阅读说明：本技术 电解用电极 (Electrode for electrolysis ) 是由 金缘伊 严熙骏 金明勋 李东哲 于 2020-09-23 设计创作，主要内容包括：本发明涉及一种电解用电极,该电解用电极具有包含钌氧化物、铂系元素氧化物和锰氧化物的涂层,并且本发明的电解用电极的特征在于,表现出优异的耐久性和改善的过电压。(The present invention relates to an electrode for electrolysis having a coating layer containing ruthenium oxide, platinum group element oxide, and manganese oxide, and is characterized by exhibiting excellent durability and improved overvoltage.)

1. An electrode for electrolysis, comprising:

a metal base layer; and

a coating comprising ruthenium oxide, platinum group element oxide and manganese oxide,

wherein the coating layer is formed on at least one surface of the metal base layer.

2. The electrode for electrolysis according to claim 1, wherein the coating layer contains ruthenium element and manganese element at a weight ratio of 100:5 to 100: 30.

3. The electrode for electrolysis according to claim 1, wherein the coating layer contains ruthenium element and platinum group element at a weight ratio of 100:40 to 100: 70.

4. The electrolytic electrode of claim 1, wherein the coating further comprises cerium oxide.

5. The electrode for electrolysis according to claim 4, wherein the coating layer contains the ruthenium element and the cerium element at a weight ratio of 100:40 to 100: 90.

6. A method for manufacturing an electrode for electrolysis, comprising:

applying a coating composition to at least one surface of a metal substrate; and

drying and heat-treating the metal substrate coated with the coating composition to coat the metal substrate,

wherein the coating composition comprises a ruthenium precursor, a platinum group element precursor, and a manganese precursor.

7. The production method according to claim 6, wherein the coating composition further comprises a cerium precursor.

8. The manufacturing method according to claim 6, wherein the ruthenium precursor is selected from ruthenium hexafluoride (RuF)₆) Ruthenium (III) chloride (RuCl)₃) Ruthenium (III) chloride hydrate (RuCl)₃·xH₂O), ruthenium (III) bromide (RuBr)₃) Ruthenium (III) bromide hydrate (RuBr)₃·xH₂O), ruthenium iodide (RuI)₃) And ruthenium acetate.

9. The production method according to claim 6, wherein the manganese precursor is at least one selected from the group consisting of manganese chloride, manganese chloride hydrate, manganese (II) nitrate tetrahydrate, and manganese (II) nitrate.

10. The production method according to claim 6, wherein the platinoid element precursor is selected from chloroplatinic acid hexahydrate (H)₂PtCl₆·6H₂O), diammine dinitroplatinum (Pt (NH)₃)₂(NO)₂) Platinum (IV) chloride (PtCl)₄) Platinum (II) chloride (PtCl)₂) Potassium tetrachloroplatinate (K)₂PtCl₄) And potassium hexachloroplatinate (K)₂PtCl₆) At least one of (1).

11. The production method according to claim 7, wherein the cerium precursor is selected from cerium (III) nitrate hexahydrate (Ce (NO)₃)₃·6H₂O), cerium (IV) sulfate tetrahydrate (Ce (SO)₄)₂·4H₂O) and cerium (III) chloride heptahydrate (CeCl)₃·7H₂O).

12. The production method according to claim 6, wherein the coating composition further comprises at least one amine additive selected from the group consisting of melamine, ammonia, urea, 1-propylamine, 1-butylamine, 1-pentylamine, 1-heptylamine, 1-octylamine, 1-nonylamine and 1-dodecylamine.

13. The production method according to claim 12, wherein a molar ratio of the ruthenium element of the ruthenium precursor to the amine-based additive contained in the coating composition is 100:10 to 100: 50.

Technical Field

Cross Reference to Related Applications

The present application claims the benefit of korean patent application No.10-2019-0119113, filed on 26.9.2019, the disclosure of which is incorporated in its entirety by reference into the present specification.

The present invention relates to an electrolysis electrode capable of improving overvoltage, and a method for manufacturing the electrolysis electrode.

Background

Techniques for electrolyzing low cost brines such as seawater to produce hydroxides, hydrogen, and chlorine are well known. This electrolytic process is also commonly referred to as the chloralkali process and can be considered a process that has proven the performance and reliability of the technology through commercial operations for decades.

For electrolysis of brine, the ion exchange membrane method is most widely used in recent years, in which an ion exchange membrane is installed inside an electrolytic cell such that the electrolytic cell is divided into a cation chamber and an anion chamber, and brine is used as an electrolytic solution to obtain chlorine gas from an anode and hydrogen and caustic soda from a cathode.

Meanwhile, the electrolysis process of the brine proceeds through the reaction as described in the following electrochemical reaction scheme:

and (3) anode reaction: 2Cl^-→Cl₂+2e^-(E⁰＝+1.36V)

And (3) cathode reaction: 2H₂O+2e^-→2OH^-+H₂(E⁰＝-0.83V)

And (3) overall reaction: 2Cl^-+2H₂O→2OH^-+Cl₂+H₂(E⁰＝-2.19V)

In the electrolysis of brine, the theoretical voltage required for the electrolysis of brine as well as 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 the cathode should be considered for the electrolysis voltage, and among these, the overvoltage due to the electrode has served as an important variable.

Therefore, research into a method that can reduce overvoltage of an electrode has been conducted, and for example, a noble metal-based electrode called a Dimensionally Stable Anode (DSA) has been developed and used as an anode, while for a cathode, development of an excellent material having durability and low overvoltage is required.

Stainless steel or nickel has been mainly used as a cathode, and in order to reduce overvoltage, a method of coating the surface of stainless steel or nickel with nickel oxide, an alloy of nickel and tin, a combination of activated carbon and an oxide, ruthenium oxide, platinum, or the like and using it has been recently studied.

In addition, in order to adjust the composition of the active material to improve the activity of the cathode, a method of adjusting the composition using a platinum group element such as ruthenium and a lanthanide group element such as cerium has also been studied. However, there is a limit in that an overvoltage phenomenon occurs and deterioration occurs due to a reverse current.

Documents of the prior art

(patent document 1) JP 2003-2977967A

Disclosure of Invention

Technical problem

An aspect of the present invention provides an electrode for electrolysis capable of reducing overvoltage by improving electrical characteristics of a surface coating of the electrode.

Technical scheme

According to an aspect of the present invention, there is provided an electrode for electrolysis, comprising: a metal base layer; and a coating layer comprising ruthenium oxide, platinum group element oxide, and manganese oxide, wherein the coating layer is formed on at least one surface of the metal base layer.

According to another aspect of the present invention, there is also provided a method of manufacturing an electrode for electrolysis, the method comprising: applying a coating composition to at least one surface of a metal substrate; and drying and heat-treating the metal substrate coated with the coating composition to coat the metal substrate, wherein the coating composition comprises a ruthenium precursor, a platinum group element precursor, and a manganese precursor.

Advantageous effects

The electrode for electrolysis of the present invention exhibits excellent overvoltage and also has excellent durability due to interaction of tin oxide contained in the coating layer with ruthenium oxide and platinum group element oxide contained together to improve electrical conductivity.

Detailed Description

Hereinafter, the present invention will be described in more detail.

It should be understood that the words or terms used in the specification and claims should not be construed as meanings defined in common dictionaries, and it should be understood that the words or terms should be interpreted as having meanings consistent with their meanings in the context of the relevant art and the technical idea of the present invention on the basis of the principle that the inventor can appropriately define the meanings of the words or terms to best explain the invention.

Electrode for electrolysis

The present invention provides an electrode for electrolysis, comprising: a metal base layer; and a coating layer comprising ruthenium oxide, platinum group element oxide, and manganese oxide, wherein the coating layer is formed on at least one surface of the metal base layer.

The metal substrate may be nickel, titanium, tantalum, aluminum, hafnium, zirconium, molybdenum, tungsten, stainless steel, or an alloy thereof, wherein preferably, nickel. In the electrode for electrolysis of the present invention, when these kinds of metal substrates described above are used, excellent durability and mechanical strength can be provided to the electrode.

In the electrode for electrolysis of the present invention, the coating layer contains ruthenium oxide. The ruthenium oxide is used to provide ruthenium element as an active material to the coating layer, and when the ruthenium oxide is used in the coating layer of the electrode for electrolysis, an overvoltage phenomenon is improved, and the change of the performance of the electrode with time is small, and a separate subsequent activation process can be minimized. The ruthenium oxide includes all kinds of oxide forms in which ruthenium element is bonded to an oxygen atom, and specifically, may be a dioxide or a tetraoxide.

In the electrode for electrolysis of the present invention, the coating layer contains an oxide of a platinum group element. The platinum group element oxide means an oxide of an element other than the above ruthenium in the platinum group element, and specifically, may be rhodium oxide, palladium oxide, osmium oxide, iridium oxide, or platinum oxide. The platinum group element provided by the platinum group element oxide may act as an active material like the ruthenium element, and when the platinum group element oxide and the ruthenium oxide are included together in the coating layer, more excellent effects may be exhibited in terms of durability and overvoltage of the electrode. The platinum group element oxide includes all kinds of oxide forms in which a platinum group element is bonded to an oxygen atom, and specifically, may be a dioxide or a tetraoxide, and is preferably a platinum oxide or an iridium oxide.

In the electrolytic electrode of the present invention, the coating layer contains a manganese oxide. The manganese oxide interacts with the ruthenium oxide and platinum group element oxide as described above to improve the conductivity of the coating, thereby improving the final overvoltage of the electrode for electrolysis. The manganese oxide includes all kinds of oxide forms in which manganese element is bonded to oxygen atom, and specifically, may be manganese (II, III) oxide (Mn)₃O₄) Or manganese (III) oxide (Mn)₂O₃)。

The weight ratio of the ruthenium element to the platinum group element contained in the coating layer may be 100:40 to 100:70, and preferably, 100:50 to 100: 65. When the weight ratio of the ruthenium element to the platinum group element contained in the coating layer is within the above range, it is preferable in terms of improvement of durability and overvoltage, and when the content of the platinum group element is less than the range, the durability and overvoltage are deteriorated, and when the content is more than the range, it is disadvantageous in view of economic feasibility.

The weight ratio of the ruthenium element to the manganese element contained in the coating layer may be 100:5 to 100:30, and preferably, 100:10 to 100: 25. When the weight ratio of the ruthenium element to the manganese element contained in the coating layer is within the above range, the effect of improving the electrical conductivity of the coating layer can be maximized.

In the electrolysis electrode of the present invention, the coating layer may further contain cerium oxide, and the cerium oxide is used to supply a lanthanoid element to the catalyst layer of the electrolysis electrode. The cerium element provided by the cerium oxide may improve the durability of the electrode for electrolysis, thereby minimizing the loss of the ruthenium element as an active material in the catalyst layer of the electrode for electrolysis during activation or electrolysis.

In more detail, when the electrode for electrolysis is activated or electrolyzed, the particles containing the ruthenium element in the catalyst layer become a metal element or are partially hydrated to be reduced to an active material without changing the structure thereof. Further, the particles containing a lanthanide element in the catalyst layer may change the structure into a needle shape to serve as a protective material to prevent the particles containing a ruthenium element in the catalyst layer from being physically separated, so that the durability of the electrode for electrolysis is improved, thereby preventing the loss of the ruthenium element in the catalyst layer. The cerium oxide includes all kinds of oxide forms in which cerium is bonded to an oxygen atom, and specifically, may be cerium (II) oxide, cerium (III) oxide, or cerium (IV) oxide.

The weight ratio of the ruthenium element to the cerium element contained in the coating layer may be 100:40 to 100:90, and preferably, 100:45 to 100: 85. When the weight ratio of the ruthenium element to the cerium element contained in the coating layer is within the above range, the balance between the durability and the electrical conductivity of the electrode for electrolysis may be excellent.

Method for manufacturing electrode for electrolysis

The present invention provides a method for manufacturing an electrode for electrolysis, the method comprising: applying a coating composition to at least one surface of a metal substrate; and drying and heat-treating the metal substrate coated with the coating composition to coat the metal substrate, wherein the coating composition comprises a ruthenium precursor, a platinum group element precursor, and a manganese precursor.

In the method of manufacturing an electrolysis electrode of the present invention, the metal base may be the same as that of the electrolysis electrode described above.

In the method for manufacturing an electrolytic electrode of the present invention, the coating composition may include a ruthenium precursor, a platinum group element precursor, and a manganese precursor. After coating, the ruthenium precursor, platinum group element precursor, and manganese precursor are oxidized in a heat treatment to be converted into oxides.

Any compound may be used as the ruthenium precursor without particular limitationAre not limited as long as they can form ruthenium oxide, and may be, for example, a hydrate, hydroxide, halide or oxide of ruthenium, specifically, selected from ruthenium hexafluoride (RuF)₆) Ruthenium (III) chloride (RuCl)₃) Ruthenium (III) chloride hydrate (RuCl)₃·xH₂O), ruthenium (III) bromide (RuBr)₃) Ruthenium (III) bromide hydrate (RuBr)₃·xH₂O), ruthenium iodide (RuI)₃) And ruthenium acetate. When the ruthenium precursors listed above are used, ruthenium oxide can be easily formed.

Any compound may be used as the platinum group element precursor without particular limitation as long as they can form a platinum group element oxide, and may be, for example, a hydrate, a hydroxide, a halide or an oxide of a platinum group element, specifically, may be selected from chloroplatinic acid hexahydrate (H)₂PtCl₆·6H₂O), diammine dinitroplatinum (Pt (NH)₃)₂(NO)₂) Platinum (IV) chloride (PtCl)₄) Platinum (II) chloride (PtCl)₂) Potassium tetrachloroplatinate (K)₂PtCl₄) Potassium hexachloroplatinate (K)₂PtCl₆) Or iridium precursors such as iridium chloride or iridium chloride hydrate (IrCl)₃·xH₂O) at least one platinum group element precursor. When the platinum group element precursors listed above are used, platinum group element oxides can be easily formed.

Any compound may be used as the manganese precursor without particular limitation so long as they can form a manganese oxide, and may be, for example, a hydrate, a hydroxide, a halide or an oxide of the manganese element, and specifically, may be a manganese precursor such as manganese chloride, manganese chloride hydrate, manganese (II) nitrate tetrahydrate, or manganese (II) nitrate. When the above-listed manganese precursors are used, manganese oxides can be easily formed.

The coating composition may further comprise a cerium precursor for forming cerium oxide in the coating. Any compounds may be used as the cerium precursor without particular limitation so long as they can form cerium oxide, and may be, for example,a hydrate, hydroxide, halide or oxide of the element cerium, in particular, it may be selected from cerium (III) nitrate hexahydrate (Ce (NO)₃)₃·6H₂O), cerium (IV) sulfate tetrahydrate (Ce (SO)₄)₂·4H₂O) and cerium (III) chloride heptahydrate (CeCl)₃·7H₂O) at least one cerium precursor. When the above-listed cerium precursors are used, cerium oxide can be easily formed.

In the method for manufacturing an electrolytic electrode of the present invention, the coating composition may further include an amine-based additive to impart strong adhesion between the coating layer and the metal substrate. In particular, the amine-based additive can improve the adhesion between the ruthenium element, the platinum group element, and the manganese element contained in the coating layer, and adjust the oxidation state of the particles containing the ruthenium element to manufacture an electrode having a more suitable form for reaction.

The amine-based additive used in the present invention has an amino group and has high solubility in water, and is particularly suitable for forming a coating layer. The amine-based additive that can be used in the present invention includes melamine, ammonia, urea, 1-propylamine, 1-butylamine, 1-pentylamine, 1-heptylamine, 1-octylamine, 1-nonylamine, 1-dodecylamine, etc., and at least one selected from them can be used.

In the electrode for electrolysis of the present invention, the ruthenium element and the amine additive of the coating layer may be contained in a molar ratio of 100:10 to 100:50, preferably 100:25 to 100: 35. When the content of the amine additive is less than the above range, the effect of improving the adhesive force by the additive is insignificant, and when the content of the amine additive is greater than the above range, precipitation may occur in the coating solution, and thus, the uniformity of the coating layer may be deteriorated and the function of the ruthenium oxide may be prevented.

In the method for producing an electrolytic electrode of the present invention, an alcohol solvent can be used as a solvent for the coating composition. When an alcohol solvent is used, the above components are easily dissolved, and the adhesion of each component can be maintained even when a coating layer is formed after the coating composition is applied. Preferably, at least one of isopropanol and butoxyethanol may be used as the solvent, and more preferably, a mixture of isopropanol and butoxyethanol may be used. When isopropyl alcohol and butoxyethanol are mixed and used, uniform coating can be performed compared to the use alone.

The manufacturing method of the present invention may include pre-treating the metal substrate before coating.

In the pretreatment, the metal substrate may be chemically etched, sandblasted, or thermally sprayed to form irregularities on the surface of the metal substrate.

The pretreatment may be performed by sandblasting the surface of the metal substrate to form fine irregularities thereon and treatment with an alkali or an acid. For example, pretreatment may be performed such that the surface of the metal substrate may be sandblasted with alumina to form irregularities, dipped in an aqueous sulfuric acid solution, washed and dried to form fine irregularities on the surface of the metal substrate.

The coating is not particularly limited as long as the catalyst composition can be uniformly coated on the metal substrate, and the coating may be performed in a method known in the art.

The coating may be performed by any one method selected from the group consisting of doctor blade, die casting, comma coating, screen printing, spray coating, electrospinning, roll coating, and brush coating.

The drying may be performed at 50 to 300 ℃ for 5 to 60 minutes, and preferably at 50 to 200 ℃ for 5 to 20 minutes.

If the above conditions are satisfied, the solvent can be sufficiently removed while energy consumption can be minimized.

The heat treatment may be performed at 400 to 600 ℃ for 1 hour or less, and preferably at 450 to 550 ℃ for 5 to 30 minutes.

If the above conditions are satisfied, impurities in the catalyst layer can be easily removed without affecting the strength of the metal base.

Meanwhile, the coating may be performed by sequentially repeating the coating, drying, and heat treatment, so that it is based on the unit area (m) of the metal substrate²) Of at least 10 g. Namely, it isThe manufacturing method according to another embodiment of the present invention may be performed by repeating coating on at least one surface of a metal substrate, wherein the catalyst composition is coated, dried and heat-treated, and then the catalyst composition is coated again, dried and heat-treated on one surface of the metal substrate coated with the first catalyst composition.

Hereinafter, examples and experimental examples will be described in more detail in order to specifically describe the present invention, but the present invention is not limited to these examples and experimental examples. Embodiments according to the present invention may be modified in various other types, and the scope of the present invention should not be construed as being limited to the embodiments described below. Rather, embodiments of the invention are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Material

In the examples, a nickel mesh substrate (Ni purity of 99% or more, 200 μm) manufactured by Il-dong Wire cloud Co. was used as a metal substrate, and ruthenium (III) chloride hydrate (RuCl) was used₃·nH₂O) as ruthenium precursor, platinum (IV) chloride as platinum group element precursor, and cerium (III) nitrate hexahydrate (Ce (NO)₃)₃·6H₂O) As cerium precursor, manganese (II) chloride tetrahydrate (MnCl) was used₂·4H₂O) as a manganese precursor. Urea is used as amine additive.

In addition, a mixture of 2.375mL of isopropanol and 2.375mL of 2-butoxyethanol was used as a solvent for the coating composition.

Pretreatment of metal substrates

Before forming a coating on a metal substrate, the surface of the substrate was sandblasted with alumina (white alumina, F120) under 0.4MPa, and then added to 5M of H which had been heated to 80 ℃₂SO₄Aqueous solution, and treated for 3 minutes, followed by washing the substrate with distilled water to complete the pretreatment.

Example 1

In the mixed solvent of the above materials, 2.41mmol of ruthenium (III) chloride hydrate, 0.1928mmol of platinum (IV) chloride and 0.482mmol of manganese (II) chloride tetrahydrate were sufficiently dissolved for 1 hour, and 0.045g of urea was added thereto and mixed to prepare a coating composition. The coating composition was coated on the above pretreated metal substrate using a brush, and the coated metal substrate was put into a convection drying oven and dried at 180 ℃ for 10 minutes. Then, the metal substrate was put into an electric heating furnace at 500 ℃ for further heat treatment for 10 minutes, the process of coating, drying and heat treatment was repeated 9 more times, and then, the metal substrate was subjected to final heat treatment at 500 ℃ for 1 hour to manufacture an electrode for electrolysis.

Example 2

An electrode for electrolysis was produced by the same method as in example 1 above, except that 0.241mmol of cerium (III) nitrate hexahydrate and 0.241mmol of manganese (II) chloride tetrahydrate were further added to the coating composition.

Comparative example 1

An electrode for electrolysis was produced by the same method as in example 1 above, except that platinum (IV) chloride was not added to the coating composition.

Comparative example 2

An electrode for electrolysis was produced by the same method as in example 2 above, except that platinum (IV) chloride was not added to the coating composition.

Comparative example 3

An electrode for electrolysis was produced by the same method as in example 2 above, except that manganese (II) chloride tetrahydrate was not added, and 0.482mmol of cerium (III) nitrate hexahydrate was added.

Comparative example 4

An electrode for electrolysis was produced by the same method as in comparative example 1 above, except that platinum (IV) chloride was not added to the coating composition.

The molar ratios between the respective precursors in the coating compositions used in the above examples 1 and 2 and comparative examples 1 to 4 are shown in the following table 1.

[ Table 1]

	Example 1	Example 2	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
							Ruthenium (II)	2.41	2.41	2.41	2.41	2.41	2.41
Manganese oxide	0.482	0.241	0.482	0.241	-	-
							Platinum (II)	0.1928	0.1928	-	-	0.1928	-
Cerium (Ce)	-	0.241	-	0.241	0.482	0.482

Experimental example 1 confirmation of the Performance of the produced electrode for electrolysis

In order to confirm the performance of the electrodes manufactured in the above examples 1 and 2 and comparative examples 1 to 4, a cathode voltage measurement test was performed by using a half cell in chlor-alkali electrolysis. As electrolyte solution, a 32% NaOH aqueous solution was used, Pt wire was used as counter electrode, and Hg/HgO electrode was used as reference electrode. The fabricated electrode was immersed in an electrolyte solution and then immersed at-0.62A/cm²Was activated for 1 hour under the condition of constant current density, and then the performances of the respective electrodes were compared using the potential value at 1 hour. The results are shown in table 2 below.

[ Table 2]

From the above results, it was confirmed that the effect of improving overvoltage was exhibited when the manganese oxide was further added to the coating layer.

Experimental example 2 Mass Spectrometry analysis of coating of electrode

The weight ratio (%) of each metal component of the surface coating layer of the electrodes manufactured in the above examples and comparative examples was analyzed by X-ray fluorescence spectroscopy (XRF). The results are shown in table 3 below.

[ Table 3]

Categories	Example 1	Example 2	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
							Ru	5.76	5.49	5.65	5.78	5.49	5.63
Mn	1.29	0.72	1.32	1.64	-	-
							Pt	3.22	3.26	-	-	3.17	-
Ce	-	2.35	-	2.67	4.44	4.36

From the results of table 3 above, it was confirmed that even if manganese oxide was contained in the coating layer, the composition of other metal components was not affected and oxide could be formed.