JPH03166393A - Electrode for generating hydrogen - Google Patents

Abstract

PURPOSE:To obtain the inexpensive electrode for hydrogen generation of a low overvoltage and long life by solutionizing a specific ratio of Ti into the oxide of Ni or Co clad on a conductive base material and regulating the formation of a hydroxide in a specific aq. alkaline soln. CONSTITUTION:The oxide of at least one kind of metals of the Ni and Co is clad on the conductive base material to obtain the electrode for hydrogen generation. The Ti is incorporated as a solid soln. into the above-mentioned clad at 0.1 to 3.0mol% of the total metal. The resistance to reduction is imparted to the electrode active material of the oxide in this way. Further, the formation ratio of the hydroxide of the Ni or Co defined by the formation ratio of the hydroxide =H1 (H0+H1)X100% (H0: the height of the main intensity of X-ray diffraction of the metal, H1: the height of the main intensity of X-ray diffraction of the metal hydroxide) is so regulated as to attain <=15% when the magnetic clad is subjected to potential scanning at 0.2mV/sec from the hydrogen generation potential to 0mVvsNHE in the aq. alkaline soln. of 35% and 95 deg.C. The electrode of the low overvoltage and long life having the secure clad highly resistant to corrosive eluation is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrode for hydrogen generation in alkaline solutions such as salt electrolysis and water electrolysis.

More specifically, the present invention relates to an electrode for hydrogen generation that has low overvoltage, long life, and is inexpensive.

[Conventional technology] Eng. In the field of industrial electrolysis, as energy costs soar, in order to reduce the overvoltage used in hydrogen electrode reactions,
Research and development of active cathodes is being actively conducted.

These electrodes include those that use metals, alloys, or mixtures thereof as active materials, and those that use metal oxides, composite oxides, or mixtures of metal oxides as active materials.

The former electrodes that use metals, alloys, or mixtures thereof as active materials have the essential drawback that the overvoltage of the electrode increases over time during the continuous hydrogen electrode reaction process, and the electrode activity is lost. have.

On the other hand, one of the latter uses a metal oxide as an active material, as disclosed in Japanese Patent Application Laid-open No. 181078/1983.
In an electrode made of hot-pressed nickel powder whose surface is covered with NiO with a thickness of 0.0025 to 0.1 am,
An electrode is disclosed in which the surface layer is made of a mixed oxide of nickel and titanium in order to prevent the progress of oxidation. Since this electrode contains titanium as a mixed oxide with nickel, the overvoltage reduction is extremely insufficient, and the adhesion between the coating and the base material may deteriorate during electrolysis. . Additionally, metal oxides are easily reduced to metals within a short period of time during continuous hydrogen electrode reactions. Reduced electrodes have the same disadvantages as conventional electrodes that use metals as active materials, that overvoltage increases over time, and that the coating easily dissolves due to reverse current and loses electrode activity. be.

Further, JP-A-57-82483 discloses an electrode for hydrogen generation coated with a layer containing an oxide of at least one metal selected from nickel and cobalt, and a method for manufacturing the same. Although electrodes using metal oxides as active materials can maintain their activity for a longer period of time compared to conventionally used electrodes using metals as active materials, they are still insufficient as industrially useful electrodes. It has the disadvantage that it retains its activity for a short period of time. The reason for this was that the metal oxide was gradually reduced to metal due to continuous hydrogen electrode reactions, and the overvoltage increased over time. As an electrode to improve this, an electrode for hydrogen generation (Japanese Patent Laid-Open No. 60-28682) has been proposed.

This contains titanium in order to prevent metal oxides from being reduced to metals, resulting in the overvoltage of the electrode increasing over time in the process of continuous hydrogen electrode reactions and loss of activity. , it was indeed able to maintain its activity for a long period of time. However, in some cases, the mechanical strength of the coating deteriorates over time during long-term electrolysis, and the coating does not necessarily maintain its activity for a sufficient period of time.

The reason for this is that the reverse current that inevitably occurs when an operating electrolytic cell is stopped causes the nickel in the coating to transform into hydroxide, reducing activity and causing corrosion and elution, which causes the coating to deteriorate. This resulted in a decrease in mechanical strength. Furthermore, the magnitude of the decrease in mechanical strength was proportional to the alkaline concentration of the electrolyte.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of the prior art, and prevents the mechanical strength of the coating from decreasing due to the reverse current generated when electrolysis is stopped, especially during high-temperature and high-concentration alkali treatment. I won't wake you up. The present invention aims to provide an electrode that has sufficient activity maintenance space and durability for industrial use.

[Means for Solving the Problems] As a result of intensive studies in order to prevent the mechanical strength of the coating from decreasing, the present inventors have made an oxide of at least one metal selected from nickel and cobalt conductive. The hydrogen generating electrode coated on the base material contains 0.1 to 3.0 mol% of titanium as a solid solution based on the total metal elements in the coating, and 35% titanium in an alkaline aqueous solution at 90°C. The coating is turned on from the hydrogen generation potential (vs. NIIE
), when the potential is scanned at 0.2IIIV/sec,
By setting the production ratio of nickel and/or cobalt hydroxide in the coating to 15% or less, which is calculated from the ratio of the peak heights of line diffraction, the mechanical properties of the coating are improved, especially in high-temperature and high-concentration alkaline solutions. The present invention was completed based on the discovery that the optical strength was greatly improved.

The oxide of at least one metal selected from nickel and cobalt in the coating provides the electrode with activation, that is, low overvoltage (
(i.e., acts as an electrode active material), and titanium provides reduction resistance to the electrode active material.

The reduction resistance referred to herein is defined as the property of the electrode active material maintaining its oxide state without being reduced even after continuous hydrogen generation reactions.

Furthermore, the hydroxide production ratio referred to herein is defined as follows.

Ha: height of main strength of metal measured by X-ray diffraction method. If the coating contains two or more metals, the sum of the respective principal strengths.

H+: height of main intensity of metal hydroxide measured by X-ray diffraction method. If the coating contains hydroxides of two or more metals, the sum of the principal strengths of each metal hydroxide.

The inventors of the present application have discovered that when an electrode containing a metal oxide of nickel or cobalt as an active material is subjected to electrolysis for a long period of time in a high-temperature, high-concentration alkaline solution, the mechanical strength of the coating decreases. Examining the electrode, we found that due to the history of multiple reverse currents, the nickel in the coating transformed into hydroxide, resulting in a decrease in activity and corrosion elution, causing a decrease in the mechanical strength of the coating. I discovered that.

Then, the hydroxide production ratio defined in the above formula is set to 1
To complete a long-life hydrogen generation electrode that does not cause any decrease in the mechanical strength of the coating, even if it is subjected to electrolysis for a long period of time, especially in a high-temperature, high-concentration alkaline solution, by setting the content to 5% or less. was completed.

In addition, in view of this, it is preferable that the oxidation degree of the coating, preferably the initial oxidation degree, is 20 to 75%, so that the hydroxide production ratio is 15% or less and the hydrogen overvoltage is low and the coating has a long life. can be easily obtained.

The initial oxidation degree referred to herein is the oxidation degree in a non-energized state, and the oxidation degree is defined as follows.

Oxidation degree - H2 x 100 (X) Ha + H2 HssHeight of main strength of metal measured by X-ray diffraction method. If the coating contains two or more metals, the sum of the respective principal strengths.

H2: Height of main intensity of metal oxide measured by X-ray diffraction method. If the coating contains oxides of two or more metals, the sum of the principal strengths of the respective metal oxides.

If the degree of oxidation is less than 20%, the activity may not be maintained for a sufficient period as the object of the present invention.

Further, the specific surface area of the coating obtained by the N2 adsorption BET method is 1a+27g or less within this initial oxidation degree range.

In the present invention, the content of titanium in the coating is 0.1 to 3
,0 mol%. In order to suppress the reduction of metal oxides, the content must be 0.1 mol% or more, preferably 0.2 mol% or more, and particularly preferably 0.5 mol% or more. Moreover, if the content of titanium exceeds 3.0 mol %, the mechanical strength of the coating will decrease, and the adhesion between the coating and the base material will also decrease, which is not preferable.

The titanium content here refers to the proportion of titanium atoms among all the nickel, cobalt, and titanium atoms contained in the coating. After the coating is melted with a melting mixture and dissolved in hot water, it is dissolved in sulfuric acid. was added to make a stable acidic solution, and then all the elements were individually quantified by atomic absorption spectroscopy or plasma emission spectroscopy, and titanium atoms are expressed as mol%.

In the present invention, the oxide of at least one metal selected from nickel and cobalt may be a single nickel oxide, a single cobalt oxide, or a nickel oxide and a single cobalt oxide. It may be a mixture with cobalt oxide or a composite oxide of nickel and cobalt.

Among these, the most preferred is nickel oxide. Cobalt oxide is suitable for the purposes of the present invention, as is nickel oxide, but when compared in detail, nickel oxide is superior to cobalt oxide in terms of electrode activity.

In the present invention, titanium may be a titanium metal or a titanium metal oxide, and is dissolved in at least one metal oxide selected from nickel and cobalt. When nickel and/or cobalt and titanium form a composite oxide in the coating, the hydrogen overvoltage increases and the mechanical strength of the coating decreases. By containing titanium as a solid solution, the present invention forms a coating with low hydrogen overvoltage and excellent mechanical strength.

Generally, methods for confirming that a substance having a certain crystal structure is a solid solution include a method of measuring the lattice constant of the crystal structure, a method of examining the X-ray diffraction pattern of the substance, and the like. The solid solution referred to in the electrode coating of the present application is
Refers to a coating in which no peaks of titanium alone, titanium oxide, or composite oxides of nickel and/or cobalt and titanium are detected in a coating measured using an X-ray diffraction method.

Next, as a method for obtaining the electrode coating of the present invention, nickel,
A raw material powder consisting of a mixture of an oxide of at least one metal selected from cobalt, or a metal or metal compound capable of forming an oxide, and a metal or metal compound capable of forming an oxide or oxide of titanium. , a method of thermal spraying by plasma spraying or flame spraying, and a method of subsequently baking in a reducing atmosphere are preferred.

When using the above thermal spraying method, raw material powders containing nickel, cobalt, and titanium include, for example, oxides, hydroxides,
Although metals, carbonates, formates, oxalates, etc. can be used, particularly preferred raw material powders are oxides.

All of these methods are methods that can be applied to the electrode of the present invention, but they are capable of reliably obtaining a coating having a predetermined composition and coating oxidation degree, have excellent electrode activity, and have a long life. The most preferable method in terms of obtaining the desired amount is thermal spraying.

In other words, in electrodes made by thermal spraying, the process of spraying, solidifying, and forming a coating from the raw powder material is completed in an instant, so non-stoichiometric compositions can easily form, resulting in highly active electrode coatings. is obtained. Furthermore, by relatively simple and reliable methods such as mixing and granulation, it is possible to reliably obtain a uniform composition consisting of a plurality of particles, and by thermal spraying this, it is possible to freely obtain the desired electrode coating. can.

Therefore, the thermal spraying method is the most suitable method for the purpose of the present invention, which is to obtain a highly active and long-life electrode made of a plurality of compositions. When using the thermal spray method, it is important to improve the affinity between the electrode active material and the substance that provides reduction resistance, and to fully demonstrate each function, in order to obtain a highly active and long-life electrode. It is. For this purpose, it is preferable to thoroughly mix raw material powder consisting of a substance that imparts electrode activity and a substance that imparts resistance to reduction, pulverize it, granulate it, and then thermally spray it.

As a method of granulation molding, for example, JP-A-59-1002
The method disclosed in No. 79 is applied.

As a method for spraying the granulated molded product, a flame spraying method and a plasma spraying method can be applied. A more preferred method is plasma spraying. Plasma spraying uses argon, nitrogen,
By passing a plasma gas selected from hydrogen, helium, etc. through a gap in a DC arc, the gas is dissociated and ionized, resulting in a plasma that has a high temperature ranging from several thousand degrees to more than 10,000 degrees, a constant heat capacity, and a high velocity. This is a method to extract it as a frame.

The granulated raw material powder is transported by an inert gas and poured into this plasma flame. The granulated molded product taken into the frame melts and flies, collides with the target electrode base material surface, and is cooled and solidified to form a coating. This process of melting, flying, and collision ends instantly, and the time is estimated to be 0.1 to loo+sec. The temperature, heat capacity, and speed of the plasma flame are basically determined by the selection of plasma gas and arc power.

The plasma gas is preferably used as a mixed gas, and particularly preferably hydrogen is one of the constituents of the plasma gas, so that the coating of the present invention can be easily obtained. Also,
The coating of the present invention is easily obtained by coating by thermal spraying and then baking in a reducing atmosphere.

The thickness of the coating may be from 10 to 300 microns. If the thickness of the coating is less than 10 .mu.m, the overvoltage cannot be reduced sufficiently, and if it exceeds 300 .mu.m, the overvoltage cannot be reduced below a certain value, which is not economical.

A necessary property of the conductive substrate is that it has sufficient corrosion resistance at the operating potential and at the stopping potential in the electrolyte to which the hydrogen generating electrode is exposed. In an electrode base material having an active and porous coating as in the present invention, even during the period when hydrogen is generated on the surface layer of the electrode coating, the surface layer of the base material is exposed to a higher potential than the surface layer of the coating. It is not uncommon for the potential to be higher than the equilibrium potential for iron elution and deposition.

Examples of general-purpose materials suitable as the base material for the electrode of the present invention include nickel, nickel alloys, austenitic stainless steel, and ferritic stainless steel. Among them, nickel, nickel alloy, and austenitic stainless steel are suitable as the base material for the electrode of the present invention, and particularly preferred are nickel and nickel alloy.

Further, conductive electrode base materials having a dense coating of nickel, nickel alloy, or austenitic stainless steel on the surface layer are naturally suitable base materials for the electrode of the present invention. Such a dense and corrosion-resistant coating can be achieved by many known methods, such as electroplating, chemical plating, hot-dip plating, rolling or explosive crimping, and metal composite bonding (cladding).
It can be obtained by methods such as , vapor deposition, and ionization plating.

The shape of the electrode base material allows the generated hydrogen gas to escape quickly.
It is preferable to have a structure that does not cause extra voltage loss due to current shielding by hydrogen gas, has a large effective electrolytic surface area, and is unlikely to cause current concentration. A base material having such a shape can be obtained from a wire mesh having an appropriate wire diameter and wire spacing, a perforated plate having an appropriate thickness, hole diameter, and pitch, or an expanded metal.

The electrode of the present invention can be used as an electrode for hydrogen generation in common salt electrolysis using the ion exchange membrane method and diaphragm method, electrolysis of alkali metal halides other than common salt, water electrolysis, mirabilite electrolysis, and the like. The electrolytic solution in contact with the electrode according to the present invention is preferably alkaline. Further, the type of electrolytic cell can be applied regardless of whether it is a monopolar type or a bipolar type, and it can also be used as a bipolar type in water electrolysis.

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited only to these Examples.

In addition, each component described in the examples! (Parts) are parts by weight.

Example 1 A mixture consisting of 100 parts of nickel oxide (N i O) powder, 2.2 parts of titanium oxide (Ti02) powder, 2.25 parts of binder (gum arabic), 0.7 parts of dispersant (carboxymethyl cellulose), and 0.7 parts of surfactant ( sodium lauryl sulfate) o. oot part preservative (phenol) 0.1 part water 1
00 parts of an aqueous solution and stirred vigorously to prepare a homogeneous suspension.

When the particle size of nickel oxide and titanium oxide was measured using electron micrographs, the particle size of nickel oxide was 0.2~
The particle size of titanium oxide is in the range of 2 μm to 10 μm.
It was within the usual range.

When this suspension was granulated using a spray drying type granulator, the particle size range was 5 to 50 μm and the crushing strength was 5 g/particle.
A spherical granulated molded product with a water content of 0.1% by weight or less was obtained.

Next, this granulated molded product was plasma melted onto an electrode substrate.

The base material is a 5x5cm nickel wire mesh (wire diameter 0.710
ll+% #14 mesh) was degreased with trichlene,
It was used after being blasted with alumina. A mixed gas of nitrogen and hydrogen was used as the plasma gas, and its flow rate was 3/I1 of 2NII13/H of nitrogen and 0.4N of hydrogen.

The distance between the electrode base material and the tip of the thermal spray gun is lOcm,
The angle between the plasma flame and the surface of the electrode base material was 90''. The thickness of the coating was 150 μm on the front surface of the electrode base material and 100 μm on the back surface.

Using another sample prepared in exactly the same manner as above, the composition and degree of oxidation of the electrode coating were investigated as follows.

Add sodium peroxide and sodium carbonate to the coating,
After firing at 0° C., the coating was dissolved in sulfuric acid and the titanium content in the coating was determined by plasma emission spectroscopy, and the titanium content was 2.0 mol %.

Furthermore, by examining the lattice constant and X-ray diffraction pattern of the crystal structure of this coating, it was confirmed that the crystal structure of the electrode coating of the present invention was a solid solution. X-ray diffraction measurements were performed using a diffractometer Rotaflex RU-2 manufactured by Rigaku Denki.
This was done using 00.

Figures 1a and b are the X-ray diffraction patterns of the coating. The coating is made of NiO and Ni, and the initial oxidation degree is 72%.
It turned out to be. Even when the X-ray diffraction peak intensity was expanded (FIG. 1b), no peaks attributed to titanium oxide, titanium metal, or nickel-titanium composite oxide were detected.

Furthermore, to confirm that it was a solid solution, the nickel oxide and titanium oxide used in Example 1 were mixed in the same ratio as in Example 1, and thoroughly ground in an agate mortar. After that, when the chemical structure of this mixed powder was investigated by X-ray diffraction, a peak of titanium oxide alone was clearly detected (Figure 2 a and b).
.

This shows that the coating produced in Example 1 is a solid solution.

Next, considering the coating to be cubic based on the peak of NiO, the lattice constant was determined from the peak position, and was found to be 4.183. The Ni electrode was manufactured under the same conditions as this example using only powdered nickel oxide without adding titanium oxide.
The lattice constant of O is 4. 1785, and there is a slight difference.

From the above, it can be seen that in the present coating, titanium exists in a solid solution state in the di-sokenole oxide.

Next, this electrode was placed in a cell containing a 45% aqueous solution of caustic soda, with a platinum wire as a counter electrode, so that the front surface of the electrode faced the platinum wire. Current density 100A/d+2100℃
Once a day, reverse current 0.3A/da2 is applied under the electrolytic conditions of
Electrolysis was performed continuously by forcing the addition of time.

Electrolysis was carried out for 800 hours, and changes in hydrogen overvoltage, degree of oxidation of the coating, and rate of weight loss of the coating were determined. The result is the first
Shown in the table.

Table 1: The increase in hydrogen overvoltage was slight, and no decrease in the mechanical strength of the coating was observed.

In addition, the electrode after electrolysis was placed in a 35% alkaline aqueous solution at 90°C, and OIII (vs
．． When the potential was scanned at 0.2 Ilv/sec up to NHE), the nickel hydroxide production ratio of the coating calculated from the ratio of the peak heights of X-ray diffraction was 10%.

The weight loss rate of the coating is calculated by combining the weight loss due to the reduction of the metal oxide to the metal and the weight loss caused by peeling off from the base material due to a decrease in the mechanical strength of the coating. Indicates the numerical value that will be applied.

Examples 2 to 6 Samples were prepared in exactly the same manner as in Example 1 using the same raw materials of nickel oxide and titanium oxide as in Example 1 and varying the amounts added. The titanium content of each electrode is
It is summarized in the table. The degree of oxidation of these electrodes measured by X-ray diffraction was 66-71%.

Comparative Examples 1 to 4 Using the same raw materials of nickel oxide, titanium oxide, and chromium oxide as in Example 1, the amounts used of each were changed, and the plasma gas of Example 1, a mixed gas of nitrogen and hydrogen, was replaced with argon. and nitrogen, and the flow rate of argon was changed to INn.
A sample was prepared under the same conditions except that the sample was +3/II and the nitrogen flow rate was 0.8 Nm'/H. In addition, when the particle size of chromium oxide was measured using an electron microscope photograph, it was found to be 0.5~
It was in the range of 3 μm. The contents of titanium and chromium in each electrode are summarized in Table 2 as well as in Example 1.

The initial oxidation degree of these electrodes measured by X-ray diffraction is 85~
It was 90%.

Examples 7 and 8 Using the same raw materials of nickel oxide and titanium oxide as in Example 1, the amounts added were changed, and the plasma gas was a mixed gas of argon and nitrogen, the flow rate of argon, INm3/H, and the flow rate of nitrogen was 0. A sample was prepared in the same manner as in Example 1 except that the temperature was set to .8 Nm3/H, and then the sample was fired at 300° C. for 4 hours in a hydrogen gas atmosphere. The degree of oxidation of these electrodes was GO%.

Example 9 A sample was prepared in the same manner as in Example 7, and then the sample was fired at 300° C. for 5 hours in a hydrogen gas atmosphere. The degree of oxidation of this electrode was 40%.

Examples 10 to 12 The raw material nickel oxide was replaced with cobalt oxide (CoO
) was used as a raw material, the same titanium oxide as in Example 1 was added in different amounts, a suspension was prepared in the same manner as in Example 1, granulation molded, and plasma sprayed to prepare samples. When the particle size of cobalt oxide was measured using an electron micrograph, it was in the range of 0.4 to 2 μm. The titanium content of each electrode is summarized in Table 2. The degree of oxidation of these electrodes measured by X-ray diffraction was 65-70%.

Comparative Example 5 The sample of Comparative Example 3 was fired at 300° C. for 4 hours in a hydrogen gas atmosphere to adjust the coating oxidation degree to 80%.

Comparative Example 6 The sample of Comparative Example 2 was fired at 350° C. for 5 hours in a hydrogen gas atmosphere to adjust the coating oxidation degree to 10%.

Comparative Examples 7 to 9 Using the same raw materials of nickel oxide and titanium oxide as in Example 1, and varying the amount of each used, Comparative Examples 7 and 8 were under the same conditions as Example 1, and Comparative Example 9 was the same as Comparative Examples 1 to 9. A sample was prepared under the same conditions as in Example 4.

The above Examples 2 to 12 and Comparative Examples 1 to 9 were electrolyzed in the same manner and under the same conditions as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Table 2 Note that the weight loss rate of the coating is calculated by combining the weight loss caused by the reduction of metal oxide to metal and the weight loss caused by peeling off from the base material due to a decrease in the mechanical strength of the coating. Indicates the numerical value.

In the coatings shown in Examples 1 to 12, the weight loss of the coatings is slight even after electrolysis, and the increase in hydrogen overvoltage is moderate, whereas in the coatings shown in Comparative Examples 1 to 9, the weight of the coatings is small even after electrolysis. The weight reduction rate is extremely large, and the hydrogen overvoltage rise is also large.

Example 13 and Comparative Example 10 Next, using samples prepared in exactly the same manner as in Example 2 and Comparative Example 2, a current density of 40 A /
Electrolysis was carried out at dII12 and 90°C for 11 months. Table 3 shows the hydrogen overvoltage, degree of oxidation of the coating, specific surface area, and crushing strength of the coating before and after electrolysis.

Here, the crushing strength of the coating is the area of the tip of 0.2 nua.
Using a precision screwdriver (2) as an indenter, place it oppositely so that the indenter surface of the tip of the driver is in complete contact with the coating of the object to be measured, and apply a load perpendicular to the coating surface to cover the load when the coating surface breaks. It is defined as the crushing strength of

The degree of oxidation of the coating and the hydrogen overvoltage are those of Examples 1 to 12 and Comparative Example 1.
Measurements were carried out in exactly the same manner as in ~.

Further, the specific surface area was measured by the N2 adsorption BET method.

As shown in Table 3, in the present invention, the specific surface area of the coating when no current is applied is less than III+2/g, and the crushing strength of the coating is 90 to 100 kg/a+a+2. On the other hand, in Comparative Example 10, initially when the degree of oxidation was 85%, both the specific surface area and the crushing strength of the coating were almost the same as in Example 10, but when the degree of oxidation decreased to 65% after electrolysis. The crushing strength of the coating with a specific surface area of 2.4 m'/gs was 30 kg/am2, and it can be seen that the structure of the coating is clearly different.

[Effects of the Invention] As detailed above, according to the present invention, electrolysis stop I? ．． Due to the reverse current that sometimes occurs, it prevents the reduction in the activity of the coating and the corrosion and elution of the coating that tends to occur at higher temperatures and higher concentrations, and prevents the corrosion of the coating even in higher temperature and higher concentration alkaline solutions. An electrode can be obtained that has a firm coating that does not cause elution and has a sufficient active period for industrial use.

[Brief explanation of the drawing]

Figure 1 a and b show the initial oxidation degree of 72% when the titanium content is 2.0 mol% in the nickel oxide-titanium system.
FIG. 3 is an X-ray diffraction diagram of the electrode coating of FIG. Figure 2 a and b show that the raw materials nickel oxide powder and titanium oxide powder are mixed so that the titanium content is 2 mol%.
It is an X-ray diffraction pattern obtained by crushing and measuring. FIG. 3 is a graph showing the relationship between the hydroxide production ratio and hydrogen overvoltage after electrolysis in Examples 1 to 12 and Comparative Examples 1 to 9. Measurement conditions Target Cu KV-mA 40-150 Filter Monochromator Full! 3calc O. 8 ~ 30X 103c
ountTimeContant 2secSca
n. Spaad l” /IIlinChart Sp
eed lcm/minDetector S. C

Claims (1)

[Claims] (1) In a hydrogen generation electrode in which a conductive base material is coated with an oxide of at least one metal selected from nickel and cobalt, 0.1 to 3.0
Contains mol% titanium as solid solution and 35%, 9
In an alkaline aqueous solution at 0°C, the coating was heated at 0.2 mv/se from the hydrogen generation potential to 0 mv (vs, NHE).
An electrode for hydrogen generation, characterized in that the generation ratio of nickel and/or cobalt hydroxide defined as below is 15% or less when the potential is scanned at c. Hydroxide production ratio=H_1/H_0+H_1×100(
%) H_0: Height of main strength of metal measured by X-ray diffraction method. If the coating contains two or more metals, the sum of the respective principal strengths. H_1: Height of main intensity of metal hydroxide measured by X-ray diffraction method. If the coating contains hydroxides of two or more metals, the sum of the principal strengths of the respective metal hydroxides.