JPH07331494A - Oxygen generating electrode and its production - Google Patents

Abstract

PURPOSE:To provide an oxygen generating electrode excellent in durability and having a longer service life than the conventional insoluble electrode. CONSTITUTION:This oxygen generating electrode has a substrate 1 with at least the surface consisting of elemental titanium or titanium alloy, a layer 2 formed on the substrate 1 surface and consisting of titanium oxide alone, at least one intermediate layer 3 formed on the layer 2 surface, consisting essentially of the oxides of elements other than platinum-group elements and contg. a mixture of the oxide and oxides of platinum-group elements and a catalyst layer 4 formed on the layer 3 and consisting essentially of the mixed oxide consisting essentially of the oxides of platinum-group elements, Besides, the electrode may have a layer of oxides alone consisting essentially of the oxides of the elements other than the platinum-group elements and titanium between the layers 2 and 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for oxygen generation used in the electrochemical industry and a method for producing the same, more specifically, it is an anode in the electrolytic industry such as electroplating, electrolytic refining, organic electrolytic synthesis and cathodic protection. The present invention relates to an electrode for generating insoluble oxygen that exhibits excellent durability when used as a material and a method for producing the same.

[0002]

In the electrolysis industry, for example, zinc,
When plating copper, chromium, etc., for example, iron, copper, titanium, stainless steel in a plating bath containing zinc sulfate, copper sulfate, chromium sulfate, etc. The electrolytic reaction proceeds in a state in which a substrate made of, for example, is immersed as a cathode, and an electrode for oxygen generation by energization is immersed as an anode. As the oxygen generating electrode at this time, a lead electrode has been widely used. Not only can this lead electrode be manufactured at a low cost, but even if lead dissolves in the plating bath, the solubility of lead in sulfuric acid is small, and the lead concentration in the plating bath can be maintained at a low level. It has the advantage that the plated surface is less susceptible to lead ions.

However, when this lead electrode is used as an oxygen generating electrode, the overvoltage during oxygen generation becomes high, and the distance between both electrodes becomes wide due to the dissolution of lead due to the progress of electrolysis. There is a problem that the overall electrolysis voltage rises. That is, it becomes difficult to reduce power consumption during energization, and moreover, the frequency of electrode replacement increases with adjustment between electrodes and thinning of electrodes.

Instead of the lead electrode having such a defect,
An insoluble electrode whose surface is coated with a noble metal alone or a noble metal oxide is often used as an oxygen generating electrode. This insoluble electrode is usually formed by oxidizing a surface of a base material made of a valve metal such as titanium or an alloy containing the valve metal as a main component, with a noble metal such as iridium oxide or a mixture of iridium oxide and tantalum oxide. It is a structure coated with a catalyst layer composed of an oxide mainly composed of a substance, and the electrode hardly wears when energized.
Further, it has a feature that the oxygen overvoltage is significantly lower than that of the lead electrode.

For example, in the production of an electrolytic copper foil, when an insoluble electrode of this kind whose base material is titanium or a titanium alloy containing it as a main component and whose catalyst layer is iridium oxide is used as an anode, conventional lead is used. Compared with the case where electrodes are used, the cell voltage can be lowered by about 1 V for operation, and the power consumption for energization can be significantly reduced. Moreover, since the electrodes are hardly consumed during the electrolytic operation, the distance between the electrodes does not change. Therefore, this electrode also has the advantage of stabilizing the operating conditions and the product quality.

However, although the above-mentioned oxygen generating electrode having the catalyst layer containing iridium oxide as the main component has the above-mentioned excellent characteristics, on the other hand, when the electrolytic operation is advanced, The electrolysis voltage may rise sharply after a certain period of time. Especially, when the electrolytic operation is carried out at a high current density, the above phenomenon occurs remarkably. Then, it is generally determined that the service life of the oxygen generating electrode is exhausted when such a phenomenon occurs.

The above-mentioned phenomenon is caused by the fact that an oxidizing substance generated on the surface of the electrode (catalyst layer surface) or a sulfuric acid component in the plating bath in the course of electrolytic operation penetrates from the catalyst layer to the surface of the substrate located therebelow. Then, by oxidizing the surface of the base material,
The adhesion between the base material and the catalyst layer is reduced, and an electrically insulating oxide film is formed on the surface of the base material, which causes a reduction in the conductivity of the entire oxygen generating electrode, and finally It is considered that this is because the electrolysis voltage increases.

Therefore, even if the insoluble oxygen generating electrode had excellent characteristics in the initial stage of use, the above-mentioned phenomenon occurs depending on the electrolysis conditions to be applied, and the life of the electrode is shortened. May be shorter. To solve such a problem, it has been proposed to form an underlayer made of a material having excellent corrosion resistance on the surface of the base material before forming the catalyst layer.

[0009] For example, in Japanese Patent Publication No. 49-48072, the base material is electrically or chemically oxidized in an aqueous solution containing a valve metal such as Ti, Ta, Nb or Zr. Thus, the oxide of the above metal is deposited on the surface of the base material, the thin oxide layer is formed as an underlayer, and then a catalyst layer made of a platinum group element or its oxide is formed on the underlayer. A method of forming has been proposed.

However, according to this method, the adhesion at the interface between the underlayer and the catalyst layer is not so good, so that when used as an oxygen generating electrode, the action of the oxidizing substance generated on the electrode surface causes the underlayer and the catalyst layer. The interfacial peeling between and gradually progresses, and eventually it becomes impossible to function as an electrode having excellent durability. Further, in JP-A-57-116786, a base material is immersed in an aqueous solution in which Ti, Ta, Zr, Hf and Nb are dissolved, and the base material is processed in the same manner as in JP-B-49-48072. A method is disclosed in which an oxide layer of the above metal is formed on the surface by electrodeposition and then a part of the oxide layer is heat-treated in a non-oxidizing atmosphere. Also in the case of this method, a relatively thick underlayer can be formed between the substrate surface and the catalyst layer. However, the adhesion between the base layer formed by this method and the substrate is poor.

In Japanese Patent Publication No. Sho 60-21232, Ta is formed on the surface of a base material made of Ti or a Ti alloy.
Or / and by thermally decomposing the compound of Nb,
A method has been proposed in which a mixed oxide of a Ti oxide existing as a thin film on the surface of a base material and an oxide of Ta and / or Nb is formed as an underlayer. However, the above-mentioned underlayer made of a mixed oxide has poor adhesion to the substrate and poor corrosion resistance. Therefore, after all, it cannot function as a long-life electrode.

Further, in Japanese Patent Publication No. 60-22074, a thin layer of a mixed oxide of an oxide of Ti and / or Sn and an oxide of Ta and / or Nb is formed on the surface of a base material by a thermal decomposition method. An electrode formed as a base layer has been proposed. However, in the case of this electrode, even though the underlayer has a certain degree of conductivity, it is not possible to use it in Japanese Patent Publication No. 60-2.
As in the case of the electrode disclosed in Japanese Patent No. 1232, since it is a mixed oxide, it has poor corrosion resistance, and the passivation of the surface of the base material progresses during the use process, and it is difficult to expect a long life.

Further, in JP-B-3-27635 and JP-A-2-61083, at least one selected from the group consisting of Ta, Ti, Nb, Sn and Zr between the base material and the catalyst layer. An electrode has been proposed in which a mixed oxide of the oxide of 1 and the Ir oxide is interposed as a base layer. Although the underlayers disclosed here have good conductivity,
Since this underlayer is also made of a mixed oxide, it has poor corrosion resistance as in the case of the electrode described above. Therefore, this electrode cannot be expected to have a long life.

[0014]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the conventional oxygen generating electrode and has an underlayer having excellent corrosion resistance between the base material and the catalyst layer, Excellent adhesion at each interface between the formation layer and the catalyst layer, and an oxygen generation electrode that can be used for a long period of time while maintaining a low oxygen generation overvoltage even under high current density use conditions. For the purpose of provision.

[0015]

In order to achieve the above-mentioned object, in the present invention, a base material of which at least the surface is made of titanium alone or a titanium alloy; only a titanium oxide formed on the surface of the base material is used. A single layer of titanium oxide consisting of: at least one layer formed on the surface of the single layer of titanium oxide, containing an oxide of an element other than a platinum group element as a main component,
An intermediate layer composed of a mixed oxide of the same and an oxide of a platinum group element; and a catalyst layer formed on the surface of the intermediate layer and composed of a mixed oxide containing a platinum group element oxide as a main component. An oxygen generating electrode (hereinafter, referred to as a first electrode) is provided.

Further, a base material having at least a surface made of titanium alone or a titanium alloy; a titanium oxide single layer formed only on the surface of the base material and containing only titanium oxide; formed on the surface of the titanium oxide single layer. An oxide single layer composed of an oxide of an element other than platinum group and titanium; at least one layer formed on the surface of the oxide single layer, containing an oxide of an element other than the platinum group element as a main component, and the platinum group element An intermediate layer formed of a mixed oxide with the oxide of the above; and a catalyst layer formed on the surface of the intermediate layer and formed of a mixed oxide containing an oxide of a platinum group element as a main component. A characteristic oxygen generating electrode (hereinafter referred to as a second electrode) is provided.

In the present invention, when the electrode for oxygen generation having the above-mentioned structure is produced, the titanium oxide single layer is coated with the titanium compound on the surface of the base material, and then the temperature is 400 to 400 ° C. There is provided a method for producing an oxygen generating electrode, which is formed by thermally decomposing the titanium compound in an oxygen-containing atmosphere at 650 ° C. Further, at the time of forming the titanium oxide single layer, the base material is immersed in an electrolytic solution, and an electric quantity of ³ mAh / cm ² or less is applied under a potential of 0.5 to 15 V with respect to a standard hydrogen electrode potential standard. An electrolytic oxidation treatment is performed to form a titanium oxide layer having a thickness of 1 to 20 nm on the surface of the base material, and then a titanium compound is applied onto the titanium oxide layer, and then an oxygen-containing atmosphere at a temperature of 400 to 650 ° C. There is provided a method for producing an oxygen generating electrode, characterized in that the titanium compound is thermally decomposed to form a titanium oxide layer.

Layer structures of the first electrode and the second electrode of the present invention are shown in FIGS. As the base material 1 in the electrode of the present invention, both the first electrode and the second electrode are used, at least the surface of which is composed of a simple substance of Ti or a Ti alloy. That is, as the base material 1, a material which is entirely formed of Ti alone or a Ti alloy, or a material such as stainless steel is used as a core material, and the surface thereof is formed by lamination, PVD method, CVD method, or the like. A simple substance of Ti or a film coated with a Ti alloy by the film method is used.

As the simple substance of Ti, any of the first type Ti and the second type Ti defined in JIS H 4600 can be used, and as the Ti alloy, for example,
6% Al-4% V-Ti alloy and 15% Mo-5% Zr-
A 3% Al-Ti alloy or the like can be used. Substrate 1
The shape is not particularly limited, and may be a shape according to the use as an electrode, such as a plate shape, a rod shape, or a lath shape. It is usually plate-shaped.

The surface of such a substrate 1, that is, Ti
In both the first electrode and the second electrode, the titanium oxide single layer 2 made of only Ti oxide is directly formed on the surface made of a simple substance or a Ti alloy. Prior to the formation, the titanium oxide film formed on the surface of the base material 1 is usually removed during the production of the base material 1 or while the base material 1 is left in the atmosphere.
This is because if the titanium oxide single layer 2 is formed on the titanium oxide film without removing the titanium oxide film, the adhesion of the titanium oxide single layer 2 is hindered.

The clean surface of the substrate from which the titanium oxide film is removed has a surface roughness Rz defined by JIS B0601 of 5 to 100 μm, preferably 10 to 40 μm.
If roughened, the surface of the substrate and the titanium oxide single layer 2
Adhesion strength with the titanium oxide single layer 2 and the intermediate layer 3 described later, or the oxide single layer 5, or the intermediate layer 3 or the oxide single layer 5 and the catalyst layer 4 formed thereon. It is preferable because the adhesion strength with can be increased.

The method of removing the titanium oxide film on the surface of the substrate to be used and roughening the surface of the cleaned substrate is preferably electrolytic etching using an aqueous oxalic acid solution. , Concentration 5-40% by weight, liquid temperature 5
A method of immersing the base material in an aqueous oxalic acid solution at 0 to 100 ° C, preferably 90 to 100 ° C for about 1 to 8 hours, or a concentration of 5 to 5
A method of immersing the base material in a 50% aqueous solution of sulfuric acid, using the base material as an anode, and etching at a current density of 5 to 30 A / dm ² for about 1 to 10 minutes can be adopted.

As the method for forming the titanium oxide single layer 2 of the present invention, a titanium compound solution is applied to the surface of the base material which has been subjected to the roughening treatment by removing the titanium oxide film as described above. After coating, it is pyrolyzed to form a Ti oxide layer, and when the surface of the base material is electrolytically oxidized to form an extremely thin layer of Ti oxide having excellent adhesion to the base material. In some cases, a solution of a titanium compound is further applied thereon, and the solution is pyrolyzed to laminate a Ti oxide layer to form a Ti oxide layer having a two-layer structure.

In the former method, first, for example, a solution prepared by dissolving a Ti compound in a predetermined solvent is applied to the surface of a base material, and then the applied layer is thermally decomposed in an oxygen-containing atmosphere to obtain a Ti oxide. Form a layer consisting of only. The Ti oxide produced by the above-mentioned thermal decomposition method varies depending on the heating temperature and the oxygen concentration in the atmosphere, but its composition is usually represented by TiO _2-x (0 <x <0.5). The composition is non-stoichiometric and the layer is electrically conductive.
Even if an oxidizing substance such as oxygen generated on the electrode surface enters from the electrode surface toward the base material, TiO _{2−x is} slightly oxidized (x slightly increases), so that the base material surface becomes electrically conductive. It is possible to prevent the oxide film from being covered with a static insulating film.

For example, titanium tetra-n-butoxide may be added to n
-Dissolved in butyl alcohol, the solution on the substrate surface,
For example, after applying directly with a brush or spray, 12
The coating layer is dried at a temperature of about 0 ° C., and then the whole is heated in the atmosphere at 400 to 650 ° C., preferably 440 to 500 ° C. for 5 to 60 minutes, preferably 10 to 20 minutes to form the coating layer. By thermal decomposition, a titanium oxide single layer 2 composed of the above-described non-stoichiometric Ti oxide is formed.
Can be formed. The titanium oxide single layer 2 formed under these conditions has a conductivity of 0.1 to 10 mS / cm, and has sufficient conductivity as an electrode.

T when forming the titanium oxide single layer 2
Even if the operation of applying the i-compound-pyrolysis is only once, the service life of the electrode can be sufficiently extended, but the above-mentioned operation may be repeated a plurality of times. The thickness of the titanium oxide single layer 2 is preferably 0.1 to 5 μm, particularly 0.5.
It is preferably ˜2 μm. This is because if the thickness is less than 0.1 μm, the corrosion resistance of the titanium oxide single layer 2 when the electrode is actually used is insufficient, and if it is more than 5 μm, sufficient conductivity cannot be obtained.

In the latter method, the surface of the base material whose surface has been cleaned is subjected to electrolytic oxidation treatment in advance, so that the surface of the base material is oxidized with Ti having a structure produced under limited conditions. An electrode having more excellent properties can be obtained by converting the material into a substance and further laminating the Ti oxide layer by the above-mentioned thermal decomposition method thereon. For electrolytic oxidation, aqueous solution of inorganic acid such as sulfuric acid, nitric acid, phosphoric acid;
An aqueous solution of an inorganic salt such as sodium sulfate or potassium sulfate; a substrate is immersed in an aqueous solution of an inorganic alkali such as sodium hydroxide or potassium hydroxide, the substrate 1 is used as an anode, for example, platinum is used as a cathode, and between both electrodes, 3m under the potential of 0.5 to 15V, preferably 1.5 to 3V with respect to the standard hydrogen electrode potential reference
A method of energizing with an electric quantity of Ah / cm ² or less is preferable.

When the Ti compound applied on the Ti oxide layer 2a by electrolytic oxidation is heated in an oxygen-containing atmosphere to form the Ti oxide layer 2b, for example, 350 to 60.
It is preferable to perform heat treatment in the atmosphere of 0 ° C. for about 5 to 120 minutes. The Ti oxide layer 2a formed by the electrolytic oxidation treatment described above may be formed of a Ti oxide including a so-called epitaxial layer, which itself is converted into an oxide while maintaining the Ti structure on the surface of the base material as it is. For that purpose, a thin layer having a thickness of 1 to 20 nm is preferable. If the thickness is more than 20 nm, the adhesion to the surface of the base material will be poor, and a layer with poor density will be formed on the surface, and the adhesion to the intermediate layer 3 formed thereon will also be poor. Further, if the thickness is less than 1 nm, it will not exhibit sufficient corrosion resistance by itself. A more preferable thickness of the Ti oxide layer 2a formed by electrolytic oxidation is 2 to 5
nm.

When such an electrolytic oxidation treatment is carried out, the surface of the base material 1 itself is converted into an oxide in the formed oxide layer, so that the adhesion strength between the layer and the base material 1 is extremely high. Get higher By the way, the Ti oxide layer 2a formed by the above-mentioned electrolytic oxidation treatment has excellent adhesion to the base material 1, but its thickness is extremely thin, so that it is difficult to exhibit sufficient corrosion resistance by itself. Therefore, a thick Ti oxide layer 2 is formed on the Ti oxide layer 2a by the thermal decomposition method described above.
It is necessary to form b. In this case, since both layers are made of Ti oxide, the mutual affinity is good and the adhesion strength between both layers is high. The layer formed by the electrolytic oxidation treatment has high adhesion strength to the base material 1 for the above-mentioned reason, so that the Ti oxide layer (titanium oxide single layer 2 in the present invention) composed of both layers is Adhesion with the substrate 1 is significantly improved.

Since the titanium oxide single layer 2 is composed of only Ti oxide, not a mixed oxide,
Its corrosion resistance is excellent. In the first electrode, as shown in FIG. 1, on the surface of the titanium oxide single layer 2 as described above,
A layer made of a mixed oxide described later is formed as the intermediate layer 3. In this case, the mixed oxide is Ta, Nb, Sn,
Oxides of elements other than platinum such as W, Ru, Rh,
It is composed of an oxide of a platinum group element such as Pd, Os, Ir and Pt.

That is, the base layer in the first electrode is composed of the titanium oxide single layer 2 and the intermediate layer 3 composed of the mixed oxide layer laminated thereon. Of these mixed oxides, the former oxide acts to make the formed intermediate layer 3 denser, and is an intermediate layer between the titanium oxide single layer 2 made of Ti oxide and the catalyst layer 4 described later. Positioned at, it works to increase adhesion. In addition, the latter oxide is the intermediate layer 3
It also has a function of imparting conductivity to the intermediate layer 3 while maintaining the denseness of the above.

In this mixed oxide, the former oxide must be the main component. In particular,
The ratio of the former oxide to the latter oxide is preferably 50 to 95 mol% in terms of metal equivalent chemical equivalent. It is particularly preferably 70 to 85 mol%. The mixture ratio of the former oxide is 5 in terms of the metal equivalent chemical equivalent.
When it is less than 0 mol%, the denseness of the intermediate layer 3 becomes poor and the adhesiveness to the titanium oxide single layer 2 also deteriorates. It easily penetrates to the surface of the material, resulting in shortened life.
Further, when the former is more than 95 mol% in terms of metal equivalent chemical equivalent, the conductivity of the intermediate layer 3 is deteriorated, and the function as the oxygen generating electrode cannot be sufficiently exhibited.

The former oxide has excellent oxidation resistance,
Ta oxide is preferable because it has a good affinity with the Ti oxide and can make the intermediate layer 3 dense, and the latter oxide imparts conductivity to the intermediate layer 3. Ir oxide is preferable not only because it can be used, but also because it enhances the adhesion to the catalyst layer 4 described later.

The intermediate layer 3 preferably has a thickness of 0.1 to 10 μm. Particularly preferably, it is 1 to 5 μm. If this thickness is less than 0.1 μm, it will be difficult to effectively prevent the electrolyte solution and oxidizing substances from entering the surface of the base material during actual use as an electrode.
Even if the thickness is larger than m, the effect reaches saturation, and the material used for forming the layer is wasted.

The intermediate layer 3 can be formed by the above-mentioned thermal decomposition method. That is, a compound of an element other than the platinum group element and a compound of the platinum group element are dissolved in an appropriate solvent at a predetermined ratio, and the obtained solution is applied onto the titanium oxide single layer 2 described above, The coating layer can be formed by thermal decomposition in an oxygen-containing atmosphere. At this time, the use ratio of each compound is determined in relation to the target mixing ratio of the oxide in the intermediate layer 3 to be formed.

For example, when the intermediate layer 3 of a mixed oxide composed of Ta oxide and Ir oxide is formed, tantalum chloride or tantalum penta-n-butoxide and iridium chloride hexahydrate are added to n-butyl. After dissolving in alcohol and applying the solution to the surface of the titanium oxide single layer 2,
It is dried at a temperature of about 120 ° C, and then the whole is 400-
5 in the atmosphere at 650 ° C, preferably 440 to 550 ° C
The coating layer may be thermally decomposed by heating for 60 minutes, preferably 10 to 20 minutes.

The intermediate layer 3 may have only one layer, but may have a plurality of layers by performing the above-mentioned coating-pyrolysis operation a plurality of times. On the other hand, in the case of the second electrode of the present invention, as shown in FIG. 2, on the titanium oxide single layer 2, an oxide single layer 5 made of an oxide of an element other than platinum group and titanium, and platinum. An intermediate layer 3 similar to the first electrode, which is mainly composed of an oxide of an element other than a group element and is made of a mixed oxide of an oxide of a platinum group element, is laminated in this order. That is, the base layer in the second electrode is composed of the titanium oxide single layer 2, the oxide single layer 5, and the intermediate layer 3 made of a mixed oxide.

The oxide constituting the oxide-only layer 5 is
Any oxide may be used as long as it is a single oxide that is excellent in durability and is composed of oxides of elements other than platinum group and titanium.
Ta oxide, Nb oxide, Sn oxide, etc. can be mentioned. Of these, Ta oxide is preferable. Since the oxide-only layer 5 is dense and has high strength and good corrosion resistance, it prevents the electrolytic solution and the oxidizing substance from invading the surface of the base material when the electrode is actually used. Work. In particular, when the oxide single layer 5 is composed of Ta oxide, in addition to the above-mentioned function, it also has a function of enhancing both the adhesiveness with the titanium oxide single layer 2 and the adhesiveness with the intermediate layer 3 described later. So it is useful.

The oxide single layer 5 has a thickness of 0.01-1.
It is preferably 0 μm. This is because if the thickness is less than 0.01 μm, the above-mentioned effects are not sufficiently exhibited, and if it is more than 10 μm, the adhesion to the titanium oxide single layer 2 is deteriorated. More preferably 0.02 to 1.0
μm. This oxide-only layer 5 can be formed by the above-mentioned thermal decomposition method.

For example, when the Ta oxide single layer 5 is formed, for example, a solution obtained by dissolving tantalum chloride in n-butyl alcohol or a solution obtained by dissolving tantalum penta-n-butoxide in n-butyl alcohol is titanium. After coating on the oxide layer 2b, the coating layer is dried at a temperature of about 120 ° C. Then the whole is 400-650
The coating layer is pyrolyzed by heating in the atmosphere at 50 ° C., preferably 440 to 550 ° C. for 5 to 60 minutes, preferably 10 to 20 minutes, and the tantalum oxide film is a single oxide film on the titanium oxide layer 2b. Formed as layer 5.

When the oxide single layer 5 is formed by the thermal decomposition method, the service life of the electrode can be sufficiently extended even if the above-mentioned coating-pyrolysis operation is performed once, but there are more than one. The above operation may be repeated once. Then, the intermediate layer 3 is formed on the oxide-only layer 5 in the same manner as the first electrode.

In this second electrode, the functions of the respective layers constituting the underlayer are effectively combined to be exerted, and the electrode is excellent in corrosion resistance. In each of the first electrode and the second electrode, as shown in FIGS. 1 and 2, the catalyst layer 4 is formed on the above-mentioned base layer. This catalyst layer 4 is R
It is composed of a mixed oxide containing an oxide of a platinum group element such as u, Rh, Pd, Os, Ir and Pt as a main component.

Examples of oxides other than platinum group element oxides include Ta oxide, Nb oxide, Ti oxide, and S.
Examples thereof include n oxide. Then, a mixed oxide in which the main component is Ir oxide and the other oxide is Ta oxide is suitable as the catalyst layer 4. In that case, the Ir oxide is preferably 50 to 95 mol% in terms of chemical equivalent to Ir metal. It is particularly preferably 55 to 65 mol%.

When the ratio of Ir oxide is less than 50 mol% in terms of chemical equivalent to Ir metal, the catalytic activity of the catalyst layer 4 is lowered, and conversely, when it exceeds 95 mol%, the catalyst layer becomes less. This is because the density of No. 4 is deteriorated and the corrosion resistance of the entire electrode is deteriorated. The thickness of the catalyst layer 4 is not particularly limited, but if it is too thin, the function as the catalyst layer 4 is not sufficiently exerted, and if it is too thick, the effect only reaches saturation, which causes an increase in manufacturing cost. Therefore, it is usually set to about 3 to 30 μm.

When the catalyst layer 4 composed of Ir oxide as a main component and Ta oxide is mixed, for example, iridium chloride hexahydrate and tantalum penta-n-butoxide are mixed at a desired ratio of n- After dissolving in butyl alcohol and applying the obtained solution on the above-mentioned intermediate layer 3, the temperature is 120 ° C.
The coating layer is dried at a moderate temperature. Then the whole 4
The coating layer may be thermally decomposed by heating in the atmosphere at 00 to 550 ° C, preferably 440 to 520 ° C for 5 to 60 minutes, preferably 10 to 20 minutes.

By repeating this coating-pyrolysis operation several times to several tens of times, a mixed oxide layer is formed on the underlayer to form the catalyst layer 4 having a desired thickness.

[0047]

Next, of these first and second electrodes, for example, the first electrode having a layer structure as shown in FIG. 1, that is, the base material 1 is Ti, and the titanium oxide single layer 2 is electrolytic oxidation. A Ti oxide layer 2b formed by a thermal decomposition method is further laminated on the Ti oxide layer 2a formed in 1., the intermediate layer 3
Is formed by a thermal decomposition method and contains Ta oxide as a main component and a mixed oxide layer composed of the Ta oxide and Ir oxide, and the catalyst layer 4 contains Ir oxide as a main component and the Ir oxide. T
The function of each layer will be described in the case of an electrode which is a layer of a mixed oxide composed of a-oxide.

First, since the titanium oxide single layer 2 is composed only of the Ti oxide layer 2a formed by electrolytic oxidation and the Ti oxide layer 2b having a non-stoichiometric composition, it has sufficient conductivity as an electrode. It is equipped with good corrosion resistance itself. Therefore, even if the electrolytic solution or the oxidizing substance may enter from the surface of the electrode when the electrode is actually used, the titanium oxide single layer 2 is rarely eroded by these oxidizing substances.

Even if an oxidizing substance such as oxygen generated on the electrode surface invades from the electrode surface toward the substrate 1 and the titanium oxide single layer 2 is eroded, in that case,
TiO _{2−x is} slightly oxidized (x is slightly increased), the invasion of the oxidizing substance to the base material 1 side is suppressed, and the surface of the base material 1 is electrically insulating. Covering with a film can be prevented. That is, the titanium oxide single layer 2 functions as a barrier layer for the base material 1.

Further, since the Ti oxide layer 2a is a layer in which the surface itself of the base material 1 is converted into an oxide, the adhesion strength with the base material 1 is high, and the Ti oxide layer 2a is formed on the Ti oxide layer 2a. Since the Ti oxide layer 2b formed is the same Ti oxide,
The i oxide layer 2a has a good affinity and is strongly adhered.
Therefore, the titanium oxide single layer 2 including the Ti oxide layer 2a and the Ti oxide layer 2b has good adhesion to the substrate 1 as a whole.

Therefore, the titanium oxide single layer 2 and the substrate 1 are
Interfacial peeling from the surface of the substrate is unlikely to occur, and the situation in which the surface of the substrate is passivated by the oxidizing substance or the like is effectively prevented. The intermediate layer 3 is composed of a metal oxide having good adhesion to the titanium oxide single layer 2 and a catalyst metal oxide for improving adhesion to the catalyst layer 4, and comprises Ta oxide and Ir oxidation. The mixed oxide layer of the product itself has excellent corrosion resistance and is dense, and is between the titanium oxide single layer 2 composed of the Ti oxide and the catalyst layer 4 composed mainly of Ir oxide as described above. By interposing them, these two layers are firmly adhered to each other.

Therefore, the intermediate layer 3 suppresses the invasion of the electrolytic solution and the oxidizing substance from the surface of the electrode when the electrode is actually used, and thus these oxidizing substances passivate the surface of the base material so that electricity cannot be supplied. Control the situation of becoming. That is,
Prolong the service life of the electrode. As described above, in the case of the first electrode, since the titanium oxide single layer 2 and the intermediate layer 3 having the above-described functions are interposed between the base material 1 and the catalyst layer 4 in this order, the electrode During actual use, progress of interfacial peeling between layers and passivation of the surface of the base material due to an oxidizing substance or the like penetrating from the electrode surface are effectively prevented. Therefore, this electrode can function as a long-life oxygen generating electrode.

[0053]

Examples of the invention

Example 1 A type II Ti plate having a length of 200 mm, a width of 20 mm and a thickness of 2 mm was degreased and washed with acetone and then dried. Next, this Ti
The plate was placed in an oxalic acid aqueous solution with a concentration of 10% by weight (liquid temperature 90 ° C).
After being immersed in the plate for 5 hours for roughening treatment, it was washed with water and dried. The surface roughness Rz specified by JISB0601 is 15
A Ti plate of -20 μm was obtained.

Titanium tetra-n-butoxide (34.0 g) was dissolved in n-butyl alcohol to prepare a total solution of 100 ml. This solution is brushed on the surface of a Ti plate, the coating layer is dried at a temperature of 120 ° C. for 3 minutes, and further heated in the air at a temperature of 450 ° C. for 10 minutes to form a Ti layer having a thickness of about 1 μm. An oxide layer was formed.

Then, 17.4 g of tantalum penta-n-butoxide and 4.1 g of iridium chloride hexahydrate were added to n-.
A solution having a total volume of 100 ml was prepared by dissolving in butyl alcohol, and the solution was brushed on the surface of the Ti oxide, and then the coating layer was dried at a temperature of 120 ° C. for 3 minutes and further heated at a temperature of 450. Consisting of a mixed oxide of Ta oxide and Ir oxide, which is heated for 10 minutes in the atmosphere of ℃,
An intermediate layer having a thickness of about 1 μm was formed.

The mixing ratio of Ta oxide in this intermediate layer was about 81 mol% in terms of Ta metal equivalent. Next, 12.2 g of chloroiridate hexahydrate and 8.7 g of tantalum penta-n-butoxide were dissolved in n-butyl alcohol to prepare a 100 ml total solution for the catalyst layer.

This solution was brushed on the surface of the above-mentioned intermediate layer, dried at a temperature of 120 ° C. for 3 minutes, and then heated in the air at 450 ° C. for 10 minutes to thermally decompose each component of the solution. Then, a mixed oxide film was formed, and the operation of brush coating, drying and thermal decomposition of the solution was repeated four times to form a catalyst layer having a thickness of about 4 μm. The final heating time was 1 hour.

The mixing ratio of Ir oxide in this catalyst layer was about 60 mol% in terms of chemical equivalent to Ir metal. Thus, the electrode of Example 1 was manufactured. Example 2 The solution used for forming the intermediate layer was tantalum penta-n-
13.1 g butoxide and iridium chloride hexahydrate 8.1
An electrode was produced in the same manner as in Example 1 except that g was dissolved in n-butyl alcohol to prepare 100 ml in total.

The mixing ratio of Ta oxide in this intermediate layer was about 61 mol% in terms of chemical equivalent to Ta metal. Example 3 The solution used for forming the intermediate layer was 14.7 g of niobium penta-n-butoxide and ruthenium chloride crystals (Ru content, 3
9 wt%) 2.1 g was dissolved in n-butyl alcohol to prepare 100 ml in total, and the solution used for forming the catalyst layer was iridium chloride.
Hexahydrate 12.2 g and niobium penta-n-butoxide 7.3
An electrode was produced in the same manner as in Example 1 except that g was dissolved in n-butyl alcohol to prepare 100 ml in total. The mixing ratio of the Nb oxide in this intermediate layer is about 80 mol% in terms of Nb metal equivalent, and the mixing ratio of the Ir oxide in the catalyst layer is about 60 in terms of Ir metal equivalent.
It was mol%.

Comparative Example 1 The catalyst layer solution used in Example 1 was directly applied to the surface of the Ti plate which had been roughened in Example 1 and then the temperature was adjusted to 1
It is dried at 20 ° C. for 3 minutes, and further heated in the air at 450 ° C. for 10 minutes to thermally decompose each component to form a mixed oxide film, which is again brushed, dried and thermally decomposed. This operation was repeated 4 times to form a catalyst layer having a thickness of about 4 μm.

The electrode was manufactured in this manner. Comparative Example 2 An electrode was produced in the same manner as in Example 1 except that the intermediate layer was not formed. Comparative Example 3 An electrode was produced in the same manner as in Example 1 except that the titanium oxide single layer 2 was not formed. Comparative Example 4 As a solution for the intermediate layer, 9.8 g of tantalum penta-n-butoxide and 11.3 g of iridium chloride hexahydrate were added.
An electrode was prepared in the same manner as in Example 1, except that a solution prepared by dissolving in butyl alcohol to a total volume of 100 ml was used. The mixing ratio of Ta oxide in this intermediate layer is about 45 in terms of Ta metal equivalent chemical equivalent.
It was mol%.

Comparative Example 5 A Ti plate, which had been roughened in Example 1, was used as an anode and a platinum plate was used as a cathode, and a sulfuric acid aqueous solution having a concentration of 1 mol% (liquid temperature 3) was used.
(0 ° C.) as an electrolytic solution, and a direct current voltage of about 2 V with respect to the standard hydrogen electrode potential is applied between both electrodes for 1 minute to perform electrolytic oxidation treatment (electric quantity, 0.03 mAh / cm ² ). Ti with a Ti oxide layer with a thickness of about 3 nm formed on the surface of the Ti plate
A solution prepared by dissolving 17.0 g of titanium-n-butoxide and 27.3 g of tantalum penta-n-butoxide in n-butyl alcohol to 100 ml was applied to the surface of the plate, and then applied at a temperature of 120 ° C for 3 minutes. And dry, then 4
The mixture was heated in the atmosphere at 50 ° C. for 10 minutes for thermal decomposition, and this operation was repeated twice to form a mixed oxide layer composed of Ti oxide and Ta oxide and having a thickness of about 1 μm. In this layer, the mixing ratio of Ti oxide is about 50 mol% in terms of Ti metal equivalent chemical equivalent.

Then, a catalyst layer was formed on this layer in the same manner as in Example 1 to manufacture an electrode. Comparative Example 6 A Ti plate, which had been subjected to the surface roughening treatment in Example 1, was used as an anode and a platinum plate was used as a cathode, and an aqueous sulfuric acid solution having a concentration of 1 mol% (liquid temperature 3
(0 ° C.) as an electrolytic solution, and a direct current voltage of about 30 V with respect to the standard hydrogen electrode potential is applied between both electrodes for 1 minute for electrolytic oxidation treatment (electricity, 6 mAh / cm ² ). Ti oxide having a thickness of about 50 nm was formed on the surface of the. A Ti oxide layer, an intermediate layer and a catalyst layer were respectively formed on the surface of the electrolytically oxidized substrate by thermal decomposition in the same manner as in Example 1.

The electrodes of Examples 1 to 3 and Comparative Examples 1 to 6 were respectively treated with an aqueous solution of sulfuric acid having a concentration of 1 mol / l (liquid temperature 10
It was immersed in 0 ° C.) as an anode and a platinum plate as a cathode, and a DC voltage was applied between both electrodes to energize at a current density of 100 A / dm ² . When the anode is operating normally, the terminal voltage is 3 ~
It is 5V. However, when the anode deteriorates, the anode potential sharply rises and the terminal voltage also sharply rises to 10 V or more.

The time from the start of energization to the terminal voltage exceeding 10 V was measured. The results are collectively shown in Table 1.

[0066]

[Table 1] Examples 4 to 17 and Comparative Examples 7 to 10 The first electrode was manufactured as follows.

Second length 200 mm, width 20 mm, thickness 2 mm
The seed Ti plate was degreased and washed with acetone and then dried. Next, this Ti plate was immersed in an aqueous solution of oxalic acid having a concentration of 10% by weight (liquid temperature 90 ° C.) for the time shown in Table 2 to roughen the surface, then washed with water and dried. A Ti plate having a surface roughness Rz specified in JIS B0601 shown in Table 2 was obtained.

The Ti plates used in Examples 7 and 8 were subjected to physical surface roughening treatment by sandblasting using an alumina abrasive having an average particle diameter of 300 μm. Next, these Ti plates were used as anodes, platinum plates were used as cathodes, and a sulfuric acid aqueous solution (solution temperature 30 ° C.) having a concentration of 1 mol% was used as an electrolytic solution to carry out electrolytic oxidation under the conditions shown in Table 2 to obtain the indicated thickness. Of Ti oxide layer 2a was formed.

Also, titanium tetra-n-butoxide 34.
Dissolve 0 g in n-butyl alcohol and total 100 ml
Was prepared. This solution is brush-coated on the Ti oxide layer 2a formed on the surface of the Ti plate, and then the coating layer is dried at a temperature of 120 ° C. for 3 minutes, and further in the air at a temperature of 450 ° C. After heating for 10 minutes, the thickness is about 1μ
m Ti oxide layer 2b was formed.

Then, 17.4 g of tantalum penta-n-butoxide and 4.1 g of iridium chloride hexahydrate were added to n-.
A solution of 100 ml in total was prepared by dissolving in butyl alcohol, and the solution was brush-coated on the surface of the Ti oxide layer 2b, and then the coating layer was dried at a temperature of 120 ° C. for 3 minutes. By heating in the air at a temperature of 450 ° C. for 10 minutes, an intermediate layer 3 composed of a mixed oxide of Ta oxide and Ir oxide and having a thickness shown in Table 2 was formed.

In Comparative Example 7, 2.2 g of tantalum penta-n-butoxide and 18.4 g of iridium chloride hexahydrate were dissolved in n-butyl alcohol to give a total solution of 100 ml. In Comparative Example 8, tantalum penta-n-butoxide (6.5 g) and iridium chloride hexahydrate (14.4 g) were dissolved in n-butyl alcohol to give a total solution of 100 ml. For Example 9, tantalum penta-n-butoxide 2
The intermediate layer 3 was formed by using 1.3 g and 0.4 g of iridium chloride hexahydrate dissolved in n-butyl alcohol to obtain a total solution of 100 ml.

The mixing ratio of the Ta oxide in the intermediate layer 3 was as shown in Table 2 in terms of Ta metal equivalent chemical equivalent. Next, 12.2 g of iridium chloride hexahydrate
And 8.7 g of tantalum penta-n-butoxide were dissolved in n-butyl alcohol to prepare a total 100 ml solution for the catalyst layer.

This solution was brushed on the surface of the intermediate layer 3 described above, dried at a temperature of 120 ° C. for 3 minutes, and then heated in the air at 450 ° C. for 10 minutes to heat each component of the solution. The film was decomposed into a mixed oxide film, and the procedure of brush coating, drying, and thermal decomposition of the solution was repeated four times to form a catalyst layer 4 having a thickness of about 4 μm. The final heating time was 1 hour.

In Comparative Example 9, 2.1 g of iridium chloride hexahydrate and 18.2 g of tantalum penta-n-butoxide were dissolved in n-butyl alcohol to give a total solution of 100 ml. For Comparative Example 10, 6.5 g of iridium chloride hexahydrate and tantalum penta-n
-Butoxide 14.1 g was dissolved in n-butyl alcohol to make a total solution of 100 ml. For Example 10, iridium chloride hexahydrate 21.0 g and tantalum penta-n-butoxide 0. A catalyst layer 4 was formed by using 4 g and n-butyl alcohol dissolved in n-butyl alcohol to obtain a total solution of 100 ml.

The mixing ratio of Ir oxide in these catalyst layers 4 was as shown in Table 2 in terms of Ir metal equivalent chemical equivalent. Each of these electrodes was immersed in a sulfuric acid aqueous solution (solution temperature 100 ° C.) having a concentration of 1 mol / l to serve as an anode, and a platinum plate was used as a cathode to apply a DC voltage between the electrodes to 100 A /
Current was applied at a current density of dm ² .

When the anode is operating normally, the terminal voltage is 3-5V. However, when the anode deteriorates, the anode potential rises sharply and the terminal voltage rises sharply with it.
It becomes V or more. The time from the start of energization to the terminal voltage exceeding 10 V was measured. The results are collectively shown in Table 2.

[0077]

[Table 2]

As is clear from Table 2, Examples 6-
The electrode of No. 8 has the same layer structure as that of the electrode of Example 4 except that the surface roughness of the substrate surface is different, but the time until the terminal voltage of these electrodes exceeds 10V, In other words, comparing the lifetimes, the lifetime of the electrodes of Examples 6 to 8 is about 1/3 of the lifetime of the electrode of Example 4, which is very short.
Further, the electrode of Example 9 has the same layer structure as the electrode of Example 4 except that the ratio of Ta oxide in the intermediate layer is different.
The life of the electrode of Example 9 is about 1 / the life of the electrode of Example 4.
2, which is very short. Further, the electrode of Example 10 has the same layer structure as the electrode of Example 4 except that the ratio of Ir oxide in the catalyst layer is different. The life of the electrode of Example 10 is about 1/4 of the life of the electrode of Example 4, which is very short.

Thus, the layer structure of the electrodes is the same,
It is also found that even if the conditions of electrolytic oxidation are the same, if the roughened state of the surface of the base material or the composition of the intermediate layer or the catalyst layer changes, the life of the electrode also greatly changes. In addition, Example 1
The electrodes of Nos. 1 to 14 were different from each other except that the conditions of electrolytic oxidation were different and the thickness of the Ti oxide layer 2a was different.
Although it has the same layer structure as the electrode of Example 1, the lifetime of this electrode is also about 2/5 to 2/3 of the lifetime of the electrode of Example 4, and the lifetimes of the electrodes of Examples 11 to 14 are very short. It's getting shorter. Further, the electrodes of Examples 15 to 17 have the same layer structure as that of the electrode of Example 4 except that the thickness of the intermediate layer 3 is different. The life of the electrodes of Examples 15 to 17 is about 1/3 to 1/2 of the life of the electrode of Example 4, which is very short.

As described above, it can be seen that even if the layer structure of the electrodes is the same, if the thickness of the Ti oxide layer 2a or the thickness of the intermediate layer 3 changes, the life of the electrodes also changes significantly. Therefore, in the oxygen generating electrode of the present invention, in order to further prolong its life, the intermediate layer 3 and the Ti oxide layer 2a are formed.
It is preferable to set the forming conditions of the above conditions to those shown in claims 5 and 9.

Examples 18 to 31, Comparative Examples 11 to 14 The second electrode was manufactured as follows. Length 200m
A second type Ti plate of m, width 20 mm and thickness 2 mm was degreased and washed with acetone and then dried. Next, this Ti plate was immersed in an aqueous solution of oxalic acid having a concentration of 10% by weight (solution temperature 90 ° C.) for the time shown in Table 3 to roughen the surface, then washed with water and dried.

Surface roughness Rz specified by JISB0601
A Ti plate having the values shown in Table 3 was obtained. In addition, Example 2
1. The Ti plate used in Example 22 had an average particle diameter of 300 μm.
The surface-roughening treatment was physically performed by sandblasting using an alumina abrasive material of m.

Then, using these Ti plates as anodes and platinum plates as cathodes, an aqueous sulfuric acid solution having a concentration of 1 mol% (liquid temperature 30
(.Degree. C.) as an electrolytic solution and electrolytic oxidation was performed under the conditions shown in Table 3 to form the Ti oxide layer 2a having the indicated thickness. Also,
Titanium tetra-n-butoxide (34.0 g) was dissolved in n-butyl alcohol to prepare a total solution of 100 ml.

This solution was brush-coated on the Ti oxide layer 2a formed on the surface of the Ti plate, the coating layer was dried at a temperature of 120 ° C. for 3 minutes, and then the temperature was adjusted to 45.
After heating for 10 minutes in the atmosphere of 0 ° C, the thickness of T is about 1 μm.
The i oxide layer 2b was formed. Then, tantalum penta
A total of 100 ml of solution was prepared by dissolving 1 g of n-butoxide in n-butyl alcohol.

After this solution was brush coated on the titanium oxide layer 2b, the coating layer was dried at a temperature of 120 ° C. for 3 minutes and then heated in the atmosphere at a temperature of 450 ° C. for 10 minutes to tantalum. An oxide single layer 5 made of an oxide was formed. Next, 17.4 g of tantalum penta-n-butoxide and 4.1 g of iridium chloride hexahydrate were dissolved in n-butyl alcohol to prepare a solution of 100 ml in total. After brushing the surface of the single layer 5, the coating layer is dried at a temperature of 120 ° C. for 3 minutes,
Further, it was heated in the air at a temperature of 450 ° C. for 10 minutes to form an intermediate layer 3 composed of a mixed oxide of Ta oxide and Ir oxide and having a thickness shown in Table 3.

The mixing ratio of the Ta oxide in the intermediate layer 3 was as shown in Table 3 in terms of Ta metal equivalent chemical equivalent. And finally, iridium chloride hexahydrate 1
2.2 g of tantalum penta-n-butoxide and 8.7 g of n-
A solution for a catalyst layer of 100 ml in total was prepared by dissolving in butyl alcohol, the solution was brushed on the surface of the intermediate layer 3 described above, dried at 120 ° C. for 3 minutes, and further 450 ° C. In the atmosphere for 10 minutes, each component of the solution is thermally decomposed to form a mixed oxide film, and the operation of brush coating-drying-pyrolysis of the solution is repeated 4 times to obtain a thickness of about 4 μm. Catalyst layer 4 was formed. The final heating time was 1 hour.

The mixing ratio of Ir oxide in these catalyst layers 4 was as shown in Table 3 in terms of Ir metal equivalent chemical equivalent. The solutions used in Comparative Examples 7 and 8 and Example 9 were used when forming the intermediate layer 3 in Comparative Examples 11 and 12 and Example 23, respectively. Further, when forming the catalyst layer 4 in Comparative Examples 13 and 14 and Example 24, the solutions used in Comparative Examples 9 and 10 and Example 10 were used, respectively.

Each of these electrodes had a concentration of 1 mol / mol.
l soak in a sulfuric acid aqueous solution (liquid temperature 100 ° C) to make an anode,
Applying a DC voltage between both electrodes with the platinum plate as the cathode, 100
Current was applied at a current density of A / dm ² . When the anode is operating normally, the terminal voltage is 3-5V. However, when the anode deteriorates, the anode potential sharply rises and the terminal voltage also sharply rises to 10 V or more.

The time from the start of energization to the terminal voltage exceeding 10 V was measured. The results are collectively shown in Table 3.

[0090]

[Table 3]

As is clear from Table 3, Example 20
The electrodes of Nos. 22 to 22 have the same layer structure as the electrodes of Example 18 except that the surface roughness of the substrate surface is different, but the time until the terminal voltage of these electrodes exceeds 10V. That is, comparing the lifetimes, the lifetimes of the electrodes of Examples 20 to 22 are about 1/3 of the lifetimes of the electrodes of Example 18, which is very short. In addition, the electrode of Example 23 was the same as T in the intermediate layer.
Example 18 except that the proportions of a oxides are different.
The electrode has the same layer structure as that of the electrode of Example 23. However, the lifetime of the electrode of Example 23 is compared with that of Example 18 by comparing the lifetimes of this electrode.
It is very short, about 1/2 of the life of the electrode. Furthermore, the electrode of Example 24 has the same layer structure as the electrode of Example 18 except that the proportion of Ir oxide in the catalyst layer is different. The life of the electrode of Example 24 is about 1/4 of the life of the electrode of Example 18, which is very short.

Thus, the layer structure of the electrodes is the same,
It is also found that even if the conditions of electrolytic oxidation are the same, if the roughened state of the surface of the base material or the composition of the intermediate layer or the catalyst layer changes, the life of the electrode also greatly changes. Example 2
The electrodes of Nos. 5 to 28 have different electrolytic oxidation conditions, and the thickness of the Ti oxide layer 2a is different.
Although it has the same layer structure as the electrode of Example 8, the lifetimes of the electrodes of Examples 25 to 28 are very short, about 1/2 of the lifetime of the electrode of Example 18, when the lifetimes of this electrode are compared. There is. Further, the electrodes of Examples 29 to 31 have the same layer structure as that of the electrode of Example 18 except that the thickness of the intermediate layer 3 is different. The lifetimes of the electrodes of Examples 29 to 31 are about 1/3 to 1/2 that of the electrodes of Example 18, which is very short.

As described above, even if the electrode layer structure is the same, it can be seen that if the thickness of the Ti oxide layer 2a or the thickness of the intermediate layer 3 changes, the life of the electrode also changes significantly. Therefore, in the oxygen generating electrode of the present invention, in order to further prolong its life, the intermediate layer 3 and the Ti oxide layer 2a are formed.
It is preferable to set the forming conditions of the above conditions to those shown in claims 5 and 9.

[0094]

The oxygen-generating electrode according to claim 1 has a surface of T
A titanium oxide single layer made of only a Ti oxide having excellent corrosion resistance and excellent adhesion to the base material between the base material made of i or Ti alloy and the catalyst layer, and the titanium oxide single layer By interposing an intermediate layer, which is formed on the layers and has excellent corrosion resistance and denseness, during the actual use of the electrodes, the interfacial peeling between layers progresses and oxidative substances, etc., invade from the electrode surface. Since it can be effectively prevented from coming in, the service life of the electrode is extended.

The surface of the oxygen generating electrode according to claim 2 is Ti.
Alternatively, a titanium oxide single layer made of only a Ti oxide having excellent corrosion resistance and excellent adhesion to the substrate between the base material made of a Ti alloy and the catalyst layer, and this titanium oxide single layer Formed on the oxide single layer consisting of oxides of elements other than platinum group and titanium, which is dense and has high strength and good corrosion resistance, and is formed on this oxide single layer, By interposing an intermediate layer with excellent corrosion resistance and denseness, it is possible to effectively prevent interfacial delamination between layers and the ingress of oxidizing substances from the electrode surface during actual use of the electrode. Since it can be prevented, the service life of the electrode is further extended.

In the oxygen generating electrode according to the third aspect, the titanium oxide alone layer is formed on the surface of the base material by the thermal decomposition method and is composed of only the Ti oxide. Sufficient conductivity is imparted. In the oxygen generating electrode according to claim 4, the titanium oxide single layer has a two-layer structure including a Ti oxide layer formed by electrolytically oxidizing the surface of the base material and a Ti oxide layer formed by a thermal decomposition method. Therefore, the titanium oxide single layer has excellent conductivity and the adhesion to the substrate is significantly improved. Therefore, sufficient conductivity is imparted to the electrode and the durability is further improved.

In the oxygen-generating electrode of the fifth aspect, since the layer made of the mixed oxide of Ta oxide and Ir oxide is used as the intermediate layer, the intermediate layer has excellent conductivity. The adhesion to the titanium oxide single layer and the catalyst layer is improved. Therefore, sufficient conductivity is imparted to the electrode and the durability is further improved. In the oxygen generating electrode according to claim 6, since the oxide single layer is a layer made of only Ta oxide, which is dense and has high strength and good corrosion resistance, the electrolyte solution or the oxidizing substance is used as the base. It can be prevented from penetrating into the surface of the material, and the Ta oxide single layer also serves to enhance both the adhesion to the titanium oxide single layer and the adhesion to the intermediate layer. Therefore, the durability of the electrode is further improved.

In the oxygen-generating electrode according to the seventh aspect, since the catalyst layer is a layer formed of a mixed oxide of Ir oxide and Ta oxide, the catalyst layer has a high catalytic activity and is dense. It becomes a simple structure. Therefore, the oxygen generation capability of the electrode is good, and at the same time, it is possible to effectively prevent the inflow of an oxidizing substance or the like from the electrode surface, and further improve the corrosion resistance.

A method for manufacturing an oxygen generating electrode according to claim 8 is:
This is a method of forming a titanium oxide single layer composed of a Ti oxide on the surface of a substrate by thermal decomposition of a Ti compound, and the oxygen generation electrode formed by this method has sufficient conductivity as an electrode. . The method for producing an electrode for oxygen generation according to claim 9 is a method of electrolytically oxidizing a surface of a base material to form a Ti oxide layer, and further forming a Ti oxide layer thereon by a thermal decomposition method. The oxygen generating electrode thus formed has excellent adhesion between the base material and the titanium oxide single layer, and has sufficient conductivity as an electrode.

As is clear from the above description, the electrode of the present invention has excellent durability and long service life, and is useful as an insoluble oxygen generating electrode in the electrolytic industry.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of a first electrode of the present invention.

FIG. 2 is a sectional view showing a layer structure of a second electrode of the present invention.

[Explanation of symbols]

 1 Base Material 2 Titanium Oxide Single Layer 2a Ti Oxide Layer (by Electrolytic Oxidation) 2b Ti Oxide Layer (by Pyrolysis Method) 3 Intermediate Layer 4 Catalyst Layer 5 Oxide Single Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // C25D 1/04 311

Claims (9)

[Claims] 1. A base material having at least the surface made of titanium alone or a titanium alloy; a titanium oxide single layer formed only on the surface of the base material and containing only titanium oxide; and at least 1 on the surface of the titanium oxide single layer. An intermediate layer formed of a mixed oxide of an oxide of an element other than the platinum group element as a main component and a platinum group element oxide; and a platinum group element of the intermediate layer formed on the surface of the intermediate layer. An electrode for oxygen generation, comprising: a catalyst layer made of a mixed oxide containing an oxide as a main component. 2. A base material having at least a surface made of titanium alone or a titanium alloy; a titanium oxide single layer formed only on the surface of the base material and containing only titanium oxide; formed on the surface of the titanium oxide single layer. An oxide single layer composed of an oxide of an element other than platinum group and titanium; at least one layer formed on the surface of the oxide single layer, containing an oxide of an element other than the platinum group element as a main component, and the platinum group element An intermediate layer formed of a mixed oxide with the oxide of the above; and a catalyst layer formed on the surface of the intermediate layer and formed of a mixed oxide containing an oxide of a platinum group element as a main component. Characteristic oxygen generation electrode. 3. The oxygen generating electrode according to claim 1, wherein the titanium oxide single layer is a titanium oxide layer formed by a thermal decomposition method of a titanium compound. 4. The titanium oxide single layer is formed by electrolytically oxidizing the surface of the base material and a titanium oxide layer formed on the titanium oxide layer by a thermal decomposition method of a titanium compound. The oxygen generating electrode according to claim 1 or 2, which comprises a titanium oxide layer. 5. The intermediate layer is made of a mixed oxide of tantalum oxide and iridium oxide and has a thickness of 0.1 to 1.
The electrode for oxygen generation according to claim 1 or 2, which has a thickness of 0 μm. 6. The oxygen generating electrode according to claim 2, wherein the oxide single layer made of an oxide of elements other than platinum group and titanium is made of only tantalum oxide. 7. The oxygen generating electrode according to claim 1, wherein the catalyst layer is made of a mixed oxide of iridium oxide and tantalum oxide. 8. When manufacturing the oxygen generating electrode according to claim 1, 2, 3, 4, 5, 6, or 7, a titanium oxide single layer is applied, and a titanium compound is applied to the surface of a substrate. After that, the titanium compound is formed by thermally decomposing the titanium compound in an oxygen-containing atmosphere at a temperature of 400 to 650 ° C. 9. When manufacturing the oxygen generating electrode according to claim 1, 2, 3, 4, 5, 6, or 7, a titanium oxide single layer is prepared by immersing a base material in an electrolytic solution to obtain standard hydrogen. A titanium oxide layer having a thickness of 1 to 20 nm is formed on the surface of the base material by applying an electric amount of 3 mAh / cm ² or less at a potential of 0.5 to 15 V with respect to the electrode potential standard to perform electrolytic oxidation treatment. Then, a titanium compound is applied onto the titanium oxide layer, and then the titanium compound is thermally decomposed in an oxygen-containing atmosphere at a temperature of 400 to 650 ° C. to form a titanium oxide layer. For manufacturing electrodes for use.