked structure formed by the metal-oxygen bond formed during the heat treatment. The molecular weight of the organic functional group is 16 to 240 because it is necessary to have both water repellency and hydrophilic properties that preferentially move only the target water molecules to the catalyst layer during electrolysis. Preferably it is. Examples of the organic functional group include an alkyl group, a carbonyl group, a phenyl group, an amino group, a diazo group, and a phosphino group.

  As a metal of a hydrolyzable metal alkoxide having an organic functional group that does not contribute to hydrolysis / polycondensation reaction, a cross-linked structure by a metal-oxygen bond that can withstand an electrolyte having strong acidity or strong oxidation is formed. Therefore, it is preferable that the metal is at least one metal selected from the group consisting of niobium, zirconium, titanium, tantalum, aluminum, and silicon. Among these, silicon that is excellent in both water repellency and hydrophilic properties that preferentially move only water molecules of interest during electrolysis to the catalyst layer and durability is particularly preferable.

  The organic inorganic composite precursor raw material solution is applied and dried, and then a porous body layer, which is a crosslinked structure formed by metal-oxygen bonds, is formed by heat treatment in the crystallization temperature range. It is suitable that the heat treatment temperature is 150 to 400 ° C. so that the functional group is not oxidatively decomposed, and the hydrolysis / polycondensation reaction is controlled so as to crystallize in this temperature range. Adjust.

  The porous body layer having a continuous pore structure formed by heat treatment on the catalyst layer described above preferably has a porosity of 40 to 80% from the viewpoint of desorption of generated oxygen and hydrogen gas. 50 to 70% is more preferable.

Here, the porosity is the following formula porosity (%) = {1− (A / B)} × 100
Is a numerical value calculated by
Here, A indicates the apparent density (g / cm ³ ), and B indicates the theoretical density (g / cm ³ ). A and B are values that can be measured and calculated by the Archimedes method.

In addition, the porous body layer having a continuous pore structure formed on the catalyst layer has an average pore diameter of 0.01 to from the viewpoint of efficiency of preferentially transferring only the target water molecules to the catalyst layer. The range of 20 μm is preferable, but the range of 0.01 to 10 μm is more preferable, and the range of 0.01 to 5 μm is most preferable.
Here, the pore diameter (μm) indicates an average diameter of continuous pores in the porous body layer, and is a value that can be measured by, for example, an X-ray small angle scattering method or a transmission electron microscope observation method.

Further, the porous body layer having a continuous pore structure formed on the catalyst layer has an average film thickness of 0.3 from the viewpoint of efficiency and economical viewpoint of preferentially transferring only the target water molecules to the catalyst layer. A range of 2 to 3 μm is preferred.
The film thickness (μm) indicates the thickness from the surface of the catalyst layer to the surface of the porous body layer, and can be measured by, for example, cross-sectional observation with a scanning electron microscope or a fluorescent X-ray film thickness measuring device. It is.

  By the way, a catalyst layer made of a platinum group metal layer and / or an oxide layer thereof is then formed on a conductive substrate made of a valve metal in advance after bending such as press working, machining, etching, etc., and then an upper layer thereof. By forming a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond, the catalyst layer and the porous body layer can be formed even when forming a substrate having a complicated shape. An electrode for electrolysis for preferentially generating electrolytic ozone, oxygen, and hydrogen can be obtained without damage. For example, regarding the formation of a porous body layer, if the catalyst layer and the porous body layer are sequentially formed on the substrate after processing as described above, even if the substrate surface is uneven by processing, it is uniform. Thus, it is possible to form each layer and to obtain stable electrode performance.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by this Example.

Example 1
Tetraethoxyacetylacetonato-tantalum (23.0 g), cyclopentanol (8 ml), butanol (74 ml), acetylacetone (10 ml), 1N hydrochloric acid (0.05 ml) and pure water (0.45 g) were mixed and maintained at 5 ° C., and stirred for 10 hours in a nitrogen atmosphere. Then, 100 ml of an organic-inorganic composite precursor material solution having a tantalum concentration of 0.5 M was prepared by performing hydrolysis and polycondensation reaction.

  A Ti substrate (JIS type 1) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 2.0 mm. The substrate was finished with a satin finish by shot blasting using a zircon shot. Next, after degreasing treatment with an organic solvent, the oxide substrate was removed by immersion in 3N hydrochloric acid for 30 seconds to complete the Ti substrate surface treatment step.

  A catalyst coating solution was prepared by mixing 25.9 g of hexachloroplatinic acid hexahydrate and 90 ml of butanol and stirring for 8 hours under a nitrogen atmosphere. After applying the surface treatment process on the Ti substrate by brush coating, the process of drying at 100 ° C. for 10 minutes and heat treatment at 500 ° C. for 1 hour is repeated 10 times to form a PtO layer having a thickness of 1 μm. Thus, the catalyst layer forming step of the PtO—Pt oxide was completed.

  Next, a step of applying an organic-inorganic composite precursor raw material solution containing tantalum prepared previously on the Ti base material that has completed the catalyst layer forming step by a brush coating method and performing a heat treatment at 150 ° C. in air for 1 hour. Electrolysis in which a porous body layer having a continuous pore structure having a tantalum-carbonyl group in a crosslinked structure with a tantalum-oxygen bond having a porosity of 60%, an average pore diameter of 1.2 μm, and a thickness of 2 μm was formed by repeating twice. Ten electrodes in total were produced.

(Example 2)
While stirring at 11.degree. C. for 10 hours under a nitrogen atmosphere, 11.1 g of 3-aminopropyltriethoxy-silane, 8 ml of cyclopentanol, 84 ml of ethanol, 1.0 ml of 1N ammonia water and 1.8 g of pure water were mixed and kept at 5.degree. Then, 100 ml of an organic-inorganic composite precursor material solution having a silicon concentration of 0.5 M was prepared by performing hydrolysis and polycondensation reaction.

  A Ti substrate (JIS type 1) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 2.0 mm. The substrate was dipped in a 5N hydrochloric acid aqueous solution at 80 ° C. for 5 hours to give a satin finish. Next, after the degreasing treatment with an organic solvent, the oxide film was removed by immersion in 0.1N hydrofluoric acid for 30 seconds, and the Ti substrate surface treatment step was completed.

Ruthenium trichloride trihydrate (10.5 g) and butanol (70 ml) were mixed and stirred in a nitrogen atmosphere for 1 hour. Further, acetylacetone (5 ml), titanium (IV) -t-butoxide (3.4 g) and butanol (20 ml) were added successively and stirred for 5 hours. Thus, a catalyst coating solution for RuO ₂ —TiO ₂ oxide was prepared. After applying the surface treatment process on the Ti substrate by a brush coating method, the process of drying at 100 ° C. for 10 minutes and heat-treating at 480 ° C. for 1 hour is repeated 10 times, thereby RuO ₂ having a thickness of 2.5 μm. to form a -TiO ₂ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying the previously prepared silicon-containing organic-inorganic composite precursor solution by brush coating on the Ti substrate that has finished the catalyst layer forming step and performing a heat treatment at 200 ° C. in air for 1 hour. By repeating twice, a porous body layer having a continuous pore structure having a niobium-aminopropyl group in a crosslinked structure by a silicon-oxygen bond having a porosity of 75%, an average pore diameter of 0.6 μm, and a thickness of 1.5 μm A total of 10 electrodes for electrolysis were formed.

(Example 3)
Diphenyldiethoxide-silane (13.6 g), cyclopentanol (8 ml), ethanol (84 ml), 1N aqueous ammonia (1.0 ml) and pure water (1.8 g) were mixed and maintained at 5 ° C., and stirred for 10 hours under a nitrogen atmosphere to add water. By performing the decomposition / polycondensation reaction, 100 ml of an organic-inorganic composite precursor raw material solution having a silicon concentration of 0.5 M was prepared.

  A Ti substrate (JIS type 1) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 2.0 mm. The substrate was dipped in a 5N hydrochloric acid aqueous solution at 80 ° C. for 5 hours to give a satin finish. Next, after the degreasing treatment with an organic solvent, the oxide film was removed by immersion in 0.1N hydrofluoric acid for 30 seconds, and the Ti substrate surface treatment step was completed.

7.6 g of iridium trichloride trihydrate and 70 ml of butanol were mixed and stirred for 1 hour under a nitrogen atmosphere. Further, 5 ml of acetylacetone, 11.6 g of tantalum (V) -t-butoxide and 20 ml of butanol were successively added and stirred for 5 hours. Thus, a catalyst coating solution for IrO ₂ —TaO ₂ -based oxide was prepared. After applying the surface treatment step on the Ti substrate by a brush coating method, the step of drying at 100 ° C. for 10 minutes and performing heat treatment at 500 ° C. for 1 hour is repeated 10 times, so that IrO ₂ with a thickness of 4.0 μm is obtained. to form a -ta ₂ O ₅ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying the previously prepared silicon-containing organic-inorganic composite precursor solution by brush coating on the Ti substrate that has finished the catalyst layer forming step and performing a heat treatment at 200 ° C. in air for 1 hour. By repeating twice, a porous body layer having a continuous pore structure having a niobium-phenyl group in a crosslinked structure by a silicon-oxygen bond having a porosity of 67%, an average pore diameter of 0.7 μm, and a thickness of 1.5 μm is formed. A total of 10 electrolysis electrodes were produced.

Example 4
13.6 g of pentamethylcyclopentadienyl-titanium-trimethoxide, 8 ml of cyclopentanol, 84 ml of butanol, 0.1 ml of 1N hydrochloric acid and 0.1 g of pure water were mixed and kept at 5 ° C., and stirred for 10 hours in a nitrogen atmosphere. Then, 100 ml of an organic-inorganic composite precursor raw material solution having a titanium concentration of 0.5 M was prepared by performing a hydrolysis / polycondensation reaction.

  An Nb substrate was used as the metal substrate. The Nb substrate is a rolled material having a size of 20 × 30 mm and a thickness of 2.0 mm. The substrate was finished with a satin finish by shot blasting using a zircon shot. Next, after the degreasing treatment with an organic solvent, the oxide film was removed by immersion in 6N hydrofluoric acid for 1 minute, and the Nb substrate surface treatment step was completed.

7.6 g of iridium trichloride trihydrate and 70 ml of butanol were mixed and stirred for 1 hour under a nitrogen atmosphere. Further, 5 ml of acetylacetone, 11.6 g of tantalum (V) -t-butoxide and 20 ml of butanol were successively added and stirred for 5 hours. Thus, a catalyst coating solution for IrO ₂ —TaO ₂ -based oxide was prepared. After applying the surface treatment step on the Ti substrate by a brush coating method, the step of drying at 100 ° C. for 10 minutes and performing heat treatment at 500 ° C. for 1 hour is repeated 10 times, so that IrO ₂ with a thickness of 4.0 μm is obtained. to form a -ta ₂ O ₅ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying the previously prepared titanium-containing organic-inorganic composite precursor solution by brush coating on the Nb substrate that has completed the catalyst layer forming step and performing a heat treatment at 250 ° C. in air for 1 hour. By repeating twice, a porous body having a continuous pore structure having a titanium-pentamethylcyclopentadienyl group in a crosslinked structure by a titanium-oxygen bond having a porosity of 55%, an average pore diameter of 1.7 μm, and a thickness of 1 μm A total of 10 electrodes for electrolysis having a layer formed thereon were produced.

(Example 5)
Referring to Non-Patent Document 1, 30 g of red-brown solid bis (cyclopentadienyl) -niobium-triphenoxide was synthesized in an argon atmosphere using niobium chloride (V) as a starting material in a yield of 13%. While mixing 25.8 g of synthesized bis (cyclopentadienyl) -niobium-triphenoxide, 43 ml of cyclopentanol, 43 ml of i-propanol, 0.5 ml of 1N hydrochloric acid and 0.9 g of pure water and maintaining at 5 ° C., nitrogen was added. 100 ml of organic-inorganic composite precursor raw material solution having a niobium concentration of 0.5 M was prepared by performing a hydrolysis / polycondensation reaction by stirring for 10 hours under an atmosphere.

  A Zr substrate was used as the metal substrate. The Zr substrate is a rolled material having a size of 20 × 30 mm and a thickness of 2.0 mm. The substrate was finished with a satin finish by shot blasting using a zircon shot. Next, after degreasing treatment with an organic solvent, the oxide film was removed by dipping in 1N hydrofluoric acid for 15 seconds to complete the Zr substrate surface treatment step.

7.6 g of iridium trichloride trihydrate and 70 ml of butanol were mixed and stirred for 1 hour under a nitrogen atmosphere. Further, 5 ml of acetylacetone, 11.6 g of tantalum (V) -t-butoxide and 20 ml of butanol were successively added and stirred for 5 hours. Thus, a catalyst coating solution for IrO ₂ —TaO ₂ -based oxide was prepared. After applying the surface treatment process on the Zr substrate by brush coating, the process of drying at 100 ° C. for 10 minutes and heat-treating at 500 ° C. for 1 hour is repeated 10 times, thereby giving IrO ₂ with a thickness of 4.0 μm. to form a -ta ₂ O ₅ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying an organic-inorganic composite precursor raw material solution containing niobium prepared previously on the Zr base material after the catalyst layer forming step by a brush coating method and performing a heat treatment at 250 ° C. in air for 1 hour. By repeating twice, a porous body layer having a continuous pore structure having a niobium-cyclopentadionyl group in a crosslinked structure with a niobium-oxygen bond having a porosity of 70%, an average pore diameter of 0.7 μm, and a thickness of 1 μm is obtained. A total of 10 electrodes for electrolysis were formed.

(Example 6)
A mixture of 13.7 g of aluminum-diisopropoxide ethyl acetoacetate, 90 ml of butanol, 1.0 ml of 1N hydrochloric acid, and 0.9 g of pure water was maintained at 5 ° C. and stirred for 10 hours in a nitrogen atmosphere to hydrolyze By performing the condensation reaction, 100 ml of an organic-inorganic composite precursor material solution having an aluminum concentration of 0.5 M was prepared.

  A Ta substrate was used as the metal substrate. The Ta substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 mm. The base was finished by shot blasting using zirconium carbide. Next, after the degreasing treatment with an organic solvent, the oxide film was removed by dipping in 1N hydrofluoric acid for 15 seconds, and the Ta substrate surface treatment step was completed.

7.6 g of iridium trichloride trihydrate and 70 ml of butanol were mixed and stirred for 1 hour under a nitrogen atmosphere. Further, 5 ml of acetylacetone, 11.6 g of tantalum (V) -t-butoxide and 20 ml of butanol were successively added and stirred for 5 hours. Thus, a catalyst coating solution for IrO ₂ —TaO ₂ -based oxide was prepared. After applying the surface treatment step on the Ti substrate by a brush coating method, the step of drying at 100 ° C. for 10 minutes and performing heat treatment at 500 ° C. for 1 hour is repeated 10 times, so that IrO ₂ with a thickness of 4.0 μm is obtained. to form a -ta ₂ O ₅ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying an organic-inorganic composite precursor raw material solution containing aluminum prepared previously on the Ta substrate that has completed the catalyst layer forming step by a brush coating method and performing a heat treatment at 250 ° C. in air for 1 hour. By repeating twice, a porous body layer having a continuous pore structure having an aluminum-carbonyl group in a crosslinked structure by an aluminum-oxygen bond having a porosity of 75%, an average pore diameter of 0.9 μm, and a thickness of 1.5 μm is formed. A total of 10 electrolysis electrodes were produced.

(Example 7)
Zirconium dimethacrylate dibutoxide 18.9 g, butanol 45 ml, toluene 40 ml,
An organic inorganic compound having a zirconium concentration of 0.5 M is obtained by mixing 0.2 ml of 1N hydrochloric acid and 0.9 g of pure water and holding the mixture at 5 ° C. for 10 hours under a nitrogen atmosphere to conduct hydrolysis and polycondensation reaction. 100 ml of the composite precursor material solution was prepared.

  A V substrate was used as the metal substrate. The V substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 mm. The base was finished by shot blasting using zirconium carbide. Next, after the degreasing treatment with an organic solvent, the oxide film was removed by immersing in 1N hydrofluoric acid for 15 seconds to complete the V substrate surface treatment step.

7.6 g of iridium trichloride trihydrate and 70 ml of butanol were mixed and stirred for 1 hour under a nitrogen atmosphere. Further, 5 ml of acetylacetone, 11.6 g of tantalum (V) -t-butoxide and 20 ml of butanol were successively added and stirred for 5 hours. Thus, a catalyst coating solution for IrO ₂ —TaO ₂ -based oxide was prepared. After applying the surface treatment step on the Ti substrate by the brush coating method, the step of drying at 100 ° C. for 10 minutes and performing the heat treatment at 500 ° C. for 1 hour is repeated 10 times, so that IrO ₂ with a thickness of 4.1 μm is obtained. to form a -ta ₂ O ₅ oxide layer, to complete the catalyst layer forming step.

  Next, a step of applying an organic-inorganic composite precursor raw material solution containing zirconium prepared previously on the V base material after the catalyst layer forming step by a brush coating method and performing a heat treatment at 200 ° C. in air for 1 hour. Electrolysis in which a porous body layer having a continuous pore structure having a vanadium-carbonyl group in a crosslinked structure by vanadium-oxygen bonds having a porosity of 65%, an average pore diameter of 2.1 μm, and a thickness of 2 μm was formed by repeating twice. Ten electrodes in total were produced.

(Comparative Example 1)
In accordance with the method for producing an inorganic oxide film described in Patent Document 1, an electrode for electrolysis was produced. Specifically, the coating film solution formed on the catalyst layer was prepared as an inorganic oxide forming coating solution in which tantalum chloride was dissolved in hydrochloric acid and diluted 50:50 with isopropanol.

  The metal base and the PtO—Pt-based oxide catalyst layer to be used were implemented in the same manner as in Example 1, and then the inorganic oxide-forming coating solution prepared above was applied onto the catalyst layer, and then at 100 ° C. for 3 minutes. The process of drying and heat-treating at 525 ° C. for 10 minutes was repeated 10 times to produce a total of 10 electrodes for electrolysis having a tantalum oxide layer with many cracks.

(Comparative Example 2)
In Example 1, 27.3 g of tantalum (V) -n-butoxide having no functional group in the molecule that cannot contribute to the dehydration / polycondensation reaction was used, and the other raw materials and processes used were the same as in Example 1. Then, a total of 10 electrodes for electrolysis were formed on which a tantalum oxide layer having a porosity of 46% and a number of cracks having a thickness of 2 μm was formed.

(Comparative Example 3)
In Example 2, the same procedure was performed except that 10.4 g of tetraethoxy-silane having no functional group that cannot contribute to the dehydration / polycondensation reaction in the molecule, and cracks with a porosity of 23% and a thickness of 2.5 μm were observed. A total of 10 electrodes for electrolysis in which a large number of silicon dioxide oxide layers were formed were produced.

(Comparative Example 4)
In Example 2, the same procedure was performed except that the amount of pure water used in the preparation of the organic / inorganic composite precursor material solution having a silicon concentration of 0.5 M was 0 g, and the porous body layer formation temperature was 500 ° C., and the porosity was 85%. A total of 10 electrodes for electrolysis in which a porous silicon dioxide layer having an average pore size of 0.7 μm and a thickness of 0.05 μm was formed.

(Comparative Example 5)
In Example 3, the step of forming a porous body layer having a continuous pore structure was omitted, and a total of 10 electrodes for electrolysis were formed in which only the catalyst layer of IrO ₂ —Ta ₂ O ₅ oxide was formed.

(Comparative Example 6)
In Example 3, the same procedure was performed except that the raw material in the preparation of the organic / inorganic composite precursor raw material solution having a silicon concentration of 0.5 M was diphenylsilanodiol of 10.82 g and the amount of pure water used was 0 g. A total of 10 electrodes for electrolysis were formed on which a silicon dioxide-based layer having many 1.5 μm cracks was formed.

(Comparative Example 7)
Ten electrodes on which an IrO ₂ —Ta ₂ O ₅ oxide layer having a catalyst layer formation thickness of 4.0 μm was formed after the Ti substrate surface treatment by the method described in Example 3 were prepared. Next, according to Patent Document 1, a layer having reaction selectivity was formed on the catalyst layer.

Specifically, a glaze (Loppet Kobata Electric Industry Co., Ltd., Cloisonne glazed glaze, R101, white transparent, main component is 39% feldspar, 33% silica) was added to the mortar and crushed finely. Distilled water was added to the crushed glaze at a volume ratio of 1: 1, and kneaded until the glaze became a paste.
Next, a paste-like glaze was applied to the electrode with a brush so that the thickness of the coating layer was 0.5 mm. Thereto were placed porous glass particles (pore diameter 30 nm, surface area 80 m ² / g) to 50 mg / cm ² and sufficiently dried naturally.

  After drying, the electrode was heated in an electric furnace at 650 ° C. for 30 minutes. In order to clean the glass surface, a small amount of dilute hydrochloric acid and an electrode were placed in the flask, vacuum-dried at 200 ° C. for 24 hours, and then naturally cooled until the temperature returned to room temperature. (3-Mercaptopropyl) -trimethyl-silane ((3-mercaptopropyl) trimethoxysilane) and 3.1-propane sultone (3,1-propanesultone) were dissolved in toluene so that the molar ratio was 6: 4. Then, the electrode was immersed in the solution under a nitrogen atmosphere. Heating under reflux was performed at 120 ° C. for 12 hours under an anhydrous nitrogen atmosphere. Then, after waiting for the temperature to drop in a nitrogen atmosphere, the electrodes were washed with toluene to produce a total of 10 electrodes for electrolysis having reaction selectivity.

With respect to the electrode for electrolysis according to the present invention thus produced and the electrode of the comparative example, 170 g / L of sulfuric acid was used as the supporting electrolyte, and bis (3-sulfopropyl) sulfide-2-sodium (hereinafter, “ Abbreviated as “SPS”.) Using an electrolyte prepared to be 5 g / L, using an electrode for electrolysis as an anode, a platinum electrode as a cathode, and a silver / silver chloride electrode as a reference electrode, a current density of 20 A / L An SPS oxidative decomposition test was conducted for 24 hours by dm ² and an electrolyte temperature of 25 ° C. by tripolar constant current electrolysis. Thereafter, Table 1 shows the result of comparing the SPS residual ratio calculated by carrying out quantitative analysis of SPS by capillary electrophoresis / mass spectrometry and the potential (vs silver / silver silver chloride electrode). Table 2 shows the result of comparing the SPS concentration when the electrolytic oxidation decomposition test was repeated 85 times (after 2040 hours) and the potential (vs silver / silver silver chloride electrode).

Next, with respect to the produced electrode for electrolysis according to the present invention (Examples 1 and 3) and comparative examples (1, 5, and 7), a 3% sodium chloride aqueous solution was used as an electrolyte solution, and the electrode for electrolysis was used as an anode. A hypochlorite ion production test by constant current electrolysis using a stainless steel SUS304 electrode as a cathode at a distance of 5 mm, a current density of 15 A / dm ² , an electrolyte flow rate of 20 ml / ml, and an electrolyte temperature of 25 ° C. For 4000 hours. FIG. 1 and FIG. 2 show the results of calculating the chlorine generation efficiency by performing quantitative determination of hypochlorite ions by iodine titration at any time during the test and comparing the results with the electrolysis voltage.

Further, for the produced electrode for electrolysis according to the present invention (Example 1) and Comparative Examples (1, 2), sodium metasilicate 0.005M + calcium hydrogen carbonate 0.001M + sodium hydroxide 0.01M. Using the prepared alkaline electrolyte, a flow type H-type cell for the electrolytic cell, an IrO ₂ -Ta ₂ O ₅ oxide electrode for the anode, and an electrode for electrolysis at the cathode so that the gap is 40 mm, the current density A hydrogen generation test by constant current electrolysis was performed for 1000 hours under the conditions of 15 A / dm ² and an electrolyte temperature of 25 ° C. The result of comparing the electrolysis voltage at any time during the test is shown in FIG.

According to the results of Table 1, the SPS remaining rate is 58% in the conventional electrode (Comparative Example 5) in which only the catalyst layer is formed, while the electrolysis is performed using the electrode for electrolysis according to the present invention. In this case, it was confirmed that the SPS remaining rate was 98% or more, electrolysis was possible at a potential of 1.9 V or less, and the effect of decomposing only water while suppressing the oxidative decomposition of organic matter was high. In contrast, the electrolysis electrodes (Comparative Examples 1 and 3) having a porous body layer having only a crosslinked structure by metal-oxygen bonds have higher hydrophilicity than the Examples, and therefore the SPS residual rate is 90% or less. Thus, the effect of suppressing the oxidative decomposition of organic matter was inferior. Moreover, since the electrode for electrolysis (Comparative Example 4) having a porous layer formed from an organic-inorganic composite precursor raw material solution that was not subjected to hydrolysis / polycondensation reaction is very thin, the SPS residual rate Was less than 70%, and the effect of suppressing the oxidative decomposition of organic matter was very poor.
Furthermore, an electrode for electrolysis (Comparative Examples 2 and 6) having a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond produced by a thermal decomposition method is metal-oxygen. Since the bonding structure is incomplete and conductive, it was confirmed that it functions as an electrode and the SPS residual rate is lowered.

  According to the results in Table 2, the voltage increased to 3.3 V or more in the conventional electrode (Comparative Example 5) in which only the catalyst layer used for 2000 hours or more was formed, and the SPS residual ratio was 49%. On the other hand, when electrolysis was performed using the electrode for electrolysis according to the present invention, the voltage was 3.1 V or less and the SPS residual ratio was maintained at 90% or more, and it was confirmed that the electrode life was long. On the other hand, in the electrode for electrolysis (Comparative Examples 1 and 3) having a porous body layer having only a crosslinked structure by metal-oxygen bond, a part of the porous body layer is peeled off due to the generation of oxygen gas. It was found from the SEM observation of the electrode surface that the layer was also damaged and the electrolysis voltage increased, and it was found that the electrode life tends to be short. In addition, the electrode for electrolysis (Comparative Example 4) having a porous layer formed from an organic-inorganic composite precursor raw material solution that was not subjected to hydrolysis / polycondensation reaction was very thin and disappeared during the test. Therefore, the same result as in Comparative Example 5 was obtained. Furthermore, an electrode for electrolysis (Comparative Examples 2 and 6) having a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond produced by a thermal decomposition method is a metal- Because the oxygen bond structure is incomplete and conductive, part of the porous membrane is peeled off due to its function as an electrode, and the catalyst layer is damaged at that time, so the electrolysis voltage is as high as 3.5 V or more, so the life of the electrode It has been confirmed that tends to be shorter. In the electrode for electrolysis (Comparative Example 7) having a porous body layer having an ion exchange group produced by the method described in Patent Document 1, the porous body layer remains after the 65th electrolytic oxidation decomposition test (after 1560 hours). However, due to the deterioration of the catalyst layer, the voltage became 6 V and electrolysis became impossible.

  According to the result of FIG. 1, in the electrode for electrolysis (Comparative Example 5) in which nothing is formed on the catalyst layer, although the generation efficiency of hypochlorite ions was 90% or more, the metal oxide ( In Comparative Example 1), a porous layer having a continuous pore structure having metal-organic functional groups (Examples 1 and 3) and a porous body having an ion exchange group (Comparative Example 7), up to 2000 hours have passed. It was confirmed that the production efficiency of hypochlorite ions can be suppressed to 50% or less.

  According to the result of FIG. 2, the electrode for electrolysis (Comparative Example 5) in which nothing is formed on the catalyst layer tends to increase the electrolysis due to the generation of chlorine and shorten the electrode life. In the electrode for electrolysis (Examples 1 and 3) in which a porous layer having a continuous pore structure having a group is formed, the electrolysis voltage can be maintained at 7 V or less even after 4000 hours, and the electrolysis can be continued. confirmed. On the other hand, the electrode for electrolysis (Comparative Example 1) formed with tantalum oxide can be electrolyzed only for 3500 hours, and when failure analysis was performed after the test was completed, it was thought that the metal oxide was considered to have peeled off due to the stress caused by gas generation. It was found that a thin film was observed in the electrolytic solution, and the catalyst layer was peeled off at the same time, resulting in an increase in the electrolysis voltage and a short life. In addition, the electrolytic electrode formed with the porous body having the ion exchange group (Comparative Example 7) can be electrolyzed only for 2600 hours. When the failure analysis was performed at the end of the test, the porous body layer on the catalyst layer remained. It was found that the electrolysis voltage was increased and the life was shortened because impurities were mixed in the catalyst layer during spinodal decomposition.

  According to the result of FIG. 3, in the electrode for electrolysis (Example 1) in which the porous layer having a continuous pore structure having a metal-organic functional group was formed, the electrolysis voltage was maintained at 4 V or less after 1000 hours. It was confirmed that electrolysis can be continued. On the other hand, it was found that the electrolysis voltage reached 5 V in the electrode for electrolysis (Comparative Example 1) on which tantalum oxide was formed, and the voltage increase was progressing. In addition, in the electrode for electrolysis (Comparative Example 2) formed with a porous layer having a continuous pore structure having a metal-organic functional group prepared by a thermal decomposition method, the electrolysis voltage is 7 V or more, and the electrode life is near. there were. After completion of the test, the results of surface observation and elemental analysis of the electrode for electrolysis in Comparative Example 1 and Comparative Example 2 showed that the scale composed of silicon dioxide and calcium was deposited and closed the continuous pores, so It was suggested that the rise was caused.

Claims (7)

A conductive substrate made of a valve metal;
An electrode for electrolysis having a platinum group metal and / or a catalyst layer containing an oxide thereof formed on the substrate,
An electrode for electrolysis, wherein a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond is formed on the catalyst layer.   2. The electrode for electrolysis according to claim 1, wherein the platinum group metal and / or its oxide is at least one selected from the group consisting of iridium oxide, platinum, platinum oxide and ruthenium oxide. .   The porous body layer having a continuous pore structure formed on the catalyst layer has a porosity in the range of 40 to 80%, an average pore diameter in the range of 0.01 to 20 μm, and a thickness. The electrode for electrolysis according to claim 1 or 2, wherein is in the range of 0.2 to 3 µm.   The electrode for electrolysis according to any one of claims 1 to 3, wherein the molecular weight of the organic functional group is 16 to 240.   The conductive substrate made of a valve metal is a substrate made of at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum and vanadium, or an alloy containing these metals as a main component. The electrode for electrolysis in any one of 1-4. In a method for producing an electrode for electrolysis comprising a conductive substrate made of a valve metal and a catalyst layer containing a platinum group metal and / or an oxide thereof formed on the substrate,
Next steps (1) to (3),
(1) a step of roughening the surface of a conductive substrate made of a valve metal;
(2) A dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, platinum, and ruthenium is dispersed or dissolved is applied onto a metal substrate, dried, fired, and thermally decomposed. Forming a catalyst layer comprising the platinum group metal and / or oxide thereof;
(3) An organometallic alkoxide having an alkoxy group in part is used as a starting material and is prepared by a chemical reaction using a hydrophilic organic solvent, and the metal compound, its partial hydrolysis, and / or its partial weight An organic / inorganic composite precursor solution containing the condensate in an organic solvent is applied, dried, and heat-treated to form a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond Forming an electrode surface layer formed,
Including
A method for producing an electrode for electrolysis, comprising forming a porous body layer having a continuous pore structure having a metal-organic functional group in a cross-linked structure by a metal-oxygen bond on the catalyst layer.   The metal in the organometallic alkoxide having a part of the alkoxy group is at least one metal selected from the group consisting of niobium, zirconium, titanium, tantalum, aluminum, and silicon. A method for producing an electrode for electrolysis.

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