Catalyst electrode and method for manufacturing catalyst electrode

Abstract

To provide a catalyst electrode and a method for manufacturing a catalyst electrode.SOLUTION: A catalyst electrode according to an embodiment of the present disclosure includes: a metal layer; and a catalyst layer formed on the metal layer, wherein the catalyst layer includes iridium and palladium.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to catalytic electrodes and methods for making catalytic electrodes. [Background technology]

[0002] Hydrogen energy is a clean energy source and has been drawing attention as one of the promising alternative energy sources for solving the energy problem in the long term. Among the hydrogen production methods, the water electrolysis method, which uses electrical energy to separate water into hydrogen and oxygen and does not emit carbon dioxide, is attracting much attention as it is environmentally friendly and is expected to make a significant contribution to achieving carbon neutrality.

[0003] Meanwhile, water electrolysis reactions include oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), which are shown in Chemical Formula 1 below.

[0004] [C1] Oxygen evolution reaction: 2H2O→4H + +O2+4e - Hydrogen generation reaction: 4H + +4e - →2H2 Overall reaction: 2H2O → 2H2 + O2

[0005] In particular, in the water electrolysis reaction, an overpotential higher than the theoretical oxygen evolution reaction voltage is generated due to a slower reaction rate of the oxygen evolution reaction than that of the hydrogen evolution reaction. Therefore, in order to improve the performance of a water electrolysis system, it is necessary to develop a highly efficient catalyst that can reduce the reaction overpotential of the oxygen evolution reaction, which requires a large overpotential. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure can provide catalytic electrodes and methods for manufacturing catalytic electrodes with improved performance in oxygen evolution reactions. [Means for solving the problem]

[0007] A catalytic electrode according to an embodiment of the present disclosure includes a metal layer and a catalytic layer formed on the metal layer, the catalytic layer including iridium and palladium. In one embodiment, the catalytic electrode includes 0.02 to 0.8 mg / cm2 of iridium and palladium in the catalytic layer. 2 and the catalyst layer contains iridium in an amount of 0.1 to 0.8 mg / cm. 2 The palladium content can be as above.

[0008] In one embodiment, at least a portion of the iridium and palladium contained in the catalyst layer may be chemically bonded to each other.

[0009] In one embodiment, the metal layer may include one or more selected from the group consisting of metal mesh, metal foam, metal foil, metal felt, and metal fiber.

[0010] In one embodiment, the metal layer may include one or more metals selected from the group consisting of titanium, nickel, and stainless steel.

[0011] In one embodiment, the iridium and palladium can be electrochemically deposited onto the metal layer.

[0012] In one embodiment, the iridium and palladium may be in direct contact with the metal layer.

[0013] In one embodiment, the catalyst layer may be binder-free.

[0014] A method for manufacturing a catalytic electrode according to an embodiment of the present disclosure includes depositing iridium and palladium on a metal substrate.

[0015] In one embodiment, the step of depositing iridium and palladium on the metal substrate may include the steps of: placing the metal substrate in a solution containing an iridium precursor and a palladium precursor; and electrochemically depositing the iridium and palladium on the metal substrate.

[0016] In one embodiment, at least a portion of the iridium and palladium deposited on the metal substrate may be chemically bonded to each other.

[0017] In one embodiment, the step of electrochemically depositing the iridium and palladium onto the metal substrate may be performed by applying a voltage via one or more electrodes in contact with the solution.

[0018] In one embodiment, the voltage may increase at a constant rate.

[0019] In an embodiment, the method for manufacturing the catalytic electrode may further include a step of heat treating the metal substrate on which the iridium and palladium are deposited.

[0020] In an embodiment, the method for manufacturing the catalytic electrode may further include treating the metal substrate with an acid before depositing iridium and palladium on the metal substrate.

[0021] A membrane electrode assembly according to an embodiment of the present disclosure includes an electrolyte membrane, an anode located on one side of the electrolyte membrane, and a cathode located on the other side of the electrolyte membrane, and the anode may include a metal layer and a catalyst layer formed on the metal layer and including iridium and palladium. Effect of the Invention

[0022] According to the present disclosure, it is possible to provide a catalytic electrode having improved performance in an oxygen evolution reaction and a method for manufacturing the catalytic electrode. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a diagram for explaining a catalytic electrode according to an embodiment of the present disclosure. [Diagram 2] 1 is a flowchart illustrating a method for manufacturing a catalytic electrode according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a diagram for explaining an example of an electrochemical system used in a method for producing a catalytic electrode according to an embodiment of the present disclosure. [Figure 4] 1 is a scanning electron microscope (SEM) image of a catalytic electrode according to an embodiment of the present disclosure. [Diagram 5] 1 is an EDS (Energy Dispersive Spectrometer) mapping image of a catalytic electrode according to an embodiment of the present disclosure. [Figure 6] 1 is a graph showing the results of XRD (X-Ray Diffraction) analysis of catalytic electrodes according to an example and a comparative example of the present disclosure. [Figure 7] 1 is a graph showing the results of XPS (X-ray Photoelectron Spectroscopy) analysis of catalytic electrodes according to an example and a comparative example of the present disclosure. [Figure 8] 1 is a graph showing the results of XPS (X-ray Photoelectron Spectroscopy) analysis of catalytic electrodes according to an example and a comparative example of the present disclosure. [Figure 9] 1 is a graph showing the amount of iridium metal supported, measured by performing an inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis on catalytic electrodes according to an embodiment and a comparative example of the present disclosure. [Figure 10] 1 is a graph showing the oxygen evolution reaction performance of catalytic electrodes according to an example and a comparative example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Structural or functional descriptions of the embodiments disclosed in this specification or application are provided solely for the purpose of describing embodiments according to the technical concept of the present invention, and the embodiments according to the technical concept of the present invention may be implemented in various forms other than the embodiments disclosed in this specification or application, and the technical concept of the present invention should not be construed as being limited to the embodiments described in this specification or application.

[0025] catalyst electrode

[0026] In one aspect of the present disclosure, a catalytic electrode is provided that includes a metal layer and a catalyst layer formed on the metal layer, the catalyst layer including iridium and palladium.

[0027] 1 is a diagram for explaining a catalytic electrode according to an embodiment of the present disclosure. Hereinafter, the catalytic electrode according to the embodiment of the present disclosure will be explained with reference to FIG.

[0028] Referring to FIG. 1, a catalytic electrode 100 includes a metal layer 10 and a catalytic layer 20 .

[0029] The metal layer 10 can function as a substrate on which the catalytic metal is deposited, and in one embodiment, the metal layer 10 can include one or more selected from the group consisting of metal mesh, metal foam, metal foil, metal felt, and metal fiber. In one embodiment, the metal layer 10 can also include one or more metals selected from the group consisting of titanium, nickel, and stainless steel. For example, the metal layer can include, but is not limited to, titanium mesh.

[0030] The catalytic layer 20 is formed on the metal layer 10 and includes iridium and palladium. In an embodiment, the iridium and palladium may be deposited on the metal layer 10 by an electrochemical method. In an embodiment, at least a portion of the iridium and palladium contained in the catalytic layer 20 may be chemically bonded to each other. That is, at least a portion of the iridium and palladium contained in the catalytic layer 20 may be chemically bonded to each other, thereby changing the electronic structure of at least a portion of the iridium and palladium contained in the catalytic layer 20. By changing the electronic structure of at least a portion of the iridium and palladium contained in the catalytic layer 20, particularly by changing the electronic structure of at least a portion of the iridium contained in the catalytic layer 20, the activity of the catalytic electrode 100 for the oxygen evolution reaction may be improved, and as a result, the oxygen evolution performance of the catalytic electrode 100 may be improved.

[0031] In the embodiment, the iridium and palladium contained in the catalytic layer 20 may be in direct contact with the metal layer 10. That is, as described above, the iridium and palladium may be directly deposited on the metal layer 10 through an electrochemical method, and a chemical bond may be formed between the metal layer 10 and the catalytic layer 20. As a result, the electron transfer performance and durability of the catalytic electrode 100 may be improved.

[0032] In the embodiment, the catalyst layer 20 may not include a binder. As described above, the iridium and palladium are directly deposited on the metal layer 10 through an electrochemical method, and a chemical bond can be formed between the metal layer 10 and the catalyst layer 20, so that the catalyst layer 20 can be formed on the metal layer 10 without using a separate binder. The commonly used Nafion binder is a PFAS (Per- and polyfluoroalkyl substances) material, which may cause environmental problems. In addition, it is possible to prevent a decrease in activity and durability due to the decomposition of the Nafion binder during the reaction. Furthermore, since the catalyst layer is deposited directly on the metal layer without using a binder, the chemical bond between the metal layer and the catalyst layer is strengthened, electron transfer is facilitated, and durability is improved.

[0033] The catalytic electrode 100 according to the embodiment of the present disclosure can have the same or even better oxygen generation performance as conventional precious metal catalytic electrodes, even with a smaller metal loading amount than conventional precious metal catalytic electrodes.

[0034] The catalytic electrode 100 according to the embodiment of the present disclosure may be included in a water splitting device or in a fuel cell, but the application of the catalytic electrode 100 is not limited thereto.

[0035] Method for manufacturing catalytic electrodes

[0036] In another aspect of the present disclosure, a method for producing a catalytic electrode is provided that includes depositing iridium and palladium on a metal substrate.

[0037] 2 is a flow chart for explaining a method for manufacturing a catalytic electrode according to an embodiment of the present disclosure. Hereinafter, a method for manufacturing a catalytic electrode according to an embodiment of the present disclosure will be described with reference to FIG.

[0038] A method for manufacturing a catalytic electrode according to another aspect of the present disclosure includes depositing iridium and palladium on a metal substrate. The metal substrate may have the same composition as the metal layer described above, and thus, in one embodiment, the metal substrate may include one or more selected from the group consisting of metal mesh, metal foam, metal foil, metal felt, and metal fiber, and in one embodiment, the metal substrate may include one or more metals selected from the group consisting of titanium, nickel, and stainless steel.

[0039] Referring to FIG. 2, the step of depositing iridium and palladium on a metal substrate may include the steps of: introducing the metal substrate into a solution containing an iridium precursor and a palladium precursor (operation S110); and electrochemically depositing iridium and palladium on the metal substrate (operation S120).

[0040] In one embodiment, the iridium precursor may be an iridium salt, such as, but not limited to, one or more selected from the group consisting of iridium chloride, iridium chloride hydrate, iridium bromide, iridium acetylacetonate, hexachloroiridic acid, sodium hexachloroiridate, and potassium hexachloroiridate.

[0041] In one embodiment, the palladium precursor may be a palladium salt, such as, but not limited to, one or more selected from the group consisting of palladium nitrate, palladium chloride, palladium bromide, palladium sulfate, palladium acetylacetonate, palladium iodide, palladium acetate, palladium propionate, palladium dicyanide, palladium trifluoroacetate, ethylenediaminepalladium chloride, and palladium hexafluoroacetylacetonate.

[0042] In one embodiment, the solution containing the iridium precursor and the palladium precursor may contain an acidic solvent in consideration of dissolving the iridium precursor and the palladium precursor. If the pH of the solution containing the iridium precursor and the palladium precursor is relatively high, deposition efficiency may decrease due to the formation of metal precipitates. The strong acidic solvent may be, for example, but is not limited to, a sulfuric acid solution.

[0043] The step of electrochemically depositing iridium and palladium on the metal substrate (operation S120) may be performed by applying a voltage across one or more electrodes in contact with a solution containing the iridium precursor and the palladium precursor.

[0044] In one embodiment, the step of electrochemically depositing iridium and palladium on a metal substrate may be performed using a two-electrode electrochemical system, where one or more electrodes in contact with the solution containing iridium and palladium precursors may include a working electrode and a reference electrode. In another embodiment, the step of electrochemically depositing iridium and palladium on a metal substrate may be performed using a three-electrode electrochemical system, where one or more electrodes in contact with the solution containing iridium and palladium precursors may include a working electrode, a counter electrode and a reference electrode. A three-electrode electrochemical system can be seen in Figure 3, where the electrochemical system includes a working electrode 200, a reference electrode 300 and a counter electrode 400, which are in contact with a solution containing iridium and palladium precursors 500, which serves as an electrolyte.

[0045] In embodiments, the working electrode may be the electrode at which the electrochemical reaction occurs, the counter electrode may be the electrode that completes the electrical circuit to allow charge transfer in the electrochemical system, and the reference electrode may be an electrode that serves as a reference for measuring the potential of the working electrode. In a two-electrode electrochemical system, the reference electrode may simultaneously act as the counter electrode. That is, since the electrochemical reaction occurs at the working electrode, the working electrode may include a metal substrate on which the iridium and palladium are deposited.

[0046] In an embodiment, a voltage may be applied to the working electrode and the reference electrode or the working electrode, the reference electrode and the counter electrode, and by applying the voltage, iridium and palladium of a solution containing an iridium precursor and a palladium precursor may be deposited on a metal substrate included in the working electrode. In one embodiment, the magnitude of the applied voltage may be gradually increased. Also, in one embodiment, the magnitude of the applied voltage may be increased at a constant rate. By applying the voltage, crystal nuclei of palladium and iridium metal ions may be generated on the metal substrate, and then the crystals may grow by repeatedly applying a voltage of an increased magnitude. In this way, iridium and palladium metals may be uniformly and efficiently deposited on the metal substrate.

[0047] In one embodiment, before the step of depositing iridium and palladium on the metal substrate, a step of treating the metal substrate with an acid may be further performed, which removes oxides or foreign matter formed on the metal substrate, so that iridium and palladium ions can be effectively deposited on the metal substrate.

[0048] In one embodiment, the method may further include a step of heat-treating the metal substrate on which the iridium and palladium are deposited, after the step of depositing the iridium and palladium on the metal substrate, so that the iridium and palladium deposited on the metal substrate have a stable metallic phase.

[0049] membrane electrode assembly

[0050] In yet another aspect of the present disclosure, there is provided a membrane electrode assembly including an electrolyte membrane, an anode located on one side of the electrolyte membrane, and a cathode located on another side of the electrolyte membrane, the anode including a metal layer and a catalyst layer formed on the metal layer, the catalyst layer including iridium and palladium.

[0051] In yet another aspect of the present disclosure, a membrane electrode assembly may include the above-mentioned catalytic electrode as an anode. That is, the anode may include a metal layer and a catalytic layer formed on the metal layer and including iridium and palladium.

[0052] In addition, the membrane electrode assembly provided in yet another aspect of the present disclosure may include a cathode including a cathode catalyst, and the cathode catalyst may be a material commonly used in the art. For example, the cathode catalyst may be one selected from the group consisting of platinum, ruthenium, iridium, osmium, palladium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and oxides thereof, or a mixture of two or more of them, but is not limited thereto.

[0053] In addition, the membrane electrode assembly provided in yet another aspect of the present disclosure may include an electrolyte membrane disposed between the anode and the cathode. For example, the electrolyte membrane may be a polymer electrolyte membrane including a fluorine-based polymer or a hydrocarbon-based polymer, but is not limited thereto.

[0054] The membrane electrode assembly provided in yet another aspect of the present disclosure may be included in a water electrolysis device or a fuel cell.

[0055] Working Example

[0056] The catalytic electrode and the method for manufacturing the catalytic electrode according to the present disclosure will be described in more detail below with reference to examples and comparative examples. However, the following examples and comparative examples are merely illustrative for explaining the present disclosure in more detail, and the present disclosure is not limited by the following examples and comparative examples.

[0057] Example 1: Preparation of Ir-Pd / Ti Electrode

[0058] Iridium chloride and palladium nitrate were added to a sulfuric acid solution having a concentration of 0.5 M at concentrations of 200 μM and 400 μM, respectively, and ultrasonic treatment and stirring were performed until the added iridium chloride and palladium nitrate were completely dissolved.

[0059] To electrochemically deposit the precursor solution thus prepared onto the working electrode, an electrochemical cell was used, consisting of a titanium mesh acid-treated with oxalic acid (5 wt%) as the working electrode, a graphite rod as the counter electrode, and an Ag / AgCl as the reference electrode.

[0060] The titanium mesh was placed in the precursor solution at 1 cm 2 After immersion in the titanium mesh with a 300% area, iridium and palladium were evaporated onto the titanium mesh working electrode by repeating Linear Sweep Voltammetry (LSV) 300 times at a scan rate of 10 mV / s in the voltage range of 0.02 V to 0.17 V (vs RHE). Finally, the Ir-Pd / Ti electrode was fabricated by heat treatment at 300 degrees for 1 hour in a H2 atmosphere.

[0061] <Comparative Example 1> Preparation of Ir / Ti electrode

[0062] An electrode was prepared in the same manner as in Example 1, except that the titanium mesh was placed in an iridium precursor solution to which no palladium precursor was added. The iridium precursor solution contained iridium chloride at a concentration of 500 μM.

[0063] Comparative Example 2: Preparation of Pd / Ti Electrode

[0064] An electrode was prepared in the same manner as in Example 1, except that the titanium mesh was placed in a palladium precursor solution to which no iridium precursor was added. The palladium precursor solution contained palladium nitrate at a concentration of 500 μM.

[0065] <Comparative Example 3> - Preparation of IrO2 electrode

[0066] A commonly used oxidizing electrode catalyst, IrO2 black (100% by weight, Alfa Aesar), was prepared.

[0067] <Experimental Example 1> - Morphological analysis of the electrode of Example 1

[0068] Using a scanning electron microscope (Apreo) equipped with an EDS detector, an SEM image and an EDS mapping analysis result were obtained for the electrode of Example 1. The SEM image for the electrode of Example 1 is shown in FIG. 4, and the EDS mapping analysis result is shown in FIG. 5.

[0069] Referring to FIG. 4, it can be seen that a branched nanostructure was formed on the titanium mesh of the electrode of Example 1.

[0070] Also, referring to FIG. 5, it can be seen that iridium and palladium are simultaneously present on the titanium mesh of the electrode of Example 1, and that both iridium and palladium are uniformly deposited over the entire titanium mesh.

[0071] <Experimental Example 2>-Analysis of deposition characteristics of catalyst layer in electrode

[0072] The metal crystal planes were confirmed by X-ray diffraction analysis (XRD; PANalytical) for the electrodes of Example 1, Comparative Example 1, and Comparative Example 2. At this time, measurements were performed at 40 kV and 100 mA using Cu Kα radiation, and the measurements were performed only in the range of 10 to 80° at a scanning speed of 6° per minute at intervals of 0.01°. The results are shown in FIG.

[0073] 6, an iridium peak was observed in the XRD analysis result of the electrode of Comparative Example 1, and a palladium peak was observed in the XRD analysis result of the electrode of Comparative Example 2. Meanwhile, an iridium peak and a palladium peak were simultaneously observed in the electrode of Example 1, confirming that iridium and palladium are simultaneously present in the catalyst layer deposited on titanium of the electrode of Example 1.

[0074] In addition, the electronic structures of the metals present on the electrode surfaces of the electrodes of Example 1, Comparative Example 1, and Comparative Example 2 were confirmed by X-ray photoelectron spectroscopy (XPS), and the results are shown in FIGS.

[0075] Referring to FIG. 7, the Ir4f peaks of the electrode of Example 1 and the electrode of Comparative Example 1 were examined, and it was found that the peak of Example 1 was shifted to the left compared to the peak of Comparative Example 1. This suggests that palladium is also present in addition to iridium in the catalytic layer of the electrode of Example 1, and that the electronic structure of iridium is changed due to the presence of palladium.

[0076] Referring to FIG. 8, the Pd3d peaks of the electrode of Example 1 and the electrode of Comparative Example 2 were examined, and it was found that the peak of Example 1 was shifted to the right compared to the peak of Comparative Example 2. This suggests that iridium is also present in addition to palladium in the catalytic layer of the electrode of Example 1, and that the electronic structure of palladium is changed due to the presence of iridium.

[0077] In addition, the iridium content (wt%) in the catalytic layer of the electrodes prepared in Example 1 and Comparative Example 3 was determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES, NexION 300X), and the results are shown in FIG. 9.

[0078] Referring to FIG. 9, the iridium content in the catalytic layer of the electrode of Example 1 was 0.47 mg / cm 2 At the level, 1.7 mg / cm 2 It can be seen that the loading amount of iridium, which is an active metal, is significantly lower than that of the electrode having the same iridium content as Comparative Example 3. Despite the significantly lower iridium loading amount, the electrode of Example 1 can have better activity than the electrode of Comparative Example 3, as described below.

[0079] <Experimental Example 3> - Evaluation of the electrochemical properties of the electrodes

[0080] The electrodes of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were used as working electrodes, Ag / AgCl (sat. 3M KCl) as a reference electrode, and a graphite rod as a counter electrode to measure the polarization of the oxygen evolution reaction for the electrodes of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Each electrode was placed in a 0.5M H2SO4 acidic solution, and the oxygen evolution reaction was carried out at a scan rate of 10mV / s at room temperature.

[0081] The polarization results for the oxygen evolution reaction are shown in FIG. 10 and Table 1 below, where all measurements are expressed "vs RHE (reversible hydrogen electrode)".

[0082] [Table 1]

[0083] Referring to FIG. 10 and Table 1, a current density of 10 mAcm -2 It can be seen that the performance of the standard oxygen generation reaction is excellent in the order of activity for Example 1, Comparative Example 3, Comparative Example 1, and Comparative Example 2.

[0084] Example 1 is 10 mAcm -2 In order to obtain a current density value corresponding to the above, an overvoltage of only 280 mV is required, which is 22 mV smaller than that of Comparative Example 3 and 48 mV smaller than that of Comparative Example 1.

[0085] As confirmed by the ICP analysis results of Example 1, Example 1 has a significantly lower catalytic metal loading amount than Comparative Example 3, but the oxygen generation performance is superior to that of Comparative Example 3.

[0086] In other words, it is expected that the electrode of Example 1 has iridium and palladium simultaneously deposited on a titanium mesh, and that the electronic structure of the active metal iridium is changed by their mutual interaction, thereby significantly improving the oxygen generation performance.

Claims

1. A metal layer; a catalyst layer formed on the metal layer; The catalyst layer is A catalytic electrode comprising iridium and palladium.

2. At least a portion of the iridium and palladium contained in the catalyst layer is The catalytic electrodes of claim 1 which are chemically bonded to each other.

3. The catalytic electrode is The catalyst layer has a concentration of 0.02 to 0.8 mg / cm ２ and the catalyst layer contains iridium in an amount of 0.1 to 0.8 mg / cm ２ The catalytic electrode according to claim 1 , comprising said palladium in an amount of:

4. The metal layer is 10. The catalytic electrode of claim 1, comprising one or more selected from the group consisting of metal mesh, metal foam, metal foil, metal felt, and metal fiber.

5. The metal layer is 5. The catalytic electrode of claim 4, comprising one or more metals selected from the group consisting of titanium, nickel, and stainless steel.

6. The iridium and palladium are 10. The catalytic electrode of claim 1, electrochemically deposited on said metal layer.

7. The iridium and palladium are The catalytic electrode of claim 1 in direct contact with the metal layer.

8. The catalyst layer is 8. The catalytic electrode of claim 7, which is binder-free.

9. A method for producing a catalytic electrode, comprising depositing iridium and palladium on a metal substrate.

10. The step of depositing iridium and palladium on the metal substrate comprises: immersing the metal substrate in a solution containing an iridium precursor and a palladium precursor; and electrochemically depositing the iridium and palladium on the metal substrate.

11. At least a portion of the iridium and palladium deposited on the metal substrate is The method for producing a catalytic electrode according to claim 10, wherein the electrodes are chemically bonded to each other.

12. The step of electrochemically depositing iridium and palladium on the metal substrate comprises: The method of claim 10, wherein the method is carried out by applying a voltage through one or more electrodes in contact with the solution.

13. The method for producing a catalytic electrode according to claim 12, wherein the voltage is increased at a constant rate.

14. The method for manufacturing a catalytic electrode according to claim 9, further comprising the step of heat treating the metal substrate on which the iridium and palladium are deposited.

15. Prior to the step of depositing iridium and palladium on the metal substrate, The method for producing a catalytic electrode according to claim 9, further comprising the step of treating the metal substrate with an acid.

16. An electrolyte membrane; an anode located on one side of the electrolyte membrane; a cathode located on the other side of the electrolyte membrane; The anode is A metal layer; a catalyst layer formed on the metal layer and containing iridium and palladium.

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