Method for manufacturing an anion exchange membrane water electrolysis system

Abstract

The present invention provides a method for manufacturing an anion exchange membrane water electrolysis system that exhibits excellent water electrolysis performance, as well as improved durability and efficiency.

Description

Technical Field

[0001] Cross-reference of related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0061678 filed on May 12, 2023, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] The present invention relates to a method for manufacturing an anion exchange membrane water electrolysis system that exhibits excellent water electrolysis performance, improved durability, and efficiency.

Background Art

[0003] The importance of technologies that can environmentally friendly produce hydrogen, which is a next-generation energy source capable of solving the depletion of fossil fuels and environmental pollution, has emerged.

[0004] As a result, research on water electrolysis technology using an electrolysis method has been actively conducted. Representative water electrolysis technologies include proton exchange membrane water electrolysis (PEMWE), anion exchange membrane water electrolysis (AEMWE), and alkaline water electrolysis (AWE).

[0005] In alkaline water electrolysis, nickel-based oxides and cobalt-based oxides are generally widely used as reduction electrode and oxidation electrode catalyst materials, and an alkaline aqueous solution such as KOH is used as an electrolyte. Alkaline electrolysis has the advantage of not requiring a noble metal catalyst and being drivable at a relatively low temperature. However, it has the disadvantages of low hydrogen production rate and a large size of the designed system for hydrogen production. In addition, the liquid alkaline electrolyte is likely to leak, and the leakage of the electrolyte increases the resistance and decreases the current density, ultimately reducing the water electrolysis efficiency.

[0006] On the other hand, cation exchange membrane water electrolysis is a water electrolysis system that uses a solid electrolyte membrane, such as Nafion, instead of a liquid electrolyte. Because the solid electrolyte membrane occupies a smaller volume than a liquid electrolyte, the system size can be reduced and a high current density can be provided. However, since it is operated in an acidic environment, the reducing electrode and oxidizing electrode catalysts must be platinum-based catalysts such as IrO2 and Pt that can withstand the strong corrosiveness of acid. The use of expensive platinum-based catalysts increases the cost of hydrogen production and is the biggest constraint on the commercialization of cation exchange membrane water electrolysis.

[0007] In contrast, anion exchange membrane water electrolysis is a system that leverages the advantages of existing systems while overcoming their disadvantages. Because it operates in an alkaline environment, non-platinum metals can be used as catalysts, and a remarkable energy density can be obtained in a compact system. However, non-platinum metal catalysts have the disadvantage of lower water electrolysis efficiency because their catalytic activity is lower than that of platinum metal catalysts.

[0008] Therefore, research and development is being conducted on the development of catalysts and anion exchange membrane water electrolysis systems that can improve water electrolysis efficiency by possessing excellent catalytic activity. In the case of catalysts, research is mainly progressing in the direction of applying previously developed alkaline half-cell catalysts to anion exchange membrane systems. However, the applied catalysts still suffer from problems such as low catalytic activity and degraded durability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to solve the problems of the prior art and provide a method for manufacturing an anion exchange membrane water electrolysis system that exhibits excellent water electrolysis performance along with improved durability and efficiency.

[0010] The present invention also aims to provide an anion exchange membrane water electrolysis system manufactured by the above manufacturing method.

[0011] The present invention further aims to provide an activation method that can improve the performance of an anion exchange membrane water electrolysis system. [Means for solving the problem]

[0012] A method for manufacturing an anion exchange membrane water electrolysis system according to one embodiment of the present invention is: The steps include manufacturing the preliminary reduction electrode and the oxidation electrode, respectively. The steps include: manufacturing a pre-film-electrode assembly by interposing an anion exchange membrane between the pre-reduction electrode and the oxidation electrode; The step includes supplying an alkaline aqueous solution to the pre-film-electrode assembly to activate the pre-reduction electrode, The aforementioned pre-reduction electrode contains NiMo alloy particles in which the molar ratio of Ni to Mo is 1:1 to 6:1 and the oxidation state of Mo is 4+, 5+, or 6+. The aforementioned activation is 25-200 mA / cm². 2 This is done by applying a current at a certain current density and maintaining it at 50-60°C for 90-360 minutes.

[0013] Furthermore, an anion exchange membrane water electrolysis system according to another embodiment of the present invention is manufactured by the method for manufacturing the anion exchange membrane water electrolysis system described above, and comprises a reducing electrode containing a particulate NiMo-based alloy catalyst, an oxidizing electrode, an anion exchange membrane interposed between the reducing electrode and the oxidizing electrode, and an alkaline aqueous solution, wherein the NiMo-based alloy catalyst contains Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation state of Mo is 5+ or 6+.

[0014] A method for activating an anion exchange membrane water electrolysis system according to yet another embodiment of the present invention includes a pre-reduction electrode, an oxidation electrode, and an anion exchange membrane interposed between the pre-reduction electrode and the oxidation electrode, wherein the pre-reduction electrode contains NiMo alloy particles with Ni and Mo in a molar ratio of 1:1 to 6:1 and the oxidation state of Mo being 4+, 5+, or 6+, and an alkaline aqueous solution is supplied to the pre-anion exchange membrane water electrolysis system at 25 to 200 mA / cm². 2The process includes a step of activating the pre-reducing electrode by applying a current at a current density and maintaining it at 50-60°C for 90-360 minutes. [Effects of the Invention]

[0015] The manufacturing method according to the present invention makes it possible to produce an anion exchange membrane water electrolysis system that exhibits excellent water electrolysis performance, as well as improved durability and efficiency. [Brief explanation of the drawing]

[0016] [Figure 1A] This graph shows the adsorption energies of H2O, MoO2, and H2O / MoO2 clusters on the surface of a Ni24Mo4 alloy. [Figure 1B] This graph shows the adsorption energy of the hydrogen intermediate H* at its adsorption site. [Figure 2] This is a schematic diagram illustrating the hydrogen formation reaction mechanism of NiMo-based alloys in an alkaline atmosphere. [Figure 3] This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a dual-feed alkaline aqueous solution circulation device according to one embodiment of the present invention. [Figure 4] This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a both-feeding alkaline aqueous solution circulation device according to another embodiment of the present invention. [Figure 5] This is a schematic diagram illustrating an anion exchange membrane water electrolysis system including an anode feeding type alkaline aqueous solution circulation device according to yet another embodiment of the present invention. [Figure 6A] This graph shows the BET analysis results for NiMo-based alloy particles from manufacturing example 1. [Figure 6B] This graph shows the BET analysis results for NiMo-based alloy particles from manufacturing example 2. [Figure 6C] This graph shows the BET analysis results for NiMo-based alloy particles from manufacturing example 3. [Figure 6D]This graph shows the BET analysis results for NiMo-based alloy particles from manufacturing example 4. [Figure 7] This graph shows the results of evaluating the change in the activity of hydrogen evolution reactions in NiMo alloys according to the molar ratio of Ni and Mo, using linear sweep voltammetry (LSV). [Figure 8] This graph shows the results of analyzing the initial oxidation state of Mo in NiMo-based alloys of manufacturing examples 1-4 using X-ray photoelectron spectroscopy (XPS). [Figure 9] This graph shows the results of XPS analysis of the change in the oxidation state of Mo in Ni3Mo alloy before and after activation. [Figure 10] This graph shows the results of observing the change in current due to voltage control in an anion exchange membrane water electrolysis system activated by increasing and decreasing the applied voltage. [Figure 11] This graph shows the results of observing the change in current due to voltage control in an anion exchange membrane water electrolysis system activated by applying a current at a constant current density and maintaining it for a certain period of time. [Figure 12] This graph shows the polarization evaluation results for anion exchange membrane water electrolysis systems activated under current densities of 25 mA / cm², 50 mA / cm², 100 mA / cm², and 200 mA / cm², respectively. [Figure 13] This graph shows the durability evaluation results for anion exchange membrane water electrolysis systems activated under current densities of 25 mA / cm², 50 mA / cm², 100 mA / cm², and 200 mA / cm², respectively. [Figure 14] This is a phase diagram of Mo according to pH, disclosed in the literature "Anatolyevich, Pavel. 'The Revised Pourbaix Diagram for Molybdenum.' HMo2.10:3." [Figure 15]This graph shows the results of X-ray fluorescence (XRF) analysis of the remaining amount of Mo in an anion exchange membrane water electrolysis system activated under current densities of 25 mA / cm², 50 mA / cm², 100 mA / cm², and 200 mA / cm². [Figure 16] This graph shows the results of an evaluation of the effect of activation time on the performance development of NiMo-based alloys. [Figure 17] This graph shows the results of the polarization evaluation of an anion exchange membrane water electrolysis system using a circulating alkaline aqueous solution method. [Figure 18] This graph shows the durability evaluation results for an anion exchange membrane water electrolysis system. [Modes for carrying out the invention]

[0017] In the present invention, terms such as "first," "second," etc., are used to describe various components, and these terms are used solely for the purpose of distinguishing one component from other components.

[0018] Furthermore, the terms used herein are used solely to describe exemplary embodiments and are not intended to limit the invention. A singular expression includes plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the existence of implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the possibility of the existence or addition of one or more other features, figures, stages, components, or combinations thereof.

[0019] Furthermore, in the present invention, when it is referred to that each layer or element is formed "on top of" each layer or element, it means that each layer or element is formed directly on top of each layer or element, or that other layers or elements may be formed additionally between each layer, on the object, or on the substrate.

[0020] Furthermore, in the present invention, "reduction electrode," "membrane-electrode assembly," and "anion exchange membrane water electrolysis system" refer to the activated reduction electrode, membrane-electrode assembly, and anion exchange membrane water electrolysis system, respectively, while "pre-reduction electrode," "pre-membrane-electrode assembly," and "pre-anion exchange membrane water electrolysis system" refer to the unactivated reduction electrode, membrane-electrode assembly, and anion exchange membrane water electrolysis system, respectively.

[0021] Furthermore, "NiMo-based alloy particles" refer to the unactivated alloy particles used in the manufacture of the preliminary reduction electrode, while "NiMo-based alloy catalyst" or "particulate NiMo-based alloy catalyst" refers to the activated alloy particles.

[0022] While the present invention can take on various forms through diverse modifications, specific embodiments are described in detail below. However, it should be understood that this is not intended to limit the present invention to any particular disclosure, but rather to include all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0023] The following describes in detail a method for manufacturing an anion exchange membrane water electrolysis system according to an embodiment of the invention, the anion exchange membrane water electrolysis system manufactured thereby, and an activation method that can improve the performance of the anion exchange membrane water electrolysis system.

[0024] A method for manufacturing an anion exchange membrane water electrolysis system according to one embodiment of the present invention is: The process involves the steps of manufacturing the preliminary reduction electrode and the oxidation electrode, respectively (Step 1), Step 2 involves interposing an anion exchange membrane between the aforementioned pre-reduction electrode and oxidizing electrode to manufacture a pre-membrane-electrode assembly, Step 3 includes the step of supplying an alkaline aqueous solution into the pre-film-electrode junction to activate the pre-reduction electrode, At this time, the pre-reducing electrode contains NiMo-based alloy particles, the NiMo-based alloy particles contain Ni and Mo in a molar ratio of 1:1 to 6:1, and the oxidation state of Mo is 4+, 5+, or 6+. The aforementioned activation is 25-200 mA / cm². 2 This is done by applying a current at a certain current density and maintaining it at 50-60°C for 90-360 minutes.

[0025] A reducing electrode is produced as a result of activation of the pre-reducing electrode. The reducing electrode contains a particulate NiMo-based alloy catalyst derived from the NiMo-based alloy particles, the NiMo-based alloy catalyst containing Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation state of Mo is 5+ or 6+.

[0026] The inventors discovered that with conventional NiMo-based alloy catalysts developed as non-platinum catalysts for anion exchange membrane water electrolysis, Mo leaches out in an alkaline atmosphere during operation of the anion exchange membrane water electrolysis system, resulting in a decrease in water electrolysis performance. Through elucidating the performance expression mechanism of NiMo-based alloys, the inventors controlled and optimized the molar ratio and oxidation state of the NiMo alloy, the activation method of the water electrolysis system, and ultimately, the electrolyte supply method. As a result, they were able to produce an anion exchange membrane water electrolysis system that, despite containing a non-platinum catalyst, exhibits excellent water electrolysis performance at the level of a platinum catalyst. Furthermore, they confirmed that the durability and efficiency of the anion exchange membrane water electrolysis system were improved, and that there was little performance degradation even during long-term operation, thus completing the present invention.

[0027] Specifically, NiMo-based alloy particles containing Ni and Mo in various molar ratios were manufactured, and after fabricating a preliminary reduction electrode and a preliminary anion exchange membrane water electrolysis system containing these particles, they were activated and their cell performance was confirmed. As a result, it was confirmed that significant leaching of Mo from the NiMo-based alloy occurred in an alkaline atmosphere when the water electrolysis system was operated, causing a change in the molar ratio of Ni and Mo in the alloy, as well as the oxidation state of Mo.

[0028] Subsequently, thermodynamic calculations were used to mechanistically investigate the reason for the leaching of Mo. Specifically, Ni 24When calculating the energy required for the leakage of one Mo atom at a time from a Mo8 alloy, all processes proceeded in a stabilizing direction (see Table 3 in Experimental Example 3 below). Furthermore, computational chemistry confirmed that NiMo-based alloys are stable when all Mo atoms present on the surface are leached out in an alkaline atmosphere.

[0029] Figure 1A shows Ni 24 Figure 1B shows the adsorption energies of H2O, MoO2, and H2O / MoO2 clusters on the surface of a Mo4 alloy, while Figure 1B shows the adsorption energies of hydrogen intermediate H* at adsorption sites.

[0030] Calculations of the adsorption energy in Figure 1A confirmed that the Mo lost during the activation of the water electrolysis system adsorbed with water and existed in the form of H2O / MoO2 clusters. Furthermore, calculations of the adsorption energy at the adsorption sites in Figure 1B confirmed that the intermediate product, hydrogen, is more stabilized when adsorbed on the Ni side of the Mo site. From these results, it is possible to predict a mechanism in which H2O / MoO2 clusters are adsorbed on the Ni surface, and after water splitting, hydrogen moves to the Ni surface to generate hydrogen.

[0031] Figure 2 is a schematic diagram illustrating the hydrogen production reaction mechanism of NiMo-based alloys, specifically Ni3Mo alloys, in an alkaline atmosphere. Figure 2 is merely an example illustrating the present invention, and the present invention is not limited thereto.

[0032] Referring to Figure 2, the hydrogen production reaction of NiMo alloys in an alkaline atmosphere consists of the following mechanisms: (1) leaching of all Mo from the NiMo alloy surface, (2) formation of Mo oxide from the leached Mo, (3) re-adsorption of H2O / Mo oxide to the bare Ni surface, (4) dissociation of water and adsorption of hydrogen intermediate H* at the Ni site (dual active site), and (5) H2 production by the Heyrovsky or Tafel reaction.

[0033] Therefore, the structure of a NiMo-based alloy catalyst that is stable and highly active in an alkaline atmosphere is such that the catalyst surface is made of Ni, and Mo dissolves to become MoO2, and then adsorbs onto the Ni surface in the form of H2O / Mo oxide clusters with H2O. At this time, the molar ratio of Ni to Mo in the alloy catalyst is 6:1 to 101:1, and the oxidation state of Mo is 5+ or 6+.

[0034] When the above molar ratio conditions are satisfied, only the Mo on the surface of the NiMo alloy is selectively dissolved, and thereafter, the generated Mo oxide can form clusters with water and be sufficiently adsorbed onto the Ni surface. If only Mo is present on the surface of the alloy catalyst, as in conventional methods, it is difficult to control the molar ratio of Ni to Mo and the oxidation state of Mo to satisfy the above conditions.

[0035] Based on the performance mechanism of NiMo-based alloys as elucidated above, the present invention realizes a NiMo-based alloy catalyst structure that exhibits stable and high activity by controlling and optimizing the molar ratio of Ni and Mo, the oxidation state of Mo, the activation method of the water electrolysis system, and ultimately, the electrolyte supply method in the NiMo-based alloy.

[0036] As a result, the reducing electrode in the anion exchange membrane water electrolysis system manufactured by the method for manufacturing an anion exchange membrane water electrolysis system according to the present invention contains a NiMo-based alloy catalyst with a stable and highly active structure.

[0037] Specifically, the anion exchange membrane water electrolysis system produced by the method for producing an anion exchange membrane water electrolysis system according to the present invention comprises a reducing electrode containing a particulate NiMo-based alloy catalyst, an oxidizing electrode, an anion exchange membrane interposed between the reducing electrode and the oxidizing electrode, and an alkaline aqueous solution, wherein the NiMo-based alloy catalyst contains Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation state of Mo is 5+ or 6+.

[0038] In this invention, the molar ratio of Ni to Mo in the NiMo-based alloy catalyst is determined by XRF analysis. The specific analytical method and conditions are described in the experimental example below.

[0039] Furthermore, the oxidation state of Mo in NiMo-based alloy catalysts can be determined by XPS analysis. The specific analytical methods and conditions are described in the experimental example below.

[0040] Furthermore, the NiMo-based alloy catalyst includes a Ni layer on its surface.

[0041] The aforementioned Ni layer is formed by the leaching of Mo from the surface of NiMo-based alloy particles during the activation process.

[0042] On the other hand, the leaching rates of each element in NiMo-based alloys before and after activation can be confirmed by XRF analysis of the alloy. The specific analytical methods and conditions are described in the experimental examples below.

[0043] Furthermore, the NiMo-based alloy catalyst may be manufactured from NiMo-based alloy particles, and these NiMo-based alloy particles may be manufactured by a powder method utilizing a coprecipitation reaction. As a result, the NiMo-based alloy catalyst has a particulate (powder) form and a relatively smaller average particle diameter and a larger specific surface area compared to NiMo-based alloys manufactured by conventional methods such as electroplating or vapor deposition.

[0044] Furthermore, the NiMo-based alloy catalyst is a porous particle having multiple pores within the particle.

[0045] Furthermore, in the conventional manufacturing of electrodes using alloy catalysts with average particle sizes at the nanoscale, the catalyst layer is formed on the electrode substrate by electroplating or vapor deposition, resulting in a limited specific surface area of ​​the manufactured electrode. In contrast, in the present invention, a slurry for forming a preliminary reduction electrode is manufactured by dispersing particulate alloy in a solvent, and then this slurry is applied to a release film, dried, and separated to produce a catalyst layer, which is then used as the reduction electrode itself. As a result, the manufactured reduction electrode has a larger specific surface area compared to conventional methods, and consequently exhibits superior catalytic activity.

[0046] Furthermore, the NiMo-based alloy catalyst is present in the reducing electrode at a concentration of 1.0 mg / cm³. 2 It may be included with a higher loading amount than the above.

[0047] On the other hand, the anion exchange membrane water electrolysis system according to the present invention includes a membrane electrode assembly (MEA) as a unit cell, which consists of a reducing electrode (cathode, negative electrode) containing the particulate NiMo-based alloy catalyst, an oxidizing electrode (anode, positive electrode), and an anion exchange membrane interposed between the reducing electrode and the oxidizing electrode.

[0048] The anion exchange membrane water electrolysis system may include a plurality of membrane-electrode assemblies, and the number of membrane-electrode assemblies can be appropriately determined according to the performance required of the water electrolysis system.

[0049] The plurality of film-electrode assemblies are connected to each other and stacked to form a stack.

[0050] As a result, the anion exchange membrane water electrolysis system includes a plurality of the membrane-electrode assemblies and a stack that electrolyzes an alkaline aqueous solution to generate hydrogen and oxygen, and optionally further includes an alkaline aqueous solution circulation device that supplies the alkaline aqueous solution to the stack, a product gas exhaust device for exhausting the oxygen and hydrogen generated in the stack, and a power supply device that applies and controls voltage and current to the stack.

[0051] In the aforementioned film-electrode assembly, a hydrogen evolution reaction (HER) occurs at the reducing electrode due to a reduction catalyst, resulting in the production of hydrogen (H2) and hydroxide ions (OH). - ) is produced. At this time, the particulate NiMo-based alloy catalyst is included as a reduction catalyst.

[0052] Typically, the electrodes of a water electrolysis system include a catalyst layer containing a catalyst and an electrode substrate for supporting the catalyst layer. However, the reducing electrode in the present invention does not include an electrode substrate and consists only of a catalyst layer containing the NiMo-based alloy catalyst.

[0053] On the other hand, at the oxidation electrode, an oxygen evolution reaction (OER) occurs catalyzed by the oxidation catalyst, and hydroxide ions generated at the reduction electrode and diffused through the anion exchange membrane are oxidized to produce water and oxygen.

[0054] As the oxidation catalyst, one or more selected from the group consisting of Ni, NiCoFe, Ir, and NiFe-layered double hydroxide (LDH) can be used.

[0055] The oxidation electrode may further include an electrode substrate for supporting the catalyst layer, along with a catalyst layer containing the oxidation catalyst. The electrode substrate is a conductive porous material.

[0056] The oxide electrode can be manufactured by conventional methods. For example, the oxide electrode may be manufactured by a manufacturing method that includes the steps of applying an oxide electrode forming slurry containing an oxidation catalyst, a binder, and a solvent onto a release film, drying it, and then separating it from the release film, or by a manufacturing method that includes the steps of applying, plating, or vapor-depositing an oxidation catalyst onto an electrode substrate.

[0057] Furthermore, the anion exchange membrane is OH -It plays a role in moving ions from the reduction electrode to the oxidation electrode. As the anion exchange membrane, any ordinary anion exchange membrane used in a water electrolysis system such as Trimethyl ammonium functionalized polystyrenes can be used without special restrictions. Additionally, it may be commercially available and used. In this case, as an example, the Sustainion TM X37-50 grade RT anion exchange membrane can be mentioned.

[0058] Further, the membrane-electrode assembly can optionally further include a gasket that seals and fixes the periphery of the membrane-electrode assembly together with the oxidation electrode, reduction electrode, and anion exchange membrane.

[0059] A plurality of membrane-electrode assemblies of the above structure are connected in series and stacked to form a stack.

[0060] Moreover, the stack in the anion exchange membrane water electrolysis system can further include one or more of a porous transport layer and a separator (separator or bipolar plate) together with the membrane-electrode assembly.

[0061] The porous transport layer is located on the electrode side that does not contact the anion exchange membrane in the membrane-electrode assembly, conducts electricity, moves the alkaline aqueous solution to the electrode, and discharges the generated gas to the outside. The porous transport layer may be located on either one of the reduction electrode and the oxidation electrode, or may be located with respect to both. Nickel foam may be used for the porous transport layer for the reduction electrode located on the reduction electrode side. Also, carbon paper may be used for the porous transport layer for the oxidation electrode located on the oxidation electrode side.

[0062] Further, the separator is located on both sides of the membrane-electrode assembly and serves to connect and support two adjacent membrane-electrode assemblies in series.

[0063] Furthermore, since the separation plate is a metal plate such as Ni, it can conduct electricity applied from the power supply. In addition, a channel is formed in the separation plate, allowing the alkaline aqueous solution supplied from the alkaline aqueous solution circulation device to be moved to the porous transport layer. Moreover, the separation plate can discharge the generated gas to the outside and transfer the heat generated in the reaction.

[0064] Furthermore, the anion exchange membrane water electrolysis system according to the present invention may further include an alkaline aqueous solution circulation device that supplies and discharges an alkaline aqueous solution to the stack.

[0065] The aforementioned alkaline aqueous solution may contain one or more alkali metal hydroxides, such as potassium hydroxide and sodium hydroxide. More specifically, it may contain the alkali metal hydroxide at a concentration of 0.1 M to 1 M. Even more specifically, the alkaline aqueous solution may be an aqueous potassium hydroxide solution with a concentration of 0.1 to 1 M.

[0066] The alkaline aqueous solution circulation device may specifically include a tank for storing the alkaline aqueous solution, a temperature control device for controlling the temperature by supplying heat to the water electrolysis system, and a flow control device such as a pump for controlling and maintaining a constant flow rate of the alkaline aqueous solution.

[0067] Furthermore, one or more of the alkaline aqueous solution circulation devices may be included in the water electrolysis system.

[0068] The alkaline aqueous solution circulation device can be classified into three types based on the method of supplying the alkaline aqueous solution: both feeding, anode feeding, and dual feeding. Specifically, the both feeding method supplies the alkaline aqueous solution to both the oxidizing electrode and the reducing electrode from a single alkaline aqueous solution circulation device, and one alkaline aqueous solution circulation device is included in the anion exchange membrane water electrolysis system. The alkaline aqueous solution circulation device in the both feeding method is located connected to both the oxidizing electrode and the reducing electrode, and supplies the alkaline aqueous solution to both electrodes. The anode feeding method supplies the alkaline aqueous solution to the oxidizing electrode, and in this case, one alkaline aqueous solution circulation device is also included in the water electrolysis system. The alkaline aqueous solution circulation device in the anode feeding method is located connected to the oxidizing electrode, and supplies the alkaline aqueous solution to the oxidizing electrode. On the other hand, the dual-feeding method is a method of supplying alkaline aqueous solution to each electrode from an alkaline aqueous solution circulation device provided for each of the oxidizing electrode and the reducing electrode. The alkaline aqueous solution circulation device in the dual-feeding method consists of an alkaline aqueous solution circulation device for the oxidizing electrode and an alkaline aqueous solution circulation device for the reducing electrode, which are located connected to the oxidizing electrode and the reducing electrode, respectively.

[0069] Figure 3 is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a dual-feeding alkaline aqueous solution circulation device according to one embodiment of the present invention; Figure 4 is a schematic diagram illustrating an anion exchange membrane water electrolysis system including a boss-feeding alkaline aqueous solution circulation device according to another embodiment of the present invention; and Figure 5 is a schematic diagram illustrating an anion exchange membrane water electrolysis system including an anode-feeding alkaline aqueous solution circulation device according to yet another embodiment of the present invention. Figures 3 to 5 are merely examples to illustrate the present invention, and the present invention is not limited thereto.

[0070] On the other hand, the circulation method of the alkaline aqueous solution in an anion exchange membrane water electrolysis system affects the amount of Mo lost and the performance, particularly the durability, of the anion exchange membrane water electrolysis system.

[0071] Specifically, in the boss feeding method, the dissolution of Mo, which occurs when the alkaline aqueous solution comes into direct contact with the NiMo alloy particles, and the dissolution of Mo, which is anionized and moves to the reducing electrode, occur simultaneously. In contrast, in the anode feeding method, the NiMo alloy particles do not come into direct contact with the alkaline aqueous solution. Therefore, the anode feeding method exhibits a lower Mo loss rate than the boss feeding method.

[0072] Furthermore, in terms of the performance of the water electrolysis system, a dual-feeding system, in which two alkaline aqueous solution circulators supply alkaline aqueous solution to the oxidizing and reducing electrodes respectively, can produce hydrogen at a lower voltage than a boss-feeding system, in which one alkaline aqueous solution circulator supplies alkaline aqueous solution to both the oxidizing and reducing electrodes.

[0073] Furthermore, the anion exchange membrane water electrolysis system according to the present invention may further include a generated gas discharge device and a power supply device, along with the stack and the alkaline aqueous solution circulation device.

[0074] Furthermore, the generated gas discharge device is connected to the outlet of the alkaline aqueous solution circulation device, so that the gas generated in the water electrolysis system is discharged mixed with the alkaline aqueous solution, or discharged independently. The generated gas discharge device can remove gas at atmospheric pressure (1±0.1), and pressurization can be applied by adjusting the flow rate.

[0075] The generated gas discharge device may include an oxidizing electrode generated gas discharge system (or oxidizing electrode generated gas discharge unit) for discharging oxygen generated at the oxidizing electrode of an anion exchange membrane water electrolysis system, and a reducing electrode generated gas discharge system (or reducing electrode generated gas discharge unit) for discharging hydrogen generated at the reducing electrode.

[0076] Furthermore, the power supply plays a role in regulating the current and voltage within the system, such as outputting the voltage necessary for electrolysis to the stack of the anion exchange membrane water electrolysis system, specifically the oxidizing electrode and the reducing electrode, and consuming and removing residual voltage within the stack.

[0077] As a result, when an alkaline aqueous solution is supplied to the anion exchange membrane from the alkaline electrolyte circulation device, and a DC voltage is applied to the oxidizing electrode and the reducing electrode from the power supply, hydroxide ions (OH) are produced as decomposition products of the alkaline aqueous solution in the anion exchange membrane. - The oxidizing catalyst oxidizes the surface of the oxidizing electrode, generating oxygen, water, and electrons. The electrons then move along the external wire to the reducing electrode, where they undergo a catalytic reaction with the water on the surface of the reducing electrode to produce hydrogen and hydroxide ions (OH). - This generates ) the oxygen generated at the oxidation electrode and the hydrogen generated at the reduction electrode, respectively, which are then discharged outside the anion exchange membrane water electrolysis system via the oxidizing electrode generated gas discharge system and the reduction electrode generated gas discharge system.

[0078] The anion exchange membrane water electrolysis system according to the present invention having the above structure is manufactured by first producing a pre-membrane-electrode assembly including a pre-reduction electrode and an oxidation electrode, and an anion exchange membrane interposed between the pre-reduction electrode and the oxidation electrode, followed by a circulation and activation step of an alkaline aqueous solution. During the activation step, the molar ratio of Ni to Mo and the oxidation number of Mo in the NiMo-based alloy particles in the pre-reduction electrode are changed via the above mechanism.

[0079] As described above, the method for manufacturing the anion exchange membrane water electrolysis system specifically includes the steps of: manufacturing a pre-reduction electrode and an oxidation electrode (step 1); manufacturing a pre-membrane-electrode assembly by interposing an anion exchange membrane between the pre-reduction electrode and the oxidation electrode (step 2); and supplying an alkaline aqueous solution into the pre-membrane-electrode assembly to activate the pre-reduction electrode (step 3), wherein the pre-reduction electrode contains NiMo-based alloy particles, the NiMo-based alloy particles contain Ni and Mo in a molar ratio of 1:1 to 6:1, the oxidation state of Mo is 4+, 5+, or 6+, and the activation is 25 to 200 mA / cm². 2 This is done by applying a current at a certain current density and maintaining it at 50-60°C for 90-360 minutes.

[0080] To explain each stage in detail, Stage 1 is the stage in which the preliminary reduction electrode and the oxidation electrode are manufactured, respectively.

[0081] The aforementioned pre-reduction electrode can be manufactured by a manufacturing method that includes the steps of applying a slurry for forming a pre-reduction electrode, containing the NiMo-based alloy particles, binder, and solvent, onto a release film, drying it, and then separating it from the release film.

[0082] The NiMo alloy particles contained in the aforementioned pre-reducing electrode specifically contain Ni and Mo in a molar ratio of 1:1 to 6:1, with the oxidation state of Mo being 4+, 5+, or 6+.

[0083] More specifically, the NiMo-based alloy particles include Ni6Mo, Ni4Mo, Ni3Mo, or NiMo, and one or more of these can be used as a mixture of two or more. Even more specifically, the NiMo-based alloy particles may be a Ni3Mo alloy containing Ni and Mo in a molar ratio of 3:1, with the oxidation state of Mo being 4+, 5+, or 6+.

[0084] The NiMo-based alloy particles can be produced by a powder method, specifically a manufacturing method that includes the step of coprecipitation of a Ni precursor and a Mo precursor under alkaline conditions, followed by heat treatment of the resulting product.

[0085] As the Ni precursor, carbonates, nitrates, sulfates, acetates, hydroxides, chlorides, or hydrates containing Ni can be used. A specific example is nickel(II) chloride hexahydrate (NiCl2·6H2O). As the Mo precursor, carbonates, nitrates, sulfates, acetates, hydroxides, or chlorides containing Mo can be used. A specific example is MoCl5.

[0086] The mixing ratio of the Ni precursor and the Mo precursor can be appropriately determined according to the molar ratio of the elements in the alloy to be produced.

[0087] Furthermore, the coprecipitation reaction between the Ni precursor and the Mo precursor is carried out under alkaline conditions. For this purpose, one or more basic substances such as sodium hydroxide (NaOH), sodium carbonate (Na2CO3), lithium hydroxide (LiOH), or potassium hydroxide (KOH) may be added. The basic substances can be added in an amount that maintains a pH range suitable for the coprecipitation reaction to occur, specifically, a pH of 11 to 12.

[0088] Furthermore, the basic substance may be added in the form of a solution dissolved in water.

[0089] Furthermore, the coprecipitation reaction between the Ni precursor and the Mo precursor may be carried out in a solvent. In this case, ultrapure water (DI water) can be used as the solvent.

[0090] Specifically, a first solution is prepared by mixing a Ni precursor and a Mo precursor, and a second solution of a basic substance is prepared by dissolving a basic substance in water. Then, water is placed in a separate reactor, and the first and second solutions are added to it to cause a coprecipitation reaction. After the coprecipitation reaction between the Ni precursor and the Mo precursor, the reaction product is formed in the form of a precipitate.

[0091] After separation, the resulting reaction products are heat-treated at 300-500°C or 350-450°C in a mixed gas atmosphere of hydrogen and an inert gas.

[0092] The reaction products are reduced by the aforementioned heat treatment. Furthermore, the degree of alloying and the size of the alloy particles can be adjusted by controlling the heat treatment temperature. In this invention, by performing heat treatment under the aforementioned temperature conditions, NiMo-based alloy particles that satisfy the aforementioned molar ratio conditions, oxidation state conditions, and consequently, particle size conditions can be produced.

[0093] Furthermore, during the heat treatment, hydrogen may be present in a total volume of 10 to 25% of the mixed gas. In addition, nitrogen, argon (Ar), etc., can be used as the inert gas. More specifically, the heat treatment may be carried out in an H2 / N2 atmosphere in which hydrogen is present in a total volume of 10% of the mixed gas of hydrogen and nitrogen.

[0094] When manufactured using the aforementioned manufacturing method, the resulting product is obtained in particulate form and has a relatively smaller average particle diameter and a larger specific surface area compared to NiMo-based alloys manufactured by conventional methods such as electroplating or atomic deposition.

[0095] Specifically, the NiMo-based alloy particles have a BET specific surface area of ​​30 to 100 m². 2 / g, more specifically, 35-70m 2 It is / g.

[0096] In this invention, the BET specific surface area of ​​NiMo-based alloy particles can be measured using the BET (Brunauer-Emmett-Teller) method with a Micromeritics Tristar II 3020 instrument. The specific measurement method and conditions are described in the following experimental example.

[0097] Furthermore, the NiMo-based alloy particles are porous particles having multiple pores.

[0098] Specifically, the NiMo-based alloy particles have an average pore size of 5-20 nm, more specifically 9-16 nm, and a pore volume of 0.1-0.5 cm³ within the alloy particles. 3 / g, more specifically 0.12-0.2cm 3 It is / g.

[0099] On the other hand, the average pore size and pore volume of the NiMo-based alloy particles can be calculated from the amount of adsorbed nitrogen gas measured by the BET method, and the specific measurement method and conditions will be explained in the following experimental example.

[0100] Generally, NiMo alloys have a structure in which Mo is located on the Ni surface, and the higher the Mo content on the Ni surface, the higher the catalytic activity when used as a reduction catalyst in an anion exchange membrane water electrolysis system. However, in the case of NiMo alloys manufactured by conventional plating or vapor deposition methods, the Ni particle size is large, resulting in a small surface area, and consequently, a low Mo content on the Ni surface. In contrast, the alloy particles of the present invention manufactured by the above manufacturing method have a smaller Ni particle size compared to conventional alloys, resulting in a relatively larger specific surface area of ​​Ni, and consequently, a much larger amount of Mo can be present on the surface. As a result, when Mo is lost due to contact with an alkaline aqueous solution, the surface area of ​​Ni becomes larger, and consequently, superior catalytic activity can be observed.

[0101] On the other hand, binders that can be used when manufacturing the slurry for forming the preliminary reduction electrode include PTFE (Polytetrafluoroethylene), PFSA (perfluorosulfonic acid), anion exchange resin, or cation exchange resin, and one or more of these can be used.

[0102] The binder can be used in amounts of 20 to 50 parts by weight per 100 parts by weight of NiMo-based alloy particles.

[0103] Furthermore, when manufacturing the slurry for forming the preliminary reduction electrode, water or alcohol-based solvents such as isopropyl alcohol, propyl alcohol, or ethanol can be used as the solvent.

[0104] The slurry for forming the preliminary reduction electrode is applied onto a release film, dried, and then separated to produce the preliminary reduction electrode. The preliminary reduction electrode used in the water electrolysis system of the present invention consists only of a catalyst layer containing NiMo-based alloy particles and typically does not include an electrode substrate for supporting the catalyst layer.

[0105] On the other hand, in the case of an oxidation electrode, it contains an oxidation catalyst as described earlier.

[0106] The oxidation electrode can be manufactured by a conventional method for manufacturing oxidation electrodes. Specifically, it may be manufactured by a method that includes the steps of mixing an oxidation catalyst with a binder and a solvent to produce an oxidation electrode forming slurry, applying the oxidation electrode forming slurry containing the oxidation catalyst, binder and solvent onto a release film, drying it, and then separating it from the release film, or by a method that includes the steps of applying, plating or vapor-depositing an oxidation catalyst onto an electrode substrate.

[0107] Next, step 2 is the step of manufacturing a pre-membrane-electrode assembly by interposing an anion exchange membrane between the pre-reduction electrode and the oxidation electrode manufactured in step 1.

[0108] Specifically, the pre-film-electrode assembly can be manufactured by interposing an anion exchange membrane between the oxidizing electrode and the pre-reduction electrode so that the anion exchange membrane and the catalyst layer of each electrode are in contact, and then bonding them by applying heat and pressure. At this time, the bonding process using heat and pressure may be carried out by conventional methods.

[0109] Furthermore, if the manufactured pre-film-electrode assembly further includes a gasket, an additional step of joining the gasket to the manufactured assembly can be performed after the heat and pressure bonding process.

[0110] On the other hand, the release film used during the manufacture of the oxidizing electrode and the pre-reducing electrode may be separated after the completion of the bonding process.

[0111] On the other hand, the anion exchange membrane is as described above.

[0112] Furthermore, if the anion exchange membrane water electrolysis system includes multiple membrane electrode assemblies, the system may further include a step of manufacturing a stack by repeating the manufacturing process of the membrane-electrode assemblies two or more times, stacking the manufactured multiple membrane-electrode assemblies, and fastening them together by applying pressure.

[0113] Furthermore, if the stack further includes a porous transport layer and a separation plate along with the membrane-electrode assembly, the process may further include the step of manufacturing the stack by sequentially positioning the porous transport layer and the separation plate on the electrode surface side of the membrane-electrode assembly that does not come into contact with the anion exchange membrane, and then fastening them together by applying pressure.

[0114] Next, step 3 is the step of supplying an alkaline aqueous solution to the preliminary membrane-electrode assembly manufactured in step 2 to activate it.

[0115] The alkaline aqueous solution may be supplied to at least one of the pre-reduction electrode and the oxidizing electrode of the pre-film-electrode assembly.

[0116] As explained above, the alkaline aqueous solution can be supplied by an alkaline circulation device connected to the pre-film-electrode assembly, and thus the manufacturing method according to the present invention may further include a step of connecting an alkaline circulation device to the pre-film-electrode assembly after the step of manufacturing the pre-film-electrode assembly in step 2.

[0117] As an example, the process may further include, after the step of manufacturing the pre-film-electrode assembly, a step of connecting an alkaline aqueous solution circulation device to the oxidizing electrode of the pre-film-electrode assembly, in which case the alkaline aqueous solution may be supplied from the alkaline aqueous solution circulation device to the oxidizing electrode of the pre-film-electrode assembly.

[0118] As another example, after the manufacture of the pre-film-electrode assembly, the process may further include connecting an alkaline aqueous solution circulation device for the pre-reduction electrode and an alkaline circulation device for the oxidation electrode to the pre-reduction electrode and oxidation electrode of the pre-film-electrode assembly, respectively. At this time, the alkaline aqueous solution may be supplied to the pre-reduction electrode and oxidation electrode of the pre-film-electrode assembly from the alkaline aqueous solution circulation device for the pre-reduction electrode and the alkaline circulation device for the oxidation electrode, respectively.

[0119] As yet another example, the process may further include providing an alkaline circulation device after the manufacture of the pre-film-electrode assembly so that both the pre-reduction electrode and the oxidation electrode of the pre-film-electrode assembly are connected, in which case an alkaline aqueous solution may be supplied from the alkaline circulation device to the pre-reduction electrode and the oxidation electrode of the pre-film-electrode assembly.

[0120] In this invention, since the preliminary reduction electrode becomes a reduction electrode after activation, the alkaline aqueous solution circulation device for the preliminary reduction electrode connected to the preliminary reduction electrode is named the alkaline circulation device for the activated reduction electrode.

[0121] The aforementioned alkaline aqueous solution is as described above, and more specifically, it may be an aqueous potassium hydroxide solution with a concentration of 0.1 to 1 M.

[0122] The aforementioned activation process alters the molar ratio of Ni to Mo and the oxidation state of Mo in the NiMo alloy particles. The activation conditions during the activation process, specifically the current and time, affect the performance mechanism of the NiMo alloy described earlier. Therefore, in this invention, we identified the composition of a NiMo alloy that exhibits excellent performance and found and optimized the activation conditions that can realize such an alloy composition.

[0123] Specifically, the activation is 25-200 mA / cm². 2 This may be done by applying a current at a current density of 50-60°C and maintaining it for 90-360 minutes. More specifically, 50-100 mA / cm². 2This may be done by applying a current at a current density and maintaining it at 50-60°C for 300-360 minutes.

[0124] When activation is performed under the aforementioned conditions, a NiMo-based alloy catalyst that satisfies the molar ratio and oxidation state conditions described earlier can be produced, resulting in excellent water electrolysis performance.

[0125] Specifically, the molar ratio of Ni to Mo in NiMo alloy particles before activation is 1:1 to 6:1 (Ni:Mo), but during activation, Mo is lost, and the molar ratio of Ni to Mo in the NiMo alloy catalyst after activation becomes 6:1 to 101:1.

[0126] Furthermore, the oxidation state of Mo in NiMo alloy particles before activation is 4+, 5+, or 6+, but after activation it becomes 5+ or 6+. This is because the oxidation state of Mo is changed during activation through the mechanism described earlier.

[0127] Furthermore, due to the leaching of Mo during activation, a Ni layer is formed on the surface of the activated alloy catalyst and on the surface of the reducing electrode containing it.

[0128] Furthermore, the manufacturing method of the present invention may further include a cell performance confirmation step to confirm the performance of the anion exchange membrane water electrolysis system after activation.

[0129] Specifically, the cell performance verification step may be performed by maintaining the voltage in 0.05V increments from 1.45V to 1.9V for 10 seconds and measuring the current density for each interval.

[0130] The aforementioned cell performance verification step is for verifying the performance of the anion exchange membrane water electrolysis system and does not affect the activation results or cell performance.

[0131] The anion exchange membrane water electrolysis system manufactured by the above manufacturing method exhibits excellent water electrolysis performance, as well as improved durability and efficiency.

[0132] According to another embodiment of the present invention, an activation method capable of improving the performance of an anion exchange membrane water electrolysis system is provided.

[0133] Specifically, the activation method of the anion exchange membrane water electrolysis system includes a preliminary reduction electrode, an oxidation electrode, and an anion exchange membrane interposed between the preliminary reduction electrode and the oxidation electrode. The preliminary reduction electrode contains Ni and Mo in a molar ratio of 1:1 to 6:1, and contains NiMo-based alloy particles in which the oxidation number of Mo is 4+, 5+, or 6+. For the preliminary anion exchange membrane water electrolysis system, an alkaline aqueous solution is supplied, and a current is applied at a current density of 25 to 200 mA / cm 2 and maintained at 50 to 60 °C for 90 to 360 minutes to activate the preliminary reduction electrode.

[0134] The details of the preliminary anion exchange membrane water electrolysis system, the alkaline aqueous solution and its injection method, and the activation process are as described above.

[0135] Further, as a result of the activation of the preliminary reduction electrode, a reduction electrode is manufactured. The reduction electrode contains a NiMo-based alloy catalyst in which the molar ratio of Ni and Mo is 6:1 to 101:1, and the oxidation number of Mo is 5+ or 6+.

[0136] Hereinafter, preferred examples are presented for the understanding of the invention. However, the following examples are merely for illustrating the invention and do not limit the invention thereto.

Example

[0137] <Production of NiMo-based alloy particles> Production Example 1 NiCl2·6H2O and MoCl5 were dissolved in 20 ml of DI water so that the total content was 15 mmol to prepare a first solution. At this time, NiCl2·6H2O and MoCl5 were used so that the molar ratio of Ni:Mo was 1:1.

[0138] Separately, a second solution was prepared by dissolving 34.2 mmol of NaOH solution and 10.7 mmol of Na2CO3 in 20 ml of DI water.

[0139] 40 ml of DI water was placed in a vial, and the first and second solutions were added drop by drop while stirring. The mixing was carried out at room temperature (23 ± 2°C), and the pH of the mixture was maintained at 8.5 or below.

[0140] The mixed solution was stirred and reacted for 24 hours, and the resulting metal precipitate was obtained by centrifugation. The obtained metal precipitate was washed three times with water and ethanol and dried overnight in a convection oven at 50°C.

[0141] 300 mg of the dried result was reduced at 400°C for 1 hour in a 10% H2 / N2 atmosphere to produce NiMo alloy particles.

[0142] Manufacturing Example 2 Ni3Mo alloy particles were produced in the same manner as in Production Example 1, except that NiCl2·6H2O and MoCl5 were used in the production of the first solution in a Ni:Mo molar ratio of 3:1.

[0143] Manufacturing Example 3 Ni4Mo alloy particles were produced in the same manner as in Production Example 1, except that NiCl2·6H2O and MoCl5 were used in the production of the first solution so that the molar ratio of Ni:Mo was 4:1.

[0144] Manufacturing Example 4 Ni6Mo alloy particles were produced in the same manner as in Production Example 1, except that when preparing the first solution, NiCl2·6H2O and MoCl5 were used so that the molar ratio of Ni:Mo was 6:1.

[0145] <Manufacturing of water electrolysis systems> Example 1 An anion exchange membrane water electrolysis system was manufactured using the NiMo alloy particles produced in the above manufacturing example 1.

[0146] In detail, the manufacturing process followed the sequence of electrode manufacturing, membrane-electrode assembly manufacturing, KOH solution feeding system configuration, and activation.

[0147] Electrode manufacturing stage In the above-mentioned Production Example 1, NiMo alloy particles and binder were dispersed in a solvent, and then ultrasonic waves were applied for 30 minutes. Subsequently, the mixture was dispersed at a concentration of 1 or more using a ball mill to produce a slurry for forming a preliminary reduction electrode. At this time, the NiMo alloy particles and binder were used in a weight ratio of 1:0.2, and a 60% by weight PTFE (Polytetrafluoroethylene) aqueous dispersion was used as the binder. In addition, a mixed solvent of water and IPA (isopropyl alcohol) in a weight ratio of 5:5 was used as the solvent, and the solvent was used so that the solid content in the slurry for forming the preliminary reduction electrode was 20% by weight.

[0148] After drying the prepared slurry for forming the preliminary reduction electrode, the NiMo loading amount was 1.0 mg / cm³. 2 The mixture was applied to the release film using a bar coater as described above, and dried in an 80°C convection oven for 1 hour to produce a preliminary reduction electrode. XRF analysis revealed that the NiMo loading amount was 1.0 mg / cm³. 2 I checked to see if that was all.

[0149] An oxidation electrode was manufactured using the same method as described above, except that NiFe-layered double hydroxide (NiFe LDH) was used as a catalyst.

[0150] Membrane-electrode assembly manufacturing stage It was manufactured by bonding electrodes to an anion exchange membrane using the CCM (catalyst coated membrane) method.

[0151] After cutting the pre-reduction electrode and oxidation electrode manufactured in the electrode manufacturing stage into 3cm x 3cm pieces, Sustainion's Sustainion is placed between the pre-reduction electrode and the oxidation electrode.TM A pre-film-electrode assembly was fabricated by roll pressing at 130°C, 30 MPa pressure, and a speed of 0.1 m / min with an X37-50 grade RT anion exchange membrane as an intermediary. Subsequently, the release film was removed from the pre-reduction electrode and oxidation electrode. A 200 μm thick sub-gasket was bonded to the fabricated pre-film-electrode assembly to prevent cell leakage and facilitate handling.

[0152] Activation stage A lower end plate made of SUS (Steel Use Stainless) material was prepared, and on it, a Ni material separator plate for the oxide electrode, a 300 μm thick nickel foam as a porous transport layer (PTL) for the oxide electrode, and the manufactured pre-film electrode assembly were stacked so that the oxide electrode was in contact with the porous transport layer. On the reduction electrode side of the pre-film electrode assembly, a 250 μm thick carbon paper as a porous transport layer for the reduction electrode, a Ni material separator plate for the reduction electrode, and a SUS material upper end plate were positioned in order, and the stack was manufactured by fastening them together with a torque of 7 Nm.

[0153] A pre-anion exchange membrane water electrolysis system was fabricated using a dual-feeding method, where two KOH tanks were prepared as alkaline aqueous solution circulation devices and connected to the oxidation electrode and reduction electrode of the stack, respectively, to supply KOH to the oxidation electrode and reduction electrode. In this case, a 1M KOH aqueous solution was used as the alkaline aqueous solution.

[0154] KOH was supplied to the fabricated pre-anion exchange membrane water electrolysis system via dual feeding. The KOH aqueous solution was heated to 50°C and circulated at 10 cc / min. When the pre-anion exchange membrane water electrolysis system reached 50°C, a power supply was used to supply 50 mA / cm² to the system. 2After activating the cells by applying a current density for 6 hours, the cell performance was confirmed by measuring the current density in each interval while maintaining the voltage from 1.45V to 1.9V in 0.05V increments for 10 seconds using a power supply, thereby fabricating an anion exchange membrane water electrolysis system.

[0155] Examples 2-4 An anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the alloy particles manufactured in Manufacturing Examples 2 to 4 were used as the alloy particles.

[0156] Experimental Example 1 The BET specific surface area, average pore size, and average pore volume of the alloy particles produced in the above production examples 1 to 4 were measured using the following method.

[0157] Using the Brunauer-Emmett-Teller (BET) method, nitrogen gas was adsorbed onto the alloy particles produced in Production Examples 1-4 at liquid nitrogen temperature (77K) using Micromeritics Tristar II 3020. The amount of adsorbed nitrogen gas was then measured, and the specific surface area, pore volume, and pore size were calculated. The measurement results are shown in Table 1 and Figures 6A-6D below.

[0158] Figures 6A to 6D are graphs showing the BET analysis results for NiMo-based alloy particles of manufacturing examples 1, 2, 3, and 4, respectively.

[0159] [Table 1]

[0160] The experimental results showed that the NiMo-based alloy particles produced in manufacturing examples 1-4 had a BET specific surface area of ​​37-66 m². 2 At a density of 1g, the pore size was 9–16 nm, and compared to alloys produced by conventional vapor deposition or plating methods, it exhibited increased pore size and volume along with a larger BET specific surface area.

[0161] Experimental Example 2 Linear sweep voltammetry (LSV) was used to evaluate the change in the activity of hydrogen evolution reactions in NiMo-based alloys depending on the molar ratio of Ni to Mo.

[0162] LSV was performed using a 3-electrode cell with a CH Instruments CHE760E Bipotentiostat.

[0163] A catalyst slurry for the working electrode was prepared by mixing 10 mg of NiMo-based alloy particles, 1 ml of deionized water, 1.5 ml of 2-propanol, and 60 μl of 5 wt% Nafion solution. In this preparation, the NiMo-based alloy particles used were those produced in Production Examples 1-4. 10 μl of the prepared catalyst slurry was then applied to a glassy carbon rotating disk electrode (RDE) at a concentration of 0.2 mg / cm³. 2 The sample was loaded with the specified amount, and the LSV was measured using a 1M KOH solution with a Reversible Hydrogen Electrode (RHE) at 0.15V to -0.3V.

[0164] For comparison, the loading amount was also set to 0.04 mg / cm³ for 40 wt% Pt / C, which is used as a conventional catalyst for oxidation electrodes. 2 and 0.2 mg / cm³ 2 The activity changes for the hydrogen evolution reaction were evaluated in the same manner as described above, except for the following changes:

[0165] Furthermore, the initial oxidation state of Mo in the NiMo-based alloys of manufacturing examples 1 to 4 used in this experiment was confirmed by X-ray photoelectron spectroscopy (XPS).

[0166] Specifically, a Thermo Scientific K-alpha X-ray photoelectron spectrometer from Thermo Fisher Scientific was used to measure the composition of Ni3Mo alloy particles in a preliminary anion exchange membrane water electrolysis system, and the composition of the electrode surface in the anion exchange membrane water electrolysis system. To correct for the binding energy, the C 1s peak was set to 284.6 eV as the reference.

[0167] The measurement results are shown in Figures 7 and 8.

[0168] Figure 7 is a graph showing the results of evaluating the change in activity for hydrogen evolution reactions in NiMo alloys according to the molar ratio of Ni and Mo, as evaluated by linear sweep voltammetry (LSV), and Figure 8 is a graph showing the results of analyzing the initial oxidation state of Mo in NiMo alloys of production examples 1 to 4 using XPS.

[0169] Experimental results showed that the best catalytic activity was observed when the ratio of Ni to Mo in NiMo alloy particles was 3:1 to 4:1, and it was confirmed that the oxidation states of Mo at this time were 4+, 5+, and 6+.

[0170] Experimental Example 3 To confirm the leaching of Mo from NiMo-based alloys in an alkaline atmosphere, an anion exchange membrane water electrolysis system was fabricated using Ni3Mo alloy particles produced in Production Example 2, and the change in the molar ratio of Ni to Mo in the alloy before and after activation was evaluated.

[0171] Specifically, ten preliminary anion exchange membrane water electrolysis systems were manufactured in the same manner as in Example 1, except that Ni3Mo alloy particles manufactured in Manufacturing Example 2 were used as the NiMo-based alloy particles (Sample no. 1-10). The NiMo content in the manufactured preliminary anion exchange membrane water electrolysis systems, and the Ni and Mo content in the alloy were measured, respectively.

[0172] A 1M KOH solution at 50°C is circulated through each of the aforementioned pre-manufactured anion exchange membrane water electrolysis systems, at a rate of 25 mA / cm². 2 After activation by maintaining the current for 6 hours, the cell performance was confirmed by measuring the current density in each interval while maintaining the voltage from 1.45 to 1.9V in 0.05V increments for 10 seconds using a power supply, thereby manufacturing an anion exchange membrane water electrolysis system.

[0173] The NiMo alloy catalyst content and the Ni and Mo content in the alloy were measured for the manufactured anion exchange membrane water electrolysis system.

[0174] The NiMo content, as well as the Ni and Mo content in the alloy, were measured by X-ray fluorescence analysis (XRF).

[0175] Specifically, an Olympus VANTA S XRF instrument was used. Elemental analysis involved irradiating samples with 0-40 keV X-rays, and then analyzing the resulting peaks to identify the substances. Additionally, the X-ray irradiation time was maintained for 10 seconds, and calibration curves were drawn from the resulting peaks to analyze the content. The software built into the XRF instrument was used to generate these calibration curves.

[0176] The results are shown in Table 2 below.

[0177] [Table 2]

[0178] The experimental results confirmed that the loss of Mo increased after activation. Furthermore, it was confirmed that this altered the molar ratio of Ni to Mo in the NiMo alloy.

[0179] Furthermore, the reason for the aforementioned Mo outflow was investigated through thermodynamic calculations.

[0180] Table 3 below shows the leaching energy of Mo in NiMo-based alloy catalysts.

[0181] [Table 3]

[0182] As shown in Table 3 above, Ni 24When calculating the energy required for the leakage of one Mo atom at a time from a Mo8 alloy, it was found that the process always proceeds in a direction that leads to stabilization. Furthermore, computational chemistry revealed that NiMo-based alloys are stable when all the Mo present on the surface leaks out in an alkaline atmosphere.

[0183] Ni 24 The adsorption energies of H2O, MoO2, and H2O / MoO2 clusters on the surface of a Mo8 alloy were calculated, and the results showed that the leached Mo exists in the form of H2O / MoO2 after adsorption with water.

[0184] Furthermore, by calculating the adsorption energy of the hydrogen intermediate H* at the adsorption site, it was found that the hydrogen intermediate becomes more stable when adsorbed on the Ni site side rather than the Mo site side. Therefore, it can be predicted that clusters of MoO2 and H2O are adsorbed on the Ni surface, and after water splitting, hydrogen moves to the Ni surface to produce hydrogen.

[0185] From the above results, it can be seen that the hydrogen generation reaction mechanism of Ni-Mo alloys in an alkaline environment is as follows: all Mo leaches out from the Ni-Mo alloy surface, the leached Mo forms Mo oxide, which is then re-adsorbed onto the bare Ni surface in the form of H2O / Mo oxide, and thereafter, the dissociation reaction of water and the adsorption of hydrogen intermediate H* at the Ni site (dual active site) occur, and H2 is generated by the Heyrovsky or Tafel reaction.

[0186] Therefore, a NiMo alloy structure that is stable and highly active in an alkaline environment must consist of a surface made of Ni, achieved by selectively dissolving only the surface Mo. Furthermore, the dissolved Mo must be in the form of MoO2 Mo oxide, forming clusters with H2O and adsorbed onto the Ni surface. In this case, it was confirmed that the molar ratio of Ni to Mo is between 6:1 and 10¹:1.

[0187] Experimental Example 4 The change in the oxidation state of Mo in NiMo-based alloys before and after activation was evaluated.

[0188] Specifically, a preliminary anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that the Ni3Mo alloy particles manufactured in Manufacturing Example 2 were used as the NiMo-based alloy particles. The oxidation state of Mo in the Ni3Mo alloy particles in the manufactured preliminary anion exchange membrane water electrolysis system was measured.

[0189] The aforementioned pre-anion exchange membrane water electrolysis system is circulated with a 1M KOH solution at 50°C at a rate of 50 mA / cm². 2 After activation by maintaining the current for 6 hours, the cell performance was confirmed by measuring the current density in each interval while maintaining the voltage from 1.45 to 1.9V in 0.05V increments for 10 seconds using a power supply, thereby fabricating an anion exchange membrane water electrolysis system. The oxidation state of Mo in the alloy catalyst in the fabricated anion exchange membrane water electrolysis system was measured.

[0190] The oxidation state of Mo was measured by X-ray photoelectron spectroscopy (XPS), using the same measurement method and conditions as in Experimental Example 2. The results are shown in Figure 9.

[0191] Figure 9 is a graph showing the results of XPS analysis of the change in the oxidation state of Mo in Ni3Mo alloy before and after activation.

[0192] The experimental results showed that the oxidation states of Mo in the Ni3Mo alloy before activation were 4+, 5+, and 6+, but after activation they were 5+ and 6+. From this, it was confirmed that a change in the oxidation state of Mo in NiMo alloys occurs in an alkaline atmosphere.

[0193] Experimental Example 5 The effect of activation methods on the performance of an anion exchange membrane water electrolysis system was evaluated.

[0194] Specifically, except that the Ni3Mo alloy particles produced in Production Example 2 were used as the NiMo-based alloy particles, a preliminary anion exchange membrane water electrolysis system was produced in the same manner as in Example 1. Then, while injecting an alkaline aqueous solution into the produced preliminary anion exchange membrane water electrolysis system, activation was performed using two methods: one in which the applied voltage was increased and decreased as in the conventional method (hereinafter referred to as the "Comparative Example"), and the other in which a current was applied while maintaining a constant current density as in the present invention (hereinafter referred to as the "Example").

[0195] (1) Activation method 1 (Comparative example A) A 1M KOH solution at 60°C was circulated through the prepared pre-anion exchange membrane water electrolysis system. The voltage was increased from 1.45 to 1.9V in 0.05V increments, maintained for 5 seconds, and then decreased from 1.9 to 1.45V in 0.05V increments, maintained for 5 seconds. During this process, the number of activation cycles due to the voltage increase and decrease was fixed at 20 to maintain the current density.

[0196] (2) Activation Method 2 (Example A) The aforementioned pre-fabricated anion exchange membrane water electrolysis system is circulated with a 1M KOH solution at 60°C, at a rate of 100 mA / cm². 2 Activation was performed by maintaining the current for 6 hours.

[0197] After activation was completed using the method described above, the cell performance of each anion exchange membrane water electrolysis system was confirmed by maintaining the voltage from 1.45V to 1.9V in 0.05V increments for 10 seconds using a power supply and measuring the current density for each interval. During the confirmation of cell performance, the amount of current change due to voltage control was observed, and the results are shown in Figures 10 and 11.

[0198] Figure 10 is a graph showing the results of observing the change in current due to voltage control in an anion exchange membrane water electrolysis system activated by increasing and decreasing the applied voltage (Comparative Example A), and Figure 11 is a graph showing the results of observing the change in current due to voltage control in an anion exchange membrane water electrolysis system activated by applying a current at a constant current density and maintaining it for a certain period of time (Example A).

[0199] The experimental results showed that in the conventional activation method (Comparative Example A), where the applied voltage was increased and decreased, the loss of Mo accelerated when the voltage was changed, resulting in a sharp decrease in water electrolysis performance. In contrast, 100 mA / cm 2 In the activation method (Example A), which involves applying a current at a given current density and maintaining it for 6 hours, it was confirmed that the performance remained constant even after repeating the voltage change more than 10 times, because Mo flows out in the initial stages of activation and is then re-deposited onto the Ni surface.

[0200] Experimental Example 6 The effect of activation methods on the amount of Mo leaching in an anion exchange membrane water electrolysis system was evaluated.

[0201] (1) Activation method 1 (Comparative example B) Except for using the Ni3Mo alloy particles produced in Production Example 2 as the NiMo-based alloy particles, a preliminary anion exchange membrane water electrolysis system was produced in the same manner as in Example 1. Then, a 1M KOH solution at 60°C was circulated through the produced preliminary anion exchange membrane water electrolysis system, and the voltage was increased from 1.45 to 1.9V in 0.05V increments while maintaining it for 5 seconds, and then decreased from 1.9 to 1.45V in 0.05V increments while maintaining it for 5 seconds. At this time, the number of cycles was fixed so that the current density was maintained.

[0202] Subsequently, after activation, the cell performance of each anion exchange membrane water electrolysis system was confirmed by using a power supply to maintain the voltage from 1.45V to 1.9V in 0.05V increments for 10 seconds, and measuring the current density for each interval, thereby manufacturing the anion exchange membrane water electrolysis system.

[0203] (2) Activation method 2 (Example B) Except for using the Ni3Mo alloy particles produced in Production Example 2 as the NiMo-based alloy particles, a preliminary anion exchange membrane water electrolysis system is produced in the same manner as in Example 1. Then, a 1M KOH solution at 60°C is circulated through the produced preliminary anion exchange membrane water electrolysis system at 50 mA / cm². 2 Activation was performed by maintaining the current for 6 hours. Subsequently, the cell performance was confirmed by using a power supply to maintain the voltage from 1.45V to 1.9V in 0.05V increments for 10 seconds, and measuring the current density for each interval, thereby manufacturing an anion exchange membrane water electrolysis system.

[0204] The content of NiMo alloy and Mo in the pre-activation anion exchange membrane water electrolysis system, and the content of NiMo alloy and Mo remaining in the electrodes of the activated anion exchange membrane water electrolysis system, were measured by X-ray fluorescence analysis (XRF).

[0205] At this time, X-ray fluorescence analysis (XRF) and content measurement were performed in the same manner as in Experimental Example 3.

[0206] The experimental results showed that the initial Mo content in the NiMo alloy before activation was 0.75 mg / cm³. 2 (catalytic reaction area 5 cm²) 2 ) When activated using activation method 1 (Comparative Example B), the Mo content after activation is 0.07 mg / cm³. 2 Approximately 9% remained. In contrast, when activated using activation method 2 (Example B), the initial Mo content was 0.75 mg / cm³. 2 0.18 mg / cm³ after activation 2 Approximately 24% remained.

[0207] From this, we confirmed that the activation method of the present invention is advantageous in reducing the amount of Mo leaching, and as a result, it can improve the lifespan characteristics of the water electrolysis system.

[0208] Experimental Example 7 To evaluate the effect of activation current conditions on the performance mechanism of NiMo-based alloys, the current density was set to 25 mA / cm². 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2 The cells were activated by changing each of the following parameters, and their performance was evaluated.

[0209] Specifically, a preliminary anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that Ni3Mo alloy particles from Manufacturing Example 2 were used. A 1M KOH solution at 50°C was circulated through the manufactured preliminary anion exchange membrane water electrolysis system, and a current density of 25 mA / cm² was maintained. 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2 The cells were activated by applying current for 6 hours under the specified conditions. Subsequently, the cell performance was confirmed by measuring the current density in each interval while maintaining the voltage from 1.45V to 2.5V in 0.05V increments for 10 seconds using a power supply, thereby fabricating an anion exchange membrane water electrolysis system.

[0210] For comparison, a preliminary anion exchange membrane water electrolysis system was manufactured using a 40 wt Pt / C catalyst as the reducing electrode catalyst, in the same manner as in Example 1. The manufactured preliminary anion exchange membrane water electrolysis system was activated by circulating a 1 M KOH solution at 50°C and increasing the voltage from 1.45 to 1.9 V in 0.05 V increments while maintaining for 5 seconds, and then decreasing it from 1.9 to 1.45 V in 0.05 V increments while maintaining for 5 seconds. The number of cycles was fixed to maintain the current density. Thereafter, the cell performance was confirmed in the same manner as described above, and an anion exchange membrane water electrolysis system was manufactured.

[0211] The voltage change corresponding to the current density was measured using linear sweep voltammetry (LSV) on the fabricated anion exchange membrane water electrolysis system, and a polarization curve was obtained as a result.

[0212] Specifically, the voltage change corresponding to the current density was measured for each of the anion exchange membrane water electrolysis systems manufactured as described above, using a CH760E Bipotentiostat instrument manufactured by CH Instruments, under LSV conditions. The results are shown in Figure 12.

[0213] Furthermore, the durability of the fabricated anion exchange membrane water electrolysis system was evaluated using chronoamperometry.

[0214] Specifically, a power supply of 1 A / cm² was used to provide each of the anion exchange membrane water electrolysis systems manufactured as described above. 2 The voltage was measured while maintaining the current density. Maintaining a stable voltage without fluctuations was considered a sign of high durability, while an increase in voltage was considered a sign of low durability. The results are shown in Figure 13.

[0215] Figure 12 shows a current density of 25 mA / cm². 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2 The graph shows the polarization evaluation results for anion exchange membrane water electrolysis systems activated under the following conditions. Figure 13 shows the results for a current density of 25 mA / cm². 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2 This graph shows the durability evaluation results for anion exchange membrane water electrolysis systems activated under the specified conditions.

[0216] Experimental results showed a current density of 25-200 mA / cm². 2 When activated within this range, it exhibits excellent performance characteristics, particularly in terms of current density of 50 mA / cm². 2 When activated, it was confirmed to exhibit superior performance and durability compared to platinum.

[0217] On the other hand, the reason for the aforementioned experimental results can be understood by the pourbaix diagram.

[0218] Figure 14 is a phase diagram of Mo according to pH, disclosed in the literature "Anatolyevich, Pavel. 'The Revised Pourbaix Diagram for Molybdenum.' HMo2.10:3."

[0219] As shown in Figure 14, in an alkaline atmosphere and a specific current interval, Mo is MoO4 2- Alternatively, it can be seen that it exists in the form of MoO2. Also, under conditions of pH 12 or higher, Mo is MoO4. 2- It dissolves and leaches out in this form. However, looking at line 26, we can confirm that it can exist in the MoO2 form in a specific voltage range between pH 9 and 12. This experiment and computational chemistry show that activation in a specific current range allows Mo to exist in the MoO2 form, which corresponds to 50 mA / cm². 2 If it is activated, we were able to predict that it is likely to exist in MoO2.

[0220] Additionally, the effect of the current conditions during activation on the leaching of Mo from NiMo-based alloys in an alkaline atmosphere was evaluated.

[0221] For this reason, the current density is set to 25 mA / cm². 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2 The amount of remaining Mo in the anion exchange membrane water electrolysis systems, which were activated by changing the respective properties, was measured by X-ray fluorescence analysis (XRF) in the same manner as in Experimental Example 3.

[0222] The results are shown in Figure 15.

[0223] Figure 15 shows a current density of 25 mA / cm². 2 , 50mA / cm 2 , 100mA / cm 2 and 200mA / cm 2This graph shows the results of analyzing the remaining amount of Mo in anion exchange membrane water electrolysis systems activated under the specified conditions, using X-ray fluorescence (XRF) analysis.

[0224] Experimental results showed a current density of 50 mA / cm². 2 When activated, the largest amount of Mo remained in the cathode. From this, it can be predicted that the Mo that leached out due to activation will be re-adsorbed onto the Ni surface.

[0225] Experimental Example 8 To evaluate the effect of activation time on the performance development mechanism of NiMo-based alloys, the cells were activated for 90 minutes, 180 minutes, and 360 minutes, and their performance was evaluated.

[0226] Specifically, a preliminary anion exchange membrane water electrolysis system was manufactured in the same manner as in Example 1, except that Ni3Mo alloy particles from Manufacturing Example 2 were used. A 1M KOH solution at 50°C was circulated through the manufactured preliminary anion exchange membrane water electrolysis system, and a current density of 50 mA / cm² was maintained. 2 The cells were activated by applying current for 90 minutes, 3 hours, and 6 hours under the specified conditions. Subsequently, the cell performance was confirmed by measuring the current density for each interval while maintaining the voltage from 1.45V to 1.9V in 0.05V increments for 10 seconds using a power supply, and an anion exchange membrane water electrolysis system was manufactured.

[0227] For comparison, a preliminary anion exchange membrane water electrolysis system was manufactured using a 40 wt Pt / C catalyst as the reducing electrode catalyst, in the same manner as in Example 1. The manufactured preliminary anion exchange membrane water electrolysis system was activated by circulating a 1 M KOH solution at 50°C and increasing the voltage from 1.45 to 1.9 V in 0.05 V increments while maintaining for 5 seconds, and then decreasing it from 1.9 to 1.45 V in 0.05 V increments while maintaining for 5 seconds. At this time, the number of cycles was fixed at 10 to maintain the current density. Thereafter, the cell performance was confirmed by measuring the current density for each interval while maintaining the voltage from 1.45 V to 1.9 V in 0.05 V increments for 10 seconds using a power supply, thereby manufacturing the anion exchange membrane water electrolysis system.

[0228] The anion exchange membrane water electrolysis system manufactured as described above was subjected to a chronoamperometry method at 1 A / cm². 2 The voltage values ​​were measured while maintaining the specified conditions. The results are shown in Figure 16.

[0229] Figure 16 is a graph showing the results of an evaluation of the effect of activation time on the performance development of NiMo-based alloys.

[0230] Experimental results showed that when the activation time was 180 minutes or longer, it exhibited performance superior to platinum, and when the activation time was 360 minutes or longer, it became stable.

[0231] Experimental Example 9 We evaluated the change in Mo loss due to the circulation method of alkaline aqueous solution in an anion exchange membrane water electrolysis system.

[0232] Using the Ni3Mo alloy particles produced in Production Example 2, a preliminary anion exchange membrane water electrolysis system including a both-feeding alkaline aqueous solution circulation device as shown in Figure 4 and a preliminary anion exchange membrane water electrolysis system including an anode-feeding alkaline aqueous solution circulation device as shown in Figure 5 were produced. The NiMo content in the produced preliminary anion exchange membrane water electrolysis systems, and the Ni and Mo content in the alloy were measured, respectively.

[0233] Next, a 1M KOH solution at 60°C is circulated through the aforementioned pre-anion exchange membrane water electrolysis system at 25 mA / cm². 2 An anion exchange membrane water electrolysis system was fabricated by activating the system by applying a current and maintaining it for 6 hours, and then checking the cell performance by measuring the current density in each interval while maintaining the voltage from 1.45 to 1.9V in 0.05V increments for 10 seconds using a power supply. The content of NiMo alloy catalyst and the content of Ni and Mo in the alloy were measured in the fabricated anion exchange membrane water electrolysis system.

[0234] The content of NiMo and the contents of Ni and Mo in the alloy were measured by X-ray fluorescence analysis (XRF) in the same manner as in Experimental Example 3. The results are shown in Table 4 below.

[0235]

Table 4

[0236] As a result of the experiment, the Anode feeding method, which supplies the KOH solution only to the oxidation electrode side, showed a lower Mo loss rate than the Both feeding method, which supplies the KOH solution simultaneously.

[0237] In the case of the Both feeding method, the dissolution of Mo caused by the direct contact of the NiMo catalyst with the KOH solution and the dissolution of Mo that is anionized and moves to the anode occur simultaneously. In contrast, Anode feeding shows a lower dissolution rate than Both feeding because the NiMo catalyst does not come into direct contact with KOH.

[0238] Experimental Example 10 The influence of the circulation method of the alkaline aqueous solution in the anion exchange membrane water electrolysis system on the performance of the water electrolysis system was evaluated.

[0239] Using the Ni3Mo alloy particles produced in Production Example 2, a preliminary anion exchange membrane water electrolysis system including an alkaline aqueous solution circulation device with a boss feeding (both feeding) method as shown in FIG. 4 and a preliminary anion exchange membrane water electrolysis system including an alkaline aqueous solution circulation device with a dual feeding method as shown in FIG. 6 were each produced.

[0240] Next, for the preliminary anion exchange membrane water electrolysis system, a 1 M KOH solution was circulated at 60°C, and 25 mA / cm 2The cells were activated by maintaining a current for 6 hours, and the cell performance was confirmed by measuring the current density in each interval while maintaining the voltage from 1.45 to 1.9V in 0.05V increments for 10 seconds using a power supply, thereby manufacturing an anion exchange membrane water electrolysis system.

[0241] For each of the anion exchange membrane water electrolysis systems manufactured as described above, the voltage change corresponding to the current density was measured using linear sweep voltammetry (LSV), and a polarization curve was obtained as a result.

[0242] Specifically, for each of the anion exchange membrane water electrolysis systems manufactured as described above, the voltage change corresponding to the current density was measured using a CH760E Bipotentiostat (manufactured by CH Instruments) under LSV conditions.

[0243] Furthermore, the durability of the fabricated anion exchange membrane water electrolysis system was evaluated using chronoamperometry.

[0244] Specifically, a power supply of 1 A / cm² was used to provide each of the anion exchange membrane water electrolysis systems manufactured as described above. 2 The voltage was measured while maintaining the current density. A stable voltage was considered indicative of high durability, while an increase in voltage was considered indicative of low durability. The results are shown in Figures 17 and 18, respectively.

[0245] Figure 17 is a graph showing the polarization evaluation results of an anion exchange membrane water electrolysis system using an alkaline aqueous solution circulation method, and Figure 18 is a graph showing the durability evaluation results of an anion exchange membrane water electrolysis system.

[0246] The experimental results showed that the both-feeding method, which uses separate tanks to supply the KOH aqueous solution, was able to produce hydrogen at a lower voltage than the dual-feeding method, which uses a single tank to supply the KOH aqueous solution. In other words, it can be confirmed that the system efficiency is higher when the KOH aqueous solution is configured separately as an anode and a cathode.

Claims

1. The steps include manufacturing the preliminary reduction electrode and the oxidation electrode, respectively. The steps include: manufacturing a pre-film-electrode assembly by interposing an anion exchange membrane between the pre-reduction electrode and the oxidation electrode; The step includes supplying an alkaline aqueous solution to the pre-film-electrode assembly to activate the pre-reduction electrode, The aforementioned pre-reduction electrode contains NiMo alloy particles in which the molar ratio of Ni to Mo is 1:1 to 6:1 and the oxidation state of Mo is 4+, 5+, or 6+. The aforementioned activation is 25-200 mA / cm². ２ This is done by applying a current at a current density and maintaining it at 50-60°C for 90-360 minutes. A method for manufacturing an anion exchange membrane water electrolysis system.

2. The aforementioned activation is 50-100 mA / cm². ２ This is done by applying a current at a current density and maintaining it at 50-60°C for 300-360 minutes. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

3. The alkaline aqueous solution is supplied to at least one of the pre-reduction electrode and the oxidizing electrode of the pre-film-electrode assembly. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

4. The process further includes, after the step of manufacturing the pre-film-electrode assembly, connecting an alkaline aqueous solution circulation device to the oxidizing electrode of the pre-film-electrode assembly, The alkaline aqueous solution is supplied from the alkaline aqueous solution circulation device to the oxidizing electrode of the pre-film-electrode assembly. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

5. After manufacturing the pre-film-electrode assembly, the process further includes connecting an alkaline aqueous solution circulation device for the pre-reduction electrode and an alkaline circulation device for the oxidation electrode to the pre-reduction electrode and oxidation electrode of the pre-film-electrode assembly, respectively. Alkaline aqueous solution is supplied to the pre-reduction electrode and the oxidation electrode of the pre-film-electrode assembly from the alkaline aqueous solution circulation device for the pre-reduction electrode and the alkaline aqueous solution circulation device for the oxidation electrode, respectively. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

6. The process further includes the step of providing an alkali circulation device so that both the preliminary reduction electrode and the oxidation electrode of the preliminary film-electrode assembly are connected after the manufacturing of the preliminary film-electrode assembly, An alkaline aqueous solution is supplied from the alkaline circulation device to the pre-reduction electrode and the oxidizing electrode of the pre-film-electrode assembly. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

7. The aforementioned alkaline aqueous solution is a potassium hydroxide aqueous solution with a concentration of 0.1 to 1 M. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

8. The NiMo alloy particles have a molar ratio of Ni to Mo of 3:1, and the oxidation state of Mo is 4+, 5+, or 6+. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

9. The NiMo alloy particles are produced by a manufacturing method that includes the step of coprecipitation of a Ni precursor and a Mo precursor under alkaline conditions, followed by heat treatment of the resulting product. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

10. The aforementioned pre-reduction electrode is manufactured by a manufacturing method that includes the steps of applying a slurry for forming a pre-reduction electrode, containing the NiMo-based alloy particles, a binder, and a solvent, onto a release film, drying it, and then separating it from the release film. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

11. The binder is one or more selected from the group consisting of polytetrafluoroethylene, perfluorosulfonic acid, anion exchange resin, and cation exchange resin. A method for producing an anion exchange membrane water electrolysis system according to claim 10.

12. As a result of the aforementioned activation, a reduction electrode is manufactured. The reduction electrode includes a NiMo-based alloy catalyst in which the molar ratio of Ni to Mo is 6:1 to 101:1 and the oxidation state of Mo is 5+ or 6+. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

13. The NiMo-based alloy catalyst includes a Ni layer on its surface. A method for producing an anion exchange membrane water electrolysis system according to claim 12.

14. The aforementioned oxidation electrode is It is manufactured by a manufacturing method that includes the steps of applying an oxide electrode forming slurry containing an oxidation catalyst, a binder, and a solvent onto a release film, drying it, and then separating it from the release film, or Manufactured by a manufacturing method that includes the step of applying, plating, or vapor-depositing an oxidation catalyst onto an electrode substrate. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

15. The oxidation catalyst comprises one or more selected from the group consisting of Ni, NiCoFe, Ir, and NiFe-layered bihydroxylated oxides. A method for producing an anion exchange membrane water electrolysis system according to claim 14.

16. The step further includes confirming cell performance by maintaining the voltage from 1.45 to 1.9V in 0.05V increments for 10 seconds after the activation and measuring the current density for each interval. A method for producing an anion exchange membrane water electrolysis system according to claim 1.

17. Manufactured by the manufacturing method described in claim 1, The device comprises a reducing electrode containing a particulate NiMo-based alloy catalyst, an oxidizing electrode, an anion exchange membrane interposed between the reducing electrode and the oxidizing electrode, and an alkaline aqueous solution. The NiMo-based alloy catalyst contains Ni and Mo in a molar ratio of 6:1 to 101:1, and the oxidation state of Mo is 5+ or 6+. Anion exchange membrane water electrolysis system.

18. The aforementioned anion exchange membrane water electrolysis system is The system includes an anode-feeding type alkaline aqueous solution circulation device located connected to the oxidizing electrode and supplying an alkaline aqueous solution to the oxidizing electrode; a boss-feeding type alkaline aqueous solution circulation device located connected to both the oxidizing electrode and the reducing electrode and supplying an alkaline aqueous solution to both the oxidizing electrode and the reducing electrode; or a dual-feeding type alkaline aqueous solution circulation device for the oxidizing electrode, comprising an alkaline aqueous solution circulation device for the oxidizing electrode and an alkaline aqueous solution circulation device for the reducing electrode, respectively, located connected to the oxidizing electrode and the reducing electrode. The anion exchange membrane water electrolysis system according to claim 17.

19. A pre-anion exchange membrane water electrolysis system comprising a pre-reduction electrode, an oxidation electrode, and an anion exchange membrane interposed between the pre-reduction electrode and the oxidation electrode, wherein the pre-reduction electrode contains Ni and Mo in a molar ratio of 1:1 to 6:1 and contains NiMo alloy particles in which the oxidation state of Mo is 4+, 5+, or 6+, A solution of alkaline water is supplied, and the current is 25-200 mA / cm². ２ The process includes a step of applying a current at a current density and maintaining it at 50-60°C for 90-360 minutes to activate the pre-reduction electrode. A method for activating an anion exchange membrane water electrolysis system.

20. As a result of the aforementioned activation, a reduction electrode is manufactured. The reduction electrode includes a NiMo-based alloy catalyst in which the molar ratio of Ni to Mo is 6:1 to 101:1 and the oxidation state of Mo is 5+ or 6+. A method for activating an anion exchange membrane water electrolysis system according to claim 19.

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