Method for preparing catalytic electrode by emulsion template method and application of catalytic electrode in electrolyzed water

Abstract

The invention provides a technical method for carrying out an electrodeposition process in a water-based emulsion and preparing a catalytic electrode, belongs to the technical field of catalytic electrode preparation, and discloses a catalytic electrode and a preparation method thereof. The preparation method of the catalytic electrode specifically comprises the following steps: mixing molybdenum disulfide dispersion liquid with a trichloromethane solution of polylactic acid to obtain Pickering emulsion; and carrying out electrochemical deposition treatment on a porous metal matrix in the Pickering emulsion-containing electrodeposition liquid, and cleaning and drying to obtain the catalytic electrode. The preparation method of the catalytic electrode is simple and reliable, industrial implementation is easy, and the prepared catalytic electrode has high catalytic activity and is suitable for being applied to electrochemical devices for hydrogen production through water electrolysis, oxygen production and the like.

Description

Technical Field

[0001] This application relates to the field of catalytic electrodes, specifically to catalytic electrodes, their preparation methods, and their application in water electrolysis. Background Technology

[0002] The total amount of fossil fuels is limited and cannot meet the world's rapidly growing energy demand. Furthermore, the consumption of fossil fuels leads to problems such as the greenhouse effect and air pollution. Therefore, developing new, environmentally friendly, and clean energy sources to replace dependence on fossil fuels has become a trend in energy technology development.

[0003] Hydrogen is an ideal clean energy source, possessing advantages such as high energy density and low pollution from combustion products. In industrial hydrogen production, a large amount of hydrogen originates from the steam reforming processes of natural gas, coal, and oil. These industrial processes generate significant pollutant emissions and additional energy consumption. Therefore, zero-carbon emission water electrolysis hydrogen production technology is of great significance for improving energy efficiency and reducing environmental pollutant emissions. However, the large-scale industrial application and promotion of water electrolysis hydrogen production are still limited by its high energy consumption and low efficiency.

[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] In a first aspect of this application, a method for preparing a catalytic electrode is proposed, comprising: mixing a molybdenum disulfide dispersion with a chloroform solution of polylactic acid to obtain a Pickering emulsion; and electrochemically depositing a porous metal substrate in an electrodeposition solution to obtain the catalytic electrode, wherein the electrochemical deposition solution includes the Pickering emulsion.

[0006] In some embodiments, the volume ratio of the molybdenum disulfide dispersion to the polylactic acid chloroform solution is (1~10):1.

[0007] In some embodiments, at least one of the following conditions is met: the particle size of molybdenum disulfide in the molybdenum disulfide dispersion is 2 μm to 5 μm; the concentration of molybdenum disulfide in the molybdenum disulfide dispersion is 10 mg / mL to 100 mg / mL; and the mass percentage of molybdenum disulfide dispersion in the electrodeposition solution is 1% to 10%.

[0008] In some embodiments, the mass concentration of polylactic acid in the chloroform solution of polylactic acid is 10 mg / mL to 100 mg / mL.

[0009] In some embodiments, the molybdenum disulfide dispersion further includes chitosan, wherein the concentration of the chitosan is 1 g / mL to 3 g / mL.

[0010] In some embodiments, the polylactic acid in the chloroform solution has a weight-average molecular weight of 5,000 to 30,000.

[0011] In some embodiments, the current density of the electrochemical deposition process is 0.2 A·cm⁻¹. -2 ~0.8A·cm -2 ; and / or, the electrochemical deposition treatment time is 0.1h to 0.7h.

[0012] In some embodiments, the porous metal substrate includes at least one of a nickel-based substrate, a copper-based substrate, and a stainless steel substrate.

[0013] In some embodiments, the method further includes: performing a surface treatment on the porous metal substrate, wherein the surface treatment solution includes at least one of sulfuric acid and deionized water.

[0014] In a second aspect of this application, a catalytic electrode is provided, which is prepared using the method for preparing a catalytic electrode proposed in this application.

[0015] The beneficial effects of the technical solution proposed in this application include at least the following: The catalytic electrodes prepared using the method described in this application exhibit excellent electrocatalytic hydrogen evolution performance in both acidic and alkaline electrolytes. The preparation process involves only solution preparation and electrochemical deposition, making it simple, environmentally friendly, and resulting in electrodes with high catalytic activity and low preparation cost. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The particle size distribution curves of molybdenum disulfide in molybdenum disulfide dispersion, molybdenum disulfide nanosheet dispersion and molybdenum disulfide-based Piccorin emulsion in Comparative Example 2, Example 1 and Comparative Example 1 are shown. Figure 2 The linear scan curve of the hydrogen evolution catalytic electrode under acidic conditions prepared in one embodiment of this application is shown. Figure 3 The linear scan curve of the hydrogen evolution catalytic electrode prepared in one embodiment of this application under alkaline conditions is shown. Figure 4 This is a scanning electron microscope (SEM) image of the surface of the catalytic electrode prepared in Example 1 of this application; Figure 5 This refers to the electrochemically active area of ​​the catalytic electrode prepared in an embodiment of this application under acidic conditions. Figure 6 This represents the electrochemically active area of ​​the catalytic electrode prepared in one embodiment of this application under alkaline conditions.

[0017] Figure 7 The polarization curve of the catalytic electrode prepared in Example 1 of this application under alkaline conditions; Figure 8 The results show the long-term stability test of the catalytic electrode prepared in Example 1 of this application under alkaline conditions. Detailed Implementation

[0018] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0020] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0021] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0022] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0024] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0025] Electrolysis of water using catalytic electrodes with high hydrogen evolution catalytic activity is an effective method to reduce the energy consumption of water electrolysis. Among the available technologies, non-precious metals have superior catalytic capabilities, but the catalytic activity of catalytic electrodes prepared with non-precious metals is relatively low. Taking two-dimensional non-precious metal catalysts as an example, their effective catalytic area is limited after being made into catalytic electrodes, resulting in their inability to fully exhibit hydrogen evolution activity.

[0026] Molybdenum disulfide is one of the representative two-dimensional non-noble metal catalysts. It has high hydrogen evolution activity. However, in the process of preparing catalytic electrodes in practical applications, there are problems such as the catalytic sites with hydrogen evolution activity being blocked due to the stacking of molybdenum disulfide sheet structure, the large size of the stacked molybdenum disulfide limiting its effective deposition in catalytic electrolysis, the introduction of additional resistance, and the resulting increase in operating voltage.

[0027] In a first aspect of this application, a method for preparing a catalytic electrode is proposed, comprising: mixing a molybdenum disulfide dispersion with a chloroform solution of polylactic acid to obtain a Pickering emulsion; and electrochemically depositing a porous metal substrate in an electrodeposition solution to obtain the catalytic electrode, wherein the electrochemical deposition solution includes the Pickering emulsion.

[0028] To address the problems existing in current processes, this application proposes a method for preparing a catalytic electrode. This method utilizes an emulsion template method to prepare a Pickering emulsion that stably disperses molybdenum disulfide, which has high hydrogen evolution activity. A porous metal substrate is placed in an electrodeposition solution containing the Pickering emulsion containing molybdenum disulfide, and electrochemical deposition is performed on the porous metal substrate to prepare the catalytic electrode.

[0029] The preparation of Pickering emulsion-dispersed molybdenum disulfide utilizes the charge repulsion and steric hindrance effect of the Pickering emulsion to promote the dispersion of molybdenum disulfide as a catalyst for the hydrogen evolution reaction, thereby exposing more catalytically active sites. For example... Figure 4 As shown, the catalytic electrode prepared by the method of this application has a hollow spherical shell structure on its surface, which has a high surface area, facilitating the full exposure of catalytically active sites on molybdenum disulfide. Pickering emulsion has a high specific surface area; using it as a template is beneficial for the uniform enrichment of elements such as nickel and phosphorus in the electrodeposition solution, allowing them to deposit on the outer surface of the emulsion droplets and transform into a solid phase, effectively increasing the electrochemically active area of ​​the prepared catalytic electrode. This not only improves the dispersibility of molybdenum disulfide in solution, reducing the impact of the decrease in the number of active sites caused by molybdenum disulfide layer stacking on the prepared catalytic electrode, but also controls the size of molybdenum disulfide. Furthermore, due to the high specific surface area of ​​molybdenum disulfide in the Pickering emulsion, the catalytic electrode prepared after electrochemical deposition has a high electrochemically active area, thus facilitating the optimization of the hydrogen evolution activity of the prepared catalytic electrode.

[0030] The catalytic electrodes prepared using the method described in this application exhibit excellent electrocatalytic hydrogen evolution performance in both acidic and alkaline electrolytes. The preparation process involves only solution preparation and electrochemical deposition, making it simple, environmentally friendly, and resulting in electrodes with high catalytic activity and low preparation cost.

[0031] In some embodiments, the volume ratio of the molybdenum disulfide dispersion to the polylactic acid solution in chloroform is (1~10):1. Therefore, the polylactic acid swollen and dispersed in chloroform can act as a better template, aiding in the dispersion of molybdenum disulfide in the solution system, controlling its size and structure, and preparing a more stable Pickering emulsion, thereby reducing the masking of active sites on molybdenum disulfide due to excessive aggregation.

[0032] In some embodiments, the particle size of molybdenum disulfide in the molybdenum disulfide dispersion is 2 μm to 5 μm. Therefore, molybdenum disulfide within the aforementioned particle size range can be dispersed relatively uniformly in the molybdenum disulfide dispersion, which is beneficial for the subsequent preparation of Pickering emulsion.

[0033] In some embodiments, the concentration of molybdenum disulfide in the molybdenum disulfide dispersion is 1 mg / mL to 10 mg / mL. This reduces the aggregation and stacking of molybdenum disulfide in the dispersion, which is beneficial for controlling the size of the molybdenum disulfide.

[0034] In some embodiments, the mass percentage of molybdenum disulfide dispersion in the electrodeposition solution is 1% to 10%. This allows the porous metal substrate to contact molybdenum disulfide relatively uniformly in the electrodeposition solution, and during the electrochemical deposition process, molybdenum disulfide can form a distribution with a large specific surface area on the porous metal substrate, effectively exposing catalytic sites and improving the catalytic performance of the prepared catalytic electrode.

[0035] In some embodiments, the mass concentration of polylactic acid in the chloroform solution is 10 mg / mL to 100 mg / mL. This facilitates the adequate dispersion of polylactic acid in chloroform at an appropriate concentration to provide an emulsion template for molybdenum disulfide dispersion.

[0036] In some embodiments, the method further includes: the molybdenum disulfide dispersion comprising chitosan, wherein the concentration of chitosan is 1 g / mL to 3 g / mL. Chitosan in Pickering emulsion can promote the distribution of molybdenum disulfide into nanoscale particles, resulting in a more uniform distribution of catalytic sites, thereby improving the catalytic activity of the prepared catalytic electrode.

[0037] In some embodiments, the weight-average molecular weight of the polylactic acid in the chloroform solution is 5000-30000. Therefore, the molecular size of the aforementioned polylactic acid in solution is suitable, which can reduce the stacking of molybdenum disulfide in the solution and is beneficial to increasing the specific surface area of ​​molybdenum disulfide on the prepared catalytic electrode surface.

[0038] In some embodiments, the current density of the electrochemical deposition process is 0.2 A·cm⁻¹. -2 ~0.8A·cm -2 ; and / or, the electrochemical deposition treatment time is 0.1 h to 0.7 h. This facilitates the deposition of a catalytic electrode with a certain binding force and a high specific surface area.

[0039] In some embodiments, the porous metal substrate includes at least one of a nickel-based substrate, a copper-based substrate, and a stainless steel substrate. Therefore, the aforementioned porous metal substrate exhibits high stability, which is beneficial for the uniform deposition of molybdenum disulfide.

[0040] In some embodiments, the electrodeposition solution comprises 0-0.2M nickel chloride, 0-2M ammonium chloride, 0-0.05M sodium hypophosphite, and 0-5 g / L sodium citrate. This allows for the deposition of a high-density, highly uniform nickel-based coating, which is beneficial for the deposition of molybdenum disulfide, which has catalytic hydrogen evolution capabilities, to prepare a catalytic electrode.

[0041] In some embodiments, the method further includes: performing a surface treatment on the porous metal substrate, wherein the surface treatment solution includes at least one of sulfuric acid and deionized water. This removes impurities from the surface of the porous metal substrate, improving the quality of the electrochemical deposition.

[0042] In a second aspect, this application proposes a catalytic electrode prepared using the method proposed in this application. The catalytic electrode prepared using the method proposed in this application exhibits high catalytic activity and, when used in the hydrogen evolution process, can improve the efficiency of hydrogen evolution from water and reduce the energy consumption for hydrogen evolution.

[0043] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0044] Example 1 Step 1: Disperse 0.2g of molybdenum disulfide powder in 20mL of water and sonicate to obtain a molybdenum disulfide dispersion. Add 4mL of a 2.0% (w / w) chitosan solution to the molybdenum disulfide dispersion, heat at 90℃ for 16h, and then centrifuge the treated molybdenum disulfide dispersion at 10000 rpm. Discard the supernatant after centrifugation to obtain a molybdenum disulfide nanosheet dispersion.

[0045] Step 2: Add 4 mL of molybdenum disulfide nanosheet dispersion to 1 mL of chloroform solution containing 0.05 g of polylactic acid. The volume ratio of molybdenum disulfide nanosheet dispersion to chloroform solution of polylactic acid is 4:1. Homogenize the mixture using a homogenizer to obtain a molybdenum disulfide-based Pickering emulsion.

[0046] Step 3: Prepare an electrodeposition solution containing 0.2 M nickel chloride, 2 M ammonium chloride, 0.05 M sodium hypophosphite, and 5 g / L sodium citrate for the preparation of nickel foam.

[0047] Step 4: Place the nickel-based metal on the cathode side of the two-electrode electrolytic cell, submerging it below the surface of the electrodeposition solution at 0.5 A·cm. -2Electrochemical deposition was performed at a current density of 30 min. The resulting foamed nickel porous metal matrix was rinsed with water and ethanol and then air-dried.

[0048] Step 5: Place the foamed nickel porous metal substrate on the cathode side of the two-electrode electrolytic cell, submerging the porous metal substrate below the surface of the electrodeposition solution. Add 5 mL of molybdenum disulfide-based Pickering emulsion to 50 mL of the electrodeposition solution and perform electrochemical deposition at 0.5 A·cm⁻¹. -2 The electrode was treated at a current density of 30 min, then rinsed with water and ethanol, and air-dried to obtain the catalytic electrode.

[0049] Example 2 Example 2 is the same as Example 1, except that the volume ratio of the molybdenum disulfide nanosheet dispersion to the polylactic acid chloroform solution is 1:1.

[0050] Example 3 Example 2 is the same as Example 1, except that the volume ratio of the molybdenum disulfide nanosheet dispersion to the polylactic acid chloroform solution is 10:1.

[0051] Comparative Example 1 Comparative Example 1 is consistent with Example 1, except that step one is different and step two is not performed. Specifically, the electrodeposition solution includes a fluidized molybdenum nanosheet dispersion.

[0052] Comparative Example 2 Comparative Example 1 is the same as Example 1, except that step one is different and step two is not performed. Specifically, the electrodeposition solution includes a molybdenum disulfide dispersion.

[0053] Test methods and results: Dynamic light scattering technique was used to characterize the exfoliation and size distribution of molybdenum disulfide materials in Example 1, Comparative Example 1, and Comparative Example 2. The results are shown below. Figure 1 Compared to untreated micron-sized molybdenum disulfide dispersions, both molybdenum disulfide nanosheet dispersions and molybdenum disulfide-based Pickering emulsions possess nanoscale dimensions, which is beneficial for the subsequent preparation of catalytic electrodes via electrodeposition.

[0054] Using the catalytic electrode prepared in the examples as the working electrode, and with iridium dioxide as the counter electrode and a silver / silver chloride electrode as the reference electrode in an acidic solution, a linear voltammetric scan was performed in a 0.5 M sulfuric acid aqueous solution. The results are as follows: Figure 2 As shown, at a current density of 10 mA·cm -2 At that time, the overpotential required for hydrogen evolution of the catalytic electrode prepared by molybdenum disulfide-based Pickering emulsion was only 91.5 mV, indicating that this electrode has excellent catalytic hydrogen and oxygen evolution activity under acidic conditions.

[0055] Using the catalytic electrode prepared in the examples as the working electrode, and with graphite as the counter electrode and a mercury / mercury oxide electrode as the reference electrode in an alkaline solution, a linear voltammetric scan was performed in a 1.0 M potassium hydroxide aqueous solution. The results are as follows: Figure 3 As shown, at a current density of 10 mA·cm -2 At that time, the overpotential required for hydrogen evolution in the molybdenum disulfide-based Pickering emulsion catalytic electrode was only 19.3 mV, indicating that the catalytic electrode of this application also has excellent catalytic hydrogen evolution activity in an alkaline environment.

[0056] In summary, the catalytic electrode of this application has the lowest overpotential required for hydrogen evolution in acidic and alkaline environments compared to the catalytic electrode prepared by molybdenum disulfide-based Pickering emulsion in Example 1. This indicates that the method of this application can effectively improve the hydrogen evolution activity of the prepared catalytic electrode.

[0057] The catalytic electrode prepared in the examples was used as the working electrode, and cyclic voltammetry was performed in acidic and alkaline solutions to calculate the electrochemical active area of ​​the electrode in these solutions. The results are as follows: Figure 5 , Figure 6 As shown, the catalytic electrode prepared by molybdenum disulfide-based Pickering emulsion in Example 1 has a large electrochemical active area in both acidic and alkaline environments, and therefore has excellent catalytic hydrogen evolution activity.

[0058] The catalytic activity of the catalytic electrode prepared in Example 1 was tested in the battery, and the polarization curves were plotted as follows: Figure 7 As shown. At a current density of 1 A·cm⁻¹ -2 At that time, the battery voltage was only 1.86 V, indicating that the prepared catalytic electrode also possesses high hydrogen evolution activity in practical applications. Subsequently, at 80 °C, 1 A·cm⁻¹... -2 A constant current test was performed at a current density, and the results are as follows: Figure 8 As shown, the voltage of the catalytic electrode remained stable at around 1.9 V within 270 h, proving that it has stable hydrogen evolution activity in practical applications.

[0059] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0060] In the description of this application, "same chemical composition" should be interpreted broadly, that is, the main components of the two have the same chemical composition, or the two have substantially the same chemical composition, but may have errors or impurities within the acceptable range that can be understood by those skilled in the art.

[0061] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0062] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a catalytic electrode using an emulsion template method, characterized in that, include: A molybdenum disulfide dispersion was mixed with a chloroform solution of polylactic acid to obtain a Pickering emulsion. The catalytic electrode is obtained by electrochemical deposition of a porous metal substrate in an electrodeposition solution, wherein the electrochemical deposition solution includes the Pickering emulsion.

2. The method according to claim 1, characterized in that, The volume ratio of the molybdenum disulfide dispersion to the polylactic acid chloroform solution is (1~10):

1.

3. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The particle size of molybdenum disulfide in the molybdenum disulfide dispersion is 2μm~5μm; The concentration of molybdenum disulfide in the molybdenum disulfide dispersion is 1 mg / mL to 10 mg / mL; The mass percentage of molybdenum disulfide dispersion in the electrodeposition solution is 1% to 10%.

4. The method according to claim 1, characterized in that, The polylactic acid in the chloroform solution has a mass concentration of 10 mg / mL to 100 mg / mL.

5. The method according to any one of claims 1 to 4, characterized in that, Also includes: The molybdenum disulfide dispersion also includes chitosan, the concentration of which is 1 g / mL to 3 g / mL.

6. The method according to any one of claims 1 to 4, characterized in that, Also includes: The polylactic acid in the chloroform solution has a weight-average molecular weight of 5000~30000.

7. The method according to any one of claims 1 to 4, characterized in that, The current density of the electrochemical deposition process is 0.2 A·cm. -2 ~0.8A·cm -2 ; and / or, The electrochemical deposition treatment time is 0.1h to 0.7h.

8. The method according to any one of claims 1 to 4, characterized in that, The porous metal matrix includes at least one of nickel-based matrix, copper-based matrix, and stainless steel matrix.

9. The method according to any one of claims 1 to 4, characterized in that, Also includes: The porous metal substrate is subjected to surface treatment, wherein the surface treatment solution includes at least one of sulfuric acid and deionized water.

10. A catalytic electrode, characterized in that, The catalytic electrode is prepared by the method described in any one of claims 1 to 9, and the catalytic electrode is applied to an electrochemical device for producing hydrogen by electrolysis of water and an electrochemical device for producing oxygen by electrolysis of water.

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