JP2019210541A - Method of manufacturing electrode for generating hydrogen and electrolysis method using electrode for generating hydrogen - Google Patents

Abstract

To provide a method of manufacturing an electrode for generating hydrogen which has sufficiently low initial hydrogen overvoltage and can easily provide an electrode for generating hydrogen with excellent durability.SOLUTION: In the method of manufacturing an electrode for generating hydrogen, a catalytic layer containing platinum carried on a conductive base material is brought into contact with an aqueous solution having pH of 2.5 to 4.0 and ORP of 100 mV or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an electrode for hydrogen generation used for electrolysis of water or electrolysis of an aqueous solution of an alkali metal chloride such as salt, and an electrolysis method using the electrode for hydrogen generation.

  The water or alkali metal chloride aqueous solution electrolysis industry is a power-intensive industry, and various technological developments have been made to save energy. The energy saving means is to reduce power loss generated during electrolysis by reducing electrolysis voltage and / or improving current efficiency. For example, in the salt electrolysis industry, the current efficiency is operated at 95% or more, and there is little room for improvement. On the other hand, the electrolysis voltage is operated at around 3.0 V with respect to the theoretical decomposition voltage of about 2.3 V, and there is a lot of room for voltage reduction, and research and development for reducing the voltage are actively conducted.

  Among them, many proposals have been made so far regarding a hydrogen generating electrode for reducing cathode overvoltage, so-called active cathode, and in recent years, an active cathode comprising a catalyst layer containing platinum supported on a conductive substrate has been proposed. Yes.

  For example, Patent Document 1 proposes an electrode for hydrogen generation “a platinum alloy of platinum and a transition metal element supported on a conductive base material”.

  Patent Document 2 proposes an electrode for hydrogen generation “having a catalyst layer mainly composed of platinum, nickel and palladium supported on a conductive substrate”.

  Each of these hydrogen generating electrodes has excellent characteristics that a sufficiently low hydrogen overvoltage performance can be obtained over a long period of time, and contributes to energy saving in the electrolytic industry of water or an aqueous alkali metal chloride solution.

  However, each of the hydrogen generating electrodes is subjected to “electrochemical reduction treatment in water or an aqueous alkali metal chloride solution” in the production process, but the electrochemical reduction treatment sometimes obtains the original characteristics. There were cases where it was not possible. That is, a hydrogen generation cathode composed of a catalyst layer containing platinum supported on a conductive substrate manufactured by electrochemical reduction treatment, and may exhibit a hydrogen overvoltage performance higher by 5 to 30 mV than the original. There is a need for a method for producing an electrode for hydrogen generation that can stably obtain the original low hydrogen overvoltage performance.

Japanese Patent Laying-Open No. 2005-330575 JP2015-143389A

  An object of the present invention is to generate hydrogen comprising a catalyst layer containing platinum supported on a conductive substrate, which can be used in water or alkali metal chloride aqueous solution electrolysis industry, etc., and can stably obtain low hydrogen overvoltage performance. It is in providing the manufacturing method of the electrode for a vehicle.

  In order to solve the above-mentioned problems, the inventor has intensively studied a method for producing an electrode for hydrogen generation comprising a catalyst layer containing platinum supported on a conductive substrate. It has come. That is, the present invention provides a hydrogen generation characterized by bringing a catalyst layer containing platinum supported on a conductive substrate into contact with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. It is a manufacturing method of the electrode for a vehicle.

  Hereinafter, the present invention will be described in detail.

  The method for producing an electrode for hydrogen generation according to the present invention comprises contacting a catalyst layer containing platinum supported on a conductive substrate with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. Is essential.

  It is essential that the aqueous solution used in the present invention has a pH of 2.5 to 4.0. When the pH is less than 2.5, the conductive substrate is corroded or the catalyst layer is dropped, and the effect of the present invention cannot be obtained. In addition, when the pH exceeds 4.0, low overvoltage performance cannot be stably obtained. Preferably pH is 2.9-3.5, More preferably, pH is 2.9-3.3. In addition, what is necessary is just to measure pH of aqueous solution with a commercially available pH meter.

  In the present invention, the method is not limited as long as the pH of the aqueous solution can be adjusted to 2.5 to 4.0. A so-called acid may be added in an appropriate amount. For example, one or more organic acids such as mineral acids such as hydrochloric acid, nitric acid and sulfuric acid, and formic acid, acetic acid, citric acid, aspartic acid, ascorbic acid and erythorbic acid are added to water, and the pH is adjusted to 2.5-4. 0.0.

  It is essential that the aqueous solution used in the present invention has a redox potential, that is, ORP of 100 mV or less. When ORP exceeds 100 mV, low overvoltage performance cannot be stably obtained. The ORP is preferably 50 mV or less. There is no lower limit for ORP. In addition, what is necessary is just to measure ORP of aqueous solution with a commercially available ORP meter.

  In the present invention, the method is not limited as long as the ORP of the aqueous solution can be 100 mV or less. For example, when the acid is added to water and the pH is adjusted to 2.5 to 4.0, if the ORP is 100 mV or less, it can be used in the present invention as it is.

  However, since the ORP usually exceeds 100 mV, for example, an appropriate amount of a so-called reducing agent is added to adjust the ORP to 100 mV or less. For example, a reducing agent such as sodium ascorbate, hydrazine, sodium sulfite, or sodium erythorbate may be added to make ORP 100 mV or less. As another method of adjusting the ORP to 100 mV or less, for example, an inert gas such as nitrogen or argon can be blown. Of these methods of adjusting the ORP to 100 mV or less, a method of adding a reducing agent is preferable from the viewpoint of cost.

  As described above, an acid and / or a reducing agent is added to water to produce an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less, and the aqueous solution is supported on a conductive substrate. What is necessary is just to make it contact the catalyst layer containing platinum.

  There is no particular limitation on the method for bringing the catalyst layer into contact with the aqueous solution. For example, the aqueous solution may be placed in a suitable container, and the conductive base material on which the catalyst layer is supported may be placed therein for a certain period of time.

  The temperature of aqueous solution should just exceed melting | fusing point of aqueous solution and is less than a boiling point. Since the reducing agent may be decomposed when the temperature is high, it is preferably 40 ° C. or lower, more preferably 10 to 35 ° C., so-called room temperature, and no special heating or cooling is required.

  Although there is no special restriction | limiting in time to contact with aqueous solution, in order to demonstrate the effect of this invention more, 1 hour or more is preferable. Moreover, in order to prevent corrosion of a base material, 240 hours or less are preferable. Especially preferably, it is 10 hours or more and 48 hours or less.

  It is essential that the catalyst layer used in the present invention contains platinum. By including platinum, it is possible to produce an electrode for hydrogen generation with an extremely low overvoltage during hydrogen generation. Preferably, the catalyst layer contains at least one of nickel and palladium, and particularly preferably, the catalyst layer contains platinum, nickel and palladium.

  It is essential that the catalyst layer is supported on a conductive substrate. Examples of the material of the conductive substrate used include nickel, iron, copper, titanium, and stainless steel alloy, and nickel having excellent corrosion resistance against an alkaline solution is particularly preferable.

  The shape of the conductive substrate is not particularly limited, and may generally be a shape that matches the electrode of the electrolytic cell. For example, a flat plate, a curved plate, or the like can be used.

  In addition, the conductive substrate used is preferably a perforated plate, and for example, expanded metal, punching metal, nets, and the like can be used.

  The method for supporting the catalyst layer on the conductive substrate is not particularly limited, and the conventional method described in Patent Document 1 or Patent Document 2 (a liquid containing a catalyst component is applied to the substrate and thermally decomposed) is used. May be used as appropriate. The composition of the catalyst layer is not particularly limited, and is a conventional composition described in Patent Document 1 or Patent Document 2 (a platinum alloy of platinum and a kind of transition metal element selected from the group of nickel, cobalt, copper, silver, and iron) The platinum content in the platinum alloy is preferably in the range of 0.40 to 0.99 in molar ratio, or the catalyst layer mainly composed of platinum, nickel and palladium). .

  In the method of supporting the catalyst layer, for example, a catalyst layer forming solution containing platinum can be applied on the conductive substrate, dried, and thermally decomposed to form the catalyst layer on the conductive substrate. The catalyst layer forming liquid may contain one or both of nickel and palladium. Examples of the thermal decomposition include 350 to 500 ° C. and 5 to 60 minutes. The series of operations of application, drying, and thermal decomposition may be repeated a predetermined number of times, for example, 2 to 15 times.

  The catalyst layer forming solution can be prepared by, for example, dissolving a platinum compound, a nickel compound, or a palladium compound in a solvent.

  Examples of the platinum compound used for preparing the catalyst layer forming liquid include platinum salts such as chloroplatinic acid and dinitrodiamine platinum. In particular, it is preferable to use dinitrodiammine platinum that forms an ammine complex because the crystallite diameter of the platinum alloy after the reduction treatment can be reduced to, for example, 200 angstroms or less to increase the reaction specific surface area. This is because the dinitrodiamine platinum has a high thermal decomposition temperature of about 550 ° C., and thus aggregation of platinum during thermal decomposition is suppressed.

  The nickel compound and palladium compound used for the preparation of the catalyst layer forming liquid are preferably a material that is soluble in a solvent because the composition of the catalyst layer tends to be uniform and the surface area of the support is easily increased. Nickel salt, nickel fine particles, palladium salt, palladium fine particles and the like. Examples of the salt in the nickel salt and the palladium salt include nitrates, sulfates, chlorides, carbonates, acetates, sulfamates, and the like.

  The solvent is preferably one in which a platinum compound, a nickel compound and a palladium compound can be completely dissolved, an inorganic acid such as water, nitric acid, hydrochloric acid and sulfuric acid, an organic solvent such as methanol, ethanol, propanol, butanol and acetic acid, or a mixture thereof. Can also be used. In addition, the pH of the catalyst layer forming solution may be adjusted and used for the purpose of suppressing dissolution of the base metal in the coating solution, and complex salts such as lysine and citric acid may be added to increase the surface area of the support. Nickel and palladium may be complexed.

  The composition (ratio of platinum, nickel and palladium) of the catalyst layer formed by the method for producing the electrode for hydrogen generation of the present invention is determined by the composition of the catalyst layer forming solution. What is necessary is just to adjust palladium to the same composition as the catalyst layer of the electrode for hydrogen generation desired. Moreover, the metal component concentration of the catalyst layer forming liquid is not particularly limited. For example, if the platinum concentration is 40 to 80 g / L and nickel and palladium are in a desired ratio with respect to platinum. Good.

  The conductive substrate is preferably roughened in advance. This is because the contact surface area can be increased by roughening, and the adhesion between the substrate and the support is improved. The surface roughening means is not particularly limited, and a known method such as sand blasting, etching with oxalic acid or hydrochloric acid solution, washing with water, drying and the like can be used.

  The method for applying the catalyst layer forming liquid to the conductive substrate is, for example, conducting a platinum salt, and if necessary, a catalyst layer forming liquid containing a nickel salt and a palladium salt using a brush or the like. It may be applied to a conductive substrate. In addition to brush coating, all known methods such as a spray method and a dip coating method can be suitably used.

  What is necessary is just to perform the drying temperature after application | coating at the temperature of 200 degrees C or less for 5 to 60 minutes, for example, and the drying temperature of 150 degrees C or less is preferable.

  The thermal decomposition temperature after drying may be, for example, in the range of more than 200 ° C. and not more than 700 ° C. for 5 to 60 minutes, preferably in the range of more than 350 ° C. and not more than 500 ° C. For example, when a dinitrodiamine platinum solution is used, the thermal decomposition temperature of dinitrodiamine platinum is 550 ° C., and by performing thermal decomposition at 500 ° C. or less, platinum sintering is suppressed and hydrogen overvoltage is further reduced. A working electrode can be obtained.

In the present invention, the coating amount and the number of coatings of the catalyst layer forming liquid are not particularly limited. For example, the coating is performed by controlling the coating amount to 13 to 31 mL / m ² per projected area of the conductive substrate, and then drying and pyrolyzing. The process may be repeated 4 to 8 times, and the final catalyst layer weight may be 10 g / m ² or more. The weight of the catalyst layer is preferably 12 g / m ² or more, and more preferably 14 g / m ² or more.

  Further, the catalyst layer forming solution may be applied only to one side of the substrate, but it is preferably applied to both sides particularly when the substrate is a perforated plate.

  In the present invention, after the application, drying, and thermal decomposition, baking may be performed at 300 to 500 ° C. for 0.2 to 8 hours.

It is preferable to perform a reduction treatment for the purpose of reducing and alloying the catalyst layer formed on the conductive substrate by the above-described method or the like into a metal state. Although the reduction treatment method is not particularly limited, for example, a chemical reduction method by contact with a substance having a strong reducing power such as hydrazine, formic acid or oxalic acid, an electrochemical reduction method for giving a reduction potential to platinum, nickel and palladium, etc. Can be used. Preferably, an electrochemical reduction method used for the cathode when electrolyzing water or an aqueous alkali metal chloride solution is preferable. The “electrolysis of water” in the present invention means not “electrolysis of pure water” but “electrolysis of water containing an electrolyte such as NaOH, KOH, HCl, H ₂ SO ₄ ”. For example, if a catalyst layer containing platinum supported on the conductive substrate is attached as a cathode to an ion exchange membrane salt electrolysis tank and salt electrolysis is performed, the catalyst layer is electrochemically reduced.

  There is no restriction | limiting in particular in salt electrolysis conditions, What is necessary is just to apply the electrolysis conditions of ion exchange membrane method salt electrolysis as it is. For example, it may be carried out at a temperature of 70 to 90 ° C. and an electrolytic current density of 1 to 10 kA / m 2, preferably a temperature of 80 to 88 ° C. and an electrolytic current density of 3 to 8 kA / m 2. There is no particular limitation on the reduction time of the catalyst layer, but it may be continued for 3 minutes or more, and there is no upper time limit.

  Although the electrodes for generating hydrogen described in Patent Document 1 and Patent Document 2 exhibit excellent performance, when manufactured by a conventional manufacturing method, an overvoltage exceeding 80 mV may be exhibited in some cases. However, by applying the production method of the present invention (Claim 1), an electrode for hydrogen generation that exhibits an excellent overvoltage of less than 80 mV can be easily obtained.

  Although the cause which may show the overvoltage exceeding 80 mV is not necessarily clear in the conventional manufacturing method, it is assumed that it may be poisoned with iron etc. at the time of the said reduction process. For this reason, after performing electrochemical reduction, the process of removing poisoning substances without dropping off the catalyst is essential. The catalyst layer comprising platinum supported on a conductive substrate, which is a production method of the present invention, and an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less are brought into contact with each other. It is estimated that poisonous substances will be removed without dropping off.

  Accordingly, in the present invention, after performing an electrochemical reduction treatment in water or an aqueous alkali metal chloride solution, the catalyst layer is brought into contact with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. Is preferred. As described above, the reduction time of the catalyst layer may be continued for 3 minutes or more. The reduction treatment is stopped in 3 minutes, and then the aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less is combined with the catalyst layer. May be contacted.

  Moreover, even if the catalyst layer containing platinum supported on the conductive substrate is used as a cathode for electrolysis of water or an aqueous alkali metal chloride solution for a certain period of time, the pH is 2.5 to The effect of the present invention can be obtained by contacting with an aqueous solution having an ORP of 100 mV or less at 4.0. This catalyst layer may be the one after the electrochemical reduction treatment of the catalyst layer described above, or may be the one without the electrochemical reduction treatment. Further, the catalyst layer may be subjected to an electrochemical reduction treatment before or after being brought into contact with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. Good. For example, after the reduction of the catalyst is completed, after being used as a cathode for electrolysis of water or an aqueous alkali metal chloride solution for 4 to 8 years, an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less By contacting the catalyst layer, a hydrogen generation electrode having a hydrogen generation overvoltage of less than 80 mV can be obtained.

  When the catalyst layer containing platinum supported on the conductive substrate is brought into contact with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less, the catalyst layer is subjected to water or alkali metal chloride. The effect of this invention can be acquired by removing from the electrolysis cell used for the electrolysis of aqueous solution of matter, and making it contact with aqueous solution whose pH is 2.5-4.0 and ORP is 100 mV or less. As another method, the catalyst layer containing platinum supported on the conductive substrate was mounted as a cathode without removing the catalyst layer from the electrolysis cell used for electrolysis of water or an aqueous alkali metal chloride solution. In the state, the effect of the present invention can also be obtained by contacting with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. When it is not removed from the electrolysis cell, it is not necessary to remove or reattach the catalyst layer containing platinum supported on the conductive substrate from the electrolysis cell, and the cathode can be manufactured more easily.

  For example, an electrolytic cell is assembled using a vinyl sheet as a diaphragm in a state where a catalyst layer containing platinum supported on the conductive substrate is mounted as a cathode, and the pH is 2.5 to 4.0 in the cathode chamber. Thus, if the ORP is filled with an aqueous solution of 100 mV or less, it is possible to contact the catalyst layer with an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less.

  Further, for example, in a state where a catalyst layer containing platinum supported on the conductive substrate is mounted as a cathode, an electrolytic cell is assembled with two cathodes facing each other, and pH is set in the cathode chamber. Is 2.5 to 4.0 and ORP is filled with an aqueous solution of 100 mV or less, it is possible to contact the catalyst layer with an aqueous solution of pH 2.5 to 4.0 and ORP of 100 mV or less. is there.

  After the cathode is manufactured by the above method, the electrolytic cell is disassembled. For example, if an electrolytic cell is assembled using a cation exchange membrane as a diaphragm, and electrolysis of water or an aqueous solution of alkali metal chloride is performed, it is more than conventional. It is possible to carry out the electrolysis at a low voltage.

  The electrode for hydrogen generation of the present invention electrolyzes water or an alkali metal chloride aqueous solution, generates hydrogen gas and alkali metal hydroxide aqueous solution from the cathode, and generates oxygen gas or chlorine gas from the anode. When using as an electrode for hydrogen generation in an electrolysis characterized by the above, i.e., in an electrolytic cell in which an anode is disposed across a diaphragm, water or an alkaline metal chloride aqueous solution such as salt, a low hydrogen overvoltage is obtained. In addition, the low overvoltage characteristics can be stably maintained for a long time without special measures to prevent iron ions from being mixed into the catholyte, and the catalyst does not peel off or fall off during a stop or restart operation. It is an electrode for hydrogen generation that is extremely excellent in hydrogen overvoltage performance and durability. Here, the diaphragm typically includes a cation exchange membrane that selectively permeates cations.

  Therefore, in the field of electrolysis industry of an aqueous solution of alkali metal chloride such as water or sodium chloride, the electrode for hydrogen generation is simply changed to the electrode for hydrogen generation produced by the production method provided by the present invention. The required energy can be reduced.

  According to the present invention, it is possible to easily obtain an electrode for hydrogen generation having an initial hydrogen overvoltage that is sufficiently low and excellent in durability, and can greatly reduce the energy required for the electrolysis industry of water or an aqueous alkali metal solution. It is.

  The present invention will be specifically described by the following examples, but the present invention is not limited to the examples.

<Conductive substrate>
Nickel expanded metal was used as the conductive substrate. The nickel expanded metal was pretreated by etching with a 10 wt% hydrochloric acid solution at a temperature of 50 ° C. for 10 minutes, and then washing and drying.

<Preparation of catalyst layer forming liquid>
The catalyst layer forming liquid containing platinum and nickel is obtained by dissolving 8.94 g of nickel nitrate hexahydrate in 60 mL of a dinitrodiammine platinum nitric acid solution (manufactured by Tanaka Kikinzoku) with a platinum content of 100 g / L, and then using water. And made up to 100 mL (platinum: 50 mol%, nickel: 50 mol%).

  The catalyst layer forming solution containing platinum, nickel, and palladium is composed of dinitrodiammine platinum nitrate solution (made by Tanaka Kikinzoku) having a platinum content of 100 g / L in 60 mL of nickel nitrate hexahydrate and palladium nitrate dihydrate. 0.82 g (manufactured by Kojima Chemical Co., Ltd.) was dissolved and then made up to 100 mL with water (platinum: 48 mol%, nickel: 48 mol%, palladium: 4 mol%).

<Measurement of hydrogen generation overvoltage>
Water electrolysis was performed for 10 minutes under the conditions of Ni, temperature 88 ° C., and current density 6.0 kA / m ² using an electrolytic solution of 32 wt% sodium hydroxide aqueous solution (capacity: about 1 L) by the current interrupter method. The hydrogen generation overvoltage was measured.

<Measurement of pH>
The pH of the aqueous solution was measured by attaching a waterproof plastic pH electrode (9265-10D: manufactured by Horiba, Ltd.) to a portable pH meter (D-72: manufactured by Horiba, Ltd.).

<Measurement of ORP>
The ORP of the aqueous solution was measured by attaching a waterproof platinum composite ORP electrode (9300-10D: manufactured by Horiba, Ltd.) to a portable pH meter (D-72: manufactured by Horiba, Ltd.).

Example 1
Using the roller, the catalyst layer forming solution containing platinum and nickel (platinum: 50 mol%, nickel: 50 mol%) prepared in <Preparation of catalyst layer forming solution> is 1.2 m × 0.4 m. It is applied to one side of the nickel expanded metal at a coating amount of 10 mL / m ² , and subsequently applied to the other side of the nickel expanded metal at a coating amount of 10 mL / m ² , and is carried out at 80 ° C. for 10 minutes in a hot air dryer. After drying, it was pyrolyzed at 400 ° C. for 10 minutes under an air flow using a box-type baking furnace. This series of operations was repeated 6 times to form a catalyst layer on the conductive substrate.

  Next, 5 cm × 6 cm was cut out from the conductive base material on which the catalyst layer was formed by the above operation, and attached as a cathode of an ion exchange membrane method salt electrolysis cell. Both the anode and ion exchange membrane of the salt electrolysis cell were 5 cm × 6 cm.

  While supplying saturated brine to the anode chamber of the salt electrolysis cell and water to the cathode chamber, an electrolytic current of 18 A was applied to perform electrochemical reduction of the catalyst layer. At this time, the temperature of the cathode chamber and the anode chamber was 88 ° C., the sodium chloride concentration at the outlet of the anolyte was 200 g / L, and the sodium hydroxide concentration at the outlet of the cathode chamber was 33 wt%. Further, about 10 ppm of iron was present in the water supplied to the cathode chamber. Under the above conditions, salt electrolysis was continued for 8 days, the electrolysis cell was disassembled, and the conductive substrate on which the catalyst layer was formed was taken out.

  Next, 13.2 g of citric acid and 9.8 g of sodium ascorbate were dissolved in 500 mL of water. This solution had a pH of 3.1 and an ORP of 45 mV.

  The conductive substrate on which the catalyst layer having been subjected to electrochemical reduction is formed is immersed in an aqueous solution having a pH of 3.1 and an ORP of 45 mV, and the solution and the catalyst layer are placed at room temperature for 24 hours. The electrode for hydrogen generation was made to contact.

  Thereafter, the hydrogen generation overvoltage of the hydrogen generation electrode was measured and found to be 74 mV.

Comparative Example 1
A hydrogen generation electrode was produced in the same manner as in Example 1 except that an aqueous solution having a pH of 3.1 and an ORP of 45 mV was not brought into contact with the catalyst layer after the electrochemical reduction, and the hydrogen generation overvoltage was measured. As a result, it was 85 mV.

Example 2
Example except that an aqueous solution in which 36.0 g of ascorbic acid and 5.0 g of sodium ascorbate were dissolved in 500 mL of water was brought into contact with the catalyst layer instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV. The electrode for hydrogen generation was manufactured in the same manner as in Example 1 and the hydrogen generation overvoltage was measured. As a result, it was 75 mV.

  The aqueous solution had a pH of 3.2 and an ORP of 37 mV.

Example 3
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, an aqueous solution in which 37.5 g of erythorbic acid and 5.9 g of sodium erythorbate monohydrate are dissolved in 500 mL of water is brought into contact with the catalyst layer. Except for the above, a hydrogen generation electrode was produced in the same manner as in Example 1, and the hydrogen generation overvoltage was measured and found to be 71 mV.

  The aqueous solution had a pH of 3.2 and an ORP of 21 mV.

Comparative Example 2
Example except that an aqueous solution in which 0.67 g of ascorbic acid and 1.0 g of sodium ascorbate were dissolved in 500 mL of water was brought into contact with the catalyst layer instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV. The electrode for hydrogen generation was manufactured in the same manner as in Example 1 and the hydrogen generation overvoltage was measured. As a result, it was 84 mV.

  The aqueous solution had a pH of 4.3 and an ORP of 33 mV.

Comparative Example 3
An electrode for hydrogen generation as in Example 1 except that an aqueous solution in which 0.33 g of ascorbic acid was dissolved in 500 mL of water was brought into contact with the catalyst layer instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV. And hydrogen generation overvoltage was measured and found to be 81 mV.

  The aqueous solution had a pH of 3.4 and an ORP of 160 mV.

Comparative Example 4
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, 10% sulfuric acid was added dropwise to 500 mL, and an aqueous solution having a pH of 3.3 was brought into contact with the catalyst layer. The generation electrode was manufactured and the hydrogen generation overvoltage was measured and found to be 83 mV.

  The aqueous solution had a pH of 3.3 and an ORP of 255 mV.

Example 4
Instead of a catalyst layer forming solution containing platinum and nickel (platinum: 50 mol%, nickel: 50 mol%), for forming a catalyst layer containing platinum, nickel and palladium prepared in <Preparation of catalyst layer forming solution> A hydrogen generation electrode was produced in the same manner as in Example 1 except that the liquid (platinum: 48 mol%, nickel: 48 mol%, palladium: 4 mol%) was used, and the hydrogen generation overvoltage was measured. It was.

Comparative Example 5
An electrode for hydrogen generation was produced in the same manner as in Example 4 except that an aqueous solution having a pH of 3.1 and an ORP of 45 mV was not brought into contact with the catalyst layer after electrochemical reduction, and the hydrogen generation overvoltage was measured. As a result, it was 81 mV.

  From the results of Examples and Comparative Examples, when the production method of the present invention is applied, a low value of hydrogen generation overvoltage of 80 mV or less is obtained. However, if the production method of the present invention is deviated, the hydrogen overvoltage exceeds 80 mV. I understood that.

Example 5
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, an aqueous solution prepared by dissolving 20.8 g of erythorbic acid and 5.8 g of sodium erythorbate monohydrate in 500 mL of water is brought into contact with the catalyst layer. Except for the above, a hydrogen generation electrode was produced in the same manner as in Example 1, and the hydrogen generation overvoltage was measured and found to be 79 mV.

  The aqueous solution had a pH of 3.5 and an ORP of 63 mV.

Example 6
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, an aqueous solution prepared by dissolving 42.5 g of erythorbic acid and 3.3 g of sodium erythorbate monohydrate in 500 mL of water was used for 46 hours. A hydrogen generation electrode was produced in the same manner as in Example 1 except that it was brought into contact with the layer, and the hydrogen generation overvoltage was measured. As a result, it was 71 mV.

  The aqueous solution had a pH of 2.9 and an ORP of 52 mV.

Example 7
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, an aqueous solution prepared by dissolving 42.5 g of erythorbic acid and 1.7 g of sodium erythorbate monohydrate in 500 mL of water was used for 46 hours. A hydrogen generation electrode was produced in the same manner as in Example 1 except that it was brought into contact with the layer, and the hydrogen generation overvoltage was measured. As a result, it was 72 mV.

  The aqueous solution had a pH of 2.6 and an ORP of 42 mV.

Comparative Example 6
Instead of an aqueous solution having a pH of 3.1 and an ORP of 45 mV, a solution in which 42.5 g of erythorbic acid was dissolved in 500 mL of water was blown with nitrogen gas to adjust the ORP and contact the catalyst layer for 46 hours. A hydrogen generation electrode was produced in the same manner as in Example 1 except that the hydrogen generation overvoltage was measured, and the result was 81 mV.

  The aqueous solution had a pH of 2.3 after dissolution of erythorbic acid, and the ORP was adjusted from 110 mV to 98 mV by blowing nitrogen gas.

Example 8
Using the roller, the catalyst layer forming solution containing platinum and nickel (platinum: 50 mol%, nickel: 50 mol%) prepared in <Preparation of catalyst layer forming solution> is 1.4 m × 0.4 m. It is applied to one side of the nickel expanded metal at a coating amount of 10 mL / m ² , and subsequently applied to the other side of the nickel expanded metal at a coating amount of 10 mL / m ² , and is carried out at 80 ° C. for 10 minutes in a hot air dryer. After drying, it was pyrolyzed at 400 ° C. for 10 minutes under an air flow using a box-type baking furnace. This series of operations was repeated 6 times to form a catalyst layer on the conductive substrate.

Next, six conductive base materials on which the catalyst layer was formed by the above operation were attached as cathodes of an ion exchange membrane method salt electrolysis cell. Both the anode and the ion exchange membrane of the salt electrolysis cell had an area of 3.3 m ² .

  While supplying saturated salt water to the anode chamber of the salt electrolysis cell and water to the cathode chamber, an electrolytic current of 1 kA was applied to perform electrochemical reduction of the catalyst layer. Next, the current was increased to 16.4 kA, the temperature of the cathode chamber and the anode chamber was 88 ° C., the sodium chloride concentration at the anolyte outlet was adjusted to 200 g / L, and the sodium hydroxide concentration at the cathode chamber outlet was adjusted to 33 wt%. For 7 years. Next, the electrolytic cell was disassembled, and the conductive substrate on which the catalyst layer was formed was taken out.

  Next, 39.2 g of erythorbic acid and 6.2 g of sodium erythorbate monohydrate were dissolved in 500 mL of water. This solution had a pH of 3.2 and an ORP of 45 mV.

  5 cm × 6 cm was cut out from the electroconductive substrate on which the catalyst layer was taken out from the electrolysis cell, immersed in an aqueous solution having the pH of 3.1 and the ORP of 45 mV, and the liquid and The catalyst layer was brought into contact to produce a hydrogen generation electrode.

  Thereafter, the hydrogen generation overvoltage of the hydrogen generation electrode was measured and found to be 77 mV.

Comparative Example 7
A hydrogen generating electrode was produced in the same manner as in Example 8 except that an aqueous solution having a pH of 3.2 and an ORP of 45 mV was not brought into contact with the catalyst layer taken out from the electrolytic cell, and the hydrogen generation overvoltage was measured. As a result, it was 104 mV.

Example 9
A catalyst layer was formed on a conductive substrate in the same manner as in Example 8, and further, salt electrolysis was performed for 7 years in the same manner as in Example 8, and then the electrolytic cell was disassembled.

  Next, an electrolytic cell was assembled using a vinyl sheet as a diaphragm in a state where the catalyst layer supported on the conductive substrate was mounted as a cathode of the electrolytic cell.

Next, 150 kg of erythorbic acid and 20 kg of sodium erythorbate monohydrate were dissolved in 2 m ³ of water. This solution had a pH of 3.0 and an ORP of 43 mV.

  The cathode chamber of the electrolysis cell was filled with an aqueous solution having a pH of 3.0 and an ORP of 43 mV, and the solution and the catalyst layer were contacted at room temperature for 24 hours to produce a hydrogen generating electrode.

  The electrolytic cell was disassembled, and an electrolytic cell was assembled using a cation exchange membrane as a diaphragm. The current was 16.4 kA, the temperature of the cathode chamber and the anode chamber was 88 ° C., the salt concentration at the anolyte outlet was 200 g / L, the cathode When sodium chloride electrolysis was performed while adjusting the sodium hydroxide concentration at the chamber outlet to 32 wt%, the electrolysis voltage showed 2.97V.

Comparative Example 8
Instead of an aqueous solution having a pH of 3.0 and an ORP of 43 mV, a hydrogen generating electrode was prepared in the same manner as in Example 9 except that pure water having a pH of 7.2 and an ORP of 250 mV was brought into contact with the catalyst layer. Manufactured.

  The electrolytic cell was disassembled and an electrolytic cell was assembled using a cation exchange membrane as a diaphragm as in Example 9. The current was 16.4 kA, the temperature of the cathode chamber and the anode chamber was 88 ° C., and the sodium chloride at the anolyte outlet. When salt electrolysis was carried out while adjusting the concentration to 200 g / L and the sodium hydroxide concentration at the cathode chamber outlet to 32 wt%, the electrolysis voltage was 3.02 V, which was 50 mV higher than Example 9.

  In Example 9, the electrode for hydrogen generation was manufactured by the manufacturing method of the present invention, but in Comparative Example 8, it was different from the manufacturing method of the present invention. Since the other conditions were the same, the reason why the electrolysis voltage in Example 9 was as low as 50 mV compared to the electrolysis voltage in Comparative Example 8 was that the electrode for hydrogen generation produced in Example 9 was excellent. It can be said that it has performance.

  The electrode for hydrogen generation obtained by the production method of the present invention can be used for electrolysis of water or electrolysis of an aqueous solution of alkali metal chloride such as sodium chloride, and can be used in a wide range of electrolysis industries including the salt electrolysis industry. Have sex.

Claims (7)

A method for producing an electrode for hydrogen generation, comprising contacting a catalyst layer containing platinum supported on a conductive substrate and an aqueous solution having a pH of 2.5 to 4.0 and an ORP of 100 mV or less. The catalyst layer containing platinum supported on the conductive base material is one after being subjected to an electrochemical reduction treatment in water or an aqueous alkali metal chloride solution. Of producing an electrode for hydrogen generation. 3. The catalyst layer containing platinum supported on the conductive substrate is used after being used as a cathode for electrolysis of water or an aqueous alkali metal chloride solution. The manufacturing method of the electrode for hydrogen generation of description. The hydrogen generation according to any one of claims 1 to 3, wherein the catalyst layer containing platinum supported on the conductive substrate is mounted as a cathode of an electrolysis cell. For manufacturing an electrode. The production of an electrode for hydrogen generation according to any one of claims 1 to 4, wherein the catalyst layer containing platinum supported on the conductive substrate contains nickel and / or palladium. Method. The electrode for hydrogen generation obtained by the method for producing an electrode for hydrogen generation according to any one of claims 1 to 5 is used as a cathode, and water or an alkali metal is used in an electrolytic cell in which the anode is arranged with a diaphragm interposed therebetween. An electrolysis method comprising electrolyzing an aqueous chloride solution to produce hydrogen gas and an alkali metal hydroxide aqueous solution from the cathode, and producing oxygen gas or chlorine gas from the anode. The electrolysis method according to claim 6, wherein the diaphragm is a cation exchange membrane.