Electrode for water electrolysis, membrane-electrode assembly comprising same, and water electrolysis cell

Abstract

The present invention relates to: an electrode for water electrolysis, the electrode comprising a protective metal matrix and noble metal catalyst particles dispersed in the protective metal matrix, wherein the arithmetic average (Ra) of the surface roughness is 100 nm or less; a method for manufacturing the same; and a membrane-electrode assembly and a water electrolysis cell that comprise the electrode for water electrolysis. The electrode for water electrolysis according to the present invention can exhibit excellent water electrolysis performance and durability.

Description

Electrode for water electrolysis, membrane-electrode assembly including the same, and water electrolysis cell

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0157070 filed November 7, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to an electrode for water electrolysis that can enhance electrical connectivity between catalyst particles and provide excellent durability through the protective layer by forming a protective layer on a plurality of precious metal catalyst particles coated on a flat substrate using an atomic film deposition method, a membrane-electrode assembly including the same, and a water electrolysis cell.

[0005] Hydrogen has the advantages of being suitable for storage and transportation and being eco-friendly, leading to various recent attempts to utilize it as an energy source. While various methods for producing hydrogen are known, the method of producing hydrogen through water electrolysis has the advantage of being environmentally friendly as it does not generate harmful byproducts.

[0006] Representative methods of water electrolysis include alkaline electrolysis (AEC) and polymer electrolyte membrane (PEM). Among these, alkaline electrolysis is a method that electrolyzes water using an alkaline electrolyte and is the most commercialized technology among various electrolysis methods. Alkaline electrolysis has the advantages of relatively low process operating costs, a simple production structure making it suitable for large-scale hydrogen production, and excellent durability. However, alkaline electrolysis has limitations, such as the need to continuously replenish the electrolyte consumed during the electrolysis process, corrosion problems caused by alkaline components, and low current density efficiency. On the other hand, polymer electrolyte membrane electrolysis utilizes polymer electrolyte membranes as the electrolyte, primarily employing cation exchange membranes. Polymer electrolyte membrane electrolysis offers the advantage of high energy efficiency because it allows operation at high current densities using precious metal catalysts, and the purity of the produced hydrogen is very high as it does not require an electrolyte component. Therefore, various studies on water electrolysis using polymer electrolyte membranes are currently being conducted.

[0007] Meanwhile, water electrolysis using polymer electrolyte membranes involves oxygen evolution at the anode and hydrogen evolution at the cathode, and hydrogen production efficiency is determined by the efficiency of both reactions. Pt / C catalysts are known to exhibit high efficiency for hydrogen evolution, while precious metal catalysts such as iridium are known to exhibit high efficiency for oxygen evolution. However, precious metal catalysts like iridium suffer from a problem where their durability decreases as the electrochemical reaction progresses, and since they are also expensive, various efforts are being made to develop catalysts for oxygen evolution and anodes for water electrolysis that can minimize iridium usage while ensuring durability. For example, there are prior studies that aim to secure the durability of catalyst particles while reducing the iridium loading per unit area by applying doping or coating films to iridium catalyst particles. However, applying doping and coating to particles in this manner is difficult to implement in actual mass production due to the high complexity of the process, and it does not provide sufficient improvements in terms of activity and durability. Therefore, it is necessary to develop a new structure of electrode for water electrolysis that can minimize the use of the aforementioned iridium while simultaneously improving performance.

[0008]

[0009] Prior art literature

[0010] (Patent Document 1) KR 10-2023-0040742 A

[0011] The present invention aims to solve the above-mentioned problem by first coating precious metal catalyst particles onto a flat substrate and then introducing a protective layer having a constant arithmetic mean roughness value thereon using atomic film deposition, thereby providing an electrode for water electrolysis that is easy to manufacture and has excellent durability and electrochemical properties, a membrane-electrode assembly including the same, and a water electrolysis cell.

[0012] To solve the above-mentioned problem, the present invention provides an electrode for water electrolysis, a method for manufacturing the same, a membrane-electrode assembly including the electrode for water electrolysis, and a water electrolysis cell.

[0013] Specifically, (1) the present invention provides an electrode for water electrolysis comprising a protective metal matrix and precious metal catalyst particles dispersed within the protective metal matrix, wherein the arithmetic mean roughness (Ra) measured over any region of the electrode surface is 100 nm or less.

[0014] (2) The present invention provides an electrode for water electrolysis in which, in (1) above, the protective metal matrix comprises a protective metal oxide.

[0015] (3) The present invention provides an electrode for water electrolysis in which, in (1) or (2), the protective metal is one or more selected from the group consisting of Ti, Ru, Co, Zr and Al.

[0016] (4) The present invention provides an electrode for water electrolysis in which, in any one of (1) to (3), the precious metal catalyst particles include precious metal oxide particles.

[0017] (5) The present invention provides an electrode for water electrolysis in which, in any one of (1) to (4), the precious metal is one or more selected from the group consisting of Ir, Pt, Ru and Pd.

[0018] (6) The present invention provides an electrode for water electrolysis characterized in that, in any one of (1) to (5), the standard deviation of the arithmetic mean roughness is 10 nm or less.

[0019] (7) In any one of (1) to (6) of the present invention, the content of precious metal elements per unit area of ​​the electrode for water electrolysis is 0.1 mg / cm² 2 Above and 0.8 mg / cm² 2 The present invention provides an electrode for water electrolysis with a lower value.

[0020] (8) The present invention provides a water electrolysis electrode in any one of (1) to (7), wherein the water electrolysis electrode is an anode.

[0021] (9) The present invention provides a method for manufacturing an electrode for water electrolysis comprising the steps of: coating precious metal catalyst particles on a substrate (S1); and forming a protective metal layer on a coating layer containing precious metal catalyst particles using an atomic film deposition method (S2).

[0022] (10) The present invention provides a method for manufacturing an electrode for water electrolysis in which the thickness of the protective metal layer is 2 nm or less, in accordance with (9).

[0023] (11) The present invention provides a membrane-electrode assembly comprising an electrolyte membrane and an electrode for water electrolysis according to any one of (1) to (8).

[0024] (12) The present invention provides a membrane-electrode assembly in which the electrolyte membrane is a cation exchange membrane, in accordance with (11).

[0025] (13) The present invention provides a membrane-electrode assembly characterized in that, in (11) or (12), the electrode for water electrolysis is formed on one side of the electrolyte membrane, and further includes a negative electrode for water electrolysis on the opposite side from the side where the electrode for water electrolysis is formed.

[0026] (14) The present invention provides a water electrolysis cell comprising a membrane-electrode assembly according to any one of (11) to (13).

[0027] The electrode for water electrolysis of the present invention has excellent electrical connectivity between catalyst particles and satisfies a certain range of arithmetic mean roughness of the electrode surface, thereby allowing the active sites of the catalyst to be more exposed, which in turn enables excellent water electrolysis performance.

[0028] In addition, the electrode for water electrolysis of the present invention may have excellent durability due to a protective layer formed using an atomic film deposition method.

[0029] Figure 1 is the result of measuring the roughness of the electrode surface according to Examples 1 and 2 and Comparative Example 2 of the present invention using an AFM apparatus.

[0030] The present invention will be described in more detail below.

[0031] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0032]

[0033] Electrode for water electrolysis

[0034] The present invention provides an electrode for water electrolysis comprising a protective metal matrix and precious metal catalyst particles dispersed within the protective metal matrix, characterized in that the arithmetic mean roughness (Ra) measured over any region of the electrode surface is 100 nm or less.

[0035]

[0036] In the electrode for water electrolysis according to the present invention, the protective metal matrix serves to protect precious metal catalyst particles. The precious metal catalyst particles may be dispersed on the protective metal matrix, and multiple precious metal catalyst particles within the protective metal matrix may be electrically connected. More specifically, the protective metal matrix may be formed continuously or discontinuously, and may be formed continuously in most areas. Forming the protective metal matrix continuously means that the protective metal matrix is ​​formed as a single connected area, while forming it discontinuously means that the protective metal matrix is ​​formed as multiple separated areas. In the case of an area where the protective metal matrix is ​​formed continuously in this manner, the electrical connection of the precious metal catalyst particles described above may be further strengthened. In the above protective metal matrix, the proportion of the continuously formed protective metal matrix may be 50 area% or more, 60 area% or more, 70 area% or more, 80 area% or more, 85 area% or more, 90 area% or more, 95 area% or more, 97 area% or more, or 98 area% or more.

[0037] The above protective metal matrix may include a protective metal oxide, and the protective metal may be one or more selected from the group consisting of Ti, Ru, Co, Zr, and Al, and particularly preferably may be Ti. The above-mentioned protective metals have the advantage of having excellent durability in a water electrolysis environment so that they are not easily damaged and do not degrade the electrical properties of the electrode itself.

[0038]

[0039] In the electrode for water electrolysis according to the present invention, the precious metal catalyst particles are components that directly exhibit activity for the water electrolysis reaction, and the water electrolysis reaction can proceed through a reaction using the precious metal catalyst particles. The precious metal catalyst particles may particularly exhibit activity for the oxygen evolution reaction, and more specifically, the precious metal catalyst particles may include precious metal oxide particles. In addition, the precious metal may be one or more selected from the group consisting of Ir, Pt, Ru, and Pd, and preferably may be Ir. The precious metal components are components known to have excellent catalytic activity for the water electrolysis reaction, and when the precious metal catalyst particles include the precious metal components, the performance of the water electrolysis electrode may be excellent.

[0040] The above precious metal catalyst particles may have an average particle size of 2 nm or more and 20 nm or less, and preferably may be 2 nm or more, 3 nm or more, 4 nm or more, 5 nm or more, 7 nm or more, 8 nm or more, or 9 nm or more, and 20 nm or less, 19 nm or less, 18 nm or less, 17 nm or less, 15 nm or less, 13 nm or less, 12 nm or less, or 11 nm or less. In addition, the above precious metal catalyst particles have a bulk density of 9 g / cm³ 3 Above and 20g / cm² 3 It may be less than or equal to, preferably 9 g / cm³ 3 Above, 10g / cm² 3 ≥ or 11 g / cm³ 3 Ideally, and 20g / cm² 3 Below, 18g / cm³ 3 Below, 17g / cm³ 3 Below, 16g / cm³ 3 Below, 15g / cm³ 3 Below, 14g / cm² 3 Below, 13g / cm² 3 Less than or equal to 12 g / cm³ 3It may be less than or equal to. In addition, the above precious metal catalyst particles have a specific surface area of ​​30 m² 2 / g or more and 120m 2 It may be less than / g, preferably 30m 2 / g or more, 33m 2 / g or more, 35m 2 / g or more, 37m 2 / g or more, 40m 2 / g or more, 43m 2 / g or more or 45m 2 / g or more and 120m 2 / g or less, 115m 2 / g or less, 110m 2 / g or less, 105m 2 / g or less, 100m 2 / g or less, 95m 2 / g or less, 90m 2 / g or less, 85m 2 / g or less, 80m 2 / g or less, 77m 2 / g or less, 75m 2 / g or less, 73m 2 / g or less, 70m 2 / g or less, 67m 2 / g or less, 65m 2 / g or less, 63m 2 / g or less or 60m 2 It may be less than / g. If the precious metal catalyst particles satisfy the above-described conditions, the performance of the electrode for water electrolysis can be maximized while minimizing the amount of precious metal used.

[0041]

[0042] Meanwhile, in the electrode for water electrolysis provided by the present invention, the arithmetic mean roughness (Ra) measured over any region of the electrode surface may be 100 nm or less, preferably 95 nm or less, 90 nm or less, 85 nm or less, or 80 nm or less, and at the same time may be 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, 50 nm or more, 55 nm or more, 60 nm or more, 65 nm or more, or 70 nm or more. In addition, the standard deviation of the arithmetic mean roughness may be 10 nm or less, and preferably 9 nm or less, 8 nm or less, 7.5 nm or less, 7 nm or less, 6.5 nm or less, 6 nm or less, 5.5 nm or less, 5 nm or less, 4.5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, 1.5 nm or less, or 1 nm or less. The electrode for water electrolysis of the present invention has an uneven surface structure as the active sites of the precious metal catalyst particles are partially exposed, but as the precious metal catalyst particles are dispersed within a protective metal matrix, the arithmetic mean roughness may be small, such as 100 nm or less. Meanwhile, the arithmetic mean roughness may be measured using an AFM device for any area of ​​the electrode surface, and the area of ​​the arbitrary area may be, for example, 5 μm x 5 μm. The fact that the arithmetic mean roughness measured for any of the above-mentioned regions is 100 nm means that, substantially speaking, the value of the arithmetic mean roughness measured for any region of the electrode surface for water electrolysis provided by the present invention is 100 nm or less. That is, it means that the arithmetic mean roughness value measured for all regions of the electrode surface is 100 nm or less. Meanwhile, the standard deviation of the arithmetic mean roughness may be a standard deviation value obtained for three or more regions.

[0043] The electrode for water electrolysis according to the present invention is manufactured by first coating precious metal catalyst particles onto a substrate and then introducing a protective layer thereon using atomic layer deposition, rather than by individually introducing and coating a protective layer onto the precious metal catalyst particles. If a protective layer were applied to the precious metal catalyst particles individually, the size of the particles themselves would increase, and the surface of the electrode coated with these particles would exhibit increased non-uniformity. On the other hand, as in the present invention, if a protective layer is introduced after the precious metal catalyst particles have been coated first, the protective layer can be formed to surround the coated precious metal catalyst particles in a form similar to a protective metal matrix, thereby improving the surface uniformity of the electrode. When the electrode has a low arithmetic mean roughness in this manner, resistance to corrosion or oxidation is high, which can increase the durability of the electrode. Furthermore, by reducing the contact resistance between the electrode and the electrolyte, energy loss during the electrolysis process can be minimized.

[0044]

[0045] In the electrode for water electrolysis of the present invention, the content of a precious metal element per unit area of ​​the electrode for water electrolysis is 0.1 mg / cm² 2 Above and 0.8 mg / cm² 2 It may be less than or equal to, preferably 0.1 mg / cm² 2 Above, 0.15 mg / cm² 2 ≥ or 0.2 mg / cm² 2 Above, and 0.8 mg / cm² 2 Below, 0.7 mg / cm² 2 Below, 0.6 mg / cm² 2 Less than 0.5 mg / cm² 2 Less than or equal to 0.4 mg / cm² 2 The following may apply. The electrode for water electrolysis according to the present invention has a relatively low content of precious metal elements per unit area and can achieve excellent performance even with a low content of precious metal elements.

[0046]

[0047] The electrode for water electrolysis of the present invention may be an anode. During the water electrolysis reaction, an oxygen evolution reaction is performed at the anode, and the electrode for water electrolysis of the present invention may have excellent activity for the oxygen evolution reaction.

[0048]

[0049] Method for manufacturing electrodes for water electrolysis

[0050] The present invention provides a method for manufacturing an electrode for water electrolysis as described above.

[0051]

[0052] More specifically, the present invention provides a method for manufacturing an electrode for water electrolysis comprising the step (S1) of coating precious metal catalyst particles on a substrate and the step (S2) of forming a protective metal layer on a coating layer containing the precious metal catalyst particles using an atomic film deposition method.

[0053]

[0054] The above step S1 is a step of primarily coating precious metal catalyst particles onto at least one surface of a substrate. The coating in this step may be performed using a precious metal catalyst composition containing precious metal catalyst particles. The precious metal catalyst composition may be prepared by mixing precious metal catalyst particles with an ionomer in an appropriate ratio, and the precious metal catalyst particles may be coated by applying the precious metal catalyst composition to at least one surface of the substrate and then drying it.

[0055] The above coating may be performed using methods known in the art, and as an example, the above coating may be performed using a bar coater. The temperature at which the above coating is performed may be 20°C or higher and 60°C or lower, and preferably 20°C or higher, 25°C or higher, 30°C or higher, or 35°C or higher, and 60°C or lower, 55°C or lower, 50°C or lower, or 45°C or lower.

[0056] The above drying may be performed using equipment such as an oven, and the temperature at which the drying is performed may be 60°C or higher and 100°C or lower, preferably 60°C or higher, 65°C or higher, 70°C or higher, or 75°C or higher, and 100°C or lower, 95°C or lower, 90°C or lower, or 85°C or lower.

[0057] The substrate used in this step may be an electrolyte membrane or a transfer substrate included in the membrane-electrode assembly described later. If the substrate is a transfer substrate, a membrane-electrode assembly can be manufactured by forming an electrode on the transfer substrate and then transferring the electrode to a separate electrolyte membrane. As the transfer substrate, one or more substrates selected from the group consisting of polytetrafluoroethylene (PTFE) film, polyimide (PI) film, ethylene tetrafluoroethylene (ETFE) film, and Teflon (PFA) film may be used. These types of substrates have the advantage of allowing easy transfer of an electrode formed on the substrate, as well as easy manufacturing of the electrode on the substrate.

[0058]

[0059] Meanwhile, the precious metal catalyst particles coated in this step may be the same as those described above.

[0060]

[0061] The above protective metal layer may correspond to the protective metal matrix described earlier. If a protective metal layer is formed on top of a particulate precious metal catalyst using atomic layer deposition, an electrode can be manufactured in which precious metal catalyst particles are dispersed within the protective metal matrix.

[0062] The atomic film deposition method for forming the above-mentioned protective metal layer comprises a process comprising: 1) injecting a protective metal precursor into a chamber using a carrier gas; 2) injecting only the carrier gas into the chamber to remove residual reactants after the precursor injection is completed; 3) injecting water or ozone to form a protective metal oxide; and 4) injecting the carrier gas to remove residual reactants after the reaction is completed. By controlling the number of repetitions of the cycle, the thickness of the protective metal layer can be controlled. The thickness of the protective metal layer may be 2 nm or less, and preferably 0.05 nm to 1 nm. If the thickness of the protective metal layer is too thick, the precious metal catalyst particles may not be sufficiently exposed, which may instead lead to a decrease in the performance of the electrode for water electrolysis. Meanwhile, the thickness of the protective metal layer can be measured through a TEM image, and more specifically, after obtaining a cross-sectional image of the protective metal layer using a Transmission Electron Microscope (TEM), the thickness of the protective metal layer can be directly measured from the cross-sectional image.

[0063]

[0064] Membrane-electrode assembly and water electrolysis cell

[0065] The present invention provides a membrane-electrode assembly comprising the electrode for water electrolysis described above. The membrane-electrode assembly may comprise an electrolyte membrane and an electrode for water electrolysis, and the electrode for water electrolysis may be formed on one side of the electrolyte membrane. Meanwhile, in the membrane-electrode assembly, an electrode for a hydrogen generation reaction (a negative electrode for water electrolysis) may be formed on the side where the electrode for water electrolysis of the present invention is not formed.

[0066] Meanwhile, the above electrolyte membrane may be any electrolyte membrane used in a water electrolysis cell without any special limitations, and more specifically, the above electrolyte membrane may be a cation exchange membrane.

[0067]

[0068] The present invention includes a water electrolysis cell comprising the above membrane-electrode assembly.

[0069] The above-described water electrolysis cell may comprise a membrane-electrode assembly including an anode for water electrolysis, a cathode for water electrolysis, and an electrolyte membrane interposed between the anode and the cathode, a gas diffusion layer formed on both sides of the membrane-electrode assembly, and a separator formed on the outer side of the gas diffusion layer.

[0070] The above gas diffusion layer may be a porous diffusion layer that allows the formed gas to move smoothly, and the above separator may serve to protect the water electrolysis cell while distinguishing it from other cells.

[0071]

[0072] Hereinafter, the present invention will be described in more detail through examples and experimental examples to specifically explain the invention, but the present invention is not limited by these examples and experimental examples. The embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the invention to those with average knowledge in the art.

[0073]

[0074] Example 1

[0075] Iridium oxide (IrO2) particles, which are precious metal catalyst particles, were first coated onto a PTFE film. Specifically, a precious metal catalyst composition was prepared by mixing iridium oxide particles and the ionomer Nafion in a weight ratio of 10:1, and then the prepared precious metal catalyst composition was coated using a bar coater at 40°C with an iridium loading amount of 0.4 mg / cm² per unit area. 2 It was applied to a PTFE film. Then, the PTFE film was placed in an oven at 80°C and dried for 1 hour to coat the PTFE film with iridium oxide particles.

[0076] After that, the above PTFE film was introduced into the atomic film deposition equipment chamber, and the atomic film deposition cycle was repeated to form a titanium oxide protective layer on the area coated with iridium oxide particles.

[0077] More specifically, a titanium oxide protective layer was formed by 1) setting the temperature of the atomic film deposition equipment chamber to 120°C and loading the PTFE film, 2) injecting a titanium transition metal precursor into the chamber using a carrier gas, 3) injecting only the carrier gas into the chamber after the precursor injection is completed to remove residual reactants, 4) injecting water or ozone to form a transition metal oxide, and 5) injecting the carrier gas after the reaction is completed to remove residual reactants. The process of steps 2) to 5) was performed as one cycle, and three cycles were repeated. The thickness of the formed protective layer was confirmed to be 0.3 nm, and a membrane-electrode assembly was manufactured by transferring the electrode for water electrolysis formed on the PTFE film to the electrolyte membrane at 140°C.

[0078]

[0079] Example 2

[0080] A membrane-electrode assembly was prepared by carrying out the same procedure as in Example 1 above, except that the number of cycles was repeated 7 times. The thickness of the protective layer formed in Example 2 was confirmed to be 0.7 nm.

[0081]

[0082] Comparative Example 1

[0083] A film-electrode assembly was manufactured in the same manner as in the above example, except that the atomic film deposition process was not performed.

[0084]

[0085] Comparative Example 2

[0086] In Example 1 above, precious metal catalyst particles were first introduced into the atomic film deposition equipment chamber, and a titanium oxide protective layer was formed on the precious metal catalyst particles themselves through the same process as in Example 1. Then, the precious metal catalyst particles with the protective layer formed thereon were coated onto a PTFE film through the same process as in Example 1, and this was transferred to an electrolyte membrane to manufacture a membrane-electrode assembly.

[0087]

[0088] Experimental Example 1. Verification of surface roughness of the manufactured electrode

[0089] The surface roughness of the electrodes prepared in Examples 1 and 2 and Comparative Example 2 was verified. Specifically, roughness values ​​were measured at three points (5㎛ X 5㎛) using an Atomic Force Microscopy (AFM) system (NX-10, Park System, measurement software: SmartScan, analysis software: XEI), and the measured arithmetic mean roughness values, their mean, and standard deviation (population standard deviation) were calculated. The results are shown in Table 1 and Figure 1 below.

[0090] Example 1 Example 2 Comparative Example 2 Arithmetic mean roughness of Point 1 (nm) 78.0 66.6 10 2.5 Arithmetic mean roughness of Point 2 (nm) 78.1 49.2 12 0.6 Arithmetic mean roughness of Point 3 (nm) 76.3 61.2 11 1.9 Arithmetic mean of arithmetic mean roughness (nm) 77.5 59.0 11 1.7 Standard deviation of arithmetic mean roughness (nm) 0.8 7.3 7.4

[0091] As confirmed by the results in Table 1 and Figure 1 above, when precious metal catalyst particles are first coated and then a protective layer is formed using atomic film deposition as in the present invention, it can be seen that a uniform surface is formed with low surface roughness values ​​and a small standard deviation. On the other hand, if a protective layer is first formed on the particles and then a coating layer is formed, a non-uniform surface with high roughness values ​​is formed, as shown in the result of Comparative Example 2.

[0092]

[0093] Experimental Example 2. Cell Evaluation

[0094] Cell evaluation was performed using the membrane-electrode assemblies prepared in the above examples and comparative examples. A Pt / C catalyst was used as the negative electrode of the cell, and the negative electrode was formed on the opposite side of the membrane-electrode assemblies prepared in the examples and comparative examples. Titanium felt was used as the gas diffusion layer of the anode, and a carbon gas diffusion layer was used as the gas diffusion layer of the negative electrode. The cell evaluation condition was 3 A / cm² 2 Constant current, temperature of 80℃, water flow rate of 10–40 mL / min, and cell area of ​​4 cm 2 It was conducted for 100 hours.

[0095] 1) LSV (Linear Sweep Voltametry): Measures the current-voltage curve while varying the voltage at a constant scan rate of 10 mV / s until a specific voltage (2 V) is reached, starting from a set initial voltage (1.2 V), and 3 A / cm 2 The voltage value corresponding to was read, and the initial performance was measured.

[0096] 2) Ohmic resistance (Ω·cm) 2 @ 1.2A / cm 2 The electrochemical impedance measurement method was used. The x-intercept value of the high-frequency region in the Nyquist plot obtained by applying an AC signal from the high-frequency to low-frequency range at the voltage at which the water electrolysis electrochemical reaction begins was taken as the ohmic resistance value.

[0097] 3) Cell degradation rate: The difference between the initial cell voltage and the cell voltage after the durability evaluation was defined as the cell degradation rate (unit: mV).

[0098] The measurement results are summarized in Table 2 below.

[0099] Ir loading amount (mg / cm²) 2Initial Cell Voltage (V) Ohmic Resistance Cell Degradation Rate Example 10.4 1.9 0.1 90 Example 21.9 210.1 1 5 Comparative Example 11.8 9 20.1 21 6 6 Comparative Example 21.9 3 20.1 - 22

[0100] As summarized in Table 2 above, the electrolytic electrode of the present invention exhibited excellent initial performance, low resistance, and cell degradation rate. From this, it was confirmed that the durability of the electrolytic electrode can be improved through a protective metal matrix, and furthermore, the performance can be enhanced by strengthening the electrical connection between precious metal catalyst particles through the protective metal matrix. In particular, the electrode of the above example was superior in terms of cell degradation rate compared to Comparative Example 1 and exhibited superior catalytic performance compared to Comparative Example 2. Meanwhile, in the case of Comparative Example 2, the degradation rate showed a tendency to repeatedly decrease and increase during cell evaluation for less than 500 hours, and as a result, it was confirmed that the cell degradation rate also showed a negative value.

Claims

1. Protective metal matrix; and It includes precious metal catalyst particles dispersed within the above protective metal matrix; An electrode for water electrolysis characterized by an arithmetic mean roughness (Ra) of 100 nm or less measured over any region of the electrode surface.

2. In Paragraph 1, The above-mentioned protective metal matrix is ​​an electrode for water electrolysis comprising a protective metal oxide.

3. In Paragraph 1, The above protective metal is one or more selected from the group consisting of Ti, Ru, Co, Zr, and Al, for a water electrolysis electrode.

4. In Paragraph 1, The above-mentioned precious metal catalyst particles are an electrode for water electrolysis comprising precious metal oxide particles.

5. In Paragraph 1, The above precious metal is one or more selected from the group consisting of Ir, Pt, Ru, and Pd, for a water electrolysis electrode.

6. In Paragraph 1, An electrode for water electrolysis characterized by a standard deviation of arithmetic mean roughness of 10 nm or less.

7. In Paragraph 1, The content of precious metal elements per unit area of ​​the above-mentioned water electrolysis electrode is 0.1 mg / cm² 2 Above and 0.8 mg / cm² 2 Electrode for water electrolysis with less than 100 8. In Paragraph 1, The above-mentioned electrode for water electrolysis is an electrode for water electrolysis that is an anode.

9. A step of coating precious metal catalyst particles on a substrate (S1); and A method for manufacturing an electrode for water electrolysis comprising the step (S2) of forming a protective metal layer on a coating layer containing the above precious metal catalyst particles using an atomic film deposition method.

10. In Paragraph 9, A method for manufacturing an electrode for water electrolysis in which the thickness of the protective metal layer is 2 nm or less.

11. Electrolyte membrane; and A membrane-electrode assembly comprising: an electrode for water electrolysis according to claim 1; 12. In Paragraph 11, The above electrolyte membrane is a membrane-electrode assembly that is a cation exchange membrane.

13. In Paragraph 11, The above-mentioned electrode for water electrolysis is formed on one side of the electrolyte membrane, and A membrane-electrode assembly characterized by further including a water electrolysis cathode on a surface opposite to the surface on which the water electrolysis electrode is formed.

14. A water electrolysis cell comprising a membrane-electrode assembly according to paragraph 11.

Images