JP2983114B2 - Electrode for electrolysis and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for electrolysis used in an electrolysis process of a metal electrolyte containing a hydrophilic organic compound such as glue or thiourea, and a method for producing the same. More specifically, the present invention provides an electrolysis solution having excellent durability and a low oxygen overvoltage, which is preferably used for a reaction in which an aqueous metal solution containing a predetermined hydrophilic organic compound is electrolyzed to generate oxygen at an anode. The present invention relates to an electrode for use and a method for easily and efficiently manufacturing the electrode.

[0002]

2. Description of the Related Art Conventionally, metal electrodes having a conductive substrate made of metallic titanium and provided with a coating layer of a platinum group metal or its oxide have been used in various fields of the electrolytic industry.
For example, an electrode in which a ruthenium and titanium oxide or a ruthenium and tin oxide is coated on a titanium substrate is known as an anode for chlorine generation by salt electrolysis (Japanese Patent Publication No. 46-21884, JP-B-48-3954, JP-B-50-11330).

In the electrolysis industry, in addition to electrolysis involving the generation of chlorine as in the case of the above-mentioned salt electrolysis, recovery of acids, alkalis or salts, collection and purification of metals such as copper and zinc, plating, metal foil production Electrolytic processes involving the generation of oxygen, such as metal surface treatment, cathodic protection, and waste liquid treatment, are also used in many fields. And, in such electrolysis involving the generation of oxygen, a lead-based electrode is most commonly used. In addition, as insoluble electrodes, electrodes coated with iridium oxide and platinum on a titanium substrate, iridium oxide-tin oxide-based electrodes, iridium oxide-iridium oxide-based electrodes such as tantalum oxide-based electrodes, and platinum-plated titanium electrodes are known. I have.

[0004] However, these known electrodes cause various troubles depending on their use, and are not always suitable. For example, when a soluble zinc anode is used as an anode for galvanizing, the dissolution of the anode is remarkable, so the distance between the electrodes must be adjusted frequently,
In addition, when a lead-based insoluble anode is used, poor plating occurs due to the effect of lead mixed in the electrolytic solution. In addition, when performing so-called high-speed zinc plating at a high current density of 100 A / dm ² or more, the platinum-plated titanium electrode is extremely consumed and cannot be used.

[0005] Therefore, it is one of the important issues in the electrode manufacturing technology to develop an electrode that can be applied without any obstacle for each application of the electrolytic process involving the generation of oxygen.
It is one. As an example of such a special electrolysis process, an electrolytic solution containing glue, thiourea, or the like as an additive may be used in electrolysis processes of various metals such as electrorefining of copper and production of copper foil.

In such a case, Japanese Patent Application Laid-Open No. 63-23549
No. 3 discloses that Ir50 to 90 mol%, Ta50 to 10
An iridium oxide-tantalum oxide based electrode provided with a mol% underlayer is disclosed. This electrode exhibits practically sufficient durability as a plating anode containing no hydrophilic organic compound additive in the plating bath. However, it has been found that when glue or the like is added to the plating bath, there is a case where durability is reduced and practicality is lost.

In general, when electrolysis involving oxygen generation is performed using a titanium substrate electrode having a coating layer as an anode, a titanium oxide layer is formed between the substrate and the coating layer, and the anode potential gradually increases, and finally the The phenomenon of delamination and passivation of the anode is often observed. This phenomenon is particularly remarkable in an electrolytic process in which glue or the like is added to the electrolytic solution.

In order to suppress the formation of titanium oxide formed on such a titanium substrate and to prevent the passivation of the anode, it is necessary to select an appropriate coating layer or provide an appropriate underlayer. It has been proposed.

For example, Japanese Patent Publication No. 51-19429 discloses an electrode having an intermediate barrier layer that is relatively thin, conductive, and relatively impermeable to oxygen. JP-B-49-48072 discloses that an electrode substrate is immersed in an aqueous solution containing a film-forming metal ion as an intermediate layer, and an oxide of the film-forming metal is deposited from this solution by electric or chemical oxidation. A method of manufacturing an electrode that forms an intermediate layer by performing the method is disclosed.
However, when glue or the like is added, the electrode catalyst layer cannot be used due to severe consumption of the electrode catalyst layer and insufficient durability.

Further, in Japanese Patent Application Laid-Open No. 47-33773, since tantalum oxide is stable in an electrolytic solution, a coating layer made of tantalum oxide and an oxide of another valence metal is used as a surface coating layer of the electrode. It has been proposed to do so. Further, JP-A-49-79971 discloses that a tantalum oxide layer is formed on the surface of an electrode catalyst layer, between electrode catalyst layers, or
It is disclosed to provide as an intermediate layer between the substrate and the electrode catalyst layer. However, since tantalum oxide is a substance having poor conductivity, in the case where tantalum oxide is provided as an intermediate layer between the base and the electrode catalyst layer, a tantalum oxide layer must be formed on the base before forming the tantalum oxide layer. And

Since tantalum oxide is stable in an electrolytic solution, it is suitable as an intermediate layer material for suppressing oxidation of a titanium substrate formed between a titanium substrate and an electrode catalyst layer and preventing passivation of an anode. I have. However, since tantalum oxide alone has poor conductivity, reduction treatment of tantalum oxide, addition of a metal or metal oxide having another valence to tantalum oxide, or formation of a tantalum oxide layer Attempts have been made to improve the conductivity of tantalum oxide having poor conductivity, for example, by making it thinner. However, in these proposals, the electrolysis process using glue or the like as an additive has not yet functioned as a sufficiently satisfactory intermediate layer.

For example, Japanese Patent Publication No. 64-11718 discloses a tantalum oxide intermediate layer partially reduced by forming a tantalum oxide layer on a titanium substrate and subjecting it to a heat treatment in a non-oxidizing atmosphere. Is disclosed. However, in this case, an electric furnace for suppressing the atmosphere for forming the tantalum suboxide layer is required, and the production cost is increased.

JP-A-1-301876, JP-A-2-61083 and JP-A-3-193889 disclose an intermediate layer comprising tantalum oxide and iridium oxide, or tantalum oxide, iridium oxide and platinum. An electrode is disclosed. However, since iridium and platinum are used for the intermediate layer, the cost is high, and since the intermediate layer itself is active and its durability is poor, satisfactory performance in terms of electrode life and deterioration of oxygen overvoltage with time is required. I can't get it.

JP-A-60-21232 discloses that an intermediate layer of tantalum oxide is provided in a thickness of 0.001 to 1 g / m ^{2 in} terms of metal to impart conductivity to titanium oxide formed on the surface of a substrate. An electrode is disclosed. However, since the intermediate layer is thin, the effect of protecting the titanium base and preventing passivation of the electrode is reduced, and it is difficult to obtain an electrode having sufficient durability.

Furthermore, it has been found that in the examples of combination of the intermediate layer and the upper layer disclosed in each of these publications, the electrolysis process using glue or the like as an additive does not show sufficient durability. Under such circumstances, even when the electrolytic solution contains a hydrophilic organic compound such as a glue, an electrode having excellent durability without causing abnormal consumption has been desired.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrode for electrolyzing an electrolytic solution containing a glue component or a thiourea-based compound. An object of the present invention is to provide an electrode which can be used, has a long life and is excellent in durability, and a method for producing the electrode.

[0017]

Means for Solving the Problems When the glue component or a thiourea compound is used as an additive, the present inventors
When providing an iridium oxide-tantalum oxide layer on a conductive substrate such as titanium, only when the composition ratio of iridium and tantalum is regulated within a predetermined range, abnormal consumption is suppressed and high durability is obtained. Was found. In addition, at this time, it has been found that when a base layer made of tantalum oxide having a specific thickness is provided, abnormal wear is further suppressed and durability is further improved. Therefore, the above object is achieved by the following configurations (1) to (7). (1) On a conductive substrate, iridium 75 to 9 in terms of metal
An electrolysis electrode provided with a layer of iridium oxide and tantalum oxide containing 5 atomic% and 5 to 25 atomic% of tantalum, and for performing electrolysis of a metal electrolytic solution containing a glue component or a thiourea-based compound. (2) The electrode for electrolysis according to (1), wherein the metal electrolyte contains copper. (3) On the conductive substrate, 0.2 mg / c of tantalum in metal conversion
An upper layer of iridium oxide and tantalum oxide containing 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal is provided via an underlayer of tantalum oxide of m ² or more, and a glue component or Electrolysis electrode for electrolysis of metal electrolyte containing thiourea compound. (4) The electrode for electrolysis according to (3), wherein the amount of tantalum oxide carried on the underlayer is 1.0 to 5.0 mg / cm ² in terms of metal. (5) The electrode for electrolysis according to (3) or (4), wherein the metal electrolyte contains copper. (6) A solution containing an iridium compound and a tantalum compound is applied on a conductive substrate, and then heat-treated in an oxidizing atmosphere to contain 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal. A method for producing an electrode for electrolysis, wherein a layer of iridium oxide and tantalum oxide is formed to obtain the electrode for electrolysis according to the above (1) or (2). (7) A solution containing a tantalum compound is first applied on a conductive substrate, and then heat-treated in an oxidizing atmosphere to form a tantalum oxide underlayer of 0.2 mg / cm ² or more in terms of metal, Then, a solution containing an iridium compound and a tantalum compound is applied thereon, and then heat-treated in an oxidizing atmosphere to obtain iridium oxide containing 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal. And a layer made of tantalum oxide to form
(5) A method for producing an electrode for electrolysis, wherein the electrode for electrolysis is obtained.

[0018]

[Specific Configuration] Hereinafter, a specific configuration of the present invention will be described in detail.

Examples of the conductive substrate used in the electrode of the present invention include valve metals such as titanium, tantalum, zirconium, and niobium, and alloys of two or more metals selected from these valve metals. .

In the electrode of the present invention, a layer substantially composed of iridium oxide and tantalum oxide is provided on these conductive substrates, and the ratio of each component of this layer is 75 to 95% in terms of metal in terms of metal. Atomic%, tantalum 5-2
It must be in the range of 5 atomic%.

Good results are obtained only in this range. When the iridium content is less than 75 atomic%, iridium oxide tends to be selectively consumed as compared with tantalum oxide during electrolysis, and overvoltage occurs during electrolysis. And the life of the electrode is shortened. On the other hand, if the iridium content exceeds 95 atomic%, the adhesion strength of the electrode film becomes poor.

The thickness of such a coating layer is preferably such that the amount of iridium oxide carried is about 0.5 to 7 mg / cm ^{2 in} terms of metal.

In the present invention, an underlayer substantially made of tantalum oxide is provided with the above-mentioned coating layer as an upper layer. This coating layer needs to be applied in an amount of 0.2 mg / cm ² or more in terms of tantalum. This amount is 0.2mg / cm ²
This is because the effect of protecting the titanium base as the underlayer is sufficiently exerted as described above. In such a case, as in the present invention, under the conditions that a hydrophilic organic compound such as glue is contained as an additive in an electrolytic solution such as for producing an electrolytic copper foil, the electrode consumption is accelerated, and the deterioration of the titanium substrate is greatly accelerated. 1.0 mg / cm ^{2 to} 5.0 of tantalum base layer in tantalum conversion
Even better results are obtained when applied in an amount of mg / cm ² .
If the amount is 1.0 mg / cm ² or more, the risk that the electrolytic solution containing glue or the like reaches the titanium substrate surface is eliminated, and the effect of protecting the titanium substrate is further increased. In addition, when the amount of the underlayer carried is large, the resistance of the underlayer itself is increased together with the amount. Therefore, when used at a high current density, if the amount is too large, the conductivity of the underlayer deteriorates, and the underlayer has poor conductivity. Due to the resistance, power loss occurs, and the effect as the underlayer may not be sufficiently exhibited.

Next, a preferred embodiment for manufacturing the above-mentioned electrode for electrolysis will be described. First, a solution containing an iridium compound and a tantalum compound is applied on a conductive substrate, and then the solution is applied in an oxidizing atmosphere. By heat treatment, a layer containing iridium oxide and tantalum oxide containing 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal is formed. Coating solution used at this time, compounds to be iridium oxide by thermal decomposition, for example, iridium acid _{(H 2 IrCl 6 · 6H 2} O) chloride, and iridium compound such as iridium chloride, compounds comprising tantalum oxide by thermal decomposition, for example It can be adjusted by dissolving a tantalum compound such as a tantalum halide such as tantalum chloride or a tantalum alkoxide such as ethoxy tantalum in an appropriate solvent at a predetermined ratio. This heat treatment in an oxidizing atmosphere is performed by applying the coating solution on a conductive substrate, drying the coating solution, and then drying the coating solution in the presence of oxygen.
Oxygen partial pressure of 5 atm or more, preferably 400 to 600 ° C
By firing at a temperature in the range of
This operation is repeated a plurality of times until the required carrying amount is reached.

Another embodiment will be described. First, a solution containing a tantalum compound is applied to a conductive substrate, and then heat-treated in an oxidizing atmosphere to form a base layer made of tantalum oxide. The coating solution used at this time is
It can be prepared by dissolving a compound that becomes tantalum oxide by thermal decomposition, for example, a tantalum compound such as tantalum halide such as tantalum chloride or tantalum alkoxide such as ethoxy tantalum in an appropriate solvent at a predetermined ratio. . This heat treatment in an oxidizing atmosphere is performed by applying the coating solution on a conductive substrate, drying the coating solution, and then in the presence of oxygen, generally at an oxygen partial pressure of 0.05 atm or more, preferably at 400 to 550 ° C. This is done by firing at a range of temperatures. This operation is repeated a plurality of times until the required carrying amount is reached.

A solution containing an iridium compound and a tantalum compound is applied on the tantalum oxide underlayer formed as described above, and then heat-treated in an oxidizing atmosphere to obtain 75 to 95 atoms of iridium in terms of metal. % Of iridium oxide and tantalum oxide containing 5-25 atomic% of tantalum. Coating solution used at this time, compounds to be iridium oxide by thermal decomposition, for example, iridium acid _{(H 2 IrCl 6 · 6H 2} O) chloride, and iridium compound such as iridium chloride, compounds comprising tantalum oxide by thermal decomposition, for example It can be prepared by dissolving a tantalum compound such as a tantalum halide such as tantalum chloride or a tantalum alkoxide such as ethoxy tantalum in an appropriate solvent at a predetermined ratio.

The heat treatment in an oxidizing atmosphere is performed by applying the coating solution on the coating layer, drying the coating solution, and firing the coating solution in the presence of oxygen, preferably at a temperature in the range of 400 to 600 ° C. Done. This operation is repeated a plurality of times until the required load is reached. In this way, an upper layer having a desired carrying amount is applied on the coating layer, and the electrode of the present invention is obtained.

If the heat treatment for forming these coating layers, ie, the underlayer and the upper layer, is not performed in an oxidizing atmosphere, the oxidation becomes insufficient and the metal is present in a free state, so that the resulting electrode is obtained. The durability is reduced.

The electrode for electrolysis manufactured in this way is
It is used as an anode in electrolysis of a metal electrolyte containing a glue component or a thiourea-based compound, that is, an oxygen generating electrode. Copper, nickel, zinc,
Iron, tin, bismuth, antimony, arsenic, various noble metals, and the like are possible, but favorable results are obtained particularly when copper is used. Any of these various electrolytic solutions used in electrolytic processes such as metal purification, metal sampling, metal foil production, plating, and drainage treatment can be applied.

The glue component as an additive includes glue of various animal origins as well as gelatin. The thiourea-based compound includes thiourea and its derivatives.
The electrode for electrolysis of the present invention may contain one or more of
It is applicable to an electrolyte containing 10 g / l. The metal content may be in the range of 1 to 200 g / l. Further, as the hydrophilic organic compound, avidone, safranin, lignin, and the like may be further contained. The electrolytic bath temperature is 10 to 80 ° C., and the current density is 0.1 to
It can be used at 300 A / dm ² .

[0031]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention.

Examples 1 to 8 and Comparative Examples 1 to 7 As shown in Table 1, iridium chloride (H ₂ IrCl _{6) was used} at a predetermined ratio such that iridium oxide and tantalum oxide corresponded to a predetermined composition ratio. 6H ₂ O) and tantalum ethoxide [Ta (OC ₂ H ₅ ) ₅ ] are dissolved in butanol to change the composition ratio of iridium / tantalum, and the metal-equivalent concentration of 80 g / l is applied to the undercoat or overcoat. The liquid was adjusted.

Separately, the base coating solution was applied by a brush on a titanium substrate etched with hot oxalic acid, dried, and then baked in an electric furnace at 500 ° C. while blowing air. The operations of coating, drying and baking were repeated an appropriate number of times until a predetermined carrying amount was reached, thereby producing various coating base layers of iridium oxide and tantalum oxide shown in Table 1. However, a part was formed as a single-layer film coating. The amount of tantalum supported on the underlayer is 0.9 to 1.2 mg / cm ^2, and when the underlayer is used as a single-layer film, the amount of iridium supported is 1.3 to 1.6 mg / cm ² . did.

Further, the coating solution for upper layer was applied to the undercoat layer with a brush, dried, and then baked in an electric furnace at 500 ° C. while blowing air. The operations of coating, drying and baking were repeated an appropriate number of times until a predetermined carrying amount was reached, thereby producing an electrode sample in which the underlayer was covered with an upper layer of iridium oxide and tantalum oxide. The loading amount of iridium in the upper formation was 1.2 to 1.5 mg / cm ² .

Next, the oxygen overvoltage was measured for the electrode thus manufactured. The measurement method was as follows: a current density of 20 A /
The value at dm ² was determined.

The electrode was heated at 60.degree.
l Life test was conducted in sulfuric acid aqueous solution. Electrolysis was performed at a current density of 200 A / dm ² using platinum as a cathode and this electrode as an anode. The results are shown in Table 1. 1 mol / l
The electrode life in an aqueous sulfuric acid solution is ：: 2000 hours or more.
Δ: 1000 to 2000 hours, ×: less than 1000 hours.

Regarding the change with time of the electrode, the above life test was performed up to 1000 hours, the test was temporarily stopped, and the oxygen overvoltage after 1000 hours was obtained by the above-described method of measuring the oxygen overvoltage. The difference was evaluated for evaluation. The results are shown in Table 1. The change with time of the oxygen overvoltage was as follows: ：: less than 0.3 V, Δ: 0.3 to 0.7 V, ×:
It is indicated by an increase in overvoltage of 0.7 V or more.

Furthermore, electrolysis containing a hydrophilic organic compound additive
A life test was performed with the liquid. Electrolyte is 2mol / l sulfuric acid aqueous solution
100 ppm of glue, 50 ppm of thiourea, hydrochloric acid
100 ppm was used. The electrolyte temperature is
70 ° C, current density 200A / dm ^Two , Using a copper plate for the cathode
Was. The electrode life in this hydrophilic organic compound-containing electrolysis is ◎:
Over 1000 hours, ○: 600 to 1000 hours, Δ: 30
0 to 600 hours, x: 300 hours or less.

Further, in order to clarify the adhesion strength of the coating layer, the mechanical strength of the electrode during electrolysis was tested. The test method was to perform a life test in a 1 mol / l sulfuric acid aqueous solution for up to 1000 hours, then perform a vibration peel test by ultrasonic waves for 5 minutes, measure the film thickness before and after the vibration peel test by fluorescent X-ray analysis, and determine the weight loss. The required evaluation was performed. The peeling of the electrode thickness is ○: 5
%, Δ: 5 to 10%, ×: 10% or more.

[0040]

[Table 1]

Examples 9 to 13 and Comparative Examples 8 to 12 As shown in Table 2, tantalum ethoxide [Ta (O
C ₂ H ₅ ) ₅ ] was dissolved in butanol to prepare a coating solution for a base at 40 g / l in terms of tantalum metal. Further, at a predetermined rate, such as tantalum oxide and iridium oxide corresponding to a predetermined composition ratio, iridium chloride (H ₂ IrCl 6 _· 6
H ₂ O) and tantalum ethoxide [Ta (OC
₂ H ₅ ) ₅ ] was dissolved in butanol to prepare a coating solution for upper layer having a metal conversion concentration of 100 g / l in which the composition ratio of iridium / tantalum was changed.

Separately, the base coating solution was applied by a brush onto a titanium substrate etched with hot oxalic acid, dried, and then baked in an electric furnace at 500 ° C. while blowing air. These operations of coating, drying and baking were repeated an appropriate number of times until a predetermined carrying amount was reached, thereby producing a tantalum oxide underlayer shown in Table 2.

Further, the above-mentioned coating solution for upper layer was applied to this undercoat layer with a brush, dried, and then baked in an electric furnace at 500 ° C. while blowing air. The operations of coating, drying and baking were repeated an appropriate number of times until a predetermined carrying amount was reached, thereby producing an electrode sample in which the underlayer was covered with an upper layer of iridium oxide and tantalum oxide. The iridium carrying amount of the upper formation was 1.2 to 1.5 mg / cm ² .

Next, the oxygen overvoltage was measured for the electrode thus manufactured. The measuring method was as follows: the electric current density was 20 A / dm in a 1 mol / l sulfuric acid aqueous solution at 30 ° C. by the potential scanning method.
The value at ² was determined.

The electrode was heated at 60 ° C. and 4 mol / l.
A life test was performed in an aqueous sulfuric acid solution. Electrolysis was performed at a current density of 200 A / dm ² using platinum as a cathode and this electrode as an anode. The results are shown in Table 2.

The electrode life in a 4 mol / l sulfuric acid aqueous solution was as follows: ：: more than 2000 hours, Δ: 1000 to 2000 hours,
X: Displayed in 1000 hours or less.

Regarding the change with time of the electrode, the above life test was performed up to 1000 hours, the test was temporarily interrupted, and the oxygen overvoltage after 1000 hours was obtained by the above-described method of measuring the oxygen overvoltage. The evaluation was performed by determining the difference from

The results are shown in Table 2. The change with time of the oxygen overvoltage was as follows: ：: less than 0.3 V; Δ: 0.3 to 0.7 V;
×: Displayed as an increase in overvoltage of 0.7 V or more.

Further, a life test was performed using an electrolyte containing a hydrophilic organic compound additive. The electrolytic solution is 100 ppm of glue, 50 ppm of thiourea, 1 part of hydrochloric acid with respect to 2 mol / l sulfuric acid aqueous solution.
The one to which an amount of 00 ppm was added was used. Electrolyte temperature is 7
A copper plate was used at 0 ° C., a current density of 200 A / dm ² , and the cathode.
The electrode life in this hydrophilic organic compound-containing electrolysis was ◎: 1.
More than 000 hours, ○: 600-1000 hours, Δ: 300
-600 hours, x: 300 hours or less.

[0050]

[Table 2]

As is apparent from these results, the electrode of the present invention has a small change in oxygen overvoltage with time, a high mechanical adhesion strength, contains a glue component and a thiourea compound in the electrolytic solution, and has an oxygen generation reaction. In the electrolysis process, which significantly accelerates electrode wear, a critically long lifetime is obtained.

Actually, a sulfuric acid concentration of 100 g / l and a copper concentration of 50 g / l
l, an electrodeposited copper foil of 70 μm at a current density of 40 A / dm ² , using a sulfuric acid acidic copper electrolyte having a glue concentration of 10 mg / l, a stainless steel rotating cylinder as a cathode, and the electrodes of Examples 1 to 13 as anodes. Was produced continuously, and a stable copper foil could be obtained over a long period of time.

[0053]

When the electrode of the present invention is used as an anode in an electrolytic process of an electrolytic solution containing a glue component or a thiourea system, it can withstand long-term use at a low cell voltage, has excellent durability, and has a resistance of 100 A. Even if the electrolysis is performed at a high current density of / dm ² or more, it has excellent durability and can be used for a long time.

Continuation of the front page (72) Inventor Kazuhide Oe 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-63-235493 (JP, A) JP-A-2-294494 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) C25C 7/02 C25D 17/10, 17/12

Claims (7)

(57) [Claims] 1. An electrically conductive substrate is provided with a layer of iridium oxide and tantalum oxide containing 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal. Electrolysis electrode for electrolysis of a metal electrolyte containing a compound. 2. The metal electrolyte according to claim 1, wherein said metal electrolyte contains copper.
Electrodes for electrolysis. 3. An electroconductive substrate having a tantalum oxide base layer of 0.2 mg / cm ² or more of tantalum and a metal of 75 to 95 atom% of iridium and tantalum 5
An electrolytic electrode provided with an upper layer of iridium oxide and tantalum oxide containing up to 25 atomic%, and for electrolyzing a metal electrolyte containing a glue component or a thiourea-based compound. 4. The electrode for electrolysis according to claim 3, wherein the amount of tantalum oxide carried on the underlayer is 1.0 to 5.0 mg / cm ² in terms of metal. 5. The metal electrolyte according to claim 3, wherein the metal electrolyte contains copper.
Or the electrode for electrolysis of 4. 6. A conductive substrate is coated with a solution containing an iridium compound and a tantalum compound, and then heat-treated in an oxidizing atmosphere to obtain 75 to 95 atomic% of iridium in terms of metal.
A method for producing an electrode for electrolysis according to claim 1 or 2, wherein a layer of iridium oxide and tantalum oxide containing 5 to 25 atomic% of tantalum is formed. 7. A method for applying a solution containing a tantalum compound on a conductive substrate, followed by heat treatment in an oxidizing atmosphere;
An underlayer of tantalum oxide of 0.2 mg / cm ² or more in terms of metal is formed, and then a solution containing an iridium compound and a tantalum compound is applied thereon, followed by heat treatment in an oxidizing atmosphere, 6. A method for producing an electrode for electrolysis according to claim 3, wherein a layer comprising iridium oxide and tantalum oxide containing 75 to 95 atomic% of iridium and 5 to 25 atomic% of tantalum in terms of metal is formed. Method.