JP2010095764A - Electrode for electrolysis and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tin dioxide electrode which can exhibit performance equal to that of a lead dioxide electrode as an electrode for electrolysis for decomposing organic matter in waste water by electrochemical reaction, so as to reduce COD (Chemical Oxygen Demand), an electrode for electrolysis for producing ozone and oxygen by electrolyzing water or an electrode for electrolysis used for producing perchlorates. <P>SOLUTION: Regarding the electrode for electrolysis in which the surface of a metal substrate is provided with an electrode surface layer formed in such a manner that tin oxide and antimony oxide are made into solid solution, the space between the metal substrate and the electrode surface layer is provided with an intermediate layer at least composed of a platinum group metal(s) or the oxide thereof as the main component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode for electrolysis used in an electrochemical chemical reaction. More specifically, the electrochemical reaction is used to decompose organic substances in reaction wastewater to reduce the chemical oxygen demand (COD). Electrolysis electrode to reduce, Electrolysis electrode to generate ozone and oxygen by electrolyzing water, Electrolysis electrode to preferentially generate oxygen by suppressing chlorine generation in seawater, Chloric acid The present invention relates to an electrode for electrolysis used for producing perchlorates.

  Conventionally, production of other oxidant raw materials such as perhalogenates such as sodium perchlorate, which are explosive raw materials, chlorates and iodates, generation of ozone by water electrolysis, organic synthesis or water treatment, etc. As an anode for industrial electrolysis, an electrode for electrolysis in which lead dioxide was electrodeposited on the surface of a titanium core was used.

  Lead dioxide is a compound with metal conductivity, lead itself has excellent durability, especially extremely stable during anodic polarization in an acidic bath, and can be manufactured relatively easily by electrodeposition. It has advantages and has been used extensively for many years.

  However, although the lead dioxide electrode has high durability, it is regarded as a problem that lead ions, which are harmful substances, are gradually consumed and dissolved in the electrolyte, and may be released to the natural world. . Also, in the process of manufacturing the lead dioxide electrode, there is a problem that this lead dioxide electrode has a large environmental load, such as a large amount of lead compounds being emitted as industrial waste. In recent years, an alternative electrode with a low environmental load has been required. ing.

  As an alternative electrode, Non-Patent Document 1 reports that a diamond electrode doped with boron has a very wide potential window and operates stably even in a highly corrosive aqueous solution. Further, Patent Document 1 and Patent Document 2 by Eastman Kodak Company suggest that organic compounds can be oxidatively decomposed using boron-doped diamond as an anode, and are expected as an alternative to lead dioxide electrodes. Further, Patent Document 3 proposes a method of generating ozone by performing water electrolysis with a porous conductive diamond electrode adjacent to a solid polymer electrolyte.

  As mentioned above, the conductive diamond electrode has been continuously researched and developed as an alternative to the lead dioxide electrode, but its manufacturing method is limited to the chemical vapor deposition method, its manufacturing equipment is complicated, Manufacturing electrodes of a size is very expensive and inferior in productivity. Furthermore, since it has the defect that welding and joining are not easy like the conventional metal electrode, it has not yet been put into practical use as an alternative electrode of the lead dioxide electrode.

  On the other hand, a tin dioxide electrode is known as an electrode for selectively decomposing organic substances. Non-Patent Document 2 discloses that in dye wastewater treatment, a sintered tin dioxide electrode has an extremely high oxygen overvoltage and is capable of selectively decomposing organic matter because of its high potential, which is superior to a lead dioxide electrode. It has been reported.

  Until now, attempts have been made to use a tin dioxide electrode as an alternative to a lead dioxide electrode. However, since tin dioxide itself is an n-type semiconductor, its conductivity is low, and as such, it cannot be used as an electrode for electrolysis. Can not. Therefore, a method is known in which the conductivity is increased by doping trivalent antimony into the crystal structure of tin dioxide and injecting holes to obtain an electrode for electrolysis.

  However, in the case of a bulk type tin dioxide electrode obtained by mixing the tin dioxide powder and the antimony trioxide powder described in Patent Document 2 and sintering under high temperature and high pressure, tin dioxide doped with antimony is used. Since its own resistance is much larger than that of metal, it is difficult to operate at an industrial high current density and is not practical. Therefore, a method of reducing the bulk resistance by reducing the film thickness to form an electrode for electrolysis, such as forming a tin dioxide thin film doped with antimony on a metal substrate which is a good conductor, can be considered. Many of the manufacturing methods are mainly chemical vapor deposition methods, but it is difficult to form a uniform film over a large area, and an alternative method is required because it is inferior in productivity and economy.

  In Patent Document 4, after preparing a coating solution containing tin oxide powder, antimony oxide powder, and platinum metal oxide obtained by coprecipitation, the coating solution is applied and doped with antimony and platinum group metal obtained by heat treatment. There has been proposed a tin dioxide electrode capable of obtaining a large current density by reducing the resistance of the electrode itself by forming the tin dioxide thin film layer.

  However, since the hydrolysis and polycondensation reaction rates of tin, antimony, and iridium compounds are different from each other, it is extremely difficult to adjust the target concentrations of tin, antimony, and iridium by the coprecipitation method. Then application is difficult. In addition, thin film formation using a coating solution prepared by a coprecipitation method has the disadvantage that it is easily made porous because it is composed of fine particles. When used as an electrode for electrolysis, the electrolytic solution is a metal substrate. The interface between the metal substrate and the electrode catalyst is destroyed in a short time, and the electrode life is short. As a method of solving this problem, a method of increasing the film thickness is also conceivable, but it is inferior in productivity and economy, and the resistance increases, so that the electrolytic voltage becomes high, so there is a problem as an electrode. Become.

  In addition, the resistance component appears to decrease as the electrode as a whole, but when viewed microscopically, platinum group metal oxides are scattered in the tin oxide, and the electrode surface is more resistant. Since a large amount of current flows through a low metal oxide, there is a problem that tin dioxide, which is an electrode active material for oxidizing and decomposing organic substances, cannot be effectively used. There has been a demand for a tin dioxide electrode that is sufficiently protected, can fully utilize the characteristics of the electrode active material, and can accommodate a large current density.

Japanese Patent Laid-Open No. 7-299467 US Pat. No. 5,399,247 JP-A-2005-336607 JP 2006-322056 A Fujishima et al., “Electrochemistry”, Vol. 67, (1999) 389 Nakajima et al., Electrochemistry and Industrial Physical Chemistry, Vol. 62, (1994) 1086

  Electrolysis electrodes for reducing the chemical oxygen demand (COD) by decomposing organic substances in the wastewater by electrochemical reaction, electrolysis electrodes for generating ozone and oxygen by electrolyzing water, An object of the present invention is to provide a tin dioxide electrode capable of exhibiting the same performance as a lead dioxide electrode as an electrode for electrolysis that can be suitably used for the production of chlorates.

  That is, the present invention is as follows.

The first invention is
On the surface of the metal substrate,
In an electrode for electrolysis comprising an electrode surface layer formed by solid solution of tin oxide and antimony oxide,
Between the metal substrate and the electrode surface layer,
An electrode for electrolysis having an intermediate layer containing at least a platinum group metal or an oxide thereof as a main component.

  The second invention is the electrode for electrolysis according to the first invention, wherein the solid solution ratio of antimony oxide to tin oxide in the electrode surface layer is 0.5 mol% or more and 10 mol% or less. is there.

  According to a third aspect of the invention, the platinum group metal is at least one platinum group metal selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum. It is an electrode for electrolysis.

  According to a fourth aspect of the present invention, there is provided an oxide layer of a Group 4 metal or a Group 5 metal between the intermediate layer and the metal substrate. This is an electrode for electrolysis.

  A fifth invention is the fourth invention, wherein the Group 4 metal or the Group 5 metal is at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum and vanadium. This is an electrode for electrolysis.

The sixth invention is:
Between the oxide layer and the intermediate layer,
The electrode for electrolysis according to the fourth or fifth invention, wherein the electrode has an oxide layer in which platinum group metal oxide crystal particles and a Group 4 metal or Group 5 metal oxide are mixed. .

In a seventh invention, the metal substrate is
Any one of the first to sixth inventions, characterized in that it is a metal 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. It is an electrode for electrolysis of description.

  The eighth invention is the electrode for electrolysis according to any one of the first to seventh inventions, characterized in that the use is an electrode for electrolysis for oxidizing and decomposing an organic substance.

  A ninth invention is the electrode for electrolysis according to any one of the first to seventh inventions, characterized in that the use is an electrode for electrolysis for generating ozone and / or oxygen by water electrolysis.

  The tenth invention is an electrode for electrolysis according to any one of the first to seventh inventions, characterized in that the use is an electrode for electrolysis for generating halogen acid ions and / or perhalogenate ions by electrolysis. Electrode.

An eleventh aspect of the invention is a method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on the surface of a metal substrate.
Next steps (1) to (2)
(1) A thermal decomposition method in which a dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum is dispersed or dissolved is applied onto a metal substrate, dried and fired. (2) Applying, drying and firing a dispersion medium in which a tin-containing compound and an antimony-containing compound are dispersed or dissolved to form tin oxide and antimony oxide. Is a method for producing an electrode for electrolysis including a step of forming an electrode surface layer in which the solid solution is dissolved.

A twelfth aspect of the invention is a method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on a surface layer of a metal substrate.
Next steps (1) to (3)
(1) A step of firing a metal substrate at 350 ° C. to 600 ° C. to form a metal oxide layer (2) A compound of at least one platinum group metal selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum A step of applying a dispersed or dissolved dispersion medium on a metal substrate, drying and firing, and forming an intermediate layer made of the platinum group metal oxide by a thermal decomposition method (3) A tin-containing compound and an antimony-containing compound This is a method for producing an electrode for electrolysis, which includes a step of applying, drying and firing a dispersed or dissolved dispersion medium to form an electrode surface layer in which tin oxide and antimony oxide are solid-dissolved.

A thirteenth aspect of the invention is a method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on a surface layer of a metal substrate.
Next steps (1) to (3)
(1) A dispersion medium in which a metal compound containing at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum and vanadium is dispersed or dissolved is applied onto a metal substrate, dried, fired, and metal oxidized. Step (2) for forming a physical layer: A dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum is dispersed or dissolved is applied onto a metal substrate, dried, A step of firing and forming an intermediate layer composed of the oxide of the platinum group metal by a thermal decomposition method (3) A dispersion medium in which a tin-containing compound and an antimony-containing compound are dispersed or dissolved is applied, dried, fired, and tin oxide And a method for producing an electrode for electrolysis including a step of forming an electrode surface layer in which antimony oxide is dissolved.

  According to the present invention, a group 4 metal and / or a group 5 oxide layer, a platinum group metal layer and / or an oxide layer thereof and a specific metal substrate and a tin dioxide electrode surface layer are provided. By forming the mixed layer, the adhesion and conductivity between the metal substrate and the tin dioxide electrode surface layer are greatly improved. Furthermore, by setting the thickness of the electrode surface layer to 20 μm or less, the resistance of the electrode for electrolysis is drastically reduced, and the entire surface of tin dioxide can effectively act as an electrode active material.

That is, the conductive metal oxide layer and the platinum group metal layer formed on the metal substrate and / or the oxide layer have excellent corrosion resistance and conductivity, and the conductive path between the tin dioxide layer and the metal substrate is good for a long period of time. Can be held and maintained.
The tin dioxide layer can increase the conductivity of the tin dioxide layer by containing 0.5 to 10 mol% of the antimony compound as an additive with respect to the tin compound. Furthermore, by making the tin dioxide layer in which antimony trioxide is dissolved into a thin film having a thickness of 20 μm or less, the electrode resistance is greatly reduced, and a large current density can be applied. In addition, the entire electrode surface functions as an electrode active material. Can be made.

  In the electrode for electrolysis of the present invention, the environment used is often a strongly acidic or oxidizing atmosphere, and in wastewater treatment etc., it may contain organic substances and fluorine compounds that accelerate the corrosion rate of metals and ceramics. Therefore, it is preferable that the metal substrate is at least one metal substrate selected from the group consisting of titanium, zirconium, niobium, tantalum, vanadium and alloys containing them as a main component. In order to reinforce the adhesion between the substrate and the surface layer of the tin dioxide electrode, it is preferable to use the surface of the metal substrate that has been subjected to blasting, etching, etc., surface area expansion and surface roughening in advance.

  After blasting or etching, the surface is selectively etched to clean and activate. 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.

  Next, a Group 4 metal oxide and / or a Group 5 metal oxide layer, which is a metal oxide layer, is preferably formed on the activated metal substrate surface by a firing method. When forming the metal oxide of the base metal, the base metal oxide layer can be formed on the surface of the base by firing the base metal in a gas containing an oxidizing gas, for example, in the air. . Moreover, it can form by the thermal decomposition method which is the method of apply | coating, drying, and baking the coating liquid which consists of a 4th and / or 5th group metal compound and the organic solvent which has a hydroxyl group.

  By the way, as a method of applying, drying, and baking a dispersion medium in which a Group 4 and / or Group 5 metal compound is dispersed or dissolved in an organic solvent having a hydroxyl group, a method using a sol-gel method or a coprecipitation method is also conceivable. However, the present invention is not suitable because the conductivity deteriorates. This is because an oxide layer manufactured by a sol-gel method or the like cannot form a highly conductive oxide layer because a metal-oxygen bond network is more complete.

  When forming a Group 4 metal oxide and / or Group 5 metal oxide layer, which is an oxide layer, by a thermal decomposition method, the metal substrate coated with the coating solution is applied at 50 to 100 ° C. for about 10 minutes. After drying, a Group 4 metal oxide and / or Group 5 metal oxide layer is formed by a thermal decomposition method in which heat treatment is performed at 350 ° C. or higher, more preferably in a range of 375 to 425 ° C.

  Examples of Group 4 and / or Group 5 metal compounds used in the coating solution include metal alkoxides, chlorides, acetates, and organometallic compounds. Specific examples include titanium (IV) ethoxide and titanium-iso-propoxide. , Titanium-n-butoxide, titanium (IV) -t-butoxide, titanium tetrachloride, titanium (IV) oxyacetylacetonate, bis (tert-butylcyclopentadienyl) titanium dichloride, zirconium (IV) ethoxide, zirconium tetra -N-butoxide, zirconium (IV) -t-butoxide, zirconium-iso-propoxide, zirconium (IV) chloride, tetrachlorobis (tetrahydrofuran) zirconium, bis (indenyl) zirconium dichloride, bis (cyclopentadioxide) Nyl) zirconium chloride hydride, bis (n-butylcyclopentadienyl) zirconium dichloride, bis (2-methylindenyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, pentamethylcyclopentadienyl zirconium trichloride , Vanadium (V) -triisopropoxide-oxide, vanadium (V) -t-tripropoxide, vanadium (V) -n-triboxide, vanadium oxide acetylacetonate, vanadium chloride, bis (cyclopentadienyl) vanadium Dichloride, dichloroethoxyoxovanadium (V), cyclopentadienyl vanadium tetracarbonyl, pentaisopropoxy niobium, pentaethoxy niobium, pentaethoxy niobium (V), Taethoxy niobium (V), niobium chloride (V), cyclopentadienyl niobium (V) -tetrachloride, niobium 2-ethylhexanoate (V), tetrachlorobis (tetrahydrofuran) niobium (IV), tetrakis (2, 2,6,6-tetramethyl-3,5-heptanedionato) niobium (IV), tantalum (V) ethoxide, tantalum (V) methoxide, tantalum (V) -2,2,2-trifluoroethoxide, tantalum ( V) butoxide, tantalum tetraethoxydimethylamino ethoxide, tantalum pentachloride, pentamethylcyclopentadienyl tantalum tetrachloride, tris (diethylamide) -t-butylimidotantalum, pentakis (dimethylamino) tantalum (V), pentamethylcyclo Pentadienyl tantalum tetrachloride, 2,4- Pentandionate tantalum (V) tetraethoxide, tetraethoxyacetylacetonato tantalum (V) and the like are mentioned. From the viewpoint of storage stability of the coating solution and economical viewpoint, the alkoxide or the chloride group 4 is preferable. It is preferable to use a Group 5 metal compound.

  Specific examples of the organic solvent having a hydroxyl group used in the coating solution include methanol, ethanol, propyl alcohol, isopropyl alcohol, butanol, pentanol, hexanol, and cyclohexanol, preferably propyl alcohol, isopropyl alcohol, butanol, Examples include pentanol.

  Formation of the Group 4 metal oxide and / or Group 5 metal oxide layer has the effect of improving the corrosion resistance, but the metal oxide also functions as a resistance component, and therefore, conductivity is particularly important. In this case, this step may be omitted. This is because an extremely thin metal oxide layer is formed on the outermost surface of the base metal when the intermediate layer is formed in the next step, and this oxide layer alone can sufficiently exhibit corrosion resistance.

  When the thickness of the Group 4 metal oxide and / or Group 5 metal oxide layer, which is the metal oxide layer, is less than 50 nm, the corrosion resistance cannot be sufficiently exerted, and when it exceeds 700 nm, the resistance becomes high. In view of deterioration of the conductive properties, 50 nm to 700 nm is preferable.

  Next, a platinum group metal layer and / or an oxide layer thereof as an intermediate layer is formed. The platinum group metal layer and / or its oxide layer can be formed by a method such as a thermal decomposition method or a sol-gel method, but is preferably formed by a thermal decomposition method.

  The component of the platinum group metal layer and / or its oxide layer is preferably a composition having at least one platinum group metal selected from iridium, ruthenium, rhodium, palladium and platinum, and an organometallic compound of each metal Alternatively, the coating solution is prepared by dissolving the metal chloride in an organic solvent having a hydroxyl group, for example, a solvent such as ethanol, propyl alcohol, or cyclohexanol.

  Further, when corrosion resistance is particularly required, the corrosion resistance may be improved by adding an organometallic compound or chloride of titanium, zirconium, tantalum, niobium, vanadium, tin to the coating solution. As a ratio to be added, it is preferable that the coating liquid is prepared so as to be 20 to 48 mol% for tantalum, vanadium and niobium, and 5 to 20 mol% for titanium, zirconium and tin.

  The coating method for forming the intermediate layer is not particularly limited and conventionally known methods can be used. For example, spray coating method, spraying method, curtain flow coating method, doctor blade method, dip coating method, brush coating method A spin coating method or the like can be used.

  After the metal substrate coated with the coating liquid is dried at 50 to 100 ° C. for about 10 minutes, the platinum group metal layer and / or its layer is subjected to a thermal decomposition method in which heat treatment is performed at 350 ° C. or higher, more preferably 380 to 550 ° C. An oxide layer is formed.

  In the above firing step, the platinum group metal layer and / or oxide crystal particles formed by heat treatment penetrate into the ultrathin insulating metal oxide formed on the outermost surface of the metal substrate by thermal diffusion. That is, a mixed layer in which a platinum group metal layer and / or oxide particles thereof are dispersed in a Group 4 metal oxide and / or a Group 5 metal oxide layer is formed, and the platinum group metal layer and / or Through the oxide particles, a conductive path is formed in the insulating metal oxide layer. As a result, good conductivity between the metal substrate and the platinum group metal layer and / or its oxide can be maintained.

  The platinum group metal layer and / or oxide layer thereof, and the mixed layer in which the platinum group metal layer and / or oxide particles thereof are dispersed in the metal oxide layer have a function of protecting the metal substrate. However, if the process from coating to thermal decomposition is repeated several times, the thickness of the platinum group metal layer can be increased, but a large number of cracks are likely to occur, and adhesion with the tin dioxide layer formed on the platinum group metal layer There is a risk that the performance will be greatly reduced. On the other hand, if the thickness is too thin, the protective function for the base metal is lowered. Therefore, the thickness is preferably in the range of 10 nm to 300 nm so that the electrical conductivity and the protective function of the base can be highly expressed. A range is more preferred.

  Next, a tin dioxide electrode surface layer is formed on the intermediate layer. An oxide layer of a base metal is mainly provided by providing an intermediate layer having a thickness of 10 nm to 300 nm. In this state, it is difficult to completely protect the base from the electrolyte solution, and the conductivity is also poor, generating ozone. Since the decomposition activity of organic substances and organic substances is low, it is difficult to function as an electrode for electrolysis as it is. Therefore, on the platinum group metal layer and / or its oxide layer, a tin dioxide layer having excellent conductivity and having a catalytic action for organic matter decomposition and ozone generation is formed by a thermal decomposition method.

  There are sputtering methods, ion plating methods, thermal decomposition methods, sol-gel methods, etc. as methods for forming the tin dioxide layer, but there is no need for complicated equipment, and thermal decomposition methods that can form even complex shapes uniformly. The method by the sol-gel method is preferable, but the thermal decomposition method that allows easier adjustment of the coating solution, better productivity, longer coating solution life, and formation of a more conductive thin film is most preferable.

  However, since tin dioxide alone is a semiconductor and has high resistance and it is difficult to function as an electrode for electrolysis, it is necessary to dope antimony trioxide having a different valence into the tin dioxide crystal. The doping amount of antimony trioxide is optimally doped so that the antimony trioxide / tin dioxide ratio is 0.5 mol% or more and 10 mol% or less from the viewpoint of conductivity, corrosion resistance, and catalytic action.

  The coating solution for forming the tin dioxide layer doped with antimony trioxide is 1.0 mol% or more and 40 mol with respect to the tin compound so that a tetragonal tin dioxide layer satisfying the above-described conditions can be formed. A coating solution is prepared by dissolving it in an organic solvent having a hydroxyl group so as to contain an antimony compound in an amount of% or less.

  Examples of tin compounds used in the coating liquid include metal alkoxides, chlorides, acetates, and organometallic compounds. Specific examples include tin (IV) -t-butoxide, tin (II) ethoxide, and tin (IV) isoform. Propoxide, tin (II) methoxide, tin (IV) -t-butoxide, tin (IV) -n-butoxide, diallyldibutyltin, bis (isooctylmaleic acid) dibutyltin, dibutyltin diacetate, bis (acetylacetonato) di N-butyltin, bis (trifluoromethanesulfonic acid) dibutyltin, dibutyltin diacetate, dibutyltin dichloride, dibutyltin dilaurate, dicyclohexyltin dibromide, dicyclohexyltin dibromide, diethylaminotrimethyltin, diethyltin trichloride, dimethyltin dilaurate, Dimethyl Phenyltin, dimethyltin dibromide, dimethyltin dichloride, bis (2-ethylhexanoic acid) di-n-butyltin, di-n-octyldichlorotin, dioctyltin oxide, diphenyltin dichloride, vinyltin dichloride, fenbutatin oxide, hexabutyl diphenyl Tin, hexamethyldistin, hexaphenyldistin, methyltin trichloride, phenyltin trichloride, stannic ammonium chloride, tetraallyltin, tetracyclohexyltin, tetra-n-propyltin, tetraphenyltin, triethyltin bromide, tribenzyl chloride Tin, tri-n-butyltin bromide, tributyltin chloride, tri-n-butyltin hydride, triethyltin chloride, trimethyltin bromide, trimethyltin chloride, tri-n-butyltin chloride, tri-n-butyl (trimethylsilyl) D Nyl) tin, tri-n-propyl tin acetate, tri-n-propyl tin chloride, triphenyl tin chloride, oleenyl tri-n-butyl tin, allyl tri-n-butyl tin, ammonium hexachlorotin (IV), bis (acetoxydimethyltin) oxide Bis (trimethyltin) acetylene, bis (triphenyltin) oxide, n-butyltin trichloride, cis-tri-n-butyl (1-propenyl) tin, bis (2,4-pentanedioic acid) dibutyltin, dibutyltin oxide , Dibutyltin maleate, dichlorodiphenyltin, dimethyltin oxide, di-n-butyltin diacetate, di-n-butyltin dichloride, di-n-butyltin dilaurate, di-n-butyltin oxide, di-n-butyltin bis (Acetylacetate Natto), di-n-butyltin bis (2-ethylhexanoate, di-n-octyltin oxide, diphenyltin oxide, di-t-butyltin dichloride, vinyltin dichloride, ethynyltri-n-butyltin, fenbutane oxide, hexabutyl Distin, hexa-n-butyldistin, methallyltri-n-butyltin, methyltin trichloride, tri-n-butyltin trichloride, phenyltin trichloride-1-propynyltri-n-butyltin, stannic chloride pentahydrate , Stannous chloride dihydrate, tetraethyltin, tetra-iso-propyltin, tetramethyltin, tetra-n-butylammonium difluorotriphenyltin, tetraphenyltin, tetravinyltin (IV), tin (IV) acetate , Tin (IV) bromide, tin (IV) chloride, bis 2,4-pentanedioic acid) tin (IV) chloride, tin (IV) fluoride, tin (IV) iodide, trans-1,2-bis (tri-n-butyltin) ethylene, tri-n-butyl ( 3-methyl-2-butenyl) tin, tri-n-butyltin acetate, tri-n-butyl (vinyl) tin, tin (IV) 2-ethylhexanoate, tri-n-propyltin acetate, tri-n-propyltin chloride , Triphenyltin acetate (IV), triphenyltin chloride, triphenyltin fluoride, etc., but from the viewpoint of coating solution storage stability and environmental impact, a tin compound that is preferably a halide such as tin chloride is used. It is preferred to use.

  Antimony compounds to be added to the coating solution for forming the tin dioxide layer include metal alkoxides, chlorides, acetates, and organometallic compounds. Specific examples include antimony (III) butoxide, antimony (III ) Ethoxide, antimony (III) isopropoxide, antimony (III) methoxide, antimony pentafluoride, antimony tri-n-butyl, antimony tri-α-naphthyl, antimony oxalate, antimony triiodide, triphenylantimony, tetra Ammonium (III) fluoroantimonate, antimony (III) acetate, antimony (III) bromide, antimony (III) chloride, antimony (III) fluoride, antimony (III) iodide, hexafluoroantimonic acid hexahydrate, Hexafluo Examples include antimonic acid-1-n-butyl-3-methylimidazolium, triphenylantimony, triphenylantimony dibromide, tris (dimethylamino) antimony, etc., but coating solution storage stability, environmental load, economical From the viewpoint, it is preferable to use an antimony compound which is preferably an alkoxide or a chloride.

  Specific examples of the organic solvent having a hydroxyl group used in the coating solution include methanol, ethanol, propyl alcohol, isopropyl alcohol, butanol, pentanol, hexanol, and cyclohexanol, preferably propyl alcohol, isopropyl alcohol, butanol, Examples include pentanol.

  The coating method for forming the tetragonal tin dioxide layer doped with antimony trioxide is not particularly limited, and any conventionally known coating method can be used. For example, spray coating method, spraying method, curtain flow coating method A doctor blade method, a dip coating method, a brush coating method, a spin coating method, or the like can be used.

  In order to form a tetragonal tin dioxide layer doped with antimony trioxide by a thermal decomposition method, the coating solution was applied on the metal substrate on which the intermediate layer was formed, and then dried at 50 to 100 ° C. for about 10 minutes. Thereafter, a tin dioxide layer which is an electrode surface layer is formed by a thermal decomposition method in which heat treatment is performed in a temperature range of 475 to 550 ° C., more preferably from 450 ° C. to 600 ° C. from the viewpoint of corrosion resistance and conductivity.

  The above-described operations of applying and drying the coating solution and performing heat treatment for thermal decomposition are repeated until a tin dioxide layer doped with antimony trioxide having a desired thickness is obtained. If the thickness of the tin dioxide layer to be formed is less than 0.2 μm, pinholes and cracks are likely to occur, which is insufficient to protect the metal substrate from the electrolytic solution, and the platinum group metal layer which is an intermediate layer and / or There is a possibility that the oxide reaches the surface of the tin dioxide layer by thermal diffusion and greatly reduces the electrocatalytic activity. On the other hand, when the thickness is 20 μm or more, the resistance of the tin dioxide layer itself is increased, and the electrolytic voltage becomes abnormally high, making it difficult to function as an electrode. Therefore, the range of 0.2 μm to 20 μm is preferable. To 0.75 μm to 5 μm is more preferable.

  In addition, an intermediate layer composed of a platinum group metal layer and / or its oxide layer is formed on the metal substrate in advance after bending such as pressing, cutting, etching, etc., and then antimony trioxide is formed on the upper layer. By forming a doped tin dioxide layer, the catalytic activity of the tin dioxide, the substrate protection function by the intermediate layer, and high conductivity can be reliably obtained without damaging the tin dioxide layer even when forming a substrate having a complicated shape. be able to. For example, regarding the formation of a tin dioxide layer, if the intermediate layer and the tin dioxide layer are sequentially formed on the substrate after processing as described above, even if the substrate surface is uneven due to processing, each layer is uniformly formed. Can be formed, and stable electrode performance can be obtained.

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

Example 1
Mixing 2.53 g of tin tetrachloride, 0.18 g of antimony pentachloride, 98 ml of butanol, and 2 ml of cyclohexanol, and maintaining at 5 ° C., stirring for 1 hour under a nitrogen atmosphere, thereby containing dioxide containing 3 mol% of antimony trioxide. A tin-forming coating solution was prepared.

  A Ti substrate (JIS type 2) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 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.

An intermediate layer coating solution was prepared by mixing 3.52 g of iridium trichloride trihydrate, 98 ml of ethanol, and 2 ml of cyclohexanol, and stirring for 8 hours in a nitrogen atmosphere. After applying the surface treatment process to the Ti substrate by the brush coating method, heat treatment is performed at 490 ° C. for 1 hour to form an IrO ₂ layer having a thickness of 50 nm and a TiO ₂ layer (about 100 nm) in which a conductive path is formed. Then, the intermediate layer forming step was completed.

  The step of applying a tin dioxide-forming coating solution containing 3 mol% of antimony trioxide on the Ti substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 525 ° C. for 1 hour in air is repeated 10 times. Thus, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 3 mol% of antimony trioxide having a thickness of 2.5 μm was formed.

(Example 2)
Mixing 3.91 g of tin (IV) butoxide, 0.34 g of antimony (III) butoxide, 98 ml of butanol, 2 ml of cyclohexanol and maintaining at 5 ° C., stirring for 1 hour under a nitrogen atmosphere, 5 mol of antimony trioxide %, A tin dioxide-forming coating solution was prepared.

  A Ti substrate (JIS type 2) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 mm. The satin finish was performed by etching the substrate for 8 hours in a 10 wt% oxalic acid aqueous solution. 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.

Zirconium tetra-n-butoxide (3.83 g), butanol (95 ml), and acetylacetone (5 ml) were mixed, stirred for 8 hours in a nitrogen atmosphere, concentrated, diluted with ethanol, and adjusted to a concentration of 0.005M. Got ready. A ZrO ₂ layer having a thickness of 230 nm was formed by applying a heat treatment at 400 ° C. for 1 hour after applying the surface treatment process on the Ti substrate by the dip method.

An intermediate layer coating solution was prepared by mixing 1.06 g of iridium trichloride trihydrate, 5.68 g of tantalum (V) ethoxide, 98 ml of isopropanol, and 2 ml of cyclohexanol, and stirring for 8 hours in a nitrogen atmosphere. After coating the De'ipu method on Ti substrate forming the ZrO ₂ layer, by performing a heat treatment for 1 hour at 500 ° C., _ZrO 2 / TiO _{of IrO} 2 _-Ta 2 _{O 5} layer and the conductive paths of thickness 110nm was formed _Two layers were formed, and the intermediate layer forming step was completed.

  The step of applying a tin dioxide-forming coating solution containing 5 mol% of antimony trioxide on the Ti substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 500 ° C. for 1 hour in air is repeated 10 times. Thus, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 5 mol% of antimony trioxide having a thickness of 2.1 μm was formed.

(Example 3)
Stir in an argon atmosphere for 1 hour while mixing 5.04 g of tin (II) 2-ethylhexanoate, 0.51 g of antimony (V) 2-ethylhexanoate, 98 ml of butanol and 2 ml of cyclohexanol and keeping at 5 ° C. Thus, a tin dioxide forming coating solution containing 3 mol% of antimony trioxide was prepared.

  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 0.2 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 immersion in 6N hydrofluoric acid for 1 minute, and the Nb substrate surface treatment step was completed.

The intermediate layer coating solution was prepared by mixing 2.61 g of ruthenium trichloride trihydrate, 98 ml of ethanol, and 2 ml of cyclohexanol, and stirring for 8 hours in a nitrogen atmosphere. After applying the surface treatment process to the Nb substrate by brush coating, heat treatment is performed at 475 ° C. for 1 hour to form a RuO ₂ layer having a thickness of 50 nm and an NbO ₂ layer (about 120 nm) in which a conductive path is formed. Then, the intermediate layer forming step was completed.

  The step of applying a tin dioxide forming coating solution containing 3 mol% of antimony trioxide on the Nb substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 500 ° C. in air for 1 hour is repeated 10 times. Thus, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 3 mol% of antimony trioxide having a thickness of 2.3 μm was formed.

Example 4
By stirring for 1 hour under an argon atmosphere while mixing 3.94 g of tin (IV) isopropoxide, 0.42 g of triphenylantimony dichloride, 90 ml of isopropyl alcohol, 8 ml of acetylacetone and 2 ml of butanol and maintaining at 5 ° C., A coating solution for forming tin dioxide containing 5 mol% of antimony trioxide was prepared.

  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 0.2 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 immersion in 6N hydrofluoric acid for 1 minute, and the Nb substrate surface treatment step was completed.

A NbO ₂ layer having a thickness of 225 nm was formed by heat-treating the Nb substrate after the surface treatment step in air at 400 ° C. for 1 hour.

An intermediate layer coating solution was prepared by mixing 2.09 g of ruthenium trichloride trihydrate, 0.64 g of niobium (V) ethoxide, 90 ml of ethanol, and 10 ml of acetylacetone and stirring for 8 hours in a nitrogen atmosphere. After the surface treatment process is applied on the Nb substrate by the dip method, a heat treatment is performed at 500 ° C. for 1 hour to form a RuO ₂ layer having a thickness of 75 nm and an NbO ₂ layer in which a conductive path is formed. The forming process is finished.

  The step of applying a tin dioxide-forming coating solution containing 5 mol% of antimony trioxide on the Nb substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 500 ° C. for 1 hour in air is repeated 10 times. Thus, a total of ten electrodes for electrolysis were formed on which a tin dioxide film containing 5 mol% of antimony trioxide having a thickness of 2.4 μm was formed.

(Example 5)
Dioctyltin oxide (IV) 3.50 g, antimony pentafluoride (V) 0.13 g, butanol 98 ml, cyclohexanol 2 ml were mixed and kept at 5 ° C., and the mixture was stirred for 1 hour in an argon atmosphere to obtain trioxide. A coating solution for forming tin dioxide containing 3 mol% of antimony was prepared.

  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 0.2 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 immersion in 6N hydrofluoric acid for 1 minute, and the Zr substrate surface treatment step was completed.

Titanium tetra-n-butoxide (3.40 g), butanol (95 ml), and acetylacetone (5 ml) were mixed, stirred for 8 hours in a nitrogen atmosphere, concentrated, diluted with butanol to adjust the concentration to 0.005 M, and the intermediate layer coating solution was prepared. Got ready. A TiO ₂ layer having a thickness of 310 nm was formed by applying a heat treatment at 400 ° C. for 1 hour after applying the surface treatment process on the Zr substrate by the dip method.

Rhodium trichloride trihydrate (2.11 g), zirconium tetra-n-butoxide (0.77 g), ethanol (50 ml), butanol (45 ml), cyclohexanol (2 ml), and acetylacetone (3 ml) are mixed and stirred for 8 hours in a nitrogen atmosphere for an intermediate layer. The coating solution was adjusted. After applying the brush coating method on the Zr substrate on which the TiO ₂ layer is formed, a heat treatment is performed at 500 ° C. for 1 hour, so that the Rh ₂ O ₃ —ZrO ₂ layer having a thickness of 150 nm and the conductive path formed in TiO ₂ / A ZrO ₂ layer was formed, and the intermediate layer forming step was completed.

  The step of applying a tin dioxide-forming coating solution containing 3 mol% of antimony trioxide on the Zr substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 450 ° C. in air for 10 minutes is repeated 10 times. Thus, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 3 mol% of antimony trioxide having a thickness of 2.1 μm was formed.

(Example 6)
Mixing tributyltin chloride (IV) 3.10 g, antimony (III) ethoxide 0.26 g, butanol 90 ml, acetylacetone 8 ml, cyclohexanol 2 ml, and maintaining at 5 ° C., stirring for 3 hours under an argon atmosphere for trioxide A coating solution for forming tin dioxide containing 5 mol% of antimony 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 0.2 mm. The base was finished by shot blasting using silicon carbide. Next, after degreasing treatment with an organic solvent, the oxide film was removed by immersion in 6N hydrofluoric acid for 1 minute, and the Ta substrate surface treatment step was completed.

The Ta substrate having finished the surface treatment process was heat-treated in air at 525 ° C. for 1 hour to form a Ta ₂ O ₅ layer having a thickness of 115 nm.

Palladium (II) acetylacetonate 1.37 g, platinum (IV) chloride hexahydrate 2.33 g, anhydrous tin tetrachloride 0.26 g, toluene 45 ml, butanol 45 ml, ethanol 5 ml, pure water 5 ml were mixed and mixed with nitrogen. The intermediate layer coating solution was prepared by stirring for 8 hours under an atmosphere. After coating the De'ipu method on Ta substrate to form a Ta ₂ O ₅ layer, by performing a heat treatment for 1 hour at 500 ° C., _Ta 2 the Pd-Pt-SnO ₂ layer and the conductive path in the thickness 130nm was formed O _Five layers were formed, and the intermediate layer forming step was completed.

  The step of applying a tin dioxide-forming coating solution containing 5 mol% of antimony trioxide on the Ta substrate that has completed the intermediate layer forming step by dipping and performing a heat treatment at 450 ° C. for 30 minutes in air is repeated 13 times. Thus, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 5 mol% of antimony trioxide having a thickness of 2.5 μm was formed.

(Example 7)
By stirring for 1 hour under an argon atmosphere while mixing 4.08 g of tin (IV) bromide, 0.42 g of antimony pentachloride, 98 ml of butanol and 2 ml of hexanol and maintaining at 5 ° C., 7 mol% of antimony trioxide was obtained. The coating solution for forming tin dioxide was prepared.

  A vanadium substrate was used as the metal substrate. The vanadium substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.2 mm. The base was finished by shot blasting using silicon carbide. 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 vanadium substrate surface treatment step was completed.

The intermediate layer coating solution was prepared by mixing tantalum (V) -n-butoxide 5.47 g, butanol 97 ml, and acetylacetone 3 ml, and stirring for 8 hours in a nitrogen atmosphere. A 400 nm thick Ta ₂ O ₅ layer was formed by applying a heat treatment at 520 ° C. for 1 hour after coating on the vanadium substrate after the surface treatment step.

The intermediate layer coating solution was prepared by mixing 5.18 g of chloroplatinic acid hexahydrate and 100 ml of butanol and stirring for 8 hours under a nitrogen atmosphere. After coating the Ta ₂ O ₅ layer brushing method on vanadium substrate formed, and in the heat treatment of 1 hour at 500 ° C., _Ta Pt layer and a conductive path in the thickness 150nm was formed _{2 O} 5 / _V 2 An O ₅ layer was formed to complete the intermediate layer forming step.

  The step of applying a tin dioxide-forming coating solution containing 7 mol% of antimony trioxide on the vanadium substrate that has completed the intermediate layer forming step by a brush coating method and performing a heat treatment at 525 ° C. for 2 hours in air is repeated 10 times. Thus, a total of ten electrodes for electrolysis were formed on which a tin dioxide film containing 7 mol% of antimony trioxide having a thickness of 2.6 μm was formed.

(Comparative Example 1)
A Ti substrate (JIS type 2) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 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.

The intermediate layer coating solution was prepared by mixing 5.18 g of chloroplatinic acid hexahydrate and 100 ml of butanol and stirring for 8 hours under a nitrogen atmosphere. The surface treatment process on finished Ti substrate by performing heat treatment for 1 hour at 475 ° C. in air to form the TiO ₂ layer of thickness 150 nm. Next, an intermediate layer coating solution is applied to the Ti substrate on which the TiO ₂ layer is formed by brush coating, and heat treatment is performed at 490 ° C. for 1 hour in an ammonia gas atmosphere, thereby forming a Pt layer having a thickness of 50 nm. Then, the intermediate layer forming step was completed.

Electrolysis was carried out for 2 hours at a current density of 1 A / dm ² in an electrolytic bath at 40 ° C. in which Rissurge (PbO) was saturated in 25 wt% sodium hydroxide, and an α-lead dioxide layer was formed on the surface. Next, electrolysis was performed for 8 hours at a current density of ² A / dm ^{2 using} an 800 g / liter lead nitrate aqueous solution as an electrolyte and a core material formed with an α-lead dioxide layer as an anode to form a 20 μm-thick β-lead dioxide layer. A total of 10 electrolysis electrodes were produced.

(Comparative Example 2)
In Example 1, the same procedure was carried out except that the intermediate layer forming step was omitted, and a total of 10 electrodes for electrolysis were formed on which a tin dioxide film containing 3 mol% of antimony trioxide having a thickness of 2.4 μm was formed.

(Comparative Example 3)
According to the method described in Patent Document 4, an electrode for electrolysis was produced. Specifically, antimony pentachloride is added to tin butanol solution of tetrabutoxytin so that (Sb / Sn) mol% is 5 mol%, and further 5 mol% to (Sn + Sb). Of iridium trichloride (IrCl ₃ / nH ₂ O) was added and dissolved while heating to prepare a translucent tin dioxide forming coating solution in which a Tyndall phenomenon was observed.

  A Ti substrate (JIS type 2) was used as the metal substrate. The Ti substrate is a rolled material having a size of 20 × 30 mm and a thickness of 0.5 mm. The substrate was pickled with 90% 25% sulfuric acid for 1 hour, and the Ti substrate surface treatment step was completed.

A coating solution for an intermediate layer was prepared by mixing 2.38 g of titanium-n-butoxide, 3.28 g of tantalum (V) -n-butoxide, and 100 ml of butanol and stirring for 8 hours in a nitrogen atmosphere. A TiO ₂ —Ta ₂ O ₅ layer having a thickness of 200 nm was formed by applying a heat treatment at 500 ° C. for 1 hour after coating on the Ti substrate after the surface treatment process.

  A translucent tin dioxide-forming coating solution is applied with a brush on the Ti substrate that has been subjected to the intermediate layer treatment step, dried at 120 ° C. for 10 minutes, and then heat-treated at 490 ° C. in air for 10 minutes. By repeating the process twelve times, a total of 10 electrodes for electrolysis were formed on which a tin dioxide film having a thickness of 2.3 μm and containing 1.2 mol% of antimony trioxide and 2.4 mol% of iridium dioxide was formed.

For the electrolysis electrode according to the present invention thus prepared and the comparative example, an aqueous solution containing sodium sulfate 50 g / L and methylene blue 1000 ppm was used as the supporting electrolyte, the electrolysis electrode was used as the anode, the platinum electrode was used as the cathode, and the reference electrode A silver / silver chloride electrode was used, and an oxidative degradation test was carried out for 10 hours using a triode constant current electrolysis of methylene blue under the conditions of a current density of 20 A / dm ² and an electrolyte temperature of 25 ° C. Table 1 shows the results of comparing the methylene blue concentrations after 10 hours. Table 2 shows the potential (vs silver / silver-silver chloride electrode) after 5 hours of electrolytic oxidation decomposition test.

Next, with respect to the produced electrode for electrolysis according to the present invention and the comparative example, 250 g / L of sulfuric acid as a supporting electrolyte and 100 ppm of 2,2,3,3-tetrafluoropropyl alcohol used as a smoothing agent for metal plating are included. Using an aqueous solution, an electrode for electrolysis as the anode, a platinum electrode as the cathode, a silver / silver chloride electrode as the reference electrode, a current density of 20 A / dm ² , and an electrolyte temperature of 25 ° C., an electrode life test was conducted for 1000 hours Table 2 shows the results of comparing the potentials after 500 hours and 1000 hours. Further, after the electrode life test was completed, the film thickness for each electrode was measured by a fluorescent X-ray film thickness measurement method, and the results of calculating the residual ratio were also shown in Table 2.

(Evaluation as sodium perchlorate production electrode)
Using the prepared electrodes for electrolysis of Examples 2 and 4, Comparative Example 1 and Example 3, sodium perchlorate was produced by a diaphragm electrolysis method. 600 g / L sodium chlorate 250 ml as anolyte electrolyte, 100 g / L sulfuric acid 250 ml as cathode electrolyte, and each electrolyte temperature is maintained at 35 ° C. or lower, and each electrode is used as an electrode for electrolysis and platinum as a cathode. Table 3 shows the time required for electrolysis and the current efficiency calculated from the time required for electrolysis when electrolysis was performed until the chloric acid concentration reached 0 g / L under the condition of a density of 40 A / dm2.

(Evaluation as an ozone generating electrode)
Using the produced electrode for electrolysis according to the present invention and the electrode of the comparative example, the ability as an electrode for ozone generation was compared. First, using a Ti and Nb porous sintered body (φ50 mm, thickness 1 mm) as a metal substrate, an electrode for electrolysis in which a tin dioxide film was formed was prepared according to the method described in Example 2 and Example 4. Similarly, Ti was used as the metal substrate, and the electrodes for electrolysis were prepared according to the methods described in Comparative Examples 1 and 3. In a solid electrolyte electrolyte layer made of PTFE, a stainless sintered porous electrode (φ50 mm, thickness 1 mm) is incorporated in the cathode, each electrode produced according to the example and the comparative example is incorporated in the anode, and the temperature is 25 in the anode chamber. Electrolysis was carried out for 1000 hours under conditions of 100 A / dm 2 while circulating ultrapure water maintained at ° C. At that time, ozone gas generated in the anode chamber was passed through a potassium iodide solution for a certain period of time to make it acidic with sulfuric acid, and then the ozone concentration was determined by an indirect titration method using a 0.1N sodium thiosulfate standard solution. The change in ozone concentration with respect to time is shown in FIG.

  Subsequently, with respect to the coating solution for the electrode for electrolysis according to the present invention and the coating solution manufactured in Comparative Example 3, each coating solution was placed in a glass storage bottle with a polypropylene lid, and the gas phase portion was replaced with argon gas. The container was later sealed and stored in an air circulation dryer maintained at 60 ° C. for 1 month. Then, it took out from the dryer, the state of the coating liquid was confirmed visually, and the result of having investigated about the liquid life of the coating liquid was shown in FIG.

(Result, discussion)
According to the results in Table 1, when electrolysis was performed using the electrode for electrolysis according to the present invention, the electrolysis progressed at a high potential of about 2000 mV (vsAg / AgCl), but the methylene blue remaining in the electrolyte solution remained. It was recognized that only 25 ppm or less remained and the performance was almost the same as that of the conventional electrode (Comparative Example 1). Further, it was confirmed that the same result was obtained in Comparative Example 2 in which the intermediate layer was not formed in Example 1. In contrast, in Comparative Example 3 in which iridium dioxide was added to the tin dioxide electrode layer in order to reduce the potential, electrolysis proceeds at a relatively low potential (1800 mV or less), but the residual methylene blue concentration is high. Thus, it was confirmed that the electrolytic oxidation ability was low as compared with the conventional electrode and the electrode for electrolysis according to the present invention.

  According to the results of Table 2, when electrolysis was performed using the electrode for electrolysis according to the present invention, the potential remained at 3000 mV (vsAg / AgCl) or less after 1000 hours, and the tin dioxide film thickness remained. Since the rate is also 50% or more, the platinum group metal layer provided by the present invention and / or the intermediate layer composed of the oxide layer thereof against the attack on the substrate interface by the leveling agent or acid. It was shown that it was protected and was an electrode for electrolysis excellent in corrosion resistance. On the other hand, in Comparative Example 2, since the intermediate layer was not provided, the interface was destroyed and part of the surface of the tin dioxide began to peel off, and the potential was abnormally high at 6000 mV or more. The residual thickness ratio of the film was also less than 50%, confirming poor corrosion resistance. Also in Comparative Example 3, peeling was observed on a part of the tin dioxide surface, the potential was abnormally high at 6000 mV or more, and the thickness residual rate of the tin dioxide film was very low at 13%, which may be inferior in corrosion resistance. confirmed.

  According to the results of Table 3, when electrolysis was performed using the electrode for electrolysis according to the present invention, the electrolysis time was within 100 hours, the current efficiency was 34% or more, and the existing electrode of Comparative Example 1 was It was shown to have inferior electrolytic oxidation performance. In contrast, the electrode of Comparative Example 3 had an electrolysis time of 150 hours or longer, a current efficiency of 20% or less, and it was confirmed that the electrolytic oxidation performance was poor.

  According to the result of FIG. 1, when electrolysis is performed using the electrode for electrolysis according to the present invention, the electrolysis is maintained at 9% or more after 1000 hours of electrolysis, which is comparable to that of Comparative Example 1 which is an existing electrode. It was shown to have oxidation performance. On the other hand, in Comparative Example 3, the ozone generation efficiency was only about 6% even after 1000 hours had elapsed from the electrolysis initial stage, and it was confirmed that the electrooxidation performance was poor.

  According to the results in Table 4, the coating solution for the electrode for electrolysis used in the present invention does not undergo hydrolysis or polycondensation reaction even after a 1 month storage test at 60 ° C., and has a transparent state. It was confirmed that it was excellent in storage stability. On the other hand, the coating solution prepared in Comparative Example 3 changed to a cloudy translucent liquid at the end of the storage test, and a white precipitate that appeared to be generated by hydrolysis and polycondensation reaction at the bottom of the storage bottle. A thing was seen and it was confirmed that it lacks storage stability.

  The electrode for electrolysis of the present invention reduces the chemical oxygen demand (COD) in wastewater by electrochemical oxidation, generates ozone and oxygen by electrolysis of water, and produces chloric acids and perchlorates. Therefore, the electrode is mainly used. It can also be suitably used as a corrosion-resistant conductive coating material.

The graph which shows the change of the ozone concentration with respect to the electrolysis time at the time of producing | generating ozone using the electrode for electrolysis produced in the Example and the comparative example.

Claims (13)

On the surface of the metal substrate,
In an electrode for electrolysis comprising an electrode surface layer formed by solid solution of tin oxide and antimony oxide,
Between the metal substrate and the electrode surface layer,
An electrode for electrolysis comprising an intermediate layer containing at least a platinum group metal or an oxide thereof as a main component.   The electrode for electrolysis according to claim 1, wherein the solid solution ratio of antimony oxide to tin oxide in the electrode surface layer is 0.5 mol% or more and 10 mol% or less.   The electrode for electrolysis according to claim 1 or 2, wherein the platinum group metal is at least one platinum group metal selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum.   The electrode for electrolysis according to any one of claims 1 to 3, further comprising an oxide layer of a Group 4 metal or a Group 5 metal between the intermediate layer and the metal substrate.   The electrode for electrolysis according to claim 4, wherein the Group 4 metal or the Group 5 metal is at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum, and vanadium. Between the oxide layer and the intermediate layer,
6. The electrode for electrolysis according to claim 4, wherein the electrode has an oxide layer in which platinum group metal oxide crystal particles and a Group 4 metal or Group 5 metal oxide are mixed. The metal substrate is
7. A metal 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. Electrolysis electrode.   The electrode for electrolysis according to any one of claims 1 to 7, wherein the use is an electrode for electrolysis for oxidizing and decomposing an organic substance.   The electrode for electrolysis according to any one of claims 1 to 7, wherein the use is an electrode for electrolysis for generating ozone and / or oxygen by water electrolysis.   The electrode for electrolysis according to any one of claims 1 to 7, wherein the use is an electrode for electrolysis for generating a halogenate ion and / or a perhalogenate ion by electrolysis. In the method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on the surface of a metal substrate,
Next steps (1) to (2)
(1) A thermal decomposition method in which a dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum is dispersed or dissolved is applied onto a metal substrate, dried and fired. (2) Applying, drying and firing a dispersion medium in which a tin-containing compound and an antimony-containing compound are dispersed or dissolved to form tin oxide and antimony oxide. The manufacturing method of the electrode for electrolysis including the process of forming the electrode surface layer in which and dissolved. In the method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on the surface layer of the metal substrate,
Next steps (1) to (3)
(1) A step of firing a metal substrate at 350 ° C. to 600 ° C. to form a metal oxide layer (2) A compound of at least one platinum group metal selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum (3) A step of forming a tin-containing compound and an antimony-containing compound by applying a dispersed or dissolved dispersion medium on a metal substrate, drying and firing, and forming an intermediate layer made of the oxide of the platinum group metal by a thermal decomposition method. A method for producing an electrode for electrolysis comprising a step of applying, drying and firing a dispersion medium dissolved or dissolved to form an electrode surface layer in which tin oxide and antimony oxide are solid-dissolved. In the method for producing an electrode for electrolysis having an electrode surface layer formed by solid solution of tin oxide and antimony oxide on the surface layer of the metal substrate,
Next steps (1) to (3)
(1) A dispersion medium in which a metal compound containing at least one metal selected from the group consisting of titanium, zirconium, niobium, tantalum and vanadium is dispersed or dissolved is applied onto a metal substrate, dried, fired, and metal oxidized. Step (2) for forming a physical layer: A dispersion medium in which at least one platinum group metal compound selected from the group consisting of iridium, ruthenium, rhodium, palladium and platinum is dispersed or dissolved is applied onto a metal substrate, dried, A step of firing and forming an intermediate layer composed of the oxide of the platinum group metal by a thermal decomposition method (3) A dispersion medium in which a tin-containing compound and an antimony-containing compound are dispersed or dissolved is applied, dried, fired, and tin oxide And a method for producing an electrode for electrolysis, comprising a step of forming an electrode surface layer in which antimony oxide is dissolved.

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