JPS5925985A - Low overvoltage cathode having high durability and its production - Google Patents

Abstract

PURPOSE:To obtain a low overvoltage cathode having high durability, by using the alloy compsn. consisting of three components; X; Ni or Co, Y; Al, Zn, Mg or Si, Z; noble metals or Re in the range enclosed of specific four points in the diagram. CONSTITUTION:A three components alloy consisting of component X; (Ni or Co), Y(Al, Zn, Mg or Si), and Z(noble metals or Re) is used. The compsn. is within the range enclosed by the following points A, B, C and D of the diagrams consisting of the three components of X, Y and Z. The compsn. is, by weight %, A(X=99.6, Y=0, Z=0.4) B(X=79.6, Y=20, Z=0.4) C(X=40, Y=20, Z=40), D(X= 40, Y=0, Z=60). The electrode active metallic particles consisting of the alloy having such compsn. are dispersed uniformly in a plating bath and the alloy layer thereof is provided on an electrode core by a co-electrodeposition, coating, dipping, baking, or electroplating method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly durable and low overvoltage cathode, particularly to a cathode having extremely low deterioration in characteristics even in an oxidizing environment, and particularly having low hydrogen overvoltage characteristics, and a method for producing the same.

Various types of low hydrogen overvoltage negative electrodes, particularly cathodes for electrolysis, have been proposed. Among these, the electrode disclosed in Japanese Unexamined Patent Publication No. 112785/1985, which the applicant had already proposed, has great effects in terms of lower hydrogen overvoltage and durability compared to the previously known 7vL electrode. However, as a result of further investigation, the present inventors further determined that
The present invention was completed by discovering an electrode with low overvoltage and improved durability and a method for manufacturing the same.

Producing oxygen scum from the anode chamber and hydrogen scum from the cathode chamber by electrolysis in a caustic alkaline aqueous electrolytic cell is already a well-known industrial method for producing oxygen and hydrogen. As the cathode of this electrolytic cell, the above-mentioned cathode with low hydrogen overvoltage is preferably used, but during operation of the electrolytic cell, operation may be stopped for various reasons, and in this case, operation must be restarted. As a result, it was found that the hydrogen overvoltage increased by 1. As a result of our deep investigation into this phenomenon, the inventors found that
The nickel or cobalt of Raney nickel particles or 2Neko/Kult particles, which are electrode active ingredients, is transformed into nickel hydroxide or cobalt hydroxide, thereby deteriorating the stain generality (that is, increasing the hydrogen overvoltage). In order to prevent this deterioration, known metal particles consisting of a first component such as nickel or cobalt and a second component such as aluminum, zinc, magnesium or silicon are combined with a third component, It is found that containing a component selected from rhenium has a remarkable effect, that an electrode having a surface layer with the same composition instead of particles has a similar effect, and that the hydrogen overvoltage of the first and second The present invention has been completed by discovering that the amount is even lower than when it is composed of only the components. An alloy for water electrolysis consisting of component Y and component 2 selected from noble metals and rhenium, where components X, Y, Z are in the range surrounded by points A, B, O, and D in Figure 1. Highly durable low hydrogen overvoltage cathode, on the electrode core, an alloy consisting of a component x 1 consisting of nickel and/or cobalt, a component Y selected from aluminum, zinc, 1 gnecum, silicon, and a component 2 selected from a noble metal, rhenium. , components x, y
, z is in the range surrounded by points A, B, O, and D in FIG. Electrode active metal consisting of an alloy in which component Y1 selected from aluminum, zinc, magnesium, and silicon and component 2 selected from noble metals and rhenium are in the range surrounded by points A', n', o', and D' in FIG. Either the particles are uniformly dispersed in the plating bath and co-electrodeposited on the electrode core, or
The subject matter is a method for producing a high-reliability, low hydrogen overvoltage cathode for water electrolysis, which is characterized by providing a uniform layer of the above-mentioned alloy on an electrode core by a coating method, dipping method, baking method, or electroplating method. It is something to do.

Here, the precious metals include gold, silver, and platinum metals (i.e., platinum, rhodium, ruthenium, palladium,
iridium).

Here, FIG. 1 shows a three-component diagnosis consisting of a component x1 consisting of nickel and/or cobalt, a component Y selected from aluminum, zinc, magnesium, and silicon, and a component Y selected from noble metals and rhenium. The alloy composition of the alloy layer in the cathode is indicated by points A, B, O, and D in Figure 1.
It must be within the range enclosed by .

Preferably, the range is A, B, Fi, F.

Here, the values of the (x, y, z) components at points A, B, O, and D are A(99, 6, 0, 0.4), respectively, in weight percent.

B(79,6,20,[1,4),0(40,20°4
0), D(40,0,6D), and points A, E,
Ft, FC7) (X, Y, Z) component layers are A(99,6,0,0,4) and E(79,120) respectively in weight%.
, [1,4), x(6o, 20°20), F(80,0
, 20).

The effect of the present invention is due to the inclusion of a component selected from noble metals and rhenium as one component of the alloy composition, but it is believed that the inclusion of these components prevents the formation of hydroxides of nickel (nickel or cobal). The details of whether this is possible have not yet been clarified. However, the present inventors have found that among these components, platinum, rhodium, and ruthenium are most suitable for achieving the effects of the present invention.

That is, among metals, when platinum, rhodium, and ruthenium are used, an especially low hydrogen overvoltage can be maintained for a long period of time even under severe environmental conditions.

It is preferable that the alloy of the cathode of the present invention has a composition surrounded by ABCD in FIG. This is because even if the eel is made to contain a higher concentration of hydrogen, precious metals, or rhenium components beyond this range, the expected low hydrogen overvoltage and durability will hardly change.

When the above-mentioned alloy is in the form of particles, the average particle size is related to the porosity of the electrode surface and the dispersibility of the particles during electrode manufacture, which will be described later, but it is sufficient that the average particle size is α1μ to 100μ.

Within the above range, from the viewpoint of the porosity of the electrode surface, it is preferably 09 μm to 50 μm, more preferably 1 μm to 50 μm.

Furthermore, the layer of the alloy of the present invention is preferably superficially porous in order to achieve a lower hydrogen overvoltage of the electrode.

When the alloy is a particle, this surface porosity does not only mean that the entire surface of the particle is porous, but also that only the portion exposed from the metal layer mentioned above is porous. In addition, if the alloy is provided in a layered manner on the electrode core, such as a plating layer,
The layer is porous due to unevenness, etc. : Power is all you need.

As for the degree of porosity, it is preferable that the degree is as large as possible; however, if the degree of porosity is excessively large, the mechanical strength of the electrode layer decreases, so it is preferable that the porosity is 20 to 90 inches. The above range 9 is more preferably 35
-85%, particularly preferably 50-80%.

Note that the above porosity is a value measured by a known water displacement method. Various methods can be used to make the alloy porous, but regardless of whether the alloy is in the form of particles or not, for example, from an alloy consisting of components X, Y, and Z, part or all of the metal of component Y can be used. Preferred is a method in which the material is made porous by removing it.

In such a case, a particularly preferred method is to treat an alloy in which components X, Y, and Z are uniformly blended in predetermined proportions with caustic alkali treatment to remove at least a portion of the metal of component Y. In the case of the cathode of the present invention, for example, when used as a cathode for producing hydrogen by water electrolysis of a caustic alkaline aqueous solution, it is not necessarily necessary to treat it with caustic alkali before installing it in an electrolytic cell, and the cathode is not necessarily used. Because the catholyte used is caustic,
During electrolysis, the metal of component Y is gradually removed, and it can serve as the intended cathode.

Various combinations of compositions of the metal particles can be used, typical examples include Ni-A1-Pt
, Ni-Al-Rh, Ni-Al-Ru
, Ni-Zn-Pt, Ni-Zn-Rh
, Ni-Zn-Ru, Ni-day 1-P
t, Ni-81-Rh, Ni-day 1-
Ru, 0o-A'1-Pt.

Co-Human'1-Rh, 0o-Al-Ru,
0o-Zn-Pt, 0o-Zn-Rh
, Co-Zn-Ru, 06-8i-Pt
, 0o-Eli-Rh, Co-Eli-R
u, Ni-Mg-Pt, Ni-Mg-Rh
.

Ni-Mg-Ru, Oo-Mg-Pt,
Possible examples include Oo-Mg-Rh and Oo-Mg-Ru.

Among these, a particularly preferable combination is Ni-Al-Pt
, Ni-Al-Rh, Ni-A1-Ru,
0o-Al-Pt.

0o-AI-Rh, 0o-Al-just U.

In addition, the conditions for caustic treatment vary depending on the composition of the starting alloy, but in the case of an alloy with the composition described below, the caustic alkali concentration (Mail conversion) 1 (] to 35 weight Ji-1 10 to 50 °C It is preferable to immerse in this solution for 0.5 to 3 hours.The above conditions were selected to make component Y as easy to remove as possible.

In addition, component 2 is a component that is not removed by the alkali treatment, but even if it is removed, it is a small amount.

When the above-mentioned alloy is in the form of particles, the layer for firmly providing the particles on the metal core is preferably made of the same metal as component X constituting the alloy particles.

Thus, a large number of the above particles adhere to the electrode surface of the cathode of the present invention, and macroscopically, the cathode surface becomes microporous.

The same applies to the case where the surface of the electrode core body is uniformly coated with an alloy metal, but unlike the case where alloy particles are used, there is no metal layer serving as a binder.

Thus, in the cathode of the present invention, the electrode surface is coated with an alloy containing nickel and/or cobalt, which itself has a low hydrogen overvoltage, and as described above, the electrode surface has a microporous trap. Therefore, the active surface of the electrode becomes larger accordingly, and the synergistic effect of these makes it possible to effectively reduce the hydrogen overvoltage.

Furthermore, in the case of using alloy particles in the present invention, since they are firmly attached to the electrode surface by the layer made of the metal, they are not susceptible to deterioration due to falling off, and the durability of the low hydrogen overvoltage described above is particularly excellent. ing.

The material of the electrode core of the present invention may be any suitable conductive metal, such as Ti r Zr or Fe.

Ni+ V+ Mo+ Ou, Ag+ Mn+
platinum group metals.

A metal selected from graphite + Or or an alloy selected from these metals may be employed. Of these, Pe.

Pe alloy (Fe-Ni alloy, Fe-Or alloy, F
e-IJi-Or gold alloy), Ni, Ni alloy (Ni-
(Ou alloy, N1-0r alloy, etc.), Ou, Ou
It is preferable to use gold alloy. Particularly preferable electrode core materials include Fo, Ou, Ni + Fe-Ni
Alloy, Fe-Ni-Or alloy.

The structure of the electrode core can be made into any suitable shape and size depending on the structure of the electrode used.

The shape may be, for example, plate-like, porous, net-like (for example, expanded metal), or slat-like, and these may be flat, curved, or cylindrical.

The thickness of the layer of the present invention is sufficient if it is 20 to 200μ,
More preferably 25 to 150μ, particularly preferably 30 to 150μ
It is 100N.

Cross-sectional views of the electrode surface of the present invention are shown in FIGS. 2 and 3.

As shown in FIG. 2, a layer 2 made of metal is provided on the lightning pole body 1 via an intermediate M4, and a portion of the electrode active metal particles 3 are placed on the surface of the layer. It is included in such a way that it is exposed.

However, the proportion of particles in layer 2 is preferably 5 to 80 wt%, more preferably 10 to 50 wt%. Between the frost, the polar core and the layer containing alloy particles, Ni,
The durability of the electrode of the present invention can be further improved by providing an intermediate layer made of a metal selected from Co, Ag, and Ou.

Such an intermediate layer may be of the same type or a different type from the metal of the above-mentioned layer, but from the viewpoint of adhesion between the intermediate layer and the above-mentioned layer, these intermediate layers and the metals of the layer are of the same type. It is preferable. The thickness of the intermediate layer is preferably 5 to 100 μm from the viewpoint of mechanical strength, etc., more preferably 20 to 80 μm, particularly preferably 30 to 50 μm.
It is.

Of course, it is not always necessary to provide the intermediate layer as described above.

FIG. 6 is a cross-sectional view of the cathode of the present invention in which the surface of the electrode body is uniformly coated with an alloy layer, where 1 is an electrode core and 5 is a uniform surface layer of an alloy with electrode activity. , 6 is the middle layer.

In the electrode of the present invention shown in Fig. 2, a large number of particles are exposed on the electrode surface, but the surface layer is porous mainly due to the gaps between the particles, and the alloy component Y is The voids after removal also contribute to the porosity.

As mentioned above, the degree of porosity is also related to the decrease in hydrogen overvoltage, so the degree of porosity is 1000 p in electric double layer capacity.
F/cm" or more can sufficiently achieve the purpose.

The above range 9 is preferably 2000 μF 7cm2 or more, particularly preferably 5000 plP/cm” or more. Electric double layer capacity is defined as the electric double layer capacity when positive and negative ions travel a short distance near the electrode surface when the electrode is immersed in an electric MffL solution. It is the electrostatic capacitance of electric double layers formed in a relatively distributed manner, and more specifically, it shows the actually measured differential capacitance.

This capacitance increases as the electrode surface becomes larger.

Therefore, when the electrode surface becomes porous and the surface area of the stain electrode increases, the electric double layer capacity of the electrode surface also increases. Therefore,
The electric double layer capacity determines the electrochemically effective electrode surface area, that is, the degree of porosity of the electrode surface.

Note that the electric double layer capacity varies depending on the temperature at the time of measurement, the type of electrolyte solution, the concentration, the electrode potential, etc., so the electric double layer capacity of the present invention means a value measured by the following method.

The test piece (electrode) was soaked in a 40 wt% Na0II aqueous solution (
A black platinum plate with an apparent area approximately 100 times that of the test piece is inserted as a counter electrode, and the cell impedance in this state is measured with a vector impedance meter to determine the electrical resistance of the test piece. Find the layer capacity.

Various methods are adopted as specific means for forming the electrode surface layer, such as dispersion plating method, melt coating method, baking method,
Alloy plating method, molten liquid immersion method, etc. are used.

When using alloy particles, a dispersion plating method is particularly preferable because the particles of the present invention can be deposited well.

Dispersion plating is a method in which plating is performed using an electrode core as a cathode in an aqueous solution containing the metal that forms the metal layer, for example, a bath in which alloy particles mainly composed of nickel are dispersed. , the above metal and alloy particles are co-electrodeposited.

In more detail, the particles become bipolar in the bath due to the influence of the lightning field. When they approach the cathode surface, they increase the local current density of the plating, and when they come into contact with the cathode, they become bipolar. It is thought that the metal plating is co-electrodeposited on the core body by ion reduction. For example, gold F%
When a nickel layer is used as the layer, a total nickel chloride bath, a high nickel chloride bath, a nickel chloride-nickel acetate bath, etc. can be used. In addition, when adopting a cobalt layer as a metal layer, a total cobalt chloride bath, a high cobalt chloride bath,
A bath of iobaltyl chloride and cobalt acetate can be used.

In this case, the pH of the bath is important. In other words, the electrode active metal particles dispersed in the plating bath generally have oxygen attached to their surfaces, and in this state, the bonding with the metal layer is insufficient, and the particles may In order to prevent this, it is necessary to reduce the amount of oxygen attached to the surface of the particles. It is preferable to set it to ~50.

In the case of the present invention, the metal particles include component X consisting of nickel and/or cobalt, aluminum, zinc,
Component Y selected from ignesium and silicon and component 2 selected from noble metals rhenium are at point A' in Figure 4,
It is necessary that the alloy be in the range surrounded by B', O' and D'.

In addition, A', B', O', D' in Fig. 4
The alloy components (X, y, z) are A'(59
, 8° 40.11.2), B'(39, 8, 60, [1
2), C'(5,60,!55), D'(12,40,
48).

More preferable ranges are A', B', F
! '.

y, A': (59, 8, 40, α2), B'
: (59, 8, 60, α2), i': (so, 6o.

10), F': (50, 40, 10). The reason for this is that if it deviates from this range, it may not be possible to secure a sufficient amount of adhesion during the electrodeposition process, or even if electrodeposition is possible, the adhesion strength will be low. This is because the activity as an electrode catalyst is not sufficient.

Alternatively, even if the amount of noble metal components considerably exceeds this range, the effect of reducing limescale overvoltage and the durability of copper will not be significantly improved.

As mentioned above, it is preferable that the amount of oxygen attached to the surface portion of the particles in contact with the gold IA layer is small from the viewpoint of adhesive strength of the particles, but on the other hand, such particles co-electrodeposited on the electrode core are It is preferable to form an oxide film partially on the surface for stabilization. The oxide film deposited on such particles is reduced and removed by generated hydrogen when the electrode is used as a cathode for electrolysis of an aqueous alkali chloride solution or the like. Before use as this outer electrode, such oxide film is reduced (e.g. heated in a hydrogen atmosphere).
It can also be removed.

The proportion of such particles in the bath is between 17/l and 2001/l.
l, especially 1 f/L to 50 Da/1. Furthermore, 11/l~1
It is preferable to keep the temperature at 0 t/lKL from the viewpoint of improving the adhesion state of particles to the electrode surface. In addition, the temperature conditions during dispersion plating work are 20~80℃, especially 30~60℃,
The current density is preferably IA/am" to 20 jJeLm", particularly 1 A/dm2 to 10 A71 m".

It goes without saying that additives for strain reduction, additives for promoting co-electrodeposition, etc. may be added to the plating bath as appropriate.

As mentioned above, when providing an intermediate layer between the electrode core and the metal layer containing particles, the electrode core is first plated with N1, CO, or Ou, and then the dispersion plating method described above is applied. A metal M containing particles is formed thereon by means of melt spraying.

As the plating bath in such a case, the various plating baths mentioned above can be used, and also for O plating, a known plating bath can be used.

In this way, an electrode is obtained in which the particles of the present invention are attached to the electrode core via a metal layer.

Next, specific means for providing the alloy layer having uniform electrode activity on the electrode core will be explained.

Specific methods for forming the film include the above-mentioned passing through, coating method, dipping method, baking method, electroplating method, and the like.

The coating method is preferably a method of melting and spraying a thin rod or powder of the alloy shown in Fig. m14. For this melt spray, a Gutsuzumi spray device, an oxygen-hydrogen flame, an oxygen-acetylene flame spray device, etc. commonly used in the melt coating method can be used.

The immersion method is a method in which an electrode core is immersed in a molten liquid of the above alloy to form a coating layer of the alloy on the core, and the temperature of the molten alloy is 50 to 200°C below the melting point of the alloy. Higher temperatures are better. In the case of N1-mu1-Ru, the melting point is about 1500
℃, it is preferable to form an alloy coating layer on the electrode core by dipping and pulling at about 1600℃.

In the baking method, pre-prepared fine powder particles with a Q particle size of 100μ or less are applied to the electrode core using an appropriate polymer compound, especially a water-soluble polymer aqueous solution as a binder, and then heated to bake the binder. This method involves volatilizing the particles, sintering the particles, and fixing them to the substrate. 10 above the normal melting point
Sintering is preferably carried out at a lower temperature of 0 to 300° C. and preferably under pressure.

In the electroplating method, a solution (preferably an aqueous solution) of a metal salt having the components X, Y, and Z in the range shown in Figure 4 is prepared, and the electrode core is immersed as a cathode in this solution to perform electroplating. This is the so-called alloy plating method. However, Y is Al
, Mg, this method cannot be adopted, but it is possible when Y is Zn. Conventional plating conditions may be used, for example, NiSO4.7H20, ZnSO4.

F) Ni-Zn-Re by setting a mixed solution of KR004 and (NH4)2E104 at pH-40 and plating at a current density of about I A/am'' and a temperature of about 60°C.
can form an alloy layer of

It is also effective to attach a non-electronically conductive substance to the surface of the low hydrogen overvoltage cathode thus obtained.

When the cathode of the present invention is used, for example, as a cathode for water electrolysis of a caustic aqueous solution, iron ions or iron-containing ions eluted from the surrounding container material may be present in the catholyte, and these may be present on the cathode. A discharge may occur and iron compounds (eg iron hydroxide) may be deposited on the cathode. In this case, the active surface of the cathode is lost and the cathode overvoltage increases.

In order to prevent such discharge deposition, a non-electronically conductive material such as a fluorine-containing resin (such as PTF, etc.) is applied to the cathode of the present invention, and furthermore, metal particles protruding from the surface of the cathode are used. It is effective to attach it to the top.

As a concrete means for this purpose, the patent application No. 56-1269
A method such as that disclosed in No. 21 may be suitably employed.

The resulting cathode is then treated with caustic alkali (e.g., immersed in an aqueous caustic solution) as necessary to elute and remove at least a portion of the metal of component Y in the alloy particles, thereby removing the particles or the electrode surface layer. to make it porous.

The conditions in such a case are the above-mentioned conditions.

If an alloy of the above-mentioned components X, Y, and Z is used, it is preferable to perform the caustic alkali treatment as described above. ' You may attach it to the M tank and actually perform electrolysis.

In such a case, the metal of component Y is eluted during the electrolysis process, and the overvoltage of the electrode is reduced. However, although the caustic alkaline aqueous solution is slightly contaminated by the eluted metal ions of component Y, this generally does not pose a problem.

Next, examples of the present invention will be described.

Examples 1 to 16 Alloy powder (200 mesh passes) having the composition shown in Table 1 was prepared and used in Examples 1 to 10.
2, and for Examples 11 to 13, the N i O:tl·6 H2O of Example 12 of the same publication was changed to 0oO1
2./+H20 (concentration 500 r/l), a dispersion plating method based on a plating method in which the Ni plate anode was replaced with a CO plate anode (however, the development treatment temperature after plating was 50°C).
A low hydrogen overvoltage electrode was manufactured using the following method.

A part of the metal particles on the obtained electrode was peeled off and its composition was investigated. The results are also listed in Table 1.

Next, these electrodes were used with a nickel plate as the anode and a fluorine-containing cation exchange membrane (0F-OF manufactured by Asahi Glass, and 0F).
A short circuit resistance test was conducted using 2-OFO (OF, ), 0OOOH3 and O copolymer, ion exchange capacity L 45 meq/f resin) as a cathode for a water electrolyzer for a caustic alkaline aqueous solution as an ion exchange membrane. Ta. The following short circuit test was carried out on the third day after the start of electrolysis using a 25% NaOH aqueous solution as the anolyte and a 35% NaOH aqueous solution as the catholyte at 90°C and a current density of 20 A/am''.

1. First, stop the power supply from the DC power supply, connect the anode and cathode outside the battery case using copper conductive wire, and leave it for about 1 hour.
It took 5 hours. During this time, we observed the current flowing from the peduncle to the anode. The catholyte temperature was maintained at 90° C. for about 3 hours after electrolysis was stopped, and then allowed to cool naturally. Do this operation 5
After being turned over several times and left to cool for 15 hours, the electrode was taken out and the hydrogen overvoltage was measured. Table 1 shows the results. This is almost the same as the pre-test performance.

In addition, the electrode of Example 6 was placed in a 50-inch NaOH aqueous solution for 1 hour.
It was soaked at 40°C for 3 weeks. In order to ensure sufficient contact with air (81), the depth of the container was shallow to f 7 ers, and the top of the container was open. The hydrogen overload and pressure of this electrode were measured before and after the immersion test. The hydrogen overvoltage was 0.09 V. There was almost no change before and after the test.

Comparative Examples 1 to 2 Comparative Example 1 follows Example 12 of JP-A-54-112785, and Comparative Example 2 uses NiO12.6H20 in Example 12 of the same publication as 0001, -6111.
20 (a degree 300f/A), a Ni plate anode was placed at 00
Based on the different plating methods for plate anodes, 1
Ji-Al and Oo-A1 alloy powder dispersion plated electrodes were manufactured.

A part of the metal particles on the obtained electrode was peeled off and its composition was investigated. The results are also listed in Table 2.

A short circuit test was conducted in the same manner as in Examples 1 to 16, and changes in hydrogen overvoltage before and after the test were measured. The results are shown in Table 2 together with the measured hydrogen overvoltage values before the test.

Comparative Examples 5-6 A cathode was produced in the same manner as in the example except that the composition of the alloy powder was changed to Comparative Examples 6-6 shown in Table 2. Table 2 shows the results of a short circuit test conducted in the same manner as in the examples.

Comparative Examples 3 and 4 show that no particular performance improvement is observed even when a large amount of the third component is added. Comparative Examples 5 and 6 show that the overvoltage was initially higher because the metal composition of the raw material powder was outside the preferred range.

Table 1 Table 2

[Brief explanation of drawings]

Figure 1 shows X-Ni or tJ:ao, Y-111AI
, zn. The composition in the range surrounded by dots B, C, and D in the diagram consisting of the three components Mg or Si, Z-noble metal, or rhenium indicates the composition of the alloy having electrode activity in the cathode of the present invention. FIG. 2 is a partial cross-sectional view of the surface of an example of the electrode of the present invention, and FIG.
The figures each show a partial cross-sectional view of the surface of another example of the electrode of the present invention. Figure 4 shows X-Ni or Co, YI=IIAl
, Zn. Mg'51tJ: st, z = 3 of noble metal or rhenium
In the diagram consisting of the components, the points A/, nl,
c1. The composition range surrounded by D I indicates the composition range of the electrode active alloy used in the method of the present invention. 0D -x ('/D7'+7 order. ;23rd

Claims (1)

[Claims] (11-" An alloy consisting of a component x1 consisting of Kel and/or cobalt, a component Y selected from aluminum, zinc, 1gnesium, and silicon, and a component Y selected from noble metals and rhenium, Components X, Y, and Z are points A and B in Figure 1.
A highly durable, low overvoltage cathode consisting of an alloy in the range enclosed by %0 and D. A: X-99,6wt%, Y-0wt%,
Zmo, 4wt% B: X-79, 6wt%,
Y-20wt%, Z-0,4wt Chi0: X-40
wt%, Y-20wt%, Z=40wt%D:
XIe! 40 wt%, Y-0wt%, Z-
60wt% (2) On the electrode core, an alloy consisting of component x1 consisting of nickel and/or copper, component Y selected from aluminum, zinc, magnesium, 7 licon, and component 2 selected from noble metals and rhenium. So, ingredient X
, Y, and Z are provided with alloy scraps in the range surrounded by points A, BXO, and D in FIG. 1. A: X=99.6wt%+Y-[1vrt%e
Zmo, 4wt%B: X-79,6wt%, Y
-20wt%, Z=[14wt%0: X740
wt%+Ye=20vrt%, Zw40wt9
6D: X+m40 wt%+YW owt4
Claim (2): The layer of Z-60wt% (3) alloy is formed by exposing some of the particles of the alloy to the surface of the scrap provided on the electrode core. Highly durable low overvoltage cathode. (4) Component x consisting of nickel and/or cobalt
1. An active electrode consisting of an alloy in which a component selected from aluminum, zinc, and magnesium and a component 2 selected from a noble metal and rhenium are in the range surrounded by points A, nf, of, and D' in FIG. Metal particles are uniformly dispersed in a plating bath and co-electrodeposited on the electrode core, or applied to the electrode core by coating, dipping, baking, or electroplating. A method for producing a highly durable and low overvoltage cathode characterized by providing a layer of an alloy. A-': X-59, 8wt%, 'f-40wt%,
Z-0,2wt%B': X=39.8wt%,
Y ==60wt%, Z-0, 2wt%0':X-
5wt%, Y-60wt%, Z=35wt%D
': X=! -12wt%, Ye=40wt%,
Z=48wt% (5) Claim No. 4, wherein the coating method is a method of spraying the alloy particles onto the electrode core.
) Method for manufacturing highly durable and low overvoltage cathodes. (6) The method for producing a highly durable, low overvoltage cathode according to claim (4), wherein the immersion method is a method of immersing an electrode core in a molten liquid of the alloy. (7) The method for producing a highly durable and low overvoltage cathode according to claim (4), wherein the electroplating method is an alloy plating method. (8) The method for producing a highly durable, low overvoltage cathode according to claim (4), wherein the plating bath contains metal ions of the same type as the components. (9) The method for producing a highly durable, low overvoltage cathode according to claim (4) or (8), wherein the plating bath has a pH of 1.5 to 50. (II) An alloy layer provided by co-electrodeposition, dipping, coating, baking or electroplating with NaOH concentration of 10 to 3.
0.5 in a caustic soda aqueous solution at a temperature of 10 to 50°C
The method for producing a highly durable and low overvoltage cathode according to claim (4), wherein the treatment is performed for ~3 hours.