JPS5842781A - Production of electrode - Google Patents

Abstract

PURPOSE:To produce a cathode of low hydrogen overvoltage in electrolysis by forming an Ni plating layer dispersed with particles of porous Ni, Co, etc. on Fe as the cathode to be used for electrolysis of an aq. soln. CONSTITUTION:As a cathode to be used in the stage of electrolyzing an aq. NaCl soln. by a diaphragm method electrolytic cell, metals having high conductivity such as Fe, Ni, Cu or Fe-Ni, Fe-Ni-Cr or the like are used for a core body 1 of an electrode, and said body is electroplated in a nickel chloride soln. of 135g/l concn. dispersed with particles 3 of 0.1-100mu diameters made of an alloy of the 1st metal selected from Ni and Co and the 2nd metal selected among Al, Zn, Mg, Sn, whereby an Ni plating layer 2 dispersed with the particles at 5- 80% ratio is formed. Said body is dipped in an aq. caustic alkali soln. of NaOH or the like to dissolve away part of the 2nd metal such as Al in the particles 3, whereby the porous layer of >=1,000muF/cm<2> capacity of the electric double layers is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION 4hO''tI relating to low overvoltage O electrodes used in aqueous liquid electrolysis, especially cathodes with low water bulk overvoltage O.
Toru.

For example, when an aqueous alkali chloride solution is subjected to electric shock to produce caustic alkali and salt, an electrolyzed aqueous solution is electrolyzed to obtain an electrolyzed product, and an 11-O corrosion-resistant electrode is used. II for electrolyzing such electrode wires and aqueous liquids such as aqueous alkali chloride solutions.
By lowering the generated overvoltage as much as possible, electricity costs can be reduced, and electrolysis products can be obtained at a correspondingly lower cost.

For this reason, various studies have been conducted on the materials and processing methods for anodes in order to reduce the chlorine overvoltage of the anodes, and some of them have already been put into practical use. Since the development of the partitioning method in which electrolysis is carried out at the cathode through a wire or diaphragm, there has been a demand for electrodes with low water bulk overvoltage and alkali resistance. Iron is used as the cathode in the nonachloride alkaline water S* electrolysis using a diaphragm that is currently practiced.

And further lower the #O hydrogen overvoltage by -1 on the iron surface.
It has also been proposed to apply Ndoplast treatment II (for example, the treatment method shown in [Surface Treatment Handbook] by Eimei Tajima, published by Douji Tosho, pp. 41-542). However, the asbestos membrane method has the disadvantage that the obtained asbestos soda has a low starvation degree of about 10 to 1wt bags, and that salt is mixed in as an impurity in the aqueous solution of gastric soda. A method of electrolyzing an aqueous alkali chloride solution using a membrane as a diaphragm has been developed and is being industrialized. According to such a method.

It is possible to obtain high concentration zero caustic soda of 25 to 4 degrees vtd without the contamination of salt as an impurity. In such cases, if conventional iron is used as the electrode, the concentration of caustic soda is high, and the electrolytic temperature is as high as 80 to 120°C. Some of the iron dissolves into the catholyte, causing problems such as loss of product purity.

The present inventor has discovered a method for producing an electrode O that uses a material that is more resistant to corrosion by 4hw alkalis than iron, effectively lowers hydrogen overvoltage, and maintains this effect for a long time, and has developed the present invention. provide.

Thus, the present invention provides a method for producing an electrode in which particles containing at least one metal selected from nickel, 1 part, and 0 metals are deposited on an electrode stone body through a layer made of nickel. Nickel chloride (aicx!-6a, o
The gist of this is a method for producing an electrode O, which is characterized by plating by immersing the electrode core in a nickel plating bath containing nickel chloride at a concentration of 135 t/L or higher.

A large number of particles are attached to the surface of the electrode obtained by the present invention, and when viewed macroscopically, the electrode surface is microporous.

The electrode wire thus obtained by the method of the present invention.

A large number of particles containing nickel and cobalt, which themselves have a low hydrogen overvoltage, exist on the electrode surface m, and the above-mentioned excessive
Because the electrode surface is microporous, the active layer of the electrode is thicker1).

These synergistic effects make it possible to effectively reduce hydrogen overvoltage. Moreover, according to the method of the present invention:
Since the concentration of nickel chloride in the O method is much higher than that in the conventional O method, the oxygen present on both sides of the particles is removed in the O method, and the surface of the particles is cleaned. Since these particles are firmly attached to the electrode surface by the layer made of the above-mentioned metal, they are difficult to deteriorate, and the sustainability of the above-mentioned low hydrogen overvoltage can be dramatically extended. Furthermore, the initial performance of the electrode O obtained (by the above effect) is also improved.

The material of the ninth electrode core for carrying out the method of the present invention may be any suitable conductive metal such as Te1゜Zr, ν@, I
X-rays of metals selected from i, V, MO, On, Mg-Mn *Platinum group metals, graphite, Or Nine alloys different from these O metals can be adopted. We within ζO? @Alloy F@-111 alloy *Fe-0r alloy, C@-11
-Or gold alloy etc.)lii, ]lii alloy (Ml-Ou
Gold alloy 111-Or gold alloy etc.) OEI.

It is preferable to use On alloy or the like.

A particularly preferable material for the electrode core is 1.Ou.

1i1. ? There is the e-111 alloy and the 1-Or gold alloy.

The electrode core O structure IIi can have any suitable shape and size depending on the electrode O structure used.

For example, the y#-shaped ore can be in the shape of a plate, a porous shape, a wire shape (for example, ethaspand metal), a violet shape, etc., and these may be shaped into a flat plate, a drawing board, or a cylinder.

In the present invention, the particles containing nickel and cobalt may be particles of these metals alone, particles of a metal alloy mainly composed of these metals, or particles consisting of a composite having a surface layer of these metals or alloys. Ru.

In addition, when a metal 1 alloy mainly composed of the above metals is used, as the O component other than the above metals, metals that do not have an excessively negative effect on the hydrogen overvoltage O reduction can be used, such as M1, although it depends on the O content. The average particle diameter of 0 particles that can be adopted for ゜
w~100P is enough.

Within the above range, preferably from the θ point such as electrode surface O porosity.
Fil 9 p -50p, more preferably 1p-3
0 voice.

Further, in the method of the present invention, it is preferred that the electrode has a rounded surface porosity to achieve a low hydrogen overvoltage.

This surface porosity does not mean only that the entire surface of the particle is porous, but it is sufficient that only the exposed portion of the layer made of good metal described above is porous. .

For the porous o1i11 layer, the larger the degree is, the better it is (however, if it is made too porous, the mechanical strength of the particles will decrease, so the porosity should be 20 to 90.
It is preferable to use the kernels to make a vomit. More preferably 3 within the above range
#i50-80 capsules are particularly preferred.

Note that the above porosity is a value measured by the omniscient O water displacement method.

Various methods can be used to create porosity, such as alloys mainly composed of lli and oo,
, a method of removing gold metal other than OO to make it porous, and a method of converting Ni, 00 into a carbonyl compound and thermally decomposing it.
Method of obtaining porous O metal, method of thermally decomposing Mi,000 organic acid salt to obtain porous metal, method of obtaining porous O metal by heating lIi,ooO oxide in a hydrogen atmosphere, etc. can be adopted. Among these, the workability is O point, Mi, O.

It is preferable to remove metals other than 311.Go from an alloy mainly consisting of 311.
Preferred method 41 is a method in which a metal No. 20 selected from Zn*Mg #am and an O alloy are used, and at least a portion of the metal No. 20 is removed by caustic alkali treatment. Such alloys include Ml-mu, 1li
-jcn4r gold, Ii -Mg alloy, lli -an alloy, Oo-mu 1 alloy% co-jsn alloy, Co -Mg
alloy, Oo-am alloy, and from the point of view of these contents, 'Ii-mu 1 alloy, oO-mu 1 alloy,
is preferred. Such preferred alloys include undeveloped Raney Mickex,
It is Ranney cobalt (Ran5yaobalt). Among these, especially the shoulder 1-mu 1 fee.

Specifically, undeveloped nickel is preferred.

In the present invention, the metal employed in the zero layer to which one particle is attached has alkali resistance.

A metal capable of strongly adhering the particles may be used, but
It is better to use special KNi. In particular, since it is preferable to use the same type of metal as the main metal of the particles to be adopted, the particles should be mainly composed of Ml and 0I.
It is better to implement the present invention in conjunction with II.

The thickness of the layer of the present invention depends on the particle size of the employed particles, but
20 to 200 voices is sufficient, more preferably 25 to 200 voices.
1507m, particularly preferably 30-100μ. This is because, in the present invention, a part of the nine particles described above is attached to the layer KJl made of O metal on the electrode core in a large state.

In order to facilitate understanding of this state, a cross-sectional view of the electrode surface obtained by the present invention is shown in Figure 1g1. As shown in the figure, a layer 2 made of metal is provided on an electrode core 1,
Some particles 30 are in the acid layer.

It is included so that it is exposed from the surface of the layer.

The particle ID in layer 2 is preferably from 5 to a Owt-, more preferably from 10 to S OvtgI. Outside the shape of IlO, the electrode core, a layer containing one particle, and O
Seki %m1. The durability of the O electrode of the present invention can be further improved by providing an intermediate layer made of nine metals selected from Gos, Mug, and On. -1P\ intermediate layer ore, the above layer 0 metal and piIlll [or an intermediate layer, which may be of a different type; It is preferable that the metal #i is the same type as 0.Thickness of the intermediate layer Fi1 Mechanical strength etc. 5 to 100P is sufficient from point O), more preferably 20 to 80P, preferably 50 to ll!f ~50
The cross-sectional view of the electrode is shown in FIG. 2, which is easy to understand when using an electrode with an intermediate layer like μ.

1 is the electrode core, 4 is the intermediate layer, and the layer containing particles from 2 companies is %3Fi.
It is a particle.

The electrode according to the present invention is the first one. As is clear from No. 2, if you look at the surface microscopically, many particles are exposed on the electrode surface, but if you look at it macroscopically, you can see that the porous Kt There is

As mentioned above, the degree of porosity O is #i, the hydrogen overvoltage is 0 decrease K1
Since the m1 is continuous, the degree of porosity and the electric double layer capacity are 1000
If it is 1111F/- or more, the @ target can be fully achieved.

In the above range, it is preferably 1200 pF/am or more, particularly preferably mu<us o o o pv7 or more. Electric double layer capacity is defined as the positive and negative polarities near the electrode surface when the electrode is immersed in an electrolyte solution. This is the capacitance of an electric double iris layer formed by relatively distributing ions separated by a short distance, and more specifically, it shows the differential capacitance observed in practice.

The ζO capacitance increases as the electrode surface becomes larger.

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

Note that the electrical double layer capacity varies depending on the type, concentration, and electrode potential # of the electrolyte solution at zero temperature during measurement.
Electrical two-way capacity means a value measured by the method below.

The test piece (electrode) was 40 wt* 1laoII water S*
(251:) immersed in K, a black platinum plate with an apparent area approximately 100 times that of the test piece was inserted as a counter electrode, and the cell impedance in the ζO state was measured using a Cole 2 Ushini Bridge. Find the double layer capacity.

The present invention provides a method for obtaining an electrode as described above4112
) in a particular plating bath 1(]ii, O.

%0, which is characterized by a dispersion plating method using a plating bath in which metal particles mainly composed of are dispersed. That is, the present invention uses a nickel plating bath in which the torsion of nickel chloride (ntax, 4M, O) is 135 f/ or more, as will be clear from the examples described below. The high concentration of chlorine ions present in the plating bath removes oxygen present on the surface of metal particles and cleans the surface.k
However, the object of the present invention can be fully achieved. By doing so, it becomes possible for the first time to activate the surface of the metal particles and to firmly hold the metal particles in the metal layer on the electrode core.

In the dispersion plating method, plating is performed using an aqueous solution containing the metal forming the metal layer, a bath K in which particles mainly composed of nickel are dispersed, and two electrodes serving as cathodes, and plating is performed on the electrode core. O is also used to co-deposit the metal and the particles.

In order to maintain this dispersed state, the KIri Extremely O method can be employed, and examples include mechanical stirring, gas stirring, a liquid circulation system, ultrasonic stirring, and a fluidized bed.

When a nickel layer is used as the metal layer, a total nickel chloride bath, a high nickel chloride bath, or a nickel chloride-nickel acetate bath can be used.

Next, particles containing a good metal selected from such a bath 4(]ii, Oo are dispersed.The materials and particle sizes of these various particles are as described above.As a single particle, 1/IL, C
The 10th metal selected from o and Mgλ, Zn, Mg,
8! When an alloy of metal No. 20 selected from 1 is used, it is preferable to perform a caustic alkali treatment as described below.

As such alloys, it is practical to use the aforementioned nine materials, undeveloped Tsune Nickel, and Tsune Pal).

In addition, when the above-mentioned first metal is used alone as the particles, it is also possible to remove at least a part of the 20th metal from an alloy of the iris metal and the 20th metal in advance, and in such cases, There is almost no need for the caustic alkali treatment described below. For example, as a 40 like this, it is hot to use Mourning Raney Nickel and 2 Ney Copal F.

The proportion of O-like particles in the bath is %1 t/l~200
It is preferable to leave it at t7tc in order to make the adhesion state of particles on both electrode surfaces even. Also, during dispersion plating work, the temperature conditions are 1j2G to 80℃, and the current density is 1μ/41111.
It is preferable that it is "~20 μm/am".

It goes without saying that the plating bath KFi, additives for strain reduction, additives for promoting eutectoid, etc. may be added as appropriate.

First, in order to further strengthen the adhesion between the particles and the metal layer, is it possible to perform M1 plating again during heating after 1 dispersion plating? -O As mentioned above, if an intermediate layer is provided between the electrode core and the metal layer containing particles, the electrode core must first be coated with Ml, Oo, plating, and Mg.
Me. Then, a metal layer containing particles is formed thereon by the above-mentioned dispersion plating method.

The various plating baths mentioned above can be used as plating baths in such cases, and known plating baths can also be used for O plating.

In this way, an electrode is obtained in which particles are attached to the electrode core through one metal layer.

If necessary, the bales are treated with caustic alkali (for example, immersed in an aqueous caustic solution) to reduce the amount of Mi and O in one alloy particle.
At least a portion of the O40 metal is eluted and removed, rendering the particles porous.

In this case, aqueous caustic solution Om1 degree ore, NaO!
l 5-40wt4j, temperature 50℃~150℃
It is preferable to carry out under the following conditions.

In addition, when the aforementioned alloy of Marugame-9 and the 20th metal is used as the particles, it is preferable to perform the above-mentioned tV-based alkali treatment. Instead, it may be directly deposited in an alkali chloride electrolytic cell and electrolyzed.

In this case, the 20th metal is eluted during the electrolytic O process, and the overvoltage of the electrode is reduced. However, 5ill of produced caustic alkaline water is contaminated by the 20th metal ions that can be eluted.

The electrode of the present invention can of course be used as a cathode in Electron-1III# for electrolysis of aqueous alkali chloride solutions using an ion exchange membrane method. It can also be used as an electrode for water electrolysis.

Next, examples of the present invention will be described.

Example 1 Total nickel chloride bath (11104-4 Summer 50300F/L
%HsBOs 3 II f/l) before O development by Yoken Fine Chemical Co., Ltd. 2N nickel alloy powder □1is
ob, mu15◎9II200 mesh pass) t20t”
With the Mi plate as an anode and the iron plate (electrode core) as a cathode, the current density S O
mA/am'' %pi Lo, !IO minutes at 50°C. As a result, a black-gray plating layer was obtained on the iron plate.

Also, the M1 plating layer can be about 80P (Tot), and the M1 alloy particles in the plating layer can be about 35 wt.

Next, the ζO material was heated in 20-1 Kame OH at 80°C.

Develop for 1 hour and remove the electric double layer capacity #i1
＠ (100p'lr/lym) ``E, tomorrow, hydrogen overvoltage is 601m.

Example 2 High nickel chloride bath (Mi804-411,0200 f
/L%1lio11fist4B10175t/L,
Add 201710 ratio of OjI open nickel alloy powder (Mi50chi, M1solzoo Metsushiepasu) manufactured by Yoken Fine Chemical Co., Ltd. into 140f/f), and stir well to form the Ml plate as an anode and the iron plate (electrode core). as a cathode, the current level is 20 mA/am
Plating was carried out for 1 hour at a pH of 8.45°C.As a result, a black-gray plating layer was obtained on the iron plate.

Mata 1 The plating layer is about 100P〉, and the plating layer is 01
11-mu 1 polymerization number is about 255 tl and there are 6 numerators.

Elute Mu1 using the same method as in Example 1. The electric double layer capacity was 15,000 pv15+3, and the hydrogen overvoltage was #i70 wr.

Example 5 Nickel chloride, nickel acetate bath (1g of irises, 61sO
I S 5 f/L, 111 (OliaOOOO
) 1141m0 105pit) during which Yoken Fine Chemicals 01 Raney nickel alloy was deposited (Mis($
1! , MU15G9120077SI, WBAx) fsof/
Add it to the ltD ratio and add the lli@ to the anode while stirring.

Current density 50mA/a using iron plate (electrode core) as cathode
plating was carried out using w''% pm IO at 50° C. As a result, a black-gray plating layer was obtained on the iron plate.

Also, M1 plated layer wire approx. 40p"ea), plated layer middle 01
11-mu1 alloy particle sister is about S Ovt-.

Mu1 was eluted from this in the same manner as in Example 1. The electric double electric layer capacity is 10000 FF151” and Tol
, hydrogen overvoltage is 80℃.

As can be seen from the above examples, as the degree of nickel chloride tVH in the plating bath increases, the electrode performance improves.

Comparative example Watt bath (1iisO4 salary 71!, OS OOof/l.

MiO14・4H1040f/t, H2BO3S
Of/J! ) Inside is O made by Yoken Fine Chemical Co., Ltd.
Exhibition - Former Raney Nickel Powder (Itiso 哄, Mul 5 [
1 average particle size sOμ) at a rate of 100 f/l,
While stirring this well, use the Mi plate as the anode and the Ou plate (electrode 2).
body) as a cathode, CD30mm/country 1, pHK5.5
The plate was plated at 5° C. for 50 minutes. As a result, a black-gray O plating layer was obtained on the O plate.
k! ! It is clear from microscopic observation that there are many convexities. Komo (Dt-20111 at 80℃ in NaOH
The time was developed and the sample was eluted.

Electric double layer capacitance of plated 90u board Id 5
000 pν/am''.In addition, the electrical double layer capacitance test piece was dissolved in water at 40 vtll 11aoIi (25℃
), insert a platinum black plate with a platinum black plate having an apparent leaf area of 0100 times the test piece as a counter electrode, and measure the O cell impedance in this O state with a Tomi-Leroucier bridge. Find the double layer capacity.

Mataya 1 (approximately 40 plating layers), 0M1 in the plating layer
-Mu1 polymerization number is about ISwt-.

Next, using the plated 90U plate as a cathode,
40 vt%]IaOIi aqueous solution (?OC).

Measure the electrode potential using a saturated electrode as a reference electrode under 20 μm/a-conditions. From this, the hydrogen overvoltage is 1
It was 20 mV.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of the surface of an example of the electrode of the present invention. FIG. 2 is a cross-sectional view of the electrode O and other electrodes of the present invention. Kaya l Kunime 2) Victory

Claims (5)

[Claims] (1) Through a layer of nickel on the three electrodes,
In a method for manufacturing an electrode to which particles containing at least one metal selected from nickel, :I balt are attached,
Nickel chloride (MiOl, -4HmotoL,
``() Electrode O#! Manufacturing method characterized by plating by immersing the electrode core in nickel chloride dispersed in a bath containing nickel chloride having a temperature of 11 degrees or higher. . (2) Particles are a first metal selected from nickel and cobalt, Al-ecum, m-lead,! Claim 1i (1
) electrode 01m manufacturing method. (3) On the electrode core, through a layer consisting of nickel, 41 metals selected from nickel and cobalt, 20 metals selected from aluminum, zinc, magnesium, and tin, and O alloy. (1) A method for manufacturing a 0 electrode, in which at least a part of the metal No. 20 is removed from the particles made of the above-mentioned alloy by adhering the particles and then treating with caustic alkali. (4) The proportion of particles contained in the layer is 5-8Q wt9G
A method for manufacturing an electrode O according to the ranges (1) to (3) of patent lIL, *. (5) Electrode *1 Ik0 electric double electric quantity is 1000Fν/
-8 or more Claims (1) to (4) A method for manufacturing an O electrode.