Hydroxide catalyst body, water electrolysis electrode and water electrolysis system comprising same, and manufacturing method therefor

Abstract

The present invention provides a hydroxide catalyst body, an electrode and a water electrolysis system comprising same, and a manufacturing method therefor, wherein the hydroxide catalyst body is simple to manufacture, can exhibit reduced contact resistance, and can prevent the separation thereof The method for manufacturing a hydroxide catalyst body according to an embodiment of the present invention comprises the steps of: providing a metal-containing support having a nickel surface layer; forming a metal precursor layer on the surface of the metal-containing support by reacting the metal-containing support with an acidic gas; and inducing a reaction between the metal precursor layer and a hydroxide solution to form a hydroxide structure.

Description

Hydroxide catalyst, electrolysis electrode and electrolysis system including the same, and method for manufacturing the same

[0001] The technical idea of ​​the present invention relates to a water electrolysis catalyst, and more particularly, to a hydroxide catalyst, a water electrolysis electrode and water electrolysis system including the same, and a method for manufacturing the same.

[0002] This invention was conducted as a result of research supported by the Ministry of Trade, Industry and Energy's 'Material Components Technology Development' [Project Name: Development of Technology for Manufacturing and Component Manufacturing of Rare Metals (Ni Co Pt) with Reduced Precious Metals, Project Number: 20020229, Project Unique Number: 1415186194, Project Management (Specialized) Institution Name: Korea Institute of Industrial Technology Planning and Evaluation].

[0003] Water electrolysis systems are devices for generating renewable energy, and are a technology field attracting attention for their potential to reduce energy conversion, fossil fuel use, and, consequently, environmental pollution. Conventional oxygen evolution reaction (OER) catalysts used in water electrolysis systems are typically manufactured using powder coating, which coats a metal electrode with catalyst powder, or a selective pickling method, which creates pores by adding alloying elements to the metal electrode and then selectively removing them with acid. However, powder coating can generate contact resistance between the catalyst powder and the electrode, and the catalyst powder may fall off during use. Furthermore, selective pickling requires casting the metal electrode with alloying elements, and post-pickling treatment can increase the cost.

[0004] Furthermore, conventional hydroxide-based oxygen-generating electrode catalysts are either grown directly on the electrode or synthesized separately, then coated with catalyst ink. While the direct growth method offers superior properties, it suffers from the complex synthesis process and difficulty in scale-up. The coating method, while advantageous for mass production, suffers from drawbacks such as the need for multiple process steps, resulting in deteriorated properties due to the binder used in the ink.

[0005] Therefore, a water electrolysis electrode, such as an oxygen evolution electrode, which can be formed in an effective and easy manner and has excellent durability is required.

[0006] The technical problem to be achieved by the technical idea of ​​the present invention is to provide a hydroxide catalyst body having a simple manufacturing method, capable of reducing contact resistance and preventing the catalyst body from falling off, a water electrolysis electrode and water electrolysis system including the same, and a manufacturing method thereof.

[0007] However, these tasks are exemplary and the technical idea of ​​the present invention is not limited thereto.

[0008] According to one embodiment of the present invention, a method for producing a hydroxide catalyst may include the steps of: providing a metal-containing support; reacting the metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support; and forming a hydroxide structure by inducing a reaction between the metal precursor layer and a hydroxide solution.

[0009] According to one embodiment of the present invention, the step of forming the metal precursor layer can be performed at a temperature range in which the free energy of the metal precursor constituting the metal precursor layer is lower than that of the metal or metal oxide constituting the metal-containing support.

[0010] According to one embodiment of the present invention, the step of forming the metal precursor layer comprises: 20 o C to 1000 o It can be performed for 1 minute to 48 hours at a temperature range of C.

[0011] According to one embodiment of the present invention, the step of forming the hydroxide structure comprises: after injecting the hydroxide solution into the metal precursor layer, 0 o C to 100 o It can be performed by maintaining it for 1 second to 24 hours at a temperature in the range of C.

[0012] According to one embodiment of the present invention, the metal-containing support may include at least one of a nickel-containing metal and a nickel-containing metal-ceramic composite.

[0013] According to one embodiment of the present invention, the metal-containing support may include at least one of pure nickel, a nickel alloy, an Inconel alloy, an Incoloy alloy, and nickel-containing stainless steel.

[0014] According to one embodiment of the present invention, the acidic gas may include at least one of hydrogen chloride gas, nitric acid gas, sulfuric acid gas, chlorine gas, ammonia gas, hydrogen nitride gas, hydrogen sulfide gas, hydrogen fluoride gas, perchloric acid gas, acetic acid gas, acrylic acid gas, and acetylacetonate gas.

[0015] According to one embodiment of the present invention, the partial pressure of the acidic gas may range from 1% to 50%.

[0016] According to one embodiment of the present invention, the metal precursor layer may include at least one of a metal chloride, a metal nitrate, a metal sulfate, a metal sulfide, a metal fluoride, a metal perchlorate, a metal acetate, a metal acrylic acid, and a metal acetylacetonate.

[0017] According to one embodiment of the present invention, the metal precursor layer may include at least one of nickel chloride, nickel nitrate, nickel sulfate, nickel sulfide, nickel fluoride, nickel perchlorate, nickel acetate, nickel acrylate, and nickel acetylacetonate.

[0018] According to one embodiment of the present invention, the hydroxide solution may include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, strontium hydroxide, ammonium hydroxide, or a mixture thereof.

[0019] According to one embodiment of the present invention, the step of washing and drying the hydroxide structure may be further included.

[0020] According to one embodiment of the present invention, the step of providing a metal-containing support may be performed by performing the step of providing the metal-containing support having a nickel surface layer.

[0021] According to one embodiment of the present invention, the step of providing the metal-containing support having the nickel surface layer may include the step of forming a nickel surface layer on the surface of the metal-containing support; and the step of homogenizing the nickel surface layer with heat treatment.

[0022] According to one embodiment of the present invention, the step of forming the nickel surface layer can be performed by forming the nickel surface layer on the surface of the metal-containing support using electrolytic plating, electroless plating, physical vapor deposition, chemical vapor deposition, or galvanic substitution.

[0023] According to one embodiment of the present invention, the step of homogenizing the nickel surface layer is performed at 200° C. under a reducing atmosphere. o C to 1200 o It can be performed for 10 minutes to 10 hours at temperatures in the C range.

[0024] According to one embodiment of the present invention, the metal-containing support may include cast iron, steel, stainless steel, copper, aluminum, or an alloy thereof.

[0025] According to one embodiment of the present invention, an electrode includes an electrode support; and a hydroxide catalyst body positioned on the electrode support, wherein the hydroxide catalyst body may include a hydroxide structure formed by reacting a metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support, and inducing a reaction between the metal precursor layer and a hydroxide solution.

[0026] According to one embodiment of the present invention, the hydroxide structure has an equivalent diameter in the range of 1 μm to 20 μm, and the hydroxide structure can exhibit an overvoltage in the range of 50 mV to 400 mV.

[0027] According to one embodiment of the present invention, a water electrolysis system includes an anode, a cathode, and an electrolyte, wherein the anode includes an electrode support; and a hydroxide catalyst body positioned on the electrode support, wherein the hydroxide catalyst body may include a hydroxide structure formed by reacting a metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support, and inducing a reaction between the metal precursor layer and a hydroxide solution.

[0028] According to the technical concept of the present invention, the hydroxide catalyst can be manufactured in a simple manner, has reduced contact resistance, and prevents catalyst detachment. Furthermore, it can reduce overvoltage, thereby providing an efficient water electrolysis electrode with high oxygen evolution reaction activity.

[0029] The effects of the present invention described above are illustrative, and the scope of the present invention is not limited by these effects.

[0030] Figure 1 is a flow chart explaining a method for manufacturing a hydroxide catalyst according to one embodiment of the present invention.

[0031] FIGS. 2 and 3 are graphs showing the Gibbs free energy for the reaction of nickel and iron with hydrogen chloride gas applied to a hydroxide catalyst according to one embodiment of the present invention.

[0032] Figure 4 is a flow chart explaining a method for manufacturing a hydroxide catalyst according to one embodiment of the present invention.

[0033] FIGS. 5 and 6 are schematic diagrams illustrating an electrode including a hydroxide catalyst according to one embodiment of the present invention.

[0034] Figure 7 is a schematic diagram illustrating a water electrolysis system according to one embodiment of the present invention.

[0035] FIGS. 8 to 10 are graphs showing the electrocatalytic characteristics of a hydroxide catalyst body formed using nickel foil according to one embodiment of the present invention.

[0036] Figures 11 and 12 are graphs showing the electrocatalytic characteristics of a hydroxide catalyst body formed using stainless steel 304 foil according to one embodiment of the present invention.

[0037] Figure 13 is an external photograph of a hydroxide catalyst formed using nickel foil according to one embodiment of the present invention.

[0038] FIGS. 14 and 15 are scanning electron microscope photographs showing the microstructure of a hydroxide catalyst according to an embodiment of the present invention.

[0039] Figure 16 is a graph showing the overvoltage of a hydroxide catalyst formed using various metal-containing supports according to one embodiment of the present invention.

[0040] FIG. 17 is a graph showing the overvoltage of a hydroxide catalyst formed using a metal-containing support having various nickel surface layers according to an embodiment of the present invention.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Embodiments of the present invention are provided to more completely explain the technical idea of ​​the present invention to those skilled in the art. The following embodiments may be modified in various different forms, and the scope of the technical idea of ​​the present invention is not limited to the following embodiments. Rather, these embodiments are provided to more faithfully and completely convey the technical idea of ​​the present invention to those skilled in the art. Like reference numerals throughout this specification denote like elements. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the technical idea of ​​the present invention is not limited by the relative sizes or intervals drawn in the attached drawings.

[0042] Figure 1 is a flow chart explaining a method for manufacturing a hydroxide catalyst according to one embodiment of the present invention.

[0043] Referring to FIG. 1, a method for manufacturing a hydroxide catalyst (S100) includes a step of providing a metal-containing support (S110); a step of forming a metal precursor layer on the surface of the metal-containing support by reacting the metal-containing support with an acidic gas (S120); and a step of forming a hydroxide structure by inducing a reaction between the metal precursor layer and a hydroxide solution (S130).

[0044] The above method for manufacturing a hydroxide catalyst (S100) does not use organic substances, so there is no problem of deterioration of properties, it is a relatively simple process, so it is easy to mass-produce, and it has the advantage of having less problem of wastewater generation as it is a dry process.

[0045] The step (S110) of providing the metal-containing support may be performed by loading the metal-containing support into the interior of a chamber or reactor.

[0046] The metal-containing support may include, for example, at least one of a nickel-containing metal and a nickel-containing metal-ceramic composite. The metal-containing support may include, for example, at least one of pure nickel, a nickel alloy, an Inconel alloy, an Incoloy alloy, and a nickel-containing stainless steel.

[0047] The above Inconel alloy is an alloy mainly composed of nickel, and may include, for example, Inconel 600, and may include, for example, 14 to 16 wt% of chromium, 6 to 7 wt% of iron, 2 to 3 wt% of titanium, aluminum, manganese, and silicon in a total amount of more than 0 to 1 wt%, and the remainder being nickel and unavoidable impurities.

[0048] Alternatively, the Inconel alloy may include, for example, 14 to 17 wt% chromium, 6 to 10 wt% iron, and the remainder nickel and unavoidable impurities. The Inconel alloy may further include, as additional elements or unavoidable impurities, 0.15 wt% or less of carbon (including 0 wt%), 0.5 wt% or less of silicon (including 0 wt%), 1.0 wt% or less of manganese (including 0 wt%), 0.5 wt% or less of copper (including 0 wt%), 0.015 wt% or less of phosphorus (including 0 wt%), and 0.015 wt% or less of sulfur (including 0 wt%).

[0049] The above incoloy alloy is an alloy mainly composed of nickel, and may include, for example, Incoloy 800, and may include, for example, 19 to 23 wt% of chromium, 30 to 35 wt% of nickel, and the remainder being iron and unavoidable impurities. The above incoloy alloy may further include, as additional elements or unavoidable impurities, 0.1 wt% or less of carbon (including 0 wt%), 1.0 wt% or less of silicon (including 0 wt%), 1.5 wt% or less of manganese (including 0 wt%), 0.75 wt% or less of copper (including 0 wt%), 0.15 to 0.6 wt% of titanium, 0.15 to 0.6 wt% of aluminum, and 0.015 wt% or less of sulfur (including 0 wt%).

[0050] The nickel-containing stainless steel may include, for example, SUS304 or SUS316. The nickel-containing stainless steel may include, for example, 17 to 19 wt% chromium, 7 to 9 wt% nickel, and the remainder iron. The nickel-containing stainless steel may include, for example, 17 to 19 wt% chromium, 11 to 13 wt% nickel, and the remainder iron.

[0051] The nickel-containing stainless steel may include, for example, 18 to 20 wt% chromium, 8 to 12 wt% nickel, and the remainder iron and unavoidable impurities. The incoloy alloy may further include, as additional elements or unavoidable impurities, 0.08 wt% or less of carbon (including 0 wt%), 0.75 wt% or less of silicon (including 0 wt%), 2.0 wt% or less of manganese (including 0 wt%), 0.045 wt% or less of phosphorus (including 0 wt%), and 0.03 wt% or less of sulfur (including 0 wt%).

[0052] The step (S120) of forming the metal precursor layer can be performed by injecting acidic gas into the interior of the chamber or reactor.

[0053] The step (S120) of forming the metal precursor layer may be performed at a temperature range in which the free energy of the metal precursor forming the metal precursor layer is lower than that of the metal or metal oxide forming the metal-containing support. The step (S120) of forming the metal precursor layer may be performed at, for example, 20 o C to 1000 o It can be performed for 1 minute to 48 hours at a temperature range of C.

[0054] The acidic gas may include, for example, at least one of hydrogen chloride gas, nitric acid gas, sulfuric acid gas, chlorine gas, ammonia gas, hydrogen nitride gas, hydrogen sulfide gas, hydrogen fluoride gas, perchloric acid gas, acetic acid gas, acrylic acid gas, and acetylacetonate gas.

[0055] The acidic gas may be introduced into the chamber or reactor by a carrier gas composed of an inert gas such as nitrogen gas. The partial pressure of the acidic gas may range from, for example, 1% to 50% of the total gas pressure.

[0056] The metal precursor layer may be formed on the surface or within the metal-containing support through a chemical reaction between the metal-containing support and the acidic gas. That is, the metal precursor layer may be formed through a combination of a metal cation of the metal-containing support and an anion of the acidic gas. For example, when the metal-containing support is nickel and the acidic gas is hydrogen chloride, nickel chloride (NiCl2) may be formed.

[0057] The metal precursor layer may include, for example, at least one of a metal chloride, a metal nitrate, a metal sulfate, a metal sulfide, a metal fluoride, a metal perchlorate, a metal acetate, a metal acrylic acid, and a metal acetylacetonate.

[0058] Additionally, when the metal-containing support is nickel, the metal precursor layer may include, for example, at least one of nickel chloride, nickel nitrate, nickel sulfate, nickel sulfide, nickel fluoride, nickel perchlorate, nickel acetate, nickel acrylate, and nickel acetylacetonate.

[0059] Here, when an acidic solution rather than an acidic gas is used, a metal precursor such as NiCl2 is dissolved in the acidic solution and removed without forming a metal precursor layer, making it difficult to form a hydroxide structure in a subsequent process.

[0060] The step (S130) of forming the above hydroxide structure is performed after injecting the hydroxide solution into the metal precursor layer, for example, at room temperature, for example, at 0 o C to 100 o It can be performed by maintaining it for 1 second to 24 hours at a temperature in the range of C, or it can be performed by maintaining it for 1 minute to 24 hours. In the step (S130) of forming the hydroxide structure, the metal precursor layer and the hydroxide solution can react chemically and physically to form the hydroxide structure.

[0061] The above hydroxide solution can perform the function of providing hydroxide ions and can include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, strontium hydroxide, ammonium hydroxide or mixtures thereof.

[0062] In addition, the method for manufacturing a water electrolysis electrode (S100) may further include a step (S140) of cleaning and drying the hydroxide structure. The cleaning and drying step (S140) may be performed by cleaning using a cleaning solution containing, for example, water, deionized water, alcohol, carbonate, glycol, thiol, amine, acetone, or a mixture thereof, and, for example, by maintaining the cleaning solution at a temperature ranging from 0°C to 100°C for 1 minute to 24 hours and drying the cleaning solution.

[0063] FIGS. 2 and 3 are graphs showing the Gibbs free energy for the reaction of nickel and iron with hydrogen chloride gas applied to a hydroxide catalyst according to one embodiment of the present invention.

[0064] Referring to Figure 2, the Gibbs free energy for the reaction of nickel with hydrogen chloride gas is shown. Metallic nickel (Ni) preferentially reacts to form nickel chloride below 710 K (437 °C). For reference, the above temperature corresponds to the case where the partial pressure ratio of hydrogen gas (H2) or water vapor (H2O) to hydrogen chloride gas (HCl) is 1. Nickel oxide (NiO) preferentially reacts to form nickel chloride below 990 K (717 °C). Therefore, a temperature of approximately 437 °C or lower is required to react nickel with hydrogen chloride gas to form nickel chloride.

[0065] Referring to Figure 3, the Gibbs free energy for the reaction of iron with hydrogen chloride gas is shown. Metallic iron (Fe) preferentially reacts to form iron chloride below 1700 K (1427 °C). Iron oxide (FeO) preferentially reacts to form iron chloride below 1100 K (827 °C). Other iron oxides (Fe2O3, Fe3O4) preferentially react to form iron chloride within the given temperature range. Therefore, a temperature of approximately 827 °C or lower is required to react iron with hydrogen chloride gas to form iron chloride.

[0066] By obtaining the Gibbs free energy for the reaction between a metal and an acid gas in this way, the temperature range for forming the metal precursor layer can be calculated.

[0067] Figure 4 is a flow chart explaining a method for manufacturing a hydroxide catalyst according to one embodiment of the present invention.

[0068] Referring to FIG. 4, the method for manufacturing a hydroxide catalyst (S200) includes the steps of: providing a metal-containing support having a nickel surface layer (S210); reacting the metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support (S220); and forming a hydroxide structure by inducing a reaction between the metal precursor layer and a hydroxide solution (S230).

[0069] In addition, the method for manufacturing a water electrolysis electrode (S100) may further include a step (S240) of washing and drying the hydroxide structure.

[0070] The step (S210) of providing the metal-containing support may include a step of forming a nickel surface layer on the surface of the metal-containing support.

[0071] The step of forming a nickel surface layer on the surface of the metal-containing support can be accomplished by forming the nickel surface layer using electrolytic plating, electroless plating, physical vapor deposition (PVD), chemical vapor deposition (CVD), or galvanic substitution.

[0072] In addition, the step (S210) of providing the metal-containing support may further include a step of homogenizing heat treatment of the nickel surface layer.

[0073] The step of homogenizing the nickel surface layer is performed under a reducing atmosphere such as hydrogen gas or ammonia gas at 200 o C to 1200 o It can be performed for 10 minutes to 60 hours at temperatures ranging from C, or 400 o C to 600o It can be performed for 1 to 10 hours at a temperature in the range of C. By the homogenization heat treatment, the nickel surface layer can be homogenized.

[0074] The metal-containing support may include a material on which a nickel surface layer is formed, and may include, for example, cast iron, steel, stainless steel, copper, aluminum, or an alloy thereof.

[0075] The formation of a nickel surface layer by electrolytic plating or electroless plating will be described in detail.

[0076] A metal sheet or metal foam is immersed in a solution containing a dissolved nickel salt. The metal sheet or metal foam may be, for example, an iron sheet or iron foam. The nickel salt may be, for example, nickel nitride (Ni(NO3)2). According to the following formula, nickel may be plated on the iron sheet or iron foam to form a nickel surface layer.

[0077] Ni(NO3)2(l) + Fe(s) => Ni(s) + Fe(NO3)2

[0078] The above nickel surface layer is subjected to homogenization heat treatment, and the nickel surface layer is an iron-nickel alloy (FeNi x ) can be formed. Accordingly, a metal-containing support having a nickel surface layer can be formed.

[0079] The metal-containing support is reacted with an acidic gas such as hydrogen chloride (HCl) to form a metal precursor layer on the surface of the metal-containing support. At this time, the nickel surface layer reacts with the acidic gas to form a metal precursor layer.

[0080] By inducing a reaction between the above metal precursor layer and the hydroxide solution, a hydroxide structure is formed.

[0081] By forming the nickel surface layer by electrolytic plating, electroless plating, physical vapor deposition (PVD), chemical vapor deposition (CVD), or galvanic substitution and controlling the process conditions for reacting with the acidic gas, the composition of the hydroxide structure can be controlled.

[0082] The above steps (S220), (S230), and (S240) may correspond to the above steps (S120), (S130), and (S140).

[0083] FIGS. 5 and 6 are schematic diagrams illustrating an electrode including a hydroxide catalyst according to one embodiment of the present invention.

[0084] Referring to FIG. 5, the electrode (100) may include an electrode support (110) and a hydroxide catalyst body (120) including the hydroxide structure.

[0085] For example, the electrode (100) may include a hydroxide catalyst body (120) including the hydroxide structure positioned on the surface of an electrode support (110), such as nickel. The term "on the surface" means positioned on the surface of pores positioned on the outer surface or the inner surface of the electrode support (110). That is, it may mean positioned on a surface of the electrode support (110) adjacent to air.

[0086] Referring to FIG. 6, the electrode (100a) may include an electrode support (110) and a hydroxide catalyst body (120) including the hydroxide structure. A nickel surface layer (130) may be formed on the surface of the electrode support (110).

[0087] The hydroxide structures (100, 100a) of FIGS. 5 and 6 may have, for example, a circle-equivalent diameter in the range of 1 μm to 20 μm. In addition, the hydroxide structures (100, 100a) may exhibit an overvoltage in the range of, for example, 50 mV to 400 mV, or may exhibit an overvoltage in the range of 200 mV to 350 mV. In addition, the electrode support (110, 110a) may be composed of the metal-containing support described above.

[0088] According to the technical idea of ​​the present invention, a water electrolysis system including an electrode including the above hydroxide catalyst body can be provided.

[0089] Figure 7 is a schematic diagram illustrating a water electrolysis system according to one embodiment of the present invention.

[0090] Referring to FIG. 7, the electrolysis system (200) may include an anode (210), a cathode (220), and an electrolyte (230). The electrolysis system (200) may include the anode (210) as an electrode where an oxidation reaction occurs to generate oxygen, and the hydroxide structure included in the hydroxide catalyst body may serve as an oxygen generation reaction catalyst.

[0091] Accordingly, the anode (210) may include an electrode support (211); and a hydroxide catalyst body (212) positioned on the electrode support (211). The hydroxide catalyst body (212) may include a hydroxide structure formed by reacting a metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support, and inducing a reaction between the metal precursor layer and a hydroxide solution.

[0092] The cathode (220) may include an electrode support (221); and a catalyst layer (222) including a hydrogen generation reaction catalyst positioned on the electrode support (221). The electrode support (221) and the hydrogen generation reaction catalyst may be those used in the relevant technical field. The cathode (220) may use, for example, a carbon support such as carbon cloth, porous carbon cloth, carbon paper, porous carbon paper, felt or foam made of Ni, Co, Fe, Ti, Ta, etc. or an alloy thereof as the support. The hydrogen generation reaction catalyst may include, for example, a metal such as Pt, Ru, Ni, Co, Fe, or Mn; a metal oxide of Pt, Ru, Ni, Co, Fe, or Mn; an alloy including at least one of Pt, Ru, Ni, Co, Fe, and Mn; or a metal oxide including at least one of Pt, Ru, Ni, Co, Fe, and Mn.

[0093] The electrolysis system (200) may include a basic or acidic electrolyte (230) disposed between the anode (210) and the cathode (220). The electrolyte may be a basic solution, and specifically, the electrolyte may be a basic solution having a pH of 8 to 14. When a basic solution having a pH within the above range is used as the electrolyte, the overvoltage difference between the oxygen evolution reaction and the chlorine evolution reaction is maximized by using a low-concentration alkaline electrolyte, so that the chlorine evolution reaction occurs smoothly while the chlorine evolution reaction does not proceed, thereby suppressing hydrogen evolution and preventing corrosion of components, and producing high-purity hydrogen and oxygen. However, this is exemplary, and the case where the electrolyte is an acidic solution is also included in the technical idea of ​​the present invention. In addition, the case where the electrolyte is a solid substance is also included in the technical idea of ​​the present invention.

[0094] The electrolysis system (200) may further include a porous transport layer positioned adjacent to at least one of the anode (210) and the cathode (220). The porous transport layer may correspond to a gas diffusion layer (GDL) as a passage through which oxygen gas or hydrogen gas generated by the electrolysis process at the anode (210) or the cathode (220) moves. The porous transport layer may be one used in the art, and for example, a carbon support such as carbon cloth, porous carbon cloth, carbon paper, porous carbon paper, felt or foam made of Ni, Co, Fe, Ti, Ta, etc., or an alloy thereof, may be used.

[0095] The electrolysis system (220) may further include a current collecting layer.

[0096] The electrolysis system (220) may further include a power supply means. Voltage may be applied to the electrolysis system (220) from the power supply means to perform the electrolysis process. The power supply means is not particularly limited and may be any of various batteries or power generation equipment used in the relevant technical field.

[0097] Experimental example

[0098] Below, experimental examples are described to aid understanding of the present invention. The following experimental examples are presented to aid understanding of the invention, and are not limited to the following experimental examples of the present invention.

[0099] Pure nickel foil and stainless steel 304 foil with a purity of 99.9% were used as the metal-containing support, respectively.

[0100] The above metal-containing support was loaded into a reactor, and the temperature was increased from 20°C to 400°C for 30 minutes while injecting nitrogen gas at a flow rate of 1 LPM (liter per minute).

[0101] Next, hydrogen chloride (HCl) gas was injected at 15% by volume and the remainder (85% by volume) was nitrogen gas, and the reaction was maintained for 30 minutes to 3 hours. Nitrogen gas at a flow rate of 1 LPM was injected into the outlet of the reactor. Accordingly, a metal precursor layer could be formed on the surface of the metal-containing support. Subsequently, the reaction was air-cooled from 400°C to 20°C while injecting nitrogen gas at a flow rate of 1 LPM (liter per minute).

[0102] Next, a 20 molar sodium hydroxide solution, in which 16 g of sodium hydroxide is dissolved in 20 ml of water, was added to the surface of the metal-containing support using a dropper and maintained for 30 minutes to form a hydroxide structure. That is, a reaction between the metal precursor layer and the hydroxide solution can be induced. Next, the hydroxide structure was washed using deionized water and dried at 60°C to form a hydroxide catalyst.

[0103] In the above process, nickel contained in the pure nickel foil and stainless steel 304 foil can react with the hydrogen chloride gas to form nickel chloride (NiCl2) as a metal precursor layer on the surface. In addition, the nickel chloride can react with sodium hydroxide to form a nickel hydroxide structure.

[0104] Next, the hydroxide catalyst was immersed in a 1 M KOH solution, measured at a scan rate of 1 mV / s, and an LSV polarization curve was derived, and the overvoltage was analyzed accordingly.

[0105] Additionally, cases in which no hydroxide structure was formed in nickel foil and stainless steel 304 foil were set as comparative examples.

[0106] FIGS. 8 to 10 are graphs showing the electrocatalytic characteristics of a hydroxide catalyst body formed using nickel foil according to one embodiment of the present invention.

[0107] Figure 8 is a comparative example in which no hydroxide structure was formed. Figure 9 shows a case in which the reaction with hydrogen chloride gas was performed for 30 minutes. Figure 10 shows a case in which the reaction with hydrogen chloride gas was performed for 3 hours.

[0108] Referring to FIGS. 8 to 10, when comparing the overvoltage, the comparative example was 0.382 V, the example performed for 30 minutes was 0.332 V, and the case performed for 3 hours was 0.288 V. Therefore, it can be seen that when the nickel foil is treated with an acidic gas and then a hydroxide structure is formed, the overvoltage is reduced.

[0109] Figures 11 and 12 are graphs showing the electrocatalytic characteristics of a hydroxide catalyst body formed using stainless steel 304 foil according to one embodiment of the present invention.

[0110] Figure 11 is a comparative example in which a hydroxide structure is not formed. Figure 12 is a case in which a reaction with hydrogen chloride gas is performed for 30 minutes.

[0111] Referring to FIGS. 11 and 12, when comparing the overvoltage, the comparative example was 0.376 V, and the example performed for 30 minutes was 0.290 V. It can be seen that when the stainless steel 304 foil is treated with an acid gas and a hydroxide structure is formed, the overvoltage is reduced.

[0112] Figure 13 is an external photograph of a hydroxide catalyst formed using nickel foil according to one embodiment of the present invention.

[0113] Referring to Figure 13, the comparative example maintained its metallic luster on the surface after overvoltage analysis. In the example, the metallic luster on the surface disappeared after reaction with the acidic gas, and the immersed portion after overvoltage analysis appeared black. Therefore, the black color is presumed to be hydroxide formed on the surface, and it is analyzed that the overvoltage is reduced according to the formation of hydroxide.

[0114] FIGS. 14 and 15 are scanning electron microscope photographs showing the microstructure of a hydroxide catalyst according to an embodiment of the present invention.

[0115] Referring to Figure 14, the microstructure of the surface of nickel foil after reacting with an acidic gas and the surface after overvoltage analysis are shown. The dotted line area represents hydroxide with a circle-equivalent diameter of approximately 15 μm. Therefore, it can be seen that hydroxide is easily formed on nickel foil.

[0116] Referring to Figure 15, the surface microstructure of stainless steel foil after overvoltage analysis is shown. The dotted line area represents hydroxide with a circle-equivalent diameter of approximately 8 μm. Therefore, it can be seen that hydroxide is easily formed on stainless steel foil.

[0117] Below, we analyze the experimental results for hydroxide catalysts formed using various metal-containing supports. Manufacturing conditions other than those described below are as described above.

[0118] Table 1 shows the process conditions for forming hydroxide catalysts using various metal-containing supports and the overvoltage of the formed hydroxide catalysts.

[0119] Classification Metal-containing support Hydrogen chloride gas reaction Overvoltage Experimental example 1 Nickel None 310 mV Experimental example 2 Nickel 1 hr 310 mV Experimental example 3 Nickel 3 hr 350 mV Experimental example 4 SUS 304 None 336 mV Experimental example 5 SUS 304 1 hr 289 mV Experimental example 6 SUS 304 3 hr 282 mV Experimental example 7 Inconel 600 None 334 mV Experimental example 8 Inconel 6001 hr 277 mV Experimental example 9 Inconel 6003 hr 264 mV Experimental example 10 Incoloy 800 None 325 mV Experimental example 11 Incoloy 8001 hr 253 mV Experimental example 12 Incoloy 8003 hr 267 mV

[0120] Figure 16 is a graph showing the overvoltage of a hydroxide catalyst formed using various metal-containing supports according to one embodiment of the present invention.

[0121] Referring to Table 1 and Fig. 16, the overvoltage was found to be less than 350 mV in all cases.

[0122] Compared to the values ​​of 383 mV (nickel) and 376 mV (stainless steel 304) of the above comparative examples in which no hydroxide was formed, it can be seen that the overvoltage in all cases is low.

[0123] In the case of nickel as the metal-containing support, the effect of hydrogen chloride gas treatment was relatively small. On the other hand, in the case of stainless steel 304 (SUS304), Inconel 600, and Incoloy 800 as the metal-containing support, the overvoltage decreased when hydrogen chloride gas treatment was performed, and the overvoltage decreased further as the hydrogen chloride gas treatment time increased. However, in the case of Incoloy 800, the overvoltage was lower when hydrogen chloride gas treatment was performed for 1 hour than when it was performed for 3 hours.

[0124] Therefore, by forming a hydroxide structure, the overvoltage can be reduced, and thus an efficient water electrolysis electrode can be provided with high oxygen evolution reaction activity.

[0125] Below, we analyze the experimental results for hydroxide catalysts formed using metal-containing supports with various nickel surface layers. Manufacturing conditions other than those described below are as described above.

[0126] Table 2 shows the process conditions for forming hydroxide catalysts using metal-containing supports having various nickel surface layers and the overvoltage of the formed hydroxide catalysts.

[0127] Classification Metal-containing support Nickel surface layer formation method Homogenization heat treatment Hydrogen chloride gas reaction Overvoltage Experimental example 13 SUS304 Electroless plating None None 370 mV Experimental example 14 SUS304 Electroless plating 400 o C, 5hr1hr270mVExperimental Example 15SUS304 Electroless Plating 400 o C, 5hr3hr265mVExperimental Example 16SUS304 Electroless Plating 600 o C, 5hr1hr267mVExperimental Example 17SUS304 Electroless Plating 600 o C, 5hr3hr206mVExperimental Example 18SUS304 Electroless Plating 600 o C, 7hr1hr279mVExperimental Example 19SUS304 Electroless Plating 600 o C, 9hr1hr260 mVExperimental Example 20Fe Electroless PlatingNoneNone400 mVExperimental Example 21Fe Electroless Plating400 o C, 5hr1hr276mVExperimental Example 22Fe Electroless Plating 400 o C, 5hr3hr273mVExperimental Example 23Fe Electroless Plating600 o C, 5hr1hr247mVExperimental Example 24Fe Electroless Plating600 o C, 5hr3hr307mVExperimental Example 25Fe Electroless Plating 600 o C, 7hr1hr288mVExperimental Example 26Fe Electroless Plating600 o C, 9hr1hr290 mV

[0128] FIG. 17 is a graph showing the overvoltage of a hydroxide catalyst formed using a metal-containing support having various nickel surface layers according to an embodiment of the present invention.

[0129] Referring to Table 2 and Fig. 17, the overvoltage was found to be less than 400 mV in all cases.

[0130] Compared to the values ​​of 383 mV (nickel) and 376 mV (stainless steel 304) of the comparative examples in which no hydroxide was formed, Experimental Examples 13 (SUS304) and 20 (Fe), in which homogenization heat treatment was not performed after forming a nickel surface layer by electroless plating, had high overvoltages. Therefore, it is desirable to perform homogenization heat treatment to obtain a low overvoltage.

[0131] In the case where the metal-containing support having the nickel surface layer was stainless steel 304 and iron, the overvoltage was in the range of 200 mV to 310 mV after homogenization heat treatment and reaction with hydrogen chloride gas (HCl), and the overvoltage value for stainless steel 304 was slightly lower than that for iron. The change in overvoltage according to the temperature and time of homogenization heat treatment was minimal.

[0132] In the case where the metal-containing support having the above nickel surface layer is stainless steel 304, 600 o Experimental Example 17, which was homogenized and heat-treated at C temperature for 5 hours and reacted with hydrogen chloride gas for 3 hours, showed the lowest overvoltage of 206 mV.

[0133] When the metal-containing support having the nickel surface layer is iron, 600 o Experimental example 23, which was homogenized and heat-treated at C temperature for 5 hours and reacted with hydrogen chloride gas for 1 hour, showed the lowest overvoltage of 247 mV.

[0134] It will be apparent to those skilled in the art that the technical concept of the present invention described above is not limited to the aforementioned embodiments and the attached drawings, and that various substitutions, modifications, and changes are possible without departing from the technical concept of the present invention. Therefore, the scope of the present invention should be determined by the claims set forth below.

Claims

1. A step of providing a metal-containing support; A step of forming a metal precursor layer on the surface of the metal-containing support by reacting the metal-containing support with an acidic gas; and A step of forming a hydroxide structure by inducing a reaction between the metal precursor layer and the hydroxide solution, A method for producing a hydroxide catalyst.

2. In paragraph 1, The step of forming the above metal precursor layer is: Compared to the metal or metal oxide constituting the metal-containing support, the free energy of the metal precursor constituting the metal precursor layer is performed in a low temperature range. A method for producing a hydroxide catalyst.

3. In paragraph 1, The step of forming the above metal precursor layer is: 20 o C to 1000 o C range of temperatures for 1 minute to 48 hours, A method for producing a hydroxide catalyst.

4. In paragraph 1, The step of forming the above hydroxide structure is: After the hydroxide solution is added to the metal precursor layer, 0 o C to 100 o It is performed by maintaining it for 1 second to 24 hours at a temperature in the range of C. A method for producing a hydroxide catalyst.

5. In paragraph 1, The above metal-containing support, Comprising at least one of a nickel-containing metal and a nickel-containing metal-ceramic composite, A method for producing a hydroxide catalyst.

6. In paragraph 1, The above metal-containing support, Containing at least one of pure nickel, nickel alloy, Inconel alloy, Incoloy alloy and nickel-containing stainless steel; A method for producing a hydroxide catalyst.

7. In paragraph 1, The above acidic gas is, Containing at least one of hydrogen chloride gas, nitric acid gas, sulfuric acid gas, chlorine gas, ammonia gas, hydrogen nitride gas, hydrogen sulfide gas, hydrogen fluoride gas, perchloric acid gas, acetic acid gas, acrylic acid gas, and acetylaceton acid gas. A method for producing a hydroxide catalyst.

8. In paragraph 1, The partial pressure of the above acid gas ranges from 1% to 50%. A method for producing a hydroxide catalyst.

9. In paragraph 1, The above metal precursor layer, Containing at least one of metal chloride, metal nitrate, metal sulfate, metal sulfide, metal fluoride, metal perchlorate, metal acetate, metal acrylate, and metal acetylacetonate. A method for producing a hydroxide catalyst.

10. In paragraph 1, The above metal precursor layer, Comprising at least one of nickel chloride, nickel nitrate, nickel sulfate, nickel sulfide, nickel fluoride, nickel perchlorate, nickel acetate, nickel acrylate, and nickel acetylacetonate. A method for producing a hydroxide catalyst.

11. In paragraph 1, The above hydroxide solution is, Containing sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, strontium hydroxide, ammonium hydroxide or a mixture thereof; A method for producing a hydroxide catalyst.

12. In paragraph 1, Further comprising a step of washing and drying the above hydroxide structure, A method for producing a hydroxide catalyst.

13. In paragraph 1, The step of providing a metal-containing support is: A method comprising: performing a step of providing a metal-containing support having a nickel surface layer; A method for producing a hydroxide catalyst.

14. In paragraph 13, The step of providing the metal-containing support having the nickel surface layer is: A step of forming a nickel surface layer on the surface of the metal-containing support; and Comprising a step of homogenizing heat treatment of the nickel surface layer, A method for producing a hydroxide catalyst.

15. In paragraph 14, The step of forming the above nickel surface layer is: The nickel surface layer is formed on the surface of the metal-containing support by using electrolytic plating, electroless plating, physical vapor deposition, chemical vapor deposition, or galvanic substitution. A method for producing a hydroxide catalyst.

16. In paragraph 14, The step of homogenizing the nickel surface layer is as follows: 200 under reducing atmosphere o C to 1200 o Performed at temperatures ranging from C for 10 minutes to 10 hours, A method for producing a hydroxide catalyst.

17. In paragraph 14, The above metal-containing support, Containing cast iron, steel, stainless steel, copper, aluminum or alloys thereof; A method for producing a hydroxide catalyst.

18. An electrode support; and a hydroxide catalyst body positioned on the electrode support, The above hydroxide catalyst comprises a hydroxide structure formed by reacting a metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support, and inducing a reaction between the metal precursor layer and a hydroxide solution. electrode.

19. In paragraph 18, The above hydroxide structure is, having an equivalent diameter in the range of 1 μm to 20 μm, Indicates overvoltage in the range of 50 mV to 400 mV, electrode.

20. Containing an anode, cathode and electrolyte; The anode comprises an electrode support; and a hydroxide catalyst body positioned on the electrode support, The above hydroxide catalyst comprises a hydroxide structure formed by reacting a metal-containing support with an acidic gas to form a metal precursor layer on the surface of the metal-containing support, and inducing a reaction between the metal precursor layer and a hydroxide solution. Electrolysis system.

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