JP2022185951A - Electrocatalyst and method for producing the same - Google Patents

Abstract

The present invention provides an electrode catalyst having a low overvoltage, a small Tafel slope, and long-term stability, and a method for producing the same.
The present invention is an electrode catalyst comprising a catalyst on a carbon substrate, wherein the catalyst comprises one metal element M selected from the group consisting of Zn, Cu, Ni, Mn, Fe and Cr. , V, and Co. The composite compound preferably contains the metal element M, _VOx , and Co. INDUSTRIAL APPLICABILITY The present invention can provide an electrode catalyst having a low overvoltage, a small Tafel slope, and long-term stability, and a method for producing the same.
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Description

TECHNICAL FIELD The present invention relates to an electrode catalyst and a method for producing the same.

Hydrogen emits zero _CO2 when burned, and is expected as a clean energy source to replace fossil fuels. In particular, the method of producing hydrogen by electrolysis of water uses renewable energy sources such as sunlight, wind power, and hydraulic power, so there are great expectations for it as a clean method of producing hydrogen that does not emit any _CO2 . It is

As an electrode for electrolysis of water, there is known one in which a platinum particle catalyst is fixed on an electrode base material such as a carbon base material. However, platinum is expensive and its resources are limited, so there is a demand for the development of techniques for reducing the amount of platinum used and the development of platinum-alternative catalysts and/or electrodes.

From this point of view, for example, Patent Document 1 and the like propose a novel catalyst containing a transition metal (e.g., Co, Ni, Mn, etc.) having a nano-sized fine structure as an electrode for water electrolysis. ing.

JP-A-2000-000470

However, in recent years, when producing hydrogen by electrolysis of water, the performance required for the electrode is a lower overvoltage, a small Tafel slope, long-term stability, etc., and these In terms of enhancing performance, conventional electrodes still have room for improvement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrode catalyst having a low overvoltage, a small Tafel slope, and long-term stability, and a method for producing the same.

As a result of intensive studies aimed at achieving the above object, the present inventors found that the above object can be achieved by forming a catalyst with a composite compound containing a specific metal element, and completed the present invention. came to.

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
An electrocatalyst comprising a catalyst on a carbon substrate,
The catalyst is an electrode catalyst containing a composite compound containing one metal element M selected from the group consisting of Zn, Cu, Ni, Mn, Fe and Cr, V and Co as constituent elements.
Item 2
Item 2. The electrode catalyst according to item 1, wherein the composite compound contains the metal element M, VO _x (where x is a number of 2 or more and 3 or less), and Co.
Item 3
3. A method for producing an electrode catalyst according to Item 1 or 2,
A method for producing an electrode catalyst, comprising a step of immersing a carbon substrate in a solution containing a metal element M source, a V source, and a Co source to perform electrodeposition treatment.
Item 4
Item 3. An electrode for hydrogen production, comprising the electrode catalyst according to Item 1 or 2.
Item 5
Item 5. A method for producing hydrogen, comprising the step of performing electrolytic treatment using the electrode according to item 4.

The electrode catalyst according to the present invention can be used as an electrode for hydrogen production, and exhibits a low overvoltage, a small Tafel slope, and excellent long-term stability during hydrogen production.

FIG. 4 is an SEM image of the surface of the electrode catalyst prepared in Example 1 and each comparative example. FIG. (a) is the measurement result of linear sweep voltammetry using the electrode catalysts prepared in Example 1 and each comparative example, (b) is the overvoltage at 10 mA cm ^-2 measured from the linear sweep voltammetry curve shown in (a) and Bar graph showing overvoltage at 50 mA cm ⁻² , (c) is a graph showing the Tafel slope calculated from the linear sweep voltammetry curve shown in (a). (a) shows a multi-current step chronopotentiometry curve of the electrode catalyst obtained in Example 1, and (b) shows a chronopotentiometry curve of the electrode catalyst obtained in Example 1. FIG. (a) is the measurement result of linear sweep voltammetry using the electrode catalysts prepared in Examples 1 to 4, and (b) is a graph showing the Tafel slope calculated from the linear sweep voltammetry curve shown in (a).

1. Electrode catalyst The electrode catalyst of the present invention comprises a catalyst on a carbon substrate, and the catalyst contains one metal element M selected from the group consisting of Zn, Cu, Ni, Mn, Fe and Cr. , V (vanadium) and Co (cobalt) as constituent elements. Such an electrode catalyst can be suitably used as an electrode for hydrogen production. Specifically, the electrode catalyst according to the present invention can reduce the overvoltage during hydrogen production, has a small Tafel slope, and is excellent in long-term stability.

The carbon substrate is a substrate for supporting the composite compound, and its type is not particularly limited, and examples thereof include a wide range of known carbon substrates. Specific examples of carbon substrates include carbon paper, carbon fiber paper, and carbon rods.

The carbon base material can be obtained, for example, by a known production method, or can be obtained from commercial products and the like. The shape and size of the electrode substrate are not particularly limited, and can be appropriately selected depending on the purpose of use and required performance. For example, the shape of the carbon substrate can be fibrous, sheet-like, plate-like, rod-like, mesh-like, and the like.

The composite compound is formed on the carbon substrate. Such a composite compound contains metal elements M, V (vanadium), and Co (cobalt), as described above.

The metal element M is one selected from the group consisting of Zn, Cu, Ni, Mn, Fe, and Cr. Among them, the metal element M is particularly preferably Zn (zinc). In this case, the electrode catalyst can have a particularly low overvoltage during hydrogen production, a particularly small Tafel slope, and a particularly excellent long-term stability of the electrode catalyst.

As long as the composite compound contains the metal elements M, V, and Co, the form of the compound is not particularly limited. The composite compound contains the metal element M, VO _x (where x is a number of 2 or more and 3 or less), and Co in that the overvoltage during hydrogen production can be made lower. and more preferably, the composite compound is an alloy of the metal element M, _VOx , and Co. In such alloys, the metallic elements M and Co are 0-valent.

The content ratio of the metal elements M, V and Co in the composite compound is not particularly limited. For example, the content of Co is preferably 80 to 99 mol%, more preferably 85 to 98 mol%, and even more preferably 90 to 97 mol%, relative to the total amount of the composite compound. . Further, the content of V is preferably 0.5 to 10 mol%, more preferably 1 to 7.5 mol%, and 1.5 to 5 mol% with respect to the total amount of the composite compound. is more preferable. The content of the metal element M is preferably 0.5 to 10 mol%, more preferably 1 to 7.5 mol%, more preferably 1.5 to 5 mol%, relative to the total amount of the composite compound. More preferably, it is mol %.

In the electrode catalyst of the present invention, the catalyst formed on the carbon substrate may contain elements, compounds, etc. other than the composite compound as long as the effects of the present invention are not inhibited. The catalyst preferably contains 80% by mass or more of the composite compound, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The catalyst can also be formed solely from the composite compound.

In the electrode catalyst of the present invention, the catalyst formed on the carbon substrate contains the composite compound, so that the overvoltage during hydrogen production can be reduced, the Tafel slope can be reduced, and , the long-term stability can also be smaller.

In the electrode catalyst of the present invention, the shape of the catalyst is not particularly limited. For example, the catalyst is preferably in the form of a thin film. That is, the catalyst is preferably formed as a thin film on the carbon substrate. The thickness of such a thin film is not particularly limited, and can be, for example, 0.1 to 100 μm. Among them, a nanosheet shape is particularly preferred. When the catalyst is in the form of a nanosheet, its thickness is 10-2000 nm, preferably 100-1000 nm, more preferably 200-500 nm. The catalyst can coat part or all of the carbon substrate. If the carbon substrate is fibrous, the catalyst may be formed over the fibers.

In the electrode catalyst of the present invention, when the catalyst is formed in the form of a thin film, the thin film can also have a porous structure. In addition, the thin film can have a laminated structure as well as a single layer structure.

In particular, since the electrode catalyst of the present invention contains a composite compound doped with the metal element M, the metal element M is easily distributed uniformly in the catalyst, and the growth of the porous structure is easily promoted. , excellent catalytic performance can be expressed. Although not necessarily wishing to be interpreted in a limiting sense, the complex compound has a strong interaction between Co and vanadium oxide (VO _x ) clusters, as well as the doped metal element M, which allows the crystal structure, electronic structure, and coordination environment is further tuned on an atomic scale, and as a result, catalysts containing complex compounds can exhibit superior performance.

The most preferred composite compound in the electrode catalyst of the present invention contains a composite compound in which a VO _x —Co composite compound is doped with Zn (zinc). Zn forms an alloy with the VO _x —Co complex compound.

The electrode catalyst of the present invention may be formed of only the carbon base material and the catalyst, or may be combined with other materials as long as the effects of the present invention are not impaired. The electrode catalyst can be formed, for example, directly on the carbon substrate (without passing through another layer or the like). In the electrode catalyst, it is preferred that no layer is formed on the catalyst.

Therefore, the electrode catalyst of the present invention is suitable for use in various electrolysis electrodes, and in particular, when used as an electrode for water electrolysis, it can bring about excellent hydrogen generation efficiency. Suitable for use in electrodes for

2. Method for producing an electrode catalyst The electrode catalyst of the present invention can be produced, for example, by immersing a carbon substrate in a solution containing the metal element M source, V source (vanadium source) and Co (cobalt source) source to subject it to electrodeposition treatment. It can be obtained by a manufacturing method comprising Hereinafter, such a step is referred to as "step 1". The metal element M source, V source and Co source used in step 1 are raw materials for the composite compound in the electrode catalyst of the present invention.

The carbon substrate used in step 1 is the same as the carbon substrate in the electrode catalyst of the present invention.

In the metal element M source, the metal element M is the same as the metal element M in the composite compound. Therefore, in the metal element M source, the metal element M is one selected from the group consisting of Zn, Cu, Ni, Mn, Fe, and Cr. Among them, the metal element M is particularly preferably Zn (zinc). .

The metal element M source is exemplified by, for example, a single metal element M or a compound containing the metal element M, and a compound containing the metal element M is preferable.

The type of compound containing the metal element M is not particularly limited. For example, as the compound containing the metal element M, inorganic acid salts of the metal element M, organic acid salts of the metal element M, hydroxides of the metal element M, halides of the metal element M, and the like can be widely used. .

As the inorganic acid salt of the metal element M, a wide range of known compounds can be employed, such as nitrates, hydrochlorides, sulfates, carbonates, hydrogencarbonates, phosphates and hydrogenphosphates of the metal element M 1 or more selected from the group consisting of and the like. As the inorganic acid salt of the metal element M, a sulfate salt of the metal element M (for example, ZnSO ₄ ) is preferable in terms of facilitating the production of the electrode catalyst.

As the organic acid salt of the metal element M, a wide range of known compounds can be employed, for example, one or more selected from the group consisting of acetates, oxalates, formates, succinates, etc. can be mentioned.

The metal element M sources used in step 1 may be used singly or in combination of two or more. A compound containing the metal element M can be obtained by a known production method, or a commercially available compound containing the metal element M can be used.

The V source (vanadium source) used in step 1 is not particularly limited as long as it contains V (vanadium).

The type of compound containing V is not particularly limited. For example, as compounds containing V, inorganic acid salts of V, compounds containing oxoanions of V (metallic acid salts), organic acid salts of V, hydroxides of V and halides of V are widely used. be able to.

As the inorganic acid salt of V, a wide range of known compounds can be employed, for example, the group consisting of nitrates, hydrochlorides, sulfates, carbonates, hydrogen carbonates, phosphates and hydrogen phosphates of V. One or more selected from can be mentioned.

Examples of compounds containing an oxo anion of V include orthoacid salts of V, metaacid salts of V, and the like. Specific examples include vanadates, such as ammonium vanadate (NH ₄ VO ₃ ).

As the organic acid salt of V, a wide range of known compounds can be employed, for example, one or more selected from the group consisting of V acetate, oxalate, formate, succinate, etc. can.

The V sources used in step 1 may be used singly or in combination of two or more. A compound containing V can be obtained by a known production method, or a commercially available compound containing V can also be used.

The Co source (cobalt source) used in step 1 is not particularly limited as long as it contains Co (cobalt).

The type of Co-containing compound is not particularly limited. For example, as the Co-containing compound, an inorganic acid salt of Co, an organic acid salt of Co, a hydroxide of Co, a halide of Co, and the like can be widely used.

As the inorganic acid salt of Co, a wide range of known compounds can be employed. One or more selected from can be mentioned. Co sulfate (for example, CoSO ₄ ) is preferable as the inorganic acid salt of Co in terms of facilitating the production of the electrode catalyst.

As the organic acid salt of Co, a wide range of known compounds can be employed, and examples include one or more selected from the group consisting of Co acetate, oxalate, formate, succinate, and the like. can.

The Co source used in step 1 may be used singly or in combination of two or more. The Co-containing compound can be obtained by a known production method, or a commercially available Co-containing compound can be used.

In step 1, a solution containing the metal element M source, V source and Co source is used. The method for preparing this solution is not particularly limited, and for example, it can be prepared by mixing the metal element M source, V source and Co source with a solvent in a predetermined ratio. The solvent is not particularly limited, and examples thereof include water, and a mixed solvent of water and a lower alcohol compound may also be used.

The concentration of raw materials in the solution is not particularly limited. From the viewpoint of excellent solubility and reactivity of the raw materials, it is preferable to use the solvent so that the concentrations of the metal element M source, V source and Co source are 1 mM to 1M. More specifically, the concentration of the metal element M source in the solution is preferably 1-100 mM, more preferably 3-50 mM. Also, the concentration of the V source in the solution is preferably 1 to 100 mM, more preferably 3 to 50 mM. Also, the concentration of the Co source in the solution is preferably 50-1000 mM, more preferably 100-600 mM.

The contents of the metal elements M, V and Co in the solution are not particularly limited. For example, the content of Co is preferably 80 to 99 mol%, more preferably 85 to 98 mol%, more preferably 90 to 97%, based on the total amount of the metal elements M, V and Co in the solution. More preferably, it is mol %. Further, the content of V is preferably 0.5 to 10 mol%, more preferably 1 to 7.5 mol%, and 1.5 to 5 mol% with respect to the total amount of the composite compound. is more preferable. The content of the metal element M is preferably 0.5 to 10 mol%, more preferably 1 to 7.5 mol%, more preferably 1.5 to 5 mol%, relative to the total amount of the composite compound. More preferably, it is mol %.

The solution may appropriately contain additives such as pH adjusters. When the solution contains a pH adjuster, the pH of the solution is stabilized, so hydrolysis of the Co source (for example, cobalt sulfate) is easily suppressed, and the electrodeposition treatment can be performed more stably. The type of pH adjuster is not particularly limited, and a wide range of known pH adjusters such as H ₃ BO ₄ can be used.

In step 1, the method of electrodeposition treatment is not particularly limited, and for example, a wide range of known electrodeposition methods can be employed. For example, a carbon substrate can be immersed in the solution to carry out electrodeposition treatment.

Various electrodeposition methods can be mentioned as the electrodeposition treatment. Electrodeposition methods include constant current method (GM), constant voltage method (PM), cyclic voltammetry method (CV), pulse electrodeposition method and the like. The pulse electrodeposition method is an electrodeposition method that can control the electrodeposition speed of metal ions. A pulse current method (PGM) in which a current is applied at a constant cycle, and a unipolar pulse voltage method (UPED) in which a high end voltage and an open circuit state are repeatedly performed at a constant cycle.

Conditions for the electrodeposition treatment are also not particularly limited. For example, the applied voltage can be -2 to 2 V (preferably 1.5 to 2 V) and the electrodeposition time can be 100 to 2000 seconds (preferably 300 to 1800 seconds). The temperature of the solution during the electrodeposition treatment is not particularly limited, and can be, for example, about 0 to 50.degree. C., preferably 20 to 30.degree.

Electrodeposition can be performed using a carbon substrate as a cathode (working electrode). In the electrodeposition process, in addition to the cathode, a counter electrode, a reference electrode, an electrolytic device, a power supply, control software, etc. can be used. These types are not particularly limited, and known ones can be used depending on the purpose. For example, as a reference electrode, a silver/silver chloride electrode (Ag/AgCl electrode), a mercury/mercury chloride electrode (Hg/ _HgCl2 electrode), a standard hydrogen electrode, or the like can be used. A platinum wire can be used as the counter electrode.

By the electrodeposition treatment in step 1, the composite compound is formed on the carbon substrate to obtain the electrode catalyst of the present invention.

The manufacturing method of the present invention may have a configuration other than step 1, or may include only step 1. In other words, in the production method of the present invention, the intended electrode catalyst can be obtained without providing a step such as a calcination treatment after the electrodeposition treatment. Therefore, in the production method of the present invention, an electrode catalyst having excellent catalytic performance can be obtained while the steps are simpler than those of conventional methods.

3. Method for Producing Hydrogen The method for producing hydrogen of the present invention includes the step of performing electrolytic treatment using the electrode catalyst of the present invention. Alternatively, the method for producing hydrogen of the present invention includes a step of performing electrolytic treatment using the electrode catalyst obtained by the above-described method for producing an electrode catalyst of the present invention.

The method for producing hydrogen of the present invention can use an electrode catalyst, for example, as a cathode.

On the other hand, in the method for producing hydrogen of the present invention, an electrode that is generally used as an anode in the electrolysis of water can be used as the anode. For example, electrodes made of noble metals such as carbon, platinum, and gold can be used as cathodes.

In the method for producing hydrogen of the present invention, the aqueous solution used in electrolysis may be an aqueous solution containing components generally used in electrolysis of water. The aqueous solution may also contain halogens such as iodine, bromine, sulfate ions, and the like. When using an aqueous solution containing iodine, iodate ions are generated at the anode. The aqueous solution may be in the acidic range, the neutral range, or the alkaline range. For example, aqueous solutions such as KOH and NaOH can be used in the alkaline region, aqueous solutions such as hydrochloric acid and sulfuric acid can be used in the acidic region, and PBS (phosphate buffered saline) can be used in the neutral region. etc. can be used.

To give a specific example of the method for producing hydrogen, the electrode catalyst of the present invention is used as a cathode, a platinum plate is used as an anode, and KOH, H ₂ SO ₄ or a PBS aqueous solution is used as an electrolyte, and a voltage is applied. This allows hydrogen to be produced at the cathode. Also, by increasing the applied voltage, the rate of hydrogen generation can be increased.

Hydrogen produced by the method for producing hydrogen can be preferably used as fuel for fuel cells, hydrogen engines, and the like.

In the method for producing hydrogen of the present invention, since the electrode catalyst is used as an electrode, an increase in overvoltage is less likely to occur, and hydrogen can be produced efficiently.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

(Example 1)
As a carbon substrate, carbon paper (2×2 cm) was ultrasonically cleaned in a concentrated nitric acid solution for 1 hour, washed with ethanol and deionized water, and dried in a vacuum drying oven for 12 hours. Electrodeposition was carried out in solution by an electrochemical joining (anodization) process using a three-electrode system with the carbon substrate as the working electrode, a Pt wire as the counter electrode and Ag/AgCl as the reference electrode. rice field. The solution was prepared by mixing 50 mL of 0.5 M CoSO ₄ aqueous solution, 50 mL of 10 mM ZnSO ₄ aqueous solution, 50 mL of 10 mM NH ₄ VO ₃ aqueous solution and 50 mL of 0.5 M H ₃ BO ₃ aqueous solution. The electrodeposition conditions were room temperature (25° C.), −1.7 V (vs. RHE), and electrodeposition for 1200 seconds. By this electrodeposition treatment, a composite compound was formed on the carbon substrate to obtain the intended electrode catalyst. The obtained electrode catalyst was named "Zn--VO _x --Co" or "Zn--VO _x --Co-10". From the synthesis conditions and the working ratio, it was presumed that the obtained Zn-VO _x -Co was an alloy of Zn, VO _x and Co, where x was 2 or more and 3 or less.

(Example 2)
An electrode catalyst was obtained in the same manner as in Example 1, except that the concentration of the _ZnSO4 aqueous solution was changed to 5 mM. The obtained electrode catalyst was named "Zn-VO _x -Co-5".

(Example 3)
An electrode catalyst was obtained in the same manner as in Example 1, except that the concentration of the _ZnSO4 aqueous solution was changed to 8 mM. The obtained electrode catalyst was named "Zn-VO _x -Co-8".

(Example 4)
An electrode catalyst was obtained in the same manner as in Example 1, except that the concentration of the _ZnSO4 aqueous solution was changed to 12 mM. The obtained electrode catalyst was named "Zn-VO _x -Co-12".

(Comparative example 1)
An electrode catalyst carrying Co as a carbon base material was prepared.

(Comparative example 2)
An electrode catalyst supporting Zn—Co as a carbon substrate was prepared.

(Comparative Example 3)
An electrode catalyst supporting VO _x —Co of a carbon base material was prepared.

(Comparative Example 4)
An electrode catalyst supporting Zn—VO 2 _x as a carbon substrate was prepared.

FIG. 1 shows an SEM (Scanning Electron Microscope) image of the electrocatalyst surface. Specifically, FIG. 1 (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Comparative Example 3, (d), (e) and (f) are the electrodes obtained in Example 1. 1 is an SEM image of a catalyst surface, particularly a catalyst surface formed on a carbon substrate;

From FIG. 1, the electrode catalyst (Co) of Comparative Example 1 had a uniform nanosheet structure, and the electrode catalyst (Zn—Co) of Comparative Example 2 had the same structure (see FIGS. 1(a) and 1(b)). It was found that the electrode catalyst (VO _x —Co) of Comparative Example 3 was a two-dimensional nanosheet (FIG. 1(c)).

In contrast, the electrode catalyst (Zn—VO _x —Co) obtained in Example 1 was found to have large nanosheet growth and a uniform two-dimensional ultrathin structure (FIG. 2 ( d), (e) and (f)). It was confirmed that such ultrathin nanosheets have a multi-layered structure in which flakes with a major axis of about 1 to 3 μm are superimposed on each other. Therefore, the electrode catalyst obtained in Example 1 has a large active surface area and can provide more exposed active sites, thereby promoting ion migration in the electrolyte and improving catalytic performance. there were.

FIG. 2(a) shows the measurement results of linear sweep voltammetry (scan rate 2 mV/s, electrolytic solution 1 M KOH aqueous solution) using the electrode catalysts prepared in Example 1 and each comparative example. A linear sweep voltammetry curve was obtained by a hydrogen evolution (HER) test using a platinum plate as the cathode and an Ag/AgCl electrode as the reference electrode. The measurement equipment for obtaining linear sweep voltammetry curves used a US VersaSTAT4 potentiostat galvanostat electrochemical workstation with a standard three-electrode cell.

FIG. 2(b) is a bar graph showing overvoltages at 10 mA cm ⁻² (right bar graph in the figure) and 50 mA cm ⁻² (left bar graph in the figure) measured from the linear sweep voltammetry curve shown in (a), ( c) is a graph showing the Tafel slope calculated from the linear sweep voltammetry curve shown in (a).

Table 1 summarizes the results obtained in FIG. In the table, η ₁₀ and η ₅₀ indicate overvoltage (mV) at 10 mAcm ^-2 and 50 mAcm ^-2 respectively.

The Zn—VO _x —Co electrode catalyst obtained in Example 1 has a lower overvoltage than the electrode catalyst prepared in Comparative Example, and has the smallest Tafel slope, so it is expected to exhibit excellent activity. It became clear. The minimum Tafel slope suggests HER dynamics that follow the Volmer-Heyrovsky mechanism.

FIG. 3(a) is a multi-current step chronopotentiometric curve of the electrode catalyst obtained in Example 1, and (b) is a chronopotentiometry curve of the same electrode catalyst. These results show that the electrode catalyst obtained in Example 1 has excellent long-term stability and mechanical robustness.

FIG. 4(a) is the measurement result of linear sweep voltammetry using the electrode catalysts prepared in Examples 1 to 4, and (b) is a graph showing the Tafel slope calculated from the linear sweep voltammetry curve shown in (a). Yes (the measurement method is the same as in Fig. 2). From this result, it was found that the composite compound exhibits excellent catalytic action over a wide range of elemental compositions.

Claims (5)

An electrocatalyst comprising a catalyst on a carbon substrate,
The catalyst is an electrode catalyst containing a composite compound containing one metal element M selected from the group consisting of Zn, Cu, Ni, Mn, Fe and Cr, V and Co as constituent elements. The electrode catalyst according to claim 1, wherein the composite compound contains the metal element M, VOx (where _x is a number of 2 or more and 3 or less), and Co. A method for producing the electrode catalyst according to claim 1 or 2,
A method for producing an electrode catalyst, comprising a step of immersing a carbon substrate in a solution containing a metal element M source, a V source, and a Co source to perform electrodeposition treatment. An electrode for hydrogen production, comprising the electrode catalyst according to claim 1 or 2. A method for producing hydrogen, comprising the step of performing an electrolytic treatment using the electrode according to claim 4.

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