Electrode for hydrogen evolution and manufacturing method therefor

Abstract

The present invention relates to an electrode for hydrogen evolution and a manufacturing method therefor, the electrode comprising a molybdenum-ruthenium-titanium composite oxide layer formed on a porous titanium metal substrate.

Description

Electrode for hydrogen generation and method for manufacturing the same

[0001] This invention claims the benefit of Korean Patent Application No. 10-2023-0118283 filed with the Korean Intellectual Property Office on September 6, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode for hydrogen generation comprising molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate and a method for manufacturing the same.

[0003]

[0004] Hydrogen is attracting significant attention as a clean, carbon-free next-generation energy source. Until now, hydrogen has primarily been produced through steam reforming, which presents a contradiction because it still relies on environmentally unfriendly fossil fuels. Therefore, active research is being conducted on alternative production technologies that can produce hydrogen in an environmentally friendly manner. One such method involves producing high-purity hydrogen through water electrolysis.

[0005] However, considering the high cost of electrodes (catalysts) used to reduce the energy required for water electrolysis, there is still considerable room for development. Research to replace these expensive catalysts with less expensive materials has resulted in numerous reports of sulfide and carbide catalysts based on transition metals (nickel, molybdenum, iron, and cobalt). Recently, phosphide-based transition metals have been widely reported as hydrogen-producing catalysts, demonstrating relatively high activity compared to other non-precious metal catalysts.

[0006] Catalysts used in electrolysis reactions must not only exhibit high reaction activity, but also possess long-term stability, which is a prerequisite. However, research on non-precious metal catalysts has focused on enhancing their activity. Consequently, relatively little research has been conducted on catalyst durability, and their activity has been significantly lower than that of platinum-based catalysts.

[0007] In particular, platinum is the material commonly used as the current hydrogen generation reaction electrode, but it has the disadvantage of requiring high costs for electrode manufacturing due to its high price, and has the disadvantage of low activity under alkaline electrolyte conditions with high pH.

[0008] Therefore, research is needed on hydrogen-generating electrodes that can be manufactured at low cost and have high stability.

[0009]

[0010] The technical problem to be achieved by the present invention is to provide an electrode for hydrogen generation having excellent stability and electrochemical properties and a method for easily manufacturing the same.

[0011] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0012]

[0013] According to one aspect of the present invention, there is provided a hydrogen generation electrode comprising: a porous titanium metal substrate; a titanium dioxide layer formed on the porous titanium metal substrate and having a nano-sized surface roughness and doped with molybdenum; and a plurality of molybdenum-ruthenium-titanium composite oxide particles positioned on the molybdenum-doped titanium dioxide layer, wherein the molybdenum-ruthenium-titanium composite oxide particles comprise a ruthenium dioxide core; and a molybdenum-doped titanium dioxide shell.

[0014] The above molybdenum-ruthenium-titanium composite oxide particle is characterized in that, during a hydrogen evolution reaction, the ruthenium (Ru) dioxide of the core is reduced to ruthenium (Ru) metal, the molybdenum-doped titanium dioxide of the shell is reduced to porous titanium, and the molybdenum atoms doped in the titanium dioxide are present at the interface between the ruthenium metal core and the porous reduced titanium shell.

[0015] Another embodiment of the present invention provides a method for manufacturing an electrode for hydrogen generation, comprising: a step of forming a titanium dioxide layer on a surface of a porous titanium metal substrate by oxidizing the porous titanium metal substrate having the titanium dioxide layer formed thereon; a step of coating a molybdenum precursor solution on the porous titanium metal substrate having the titanium dioxide layer formed thereon and then performing a first hydrothermal reaction to manufacture a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon; a step of coating a ruthenium precursor solution on the porous titanium metal substrate having the molybdenum-doped titanium dioxide layer formed thereon and then performing a second hydrothermal reaction to form a plurality of ruthenium dioxide particles embedded in the molybdenum-doped titanium dioxide layer; and a step of heat-treating the porous titanium metal substrate having the molybdenum-doped titanium dioxide layer having the ruthenium dioxide particles embedded therein.

[0016]

[0017] An electrode for hydrogen generation comprising molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate according to one embodiment of the present invention has excellent electrochemical properties and can exhibit excellent stability and hydrogen generation efficiency.

[0018] That is, when platinum is used as an electrode for hydrogen generation, the hydrogen generation efficiency may decrease because the reaction rate for decomposing water in an alkaline electrolyte is slow.

[0019] On the other hand, since the electrode for hydrogen generation according to one embodiment of the present invention includes molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate, it has excellent electrochemical properties and can have excellent stability and hydrogen generation efficiency.

[0020] Specifically, ruthenium has a very good rate of reaction to decompose water, but has the disadvantage of low stability as the reaction progresses.

[0021] In the present invention, high stability can be secured by synthesizing core-shell nanoparticles that form a single layer of titanium dioxide doped with molybdenum on the outside of ruthenium dioxide metal nanoparticles while maintaining the excellent performance of ruthenium.

[0022] In addition, a method for manufacturing a hydrogen generation electrode including molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate according to one embodiment of the present invention can easily manufacture a hydrogen generation electrode having excellent stability and electrochemical properties.

[0023] However, the effects of the present invention are not limited to the above-described effects, and may be expanded in various ways without departing from the spirit and scope of the present invention.

[0024]

[0025] FIG. 1a is a schematic diagram of a molybdenum-ruthenium-titanium composite oxide particle structure according to one embodiment of the present invention, and FIG. 1b is a schematic diagram of a molybdenum-ruthenium-titanium composite oxide particle structure according to one embodiment of the present invention during a hydrogen generation reaction.

[0026] FIG. 2a is LSV data measuring the hydrogen generation performance of each hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2b is Tafel plot data of the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2c is data measuring the electrochemical specific surface area of ​​the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2d is data measuring the charge transfer resistance and exchange current density of the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2e is a graph showing the mass activity (data obtained by dividing the current density by the mass of ruthenium) of the example 2 of the present invention and the comparative example, FIG. 2f is a graph comparing the performance of the alkaline condition hydrogen generation electrode with the example 2 of the present invention, and FIG. 2g is a graph comparing the performance of the alkaline condition hydrogen generation electrode with the time of the example and the comparative example at 100 mA cm -2 This is the data of the change in overvoltage at the current density, and Fig. 2h shows the data of 100 mA cm of the example and comparative example. -2 ICP-MS data at current density, and Fig. 2i is 100 mA cm -2 This is a graph measuring the stability of Example 2 at current density.

[0027] FIG. 3a is a HAADF-STEM image before the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, FIG. 3b is an image regarding the line-scan measurement result of a sample before the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, FIG. 3c is an XPS image before and after the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, FIG. 3d is a TEM image after the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, FIG. 3e is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image after the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, FIG. 3f is an electron energy loss spectrum (EELS) image of a sample after the electrochemical reaction of the hydrogen-generation electrode manufactured in Example 2 of the present invention, and FIG. 3g is an image of a line-scan measurement by dividing atoms of Example 2 into 5 regions after the electrochemical reaction.

[0028] FIG. 4 is a graph showing the performance of an anion exchange membrane electrolysis (AEMWE) process using the hydrogen generation electrode manufactured in Example 2 of the present invention. FIG. 4a is a schematic diagram of the reactor of AEMWE, FIG. 4b is a performance comparison graph of a water electrolysis system using the hydrogen generation electrode manufactured in Example 2 of the present invention and iridium dioxide, a commercial electrode, as an anode electrode (oxygen evolution reaction), and a water electrolysis system using a platinum / carbon electrode and iridium dioxide electrode, which are commercial electrodes, FIG. 4c is a performance comparison table between the hydrogen generation electrode manufactured in Example 2 of the present invention and electrodes reported so far, FIG. 4d is data analyzing the contribution to electrode performance, FIG. 4e is data measuring the stability of Example 2 at a current density of 500 mA, and FIG. 4f is a graph evaluating the hydrogen generation reaction performance once again using the hydrogen generation electrode manufactured in Example 2 of the present invention, which completed the stability measurement of FIG. 4e.

[0029]

[0030] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0031] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0032] Throughout this specification, at% may represent atomic percentage, wt% may represent weight percentage or parts by weight, and mol% may represent mole percentage.

[0033]

[0034] The specific details for implementing the present invention will be described in detail with reference to the attached drawings below.

[0035] According to one aspect of the present invention, there is provided a hydrogen generation electrode comprising: a porous titanium metal substrate; a titanium dioxide layer formed on the porous titanium metal substrate and having a nano-sized surface roughness and doped with molybdenum; and a plurality of molybdenum-ruthenium-titanium composite oxide particles positioned on the molybdenum-doped titanium dioxide layer, wherein the molybdenum-ruthenium-titanium composite oxide particles comprise a ruthenium dioxide core; and a molybdenum-doped titanium dioxide shell.

[0036] Fig. 1a is a schematic diagram of an electrode for hydrogen generation according to one embodiment of the present invention. Referring to Fig. 1a, a plurality of molybdenum-ruthenium-titanium composite oxide particles, each composed of a ruthenium dioxide core (2) and a molybdenum-doped titanium dioxide shell (3), are positioned on a molybdenum-doped titanium dioxide layer (1) on a porous titanium metal substrate.

[0037] In Fig. 1a, only the molybdenum-ruthenium-titanium composite oxide particle portion is enlarged, and the molybdenum-ruthenium-titanium composite oxide particle may be embedded in a molybdenum-doped titanium dioxide layer (1) having a nano-sized surface roughness. Here, the embedded may include a case where the molybdenum-ruthenium-titanium composite oxide particle is partially or completely embedded in the molybdenum-doped titanium dioxide layer having a nano-sized surface roughness.

[0038] An electrode for hydrogen generation according to one embodiment of the present invention may have excellent stability and excellent electrochemical properties. Specifically, when the electrode for hydrogen generation is utilized, the hydrogen generation efficiency may be excellent. In addition, the molybdenum-ruthenium-titanium composite oxide particles may have excellent resistance to cathodic corrosion. Specifically, since a titanium dioxide shell doped with molybdenum is formed on the ruthenium dioxide core, the dissolution of the ruthenium particles may be effectively suppressed when applied as a hydrogen generation electrode. In addition, by doping molybdenum into the titanium dioxide on the surface of the porous titanium metal substrate, the electronic conductivity of the electrode for hydrogen generation can be improved, and the hydroxylation of titanium dioxide can be effectively suppressed, thereby maintaining excellent electrochemical properties for a long period of time. In addition, the electrode for hydrogen generation may have excellent price competitiveness because it contains a very small amount of expensive ruthenium.

[0039] FIG. 1b is a schematic diagram showing changes in molybdenum-ruthenium-titanium composite oxide particles of a hydrogen generation electrode according to an embodiment of the present invention during a hydrogen generation reaction. Referring to FIG. 1b, during a hydrogen generation reaction, ruthenium dioxide (Ru) (2) of the core is reduced to ruthenium (Ru) metal (2`), and the molybdenum-doped titanium dioxide (3) of the shell is changed into porous titanium (3`) as the titanium dioxide is reduced, and molybdenum atoms (4) exist at the interface between the ruthenium metal core (2`) and the porous titanium shell (3`).

[0040] When the above molybdenum-ruthenium-titanium composite oxide particles undergo a hydrogen generation reaction, the ruthenium dioxide (Ru) (2) of the core is reduced to ruthenium (Ru) metal (2`), the molybdenum-doped titanium dioxide (3) of the shell is transformed into porous titanium (3`) as the titanium dioxide is reduced, and the molybdenum atoms (4) exist at the interface between the ruthenium metal core (2`) and the porous titanium shell (3`), so that the hydrogen generation efficiency can be excellent.

[0041] According to one embodiment of the present invention, the shell is a single layer, and the thickness of the shell may be 1 Å or more and 8 Å or less. Specifically, it may be 2 Å or more and 7 Å or less, 2 Å or more and 6 Å or less, or 1 Å or more and 6 Å or less. Molybdenum-ruthenium-titanium composite oxide particles having a molybdenum-doped titanium dioxide shell having a thickness within the above-described range can exhibit excellent resistance to cathodic corrosion and excellent electrochemical properties.

[0042] According to one embodiment of the present invention, the average particle diameter of the molybdenum-ruthenium-titanium composite oxide particles formed on the porous titanium metal substrate may be 1.0 nm or more and 3.0 nm or less. Specifically, it may be 1.1 nm or more and 2.9 nm or less, 1.2 nm or more and 2.8 nm or less, 1.3 nm or more and 2.7 nm or less, 1.4 nm or more and 2.8 nm or less, 1.5 nm or more and 2.5 nm or less, 1.5 nm or more and 2.7 nm or less, or 1.4 nm or more and 2.6 nm or less. The molybdenum-ruthenium-titanium composite oxide particles formed on the porous titanium metal substrate having an average particle diameter in the above-described range can implement excellent resistance to cathodic corrosion and excellent electrochemical properties.

[0043] According to one embodiment of the present invention, the thickness of the molybdenum-doped titanium dioxide layer formed on the surface of the porous titanium metal substrate may be 30 nm or more and 50 nm or less. Specifically, it may be 32 nm or more and 48 nm or less, 34 nm or more and 46 nm or less, 36 nm or more and 44 nm or less, 38 nm or more and 42 nm or less, 36 nm or more and 42 nm or less, 38 nm or more and 46 nm or less, or 38 nm or more and 40 nm or less. By satisfying the above thickness range, excellent resistance to cathodic corrosion and excellent electrochemical properties can be realized.

[0044] According to one embodiment of the present invention, the molybdenum-ruthenium-titanium composite oxide particles have a unit surface area of ​​1 cm of the porous titanium metal substrate. 2It may contain 0.0001g or more and 0.0003g or less of ruthenium. Specifically, it may be 0.00011g or more and 0.00028g or less, 0.00012g or more and 0.00026g or less, 0.00011g or more and 0.0024g or less, 0.00013g or more and 0.00022g or less, 0.00014g or more and 0.00020g or less, 0.00013g or more and 0.00018g or less, 0.00014g or more and 0.00016g or less, or 0.000013g or more and 0.00016g or less. By satisfying the above range, electrochemical properties can be effectively improved. In addition, the cost of the process can be reduced by containing a smaller amount of ruthenium compared to a conventional DSA commercial catalyst electrode.

[0045] According to one embodiment of the present invention, the porous titanium metal substrate may be in the form of a foam. The porous titanium metal substrate in the form of a foam may facilitate molybdenum doping and formation of ruthenium dioxide particles, and may have excellent compatibility with the molybdenum precursor and the ruthenium precursor.

[0046] According to one embodiment of the present invention, the pores of the porous titanium metal substrate may have an average particle diameter of 10 μm or more and 50 μm or less. When a porous titanium metal substrate having pores with an average particle diameter within the above-described range is used, molybdenum doping and formation of ruthenium dioxide particles can be facilitated, and the electrochemical properties of the electrode for hydrogen generation can be further improved.

[0047] According to one embodiment of the present invention, a method for manufacturing an electrode for hydrogen generation according to one embodiment of the present invention is provided, comprising: a step of forming a titanium dioxide layer on a surface of a porous titanium metal substrate by oxidizing the porous titanium metal substrate having the titanium dioxide layer formed thereon; a step of coating a molybdenum precursor solution on the porous titanium metal substrate having the titanium dioxide layer formed thereon and then performing a first hydrothermal reaction to manufacture a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon; a step of coating a ruthenium precursor solution on the porous titanium metal substrate having the molybdenum-doped titanium dioxide layer formed thereon and then performing a second hydrothermal reaction to form a plurality of ruthenium dioxide particles embedded in the molybdenum-doped titanium dioxide layer; and a step of heat-treating the porous titanium metal substrate having the molybdenum-doped titanium dioxide layer having the ruthenium dioxide particles embedded therein.

[0048] A method for manufacturing a hydrogen generation electrode according to one embodiment of the present invention can easily manufacture a hydrogen generation electrode having excellent stability and electrochemical properties.

[0049] Hereinafter, a method for manufacturing an electrode for hydrogen generation according to an embodiment of the present invention will be described in detail step by step.

[0050] According to one embodiment of the present invention, a titanium dioxide layer having nano-sized surface roughness is formed on the surface of a porous titanium metal substrate by oxidizing the substrate. By forming a titanium dioxide layer having nano-sized surface roughness on the surface of the substrate, the surface area of ​​the electrode can be increased.

[0051] Specifically, by forming a titanium dioxide layer, which is an oxide layer, on the surface of a porous titanium metal substrate, it is possible to have a nano-sized surface roughness, thereby increasing the surface area compared to a conventional flat substrate.

[0052] According to one embodiment of the present invention, a titanium metal substrate can be oxidized using hydrogen peroxide (H2O2) to form a titanium dioxide layer on the surface. When hydrogen peroxide is used, the titanium metal is easily ionized and forms a concave surface shape on the surface of the titanium metal substrate, thereby forming a nano-sized surface roughness, and thus can provide high roughness. When the surface of the titanium metal substrate has high roughness, a larger amount of molybdenum can be doped during molybdenum doping, and further, a larger amount of ruthenium dioxide particles can be formed on the molybdenum-doped titanium dioxide layer.

[0053] According to one embodiment of the present invention, the concentration of the hydrogen peroxide may be 40 wt% or more and 60 wt% or less. Specifically, it may be 42 wt% or more and 58 wt% or less, 46 wt% or more and 56 wt% or less, 48 ​​wt% or more and 54 wt% or less, 48 ​​wt% or more and 52 wt% or less, 46 wt% or more and 52 wt% or less, or 46 wt% or more and 50 wt% or less. When the concentration range of the hydrogen peroxide is satisfied, the titanium metal is more easily ionized and a concave surface shape is more easily formed on the surface of the titanium metal substrate, thereby forming nano-sized surface roughness and imparting high roughness.

[0054] According to one embodiment of the present invention, the step of forming a titanium dioxide layer on the surface of the porous titanium metal substrate by oxidizing the substrate may be, for example, performed by immersing the substrate in hydrogen peroxide at a temperature of 50°C or more and 90°C or less for 20 minutes or more and 40 minutes or less. Specifically, it may be performed at a temperature of 55°C or more and 85°C or less, 60°C or more and 80°C or less, 65°C or more and 75°C or less, 60°C or more and 70°C or less, or 65°C or more and 80°C or less for 23 minutes or more and 37 minutes or less, 26 minutes or more and 34 minutes or less, 29 minutes or more and 31 minutes or less, 26 minutes or more and 31 minutes or less, or 29 minutes or more and 34 minutes or less. When the temperature and time ranges for forming a titanium dioxide layer on the surface of the porous metal substrate by oxidizing the substrate are satisfied, a concave surface shape can be more easily created, thereby forming a structure having nano-sized surface roughness.

[0055] Next, a molybdenum precursor solution is coated on a porous titanium metal substrate having a titanium dioxide layer formed on the surface, and then a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon is manufactured through a first hydrothermal reaction. By doping molybdenum into the titanium metal substrate having nano-sized surface roughness formed on the surface by oxidation and a titanium dioxide layer formed thereon, the heat treatment temperature for forming molybdenum-ruthenium-titanium composite oxide particles can be lowered, and the molybdenum-ruthenium-titanium composite oxide particle layer can be effectively suppressed from dissolving when used as an electrode for hydrogen generation. In addition, by doping molybdenum into the porous titanium metal substrate to form a molybdenum-doped titanium dioxide layer on the surface of the substrate, the electronic conductivity of the electrode for hydrogen generation can be improved, and the hydroxylation of titanium dioxide can be effectively suppressed, so that better electrochemical properties can be maintained for a long period of time.

[0056] A material capable of doping molybdenum into a titanium dioxide layer of a porous titanium metal substrate having a titanium dioxide layer formed on the surface thereof may be used as a precursor. Specifically, the molybdenum precursor may include a molybdenum halide. For example, the molybdenum halide may include at least one of MoF5, MoCl5, MoBr5, and MoI5. More specifically, in terms of solubility and thermal stability, the molybdenum halide may include MoCl5. By using the molybdenum precursor including a molybdenum halide, molybdenum can be more stably and effectively doped into the titanium dioxide layer formed on the surface of the porous titanium metal substrate.

[0057] According to one embodiment of the present invention, the molybdenum precursor solution may have a content of the molybdenum precursor of 0.005 mol% or more and 0.015 mol% or less. Specifically, the content of the molybdenum precursor contained in the molybdenum precursor solution may be 0.006 mol% or more and 0.014 mol%, 0.007 mol% or more and 0.013 mol%, 0.008 mol% or more and 0.012 mol%, 0.009 mol% or more and 0.011 mol%, 0.008 mol% or more and 0.011 mol%, or 0.010 mol% or more and 0.012 mol% or less. When the content of the molybdenum precursor contained in the molybdenum precursor solution is within the above-mentioned range, molybdenum can be stably doped into the titanium dioxide layer formed on the surface of the titanium metal substrate. In addition, by adjusting the content of the molybdenum precursor contained in the molybdenum precursor solution within the above-described range, the molybdenum content of the electrode for hydrogen generation can be appropriately adjusted as described below, thereby further improving the stability and electrochemical properties of the electrode.

[0058] According to one embodiment of the present invention, a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon can be manufactured more easily through the first hydrothermal reaction, thereby effectively reducing the cost required for the entire process of manufacturing an electrode for generating hydrogen. That is, through the method according to one embodiment of the present invention, an electrode for generating hydrogen comprising a molybdenum-ruthenium-titanium composite oxide particle layer formed on a porous titanium metal substrate having excellent price competitiveness can be manufactured.

[0059] According to one embodiment of the present invention, the first hydrothermal reaction can be performed at a temperature of 150°C or more and 200°C or less for a time of 5 hours or more and 8 hours or less. Specifically, the temperature at which the first hydrothermal reaction is performed may be 160°C or more and 190°C or less, 170°C or more and 180°C or less, 150°C or more and 180°C or less, or 160°C or more and 200°C or less. In addition, the time at which the first hydrothermal reaction is performed may be 6 hours or more and 7 hours or less, 5 hours or more and 7 hours or less, or 6 hours or more and 8 hours or less. By controlling the temperature and time at which the first hydrothermal reaction is performed within the above-mentioned range, molybdenum can be more stably and efficiently doped onto the porous titanium metal substrate on which the titanium dioxide layer is formed.

[0060] According to one embodiment of the present invention, the first hydrothermal reaction may be performed at a heating rate of 5°C / min to 15°C / min, 7°C / min to 13°C / min, 5°C / min to 10°C / min, or 10°C / min to 15°C / min within the above-mentioned temperature range. When the heating rate of the molybdenum precursor solution is within the above-mentioned range, the application of thermal shock to the reactants is prevented, thereby allowing molybdenum to be doped more stably and efficiently on the surface of the porous titanium metal substrate on which the titanium dioxide layer is formed.

[0061] An additional step of drying in a vacuum oven may be included before forming ruthenium dioxide particles on a porous titanium substrate having a molybdenum-doped titanium dioxide layer formed thereon. For example, drying in a vacuum oven may be performed for about 24 hours.

[0062] In the next step, a ruthenium precursor solution is coated on the porous titanium metal substrate on which the molybdenum-doped titanium dioxide layer is formed, and then ruthenium dioxide particles are formed through a second hydrothermal reaction.

[0063] According to one embodiment of the present invention, the ruthenium precursor solution may include a ruthenium halide. For example, the ruthenium halide may include at least one of RuF3, RuCl3, RuBr3, and RuI3. Specifically, the ruthenium halide may include RuCl3 in terms of solubility and thermal stability. By using the ruthenium precursor including a ruthenium halide, ruthenium dioxide particles can be effectively formed. Through this, a hydrogen generation electrode including molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate can be stably manufactured. In addition, the ruthenium precursor may be a hydrate. By using the ruthenium precursor in the form of a hydrate, compatibility with the molybdenum-doped porous titanium metal substrate can be improved.

[0064] According to one embodiment of the present invention, the ruthenium precursor solution may have a ruthenium precursor content of 0.01 mol% or more and 0.02 mol% or less. Specifically, the ruthenium precursor content contained in the ruthenium precursor solution may be 0.011 mol% or more and 0.019 mol%, 0.012 mol% or more and 0.018 mol%, 0.013 mol% or more and 0.017 mol%, 0.014 mol% or more and 0.016 mol%, 0.015 mol% or more and 0.017 mol%, or 0.014 mol% or more and 0.017 mol% or less. When the ruthenium precursor content contained in the ruthenium precursor solution is within the above-mentioned range, ruthenium dioxide particles can be stably formed on the surface of the titanium metal substrate. In addition, by adjusting the content of the ruthenium precursor contained in the ruthenium precursor solution within the above-described range, the ruthenium content of the hydrogen generation electrode can be appropriately adjusted as described below, thereby further improving the stability and electrochemical properties of the electrode.

[0065] When the content of the ruthenium precursor is within the above-mentioned range, a hydrogen generation electrode including molybdenum-ruthenium-titanium composite oxide particles can be stably manufactured on a porous titanium metal substrate through the second hydrothermal reaction. In addition, by controlling the content of the ruthenium precursor within the above-mentioned range, as described below, a hydrogen generation electrode having excellent electrochemical properties while minimizing the content of the ruthenium particles can be manufactured.

[0066] The above second hydrothermal reaction can effectively reduce the overall cost required for manufacturing a hydrogen generation electrode comprising molybdenum-ruthenium-titanium composite oxide particles on a porous titanium metal substrate. In other words, a hydrogen generation electrode with excellent price competitiveness can be manufactured through a method according to an embodiment of the present invention.

[0067] According to one embodiment of the present invention, the second hydrothermal reaction may be performed at a temperature of 130°C or more and 180°C or less for a time of 8 hours or more and 15 hours or less. Specifically, the temperature at which the second hydrothermal reaction is performed may be 140°C or more and 170°C or less, 150°C or more and 160°C or less, 130°C or more and 160°C or less, 140°C or more and 150°C or less, 140°C or more and 180°C or less, or 150°C or more and 170°C or less. In addition, the time at which the second hydrothermal reaction is performed may be 9 hours or more and 13 hours or less, 10 hours or more and 12 hours or less, 8 hours or more and 11 hours or less, 10 hours or more and 15 hours or less, or 10 hours or more and 13 hours or less. By controlling the temperature and time at which the second hydrothermal reaction is performed within the above-mentioned range, an electrode for hydrogen generation including molybdenum-ruthenium-titanium composite oxide particles on a porous titanium metal substrate can be formed more stably and efficiently.

[0068] According to one embodiment of the present invention, the second hydrothermal reaction can heat the ruthenium precursor solution at a temperature increase rate of 5°C / min to 15°C / min, 7°C / min to 13°C / min, 5°C / min to 10°C / min, or 10°C / min to 15°C / min within the above-described temperature range. When the temperature increase rate is within the above-described range, a rapid thermal shock is prevented from being applied to the reactant, which is the ruthenium precursor, thereby enabling more stable production of the hydrogen generation electrode.

[0069] According to one embodiment of the present invention, the temperature at which the first hydrothermal reaction is performed may be higher than the temperature at which the second hydrothermal reaction is performed, and the time at which the first hydrothermal reaction is performed may be shorter than the time at which the second hydrothermal reaction is performed. Through this, the efficiency of the entire manufacturing process of the hydrogen generation electrode can be improved, and there is a process advantage in that the manufacturing cost and time can be effectively reduced.

[0070] Next, the molybdenum-doped titanium dioxide layer on which the above ruthenium dioxide particles are formed is heat-treated.

[0071] Through the above heat treatment, molybdenum-doped titanium dioxide on the porous substrate diffuses into ruthenium dioxide particles to form molybdenum-ruthenium-titanium composite oxide particles.

[0072] According to one embodiment of the present invention, the heat treatment can be performed at a temperature of 150°C or more and 250°C or less. Specifically, the heat treatment temperature may be 165°C or more and 235°C or less, 180°C or more and 220°C or less, 190°C or more and 210°C or less, 150°C or more and 220°C or less, 170°C or more and 210°C or less, 180°C or more and 200°C or less, 180°C or more and 250°C or less, 190°C or more and 230°C or less, or 200°C or more and 220°C or less. By controlling the heat treatment temperature within the above-mentioned range, the stability and electrochemical properties of the hydrogen generation electrode including the molybdenum-ruthenium-titanium composite oxide particles formed on the porous titanium metal substrate can be effectively improved. Specifically, when the heat treatment temperature is within the aforementioned range, composite particles having a titanium dioxide shell doped with molybdenum on the surface of a ruthenium dioxide core can be effectively formed. This improves electrochemical properties when used as a hydrogen generation electrode, and effectively suppresses the dissolution of the ruthenium particles.

[0073] According to one embodiment of the present invention, the heat treatment step may be performed for a period of 20 minutes to 2 hours. Specifically, the heat treatment step may be performed for a period of 20 minutes to 1 hour. By controlling the time for which the heat treatment step is performed within the above-described range, the molybdenum-ruthenium-titanium composite oxide particles having the core-shell structure can be effectively formed.

[0074] Specifically, the temperature and time of the above heat treatment step can exhibit the best performance when performed at 200°C for 40 minutes.

[0075]

[0076] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0077]

[0078] Example 1

[0079] A porous titanium metal substrate (MTIKOREA, EQ-TiF-1106, porosity: 40%) was prepared, MoCl5 (Aldrich, purity 99%) was prepared as a molybdenum precursor, RuCl3ㆍ3H2O (Aldrich, purity 99.98%) was prepared as a ruthenium precursor, and hydrogen peroxide (Aldrich, 50%) was prepared.

[0080] Porous titanium metal substrates (MTIKOREA, EQ-TiF-1106, porosity: 40%) were prepared as discs with a diameter of 1 cm and a thickness of 1 mm. After ultrasonic cleaning with acetone, ethanol, and distilled water for 5 minutes each, the substrates were washed again with ethanol, and finally washed with distilled water for 3 minutes and dried to prepare porous titanium metal substrates. Afterwards, the porous titanium metal substrates were immersed in 50 wt% hydrogen peroxide heated to 70°C for 30 minutes to prepare porous titanium metal substrates with a titanium dioxide layer formed on the surface.

[0081] A molybdenum precursor solution having a MoCl5 content of 0.001 mol% was prepared and coated on the titanium metal substrate having the titanium dioxide layer formed thereon. Thereafter, the solution was transferred to a Teflon container and placed in an autocave to perform a hydrothermal reaction in a hydrothermal synthesis furnace (CBF-S010M, Thermotech Co., Ltd.). At this time, the first hydrothermal reaction was performed at a heating rate of 10°C / min and at a temperature of 180°C for 12 hours. Thereafter, the metal substrate on which the hydrothermal reaction was completed was cooled to room temperature and washed with distilled water. The washed metal substrate was dried in a vacuum oven maintained at 70°C for 24 hours, thereby obtaining a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon.

[0082] The porous titanium metal substrate having the molybdenum-doped titanium dioxide layer formed thereon was coated using a ruthenium precursor solution having a RuCl3 content of 0.016 mol%. Thereafter, the porous titanium metal substrate having the molybdenum-doped titanium dioxide layer formed thereon and coated with the ruthenium precursor solution was transferred to a Teflon container and placed in an autoclave to undergo a hydrothermal reaction in a hydrothermal synthesis furnace. At this time, the hydrothermal reaction was performed at a heating rate of 10°C / min, and the hydrothermal reaction was performed at a temperature of 150°C for 10 hours. Thereafter, the metal substrate on which the hydrothermal reaction was completed was washed with distilled water. The washed metal substrate was dried in a vacuum oven maintained at 70°C for 24 hours.

[0083] Next, the molybdenum-doped titanium dioxide layer on which the ruthenium dioxide particles were formed was heat-treated. The heat treatment process was performed using a furnace, and was carried out at 200°C for 20, 40, and 60 minutes. Thus, a hydrogen generation electrode including molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate was manufactured.

[0084] Example 2

[0085] An electrode for hydrogen generation including molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate was manufactured in the same manner as in Example 1, except that the heat treatment process was performed for 40 minutes.

[0086] Example 3

[0087] An electrode for hydrogen generation including molybdenum-ruthenium-titanium composite oxide particles formed on a porous titanium metal substrate was manufactured in the same manner as in Example 1, except that the heat treatment process was performed for 60 minutes.

[0088]

[0089] Comparative Example 1

[0090] An electrode for hydrogen generation was manufactured in the same manner as in Example 1, except that the above heat treatment process was not performed.

[0091] Atomic analysis of the composite oxide particles among the electrodes manufactured in the above examples and comparative examples was performed through EDS mapping (elemental mapping) using TEM measurement, and the atomic ratios shown in Table 1 below were obtained.

[0092] Atomic ratio (%)TiRuMoExample 112.384.33.4Example 238.154.57.4Example 345.944.39.8Comparative example 14.194.61.3

[0093] As shown in Table 1 above, in Examples 1 to 3, the Mo and Ti contents are higher than in Comparative Example 1, indicating that a shell made of titanium dioxide doped with molybdenum was formed, and that the thickness of the shell increases with the heat treatment time.

[0094] Reference example

[0095] Ru / C and RuO2 / C electrodes, which are most commonly used in general alkaline electrolyte hydrogen evolution reactions, were manufactured.

[0096]

[0097] Experimental example

[0098] Using the following experimental equipment, the properties of the manufactured hydrogen generation electrode were observed and evaluated.

[0099] 1. TEM: JEM-2100F, JEOL LTd. / Acceleration voltage condition of 200 kV

[0100] 2. Cs-TEM: Cs-corrected monochromated TEM (Themis Z, Thermo Fisher) / 300 kV acceleration voltage condition

[0101] 3. XRD: New D8 ADVANCE, Bruker / using Cu Kα radiation (λ = 0.1542 nm)

[0102] 4. FESEM: Field-emission scanning electron microscopy (Model: SU70, Hitachi)

[0103] 5. ICP-MS: Inductively coupled plasma-mass spectrometry (Model: NwxION 350D, Perkin-Elmer)

[0104]

[0105] Electrochemical property analysis

[0106] FIG. 2a is LSV data measuring the hydrogen generation performance of each hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2b is Tafel plot data of the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2c is data measuring the electrochemical specific surface area of ​​the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2d is data measuring the charge transfer resistance and exchange current density of the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, FIG. 2e is a graph showing the mass activity (data obtained by dividing the current density by the mass of ruthenium) of the example 2 of the present invention and the comparative example, FIG. 2f is a graph comparing the performance of the example 2 of the present invention and the previously reported alkaline condition hydrogen generation electrodes, and FIG. 2g is a graph comparing the performance of the example 2 of the present invention and the previously reported alkaline condition hydrogen generation electrodes with time at 100 mA cm of the example and the comparative example. -2 This is the data of the change in overvoltage at the current density, and Fig. 2h shows the data of 100 mA cm of the examples and comparative examples. -2 ICP-MS data at current density, and Fig. 2i is 100 mA cm -2 This is a graph measuring the stability of Example 2 at current density.

[0107] Referring to Fig. 2a, LSV data measuring the hydrogen generation performance of each hydrogen generation electrode manufactured in the examples and comparative examples of the present invention were measured under 1.0 M KOH conditions. It can be confirmed that the performance varies depending on the heat treatment time, and it can be seen that the examples have a lower overvoltage than comparative example 1. In particular, example 2 has a lower overvoltage of -10 mA cm -2 It can be seen that it exhibits the best performance with a low overvoltage of 2 mV at a current density of .

[0108] Figure 2b shows Tafel plot data that can measure charge transfer efficiency at low current densities. This data serves as an indicator of the electrochemical reaction mechanism, and the mechanism is determined by the slope. Referring to Figure 2b, it can be seen that the slopes of the examples are significantly lower than those of Comparative Example 1. Example 2 has values ​​that follow the Volmer-Tafel mechanism. Referring to the graph of Figure 2b, it can be confirmed that Example 2 has the fastest charge transfer performance because it shows the lowest value.

[0109] Figure 2c is data measuring the electrochemical specific surface area of ​​the molybdenum-doped titanium dioxide layer of the hydrogen generation electrode manufactured in the examples and comparative examples of the present invention, which is data measuring the size of the area actually participating in the reaction. The scan rates of the cyclic voltammetry measurement were 20, 60, 100, 200, and 300 mV s. -1 As the electrode was raised, the difference between the anodic current and the cathodic current, which increases accordingly, was plotted, and the slope was measured to determine the electrochemical specific surface area. As shown in Fig. 2c, the electrode of the present invention has a similar electrochemical specific surface area, and it can be seen that the electrochemical specific surface area is maintained even after heat treatment.

[0110] FIG. 2d shows data obtained by measuring the charge transfer resistance and exchange current density of the hydrogen generation electrodes manufactured in the Examples and Comparative Examples of the present invention. Charge transfer resistance is a value used as an indicator of the reaction rate at low current density. In the case of the resistance value, it can be confirmed that the Examples have smaller values ​​than Comparative Example 1, and among them, Example 2 has the smallest value. This means that the catalyst has excellent catalytic performance at low current density, that is, the slope of the rising curve in the graph of FIG. 2a is steep. The exchange current density is also used as an indicator of the reaction rate at low current density, and this value indicates how prepared the catalyst is for the reaction. A larger value means that the catalyst participates in the reaction quickly when an external voltage is applied. In the case of the exchange current density, it can be confirmed that the Examples have larger values ​​than Comparative Example 1, and among them, Example 2 has the largest value. It can be seen that this also contributes to the steep rising curve in the graph of FIG. 2a.

[0111] Figure 2e is a graph showing the mass activity of Example 2 of the present invention and a comparative example. The amount of Ru contained in each electrode of Example 2 and the reference examples was measured, and the data is the current density divided by the Ru mass. A comparison was made with commercial electrodes, and it can be confirmed that Example 2 shows a mass activity that is 13 times higher than that of a Ru / C electrode and 47 times higher than that of a RuO2 / C electrode.

[0112] Figure 2f shows data comparing the performance of Example 2 and the reported alkaline condition hydrogen generation reaction electrodes, with the comparison based on the overvoltage at 10 mA, and it can be confirmed that Example 2 has the best performance.

[0113] Figure 2g shows data confirming changes in overvoltage over time when a current density of 100 mA is applied to the examples and comparative examples. It can be seen that the examples show less change in overvoltage over time than the comparative examples, and in particular, examples 2 and 3 show a stable appearance without increasing overvoltage.

[0114] Figure 2h shows the hydrogen generation electrode of the example and comparative example at 100 mA cm -2 This is ICP-MS data measuring the ruthenium concentration in the electrolyte over time while passing a current density of . If the graph increases over time, it means that ruthenium is dissolved. It can be seen that the graph increases less over time in the examples than in the comparative examples, and in particular, in the case of examples 2 and 3, ruthenium hardly melts, showing a stable appearance. This stability is because the shell was formed from the 40-minute heat treatment.

[0115] Figure 2i shows data measuring the stability of Example 2 at a current density of 100 mA, and it can be confirmed that it operates stably for approximately 300 hours.

[0116]

[0117] Morphological analysis

[0118] FIG. 3a is a HAADF-STEM image before the electrochemical reaction of the hydrogen generation electrode manufactured in Example 2 of the present invention. Referring to FIG. 3a, it can be confirmed that particles of about 1 to 2 nm in size are formed.

[0119] FIG. 3b is an image of the line-scan measurement results of a sample before an electrochemical reaction of an electrode for hydrogen generation manufactured in Example 2 of the present invention. Referring to FIG. 3b, it can be confirmed that the electrode has a molybdenum-doped titanium dioxide shell with a thickness of 0.45 nm, and it can be inferred that the core is formed of ruthenium dioxide oxide.

[0120] FIG. 3c is an XPS image of the hydrogen generation electrode manufactured in Example 2 of the present invention before and after the electrochemical reaction. Referring to FIG. 3c, it can be seen that only ruthenium 4 exists before the electrochemical reaction and ruthenium 0 increases after the reaction. This shows that only ruthenium dioxide oxide exists before the reaction and that the ruthenium dioxide oxide was reduced to a ruthenium metal substance after the electrochemical reaction. In addition, it can be seen that the amount of titanium dioxide forming the shell was reduced and reduced at the same time through the decrease in the titanium 4 peak and the shift to a lower energy position.

[0121] FIG. 3d is a TEM image of the hydrogen generation electrode manufactured in Example 2 of the present invention after an electrochemical reaction. Referring to FIG. 3d, the lattice constant of ruthenium metal is confirmed along with the lattice constant of titanium dioxide. That is, it can be confirmed that the lattice constants of the existing RuO2 have been changed to the lattice constant of Ru metal.

[0122] FIG. 3e is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image after the electrochemical reaction of the hydrogen generation electrode manufactured in Example 2 of the present invention. Referring to FIG. 3e, at the atomic level, there are atoms that shine very brightly and atoms that exist in a grayish turbidity. Through this, it can be inferred that the atoms that shine very brightly are ruthenium metal atoms whose shells have been removed and are exposed, and the atoms that are grayish turbidity are ruthenium metal atoms that exist under the shells with their shells remaining. As a result, it can be seen that a porous reduced titanium shell was formed.

[0123] FIG. 3f is an electron energy loss spectrum (EELS) image of a sample after an electrochemical reaction of the hydrogen generation electrode manufactured in Example 2 of the present invention. Referring to FIG. 3f, the signal of titanium can be confirmed by dividing the region from brightly glowing atoms to cloudy gray atoms. The brightly glowing part can be confirmed to be the part where the ruthenium atoms are exposed because the titanium signal is not confirmed, and the cloudy gray atoms can be confirmed to be the part where the shell remains because the titanium peak is confirmed.

[0124] Figure 3g is an image of a line scan measured by dividing the atoms of Example 2 into 5 regions after the electrochemical reaction. Referring to Figure 3g, it can be confirmed that a titanium shell with a thickness of 0.48 nm remains on the outside, and in the core, the ruthenium signal increases more than the titanium signal after the electrochemical reaction. The fact that the titanium signal on the inside is not flat but fluctuates is confirmed to be because the signal in the area where the shell does not exist decreases as the shell becomes porous. This confirms once again that a porous titanium shell has been formed.

[0125]

[0126] Performance Analysis

[0127] Figure 4 is a graph showing the performance in an anion exchange membrane electrolysis (AEMWE) process using a hydrogen generation electrode manufactured in an embodiment of the present invention.

[0128] Figure 4a is a schematic diagram of the reactor of AEMWE, and the performance of the hydrogen generation electrode manufactured in the example of the present invention was evaluated using a water electrolysis system called Anion-exchange-membrane water electrolysis (AEMWE).

[0129] Figure 4b is a graph comparing the performance of a water electrolysis system using the hydrogen generation electrode manufactured in Example 2 of the present invention and the commercial electrode iridium dioxide as an anode electrode (oxygen evolution reaction), and a water electrolysis system using the commercial electrodes platinum / carbon electrode and iridium dioxide electrode. At a cell voltage of 2.0 V, the hydrogen generation electrode manufactured in Example 2 of the present invention shows a current density of 3.35 A, and the hydrogen generation electrode manufactured in Comparative Example 2 shows a current density of 1.22 A. That is, it can be seen that the hydrogen generation electrode manufactured in Example 2 of the present invention shows very excellent performance compared to Comparative Example 2 (commercial electrode).

[0130] Figure 4c is a performance comparison table between the hydrogen generation electrode manufactured in Example 2 of the present invention and electrodes reported so far, and it can be confirmed that the hydrogen generation electrode manufactured in Example 2 of the present invention shows the best performance among the currently reported catalysts.

[0131] Figure 4d is data analyzing the contribution to electrode performance, and it can be confirmed that when the hydrogen generation electrode manufactured in Example 2 of the present invention was used, the portion contributing to the overvoltage at the reduction electrode was greatly reduced, resulting in an overall low overvoltage (high performance).

[0132] Figure 4e shows data measuring the stability of the hydrogen generation electrode manufactured in Example 2 at a current density of 500 mA, and showed a stable appearance for more than 500 hours. After 400 hours, the performance showed a gradual decrease, which was thought to be due to the melting of iridium dioxide used in the oxygen evolution reaction, which is a cathode reaction. Therefore, the hydrogen generation reaction performance was evaluated once again using the hydrogen generation electrode manufactured in Example 2 of the present invention, for which stability measurement was completed.

[0133] Figure 4f is a graph showing the hydrogen generation reaction performance evaluated again using the hydrogen generation electrode manufactured in Example 2 of the present invention, which completed the stability measurement of Figure 4e. Referring to this, it can be confirmed that it maintains similar performance to before the stability evaluation. In other words, it was confirmed that the hydrogen generation electrode manufactured in Example 2 of the present invention itself is very stable.

[0134]

[0135] The detailed description above is intended to illustrate and explain the present invention. Furthermore, the foregoing merely illustrates and describes preferred embodiments of the present invention. As described above, the present invention can be utilized in various other combinations, modifications, and environments, and variations or modifications can be made within the scope of the inventive concepts disclosed herein, the scope equivalent to the above-described disclosure, and / or the scope of technology or knowledge in the art. Therefore, the detailed description of the invention above is not intended to limit the present invention to the disclosed embodiments. Furthermore, the appended claims should be construed to include other embodiments.

[0136]

[0137] Description of the symbol

[0138] 1: Molybdenum-doped titanium dioxide layer on a porous titanium metal substrate

[0139] 2: Ruthenium dioxide core / 2`: Ruthenium core

[0140] 3: Molybdenum-doped titanium dioxide shell / 3`: Porous titanium shell

[0141] 4: Molybdenum atom

Claims

1. Porous titanium metal substrate; A titanium dioxide layer formed on the porous titanium metal substrate, having a nano-sized surface roughness and doped with molybdenum; and A hydrogen generation electrode comprising a plurality of molybdenum-ruthenium-titanium composite oxide particles positioned on a molybdenum-doped titanium dioxide layer, An electrode for hydrogen generation, wherein the above molybdenum-ruthenium-titanium composite oxide particles are composed of a ruthenium dioxide core and a molybdenum-doped titanium dioxide shell.

2. In paragraph 1, The above molybdenum-ruthenium-titanium composite oxide particle is a hydrogen generation electrode in which, during a hydrogen generation reaction, ruthenium (Ru) dioxide of the core is reduced to ruthenium (Ru) metal, the molybdenum-doped titanium dioxide of the shell is reduced to porous titanium, and the molybdenum atoms doped in the titanium dioxide are present at the interface between the ruthenium metal core and the porous reduced titanium shell.

3. In paragraph 1, The above shell is a single layer, An electrode for hydrogen generation, wherein the thickness of the above shell is 1Å or more and 8Å or less.

4. In paragraph 1, An electrode for hydrogen generation, wherein the average particle diameter of the above molybdenum-ruthenium-titanium composite oxide particles is 1.0 nm or more and 3.0 nm or less.

5. In paragraph 1, An electrode for hydrogen generation, wherein the thickness of the above molybdenum-doped titanium dioxide layer is 30 nm or more and 50 nm or less.

6. In paragraph 1, The above molybdenum-ruthenium-titanium composite oxide particles have a unit surface area of ​​1 cm on the porous titanium metal substrate. 2 An electrode for hydrogen generation containing 0.0001 g or more and 0.0003 g or less of ruthenium.

7. In paragraph 1, The above titanium metal substrate is a hydrogen generation electrode in the form of a foam.

8. A step of oxidizing a porous titanium metal substrate to form a titanium dioxide layer on the surface; A step of manufacturing a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed thereon by coating a molybdenum precursor solution on the porous titanium metal substrate having the titanium dioxide layer formed thereon and then performing a first hydrothermal reaction; A step of coating a ruthenium precursor solution on a porous titanium metal substrate having the molybdenum-doped titanium dioxide layer formed thereon and then performing a second hydrothermal reaction to form a plurality of ruthenium dioxide particles embedded in the molybdenum-doped titanium dioxide layer; and A step of heat treating a porous titanium metal substrate having a molybdenum-doped titanium dioxide layer formed with the above ruthenium dioxide particles embedded therein; A method for manufacturing an electrode for hydrogen generation according to any one of claims 1 to 7, comprising:

9. In paragraph 8, A method for manufacturing an electrode for hydrogen generation reaction, wherein the step of forming a titanium dioxide layer on the surface by oxidizing the porous titanium metal substrate is performed at a temperature of 50°C or higher and 90°C or lower for a time of 20 minutes or longer and 40 minutes or shorter.

10. In paragraph 8, A method for manufacturing an electrode for hydrogen generation reaction, wherein the content of the molybdenum precursor in the above molybdenum precursor solution is 0.005 mol% or more and 0.015 mol% or less.

11. In paragraph 8, A method for manufacturing an electrode for hydrogen generation reaction, wherein the first hydrothermal reaction is performed at a temperature of 150°C or more and 200°C or less for a time of 5 hours or more and 8 hours or less.

12. In paragraph 8, A method for manufacturing an electrode for hydrogen generation reaction, wherein the content of the ruthenium precursor in the above ruthenium precursor solution is 0.01 mol% or more and 0.02 mol% or less.

13. In paragraph 8, A method for manufacturing an electrode for hydrogen generation, wherein the second hydrothermal reaction is performed at a temperature of 130°C or higher and 180°C or lower for a time of 8 hours or higher and 15 hours or lower.

14. In paragraph 8, A method for manufacturing an electrode for hydrogen generation, wherein the above heat treatment is performed at a temperature of 150°C or higher and 250°C or lower.

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