TW202035795A - 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

Electrode for hydrogen generation, its manufacturing method, and hydrogen manufacturing method

Invention field The present invention relates to an electrode for hydrogen generation, its manufacturing method, and a hydrogen manufacturing method.

Background technique As far as the ion exchange membrane salt electrolysis process is concerned, the reduction of energy consumption is the biggest issue. If we analyze the cell voltage in the ion exchange membrane salt electrolysis method in detail, in addition to the theoretically necessary voltage, the voltage caused by the membrane resistance of the ion exchange membrane, the overvoltage between the anode and the cathode, the liquid resistance and the gas resistance are also added. Voltage. Among these voltages, if the overvoltage of the electrode is concerned with the anode, the platinum group oxide can be used to respond to the insoluble electrode. Under normal operating conditions, it can be reduced to about 50mV, which is beyond expectations. The level of improvement and improvement.

On the other hand, as for the cathode, in the case of conventionally used mild steel, stainless steel and nickel electrodes, an overvoltage of 300~400mV will be generated under normal operating conditions. Here, it has been explored to activate the surface of these electrodes to reduce overvoltage, and many technologies have been developed so far. There are known examples of producing a cathode with an oxide on the electrode surface and high activity at the same time by plasma spraying nickel oxide, as well as applying a lightning nickel-based plating layer, a composite plating layer of nickel and tin, and activated carbon and oxide to the electrode surface. In the example of the composite coating, any of the above is 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. Therefore, various cathodes as described below have been proposed.

For example, Patent Document 1 proposes an electrode for hydrogen generation in which a film is coated on a conductive substrate such as nickel. The film is as follows: one type of precious metal or a mixture or alloy of two or more precious metals Precious metal coating; and, a coating containing one or more base metals such as nickel in the precious metal coating. However, it is known that these electrodes for hydrogen generation have a problem that they are easily poisoned by impurities such as iron in the electrolyte (see Patent Document 2).

In this way, an electrode for hydrogen generation which is formed by supporting platinum and has a low hydrogen overvoltage has been proposed in the past. However, the hydrogen generation electrode made of platinum is very sensitive to the trace iron ions in the electrolyte and is easily affected by poisoning. Even if the iron ion concentration is less than 1ppm, the hydrogen overvoltage will still increase. The use of alkaline metal chloride aqueous solutions in which iron ions are easily mixed into the electrolyte is explored to further improve the use of industrial electrolysis.

Furthermore, there have been extensive attempts to give the hydrogen-generating electrode itself a characteristic that does not easily adhere to iron, or a characteristic that does not degrade performance even if iron adheres. For example, an electrode for hydrogen generation in which a catalyst is supported on a conductive substrate has been proposed. The catalyst includes at least one of platinum, ruthenium, and gold and silver, or further includes organic polymer particles ( Patent Document 3). Even if iron ions are present in the catholyte, the electrode for hydrogen generation has very little rise in overvoltage. It is an electrode for hydrogen generation with excellent characteristics in terms of reducing the electrolysis energy consumption of the alkali metal chloride aqueous solution. However, platinum, ruthenium, gold, and silver are all expensive materials. If polytetrafluoroethylene is included in them, they will become more expensive. Therefore, even under such circumstances, there are still issues that need to be improved from the economic perspective.

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 electrode for hydrogen generation composed of a catalyst of platinum and cerium oxide not only has a very low overvoltage and suppresses the influence of iron ions, but also shows excellent performance as an electrode for hydrogen generation for the electrolysis of aqueous alkali chloride solutions. In addition, it has been proposed to provide an intermediate layer composed of nickel oxide between the catalyst composed of platinum and cerium oxide and the substrate, and it has been discussed in order to further improve the cost surface.

Among them, an electrode for hydrogen generation has been developed so far, which is formed by coating a conductive metal with an electrode active material of a cerium-platinum mixture system. The electrode active material of the cerium-platinum mixture system contains cerium metal and oxide. At least one of cerium and cerium hydroxide and platinum metal, the electrode for hydrogen generation is characterized in that: the composition of the electrode active material is converted into metal, the molar fraction of platinum is 15-30 mol%, and the molar fraction of cerium is 15-30%. The mole fraction is 70 to 85 mole% and it is rich in cerium (Patent Document 5). In addition, an electrode for hydrogen generation was also developed, which carried platinum alloy (platinum and a transition metal element selected from the group of nickel, cobalt, copper, silver and iron) on a conductive substrate, and platinum The platinum content in the alloy is in the range of 0.40 to 0.99 in terms of molar ratio (Patent Document 6). Advanced technical literature Patent literature

[Patent Document 1] JP 57-23083 A [Patent Document 2] Japanese Patent Application Laid-Open No. 64-8288 [Patent Document 3] Japanese Patent Laid-Open No. 63-72897 [Patent Document 4] JP 2000-239882 A [Patent Document 5] International Publication No. 2011/040464 [Patent Document 6] Japanese Patent No. 4882218

Summary of the invention Problems to be solved by the invention As mentioned above, although various electrodes for hydrogen generation have been developed so far, the ion-exchange membrane salt electrolysis process consumes a lot of power. For example, even if the overvoltage converted from the hydrogen generation potential can only be reduced by a few mV , The annual cost reduction effect spent on electrolysis will become very large. Therefore, it is necessary to further reduce the overvoltage of the electrode for hydrogen generation.

In addition, as far as the electrolysis method is concerned, when the electrolysis is stopped, the current will flow in a direction to cancel the potential difference between the anode and the cathode. Since this current flows in the opposite direction to that during electrolysis, it is called reverse current. The inventors of the present case have clarified during the investigation that, in the conventional electrode for hydrogen generation, the effective surface area of the electrode catalyst such as platinum is reduced by the reverse current, and the electrode for hydrogen generation is thereby deteriorated.

Under such circumstances, the object of the present invention is to provide an electrode for hydrogen generation, which can reduce the overvoltage of the hydrogen generation electrode converted from the hydrogen generation potential, and further can effectively suppress the platinum caused by the reverse current when the electrolysis is stopped. The effective surface area of the catalyst is reduced. Furthermore, the object of the present invention is also to provide a method of manufacturing the electrode for hydrogen generation and an electrolysis method using the electrode for hydrogen generation. Means to solve the problem

In order to solve the above-mentioned problems, the inventors of the present case conducted intensive studies. As a result, it was found that the use of an electrode for hydrogen generation having a film containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate can reduce the overvoltage of the hydrogen generation electrode converted from hydrogen generation potential, and further effectively suppress electrolysis The effective surface area of the platinum catalyst decreases due to the reverse current at the stop. The present invention is based on such knowledge and insights, and has been further explored and completed.

That is, the present invention provides inventions in the following aspects. Item 1. An electrode for hydrogen generation, which has a film containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate. Item 2 is the electrode for hydrogen generation in Item 1, wherein the platinum supporting amount of the film is 2 g/m ² or more. Item 3. The electrode for hydrogen generation 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: forming a film containing at least platinum, nickel oxide, and cerium oxide on a conductive substrate. Item 5 An electrolysis method using the electrode for hydrogen generation as described in any one of items 1 to 3 in the electrolysis method of an aqueous solution. Item 6. Use of an electrode for generating hydrogen, the electrode having a coating film containing at least platinum, nickel oxide and cerium oxide on a conductive substrate. Invention effect

According to the present invention, an electrode for hydrogen generation can be provided, which can reduce the overvoltage of the hydrogen generation electrode converted from hydrogen generation potential, and further effectively suppress the reduction of the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped. Furthermore, according to the present invention, a method of manufacturing the electrode for hydrogen generation and an electrolysis method using the electrode for hydrogen generation can also be provided.

The form used to implement the invention The electrode for hydrogen generation of the present invention includes a conductive substrate and a coating film provided on the conductive substrate, and is characterized in that the coating film contains at least platinum, nickel oxide, and cerium oxide. The electrode for hydrogen generation of the present invention can reduce the overvoltage converted from hydrogen generation potential by having such a structure, and further can effectively suppress the reduction of the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped. The electrode for hydrogen generation of the present invention, the method of manufacturing the electrode for hydrogen generation, and the electrolysis method using the electrode for hydrogen generation are described in detail as follows.

In addition, in this manual, the numerical value linked with "~" means the numerical range including the numerical value before and after "~" as the lower limit and the upper limit. When most lower limit values and most upper limit values are recorded separately, any lower limit value and upper limit value can be selected and linked with "~".

1. Electrodes for hydrogen generation The electrode for hydrogen generation of the present invention includes a conductive substrate and a coating film provided on the conductive substrate. Furthermore, the coating film contains at least platinum, nickel oxide, and cerium oxide.

As for the conductive substrate, it is not particularly limited as long as it has conductivity and can function as a substrate of a film, and conventional conductive substrates used for electrodes for hydrogen generation can be used.

The conductive substrate preferably contains metal, and more preferably consists of metal. In addition, metals such as nickel, stainless steel, iron, copper, titanium, and steel are preferable, and nickel is particularly preferable among them. From the viewpoint of reducing the overvoltage converted from the hydrogen generation potential while effectively suppressing the reduction in the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped, the conductive substrate of the hydrogen generation electrode of the present invention is preferably made of nickel. In addition to nickel-containing conductive substrates, for example, nickel-coated stainless steel surfaces are also suitable.

In addition, the shape of the conductive substrate is not particularly limited, and examples include plate shape, rod shape, porous shape (expanded metal, stamped metal, curtain shape, 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. It can be set appropriately according to the scale of electrolysis and the size of the hydrogen generating electrode, but for example: length 300mm~2,500mm, width 1,200mm~1,500mm, thickness 0.1mm~ Around 6mm.

From the viewpoint of improving the adhesion of the film, the surface of the conductive substrate may also be roughened. Regarding the surface roughness Ra of the conductive substrate, it can be set to, for example, about 1 to 10 μm. The method for roughening the surface of the conductive substrate may be sandblasting.

In addition, from the viewpoint of improving the adhesion of the film, the surface of the conductive substrate may also be subjected to etching treatment. Examples of the etching treatment method include a method of immersing a conductive substrate in an acid such as hydrochloric acid. In addition, after the etching treatment, the surface of the conductive substrate should be washed with water until it is neutral and dried.

In the electrode for hydrogen generation of the present invention, the film is formed on the conductive substrate. More specifically, the film is preferably formed on the surface of the conductive substrate.

The coating contains platinum, nickel oxide, and cerium oxide. The state of platinum in the coating is not particularly limited, but at least a part of it is preferably contained in the form of platinum metal, and may also contain platinum oxide, platinum hydroxide, and the like. In addition, at least a part of nickel is contained in the form of nickel oxide, and may further contain nickel metal, nickel hydroxide, and the like. In addition, at least part of cerium is also contained in the form of cerium oxide, and may further contain cerium metal, cerium hydroxide, and the like. In addition, it may be an alloy of the above-mentioned metals or an amorphous metal state.

The molar ratio (Pt/Ni/Ce) of platinum, nickel, and cerium contained in the film is not particularly limited, but it can be mentioned for example: relative to 1 mol of platinum, nickel should be about 0.05~5 mol, It is more preferably about 0.5 to 2 moles. In addition, for example, relative to 1 mol of platinum, cerium is preferably about 0.05 to 10 mol, more preferably about 0.5 to 2 mol. By making the content ratios of platinum, nickel and cerium contained in the film meet these ranges, the overvoltage converted from the potential generated by hydrogen can be further reduced, and the reduction in the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped can be more effectively suppressed .

In addition, from the viewpoint of reducing the hydrogen generation potential while effectively suppressing the reduction in the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped, the platinum content in the film (that is, the platinum catalyst supported amount) can be as follows: preferably 2g/ m ² or more, preferably 3g/m ² or more, more preferably 4g/m ² or more. The greater the amount of platinum catalyst supported, the more effective it is, but from an economic point of view, the upper limit of the amount of platinum catalyst supported can be, for example, 20 g/m ² .

In addition, from the same point of view, the thickness of the coating film may be, for example, preferably 0.1 μm or more, more preferably 0.5 μm or more, and more preferably 1 μm or more. The thicker the film thickness, the more effective it is, but from an economic point of view, the upper limit of the film thickness can be, for example, 20 μm.

The method of forming a film on a conductive substrate is not particularly limited, but as described later, for example, a solution containing a platinum compound, a nickel compound, and a cerium compound can be coated on the conductive substrate, and then The formed coating film is properly formed by the method of pyrolyzing these compounds by firing.

The film may contain other metals different from platinum, nickel and cerium. Examples of other metals include lanthanum, zirconium, niobium, and molybdenum. When the film contains other metals, the content can be listed as follows: preferably 5 mol% or less, more preferably 1 mol% or less, and more preferably 0.5 mol% or less. In the electrode for hydrogen generation of the present invention, the total metal contained in the coating film is preferably 95 mol% or more of platinum, nickel and cerium, more preferably 99 mol% or more, and can be 99.5 mol% or more, 99.9 mol% % Or more, or even 100 mol% (that is, substantially free of other metals).

The electrode for hydrogen generation of the present invention is suitably used as an electrode for conventional electrolysis of aqueous solutions (such as water, aqueous solutions of alkali metal chlorides such as sodium chloride, and aqueous solutions of alkali metal hydroxides such as sodium hydroxide). The electrodes are produced. That is, the electrode for hydrogen generation of the present invention is suitable for use as a cathode in an electrolysis method of an aqueous solution.

2. Manufacturing method of electrode for hydrogen generation The method of manufacturing an electrode for hydrogen generation of the present invention includes a step of forming a film containing at least platinum, nickel oxide, and cerium oxide. The method for forming the film is not particularly limited, and it can be made by thermal decomposition, powder sintering, electroplating, dispersion plating, spraying, and arc ion plating. It can include platinum, nickel oxide, and cerium oxide. A conventional method of forming a film on a conductive substrate.

Among these film forming methods, thermal decomposition is particularly suitable. As for the thermal decomposition method, for example, the method includes the following steps: coating a solution containing at least a platinum compound, a nickel compound, and a cerium compound on a conductive substrate, and forming a solution coating film on the conductive substrate; And, the step of baking the coating film on the conductive substrate to form a coating film containing at least platinum, nickel oxide, and cerium oxide on the conductive substrate.

The platinum compound is not particularly limited as long as it can be thermally decomposed by baking the coating film to make the coating contain platinum. Examples include dinitrosodiammine platinum, chloroplatinic acid, tetraammineplatinum nitrate, and hexamethylene chloride. Amine platinum hydroxide salt, bis(acetone) platinum, etc. There may be one type of platinum compound, or two or more types.

In addition, the nickel compound is not particularly limited as long as it can be thermally decomposed by baking the coating film and the coating film contains nickel oxide. Examples include nickel nitrate, nickel sulfate, nickel carbonate, nickel chloride, and nickel acetate. There may be one type of nickel compound, or two or more types.

In addition, the cerium compound is not particularly limited as long as it can be thermally decomposed by firing the coating film and the coating film contains cerium oxide. Examples include cerium nitrate, cerium sulfate, cerium carbonate, cerium chloride, and cerium acetate. There may be one type of cerium compound, or two or more types.

The molar ratio (Pt/Ni/Ce) of platinum element, nickel element, and cerium element contained in the solution is not particularly limited, and can be adjusted by means of the aforementioned molar ratio in the film.

The solvent contained in the solution is not particularly limited, and is preferably one that can dissolve platinum compounds, nickel compounds, and cerium compounds. 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; or, a mixed solution containing at least two of these. In addition, from the viewpoint of inhibiting the dissolution of the conductive substrate, the solution can also be blended with a pH adjuster, etc., and from the viewpoint of complexing platinum, nickel, and cerium to increase the surface area, lysine can also be added Acid, citric acid, etc.

The total concentration of platinum, nickel and cerium in the solution is not particularly limited, but from the viewpoint of making the supported amount of the platinum catalyst contained in the film a predetermined amount to form a film properly, for example: 2% is preferred Above, it is more preferably about 3~30%, more preferably about 4~20%.

In addition, 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 may be prepared, and then each solution may be coated on the conductive substrate to form a coating film. In addition, at this time, the solution containing at least the 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. The solution containing at least the cerium compound further contains at least one of a platinum compound and a nickel compound. In addition, after coating each solution, it is also possible to perform drying or even baking described later before coating other solutions to form a multilayer structure film with mutually different compositions.

The method of coating the solution on the conductive substrate is not particularly limited, and conventional methods such as brush coating method, spray method, and dip coating method can be used. In addition, as described above, the surface of the conductive substrate may be roughened, and treatments such as etching, water washing, and drying may also be performed.

After coating the solution on the conductive substrate, it is preferable to dry the coating film before firing the coating film. Drying only needs to be carried out under the condition that the solvent will evaporate, for example, it can be carried out at a temperature below 200°C for about 5 to 60 minutes, and more preferably at a temperature below 150°C.

Next, the obtained coating film is fired, and a coating film containing at least platinum, nickel oxide, and cerium oxide is formed on the conductive substrate to obtain an electrode for hydrogen generation. For example, roasting can be performed in an oxidizing gas environment such as air (for example, in the atmosphere).

The firing may be performed under conditions that thermally decompose the platinum compound, nickel compound, and cerium compound in the coating film so that the resulting coating film contains platinum, nickel oxide, and cerium oxide. The firing temperature is preferably about 200~700℃, more preferably about 350~550℃. In addition, the roasting time is preferably about 5 to 60 minutes, more preferably about 10 to 30 minutes.

A series of steps of the above-mentioned coating, drying, and firing are performed more than once, preferably repeatedly, to form a film on the conductive substrate. The number of the series of steps is not particularly limited, and it is preferable to repeat the steps until the supported amount of the platinum catalyst becomes a predetermined amount. In addition, when a series of steps are repeated, the composition of the coating solution may be the same or different, and it is generally set to be the same.

The electrode for hydrogen generation of the present invention can be suitably manufactured by the above method.

3. Electrolysis method The electrolysis method of the present invention is a method in which the electrode for hydrogen generation of the present invention is used in the electrolysis method of an aqueous solution (for example, an aqueous solution of alkali metal chloride such as water or sodium chloride, an aqueous alkali metal hydroxide solution such as sodium hydroxide) . Specifically, the electrode for hydrogen generation of the present invention is used as the electrode for hydrogen generation in the conventional electrolysis method of aqueous solution.

For example, when the electrode for hydrogen generation of the present invention is supplied to the electrode for hydrogen generation of ion-exchange membrane method salt electrolysis, the electrolyte temperature at the beginning of use can be about 70~90℃, and the electrolyte concentration of the cathode chamber ( Sodium hydroxide) is about 20-40% by mass, and the current density is about 0.1-10 kA/m ² . Example

The present invention is explained in more detail in the following examples, but the present invention is not limited by them.

>Prepare the solution used to form the film of the electrode for hydrogen generation> (Example 1) Mix the nitric acid solution of dinitrosodiammine platinum, nickel(II) nitrate hexahydrate and cerium(III) nitrate hexahydrate in the manner of Pt/Ni/Ce=1/1/0.05 molar ratio to prepare A solution used to form the film of the electrode for hydrogen generation.

(Example 2) Mix the nitric acid solution of dinitrosodiamine platinum, nickel(II) nitrate hexahydrate and cerium(III) nitrate hexahydrate in the manner of Pt/Ni/Ce=1/1/0.1 molar ratio to prepare A solution used to form the film of the electrode for hydrogen generation.

(Example 3) Mix the nitric acid solution of dinitrosodiammine platinum, nickel(II) nitrate hexahydrate and cerium(III) nitrate hexahydrate in the manner of Pt/Ni/Ce=1/1/0.5 molar ratio to prepare A solution used to form the film of the electrode for hydrogen generation.

(Example 4) Mix dinitrosodiaminoplatinum nitric acid solution, nickel(II) nitrate hexahydrate and cerium(III) nitrate hexahydrate in the manner of Pt/Ni/Ce=1/1/1 molar ratio to prepare A solution used to form the film of the electrode for hydrogen generation.

(Comparative example 1) MD-C50 (manufactured by DAISO ENGINEERING CO., LTD.) was used as a comparative electrode for hydrogen generation. In addition, the Pt/Ce ratio of the catalyst layer is 1/0.6.

>Manufacture of electrodes for hydrogen generation> Prepare nickel plates (100mm×100mm×1mm size) for use as conductive substrates. Next, the surface of the nickel plate is roughened by sandblasting (surface roughness Ra=about 3 to 5 μm). 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 prepare a conductive substrate. Then, each solution obtained in Examples 1 to 4 and Comparative Example 1 was repeatedly applied to the surface of the conductive substrate, dried, and calcined (thermal decomposition) in the atmosphere until the supported platinum catalyst reached a predetermined amount. (8g/m ² ), and an electrode for hydrogen generation in which a film containing platinum, nickel oxide and cerium oxide has been formed on the surface of a conductive substrate. In addition, the coating of the solution is coating using a brush, drying at 120°C for 10 minutes, and baking at 460°C for 10 minutes.

>Measurement of hydrogen generation potential> The hydrogen generation electrodes of Examples 1 to 4 and Comparative Example 1 were used to measure the hydrogen generation potential. Specifically, each electrode for hydrogen generation is set as a working electrode, the electrolytic cell shown in the schematic diagram of Fig. 1 is assembled, and the hydrogen generation potential is measured by the current interruption test method under the condition of 6 kA/m ² . The results are shown in the graph in Figure 3. The structure of the electrolytic cell is as follows. In addition, electrolysis was performed at 4 kA/m ² for 1 minute as a pretreatment. In addition, in FIG. 3, Example 1 is shown as Ex1, Example 2 is shown as Ex2, Example 3 is shown as Ex3, Example 4 is shown as Ex4, and Comparative Example 1 is shown as Rf1. Electrolyte: 32wt% sodium hydroxide aqueous solution (capacity about 300mL) Liquid temperature: 80℃ Acting electrode: each of the electrodes for hydrogen generation in Examples 1 to 4 and Comparative Example 1. Counter electrode: Platinum plate (25mm×25mm) Reference electrode: Mercury/mercury oxide electrode (Hg/HgO) (dipped in 32wt% sodium hydroxide aqueous solution (25℃))

>Reverse current resistance test> The electrodes for hydrogen generation of Examples 1 to 4 were used to perform a reverse current resistance test. Specifically, each electrode for hydrogen generation is set as a working electrode, and an electrolytic cell as shown in the schematic diagram of FIG. 1 is assembled. Then conduct cathodic polarization electrolysis at 10kA/m ² for 60 minutes to adjust the sample before the test (the current is in the direction of general use). Then, make 1 cycle of anodic polarization electrolysis at 1kA/m ² for 45 minutes (the current is in the opposite direction to the direction of general use) and 15 minutes at 9kA/m ² (current is the direction of general use). , Make it carry out the cycle test of repeated 20 cycles (refer to the cycle diagram of Fig. 2), and measure the hydrogen generating electrode after 20 cycles. The results are shown in the graph in Figure 4. In addition, in FIG. 4, Example 1 is shown as Ex1, Example 2 is shown as Ex2, Example 3 is shown as Ex3, and Example 4 is shown as Ex4.

>Evaluation of the effective surface area of the platinum catalyst> Cyclic voltammetry (CV) was used to measure the reduction rate of the effective surface area of the platinum catalyst after the reverse current resistance test of the electrodes for hydrogen generation in Example 3 and Comparative Example 1. The conditions of cyclic voltammetry (CV) are as follows. Electrolyte: 1mol/LH ₂ SO ₄ aqueous solution Temperature: room temperature (25~28℃) Acting electrode: each electrode for hydrogen generation of Example 3 and Comparative Example 1 Counter electrode: Platinum plate (25mm×25mm) Reference electrode: Silver /Silver chloride (Ag/AgCl) (immersed in saturated potassium chloride aqueous solution (room temperature)) Potential scanning range: 1.1~-0.23V vs. Ag/AgCl Potential scanning speed: 100mV/s The results are shown in Table 1. In addition, the measurement of the effective surface area reduction rate of platinum catalysts using cyclic voltammetry (CV) is based on the "Objectives, Research and Development Issues and Evaluation Methods Proposals for Solid Polymer Fuel Cells (Issued in January 2011, issuer) : Fuel Cell Practical Promotion Council) The method contained in "III-3-4 Test Name: CV Evaluation Method" is described on page 22.

[Table 1] Effective surface area of platinum catalyst (mC/cm ² ) Effective surface area reduction rate of platinum catalyst Before reverse current resistance test After reverse current resistance test Example 3 4501.3 3883.1 13.7% Comparative example 1 3866.2 2613.0 32.4%

As shown in Table 1, if the effective surface area of the platinum catalyst is compared before and after the reverse current resistance test, Example 3 suppresses the reduction rate by about 3 times compared with Comparative Example 1. This shows that even after being subjected to a reverse current load, the platinum catalyst in Example 3 performs more effectively than Comparative Example 1, and Example 3 can be said to be resistant to reverse current. In addition, as shown in FIG. 3, the absolute value of the initial hydrogen generation potential of all the examples (Ex1~Ex4) was lower than that of the comparative example 1 (Rf1), and a decrease in overvoltage was observed. In addition, as shown in Figure 4, this lower overvoltage continues even after being subjected to a reverse current load. Therefore, the hydrogen generation electrode of the present invention can reduce the overvoltage converted from the hydrogen generation potential, and can effectively suppress the reduction in the effective surface area of the platinum catalyst caused by the reverse current when the electrolysis is stopped, and is resistant to the reverse current. It has been shown in Table 1 and Figures 3 and 4.

Figure 1 is a schematic diagram of an electrolytic cell used to determine the initial hydrogen generation potential of the embodiment. Fig. 2 is a diagram showing the cycle of the reverse current resistance test of the embodiment. Figure 3 is a graph showing the initial hydrogen generation potential measured in the embodiment. Fig. 4 is a graph showing the hydrogen generation potential of the reverse current resistance test of the embodiment.

(no)

Claims (6)

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

Images