WO2020110527A1 - Hydrogen generation electrode, method of producing same, and hydrogen production method - Google Patents

Abstract

Provided is a hydrogen generation electrode in which it is possible to reduce overvoltage, as converted from the hydrogen generation potential of the hydrogen generation electrode, and in which reductions in effective platinum catalyst surface area, caused by reverse current when electrolysis is halted, can be effectively prevented.　The hydrogen generation electrode comprises a coating containing at least platinum, nickel oxide, and cerium oxide on an electrically-conductive base material.

Description

Hydrogen generating electrode, method for manufacturing the same, and method for manufacturing hydrogen

The present invention relates to a hydrogen generating electrode, a manufacturing method thereof, and a hydrogen manufacturing method.

　Reducing energy consumption is the most important issue in the ion-exchange membrane salt electrolysis process. When the cell voltage in the ion-exchange membrane salt electrolysis method is analyzed in detail, in addition to the theoretically required voltage, the voltage due to the membrane resistance of the ion-exchange membrane, the overvoltage of the anode and the cathode, the voltage due to the liquid resistance and the gas resistance are added. Of these voltages, the overvoltage of the electrode is reduced to about 50 mV under normal operating conditions by applying platinum group oxides to the insoluble electrode, as far as the anode is concerned, and further improvement/improvement is expected. You've reached a level you don't have.

On the other hand, regarding the cathode, in the case of the conventionally used mild steel, stainless steel, and nickel electrodes, an overvoltage of 300 to 400 mV was generated under normal operating conditions. Therefore, activation of these electrode surfaces and reduction of overvoltage have been studied, and many techniques have been developed so far. Examples of producing a highly active cathode while the electrode surface is an oxide by plasma spraying nickel oxide, Raney nickel-based plating, nickel and tin composite plating, activated carbon and oxide composite plating There is an example where it is applied to the electrode surface, and all of them are intended to be used as a cathode for hydrogen generation in caustic soda. However, in order to reduce the electrolysis voltage, it is necessary to further reduce the cathode overvoltage, and therefore various cathodes as described below have been proposed.

For example, in Patent Document 1, a noble metal coating made of one type of noble metal or a mixture or alloy of two types or three or more types of noble metals, and a film containing one type or two or more types of base metals such as nickel in the noble metal coating. An electrode for hydrogen generation has been proposed in which is coated on a conductive base material such as nickel. However, it is known that these hydrogen generation electrodes have a problem that they are easily poisoned by impurities such as iron in the electrolytic solution (see Patent Document 2).

Thus, conventionally, a hydrogen generation electrode having a low hydrogen overvoltage, which carries platinum, has been proposed. However, the hydrogen generating electrode supporting platinum is easily susceptible to poisoning due to a slight amount of iron ions present in the electrolytic solution, and even if the iron ion concentration is 1 ppm or less, the hydrogen overvoltage is Therefore, further improvement is being investigated for use in an industrial electrolysis or the like of an aqueous solution of an alkali metal chloride in which an iron ion is easily mixed in the electrolytic solution.

Furthermore, attempts have been widely made in the past to provide the hydrogen generation electrode itself with properties that make it difficult for iron to adhere to it, or that performance will not deteriorate even if it adheres. For example, an electrode for hydrogen generation has been proposed in which a catalyst containing platinum and ruthenium and at least one of gold and silver, or a catalyst containing particles of an organic polymer is carried on a conductive substrate (Patent Document 3). The hydrogen generating electrode has an extremely small increase in overvoltage even when iron ions are present in the catholyte, and is certainly excellent in that it can reduce the amount of energy used for electrolysis of the aqueous alkali metal chloride solution. Is an electrode for hydrogen generation. However, platinum, ruthenium, gold, and silver are all expensive materials, and when polytetrafluoroethylene is contained therein, the cost becomes even higher. Therefore, even in this case, there is still a problem to be improved from the economical point of view.

On the other hand, an electrode for hydrogen generation using a catalyst composed of platinum and cerium oxide has been proposed (Patent Document 4). The hydrogen generating electrode composed of the catalyst of platinum and cerium oxide has a low overvoltage, is suppressed from being affected by iron ions, and exhibits excellent performance as a hydrogen generating electrode for electrolysis of an aqueous solution of an alkali metal chloride. Further, a proposal has been made to provide an intermediate layer made of nickel oxide between a catalyst made of platinum and cerium oxide and a base material, and further studies are being made to further improve the cost aspect.

In such a case, a conductive metal is heretofore coated with a cerium-platinum mixture-based electrode active substance containing at least one of cerium metal, cerium oxide or cerium hydroxide and platinum metal. In the hydrogen generating electrode, the composition of the electrode active material is cerium-rich with a mole fraction of platinum of 15 to 30 mol% and a cerium mole fraction of 70 to 85 mol% in terms of metal. An electrode was developed (Patent Document 5). Furthermore, a platinum alloy of platinum and one kind of transition metal element selected from the group of nickel, cobalt, copper, silver and iron is supported on the conductive substrate, and the platinum content in the platinum alloy is in a molar ratio. A hydrogen generating electrode having a range of 0.40 to 0.99 has also been developed (Patent Document 6).

JP-A-57-23083 JP 64-8288 JP-A-63-72897 Japanese Patent Laid-Open No. 2000-239882 International Publication No. 2011/040464 Patent 4888218

As described above, various electrodes for hydrogen generation have been developed so far, but in the ion-exchange membrane salt electrolysis process, a large amount of power is consumed, and therefore, for example, the overvoltage converted from the hydrogen generation potential is lowered by only a few mV. Even if it can be done, the annual cost reduction effect of electrolysis becomes very large. Therefore, it is required to further reduce the overvoltage of the hydrogen generating electrode.

Also, in the electrolysis method, when electrolysis is stopped, a current flows in a direction to eliminate the potential difference between the anode and the cathode. This current flows in the opposite direction to that during electrolysis, and is called a reverse current. As a result of studies by the present inventors, it has been clarified that, in the conventional hydrogen generating electrode, this reverse current reduces the effective surface area of the electrode catalyst such as platinum and deteriorates the hydrogen generating electrode.

Under such circumstances, the present invention can reduce the overvoltage converted from the hydrogen generation potential of the hydrogen generation electrode, and further, the reduction of the effective surface area of the platinum catalyst due to the reverse current when the electrolysis is stopped is effective. The main object of the present invention is to provide an electrode for hydrogen generation, which is suppressed physically. Another object of the present invention is to provide a method for manufacturing the hydrogen generating electrode, and an electrolysis method using the hydrogen generating electrode.

The present inventor has diligently studied to solve the above problems. As a result, on the conductive substrate, at least having a coating film containing platinum, nickel oxide, and cerium oxide, according to the hydrogen generating electrode, the overvoltage converted from the hydrogen generation potential of the hydrogen generating electrode, It has been found that the reduction of the effective surface area of the platinum catalyst due to the reverse current when the electrolysis is stopped can be effectively suppressed. The present invention has been completed by further studies based on such findings.

That is, the present invention provides the inventions of the following modes.
Item 1. An electrode for hydrogen generation, which has a coating film containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate.
Item 2. Item ^2. The hydrogen generating electrode according to Item 1, wherein the amount of platinum supported on the coating film is 2 g/m ² or more.
Item 3. Item 3. The hydrogen generating electrode according to Item 1 or 2, wherein the conductive base material contains nickel.
Item 4. A method for producing an electrode for hydrogen generation, comprising a step of forming a coating film containing at least platinum, nickel oxide, and cerium oxide on a conductive base material.
Item 5. An electrolysis method of using a hydrogen generating electrode according to any one of Items 1 to 3 in the electrolysis method of a solution containing water.
Item 6. Use of an electrode having a coating containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate for hydrogen generation.

According to the present invention, the overvoltage converted from the hydrogen generation potential of the hydrogen generation electrode can be lowered, and further, the reduction of the effective surface area of the platinum catalyst due to the reverse current when the electrolysis is stopped is effectively suppressed. Moreover, an electrode for hydrogen generation can be provided. Further, according to the present invention, it is possible to provide a method for producing the hydrogen generating electrode and an electrolysis method using the hydrogen generating electrode.

It is a schematic diagram of the cell used for the measurement of the initial hydrogen generation potential of the example. It is a figure which shows the cycle in the reverse current tolerance test of an Example. It is a graph which shows the initial hydrogen generation potential measured in the Example. It is a graph which shows the hydrogen generation potential in the reverse current tolerance test of an Example.

The hydrogen generating electrode of the present invention includes a conductive base material and a coating film provided on the conductive base material, and the coating film contains at least platinum, nickel oxide, and cerium oxide. It is characterized by The electrode for hydrogen generation of the present invention, by having such a configuration, can reduce the overvoltage converted from the hydrogen generation potential, and further, the effectiveness of the platinum catalyst due to the reverse current when the electrolysis is stopped. The reduction in surface area is effectively suppressed. Hereinafter, the hydrogen generating electrode of the present invention, the method for producing the hydrogen generating electrode, and the electrolysis method using the hydrogen generating electrode will be described in detail.

Note that, in the present specification, the numerical value connected by “to” means a numerical value range including the numerical values before and after “to” as the lower limit value and the upper limit value. When a plurality of lower limit values and a plurality of upper limit values are described separately, any lower limit value and upper limit value can be selected and connected by "...".

1. Electrode for Hydrogen Generation The electrode for hydrogen generation of the present invention comprises a conductive base material and a coating film provided on the conductive base material. Further, the coating film contains at least platinum, nickel oxide, and cerium oxide.

The conductive base material is not particularly limited as long as it has conductivity and functions as a base material of the coating, and a conductive base material used in a known hydrogen generating electrode is used. Can be used.

The conductive base material preferably contains a metal, and more preferably is composed of a metal. The metal preferably includes nickel, stainless steel, iron, copper, titanium, steel and the like, and among these, nickel is preferable. While reducing the overvoltage converted from the hydrogen generation potential, from the viewpoint of effectively suppressing the reduction of the effective surface area of the platinum catalyst due to the reverse current at the time of stopping the electrolysis, in the hydrogen generation electrode of the present invention, a conductive group The material is preferably composed of nickel. As the conductive base material containing nickel, in addition to the one made of nickel, for example, a stainless steel surface coated with nickel is also suitable.

Also, the shape of the conductive base material is not particularly limited, and may be plate-shaped, rod-shaped, porous (expanded metal, punching metal, blind, etc.). From the viewpoint of increasing the surface area of the coating film provided on the conductive substrate, it is preferably porous.

The size of the conductive substrate is not particularly limited and may be appropriately set according to the scale of electrolysis, the size of the hydrogen generating electrode, etc., for example, the length is about 300 mm to 2,500 mm, and the width is 1. The thickness is about 200 mm to 1,500 mm, and the thickness is about 0.1 mm to 6 mm.

The surface of the conductive base material may be roughened from the viewpoint of improving the adhesion of the coating. The surface roughness Ra of the conductive base material can be set to, for example, about 1 to 10 μm. Examples of the method for roughening the surface of the conductive base material include blast treatment.

Further, the surface of the conductive base material may be subjected to etching treatment from the viewpoint of improving the adhesion of the coating film. Examples of the etching method include a method of immersing the conductive base material in an acid such as hydrochloric acid. Further, after the etching treatment, it is preferable to wash with water and dry until the surface of the conductive substrate becomes neutral.

In the hydrogen generating electrode of the present invention, the coating is formed on the conductive base material. More specifically, the coating is preferably formed on the surface of the conductive base material.

The coating contains platinum, nickel oxide, and cerium oxide. In the coating, the state of platinum is not particularly limited, but it is preferable that at least a part of platinum is contained as platinum metal, and platinum oxide, platinum hydroxide or the like may be contained. Further, at least a part of nickel is contained as nickel oxide, and nickel metal, nickel hydroxide and the like may be further contained. Also, with respect to cerium, at least a part thereof is contained as a cerium oxide, and a cerium metal, a cerium hydroxide or the like may be further contained. Further, it may be in the state of an alloy of each of the above-mentioned metals or an amorphous metal.

The molar ratio of platinum element, nickel element, and cerium element (Pt/Ni/Ce) contained in the coating film is not particularly limited, but the nickel element is preferably 0.05 to 5 moles per 1 mole of platinum. The amount is more preferably about 0.5 to 2 mol. Further, the amount of cerium element is preferably about 0.05 to 10 mol, and more preferably about 0.5 to 2 mol with respect to 1 mol of platinum. By containing platinum, nickel, and cerium contained in the coating in these ranges, while further reducing the overvoltage converted from the hydrogen generation potential, the platinum catalyst of the reverse catalyst at the time of stopping the electrolysis The reduction of the effective surface area can be suppressed more effectively.

Further, while lowering the hydrogen generation potential, from the viewpoint of effectively suppressing the decrease in the effective surface area of the platinum catalyst due to the reverse current when the electrolysis is stopped, the platinum content in the coating (that is, the platinum catalyst supported amount) is , Preferably 2 g/m ² or more, more preferably 3 g/m ² or more, still more preferably 4 g/m ² or more. The larger the amount of platinum catalyst supported, the more effective it is. However, from the economical viewpoint, the upper limit of the amount of platinum catalyst supported is, for example, 20 g/m ² .

From the same viewpoint, the thickness of the coating film is preferably 0.1 μm or more, more preferably 0.5 μm or more, and further 1 μm or more. The thicker the coating, the more effective it is. However, from the economical viewpoint, the upper limit of the thickness of the coating is, for example, 20 μm.

The method for forming a coating film on a conductive substrate is not particularly limited, but as described below, for example, a solution containing a platinum compound, a nickel compound, and a cerium compound is applied onto the conductive substrate, It can be suitably formed by a method of firing the formed coating film to thermally decompose these compounds.

The coating may contain other metals different from platinum, nickel, and cerium. Examples of other metals include lanthanum, zirconium, niobium, molybdenum, and the like. When the coating film contains other metal, the content thereof is preferably 5 mol% or less, more preferably 1 mol% or less, further preferably 0.5 mol% or less. In the hydrogen generating electrode of the present invention, the metal contained in the coating is preferably 95 mol% or more in total of platinum, nickel, and cerium, more preferably 99 mol% or more, and 99.5 mol. % Or more, 99.9 mol% or more, and further 100 mol% (that is, substantially no other metal is contained) is also preferable.

The electrode for hydrogen generation of the present invention is an electrode for a known electrolysis method of a solution containing water (for example, water, an aqueous solution of an alkali metal chloride such as sodium chloride, an aqueous solution of an alkali metal hydroxide such as sodium hydroxide). It is preferably used to generate hydrogen from the electrode. That is, the hydrogen generating electrode of the present invention is suitable as a cathode in a method of electrolyzing a solution containing water.

2. Method for Producing Hydrogen Generation Electrode The method for producing a hydrogen generation electrode of the present invention includes at least a step of forming a coating film containing platinum, nickel oxide, and cerium oxide. The method for forming the coating is not particularly limited, and includes pyrolysis method, powder sintering method, electroplating method, dispersion plating method, thermal spraying method, arc ion plating method, platinum, nickel oxide, and cerium oxide. A known method can be employed in which a coating film containing is formed on the conductive substrate.

Among the methods for forming these coatings, the thermal decomposition method is preferable. In the thermal decomposition method, for example, a step of applying a solution containing at least a platinum compound, a nickel compound, and a cerium compound on a conductive base material to form a coating film of the solution on the conductive base material, Firing the coating film on the conductive base material to form a coating film containing at least platinum, nickel oxide, and cerium oxide on the conductive base material.

The platinum compound is not particularly limited as long as it contains platinum in the coating by thermally decomposing by firing of the coating film, for example, dinitrodiammine platinum, chloroplatinic acid, tetraammine platinum nitrate, hexaammine platinum hydroxide, Examples include bis(acetylacetonato)platinum. The platinum compound may be one kind or two or more kinds.

Further, the nickel compound is not particularly limited as long as it is thermally decomposed by firing of the coating film and contains nickel oxide in the coating film, and examples thereof include nickel nitrate, nickel sulfate, nickel carbonate, nickel chloride and nickel acetate. Is mentioned. The nickel compound may be one kind or two or more kinds.

Further, the cerium compound is not particularly limited as long as it is pyrolyzed by firing the coating film and contains cerium oxide in the coating film, for example, cerium nitrate, cerium sulfate, cerium carbonate, cerium chloride, cerium acetate, etc. Is mentioned. The cerium compound may be one kind or two or more kinds.

The molar ratio (Pt/Ni/Ce) of platinum element, nickel element, and cerium element contained in the solution is not particularly limited, and it can be adjusted so as to be the molar ratio in the above-mentioned coating.

The solvent contained in the solution is not particularly limited, but those capable of dissolving the platinum compound, nickel compound and cerium compound are preferable. Specific examples of the solvent include water, inorganic acids such as nitric acid, hydrochloric acid, sulfuric acid and acetic acid, lower alcohols such as methanol, ethanol, propanol and butanol, and mixed solutions containing at least two of these. Further, from the viewpoint of suppressing dissolution of the conductive base material, a pH adjusting agent or the like may be added to the solution, and from the viewpoint of complexing platinum, nickel, and cerium to increase the surface area, lysine , Citric acid, etc. may be added.

The total concentration of platinum, nickel, and cerium in the solution is not particularly limited, but preferably 2% from the viewpoint of suitably forming the coating so that the amount of the platinum catalyst contained in the coating becomes a predetermined amount. As mentioned above, more preferably about 3 to 30%, further preferably about 4 to 20%.

In the step of forming a coating film, a solution containing at least a platinum compound, a solution containing at least a nickel compound, and a solution containing at least a cerium compound are prepared, and each solution is applied onto a conductive base material. Then, a coating film may be formed. At this time, the solution containing at least a platinum compound may further contain at least one of a nickel compound and a cerium compound, or the solution containing at least a nickel compound may further contain at least one of a platinum compound and a cerium compound. Or a solution containing at least a cerium compound may further contain at least one of a platinum compound and a nickel compound. Further, after coating each solution and before coating another solution, drying and firing described later may be performed to form a coating film having a multi-layer structure having different compositions.

The method of applying the solution onto the conductive base material is not particularly limited, and known methods such as a brush application method, a spray method and a dip coating method can be adopted. As described above, the surface of the conductive base material may be roughened or may be subjected to treatments such as etching, washing with water and drying.

After coating the solution on the conductive base material, it is preferable to dry the coating film before firing the coating film. The drying may be carried out under the condition that the solvent evaporates, for example, at a temperature of 200° C. or lower for about 5 to 60 minutes, and preferably at a temperature of 150° C. or lower.

Next, the obtained coating film is fired to form a coating film containing at least platinum, nickel oxide, and cerium oxide on the conductive base material to obtain a hydrogen generating electrode. The calcination can be performed, for example, in an oxidizing atmosphere such as air (for example, in the air).

Calcination may be carried out under the condition that the platinum compound, nickel compound and cerium compound in the coating film are thermally decomposed and the resulting coating film contains platinum, nickel oxide and cerium oxide. The firing temperature is preferably about 200 to 700°C, more preferably about 350 to 550°C. The firing time is preferably about 5 to 60 minutes, more preferably about 10 to 30 minutes.

The above-mentioned series of steps of coating, drying, and firing are repeated once or more, preferably a plurality of times to form a film on the conductive substrate. The number of times of the series of steps is not particularly limited, and it is preferable to repeat until the amount of platinum catalyst supported reaches a predetermined amount. When a series of steps are repeated, the composition of the solution to be applied may be the same or different, but usually the same.

By the above method, the hydrogen generating electrode of the present invention can be suitably manufactured.

3. Electrolysis Method The electrolysis method of the present invention is a method for electrolyzing a solution containing water (for example, water, an aqueous solution of an alkali metal chloride such as sodium chloride, an aqueous solution of an alkali metal hydroxide such as sodium hydroxide). It is a method using the hydrogen generating electrode of the invention. Specifically, in a known electrolysis method of a solution containing water, the hydrogen generating electrode of the present invention is used as the hydrogen generating electrode.

For example, when the hydrogen generating electrode of the present invention is used as a hydrogen generating electrode for ion exchange membrane salt electrolysis, the temperature of the electrolyte at the start of use is about 70 to 90° C., and the concentration of the electrolyte in the cathode chamber (sodium hydroxide). Can be about 20 to 40% by mass, and the current density can be about 0.1 to 10 kA/m ² .

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

<Preparation of Solution Forming Coating Film of Hydrogen Generation Electrode>
(Example 1)
Dinitrodiammine platinum nitric acid solution, nickel nitrate (II) hexahydrate, and cerium (III) nitrate hexahydrate so that the molar ratio is Pt/Ni/Ce=1/1/0.05. By mixing, a solution for forming a film of the hydrogen generating electrode was prepared.

(Example 2)
Dinitrodiammine platinum nitric acid solution, nickel nitrate (II) hexahydrate, and cerium nitrate (III) hexahydrate so that the molar ratio is Pt/Ni/Ce=1/1/0.1 By mixing, a solution for forming a film of the hydrogen generating electrode was prepared.

(Example 3)
Dinitrodiammine platinum nitrate solution, nickel (II) nitrate hexahydrate, and cerium (III) nitrate hexahydrate so that the molar ratio is Pt/Ni/Ce=1/1/0.5. By mixing, a solution for forming a film of the hydrogen generating electrode was prepared.

(Example 4)
Dinitrodiammine platinum nitrate solution, nickel nitrate (II) hexahydrate, and cerium nitrate (III) hexahydrate were mixed in a molar ratio of Pt/Ni/Ce=1/1/1. Thus, a solution for forming a film of the hydrogen generating electrode was prepared.

(Comparative Example 1)
As a hydrogen generating electrode for comparison, MD-C50 (manufactured by Daiso Engineering Co., Ltd.) was used. The Pt/Ce ratio in the catalyst layer is 1/0.6.

<Manufacture of electrodes for hydrogen generation>
A nickel plate (100 mm×100 mm×1 mm size) for use as a conductive substrate was prepared. Next, the surface of the nickel plate was roughened (surface roughness Ra=about 3 to 5 μm) by blasting. Next, the nickel plate was immersed in a 10% hydrochloric acid aqueous solution for 10 minutes, washed with water until the surface of the nickel plate became neutral, and dried to obtain a conductive substrate. Next, in the air, each of the solutions obtained in Examples 1 to 4 and Comparative Example 1 was applied to the surface of a conductive base material, dried, and fired (pyrolysis). This was repeated until the supported amount of ( ¹ ) reached a specified amount (8 g/m ² ) to obtain a hydrogen generating electrode in which a coating containing platinum, nickel oxide, and cerium oxide was formed on the surface of the conductive substrate. The solution is applied using a brush, the drying is at 120° C. for 10 minutes, and the baking is at 460° C. for 10 minutes.

<Measurement of hydrogen generation potential>
Using the hydrogen generation electrodes of Examples 1 to 4 and Comparative Example 1, the hydrogen generation potential was measured. Specifically, each hydrogen generation electrode was used as a working electrode, a cell as shown in the schematic view of FIG. 1 was assembled, and the hydrogen generation potential was measured by the current interrupt method under the condition of 6 kA/m ² . The results are shown in the graph of FIG. The structure of the cell is as follows. As a pretreatment, electrolysis was performed at 4 kA/m ² for 1 minute. In FIG. 3, Example 1 is represented by Ex1, Example 2 is represented by Ex2, Example 3 is represented by Ex3, Example 4 is represented by Ex4, and Comparative Example 1 is represented by Rf1.
Electrolyte solution: 32 wt% sodium hydroxide aqueous solution (capacity about 300 mL)
Liquid temperature: 80℃
Working electrode: each hydrogen generating electrode of Examples 1 to 4 and Comparative example 1 Counter electrode: Platinum plate (25 mm x 25 mm)
Reference electrode: mercury/mercury oxide electrode (Hg/HgO) (immersed in 32 wt% sodium hydroxide aqueous solution (25° C.))

<Reverse current resistance test>
A reverse current resistance test was conducted using the hydrogen generating electrodes of Examples 1 to 4. Specifically, each hydrogen generating electrode was used as a working electrode, and a cell as shown in the schematic view of FIG. 1 was assembled. Next, a negative polarization electrolysis was performed at 10 kA/m ² for 60 minutes to prepare a sample before the test (current is in a direction usually used). Then, 1 kA/m ² for 45 minutes of anodic polarization electrolysis (current is in the opposite direction to that normally used) and 9 kA/m ² for 15 minutes of negative polarization electrolysis (current is normally used). Direction) is set as one cycle, and a cycle test (see the cycle diagram of FIG. 2) in which this is repeated 20 cycles was performed, and the hydrogen generation electrode after 20 cycles was measured. The results are shown in the graph of FIG. In FIG. 4, Example 1 is represented by Ex1, Example 2 is represented by Ex2, Example 3 is represented by Ex3, and Example 4 is represented by Ex4.

<Evaluation of effective surface area of platinum catalyst>
The reduction rate of the effective surface area of the platinum catalyst after the reverse current resistance test of the hydrogen generating electrodes of Example 3 and Comparative Example 1 was measured by cyclic voltammetry (CV). The conditions of cyclic voltammetry (CV) are as follows.
Electrolyte solution: 1 mol/L H ₂ SO ₄ aqueous solution temperature: room temperature (25 to 28° C.)
Working electrode: each hydrogen generating electrode of Example 3 and Comparative example 1 Counter electrode: Platinum plate (25 mm x 25 mm)
Reference electrode: silver/silver chloride (Ag/AgCl) (immersed in saturated potassium chloride aqueous solution (room temperature))
Potential scanning range: 1.1 to −0.23 V vs. Ag/AgCl
Potential scanning speed: 100 mV/s
The results are shown in Table 1. In addition, the measurement of the reduction rate of the effective surface area of the platinum catalyst using cyclic voltammetry (CV) was conducted according to "Proposal of targets, R&D issues and evaluation methods for polymer electrolyte fuel cells (issued in January 2011, issued. (Person: Fuel Cell Practical Use Promotion Council) referred to the method described in “III-3-4 Test name: CV evaluation method” on page 22.

As shown in Table 1, when comparing the effective surface areas of the platinum catalysts before and after the reverse current resistance test, the reduction rate of Example 3 was suppressed about three times that of Comparative Example 1. This shows that the platinum catalyst functions more effectively in Comparative Example 1 after the load of reverse current is applied, and Example 3 has resistance to reverse current. Can be said. Further, as shown in FIG. 3, the absolute value of the initial hydrogen generation potential was lower than that of Comparative Example 1 (Rf1) in all Examples (Ex1 to Ex4), and a decrease in overvoltage was observed. In addition, as shown in FIG. 4, this low overvoltage continued even after the reverse current load. Therefore, the hydrogen generation electrode of the present invention can reduce the overvoltage converted from the hydrogen generation potential, and further, the reduction of the effective surface area of the platinum catalyst due to the reverse current when the electrolysis is stopped is effectively suppressed. It is shown in Table 1 and FIGS. 3 and 4 that it has resistance to reverse current.

Claims (6)

An electrode for hydrogen generation, which has a coating containing at least platinum, nickel oxide, and cerium oxide on a conductive base material. The hydrogen generating electrode according to claim 1, wherein the amount of platinum supported on the coating film is 2 g/m ² or more. The hydrogen generating electrode according to claim 1 or 2, wherein the conductive base material contains nickel. A method for manufacturing an electrode for hydrogen generation, comprising a step of forming a coating film containing at least platinum, nickel oxide, and cerium oxide on a conductive base material. An electrolysis method using an electrode for hydrogen generation according to any one of claims 1 to 3 in an electrolysis method of a solution containing water. Use of an electrode having a coating containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate for hydrogen generation.

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