KR20190037520A - Coating composition for electrolysis cathode - Google Patents

Abstract

The present invention relates to a coating solution composition for an electrolysis anode, which exhibits high efficiency and expresses reduced overvoltage characteristics, and to an electrolysis anode including a catalyst layer derived therefrom. The coating solution composition for an electrolysis anode of the present invention comprises: an alcohol-based solvent; a platinum group metal precursor; a lanthanide metal precursor; and a stabilizer.

Description

[0001] The present invention relates to a coating composition for an electrolysis cathode,

The present invention relates to an electrolysis negative electrode comprising a coating liquid composition for an electrolysis negative electrode and a catalyst layer derived therefrom which exhibits high efficiency while exhibiting an overvoltage reduction characteristic.

Hydrogen, hydrogen and chlorine are produced by electrolysis of low-cost brine such as seawater. The electrolysis process, which is also called chlor-alkali process, is already in operation for several decades. Reliability of performance and technology is a proven process.

Such an electrolytic electrolysis of salt water is performed by an ion exchange membrane method in which an electrolytic cell is divided into a cation chamber and anion chamber by providing an ion exchange membrane inside the electrolytic cell and chlorine gas is used at the anode and brine and hydrogen are used at the cathode It is a widely used method.

Specifically, the electrolysis process of the brine is performed through the reaction as shown in the following electrochemical reaction formula.

Anode reaction: 2Cl ^- -> Cl ₂ + 2e ^- (E ⁰ = +1.36 V)

Cathode reaction: 2H ₂ O + 2e ^- -> 2OH ^- + H ₂ (E ⁰ = -0.83 V)

Overall reaction: ₂ Cl ^- + 2H ₂ O -> ₂ OH ^- + Cl ₂ + H ₂ (E ⁰ = -2.19 V)

On the other hand, in electrolysis of brine, the electrolytic voltage must consider both the voltage required for the theoretical salt electrolysis, the overvoltage of the anode, the overvoltage of the cathode, the voltage due to the resistance of the ion exchange membrane and the voltage due to the distance between the anode and cathode , And the overvoltage caused by the electrode among these voltages is an important parameter.

For example, a noble metal-based electrode called a DSA (Dimensionally Stable Anode) has been developed and used as an anode, and development of an excellent material having a low overvoltage and a durability against a cathode has been developed .

In recent years, stainless steel or nickel has been used as the cathode. To reduce the overvoltage, the surface of stainless steel or nickel is coated with nickel, nickel oxide, a combination of nickel and tin, a combination of activated carbon and oxide, ruthenium oxide, The method to use is being studied.

Further, a method of controlling the composition by using a platinum group compound such as ruthenium and a lanthanide compound such as cerium is also being studied in order to improve the activity of the cathode by controlling the composition of the active material.

For example, Japanese Patent Publication No. 04142191 discloses a negative electrode in which a catalyst layer composed of a lanthanide metal compound and a platinum group compound is formed on a conductive substrate. However, there is a problem that the overvoltage is not sufficiently low and deterioration due to reverse current largely occurs.

JP 04142191 B2

SUMMARY OF THE INVENTION The present invention has been made to overcome the problems of the prior art, and it is an object of the present invention to provide a coating liquid composition for an electrolytic anode capable of exhibiting high efficiency while exhibiting an overvoltage reduction characteristic.

It is another object of the present invention to provide an electrolysis negative electrode comprising a catalyst layer derived from the coating solution composition for an electrolysis negative electrode.

In order to solve the above-mentioned problems, Platinum group metal precursors; Lanthanide metal precursors; And one species selected from sodium dodecyl sulfate, sodium lauryl sulfate, rhodium lauryl ether sulfate, sodium dodecylbenzenesulfonate, trioctylamine, oleylamine, tributylamine, cetyltrimethylammonium bromide and polyvinylpyrrolidone Wherein the stabilizer is contained in an amount of 0.0625 mol to 0.25 mol based on 1 mol of the metal precursor including the platinum group metal precursor and the lanthanide group precursor.

The present invention also relates to a metal substrate layer; And a catalyst layer formed on at least one side of the base layer, wherein the catalyst layer is derived from the coating liquid composition, and the catalyst layer is porous.

The coating liquid composition for an electrolytic negative electrode according to the present invention can form a catalyst layer having a microporous structure and a layered structure by containing a stabilizer in a specific ratio, and the catalyst layer derived from the coating liquid composition may have an increased specific surface area As a result, the electrolytic cathode including the catalyst layer can be improved in the overvoltage.

Therefore, the electrolytic anode containing the coating liquid composition for an electrolytic anode and the catalyst layer derived from the coating liquid composition according to the present invention can be easily applied to an electrolytic decomposition of industry such as salt water.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and together with the description of the invention serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
FIG. 1 shows a scanning electron microscope (SEM) analysis image of a cathode of Example 1 according to an embodiment of the present invention, wherein (a) is a 10,000 magnification image and (b) is a 2,000 magnification image.
FIG. 2 is a scanning electron microscope (SEM) analysis image of a cathode of Example 2 according to an embodiment of the present invention, wherein (a) is a 10,000 magnification image and (b) is a 2,000 magnification image.
FIG. 3 is a scanning electron microscope (SEM) analysis image of a cathode of Comparative Example 1 according to an embodiment of the present invention, wherein (a) is a 10,000 magnification image and (b) is a 2,000 magnification image.
4 is a scanning electron microscope (SEM) analysis image of a cathode of Comparative Example 3 according to an embodiment of the present invention, wherein (a) is a 10,000 magnification image and (b) is a 5,000 magnification image.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed in an ordinary or dictionary sense and the inventor can properly define the concept of the term to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention.

The present invention provides a coating liquid composition for an electrolytic cathode which can be applied to a catalyst layer of an electrolytic cathode to improve the efficiency and the overvoltage of the cathode.

The coating liquid composition for an electrolytic negative electrode according to an embodiment of the present invention comprises an alcohol-based solvent; Platinum group metal precursors; Lanthanide metal precursors; And one species selected from sodium dodecyl sulfate, sodium lauryl sulfate, rhodium lauryl ether sulfate, sodium dodecylbenzenesulfonate, trioctylamine, oleylamine, tributylamine, cetyltrimethylammonium bromide and polyvinylpyrrolidone And the stabilizer is contained in an amount of 0.0625 to 0.25 mol based on 1 mol of the metal precursor including the platinum group metal precursor and the lanthanide metal precursor.

The coating liquid composition for an electrolytic negative electrode according to an embodiment of the present invention is a material used for forming a catalyst layer which is an active layer in an electrolytic anode. The coating liquid composition includes an alcohol-based solvent, a platinum group metal precursor; By including the lanthanide metal precursor and the stabilizer so that the stabilizer is in a specific ratio, the catalyst layer produced therefrom can have a layered structure with a micropore structure. Thus, the specific surface area of the catalyst layer can be increased, and as a result, the overvoltage of the electrolytic cathode including the catalyst layer can be improved. In addition, the coating liquid composition can increase the dispersibility of the platinum group metal precursor as the main active material, and the active particles derived from the white metal in the catalyst layer can be evenly distributed, thereby improving the efficiency of the electrolytic anode including the catalyst layer .

Specifically, the stabilizer may be 0.0625 mol to 0.25 mol per mol of the metal precursor, and more specifically, the stabilizer may be 0.125 mol to 0.25 mol per mol of the metal precursor. If the stabilizer is contained in the coating composition in the above-mentioned ratio range, the stabilizer can be easily dissolved in the coating solution composition, so that the problem of the precipitate does not occur and the catalyst layer having a microporous structure and having a layered structure can be easily . Meanwhile, the metal precursor may be a mixed metal precursor including a platinum group metal precursor and a lanthanide group metal precursor, for example, a platinum group metal precursor and a lanthanide group precursor.

In addition, when the stabilizer is contained in the coating liquid composition beyond the ratio range, the stabilizer may not completely dissolve and may be formed as a precipitate, and it may be difficult to form a catalyst layer using the stabilizer.

In addition, the platinum group metal precursor and the lanthanide group metal precursor may have a molar ratio of 1: 0.1428 to 0.25. That is, the lanthanide group metal precursor may have a molar ratio of 0.1428 to 0.25 mole based on 1 mole of the platinum group metal precursor. If the molar ratio of the platinum group metal precursor to the lanthanide group metal precursor is in the above molar ratio, the activity of the catalyst layer produced from the coating solution composition containing the same can be excellent, and thus, the efficiency of the electrolysis cathode containing the catalyst layer is excellent can do.

In addition, when the platinum group metal precursor and the lanthanide group metal precursor are out of the molar ratio, the activity of the catalyst layer may deteriorate.

In addition, when the coating liquid composition contains the stabilizer in the above ratio and contains the platinum group metal precursor and the lanthanide group precursor in the above-mentioned molar ratio, the specific surface area of the catalyst layer produced therefrom can be easily increased, The overvoltage of the electrolytic cathode including the catalyst layer can be effectively improved.

The alcohol-based solvent may be one or more selected from the group consisting of methanol, ethanol, 1-propanol, isopropanol, 1-butanol and 2-butanol, and may be ethanol.

In addition, the platinum group metal precursor may be a substance that changes into a platinum group metal oxide, which is an active ingredient in the prepared catalyst layer, and may be, for example, a hydrate of a platinum group metal, a hydroxide, a chloride and an oxide. At this time, the platinum group metal may be one or more selected from the group consisting of ruthenium (Ru), rhodium (Rh), rhodium, platinum, iridium, iridium and rhenium In particular, the platinum group metal may be ruthenium.

The lanthanide metal precursor may be a lanthanide metal oxide which is an inactive component in the prepared catalyst layer. For example, the lanthanide metal precursor may be a hydrate of a lanthanide metal, a hydroxide, a chloride and an oxide. The lanthanide metal may be one or more selected from the group consisting of lanthanum (La), lanthanum, cerium, cerium, praseodymium, neodymium, neodymium and promethium And, specifically, the lanthanide metal may be cerium.

In one embodiment of the present invention, in the case of a material containing crystal water as the white metal precursor and the lanthanide metal precursor, the platinum group metal precursor and the lanthanide group metal precursor are each a material in which crystal water is removed ). ≪ / RTI > For example, in one embodiment of the present invention, ruthenium chloride is used as a metal-metal precursor, and ruthenium chloride is a material in which ruthenium chloride hydrate is free of crystal water.

In addition, the stabilizer may be selected from the group consisting of sodium dodecyl sulfate, sodium lauryl sulfate, rhodium lauryl ether sulfate, sodium dodecylbenzenesulfonate, trioctylamine, oleylamine, tributylamine, cetyltrimethylammonium bromide, Polyvinyl pyrrolidone, and more specifically, the stabilizer may be sodium dodecyl sulfate.

The present invention also provides an electrolytic negative electrode comprising a catalyst layer derived from the coating liquid composition.

Here, the above-mentioned "catalyst layer derived from the coating liquid composition" refers to a catalyst layer prepared using the above liquid composition.

The electrolytic anode according to an embodiment of the present invention includes a metal base layer; And a catalyst layer formed on at least one side of the substrate layer, wherein the catalyst layer is derived from the coating liquid composition and is porous.

Further, the catalyst layer has a layered structure.

The catalyst layer may have a microporous structure and a layered structure by being derived from the above-mentioned coating liquid composition, and the specific surface area may be increased.

Therefore, the electrolytic anode according to the present invention can improve the overvoltage by including the catalyst layer.

The metal base layer may be made of a metal base, and the base metal may be titanium, tantalum, aluminum, hafnium, nickel, zirconium, molybdenum, tungsten, stainless steel or an alloy thereof. .

In addition, the metal base layer may have fine irregularities formed on its surface.

Meanwhile, the electrolytic anode according to the present invention may be manufactured by a manufacturing method described below.

1) alcohol solvent; Platinum group metal precursors; Lanthanide metal precursors; And a stabilizing agent; And

2) coating the coating liquid on at least one surface of the metal substrate, drying and then heat treating the coating liquid.

The step 1 is a step for preparing the above-described coating liquid composition for forming a catalyst layer in an electrolysis cathode, and may be performed by adding and mixing a platinum group metal precursor, a lanthanide metal precursor and a stabilizer to an alcoholic solvent. The mixing may be performed by stirring or dispersing with an ultrasonic disperser. The mixing may be performed at ambient temperature, or at a temperature of 30 ° C or higher, or at a temperature of 50 ° C to 70 ° C for 1 hour or more, or 3 hours to 10 hours.

At this time, specific materials and ratios of the alcohol solvent, the platinum group metal precursor, the lanthanide group metal precursor and the stabilizer are as defined in the coating liquid composition described above.

The step 2 is a step for preparing an electrolytic negative electrode comprising a catalyst layer derived from the coating liquid composition. The coating liquid composition may be applied on at least one surface of a metal substrate, dried, and then heat-treated.

Here, the kind of the above-mentioned metal base material is as described above.

Meanwhile, the metal substrate may be a surface treated before applying the coating liquid composition, wherein the surface treatment is performed by sandblasting the surface of the metal substrate to form fine irregularities, followed by salt treatment and acid treatment . For example, in one embodiment of the present invention, the surface of the metal substrate is sand blasted with aluminum oxide (120 mesh) under a condition of 0.4 MPa to form a concavo-convex structure, and a 3 wt% aqueous solution of NaOH After immersion, the surface treatment was performed again by immersing in 18 wt% HCl aqueous solution at room temperature for 3 minutes.

The metal substrate is not particularly limited, but may have a thickness of 50 탆 to 500 탆.

The coating is not particularly limited as long as the coating liquid composition can be applied evenly on the metal substrate. The coating can be performed by a method known in the art, for example, uniformly dispersed using a doctor blade or the like, May be accomplished through die casting, comma coating, screen printing, spray coating, electrospinning, roller coating, brushing, have.

The drying may be carried out at 50 to 400 ° C for 5 minutes to 60 minutes, and more specifically, at 50 ° C to 100 ° C for 10 minutes to 30 minutes.

In addition, the heat treatment may be performed at 400 ° C to 600 ° C for 1 hour or less, specifically 400 ° C to 500 ° C for 10 minutes to 30 minutes. When the heat treatment is carried out under the above-mentioned temperature conditions, impurities in the coating liquid composition may be easily removed and the strength of the metal substrate may not be weakened. In addition, since an excessively high temperature condition is not required, the energy consumption can be reduced and the economical efficiency can be excellent.

On the other hand, the coating, drying and heat treatment in the step 2 may be repeated three times or more and 20 times or less sequentially. That is, in one embodiment of the present invention, the coating liquid composition is coated on at least one surface of a metal substrate, dried and heat-treated, and then the coating liquid composition is applied again on the surface of the metal substrate coated with the first coating liquid composition, The heat treatment may be repeated three times or more.

Specifically, the coating, drying, and heat treatment of the step 2 may be repeatedly performed five times or more and 10 times or less sequentially.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following examples and experimental examples are provided for illustrating the present invention, and the scope of the present invention is not limited thereto.

In the following examples and comparative examples, nickel (product of Ildong Metal Company, thickness 200 m, Ni 99% or higher purity) was used as the metal base, and ruthenium chloride hydrate RuCl ₃ .nH ₂ O of Yurui was used as the platinum group metal precursor. The lanthanide metal precursor was cesium nitrate hexahydrate (Ce (NO ₃ ) ₃ .6H ₂ O) from Simga-Aldrich, the stabilizing agent was sodium dodecyl sulfate (SDS) Were purchased from Aldrich.

The ruthenium chloride hydrate was dried in a vacuum oven at 70 캜 for 20 hours to remove all of the crystal water, and was used as a precursor of ruthenium chloride.

Example 1

The surface of the nickel was sandblasted with aluminum oxide (120 mesh) at 0.4 MPa to form a concavo-convex structure, immersed in a 32 wt% NaOH aqueous solution at 90 캜 for 3 minutes, % HCl for 3 minutes to prepare a nickel substrate.

500 mg of ruthenium chloride precursor and 174 mg of cerium nitrate hexahydrate and sodium dodecyl sulfate were added to 5 ml of ethanol and dispersed with an ultrasonic disperser at 50 캜 for 3 hours to prepare a coating liquid composition. At this time, the sodium dodecyl sulfate was added in an amount of 0.25 mol based on 1 mol of the metal precursor including the ruthenium chloride precursor and the cerium nitrate hexahydrate.

The prepared coating liquid composition was coated on the surface of the nickel substrate and dried in a convection drying oven at 70 캜 for 10 minutes and then heat treated in an electric heating furnace at 400 캜 for 10 minutes. At this time, application, drying and heat treatment of the coating liquid composition were repeated 9 times, and the last 10 times heat treatment was performed at 400 ° C for 1 hour to prepare an electrolytic anode.

Example 2

An electrolytic anode was prepared in the same manner as in Example 1, except that sodium dodecyl sulfate was added in an amount of 0.0625 mol based on 1 mol of a metal precursor including a ruthenium chloride precursor and cerium nitrate hexahydrate.

Comparative Example 1

An electrolytic anode was prepared in the same manner as in Example 1, except that sodium dodecyl sulfate was not added in the preparation of the coating liquid composition.

Comparative Example 2

An attempt was made to prepare an electrolytic anode in the same manner as in Example 1, except that sodium dodecyl sulfate was added at 0.5 mol based on 1 mol of the metal precursor including the ruthenium chloride precursor and cerium nitrate hexahydrate in the preparation of the coating liquid composition, The dodecyl sulfate was not completely dissolved in the coating liquid composition and the precipitate was not formed to form the catalyst layer.

Comparative Example 3

An electrolytic anode was prepared in the same manner as in Example 1, except that sodium dodecyl sulfate was added in 1/32 mol relative to 1 mol of the metal precursor including the ruthenium chloride precursor and cerium nitrate hexahydrate in the preparation of the coating liquid composition.

Experimental Example 1

In order to compare and analyze the surface shapes of the catalyst layers of the cathodes prepared in Examples and Comparative Examples, the surface of the catalyst layer of each cathode was measured by a scanning electron microscope (SEM). The results are shown in FIG.

As shown in FIG. 1, on the surfaces of the cathode catalyst layers of Examples 1 and 2 according to one embodiment of the present invention, microcavities and a layered structure were observed, while on the surfaces of the cathode catalyst layers of Comparative Examples 1 and 3, No pore or layered structure was observed and the surface was smooth. This is because the coating liquid composition according to an embodiment of the present invention can form a catalyst layer having a porous and layered structure shape by containing a stabilizer at a certain ratio, thereby showing that the specific surface area of the catalyst layer can be increased.

Experimental Example 2

In order to compare the performance of the cathodes prepared in Examples and Comparative Examples, the voltage measurement of each cathode in the chlor-alkali electrolysis using half cells was carried out. .

A 32 wt% NaOH aqueous solution was used as the electrolyte, Pt wire was used as the counter electrode, and SCE (Saturated Calomel electrode) was used as the reference electrode. The counter electrode, the reference electrode, and each of the cathodes of Examples and Comparative Examples were immersed in the electrolytic solution and treated at a current density of 3 A / cm ² for 1 hour.

Thereafter, the voltage of the cathode was measured at a current density of -0.44 A / cm ² and -0.62 A / cm ² through Linear Sweep Voltammetry, and the results are shown in Table 1 below.

division Cathode voltage (V vs. SCE) -0.44 A / cm ² -0.62 A / cm ² Example One -1.058 -1.094 2 -1.068 -1.102 Comparative Example One -1.081 -1.119 2 N / A N / A 3 -1.184 -1.253

In Table 2, N / A indicates that the measurement was impossible. In Comparative Example 2, as described above, precipitation occurred in the coating liquid composition and a catalyst layer could not be formed. Thus, it was impossible to produce a negative electrode. I can not.

As shown in Table 1, it was confirmed that the cathodes of Examples 1 and 2 according to the embodiment of the present invention greatly reduced the overvoltage of the cathodes of Comparative Examples 1 and 3.

Claims (7)

Alcohol solvents; Platinum group metal precursors; Lanthanide metal precursors; And one species selected from sodium dodecyl sulfate, sodium lauryl sulfate, rhodium lauryl ether sulfate, sodium dodecylbenzenesulfonate, trioctylamine, oleylamine, tributylamine, cetyltrimethylammonium bromide and polyvinylpyrrolidone Or more stabilizer,
Wherein the stabilizer is contained in an amount of 0.0625 mol to 0.25 mol based on 1 mol of the metal precursor including the platinum group metal precursor and the lanthanide metal precursor.
The method according to claim 1,
Wherein the lanthanide metal precursor has a molar ratio of 0.1428 to 0.26 mole based on 1 mole of the platinum group metal precursor.
The method according to claim 1,
Wherein the platinum group metal is at least one selected from the group consisting of ruthenium, rhodium, platinum, iridium, and rhenium.
The method according to claim 1,
Wherein the lanthanide metal is at least one selected from the group consisting of lanthanum, cerium, praseodymium, neodymium and promethium.
A metal base layer; And
And a catalyst layer formed on at least one surface of the substrate layer,
The catalyst layer is derived from the coating liquid composition according to claim 1,
Wherein the catalyst layer is porous.
The method of claim 5,
Wherein the catalyst layer has a layered structure.
The method of claim 5,
Wherein the metal substrate is titanium, tantalum, aluminum, hafnium, nickel, zirconium, molybdenum, tungsten, stainless steel or an alloy thereof.

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