Catalyst for water electrolysis electrode, method for manufacturing catalyst for water electrolysis electrode and water electrolysis electrode

Abstract

This disclosure relates to a catalyst for water electrolysis electrodes, a method for producing a catalyst for water electrolysis electrodes, and a water electrolysis electrode. [Solution] A catalyst for a water electrolysis electrode according to one embodiment comprises a carbon structure doped with a first element and a second element, and alloy nanoparticles doped with the first element, wherein the alloy nanoparticles are supported on the surface of the carbon structure, and the first element may be iron (Fe).

Description

[Technical Field]

[0001] This disclosure relates to a catalyst for water electrolysis electrodes, a method for producing a catalyst for water electrolysis electrodes, and a water electrolysis electrode. [Background technology]

[0002] Hydrogen energy is a clean energy source and is attracting attention as one of the promising alternative energy sources for solving energy problems in the long term. Among hydrogen production methods, water electrolysis, which uses electrical energy to separate water into hydrogen and oxygen, and thus does not emit carbon dioxide, is attracting much attention because it is environmentally friendly and can greatly contribute to achieving carbon neutrality.

[0003] On the other hand, water electrolysis reactions include the oxygen evolution reaction (OER) that occurs at the oxygen evolution electrode of a water electrolysis system and the hydrogen evolution reaction that occurs at the hydrogen evolution electrode. In acidic and alkaline media, the half-cell reaction and the total reaction can be represented as shown in chemical formulas 1 and 2 below.

[0004] [Chemical formula 1] Oxygen evolution reaction: 2H₂O(l) → O₂(g) + 4H + +4e - Hydrogen evolution reaction: 4H + +4e - →2H2(g) Total reaction: H2O(l) → H2(g) + 1 / 2O2(g)

[0005] [Chemical formula 2] Oxygen evolution reaction: 2OH - → 1 / 2O2(g) + H2O(l) + 2e - Hydrogen evolution reaction: 2H2O(l) + 2e - →H2(g)+2OH - Total reaction: H2O(l) → H2(g) + 1 / 2O2(g)

[0006] On the other hand, water electrolysis reactions using anion exchange membranes in alkaline media primarily utilize precious metal electrode catalysts such as platinum and iridium to lower reaction overpotential and improve hydrogen or oxygen generation performance and efficiency. However, the application of precious metal catalysts presents problems such as high costs and difficulty in adjusting supply and demand.

[0007] Therefore, there is a need for the development of catalysts for water electrolysis electrodes that can replace or reduce the precious metal content of precious metal catalysts while simultaneously possessing high hydrogen generation reaction performance. Specifically, there is a need for catalysts for hydrogen generation electrodes. [Overview of the project] [Problems that the invention aims to solve]

[0008] According to one aspect of this disclosure, it is possible to provide a catalyst for water electrolysis electrodes with excellent hydrogen evolution reaction performance, as well as a water electrolysis electrode containing the same, as a catalyst for water electrolysis electrodes with low transition metal loading amount and non-precious metal-based water electrolysis electrodes.

[0009] According to other aspects of this disclosure, it is possible to provide a method for producing a catalyst for a water electrolysis electrode that can efficiently produce a catalyst for a water electrolysis electrode. [Means for solving the problem]

[0010] The catalyst for a water electrolysis electrode according to this disclosure comprises a carbon structure doped with a first element and a second element, and alloy nanoparticles doped with the first element, wherein the alloy nanoparticles are supported on the surface of the carbon structure, and the first element may be iron (Fe).

[0011] In the catalyst for a water electrolysis electrode according to an embodiment, the carbon structure can include at least any one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite.

[0012] In the catalyst for a water electrolysis electrode according to an embodiment, the second element can be nitrogen.

[0013] In the catalyst for a water electrolysis electrode according to an embodiment, the alloy nanoparticles can be nickel-cobalt (Ni-Co) alloy nanoparticles.

[0014] In the catalyst for a water electrolysis electrode according to an embodiment, the nickel-cobalt alloy nanoparticles can contain an excess of nickel compared to cobalt.

[0015] In the catalyst for a water electrolysis electrode according to an embodiment, the catalyst for a water electrolysis electrode can be an Fe-N-C catalyst supporting iron (Fe)-doped nickel-cobalt alloy nanoparticles.

[0016] In the catalyst for a water electrolysis electrode according to an embodiment, the first element can be contained at 0.01 wt% to 0.10 wt% based on the total weight of the catalyst for a water electrolysis electrode.

[0017] The method for manufacturing a catalyst for a water electrolysis electrode according to the present disclosure includes a step of bringing a carbon precursor into contact with a first element precursor solution to form a carbon composite doped with the first element, and a step of impregnating the carbon composite doped with the first element into a metal precursor solution. The first element is iron (Fe), and the metal precursor solution can contain two or more different transition metal precursors.

[0018] In the method for producing a catalyst for a water electrolysis electrode according to one embodiment, the carbon precursor may include at least one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite.

[0019] In the method for producing a catalyst for a water electrolysis electrode according to one embodiment, the first element precursor solution may contain at least one or a mixture thereof selected from the group consisting of iron chloride, iron nitrate, iron acetate, iron sulfate, iron trifluoromethanesulfonate, iron citrate, iron acetylacetonate, and iron pyrophosphate.

[0020] In a method for producing a catalyst for a water electrolysis electrode according to one embodiment, the step of forming a carbon composite doped with the first element can be performed by treating the carbon precursor with nitrogen and then contacting it with the solution of the first element precursor.

[0021] In the method for producing a catalyst for water electrolysis electrodes according to one embodiment, the metal precursor solution may contain a nickel (Ni) precursor and a cobalt (Co) precursor.

[0022] In one embodiment, the method for producing a catalyst for a water electrolysis electrode may further include the step of heat-treating the metal precursor solution impregnated with the carbon composite doped with the first element in an inert atmosphere.

[0023] In the method for manufacturing a catalyst for a water electrolysis electrode according to an embodiment, in the heat treatment step, heat treatment can be performed at a temperature of 600°C to 1000°C for 30 minutes to 2 hours.

[0024] The water electrolysis electrode according to the present disclosure includes a base material and a catalyst for a water electrolysis electrode loaded on the base material. The catalyst for a water electrolysis electrode includes a carbon structure doped with a first element and a second element and alloy nanoparticles doped with the first element. The alloy nanoparticles are supported on the surface of the carbon structure, and the first element can be iron (Fe).

[0025] In the water electrolysis electrode according to an embodiment, the alloy nanoparticles can be nickel-cobalt (Ni-Co) alloy nanoparticles.

[0026] In the water electrolysis electrode according to an embodiment, the catalyst for a water electrolysis electrode can be an Fe-N-C-based catalyst on which nickel-cobalt alloy nanoparticles doped with iron (Fe) are supported.

[0027] In the water electrolysis electrode according to an embodiment, the first element can be contained at 0.01 wt% to 0.10 wt% based on the total weight of the catalyst for a water electrolysis electrode.

[0028] In the water electrolysis electrode according to an embodiment, the loading amount of the catalyst for a water electrolysis electrode is 0.1 mg / cm 2 ~5.0 mg / cm 2 and can be such.

[0029] In the water electrolysis electrode according to an embodiment, the Tafel slope can be 200 mV / dec or less.

Advantages of the Invention

[0030] According to one aspect of the present disclosure, as a catalyst for a non-noble metal-based water electrolysis electrode with a low loading amount of a transition metal, a catalyst for a water electrolysis electrode having excellent hydrogen generation reaction performance and a water electrolysis electrode including the same can be provided.

[0031] According to other aspects of this disclosure, it is possible to provide a method for producing a catalyst for a water electrolysis electrode that can efficiently produce a catalyst for a water electrolysis electrode. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows an example of the surface structure of a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure. [Figure 2] This is a block diagram showing an example of a method for producing a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure. [Figure 3] This image shows a TEM image and EDS mapping result of the catalyst for the water electrolysis electrode in the example. [Figure 4] This graph shows the XRD pattern of the catalyst for the water electrolysis electrode in the example. [Figure 5] This figure shows an example of a three-electrode system configured for evaluating electrochemical properties. [Figure 6] This graph shows the current density vs. voltage curves evaluating the hydrogen generation reaction performance of the water electrolysis electrodes in Example, Comparative Example 1, Comparative Example 3, and Comparative Example 4. [Figure 7] This graph shows the hydrogen generation reaction performance of the water electrolysis electrodes in Example, Comparative Example 1, Comparative Example 3, and Comparative Example 4, as evaluated by overpotential vs. log current density curves. [Figure 8] This figure shows an example of the surface structure of a catalyst for a water electrolysis electrode in Comparative Example 3. [Modes for carrying out the invention]

[0033] Since the embodiments described herein can be modified into various other forms, the technology of one embodiment is not limited to the embodiments described below. Furthermore, throughout the specification, unless otherwise specified, "includes," "equips," "contains," or "has" a component, it means that other components may be further included, rather than excluding other components, and does not exclude any elements, materials, or processes not listed additionally.

[0034] In this specification, "same" or "uniform" can mean the same or uniform with respect to each other within an acceptable margin of error, unless otherwise explicitly stated. For example, "same" in terms of a certain composition or physical property measurement can mean that the two objects being compared are not exactly the same, but also the same within a margin of error. On the other hand, "same" in terms of a certain physical property measurement can mean that the difference in measurements between the objects is less than approximately 5%, specifically less than 3%, and more specifically less than 1%.

[0035] The numerical ranges used herein include lower and upper limits and all values ​​within those limits, increments logically derived from the form and width of the defined range, all double-limited values, and all possible combinations of upper and lower limits of numerical ranges limited in different forms.

[0036] In this specification, unless otherwise defined, “approximately” can be considered to be a value within 30%, 25%, 20%, 15%, 10%, or 5% of the explicitly stated value.

[0037] In this specification, the use of terms such as "first," "second," and "third" preceding a component is intended to avoid confusion of the component being referred to, and is unrelated to the order, importance, or hierarchical relationship between the components. For example, an invention including only the second component without the first component is also embodied.

[0038] In this specification, "contact" or "to come into contact" can mean direct physical and chemical contact between one object and another object, and can also mean, without limitation, contact between one object and yet another object via another object. On the other hand, it is preferable, but not limited to, that physical and chemical interactions between objects may be induced by contact between one object and another object.

[0039] As used herein, the term "salt" can mean, without limitation, the ionic form of a compound or chemical structure that includes a cation or anion compound in order to form an electrically neutral compound or structure.

[0040] As used herein, the term "water electrolysis" can mean, without limitation, any reaction or series of processes that use electrical energy to decompose water (H2O) into gaseous hydrogen (H2) and oxygen (O2).

[0041] The following describes the disclosure in detail. However, this is illustrative only, and the disclosure is not limited to the specific embodiments described illustratively.

[0042] Catalyst for water electrolysis electrodes

[0043] Figure 1 shows an example of the surface structure of a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure.

[0044] A catalyst 10 for a water electrolysis electrode according to one embodiment of the present disclosure comprises a carbon structure 300 doped with a first element 100 and a second element 200, and alloy nanoparticles 400 doped with the first element 100, wherein the alloy nanoparticles 400 are supported on the surface of the carbon structure 300, and the first element 100 may be iron (Fe).

[0045] In one embodiment, the catalyst 10 for the water electrolysis electrode may include a carbon structure 300 doped with a first element 100 and a second element 200, and alloy nanoparticles 400 doped with the first element 100.

[0046] In one embodiment, the alloy nanoparticles 400 can be supported on the surface of the carbon structure 300.

[0047] In one embodiment, the carbon structure 300 may be a carbon structure doped with the first element 100 and the second element 200.

[0048] In one embodiment, the carbon structure 300 may be a nanoscale or microscale structure. On the other hand, in an exemplary embodiment, the carbon structure may be either a one-dimensional structure or a two-dimensional structure. Exemplarily, the carbon structure 300 can be defined as a structure of various shapes such as a sphere, fiber, disc, wire, web, pillar, rod, ribbon, plate, wall, or tube.

[0049] In exemplary embodiments, the carbon structure 300 can be formed in a size within the range of 0.1 nm to 1000 μm, more specifically 0.1 nm to 100 μm, more specifically 0.1 nm to 1000 nm, or 0.1 nm to 500 nm, although this is not necessarily limited to the above.

[0050] In one embodiment, the carbon structure 300 may include at least one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite. While not necessarily limited thereto, the carbon structure 300 may specifically include carbon black.

[0051] In one embodiment, the carbon black can be a concept that includes at least one of acetylene black, ketjen black, and super P.

[0052] In one embodiment, the term graphite may be a concept that does not limit itself to natural graphite, artificial graphite, or mixtures thereof.

[0053] In one embodiment, as will be described later, the carbon structure 300 may exist as a composite produced by physically and chemically treating a precursor. The precursor may be a carbon precursor. The carbon precursor may include, but is not limited to, at least one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite, but the carbon precursor may specifically include carbon black.

[0054] The composite carbon structure 300 may, for example, have a heterogeneous element doping structure in which one or more of the carbon atoms constituting the structure are substituted with a different element, or in which a different element is inserted. In a specific example, the carbon structure 300 may be a composite carbon structure doped with a first element 100 and a second element 200.

[0055] Figure 1 shows an example of the surface of the carbon structure 300 described above. In Figure 1, the surface of the carbon structure 300 according to one embodiment is exemplified as a honeycomb structure in which each element is located at each vertex. As shown in Figure 1, carbon atoms are mainly located at each vertex of the structure.

[0056] Referring to Figure 1, some carbon atoms are substituted or inserted with element 100 or element 200. Such substitution or insertion can deform a portion of the existing honeycomb structure in the region where the substitution or insertion occurs and in at least a portion of the adjacent region. Alternatively, such substitution or insertion can also preserve the existing honeycomb structure in at least a portion of the region where the substitution or insertion occurs and in the adjacent region.

[0057] As mentioned above, in one embodiment, the first element 100 may be iron (Fe). The first element 100 can be doped into both the carbon structure 300 and the alloy nanoparticles 400.

[0058] In exemplary embodiments, the first element 100 can be included in trace amounts in each of the carbon structure 300 and / or the alloy nanoparticles 400 by doping them, respectively.

[0059] In one embodiment, the second element 200 may be nitrogen.

[0060] In a nitrogen-doped carbon structure, the nitrogen-doped region can provide an active site. On the other hand, the first element 100, specifically iron (Fe), is a monatomic atom and can exist in a form coordinated with the doped nitrogen atom.

[0061] In such embodiments, the first element 100 may be included in a form that is coordinately bonded to the second element 200.

[0062] In the exemplary embodiment, the carbon structure may be a carbon structure with an Fe-NC structure.

[0063] Referring again to Figure 1, in one embodiment, the alloy nanoparticles 400 can be supported on the surface of the carbon structure 300.

[0064] In one embodiment, the alloy nanoparticles 400 can be doped with the first element 100.

[0065] In one embodiment, the alloy nanoparticles 400 can mean nanoscale particles without limitation. Exemplaryly, it can mean at least one region having nanoscale dimensions, or an example of a structure having characteristic dimensions. The alloy nanoparticles 400 may be monocrystalline, polycrystalline, amorphous, or a combination thereof.

[0066] In the exemplary embodiment, the alloy nanoparticles 400 are not necessarily limited to these, but may have an average particle size of 0.1 nm to 100 nm. More specifically, the average particle size of the alloy nanoparticles may be 0.5 nm or more, 1 nm or more, 2 nm or more, 5 nm or more, 7 nm or more, 10 nm or more, 12 nm or more, 15 nm or more, or 20 nm or more, or 90 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, or 30 nm or less.

[0067] In one embodiment, the alloy nanoparticles may be alloy nanoparticles made of an alloy of different metal elements.

[0068] In one embodiment, the alloy nanoparticles 400 may be alloy nanoparticles made of an alloy of at least two transition metal elements.

[0069] In one embodiment, the alloy nanoparticles 400 may be alloy nanoparticles made of an alloy of at least two or more periodic transition metal elements.

[0070] In one embodiment, the alloy nanoparticles 400 may be nickel-cobalt (Ni-Co) alloy nanoparticles.

[0071] In one embodiment, the nickel-cobalt alloy nanoparticles may contain an excess of cobalt relative to nickel.

[0072] In one embodiment, the nickel-cobalt alloy nanoparticles may contain five or more times more cobalt than nickel by weight. In specific embodiments, the nanoparticles may contain six or more, six.5 or more, seven or more, seven.5 or more, or eight or more times more cobalt than nickel by weight.

[0073] Referring again to Figure 1, in one embodiment, the alloy nanoparticles 400 may be alloy nanoparticles doped with the first element 100.

[0074] In a specific example, the first element 100 may be iron.

[0075] Therefore, in one embodiment, the alloy nanoparticles 400 may be iron-doped alloy nanoparticles.

[0076] In one embodiment, the iron-doped nickel-cobalt alloy nanoparticles may be alloy nanoparticles doped with a small amount of iron.

[0077] In one embodiment, the catalyst 10 for the water electrolysis electrode may be an Fe-NC system catalyst on which iron (Fe)-doped nickel-cobalt alloy nanoparticles are supported.

[0078] In one embodiment, the alloy nanoparticles 400 can induce reaction specificities different from existing ones through interactions between their constituent elements. In a specific embodiment, the alloy nanoparticles 400 can induce reaction specificities for hydrogen evolution reactions different from existing ones through interactions between iron, nickel, and cobalt.

[0079] In one embodiment, the alloy nanoparticles 400 can be uniformly supported on the surface of the carbon structure 300.

[0080] On the other hand, as described above, in the carbon structure 300, a transition metal element, specifically iron (the first element 100), can be coordinately bonded to a region doped with nitrogen (the second element 200), and this region can provide an active site. Alloy nanoparticles substantially containing an excess of nickel-cobalt, located near this site, can interact with the first element 100, specifically iron, doped at or near this site. Such interactions can further improve the hydrogen evolution reaction performance.

[0081] In one embodiment, the first element 100 may be included in an amount of 0.01% to 0.10% by weight based on the total weight of the water electrolysis electrode catalyst 10. Alternatively, in a specific embodiment, the content of the first element 100 can be 0.02% or more by weight, 0.03% or more by weight, 0.04% or more by weight, or 0.05% or more by weight, or 0.09% or less by weight, 0.08% or less by weight, 0.07% or less by weight, or 0.06% or less by weight. That is, in the water electrolysis electrode catalyst 10, the first element 100 may be included in an amount of 0.01% to 0.10% by weight, and in a specific embodiment, it can be included in an amount of 0.02% or more by weight, 0.03% or more by weight, 0.04% or more by weight, or 0.05% or more by weight, or 0.09% or less by weight, 0.08% or less by weight, or 0.07% or less by weight.

[0082] In one embodiment, the first element 100 may be present in an amount of 0.10% to 0.50% by weight based on the total weight of the alloy nanoparticles 400. Alternatively, in a specific embodiment, the content of the first element 100 can be 0.20% or more by weight, 0.25% or more by weight, 0.30% or more by weight, or 0.45% or less by weight, or 0.40% or less by weight. That is, in the alloy nanoparticles 400, the first element 100 may be present in an amount of 0.10% to 0.50% by weight, and in a specific embodiment, it may be present in an amount of 0.20% or more by weight, 0.25% or more by weight, or 0.30% or more by weight, or 0.45% or less by weight, or 0.40% or less by weight.

[0083] In one embodiment, the second element 200 may be present in an amount of 0.1% to 1.0% by weight based on the total weight of the water electrolysis electrode catalyst 10. Alternatively, in a specific embodiment, the content of the second element 200 can be 0.2% or more by weight, 0.3% or more by weight, 0.4% or more by weight, or 0.5% or more by weight, or 0.9% or less by weight, 0.8% or less by weight, or 0.7% or less by weight. That is, in the water electrolysis electrode catalyst 10, the second element 200 may be present in an amount of 0.1% to 1.0% by weight, and in a specific embodiment, it can be present in an amount of 0.2% or more by weight, 0.3% or more by weight, 0.4% or more by weight, or 0.5% or more by weight, or 0.9% or less by weight, 0.8% or less by weight, or 0.7% or less by weight.

[0084] In one embodiment, as described above, if the alloy nanoparticles are nickel-cobalt alloy nanoparticles, the catalyst 10 for the water electrolysis electrode may contain nickel in an amount of 0.1% to 2.0% by weight. In specific embodiments, it may contain 0.3% or more by weight, 0.5% or more by weight, 0.7% or more by weight, 0.8% or more by weight, or 0.9% or more by weight, or 1.9% or less by weight, 1.8% or less by weight, 1.6% or less by weight, 1.4% or less by weight, 1.2% or less by weight, or 1.1% or less by weight.

[0085] In one embodiment, as described above, if the alloy nanoparticles are nickel-cobalt alloy nanoparticles, the catalyst 10 for the water electrolysis electrode may contain cobalt in an amount of 1% to 12% by weight. In specific embodiments, it may contain 3% or more by weight, 5% or more by weight, 6% or more by weight, or 7% or more by weight, or 11% or less by weight, 10% or less by weight, 9.5% or less by weight, or 9% or less by weight.

[0086] Method for producing catalyst for water electrolysis electrode

[0087] Figure 2 is a block diagram showing an example of a method for producing a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure.

[0088] A method for producing a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure includes the steps of: S10, contacting a carbon precursor with a first element precursor solution to form a carbon composite doped with the first element; and S20, impregnating the carbon composite doped with the first element with a metal precursor solution, wherein the first element is iron (Fe), and the metal precursor solution may contain two or more different transition metal precursors.

[0089] In one embodiment, in step S10, the carbon precursor can be brought into contact with the first element precursor solution to form a carbon composite doped with the first element.

[0090] As described above, in one embodiment, the carbon precursor may include at least one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite. However, it is not necessarily limited thereto, but the carbon precursor may specifically include carbon black.

[0091] In one embodiment, the carbon black can be a concept that includes at least one of acetylene black, ketjen black, and super P.

[0092] In one embodiment, the term graphite may be a concept that does not limit itself to natural graphite, artificial graphite, or mixtures thereof.

[0093] In one embodiment, the carbon precursor may be a carbon precursor prepared by acid treatment. In a specific example, the carbon precursor can be prepared by contacting it with an acidic solution and then drying it.

[0094] In one embodiment, the acidic solution can be a strong acid such as nitric acid, sulfuric acid, or hydrochloric acid, or a mixture thereof. On the other hand, the carbon precursor can be exposed to such an acidic solution for 12 to 36 hours. Specifically, the carbon precursor can be exposed to such an acidic solution by immersing it in the solution or by spraying the solution onto the carbon precursor.

[0095] In one embodiment, the carbon precursor described above can be brought into contact with a solution of the first element precursor.

[0096] In one embodiment, the first element precursor solution may contain a transition metal precursor. In a specific embodiment, the first element precursor solution may contain an iron precursor.

[0097] In one embodiment, the transition metal precursor may include a transition metal salt. In a specific embodiment, the iron precursor may include an iron salt.

[0098] In one embodiment, the first element precursor solution may include at least one or a mixture thereof selected from the group consisting of iron chloride, iron nitrate, iron acetate, iron sulfate, iron trifluoromethanesulfonate, iron citrate, iron acetylacetonate, and iron pyrophosphate. However, the first element precursor solution may specifically be an aqueous solution of iron chloride.

[0099] The above-mentioned first element precursor solution can function as an oxidizing agent. By contacting the above-mentioned first element precursor solution with the above-mentioned carbon precursor, the above-mentioned first element can be doped into the carbon precursor. Specifically, iron can be doped into the carbon precursor through the process described above.

[0100] In one embodiment, the carbon precursor can be doped with the first element by bringing the carbon precursor into contact with the first element precursor solution and stirring. While not necessarily limited thereto, the stirring may, for example, be carried out for 1 hour or more, 2 hours or more, 3 hours or more, or 6 hours or less. On the other hand, while not necessarily limited thereto, the contact may, for example, be carried out at a temperature of 10°C to 50°C.

[0101] In one embodiment, step S10, in which the carbon composite doped with the first element is formed, may involve treating the carbon precursor with nitrogen before contacting it with the solution of the first element precursor.

[0102] In one embodiment, step S10 may include step S11 of treating the carbon precursor with nitrogen.

[0103] In one embodiment, the nitrogen treatment can be carried out using a nitrogen source that contains nitrogen atoms in its molecule, such as a nitrogen-containing compound, a nitrogen and carbon-containing compound, or other nitrogen-containing organic matter. In non-limiting embodiments, the nitrogen source may be provided in a liquid phase medium or in a fluid flow.

[0104] In exemplary embodiments, the nitrogen source may include pyrrole, polypyrrole, polyvinylpyrrole, methylpolypyrrole, pyrazole, pyridine, vinylpyridine, polyvinylpyridine, pyrimidine, piperazine, imidazole, methylimidazole, aniline, polyaniline, polyimide, polyamide, polyamideimide, acrylonitrile, polyacrylonitrile, ammonia, urea, adenine, melamine, and the like. In exemplary embodiments, the nitrogen source may include pyrrole and / or polypyrrole.

[0105] In exemplary embodiments, the nitrogen treatment may be carried out by dispersing the carbon precursor in a dispersion medium and then adding the nitrogen source as described above. In the above embodiments, after dispersing the carbon precursor in a dispersion medium, the nitrogen source is added and stirred to bring the carbon precursor into contact with the nitrogen source and obtain a nitrogen-treated carbon precursor.

[0106] The dispersion medium may also be a mixture of water and C1-C6 aliphatic alcohols, although this is not necessarily limited to the above. Specifically, the dispersion medium may be a mixture of water and propanol. On the other hand, the mixing ratio of the water and aliphatic alcohol mixture may be 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, or 8:2 by volume, but this is not necessarily limited to the above.

[0107] While not necessarily limited to these, for example, the stirring may be carried out for 10 minutes or more, 20 minutes or more, or for 1 hour or less, 50 minutes or less, or 40 minutes or less. On the other hand, while not necessarily limited to these, for example, the contact may be carried out at a temperature of 10°C to 50°C.

[0108] By step S11 as described above, a nitrogen-treated carbon precursor can be obtained. In a specific example, the nitrogen-treated carbon precursor may be a polypyrrole-carbon composite. The polypyrrole-carbon composite obtained by the above example can be effectively and uniformly doped with nitrogen atoms throughout its entire surface.

[0109] In the above embodiment, step S10 may further include step S12, in which a nitrogen-treated carbon precursor is brought into contact with a first element precursor solution. That is, in the above embodiment, step S10 may include steps S11 and S12. In a specific embodiment, step S12 may be performed after step S11.

[0110] In one embodiment, step S12 involves contacting the nitrogen-treated carbon precursor obtained in step S11, for example, a polypyrrole-carbon composite, with a first-element precursor solution, thereby forming a carbon composite doped with the first and second elements, for example, an iron-doped polypyrrole-carbon composite. The description of the carbon composite doped with the first and second elements as described above can be the same as the description of the carbon structure described above, and the description of contacting the nitrogen-treated carbon precursor with the first-element precursor solution in step S12 can be the same as the description above regarding step S10, except that a nitrogen-treated carbon precursor is used instead of the carbon precursor; therefore, redundant descriptions will be omitted below.

[0111] As described above, a carbon composite doped with the first and second elements can be formed in step S10.

[0112] In one embodiment, step S20 can be used to impregnate the carbon composite doped with the first element into the metal precursor solution. In a specific embodiment, step S20 can be used to impregnate the carbon composite doped with the first and second elements into the metal precursor solution.

[0113] In one embodiment, the metal precursor solution may contain two or more different transition metal precursors.

[0114] In one embodiment, the metal precursor solution may contain two or more different 4-period transition metal precursors.

[0115] In one embodiment, the metal precursor solution may contain a nickel (Ni) precursor and a cobalt (Co) precursor. In a specific embodiment, the metal precursor solution may contain a nickel precursor and a cobalt precursor.

[0116] In one embodiment, the nickel precursor may include a nickel salt. Non-limiting examples of nickel precursors containing the nickel salt include nickel nitrate, nickel sulfate, nickel fluoride, nickel chloride, nickel bromide, nickel acetate, nickel acetylacetonate, nickel citrate, and nickel phosphate.

[0117] In one embodiment, the cobalt precursor may include a cobalt salt. Non-limiting examples of cobalt precursors containing the cobalt salt include cobalt nitrate, cobalt sulfate, cobalt fluoride, cobalt chloride, cobalt bromide, cobalt acetate, cobalt acetylacetonate, cobalt citrate, and cobalt phosphate.

[0118] As an unrestricted example, the above metal precursor solution may contain nickel precursor and cobalt precursor in a ratio of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, or 1:9 by weight.

[0119] The solvent in the above metal precursor solution can be any aliphatic alcohol without restriction. Specifically, C1-C4 aliphatic alcohols can be used. In one example, the solvent can be propanol, but is not necessarily limited to this.

[0120] In non-restrictive examples, the impregnation may be carried out for 10 minutes or more, 30 minutes or more, 1 hour or more, 2 hours or more, or 3 hours or more, or for 48 hours or less, 36 hours or less, 24 hours or less, 20 hours or less, 18 hours or less, or 15 hours or less. On the other hand, in non-restrictive examples, the impregnation may be carried out while adding heat to the solution at 20°C or higher, 30°C or higher, 50°C or higher, 70°C or higher, 90°C or higher, 100°C or higher, 150°C or higher, or 200°C or higher.

[0121] In one embodiment, step S20 involves impregnating the carbon composite doped with the first element formed in step S10 into a metal precursor solution, specifically a metal precursor solution containing a nickel precursor and a cobalt precursor, as described above. This allows nickel and cobalt to be deposited onto the surface of the carbon composite in the form of alloy nanoparticles, resulting in a carbon structure supported on the surface of the carbon composite. On the other hand, in step S20, a portion of the first element doped into the carbon composite, specifically the iron element, can be partially migrated to the alloy nanoparticles supported on the carbon composite. As a result, steps S10 and S20 as described above can produce a catalyst for a water electrolysis electrode containing a carbon structure doped with the first and second elements, and alloy nanoparticles supported on the surface of the carbon structure and doped with the first element.

[0122] In one embodiment, the method may further include step S30, in which the metal precursor solution impregnated with the carbon composite doped with the first element is heat-treated in an inert atmosphere. That is, a method for producing a catalyst for a water electrolysis electrode according to one embodiment of the present disclosure may include step S30, in which the metal precursor solution impregnated with the carbon composite in step S20 is heat-treated in an inert atmosphere. Steps S20 and S30 may be carried out sequentially, or at least a portion of each step may be carried out in parallel.

[0123] In one embodiment, step S30 may be carried out under an inert atmosphere. For example, it can be carried out under an inert atmosphere formed by an inert gas such as nitrogen, helium, or argon. Although not necessarily limited to this, step S30 can be carried out under an inert atmosphere formed by nitrogen gas.

[0124] In one embodiment, the heat treatment step S30 can be performed at a temperature of 600°C to 1000°C for 30 minutes to 2 hours. That is, in step S30, the metal precursor solution impregnated with the carbon composite in step S20 can be heat-treated at a temperature of 600°C to 1000°C for 30 minutes to 2 hours under a nitrogen atmosphere.

[0125] In an unrestrictive embodiment, the heat treatment temperature in step S30 may be 650°C or higher, 700°C or higher, or 750°C or higher, or 950°C or lower, 900°C or lower, 880°C or lower, or 850°C or lower. On the other hand, in an unrestrictive embodiment, the time required for step S30 may be 40 minutes or higher, 50 minutes or higher, or 55 minutes or higher, or 110 minutes or lower, 100 minutes or lower, 90 minutes or lower, 80 minutes or lower, or 70 minutes or lower.

[0126] In one embodiment, step S30 can be performed by thermally decomposing the metal precursor solution impregnated with the carbon composite in step S20 under an inert atmosphere. This allows the alloy nanoparticles to be uniformly distributed on the surface of the carbon composite, further improving the hydrogen generation performance of the final catalyst.

[0127] water electrolysis electrode

[0128] A water electrolytic electrode according to one embodiment of the present disclosure comprises a substrate and a catalyst for a water electrolytic electrode loaded onto the substrate, wherein the catalyst for a water electrolytic electrode comprises a carbon structure doped with a first element and a second element, and alloy nanoparticles doped with the first element, the alloy nanoparticles being supported on the surface of the carbon structure, and the first element may be iron (Fe).

[0129] In one embodiment, the substrate may include at least one of titanium, nickel, chromium, aluminum, and stainless steel, or an alloy thereof. However, it may include, without limitation, any material that can maintain conductivity for use in water electrolysis electrodes in the industry.

[0130] In one embodiment, the base material can have various shapes such as rods, wires, plates, and meshes.

[0131] In one embodiment, the catalyst for the water electrolysis electrode comprises a carbon structure doped with a first element and a second element, and alloy nanoparticles supported on the surface of the carbon structure, wherein the base alloy nanoparticles can be doped with the first element.

[0132] In one embodiment, the catalyst for the water electrolysis electrode may be the catalyst for the water electrolysis electrode according to the embodiment of the present disclosure described above, or a catalyst for the water electrolysis electrode produced by the method for producing the catalyst for the water electrolysis electrode according to the embodiment of the present disclosure described above.

[0133] In one embodiment, the carbon structure may include at least one selected from the group consisting of carbon black, carbon nanotube, carbon nanofiber, carbon nanoribbon, fullerene, graphene, graphene nanoplatelet, and graphite. However, it is not necessarily limited to this, but the carbon structure 300 may specifically include carbon black.

[0134] In one embodiment, the second element may be nitrogen.

[0135] In one embodiment, the alloy nanoparticles may be nickel-cobalt (Ni-Co) alloy nanoparticles.

[0136] In one embodiment, the nickel-cobalt alloy nanoparticles may contain an excess of cobalt relative to nickel.

[0137] In one embodiment, the catalyst for the water electrolysis electrode may be an Fe-NC system catalyst on which iron (Fe)-doped nickel-cobalt alloy nanoparticles are supported.

[0138] In one embodiment, the first element may be present in an amount of 0.01% to 0.10% by weight based on the total weight of the catalyst for the water electrolysis electrode. Alternatively, in a specific embodiment, the content of the first element may be 0.02% or more by weight, 0.03% or more by weight, 0.04% or more by weight, or 0.05% or more by weight, or 0.09% or less by weight, 0.08% or less by weight, or 0.07% or less by weight. That is, in the catalyst for the water electrolysis electrode, the first element may be present in an amount of 0.01% to 0.10% by weight, and in a specific embodiment, it may be present in an amount of 0.02% or more by weight, 0.03% or more by weight, 0.04% or more by weight, or 0.05% or more by weight, or 0.09% or less by weight, 0.08% or less by weight, or 0.07% or less by weight.

[0139] In one embodiment, the first element 100 may be present in an amount of 0.10% to 0.50% by weight based on the total weight of the alloy nanoparticles 400. Alternatively, in a specific embodiment, the content of the first element 100 may be 0.20% or more by weight, 0.25% or more by weight, or 0.30% or more by weight, or 0.45% or less by weight, or 0.40% or less by weight. That is, in the alloy nanoparticles 400, the first element 100 may be present in an amount of 0.10% to 0.50% by weight, and in a specific embodiment, it may be present in an amount of 0.20% or more by weight, 0.25% or more by weight, or 0.30% or more by weight, or 0.45% or less by weight, or 0.40% or less by weight.

[0140] In one embodiment, the second element may be present in an amount of 0.1% to 1.0% by weight based on the total weight of the catalyst for the water electrolysis electrode. Alternatively, in a specific embodiment, the content of the second element may be 0.2% or more by weight, 0.3% or more by weight, 0.4% or more by weight, or 0.5% or more by weight, or 0.9% or less by weight, 0.8% or less by weight, or 0.7% or less by weight. That is, in the catalyst for the water electrolysis electrode, the second element may be present in an amount of 0.1% to 1.0% by weight, and in a specific embodiment, it may be present in an amount of 0.2% or more by weight, 0.3% or more by weight, 0.4% or more by weight, or 0.5% or more by weight, or 0.9% or less by weight, 0.8% or less by weight, or 0.7% or less by weight.

[0141] Furthermore, the above-described explanation regarding catalysts for water electrolysis electrodes can be applied without limitation by referring to Figures 1 and 2.

[0142] In one embodiment, the catalyst for the water electrolysis electrode is loaded onto the substrate to constitute a water electrolysis electrode according to one embodiment of the present disclosure.

[0143] In one embodiment, the loading method is not particularly limited as long as it falls under a method known in the industry. Exemplary methods include various methods such as depositing, spraying, or coating the catalyst onto the substrate.

[0144] In one embodiment, the loading amount of the catalyst for the water electrolysis electrode was 0.1 mg / cm³. 2 ~5.0 mg / cm³ 2 This may also be the case. That is, in one embodiment, the water electrolysis electrode has a catalyst for the water electrolysis electrode of 0.1 mg / cm³. 2 ~5.0 mg / cm³ 2 It can be loaded with a loading amount of 0.2 mg / cm³. In a specific example, the above loading amount is 0.2 mg / cm³. 2 More than 0.3mg / cm 2 More than 0.5mg / cm 2 More than 0.7mg / cm 2 The above is 0.9 mg / cm³. 2 More than 1.0mg / cm 2More than 1.2mg / cm 2 Above, or 1.6 mg / cm³ 2 It may be greater than or equal to 4.8 mg / cm³ 2 Below, 4.5mg / cm 2 Below, 4.3mg / cm 2 Below 4.0mg / cm 2 Below 3.5mg / cm 2 Below 3.0mg / cm 2 Below, 2.7mg / cm 2 The following, or 2.2 mg / cm³ 2 The following is also acceptable.

[0145] In one embodiment, the water electrolysis electrode may have a Tafel gradient of 200 mV / dec or less.

[0146] In one embodiment, the Tafel slope can refer to the slope of the Tafel plot curve shown based on the hydrogen evolution reaction polarization results measured in a 1M KOH solution at a scan rate of 5mV / s.

[0147] The above Tafel gradient can mean the value represented by B in the relationship defined by the following equation.

[0148] [Relationship] η = Blog(j / j0)

[0149] In the above relationship, η is the overvoltage, j is the current density, and j0 is the exchange current density.

[0150] The smaller the Tafel gradient shown above, the more favorable the reaction is kinetically for hydrogen evolution.

[0151] In specific examples, the above Tafel gradient may be 190mV / dec or less, 180mV / dec or less, 170mV / dec or less, or 165mV / dec or less.

[0152] Water electrolysis system

[0153] A water electrolysis electrode according to one embodiment of this disclosure can be configured as an element of a water electrolysis system.

[0154] In one embodiment, the water electrolysis system may be provided as an apparatus including a membrane electrode assembly. The membrane electrode assembly may include a separator, a cathode located in one of the spaces separated by the separator, an anode located in the other space separated by the separator, and an electrolyte that immerses or at least contacts the cathode and anode. A water electrolysis electrode according to one embodiment of the present disclosure may be provided as a cathode in a water electrolysis system.

[0155] In exemplary embodiments, the separator can function as an ion exchange membrane (a cation exchange membrane or anion exchange membrane; in one example, an anion exchange membrane). Exemplarily, the separator may be a porous polymer membrane, a porous ceramic membrane, or the like.

[0156] In exemplary embodiments, the anode may use a conductive substrate similar to that of the water electrolysis electrode, and the anode catalyst may be loaded onto the conductive substrate. The anode catalyst may be a noble metal catalyst known in the industry, such as iridium or palladium, or a non-noble metal catalyst, so as to be conductive without side reactions with the electrolyte and simultaneously exhibit low overpotential in the oxygen evolution reaction.

[0157] In exemplary embodiments, the electrolyte may be an alkaline electrolyte. While not necessarily limited thereto, examples of such electrolytes include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium bicarbonate, and potassium bicarbonate. While not necessarily limited thereto, the pH of the electrolyte may be 9 or higher, 9.5 or higher, 10 or higher, 10.5 or higher, 11 or higher, 11.5 or higher, or 12 or higher.

[0158] The water electrolysis system according to one embodiment may, for example, be preferably used in a water electrolysis device, a redox flow battery, or other fuel cell, but is not necessarily limited to these.

[0159] The embodiments of this disclosure will be further described below with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are merely illustrative of the present invention and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications to the embodiments are possible within the scope of this disclosure and the technical concept, and that such variations and modifications naturally fall within the scope of the appended claims.

[0160] Manufacturing example

[0161] (Examples)

[0162] (1) Manufacture of catalyst for water electrolysis electrodes

[0163] Vulcan XC-72R Carbon (Fuel cell store) was acid-treated with a mixed solution of 6M HNO3 and 6M H2SO4 for 24 hours, and then dried to obtain 8g of acid-treated dried carbon. The obtained 8g of carbon was dispersed in a 1:1 (v:v) mixed solution of propanol (Sigma-Aldrich) and distilled water, and then 100mL of pyrrole monomer (Sigma-Aldrich, 98%) was added to the above solution and stirred for 30 minutes. Meanwhile, 0.041 mol of iron chloride hexahydrate (Alfa Aesar) was quantified, dissolved in 50mL of distilled water, and added to the stirred suspension above, and stirred again for 4 hours to prepare an iron-doped polypyrrole-carbon composite (Fe-PPyCC).

[0164] Meanwhile, 0.062 mmol of nickel nitrate hexahydrate (Sigma-Aldrich) and 0.563 mmol of cobalt nitrate hexahydrate (Sigma-Aldrich) were quantified and dissolved in 20 mL of propanol (Sigma-Aldrich) to prepare a metal precursor solution. 330 mg of the iron-doped polypyrrole-carbon composite prepared as described above was added to the prepared metal precursor solution, and deposition was carried out while applying heat for a sufficient amount of time. Subsequently, the catalyst for the water electrolysis electrode was finally produced by thermal decomposition at 800°C for 1 hour under N2 conditions.

[0165] (2) Manufacture of water electrolysis electrodes

[0166] An ink was prepared by adding 10 mg of the water electrolysis electrode catalyst produced above and 40 μL of Nafion solution (5 wt.% Nafion solution, Sigma-Aldrich) to 1.5 mL of isopropanol (IPA) / distilled water in a 4:1 (v:v) ratio, and then uniformly mixing the mixture using an ultrasonic disperser.

[0167] Apply the ink prepared above to the substrate (GDL, Sigracet 39 BB, Fuel cell strore) at a rate of 2 mg / cm² using an air spray gun. 2 We then loaded the material and finally manufactured the water electrolysis electrode.

[0168] (Comparative Example 1)

[0169] (1) Manufacture of catalyst for water electrolysis electrodes

[0170] The catalyst for the water electrolysis electrode was prepared in the same manner as in the examples, except that a metal precursor solution was prepared by dissolving only 0.062 mmol of nickel nitrate hexahydrate in 20 mL of propanol, without adding cobalt nitrate hexahydrate.

[0171] (2) Manufacture of water electrolysis electrodes

[0172] A water electrolysis electrode was prepared in the same manner as in the examples, except that the catalyst for the water electrolysis electrode manufactured as described above was used.

[0173] (Comparative Example 2)

[0174] (1) Manufacture of catalyst for water electrolysis electrodes

[0175] The catalyst for the water electrolysis electrode was prepared in the same manner as in the examples, except that a metal precursor solution was prepared by dissolving only 0.563 mmol of cobalt nitrate hexahydrate in 20 mL of propanol, without adding nickel nitrate hexahydrate.

[0176] (2) Manufacture of water electrolysis electrodes

[0177] A water electrolysis electrode was prepared in the same manner as in the examples, except that the catalyst for the water electrolysis electrode manufactured as described above was used.

[0178] (Comparative Example 3)

[0179] (1) Manufacture of catalyst for water electrolysis electrodes

[0180] An iron-doped polypyrrole-carbon composite (Fe-PPyCC) prepared in the same manner as in the examples was used as a catalyst for a water electrolysis electrode without any further subsequent treatment.

[0181] (2) Manufacture of water electrolysis electrodes

[0182] A water electrolytic electrode was manufactured in the same manner as in the examples, except that the catalyst for water electrolysis electrodes described above was used.

[0183] (Comparative Example 4)

[0184] A water electrolysis electrode was prepared in the same manner as in the examples, except that a commercially available Pt / C catalyst (40% Platinum on Vulcan XC-72R, Fuel cell store) was used as the catalyst for the water electrolysis electrode.

[0185] Evaluation example

[0186] Evaluation Example 1. Evaluation of physicochemical catalytic properties

[0187] (1) TEM (Transmission Electron Microscopy) / EDS (Energy Dispersive x-ray Spectroscopy) mapping analysis

[0188] Figure 3 shows TEM images and EDS mapping results of the catalyst for the water electrolysis electrode in the example.

[0189] The water electrolysis electrode catalysts produced in the examples were observed and mapped using a high-resolution transmission electron microscope (JEM-2100F, JEOL LTD) equipped with a HAADF-STEM (High-Angle Annular Dark-Field Scanning Transmission Electron Microscope) detector, and the results are shown in Figure 3.

[0190] As shown in Figure 3, the analysis confirmed that nanoparticles with an average size of 25 nm were present in the water electrolysis electrode catalyst produced in the examples, and that nickel and cobalt existed in an alloy form with the same position. Furthermore, it was confirmed that iron monatoms were present not only in the carbon structure but also in the nickel-cobalt alloy particles.

[0191] (2) XRD (X-ray diffraction) analysis

[0192] Figure 4 is a graph showing the XRD pattern of the catalyst for the water electrolysis electrode in the example.

[0193] The metal crystal planes of the water electrolysis electrode catalysts produced in the examples were confirmed using an X-ray diffraction analyzer (PANalytical BV). Measurements were taken using Cu Kα radiation at 40kV and 100mA, with a scanning speed of 6° per minute at 0.01° intervals, covering only the 10-80° range. The measured patterns are shown in Figure 4.

[0194] The analysis results showed that the main peak shown in Figure 4 points to a nickel-cobalt alloy with a face-centered cubic (FCC) structure. Consequently, it was confirmed that nickel and cobalt alloys are present in the water electrolysis electrode catalyst produced in the examples, and thus it was confirmed that the nanoparticles in the examples are composed of nickel-cobalt alloy nanoparticles. However, according to the examples, iron doped into the nickel-cobalt alloy nanoparticles is present in trace amounts in the form of monatomic atoms and was therefore not detected in the pattern from the evaluation example above.

[0195] (3) Elemental content analysis

[0196] The metal element content of the water electrolysis electrode catalysts produced in the examples was analyzed by inductively coupled plasma (ICP) mass spectrometry. The metal element content of the water electrolysis electrode catalysts produced in the examples was analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-AES, NexION 300X, PerkinElmer), and the analysis results are shown in Table 1 below.

[0197] [Table 1]

[0198] On the other hand, the nitrogen content of the water electrolysis electrode catalyst produced in the examples was analyzed using an elemental analyzer. The nitrogen content of the catalyst was analyzed by melting the water electrolysis electrode catalyst produced in the examples in a helium gas atmosphere electric furnace at a constant power of 4500W and analyzing the released nitrogen gas through a TCD, and the analysis results are shown in Table 2 below.

[0199] [Table 2]

[0200] Evaluation Example 2. Evaluation of the electrochemical properties of electrodes

[0201] Figure 5 shows an example of a three-electrode system configured for electrochemical property evaluation.

[0202] Figure 6 is a graph showing the hydrogen generation reaction performance of the water electrolysis electrodes in Example 1, Comparative Example 3, and Comparative Example 4, as well as the current density vs. voltage curve.

[0203] The water electrolysis electrodes prepared in the examples and comparative examples were used as working electrodes 20, the Hg / HgO electrode as the reference electrode 30, and the graphite rod as the counter electrode 40, to form a three-electrode system as shown in Figure 5. Each electrode was placed in a 1M KCl solution 50.

[0204] The hydrogen evolution reaction performance was evaluated using each of the three electrode systems described above, each configured with the water electrolysis electrodes produced in the examples and comparative examples as the working electrodes. The hydrogen evolution reaction polarization of each three electrode system was measured and evaluated at room temperature with a scan rate of 5 mV / s. At this time, all measured values ​​were expressed as "vs RHE (reversible hydrogen electrode)", and the measurement results are shown in Figure 6 and Table 3 below.

[0205] [Table 3]

[0206] Referring to Figure 6 and Table 3 above, the current density is 200 mA / cm². 2When comparing the performance of the reference hydrogen evolution reaction, the catalyst in the example showed performance at a similar level to the catalyst in Comparative Example 4, which is a commercial platinum catalyst, with a current density of 300 mA / cm². 2 When comparing the performance of the reference hydrogen evolution reaction, it was confirmed that the catalyst in the example had superior hydrogen evolution reaction performance compared to the catalyst in Comparative Example 4, which was a commercially available platinum catalyst.

[0207] Specifically, when using a water electrolysis electrode to which the catalyst of the example is applied, the current is 300 mA / cm². 2 It was confirmed that only an overvoltage of 0.54V was required to obtain the current density, which corresponds to an overvoltage approximately 0.07V lower than when using the catalyst of Comparative Example 4, which is a commercial platinum catalyst. This suggests that the catalyst of the example has superior performance compared to the commercial platinum catalyst in the hydrogen evolution reaction.

[0208] Figure 7 is a graph showing the hydrogen generation reaction performance of the water electrolysis electrodes in Example, Comparative Example 1, Comparative Example 3, and Comparative Example 4, as shown by the overpotential vs. log current density curve.

[0209] On the other hand, the slopes of the Tafel plots for the examples and comparative examples in Figure 7 are shown in Table 4 below.

[0210] [Table 4]

[0211] Referring to Figure 7 and Table 4 above, the catalyst in the example showed a gradient approximately 45 mV / dec smaller than that of the catalyst in Comparative Example 4, which is a commercial platinum catalyst. This suggests that the catalyst in the example has superior reaction kinetics compared to the commercial platinum catalyst in the hydrogen evolution reaction.

[0212] As a result of the evaluation, it was confirmed that a water electrolysis electrode using the catalyst for water electrolysis according to one embodiment of the present disclosure has superior hydrogen evolution reaction performance compared to an electrode using a commercial platinum catalyst. Referring to (3) of Evaluation Example 1 above, considering that the catalyst of the example may have a transition metal content at 1 / 4 the level of a commercial platinum catalyst, it was confirmed that the catalyst for water electrolysis according to one embodiment of the present disclosure can provide a non-precious metal catalyst that has superior hydrogen evolution reaction performance compared to conventional commercial precious metal catalysts even with a low amount of transition metal loading.

[0213] Figure 8 shows an example of the surface structure of a catalyst for a water electrolysis electrode in Comparative Example 3. As can be seen from the example of the surface structure shown in Figure 8, unlike the example, the surface of the carbon structure 300 in the catalyst of Comparative Example 3 does not need to have alloy nanoparticles supported on it.

[0214] It was confirmed that the catalyst in the example exhibited superior hydrogen evolution reaction performance compared to the catalysts in the remaining comparative examples.

[0215] The results described above are attributed to the fact that, in one embodiment of the present disclosure, the catalyst for water electrolysis electrodes can induce a different reaction specificity than before through nickel-cobalt-iron interactions by introducing iron monatoms into the nickel-cobalt alloy nanoparticles that act as the main active sites of the catalyst. Furthermore, it is also attributed to the fact that iron monatoms doped on the surface of carbon structures surrounding the nickel-cobalt alloy nanoparticles can contribute to the partial improvement in performance by interacting with the alloy nanoparticles in addition.

[0216] The above is merely an example of applying the principles of this disclosure, and other configurations may be included as long as they do not fall outside the scope of this disclosure. [Explanation of Symbols]

[0217] 10 Catalyst for water electrolysis electrodes 100 1st element 200 Second element 300 Carbon Structures 400 alloy nanoparticles

Claims

1. A carbon structure doped with the first and second elements, The above-mentioned first element is used to dope alloy nanoparticles, and the above-mentioned first element is used to dope alloy nanoparticles, The above alloy nanoparticles are supported on the surface of the above carbon structure. The first element mentioned above is iron (Fe), a catalyst for water electrolysis electrodes.

2. The above carbon structure is A catalyst for a water electrolysis electrode according to claim 1, comprising at least one selected from the group consisting of carbon black, carbon nanotubes, carbon nanofibers, carbon nanoribbons, fullerenes, graphene, graphene nanoplates, and graphite.

3. The catalyst for a water electrolysis electrode according to claim 1, wherein the second element is nitrogen.

4. The catalyst for a water electrolysis electrode according to claim 1, wherein the alloy nanoparticles are nickel-cobalt (Ni-Co) alloy nanoparticles.

5. The catalyst for a water electrolysis electrode according to claim 4, wherein the nickel-cobalt alloy nanoparticles contain an excess amount of cobalt relative to nickel.

6. The catalyst for a water electrolysis electrode according to claim 1, wherein the catalyst for the water electrolysis electrode is an Fe-N-C system catalyst on which iron (Fe)-doped nickel-cobalt alloy nanoparticles are supported.

7. The catalyst for a water electrolysis electrode according to claim 1, wherein the above-mentioned first element is contained in an amount of 0.01% to 0.10% by weight based on the total weight of the catalyst for the water electrolysis electrode.

8. The process involves contacting a carbon precursor with a solution of a first element precursor to form a carbon composite doped with the first element, The step includes impregnating a carbon composite doped with the above-mentioned first element into a metal precursor solution, The first element mentioned above is iron (Fe), A method for producing a catalyst for a water electrolysis electrode, comprising the above-mentioned metal precursor solution containing two or more different transition metal precursors.

9. The above carbon precursor is A method for producing a catalyst for a water electrolysis electrode according to claim 8, comprising at least one selected from the group consisting of carbon black, carbon nanotubes, carbon nanofibers, carbon nanoribbons, fullerenes, graphene, graphene nanoplates, and graphite.

10. The above-mentioned first element precursor solution is A method for producing a catalyst for a water electrolysis electrode according to claim 8, comprising at least one selected from the group consisting of iron chloride, iron nitrate, iron acetate, iron sulfate, iron trifluoromethanesulfonate, iron citrate, iron acetylacetoneate, and iron pyrophosphate, or a mixture thereof.

11. The step of forming a carbon composite doped with the above first element is: A method for producing a catalyst for a water electrolysis electrode according to claim 8, wherein the carbon precursor is treated with nitrogen and then brought into contact with the first element precursor solution.

12. The above metal precursor solution is A method for producing a catalyst for a water electrolysis electrode according to claim 8, comprising a nickel (Ni) precursor and a cobalt (Co) precursor.

13. The above method for producing a catalyst for a water electrolysis electrode is as follows: The method for producing a catalyst for a water electrolysis electrode according to claim 8, further comprising the step of heat-treating the metal precursor solution impregnated with the carbon composite doped with the first element in an inert atmosphere.

14. The above heat treatment step is, A method for producing a catalyst for a water electrolysis electrode according to claim 13, comprising heat treatment at a temperature of 600°C to 1000°C for 30 minutes to 2 hours.

15. Substrate and The above substrate contains a catalyst for a water electrolysis electrode, The above-mentioned catalyst for water electrolysis electrodes is The present invention comprises a carbon structure doped with a first element and a second element, and alloy nanoparticles doped with the first element. The above alloy nanoparticles are supported on the surface of the above carbon structure. The first element mentioned above is iron (Fe), in a water electrolysis electrode.

16. The water electrolysis electrode according to claim 15, wherein the alloy nanoparticles are nickel-cobalt (Ni-Co) alloy nanoparticles.

17. The water electrolysis electrode according to claim 15, wherein the catalyst for the water electrolysis electrode is an Fe-N-C system catalyst on which iron (Fe)-doped nickel-cobalt alloy nanoparticles are supported.

18. The water electrolytic electrode according to claim 15, wherein the above-mentioned first element is contained in an amount of 0.01% to 0.10% by weight based on the total weight of the catalyst for the water electrolytic electrode.

19. The loading amount of the above-mentioned catalyst for water electrolysis electrodes is 0.1 mg / cm². ２ ~5.0 mg / cm ２ The water electrolysis electrode according to claim 15.

20. The water electrolysis electrode according to claim 15, wherein the Tafel slope is 200 mV / dec or less.

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