Catalyst production method, catalyst, electrode, membrane electrode assembly, and water electrolysis device

Abstract

Provided are: a catalyst production method by which a catalyst can be produced at a low temperature in a short time; a catalyst which is highly active; and an electrode, a membrane electrode assembly, and a water electrolysis device each employing the catalyst.　The catalyst production method is for producing a catalyst containing Co and Mo, and comprises: preparing a substrate and a solution comprising Co, Mo, a supporting electrolyte, and water; immersing the substrate in the solution; and electrochemically depositing Co and Mo on the substrate.

Description

Method for producing catalyst, catalyst, electrode, membrane electrode assembly, and water electrolysis device

[0001] The present invention relates to a method for producing a catalyst, a catalyst, an electrode, a membrane electrode assembly, and a water electrolysis device.

[0002] Technologies for storing and transporting renewable energy have been attracting attention. One possible example is using renewable energy to split water to produce hydrogen and oxygen, and then storing and transporting the hydrogen. As a water splitting method, for example, solid alkaline water electrolysis can adapt to output fluctuations and allows the use of materials other than precious metals, such as stainless steel, for bipolar plates. This technology is expected to achieve both high performance and low cost, and is attracting attention as a next-generation technology. Currently, electrodes used in water electrolysis are mainly those that have a catalyst layer in which a precious metal, such as platinum or ruthenium, is supported on a porous support (see, for example, Patent Documents 1 and 2). Meanwhile, the present inventors have disclosed base metal catalysts suitable for anode electrodes and methods for producing the same in Patent Documents 3 and 4.

[0003] Japanese Patent Publication No. 2020-94282 Japanese Patent Publication No. 2019-519080 International Publication No. 2022 / 250119 International Publication No. 2022 / 250122

[0004] Research is also underway into catalysts that do not contain precious metals for the cathode (hydrogen evolution reaction (HER)) electrode. However, currently, base metal catalysts for HER have low activity, and high activity is required. In addition, base metal catalysts are manufactured using methods such as the furnace method and hydrothermal synthesis, which require long-term processing under high temperature and pressure.

[0005] An object of the present disclosure is to provide a method for producing a catalyst that can be produced at low temperature in a short time, a highly active catalyst, an electrode that uses the catalyst, a membrane electrode assembly, and a water electrolysis device.

[0006] The present disclosure includes the following aspects. [1] A method for producing a catalyst containing Co and Mo, comprising: preparing a solution containing Co, Mo, a supporting electrolyte, and water, and a substrate; and electrochemically depositing Co and Mo on the substrate in the presence of the solution. [2] The method for producing a catalyst according to [1] above, wherein the substrate is a metal substrate. [3] The method for producing a catalyst according to [1] or [2] above, wherein the substrate is a porous substrate. [4] The method for producing a catalyst according to any of [1] to [3] above, wherein the supporting electrolyte contains a salt of an alkali metal or an alkaline earth metal. [5] The method for producing a catalyst according to any of [1] to [4] above, wherein the supporting electrolyte contains a salt of a divalent cation. [6] The method for producing a catalyst according to any of [1] to [5] above, wherein the supporting electrolyte contains a calcium salt. [7] The method for producing a catalyst according to any of [1] to [6] above, wherein the Co / Mo ratio (molar ratio) in the solution is 1.0 to 4.0. [8] The method for producing a catalyst according to any one of [1] to [7], wherein the catalyst obtained contains an alkali metal or an alkaline earth metal. [9] A catalyst containing at least one selected from alkali metals and alkaline earth metals, Co, and Mo.

[10] The Co and Mo in the catalyst are preferably Co(OH) ２ , CoO(OH), and Mo ３ O ４The catalyst according to [9] above, which exists in the form of

[11] .

[11] The catalyst according to [9] or

[10] above, wherein the one or more selected from alkali metals and alkaline earth metals include Ca.

[12] The catalyst according to any of [9] to

[11] above, wherein the Co / Mo ratio (molar ratio) is 4.0 to 6.0.

[13] The catalyst according to any of [9] to

[12] above, wherein the concentration of the one or more selected from alkali metals and alkaline earth metals is 0.1 to 0.5 wt %.

[14] The catalyst according to any of [9] to

[13] above, which is used for the hydrogen evolution reaction (HER).

[15] An electrode comprising a catalyst layer on a substrate, wherein the catalyst layer comprises the catalyst according to any of [9] to

[14] .

[16] A membrane electrode assembly comprising an anode, a cathode, and an electrolyte membrane disposed between the anode and the cathode, wherein the cathode is the electrode according to

[15] .

[17] A water electrolysis device comprising: the membrane electrode assembly according to

[16] ; a power source that applies a voltage between the anode and the cathode; and a water supply unit that supplies water or an alkaline aqueous solution to the membrane electrode assembly.

[0007] The present disclosure provides a method for producing a catalyst that can be produced at low temperature in a short time, a highly active catalyst, an electrode that uses the catalyst, a membrane electrode assembly, and a water electrolysis device.

[0008] FIG. 1 is a schematic diagram showing an example of a method for producing a catalyst. FIG. 2 is a schematic cross-sectional view showing an example of an electrode. FIG. 3 is a schematic cross-sectional view showing an example of a water electrolysis device. FIG. 4 is a schematic diagram for explaining an electrochemical measurement method of an example. FIG. 5 is a graph showing the results of electrochemical measurement. FIG. 6 is an SEM image of a catalyst. FIG. 7 is a graph showing the results of electrochemical measurement. FIG. 8 is an SEM image of a catalyst. FIG. 9 is a graph showing the results of electrochemical measurement. FIG. 10 is a Raman spectrum of a catalyst.

[0009] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily required as means for solving the problems. For clarity, the following description and drawings have been simplified as appropriate. Furthermore, matters necessary for implementing the present invention that are not specifically mentioned in this specification can be understood as design matters for those skilled in the art based on prior art in the relevant field. The same components in each embodiment are designated by the same reference numerals, and their description will be omitted or simplified. In this specification, "noble metal" is a general term for gold, silver, platinum, palladium, rhodium, iridium, ruthenium, and osmium. Furthermore, "base metal" is a general term for copper, lead, nickel, zinc, iron, aluminum, tin, tungsten, molybdenum, tantalum, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, and thallium. Unless otherwise specified, the range of values ​​indicated by "to" includes the values ​​before and after it as the lower and upper limits.

[0010] [Method for Producing Catalyst] The catalyst production method of the present disclosure (hereinafter also referred to as the present production method) is a method for producing a catalyst containing Co and Mo, characterized in that the substrate is immersed in the solution and Co and Mo are electrochemically deposited on the substrate. This production method does not require long-term treatment under high temperature and pressure, as in the furnace method or hydrothermal synthesis method, and a base metal catalyst for HER can be obtained by treatment at room temperature for, for example, several tens of minutes. Furthermore, as described below, by selecting the supporting electrolyte and other elements used in this production method, a base metal catalyst with excellent HER activity can be obtained.

[0011] This production method will be specifically described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of a catalyst production method. In this production method, first, a solution 51 containing Co, Mo, a supporting electrolyte, and water is prepared. Next, a substrate 52 serving as a working electrode and a counter electrode 53 are immersed in the solution 51, and a voltage is applied between the substrate 52 and the counter electrode 53. In this way, Co and Mo are electrodeposited onto the substrate 52, thereby obtaining a catalyst containing Co and Mo.

[0012] The substrate 52 may be a substrate having at least a portion thereof electrically conductive, and is preferably a metal substrate. Examples of materials for the metal substrate include noble metals, base metals, and alloys thereof. From the viewpoint of production costs, base metals and alloys thereof are preferred, and from the viewpoint of availability, Ni, Ti, Cr, Fe, and alloys thereof (e.g., stainless steel) are more preferred.

[0013] Furthermore, the substrate 52 on which the catalyst is deposited and provided with a catalyst layer can be used as an electrode. In consideration of this, a porous substrate is preferred for the substrate 52 in terms of increasing the contact area between the catalyst and water and the diffusibility of water and gas. As a porous substrate, a foam metal layer is particularly preferred, and nickel foam is more preferred. Furthermore, according to this manufacturing method, a catalyst layer can also be formed on the inner surface of the porous substrate.

[0014] If necessary, the substrate 52 may be subjected to known pretreatments, such as degreasing, washing with water, surface conditioning, chemical conversion treatment, and drying.

[0015] The thickness of the substrate 52 is not particularly limited and may be adjusted appropriately depending on the application, such as the size of the water electrolysis device, etc. The thickness of the substrate 52 can be adjusted appropriately within the range of 50 μm to 1,000 μm, for example.

[0016] In the solution 51, Co and Mo are usually used in a state of being dissolved in water. In the solution 51, cobalt is preferably present in the form of hydroxide and / or oxyhydroxide. Molybdenum is preferably present in the form of Mo. ３ The hydrate form of O is preferred.

[0017] The supporting electrolyte is a compound used to improve the conductivity of a solution, and is an ionic compound. Examples of ionic compounds include acids such as hydrochloric acid and nitric acid, and bases such as sodium hydroxide and potassium hydroxide. In this production method, the supporting electrolyte preferably contains a salt of an alkali metal or alkaline earth metal, since a catalyst with excellent HER activity can be obtained. When a supporting electrolyte containing an alkali metal or alkaline earth metal is used, the alkali metal or alkaline earth metal is incorporated into the catalyst when a catalyst layer is formed on the substrate surface, forming a microstructure on the catalyst surface. As a result, it is presumed that the surface area of ​​the catalyst is increased, further improving HER activity.

[0018] Examples of alkali metals and alkaline earth metals include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium. To obtain a catalyst with superior HER activity, it is preferable to use a salt containing a divalent cation as the supporting electrolyte, and it is more preferable to use a salt containing calcium. When a solution containing calcium is used, a very fine nanostructure is formed on the surface of the catalyst layer, further improving HER activity.

[0019] The counter anion in the supporting electrolyte is not particularly limited because it does not significantly affect the performance of the catalyst. Specific examples of the counter anion include halogen atoms such as fluorine, chlorine, bromine, and iodine. Specific examples of the supporting electrolyte include NaCl, NaBr, NaI, KF, KCl, KBr, KI, and MgCl. ２ , MgBr ２ , CaCl ２ , CaBr ２ , CaI ２ , BaCl ２ , BaBr ２ The supporting electrolyte may be used alone or in combination of two or more.

[0020] From the viewpoint of the HER activity of the resulting catalyst, the molar ratio of Co to Mo (Co / Mo ratio) in solution 51 is preferably 1.0 to 4.0, and more preferably 1.5 to 4.0. From the viewpoint of the HER activity of the catalyst, the concentration of Co in solution 51 is preferably 10 to 120 mMol, and more preferably 20 to 100 mMol. From the viewpoint of the HER activity of the catalyst, the concentration of Mo in solution 51 is preferably 5 to 100 mMol, and more preferably 10 to 80 mMol. Furthermore, from the viewpoint of the HER activity of the catalyst, the concentration of the supporting electrolyte in solution 51 is preferably 50 to 500 mMol, and more preferably 100 to 400 mMol. Note that the composition of solution 51 and the composition of the resulting catalyst may not match.

[0021] The voltage applied between the substrate 52 and the counter electrode 53 is preferably adjusted so that the current density is constant, in terms of the uniformity of the formed catalyst. The current density is not particularly limited, and may be, for example, −10 mA / cm ２ ~-200mA / cm ２ The temperature during catalyst production is not particularly limited and may be appropriately adjusted within a range of, for example, 5 to 40°C. The voltage application time is not particularly limited and may be appropriately adjusted, for example, to about 1 to 30 minutes. During voltage application, solution 51 may be stirred as needed. According to this production method, a catalyst with excellent HER activity can be obtained with a short treatment time.

[0022] [Catalyst and Electrode] The catalyst of the present disclosure (hereinafter also referred to as the present catalyst) is characterized by containing one or more selected from alkali metals and alkaline earth metals, as well as Co and Mo. The present catalyst can be suitably produced by the present production method. By containing one or more selected from alkali metals and alkaline earth metals, the present catalyst forms a microstructure on its surface, resulting in excellent HER activity. As shown in FIG. 2 , the electrode 60 of the present disclosure includes a catalyst layer 54 containing the present catalyst on the surface of a substrate 52. The present production method can suitably produce the electrode 60 shown in FIG. 2 . The electrode of the present disclosure may further include a diffusion layer on one side of the electrode 60 (not shown in FIG. 2 ). The configuration of the diffusion layer may be similar to that of the first diffusion layer 12 described below.

[0023] The material and the like of the substrate 52 are as described above. The thickness of the catalyst layer 54 is not particularly limited and can be adjusted appropriately within the range of, for example, 1 to 1,000 nm, and preferably 1 to 500 nm. The thickness of the catalyst layer can be adjusted by the current density, the voltage application time, and the like in the manufacturing method.

[0024] The ratio of Co to Mo (Co / Mo ratio) in the catalyst is preferably 4.0 to 6.0, more preferably 4.0 to 5.8, in molar ratio. The concentration of one or more metals selected from alkali metals and alkaline earth metals is preferably 0.1 to 0.5 wt %, more preferably 0.15 to 0.4 wt %, based on the catalyst layer. The one or more metals selected from alkali metals and alkaline earth metals preferably include an alkaline earth metal, more preferably calcium. Co and Mo in the catalyst are preferably Co(OH) ２ , CoO(OH), and Mo ３ O ４ These include those that exist in the form of

[0025] This catalyst suppresses overvoltage and has excellent HER activity, and also suppresses the internal resistance by suppressing the electric double layer capacitor.

[0026] [Membrane electrode assembly and water electrolysis apparatus] A membrane electrode assembly according to the present disclosure (hereinafter also referred to as the present membrane electrode assembly) includes an anode, a cathode, and an electrolyte membrane disposed between the anode and the cathode, where the cathode is the electrode according to the present disclosure. A water electrolysis apparatus according to the present disclosure includes the present membrane electrode assembly, a power source that applies a voltage between the anode and the cathode, and a water supply unit that supplies water or an alkaline aqueous solution to the present membrane electrode assembly.

[0027] The configurations of a membrane electrode assembly and a water electrolysis device will be described with reference to FIG. 3 . FIG. 3 is a schematic cross-sectional view showing an example of the water electrolysis device. The water electrolysis device 1 shown in the example of FIG. 3 includes an electrolyte membrane 5, an anode 10 disposed on one side of the electrolyte membrane 5, a cathode 20 disposed on the other side, a power source 7 connected to the anode 10 and the cathode 20, and a water supply unit that supplies water or an alkaline aqueous solution to the cathode 20. The anode 10 needs to include at least an anode catalyst 11 and may further include a first diffusion layer 12. The cathode 20 needs to include at least a cathode catalyst 21 and may further include a second diffusion layer 22. The membrane electrode assembly 8 includes at least an anode catalyst 11 disposed on one side of the electrolyte membrane 5 and a cathode catalyst 21 disposed on the other side. In the present disclosure, the cathode 20 is the electrode 60. In the example of Fig. 3, the cell 6 further includes separators 13 and 23 on the outer sides of the anode 10 and the cathode 20, respectively. The water electrolysis apparatus 1 may be a single cell 6, or may be configured by stacking a plurality of cells 6. The water supply unit supplies water to the membrane electrode assembly 8, for example, to at least one of the anode 10 and the cathode 20. Use of the present electrode as the cathode 20 makes it possible to obtain a water electrolysis apparatus with high water electrolysis performance.

[0028] When the water electrolysis device is a solid alkaline water electrolysis device, an anion conductive membrane is used as the electrolyte membrane 5. For example, when a voltage is applied to both electrodes while supplying water or an alkaline aqueous solution to the cathode 20, the following reaction occurs on the cathode 20 side, generating hydrogen gas: ２ O + 2e － →2OH － +H ２ Hydroxide ion (OH － ) permeates the electrolyte membrane 5 and moves to the anode 10. At the anode 10, the following reaction occurs, generating oxygen gas: － →H ２ O+1 / 2O ２ +2e －The generated hydrogen and oxygen are discharged from the cell 6 through gas flow paths 14, 24 provided in the separators 13 and 23, respectively. The gas flow paths are connected to a storage tank or the like via a gas-liquid separator (not shown), and the hydrogen and oxygen are each stored in the storage tank or the like after water is separated from them in the gas-liquid separator.

[0029] The water supplied to the present water electrolysis apparatus may be pure water or an alkaline aqueous solution. By using an alkaline aqueous solution, water electrolysis can be performed more efficiently than with pure water. The solute in the alkaline aqueous solution is not particularly limited, and may be, for example, 1 M potassium hydroxide. The thickness of the electrolyte membrane is not particularly limited, but may be appropriately adjusted within the range of, for example, 1 to 100 μm, and is preferably 2 to 80 μm.

[0030] The anode 10 includes at least an anode catalyst 11 and may further include a first diffusion layer 12. The anode catalyst 11 can be appropriately selected from known catalysts, including, for example, platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, metal compounds thereof, metal oxides, and fine particles of alloys containing two or more of these metals. The anode catalyst 11 is preferably porous in terms of the contact area with water and the diffusion of water and gas. The porous catalyst layer may, for example, contain particles of the above-mentioned metals that serve as catalysts and a binder component, or may be a metal particle linkage formed by fusion of the above-mentioned metal particles. The catalysts described in Patent Documents 3 and 4 may also be used as the anode catalyst. The thickness of the anode catalyst 11 is not particularly limited, but may be, for example, 0.01 to 100 μm, preferably 0.01 to 10 μm. The first diffusion layer 12 can be appropriately selected from known gas diffusion layers, and examples thereof include a foam metal layer such as nickel foam, and a porous carbon layer.

[0031] The water electrolysis apparatus may have separators 13 and 23 on the outside of the anode 10 and the cathode 20, respectively. The separators do not need to be platinum-coated or the like, and may be made of an appropriate material such as carbon or stainless steel. When the separators 13 and 23 are conductive, the separator 13 may serve as a first main electrode and the separator 23 may serve as a second main electrode, and a power source 7 may be connected to the first and second main electrodes to apply a voltage to the anode and the cathode.

[0032] The separators 13 and 23 may have gas flow channels 14 and 24. Oxygen generated at the anode 10 and hydrogen generated at the cathode 20 are discharged through the gas flow channels 14 and 24, respectively, and stored in a storage tank or the like.

[0033] The power supply 7 is not particularly limited and can be appropriately selected from known DC power supplies. Because the water electrolysis apparatus has excellent response to input power, it can be suitably used with renewable energy sources such as solar power generation and wind power generation, which have large fluctuations in input power.

[0034] The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited to these examples, and the present invention can be modified appropriately without departing from the spirit and scope of the invention. Examples 1 to 13 are working examples, and Examples 14 to 16 are comparative examples.

[0035] [Production of catalyst] The following will be explained with reference to FIG. 1. Both the working electrode 52 and the counter electrode 53 were made of nickel foam (thickness: approximately 200 μm). The counter electrode 53 had a large area, and the working electrode 52 was large enough to be immersed entirely in the solution 51. In this example, a reference electrode (Ag / AgCl) (not shown) was used for measurement, forming a three-electrode system. The composition of the solution 51 shown in Table 1 was prepared. A voltage of -100 mA / cm was applied between the working electrode 52 and the counter electrode 53. ２ The catalyst was deposited under the condition of a constant current density of 1000 kJ / cm2 at room temperature (about 25° C.).

[0036]

[0037] [Measurement] <Surface Observation> The surface of each catalyst obtained was observed using a scanning electron microscope (SEM). <Electrochemical Measurement> This will be explained with reference to FIG. 4. A three-electrode system was formed using the catalyst (electrode 60) to be measured, a counter electrode 63, and a reference electrode 64. A large-area nickel foam was used as the counter electrode 63. A Hg / HgO electrode was used as the reference electrode 64. A 1 M KOH solution was used as the solution 61. N ２ After bubbling, the catalyst was placed in a nitrogen-saturated atmosphere, and then measurements were carried out at room temperature (approximately 25° C.) <Co / Mo ratio> The Co / Mo ratio and the proportions of alkali metals and alkaline earth metals in the catalyst were measured using an ICP optical emission spectrometer (ICP-OES).

[0038] [Results] (1) Comparison of Co / Mo ratios (Examples 1 to 5) The results of Examples 1 to 5 are shown in Table 2 and FIG. 5. SEM images of Examples 2, 4, and 5 are shown in FIG. 6. The HER activity was measured when the current density of the linear sweep voltammetry (LSV) curve in FIG. 5 was −10 mA / cm. ２ and -100mA / cm ２ The smaller the overvoltage, the better the HER activity. ＤＬ was calculated from the Nyquist diagram in Figure 5. ＤＬ The smaller the value, the lower the internal resistance and the higher the efficiency of hydrogen generation.

[0039]

[0040] As shown in Table 2 and Figure 5, all of the catalysts in Examples 1 to 5 exhibited good HER activity. Among them, the catalysts in Examples 2 to 4 (Co80Mo20, Co80Mo26.7, and Co80Mo40) were shown to have excellent HER activity. As shown in Figure 6, the catalyst surface in each example formed a fine structure, and the catalyst in Example 5 (Co80Mo40) showed some aggregation, with a tendency for the fine structure to become larger as the Mo content increased. In particular, the catalyst in Example 2 (Co80Mo20) exhibited a fine structure, demonstrating excellent HER activity.

[0041] (2) Comparison of supporting electrolytes (Example 2, Examples 6 to 8) The results of Example 2 and Examples 6 to 8 are shown in Table 3 and Figure 7. The measurement items were the same as those in (1) above.

[0042]

[0043] As shown in Table 3 and FIG. 7, the catalysts of Examples 2 and 6 to 8 all exhibited good HER activity. Among them, the catalyst of Example 8 (Co80Mo20-CaCl ２ 200) showed an extremely low overcurrent and high HER activity. The Ca concentration in the catalyst of Example 8 was 0.22 wt %.

[0044] (3) Comparison of Supporting Electrolytes Containing Alkaline Earth Metal Salts (Examples 8 to 10) The results of Examples 8 to 10 are shown in Table 4. SEM images of each example are shown in Figure 8. The measurement items were the same as those in (1) above.

[0045]

[0046] As shown in Table 4, the catalysts of Examples 8 to 10 all exhibited good HER activity, especially C ＤＬ As shown in Figure 8, the catalyst surface in each example forms a fine structure, and the Ca-containing catalyst in particular exhibits a very fine nanostructure, suggesting that this contributes to HER activity.

[0047] (4) Comparison of supporting electrolytes (halogen) (Example 2, Examples 11 to 13) The results of Example 2 and Examples 11 to 13 are shown in Table 5 and Figure 9. The measurement items were the same as those in (1) above.

[0048]

[0049] 9, good HER activity was obtained for the catalysts of Examples 2 and 11 to 13. On the other hand, there was little significant difference in HER activity depending on the type of halogen in the supporting electrolyte.

[0050] (5) Analysis of the phases in the catalyst The catalyst of Example 8 (Co80Mo20-CaCl ２200) was subjected to phase analysis by Raman spectroscopy. For comparison, catalysts of Examples 14 to 16 were produced using the solutions shown in Table 6 in the same manner as in the above [Catalyst Production]. Furthermore, nickel foam (NF) itself was also measured. The results are shown in Figure 10.

[0051]

[0052] As shown by a comparison between Examples 14 and 15, and a comparison between Examples 8 and 16, the catalysts produced in the presence of alkali metal or alkaline earth metal salts have increased hydroxides and oxyhydroxides of Co. Furthermore, the catalyst produced in the presence of calcium ions, as in Example 8, has increased active sites, which contributes to high HER activity.

[0053] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention.

[0054] This application claims priority based on Japanese Patent Application No. 2023-137468, filed on August 25, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0055] 1: Water electrolysis device, 5: Electrolyte membrane, 6: Cell, 7: Power source, 8: Membrane electrode assembly, 10: Anode, 11: Anode catalyst, 12: First diffusion layer, 13: Separator, 14: Gas flow path, 20: Cathode, 21: Cathode catalyst, 22: Second diffusion layer, 23: Separator, 24: Gas flow path, 51: Solution, 52: Substrate (working electrode), 53: Counter electrode, 54: Catalyst layer, 60: Electrode, 61: Solution, 63: Counter electrode, 64: Reference electrode.

Claims

1. A method for producing a catalyst containing Co and Mo, comprising: preparing a solution containing Co, Mo, a supporting electrolyte, and water, and a substrate; and electrochemically depositing Co and Mo on the substrate in the presence of the solution.

2. The method for producing a catalyst according to claim 1, wherein the substrate is a metal substrate.

3. The method for producing a catalyst according to claim 1, wherein the substrate is a porous substrate.

4. The method of claim 1, wherein the supporting electrolyte comprises a salt of an alkali metal or an alkaline earth metal.

5. The method of claim 1, wherein the supporting electrolyte comprises a salt of a divalent cation.

6. The method for producing the catalyst of claim 1, wherein the supporting electrolyte comprises a calcium salt.

7. The method for producing a catalyst according to claim 1, wherein the Co / Mo ratio (molar ratio) in the solution is 1.0 to 4.

0.

8. A method for producing a catalyst according to any one of claims 1 to 7, wherein the catalyst obtained comprises an alkali metal or an alkaline earth metal.

9. A catalyst comprising at least one selected from alkali metals and alkaline earth metals, Co and Mo.

10. Co and Mo in the catalyst are converted into Co(OH) ２ , CoO(OH), and Mo ３ O ４ The catalyst of claim 9, which is present in the form of 11. The catalyst according to claim 9, wherein the at least one selected from the alkali metals and alkaline earth metals comprises Ca.

12. The catalyst according to claim 9, wherein the Co / Mo ratio (molar ratio) is 4.0 to 6.

0.

13. The catalyst according to claim 9, wherein the concentration of one or more selected from the group consisting of alkali metals and alkaline earth metals is 0.1 to 0.5% by weight.

14. The catalyst of claim 9 for use in hydrogen evolution reactions (HER).

15. An electrode comprising a catalyst layer on a substrate, the catalyst layer comprising the catalyst according to any one of claims 9 to 14.

16. A membrane electrode assembly comprising: an anode; a cathode; and an electrolyte membrane disposed between said anode and said cathode, said cathode being the electrode according to claim 15.

17. A water electrolysis device comprising: the membrane electrode assembly according to claim 16; a power source that applies a voltage between the anode and the cathode; and a water supply unit that supplies water or an alkaline aqueous solution to the membrane electrode assembly.

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