JPS5847471B2 - Manufacturing method of electrolytic assembly - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an electrolytic assembly.

The electrolytic assembly is a combination of a thin film and a metal that becomes an electrode, and its importance is increasing in the solid polymer electrolyte electrolysis method that is actually used in fields such as water electrolysis, hydrochloric acid or salt electrolysis. It's coming.

The currently frequently used electrolytic bonding body is one in which a certain type of metal layer is bonded to both sides of a cation exchange membrane.

Such a bonded body for electrolysis must have low electrical resistance, flexibility of the metal layer bonded to the cation exchange membrane, and good adhesion between the cation exchange membrane and the metal layer. It is required to have properties such as being 1, and having excellent durability without peeling of the metal layer during electrolysis.

Conventionally, as a manufacturing method of an electrolytic assembly, for example, USP No. 3,4 3 2, 3 5 5 and USP No. 3,2
9 7, 4 8 The method described in specification No. 4,
Various methods have been developed, such as the method described in Japanese Patent Publication No. 42-5014 and the method described in Japanese Patent Application Laid-Open No. 55-38934.

USP No. 3, 4 3 2, 3 5 5 specification and USP
The method described in Specification No. 3,297,484 is a so-called dry method in which metals such as platinum, iridium, rhodium, and ruthenium or their oxides are formed into a film in advance using polytetrafluoroethylene as a binder. This method is followed by thermocompression bonding of the membrane to an ion exchange membrane to obtain an electrolytic assembly.

Furthermore, the method described in Japanese Patent Publication No. 42-5014 and the method described in Japanese Patent Application Laid-open No. 55-38934 are so-called wet methods, and the former impregnates an ion exchange membrane with a solution containing a reducing agent. Next, the membrane is immersed in a metal salt solution to deposit the metal directly on the membrane surface.The latter is a method in which a metal salt solution and a reducing agent solution are placed through an ion exchange membrane, and the reducing agent is passed through the ion exchange membrane. This is a method in which a metal layer is formed on the membrane on the metal salt solution side by permeation.

However, none of the electrolytic assemblies obtained by these methods has all the properties required for the electrolytic assemblies described above.

In other words, USP No. 3,432,355 and U.S.P.
The electrolytic bonded body manufactured by the method described in SP No. 3,297,484 has a thick metal film of several tens to 100 microns, and the film is formed using polytetrafluoroethylene as a bond. Because of this, the electrical resistance is extremely high, and the adhesion and durability are insufficient.

Furthermore, in the method described in Japanese Patent Publication No. 42-5014, the amount of reducing agent impregnated onto the ion exchange membrane is limited;
Therefore, only a very thin metal layer is formed on the ion exchange membrane, and as a result, the electrolytic assembly produced by this method has poor adhesion and durability.

Furthermore, although the electrolytic assembly produced by the method described in JP-A-55-38934 is somewhat improved compared to the electrolytic assembly obtained by the above method, the method does not allow for uneven thickness. Therefore, a large amount of metal is required to form a metal layer on the ion exchange membrane that has the minimum necessary thickness no matter where it is picked up. Therefore, economic disadvantage is inevitable.

Furthermore, all of the conventional methods described above require complicated equipment and complicated operations, making it extremely difficult to produce large quantities of dog-shaped electrolytic conjugates.

In view of the current situation, the present inventor has conducted extensive research in order to develop a method for producing an electrolytic assembly free of the above-mentioned drawbacks.

During the research process, a method was developed in which salts of base metals such as nickel, cobalt, and copper were adsorbed onto the plastic surface at room temperature, and then treated with a reducing agent solution to reduce the metal salts to metal particles, followed by electroless plating. (Special Public Interest Publication No. 54-39812
We focused on the fact that there is a method (see Japanese Patent Publication No. 1), and attempted to manufacture an electrolytic assembly by applying such a method.

That is, a cation exchange membrane is selected from among plastics, salts of base metals such as nickel, cobalt, and copper are adsorbed onto the membrane at room temperature, and then treated with a reducing agent solution to reduce the metal salts to metal particles. Furthermore, an attempt was made to manufacture an electrolytic assembly by electroless plating.

However, if such a method is followed, only a trace amount of metal particles will be deposited on the cation exchange membrane due to the reducing agent treatment, and the metal layer obtained even if such a cation exchange membrane is electrolessly plated will be coated with cations. The electrolytic bond cannot be firmly adhered to the exchange membrane, and therefore the resulting electrolytic bond has poor adhesion, and is also insufficient in flexibility and durability, making it impossible for the electrolytic bond to withstand practical use. It turned out to be difficult to manufacture.

Next, the inventor selected a sodium borohydride solution from the reducing agent solutions, adsorbed salts of base metals such as nickel, cobalt, and copper on a cation exchange membrane at room temperature, and then added a sodium borohydride aqueous solution. An attempt was made to reduce the metal salts to metal particles by treating the metal with chlorine, and then perform electroless plating to produce an electrolytic bonded body.

However, even when this method is followed, as with the above method, only a trace amount of metal particles are deposited on the cation exchange membrane due to the sodium boron hydride treatment, and the cation exchange membrane is The metal layer obtained by electroless plating may be firmly adhered to the cation exchange membrane, but the resulting electrolytic bonded body has poor adhesion and is also insufficient in flexibility and durability. However, it has been found that it is extremely difficult to produce an electrolytic assembly that can withstand practical use.

As a result of further research, we found that ions of a metal belonging to the platinum group, which is completely different from the above-mentioned base metals, were ion-exchanged and adsorbed onto a cation exchange membrane at room temperature to high temperature, and then treated with an aqueous solution of boron hydride salt. Electrical resistance can be reduced only if the ion exchange membrane is brought into contact with a specific alkaline aqueous solution containing a salt of the metal and a dialkylamine borane. It has been found that a desired electrolytic bonded body which is small in size and has excellent flexibility, adhesiveness and durability can be obtained.

The present invention was completed based on this knowledge.

That is, in the present invention, metal ions belonging to the platinum group are ion-exchanged and adsorbed onto a cation exchange membrane at room temperature to high temperature, and then treated with a boron hydride salt aqueous solution to deposit a metal layer on the inner surface of the membrane. The present invention relates to a method for producing a bonded body for electrolysis, which comprises bringing the membrane into contact with an alkaline aqueous solution containing a salt of the metal described above and a dialkylamine borane to lengthen the metal layer on the membrane surface.

According to the method of the present invention, the electrical resistance is extremely low, the metal layer bonded to the cation exchange membrane has flexibility, the adhesion between the cation exchange membrane and the metal layer is good, and It is possible to produce an electrolytic bonded body that has all the properties required for an electrolytic bonded body, such as no peeling of the metal layer during electrolysis and excellent durability.

Furthermore, the method of the present invention does not require complicated equipment or complicated operations, and therefore can easily mass-produce dog-shaped electrolytic conjugates.

Furthermore, in the method of the present invention, a metal layer having an arbitrary thickness can be bonded by selecting conditions for contacting a cation exchange membrane treated with ion exchange adsorption and a boron hydride salt aqueous solution with a specific alkaline aqueous solution. A conjugate for electrolysis can be obtained.

In addition, the electrolytic assembly obtained by the present invention has uniform micropores in the metal layer, which allows for smooth water replenishment and gas release during electrolysis, making it extremely desirable as an electrolytic assembly. It is something.

In the method of the present invention, metal ions belonging to the platinum group are first ion-exchanged and adsorbed onto a cation exchange membrane at room temperature to high temperature (adsorption step).

The cation exchange membrane is not particularly limited and a wide variety of known membranes can be used, but it is particularly preferable to use a perfluorinated hydrocarbon resin membrane having sulfonic acid groups or carboxylic acid groups.

The thickness of the cation exchange membrane used is usually 0.05 to 0.
About 41ILr/L, preferably 0.1 to 0.31n7
It is about 1L.

Specific examples of metals belonging to the platinum group include platinum, rhodium, ruthenium, palladium, and iridium, and these metals are adsorbed on the cation exchange membrane in the form of metal ions.

Although the form of the metal ion is not particularly limited, in the present invention, it is preferable to adsorb it on the cation exchange membrane in the form of an ammine complex ion.

As a specific method for ion exchange adsorption of metal ions belonging to the platinum group onto a cation exchange membrane, for example, an alkaline aqueous solution containing a salt of a metal belonging to the platinum group is maintained at room temperature to high temperature, and the cation exchange membrane is Just soak it.

More specifically, salts of metals belonging to the platinum group include chlorides, sulfates, nitrates, perchlorates, chloroammonium salts, etc. of metals such as platinum, rhodium, ruthenium, palladium, and iridium. , such a metal salt is usually added to an alkaline aqueous solution at a concentration of O, 0001 to 0.1 mol/l.
．． Preferably, it is blended in a concentration of 0.01 to 0.05 mol/l.

As the alkaline aqueous solution, ammonia water is usually used in order to convert the metal salt into an ammine complex ion form.

The ammonia water used usually has a concentration of 0.1 to 5% by weight, preferably 0.5 to 2% by weight.

When a chloroammonium salt is used as the metal salt, the metal ion can exist in the form of an ammine complex ion without using aqueous ammonia as the alkaline aqueous solution. It is also possible in the present invention to use other known aqueous alkaline solutions within the pH range.

In the present invention, it is essential to maintain the alkaline aqueous solution at room temperature to high temperature, and the temperature is usually room temperature to about 90°C, preferably 60 to 80°C.

If the temperature is lower than room temperature, it becomes difficult for metal ions to be adsorbed on the cation exchange membrane, making it difficult to obtain a desired electrolytic assembly with excellent adhesiveness, durability, and the like.

Further, if the temperature is higher than 90°C, ammonia etc. will evaporate and the composition of the alkaline aqueous solution will change, which is not preferable.

To give a specific example of the operation of immersing a cation exchange membrane in an alkaline aqueous solution, for example, the cation exchange membrane is sandwiched between cells,
When the exchange membrane is a large membrane, it is preferable to further attach a holder and then add an alkaline aqueous solution maintained at room temperature to high temperature to the compartment of the cell.

When two or more metal ions are to be adsorbed onto the cation exchange membrane, it is advisable to add salts of the two or more metals to the alkaline aqueous solution used.

Furthermore, by adding an alkaline aqueous solution containing salts of different metals to one side of each compartment of the cell, a cation exchange membrane in which different metal ions are adsorbed on both sides can be obtained.

The cation exchange membrane is usually immersed in an alkaline aqueous solution for about 30 to 90 minutes, so that about 0.5
A cation exchange membrane with metal ions adsorbed to a thickness of ~2μ is produced.

In the present invention, the cation exchange membrane on which metal ions have been adsorbed is then treated with an aqueous boron hydride salt solution to reduce the metal ions (reduction step).

In the present invention, treatment with a boron hydride salt aqueous solution is an essential requirement.

Therefore, even if the cation exchange membrane is treated with other known reducing agents, such as hydrazine, hydroxyamine, dimethylamine borane, etc., the metal ions are not reduced, or even if they are reduced, the adhesion remains. A metal layer with good properties cannot be formed on the inner surface of the cation exchange membrane, and as a result, the electrolytic assembly which is the intended object of the present invention cannot be manufactured at all.

Examples of boron hydride salts include sodium borohydride, potassium borohydride, and ammonium borohydride.

The pH of the boron hydride salt aqueous solution used in the present invention is 10 to
It is preferable to adjust it within the range of 12.

When the pH of the boron hydride salt aqueous solution is higher than 12, metal ions adsorbed on the cation exchange membrane are desorbed, making it difficult to form a metal layer on the inner surface of the exchange membrane.

Furthermore, if the pH of the boron hydride salt aqueous solution is lower than 10, the rate at which metal ions are reduced to metal particles becomes slow, making it impractical.

The pH of the boron hydride salt aqueous solution should be adjusted in such a way that the metal ions adsorbed on the cation exchange membrane will not be desorbed, or the catalytic ability of the cation exchange membrane surface and the bonded metal itself will not be impaired. It is preferable to use a base such as

Examples of such bases include aqueous ammonia and sodium borate IJ.
A pH buffer of 100 ml and sodium hydroxide is suitable.

The concentration of the boron hydride salt to be present in the boron hydride salt aqueous solution is not particularly limited and can be appropriately selected within a wide range, but is usually 0.02 to 2 mol/l, preferably 0.05 to 2 mol/l. It is preferable to set it to 0.5 mol/l.

A specific example of treating a cation exchange membrane on which metal ions have been adsorbed with a boron hydride salt aqueous solution is, for example, by immersing the cation exchange membrane in a boron hydride salt aqueous solution.

At this time, the hydrogenated boric acid aqueous solution is usually kept at room temperature to about 60°C, preferably 40 to 50°C, and the immersion time is generally about 30 to 90 minutes.

In this way, a cation exchange membrane is produced in which a metal layer is formed on the inner surface of the cation exchange membrane to a thickness of about 0.5 to 2 microns.

In the present invention, the metal layer is formed on the inner surface of the cation exchange membrane, so that the metal layer and the cation exchange membrane are bound together by a very strong bonding force due to the anchor effect.

In addition, the metal layer exhibits metallic luster and already has sufficient electrical conductivity, and in this respect it is essentially different from the activation layer formed by sensitization treatment in conventional plastic plating. There is.

In the present invention, the cation exchange membrane obtained above with a metal layer embedded in its inner surface is further brought into contact with an alkaline aqueous solution containing a salt of a metal belonging to the platinum group and a dialkylamine borane (Kaicho step).

As the salt of the metal belonging to the platinum group, any of the metal salts described in the above adsorption step can be used, and such metal salt is added in an alkaline aqueous solution, usually 0.0001 to 0.1 mol/l, preferably 0.0001 to 0.1 mol/l, preferably 0. It is preferable to blend it so that it is present at a concentration of 0.01 to 0.05 monole/l.

Further, examples of the dialkylamine borane include dimethylamine borane, diethylamine borane, etc., and the dialkylamine borane is usually added in an alkaline aqueous solution of 0.05 to 0.5 mol/L, preferably 0.1 to 0.5 mol/L.
It is preferable to blend it so that it is present at a concentration of 0.2 mol/l.

p of the alkaline aqueous solution used in this growth process.
H is not particularly limited as long as it is within the range of 8 to 13, and the pH may be appropriately selected depending on the type of metal bonded to the cation exchange membrane.

The pH is normally adjusted using a buffer solution consisting of aqueous ammonia or borate and alkali hydroxide.

In the growth process, it is essential to use dialkylamine borane as a reducing agent. By using dialkylamine borane, the inner part of the cation exchange membrane can be removed without using an inhibitor like in conventional chemical plating. The metal layer formed on the surface is selectively stretched to form a good metal layer that is firmly bonded to the surface of the metal layer.

At this time, boron hydride salt was used instead of dialkylamine borane.
Even when treated with an alkaline aqueous solution containing other reducing agents such as hydrazine, selective elongation does not occur on the surface of the metal layer formed on the inner surface of the cation exchange membrane. The metal layer cannot be controlled.

A specific example of contacting a cation exchange membrane with a metal layer embedded in the inner surface with an alkaline aqueous solution containing a salt of a metal belonging to the platinum group and a dialkylamine borane is, for example, when the cation exchange membrane is placed in a cell. It is better to add scissors and then an aqueous alkaline solution kept at high temperature to the compartment of the cell.

The amount of the alkaline aqueous solution added may be appropriately determined depending on the thickness of the metal layer to be grown.

Under optimal conditions, the reduction reaction proceeds selectively at the metal surface by autocatalysis and continues until most of the metal ions present in the alkaline aqueous solution are consumed.

The alkaline aqueous solution brought into contact with the cation exchange membrane is usually heated to 60 to 90°C, preferably 70 to 80°C.

The contact time between the cation exchange membrane and the alkaline aqueous solution is usually about 30 to 90 minutes, and thus the electrolysis assembly of the present invention in which the metal layer with a thickness of 2 to 5 μm is bonded to the cation exchange membrane is manufactured. be done.

The electrolytic assembly of the present invention produced by the above method is washed with water and acid (for example, hydrochloric acid) according to a conventional method, and then stored in water.

The bonded metal layer obtained by the method of the invention has uniformly distributed micropores, is flexible and has very strong adhesive properties.

Therefore, gas release during electrolysis is good, and IOOA/d
Even after operating for more than 1,000 hours at a high current density of m2 or more, the metal layer does not fall off at all.

Below are examples of actual planes and comparative examples.

Actual example 1 Using two L-shaped glass tubes (inner diameter 16 mm) with flanges of 161 mm, 7 L, and 50 mm in inner diameter, fit the flanges together, pack with silicone rubber, and use Nafion 125 membrane with a diameter of 30 mm [manufactured by DuPont]. , cation exchange membrane, equivalent weight EW=1200, membrane thickness 5 mils (approximately 0.1
25mm)) were sandwiched together to assemble Metsukicell.

Prior to bonding, the naphion membrane was boiled in 2N-HCl for 30 minutes, then washed with water, boiled in water for 30 minutes, and stored in water, and set in a wet state when used.

Bonding was performed according to the following steps unless otherwise specified.

Membrane → HCl treatment → water washing → adsorption → water washing → reduction → water washing → Kaicho → water washing → HC7 treatment → hot water treatment → water washing → conjugate.

The following bath solution was used for platinum bonding.

Adsorption bath platinum chloride ptcl4 o. i5g ammonia water (28%) 2ml water
15mlpH
11.5 adsorption is L7ml in each L type cell! Place them in a thermostatic water bath at 80℃ for 4 hours.
It was held for 0 minutes.

Reduction bath Sodium borohydride 0.1g Ammonia water (28%) 2ml Water 15wl
For 1 reduction, put 17 ml of the above bath solution into each compartment of the cell.
It was held at 0°C for 30 minutes.

Growth bath Platinum chloride PtC740.0 2 g Ammonia water (28%) 2 ml Dimethylamine borane (5% water soluble i) 2 ml water
Add 17TILl each of the above bath solutions to 13I71L, and heat at 80℃ for 30
Hold for minutes.

Under these treatment conditions, platinum did not precipitate in the bath solution, but selectively precipitated on the bonded metal surfaces.

Through the above treatment, platinum with a diameter of 1.6 μm and a thickness of 5 μm was bonded to both sides of the membrane.

Actual Example 2 Using the same cell as Actual Example 1, a Nafion 120 membrane [film thickness 10 mils (approximately 0.251n11L)] was pretreated in the same manner as Actual Example 1, and one side was coated with platinum and the other side was coated with rhodium. Joined.

The bath solution on the platinum side was prepared in the same manner as in Example 1.

The bath liquid on the rhodium side had the following composition.

Adsorption bath Rhodium chloride Rh (J! 30.0 2 g Ammonia water (28%) 2 ml water
15TIll adsorption is 80℃
, went for 60 minutes.

Reduction bath Sodium borohydride 0.05g Ammonia water (28%) 2ml water
15TLl reduction is 6
The test was carried out at 0°C for 60 minutes.

Growth bath Rhodium chloride Rh (J?30.0 2 g Ammonia water (28%) 2 ml Dimethylamine borane (5% aqueous solution) 1 ml water
14TLl Kaicho went to 75°C1 for 60 minutes.

Rhodium precipitation progressed selectively on the metal surface.

After treatment, bonded bodies of platinum and rhodium with a thickness of 5μ and 4μ were obtained.

Actual Winding Example 3 Using a cell similar to Actual Winding Example 1, platinum was bonded to one side of Nafion 125 and iridium was bonded to the other side.

The treatment bath for platinum was the same as in Example 1, and the treatment bath for iridium was as follows.

Adsorption bath Iridium ammonium chloride (NH4)2 Ir
Cl 60.1g Ammonia water ITLl water
15mlp
H 10.5
Adsorption was carried out at 80°C for 60 minutes.

Reduction bath pH buffer 0. IN-NaOH pH1 0.5'0.
1 M/ 11 H3 B04 1 2 m
il sodium borohydride (0.5% solution) Five-step reduction was carried out at 40°C for 60 minutes.

Growth bath Iridium chloride I rcl) 40.0 5 9 pH buffer (0.IN NaOH 10.11VL4?H3BO4
) pH 12.515 ml dimethylamine borane (5% solution) 1 ml was heated at 75° C. for 30 minutes.

The iridium precipitation loss in the growth bath was 0. It was less than 5 m9.

By the above treatment, a bonded body in which platinum and iridium were bonded at 5μ and 3μ was obtained.

Actual Flame Example 4 Using a cell similar to Actual Planer Example 1, an alloy of platinum and rhodium was joined.

Adsorption bath platinum chloride r'tcl! 4 o. i g Rhodium chloride RhCl30.0 5 g Ammonia water (28%) 2 ml water
151nl adsorption was carried out at 80°C for 145 minutes.

The reduction bath and operation were carried out in the same manner as in Actual Flame Example 1.

Long bath Platinum chloride PtCl40.0 2 g Rhodium chloride RhC730.0 2 g p I {Buffer pH1 1.0
(0.IN NaOH+0.1MAFI3BO4)
15ml dimethylamine borane (5% aqueous solution)
Growth of 2 ml was carried out at 80° C. for 60 minutes.

After treatment, a bonded body with a bonding layer of 4μ on both sides was obtained.

The electrode thickness was measured from the cross section of the bonded body obtained in each practical example by observation using an electron microscope.

The results are shown in Table 1.

Actual example 5 Nafion 117 membrane (E
W = 1100, film thickness 7 mil (0.175 ㆋ)],
The platinum adsorption temperature was varied.

Using the same adsorption solution as in practical example 1, 1
After adsorption for 2 hours, the platinum conjugate was then treated in the same manner as in actual case 1 to obtain a platinum conjugate.

The properties and electrolytic performance of the obtained bonded body were similar to those of Example 1.

Practical Strengthening Example 6 A Nafion 117 membrane was sandwiched between the same Metxcel as in Practical Winding Example 1, and the platinum adsorption liquid of Practical Practical Example 1 was placed on one side and the rhodium adsorption liquid of Practical Practical Example 2 was placed on the other. ) for 15 hours for adsorption, and then treated in the same manner as Example 2 to obtain a platinum-one-film-one-rhodium conjugate.

This bonded body showed the same performance as the bonded body obtained in Actual Flame Example 2.

Practical Example 7 A Nafion 117 membrane was sandwiched in the same Metxel as in Practical Example 1, and the platinum adsorption solution from Practical Flame Example 1 was added, and the mixture was heated at 25°C and 50°C.
．． The platinum adsorption rates when adsorbed at 60°C and 80°C were compared.

The time required to reach an adsorption amount of 1,0/d for platinum is 12 hours (25°G), 8 hours (50'C), and 4 hours, respectively.
r (600C) and lhr (800G).

Comparative Example I A zygote was obtained according to the method described in USP No. 3,432,355.

That is, platinum black powder was mixed with a tetrafluoroethylene dispersion (manufactured by DuPont, Teflon 30J), coated on aluminum foil, sintered at 350°C for 30 minutes, and then the aluminum foil was dissolved and removed with an aqueous alkaline solution.

The resulting thin film was thermocompression bonded to both sides of Nafion 125, which had been thermally stabilized in advance, to obtain a bonded body.

This thin film had a thickness of 60 μm, platinum black was present at a ratio of 7 m 9 /1, and the content of tetrafluoroethylene was 20% by weight.

Comparative Example 2 A bonded body was obtained according to the method described in JP-A-55-38934.

That is, a 3% chloroplatinic acid aqueous solution was used as the metal salt solution, and a 5% sodium boron hydride aqueous solution was used as the reducing agent.

A reducing agent was infiltrated from the back side of the naphion and platinum was deposited on the metal salt solution side to obtain a bonded body.

Platinum was present at a ratio of 7 .mu./-, and the thickness of the platinum layer was 10 .mu.m.

The bonded body obtained in Actual Plane Example 1, Comparative Example 1, or Comparative Example 2 was sandwiched between titanium electrodes via a platinum mesh to assemble a cell, and the cell was placed in pure water kept at 75°C for electrolysis. In this case, the current density and voltage change in one tank was measured.

The results obtained are shown in FIG. In Figure 1, curve A
is a graph for the joined body obtained in Comparative Example 1, curve B is for the joined body obtained in Comparative Example 2, and curve C is for the joined body obtained in Practical Example 1.

Further, the internal resistance of the above bonded body was measured by the current inruptor method (90'C) using the same cell as above.

As a result, the internal resistance of the zygote obtained in actual vertebra example 1 was 0.2
The internal resistance of the bonded body obtained in Comparative Example 1 was 0.35Ω-a, and the internal resistance of the bonded body obtained in Comparative Example 2 was 0.20Ω-a.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between cell voltage and current density for three types of bonded bodies.

Claims (1)

[Claims] 1. A method in which metal ions belonging to the platinum group are ion-exchanged and adsorbed onto a cation exchange membrane at room temperature to high temperature, and then treated with an aqueous boron hydride solution to deposit a metal layer on the inner surface of the membrane. ,
A method for producing a bonded body for electrolysis, characterized in that the membrane is subsequently brought into contact with an alkaline aqueous solution containing a salt of the metal and a dialkylamine borane to grow a metal layer on the membrane surface. 2. The method according to claim 1, wherein the cation exchange membrane is a perfluorinated hydrocarbon resin membrane having a sulfonic acid group or a carboxylic acid group. 3. The method according to claim 1 or 2, wherein the metal ion is a cation in the form of an ammine complex ion. 4. The method according to any one of claims 1 to 3, wherein the ion exchange adsorption is carried out at room temperature to 90°C. 5. The method according to any one of claims 1 to 3, wherein the ion exchange adsorption is carried out at 60 to 80°C. 6. The method according to any one of claims 1 to 5, wherein p I{ of the boron hydride salt aqueous solution is 10 to 12. 7. The method according to any one of claims 1 to 6, wherein the thickness of the metal layer deposited on the inner surface of the cation exchange membrane is 0.5 μm or more. 8. A method according to any one of claims 1 to 7, wherein the salt of the metal is in the form of a chloride, sulfate, nitrate, perchlorate or chloroammonium salt.