Electrochemical insoluble catalyst electrode and method for manufacturing same

Abstract

An electrochemical insoluble catalyst electrode, according to one embodiment of the present disclosure, may comprise: a support substrate; and a catalyst layer positioned on the support substrate, wherein the catalyst layer may include: a conductive support including niobium-doped titanium oxide (Nb:TiO2) nanoparticles; and a catalyst formed by supporting a transition metal or a transition metal oxide on the conductive support in the form of a single atom or a cluster, wherein the transition metal or the transition metal oxide may be formed of any one selected from iridium (Ir) and platinum (Pt). According to this configuration, it is possible to provide an electrochemical insoluble catalyst electrode having high catalytic activity while having low manufacturing costs.

Description

Electrochemical insoluble catalyst electrode and method for preparing the same

[0001] The present invention relates to an electrochemical insoluble catalyst electrode and a method for manufacturing the same, and more particularly, to a catalyst electrode that generates hypochlorous acid through an electrochemical method under extremely low salt conditions and a method for manufacturing the same.

[0002] Recently, the efficient use of water has been emphasized, and the demand for new water treatment or recycling technologies to meet strengthened water quality regulations and water demand is rapidly expanding, so the water industry market is expected to expand.

[0003] That is, environmental legal regulations are being strengthened to preserve long-term, stable water resources, and accordingly, the development of efficient and reliable water treatment / water recycling systems is required.

[0004] For this purpose, electrochemical treatment technology is attracting attention as a technology that can process more efficiently than existing methods.

[0005] Electrochemical methods are not affected by external factors such as biotoxicity, temperature, and dissolved oxygen, and can decompose, sterilize, and disinfect difficult-to-decompose organic substances through the generation of strong oxidants. They also allow for short-term treatment processes and miniaturization of the process.

[0006] It also has the great advantage of being able to produce strong oxidizing agents without the use of chemical additives that may generate secondary waste.

[0007] The basic operating principle of an electrochemical system is the oxidation-reduction reaction at the anode and cathode, which are the core components of the chemical substances contained in the water to be utilized.

[0008] For example, if a chemical containing Cl, which acts as an electrolyte, is present, the Cl may be oxidized at the anode to produce chlorine and simultaneously generate oxygen.

[0009] Additionally, water can be reduced at the cathode to produce hydrogen, and the main redox reactions are as follows:

[0010] anode

[0011] 2Cl - → Cl2+ 2e -

[0012] H2O → O2+ 4H + + 4e -

[0013] cathode

[0014] 2H2O + 2e - → H2+ 2OH -

[0015] The chlorine generated by the oxidation reaction is hypochlorous acid (HClO) or hypochlorite ion (ClO) depending on the pH of the water. - ) comes into existence.

[0016] These chlorine components are called free chlorine and are mainly HClO and ClO at pH 6.5 to 8. - It exists in the form of

[0017] Cl 2 + H2O → H + + Cl - + HClO (pH4.6 at 25℃)

[0018] HClO ↔ H + + ClO (pH7.5 at 25℃)

[0019] Among these compounds, HClO is called active chlorine and has strong oxidizing and disinfecting power.

[0020] Theoretically, most organic substances undergo electrochemical oxidation, but the active application of electrochemical methods in general industrial fields has not been activated due to problems such as a decrease in electrode activity due to the potential at which oxygen is generated and the dissolution of the electrode itself.

[0021] However, the continuously developed insoluble oxide electrode (DSA, Dimensionally Stable Anode) has a relatively low overvoltage for oxygen generation, and the organic matter itself is oxidized before and after the potential at which oxygen is generated, and it is known that the organic matter itself in the target wastewater can be burned by basically changing the organic matter into carbon dioxide and water. In addition, the surface of this electrode itself is a type of ceramic, so it can maintain its health for a much longer time than a general metal electrode, and it has been known to be effective in water treatment due to its excellent characteristics as an electrode.

[0022] Insoluble oxide catalyst electrodes are mainly made by coating a titanium (Ti) substrate with platinum group metal oxides such as iridium (Ir), ruthenium (Ru), platinum (Pt), and palladium (Pd). However, electrodes made only of these metal oxides dissolve when used for a long time, making it difficult to maintain the electrode's integrity.

[0023] Therefore, in order to maintain appropriate electrode activity and have a long electrode life, auxiliary metal oxides such as tin (Sn), titanium (Ti), tantalum (Ta), cerium (Ce), zirconium (Zr), and iridium (Ir) (in the case of RuO2) are added to manufacture the electrode oxides, which are used as stabilizers or regulators for the electrode oxides.

[0024] The manufacturing method of a commonly manufactured insoluble electrode is to remove contaminants from the surface of a titanium (Ti) substrate in a mesh or flat shape, then perform an etching process through acid treatment, etc., or to provide an appropriate surface roughness through a sandblasting method, and then apply the above-mentioned metal chloride solution and form a metal oxide layer on the surface of the titanium (Ti) substrate through a drying and heat treatment process.

[0025] Additionally, repeated coating processes and heat treatment processes using iridium (Ir) and ruthenium (Ru) solutions are performed to control the thickness of the metal oxide layer.

[0026] However, in order to improve the performance of an insoluble electrode, it is necessary to comprehensively evaluate the characteristics of the entire electrode, that is, the material and electrochemical characteristics and the lifespan of the electrode, rather than complementing only one characteristic that affects the electrode surface, and to find a method that satisfies all of these simultaneously.

[0027] Accordingly, a method for manufacturing an electrode by forming a catalyst layer based on a platinum group metal oxide, for example, iridium-platinum (Ir-Pt), has been developed.

[0028] However, when only platinum group metal oxides are used, there is a problem in that the price of the catalyst electrode is high because the price of platinum group metal oxides is high, and there is a possibility that the platinum group metals will be eluted when used for a long time.

[0029] Accordingly, research is being conducted to maximize the efficiency of insoluble catalyst electrodes, especially the anode, and simplify the manufacturing process to reduce costs.

[0030] As an example of the above method, Korean Patent Publication No. 10-1741401 (hereinafter referred to as “prior patent 1”) discloses a method for manufacturing an electrode, which comprises forming a catalyst layer including a platinum group metal oxide, for example, iridium-tantalum (Ir-Ta), on a titanium (Ti) substrate to form a first oxide layer (IrO2-TaOX), and then forming a nano titanium dioxide (TiO2) layer on the first metal oxide layer to form a second metal oxide layer.

[0031] In the above prior art patent 1, the first metal oxide layer acts as a catalyst, and the second metal oxide layer acts to protect the first metal oxide layer and improve the life of the electrode.

[0032] However, since the above-mentioned prior art patent 1 forms a second metal oxide layer using titanium particles that have been synthesized, there is a problem in that titanium particles for forming the second metal oxide layer must be synthesized separately.

[0033] In addition, since the first metal oxide layer is formed using a material different from the titanium substrate, the adhesive force between the first metal oxide layer and the titanium substrate is weak, and the particle size of the catalyst in the first metal oxide layer is large, so the reaction surface area of ​​the catalyst is formed small, which causes a problem of low chlorine generation reaction efficiency.

[0034] Additionally, there is a problem that the manufacturing cost of catalyst electrodes is high due to the large amount of platinum group metals (iridium, tantalum).

[0035] And as another example of the above-mentioned method, Korean Patent Publication No. 10-1148111 (hereinafter referred to as “prior patent 2”) discloses a method for manufacturing an electrode by forming a catalyst layer based on a platinum group metal oxide, for example, ruthenium-titanium (Ru-Ti), on a titanium substrate.

[0036] However, since the catalyst layer of the above-mentioned prior art patent 2 uses ruthenium (Ru), there is a problem that it cannot be used under extremely low salt conditions, such as tap water containing Cl at a concentration of 5 ppm to 50 ppm.

[0037] In addition, there is a problem that the particle size of the catalyst in the first metal oxide layer is large, so that the reaction surface area of ​​the catalyst is formed small, and thus the efficiency of the chlorine generation reaction is low.

[0038] Meanwhile, US Patent Application Publication No. US 2021 / 0016256 (hereinafter referred to as Prior Art 3) discloses a support comprising a refractory material having a surface area of ​​50 m2 / g to 100 m2 / g or more, for example, silica, alumina, magnesia, zirconia, cordierite, mullite, perovskite, or any combination thereof; a plurality of nano-scale metal oxide clusters bonded to the support and comprising CeOx, CoOx, FeOx TiOx, CuOx, NiOx, MnOx, NbOx, ZrOx, or any combination thereof, and formed in a size of 0.5 nm to 10 nm; And a nanocomposite catalyst comprising one or more metal atoms, for example, Pt, Pd, Rh, Au, Ru, Ir, or any combination thereof, bonded to each nanoscale metal oxide cluster, wherein the nanocomposite catalyst is used to induce reactions such as oxidation of carbon monoxide, transport of water gas (a mixed gas of hydrogen and carbon monoxide), reforming of carbon dioxide and methanol, and oxidation of natural gas.

[0039] However, the nanocomposite catalyst of the above-mentioned prior art patent 3 is difficult to use as an electrode because the support is composed of a refractory material with low conductivity.

[0040] Therefore, the nanocomposite catalyst of prior art patent 3 cannot be used as a catalyst electrode for generating hypochlorous acid through an electrochemical method under extremely low salt conditions.

[0041] [Prior Art Literature]

[0042] [Patent Document]

[0043] Prior patent 1: Republic of Korea Patent Publication No. 10-1741401

[0044] Prior patent 2: Republic of Korea Patent Publication No. 10-1148111

[0045] Prior patent 3: U.S. Patent Application Publication No. US 2021 / 0016256

[0046] The technical problem to be solved by the present specification is to provide an electrochemical insoluble catalyst electrode and a method for manufacturing the same that can solve at least one of the problems described above.

[0047] Another technical problem to be solved by the present specification is to provide a metal and metal oxide atom-controlled catalyst electrode having high chlorine generation characteristics for an electrochemical chlorine generation reaction and a method for manufacturing the same.

[0048] Another technical challenge that the present specification seeks to address is to provide an electrochemically insoluble catalyst electrode that generates hypochlorous acid through an electrochemical method under extremely low-salinity conditions such as tap water, and a method for manufacturing the same.

[0049] Another technical challenge that the present invention seeks to address is to provide single-atom and nanocluster catalysts in which single-atom and sub-nanometer sized metals exist in a form intermixed in a conductive oxide network, and a method for preparing the same.

[0050] Another technical challenge that this specification seeks to address is to provide an electrochemically insoluble catalyst electrode and a method for manufacturing the same, which can reduce manufacturing costs.

[0051] Another technical challenge that the present specification seeks to address is to provide an electrochemically insoluble catalyst electrode with improved reactivity and durability and a method for manufacturing the same.

[0052] The technical problems to be achieved in this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which this specification pertains from the description below.

[0053] An electrochemically insoluble catalyst electrode according to one embodiment of the present disclosure may include a support substrate; and a catalyst layer positioned on the support substrate, wherein the catalyst layer may include a conductive support including niobium-doped titanium oxide (Nb:TiO2) nanoparticles; and a catalyst formed by supporting a transition metal or a transition metal oxide on the conductive support in the form of a single atom or a cluster, wherein the transition metal or the transition metal oxide may be formed of one selected from iridium (Ir) and platinum (Pt).

[0054] According to this configuration, the catalyst layer is formed as a porous structure having a plurality of pores having a size of several tens of nm to several μm, so that the catalyst surface area of ​​the catalyst electrode can be increased due to the porous network of niobium oxide, which is a conductive oxide.

[0055] Furthermore, since the porous network is loaded with single-atom or sub-nanometer-sized metal and metal oxide catalysts, it exhibits catalytic activity comparable to that of conventional precious metal-based catalysts, while maintaining a very low total precious metal content of less than 5%, thereby reducing manufacturing costs. Consequently, it offers exceptional industrial competitiveness.

[0056] In addition, the single-atom or sub-nanometer sized iridium (Ir) or platinum (Pt)-based catalysts included in the present specification have high atomic utilization efficiency compared to bulk catalysts, so that high chlorine generation efficiency can be obtained even with a small amount of metal.

[0057] In addition, the electrode structure presented in this specification can achieve high chlorine generation efficiency under extremely low salinity conditions such as tap water by controlling the overall morphology of the electrode as well as by simply changing the composition of the catalyst.

[0058] In an embodiment of the present disclosure, the niobium-doped titanium oxide (Nb:TiO2) nanoparticles may each have a size of 4 nm to 40 nm.

[0059] Nanoparticles having the above size can effectively perform the role of a support while securing the maximum specific surface area on which the catalyst can be supported.

[0060] The above cluster may have a size of 5 nm or less.

[0061] By forming the cluster size to be less than 5 nm, the mass activity, which means the current according to the amount of catalyst, can be effectively increased.

[0062] The above niobium-doped titanium oxide (Nb:TiO2) nanoparticles may each have an anatase structure.

[0063] Titanium oxide nanoparticles can have three structures: anatase, rutile, and brookite. The anatase structure has superior photocatalytic activity in photodecomposing pollutants in water or air compared to the rutile and brookite structures, and thus can increase catalytic activity.

[0064] The conductive support on which the catalyst is supported is M a Nb b Ti c It can have a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

[0065] When the conductive support on which the catalyst is supported is formed to have the above composition, a high chlorine generation efficiency can be obtained even with a small amount of precious metal.

[0066] The above support substrate can be formed of titanium.

[0067] According to this configuration, the adhesion between the catalyst layer and the titanium substrate is improved, so the durability of the catalyst electrode is increased even without forming a separate protective layer to protect the catalyst layer.

[0068] The electrochemically insoluble catalyst electrode of the above-described configuration can be manufactured by a manufacturing method including the steps of: treating the surface of a supporting substrate; preparing a conductive support comprising niobium-doped titanium oxide (Nb:TiO2) nanoparticles; preparing a support solution comprising a transition metal precursor selected from iridium (Ir) and platinum (Pt); preparing a coating solution by supporting the niobium-doped titanium oxide (Nb:TiO2) nanoparticles in the support solution; coating the coating solution on the supporting substrate to form a coating layer; and sintering the coating layer to form a catalyst layer in which a transition metal or transition metal oxide composed of iridium or platinum is supported on the conductive support as a catalyst in the form of a single atom or cluster.

[0069] According to this configuration, the electrolyte (Cl - ) can be manufactured to increase the efficiency of the chlorine generation reaction in extremely low-salinity tap water containing a small amount of chlorine, for example, tap water having a Cl concentration of 5 ppm to 50 ppm.

[0070] And since the catalyst layer can be formed with a porous structure having a plurality of pores having a size of several tens of nm to several μm, the catalyst surface area of ​​the catalyst electrode can be increased due to the porous network of niobium oxide, which is a conductive oxide.

[0071] And, since the porous network can support a metal or metal oxide catalyst of single-atom or sub-nanometer size, it is possible to manufacture an electrochemically insoluble catalyst electrode having a catalytic activity comparable to that of a conventional precious metal-based catalyst, while having a very low total precious metal content of 5% or less, thereby reducing the manufacturing cost.

[0072] In addition, the single-atom or sub-nanometer sized iridium (Ir) or platinum (Pt)-based catalysts included in the present specification have high atomic utilization efficiency compared to bulk catalysts, so that high chlorine generation efficiency can be obtained even with a small amount of metal.

[0073] In addition, the electrode structure presented in this specification can achieve high chlorine generation efficiency under extremely low salinity conditions such as tap water by controlling the overall morphology of the electrode as well as by simply changing the composition of the catalyst.

[0074] The above support substrate may be made of a titanium substrate, and the step of treating the surface of the support substrate may include a step of sandblasting the surface of the support substrate to form a surface roughness of the support substrate of 1 µm to 5 µm; and a step of etching the surface of the support substrate at room temperature with 0.1 M to 1.0 M sulfuric acid.

[0075] According to this configuration, since the conductive support is formed with titanium oxide, which is the same material as the titanium substrate, the thermal expansion coefficients of the surface of the titanium substrate and the catalyst layer are formed to be similar.

[0076] Therefore, since the adhesion between the catalyst layer and the titanium substrate is improved, the durability of the catalyst electrode is increased even without forming a separate protective layer to protect the catalyst layer.

[0077] And, by performing an etching step using sulfuric acid, alumina particles remaining on the surface of the titanium substrate after being used in sandblasting treatment can be effectively removed.

[0078] The above niobium-doped titanium oxide (Nb:TiO2) nanoparticles can be manufactured using a hydrothermal synthesis method.

[0079] Using a hydrothermal synthesis method, the niobium-doped titanium oxide (Nb:TiO2) nanoparticles can be formed with a size of 4 nm to 40 nm, and can be formed with an anatase structure.

[0080] Nanoparticles having the above size can effectively perform the role of a support while securing the maximum specific surface area on which the catalyst can be supported.

[0081] In addition, the anatase structure has excellent photocatalytic activity in photodecomposing pollutants present in water or air compared to the rutile structure and brookite structure, so the catalytic activity can be increased.

[0082] When manufacturing a conductive support using a hydrothermal synthesis method, titanium isopropoxide or titanium butoxide can be used as a titanium precursor, niobium(V) chloride or niobium ethoxide can be used as a niobium precursor, and a solution containing an organic solvent including either ethanol or isopropyl alcohol (2-propanol) and water in a ratio of 1:1 to 4:1 can be used as a synthesis solution.

[0083] And the pH of the above synthetic solution can be formed in the range of 0 to 2.

[0084] The amount of niobium doped into titanium oxide nanoparticles can vary depending on the ratio of the titanium precursor to the niobium precursor.

[0085] And the size of niobium-doped titanium oxide (Nb:TiO2) nanoparticles can vary depending on the type and pH of the synthesis solution.

[0086] In the step of preparing a support solution, the support solution can be prepared by mixing an organic solvent including one of ethanol and isopropyl alcohol (2-propanol) and water in a ratio of 50:50 to 100:0.

[0087] And the pH of the above-mentioned solution can be formed in the range of 2 to 5.

[0088] The amount of noble metal precursor loaded on niobium-doped titanium oxide (Nb:TiO2) nanoparticles may vary depending on the type and pH of the loading solution.

[0089] The conductive support on which the catalyst is supported is M a Nb b Ti c It can have a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

[0090] By controlling the atomic ratio (at%) of niobium-doped titanium oxide (Nb:TiO2) nanoparticles compared to a precious metal precursor and through an annealing process, the size of the metal and metal oxide catalyst supported on the surface of the niobium-doped titanium oxide (Nb:TiO2) nanoparticles can be controlled, and clusters can be formed with a size of 5 nm or less.

[0091] By forming the cluster size to be less than 5 nm, the mass activity, which means the current according to the amount of catalyst, can be effectively increased.

[0092] The step of forming the above catalyst layer may include two annealing steps.

[0093] For example, the step of forming the catalyst layer may include a first annealing step of annealing the coating layer at a temperature of 200°C to 300°C, a cleaning step of cleaning the coating layer using dimethyl sulfoxide or distilled water, and a second annealing step of annealing the coating layer at a temperature of 450°C to 500°C.

[0094] The monoatomic metal and metal oxide catalysts prepared through two-step annealing have a 10 mA / cm higher conductivity than the monoatomic metal and metal oxide catalysts prepared through only one annealing. 2 It exhibits an overvoltage as low as 13 mV at a current density of .

[0095] The single-atom catalysts in the form of metal and metal oxides produced through only one annealing and the single-atom catalysts in the form of metal and metal oxides produced through two-step annealing have less than 1 mM chloride ion (Cl - ) When comparing the faradaic efficiency values ​​under ultra-low salt conditions with a concentration of 0.38%, the monoatomic metal and metal oxide catalysts produced through two-step annealing show a faradaic efficiency of 0.38% or more compared to the monoatomic metal and metal oxide catalysts produced through only one annealing.

[0096] According to the present specification, a metal and metal oxide atom-controlled catalyst electrode having high chlorine generation characteristics for an electrochemical chlorine generation reaction and a method for manufacturing the same can be provided.

[0097] In addition, an electrochemical insoluble catalyst electrode that generates hypochlorous acid through an electrochemical method under extremely low-salinity conditions such as tap water and a method for manufacturing the same can be provided.

[0098] In addition, it is possible to provide a single-atom and nano-cluster catalyst and a method for manufacturing the same, wherein single-atom and sub-nanometer sized metals exist in a form mixed in a conductive oxide network.

[0099] And, an electrochemical insoluble catalyst electrode and a method for manufacturing the same can be provided, which can reduce manufacturing costs.

[0100] And it is possible to provide an electrochemically insoluble catalyst electrode with improved reactivity and durability and a method for manufacturing the same.

[0101] The effects that can be obtained from this specification are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the technical field to which this specification belongs from the description below.

[0102] The accompanying drawings, which are incorporated in and are intended to aid in the understanding of the present specification and are a part of the detailed description, provide embodiments of the present specification and, together with the detailed description, explain the technical features of the present specification.

[0103] Figure 1 is a conceptual diagram showing a schematic configuration of an electrochemical insoluble catalyst electrode according to the present specification.

[0104] Figure 2 is a block diagram schematically showing a method for manufacturing an electrochemically insoluble catalyst electrode according to the present specification.

[0105] Figure 3 is a graph showing the XRD analysis results of niobium-doped titanium oxide (Nb:TiO2) nanoparticles and niobium-free titanium oxide nanoparticles.

[0106] Figure 4 is a HAADF-STEM image of single atoms and nanoclusters in the form of metal and metal oxide depending on the ratio of iridium precursor and niobium-doped titanium oxide (Nb:TiO2) nanoparticles.

[0107] FIG. 5 is a graph showing the results of XANES (X-ray Absorption fine structure) and EXAFS (Extended X-ray Absorption Fine Structure) analyses showing that the catalyst layer provided in the catalyst electrode of the present embodiment includes a transition metal atom.

[0108] Figure 6 is a SEM (scanning electron microscopy) image showing that the catalyst layer provided in the catalyst electrode of the present embodiment has a porous structure.

[0109] Figure 7 shows the 600 mM chloride ion (Cl) of the catalyst layer provided in the catalyst electrode of the present embodiment. - ) is a graph showing electrochemical chlorine generation activity data at the catalyst electrode according to the form of single atoms and nanoclusters under concentration conditions and a graph showing mass activity.

[0110] FIG. 8 is a graph showing the electrically active surface area (ECSA) measurement data of the catalyst layer provided in the catalyst electrode of the present embodiment and a graph showing the double layer capacitance.

[0111] Figure 9 shows the chlorine ion (Cl) content of 1 mM or less in the catalyst layer provided in the catalyst electrode of the present embodiment. - ) is a graph showing the electrochemical chlorine generation selectivity data at the electrode according to the single-atom and nano-cluster forms under concentration conditions.

[0112] Figure 10 is a HAADF-STEM image of a catalyst layer manufactured through two-step annealing of the present embodiment.

[0113] Figure 11 shows the results of a catalyst layer manufactured through only one annealing and a catalyst layer manufactured through two-step annealing of the present embodiment with 600 mM chloride ion (Cl -) is a graph showing electrochemical chlorine generation activity data under concentration conditions.

[0114] Figure 12 shows the chloride ion (Cl) content of 1 mM or less in a catalyst layer manufactured through only one annealing and a catalyst layer manufactured through two-step annealing of the present embodiment. - ) is a graph showing the electrochemical chlorine generation selectivity data under concentration conditions.

[0115] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components are given the same reference numbers and redundant descriptions thereof will be omitted.

[0116] The suffixes "assembly" and "part" used for components in the following description are given or used interchangeably only for the convenience of writing specifications, and do not have distinct meanings or roles in themselves.

[0117] In addition, when describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiments disclosed in this specification, the detailed description is omitted.

[0118] In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of this specification.

[0119] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0120] When it is said that a component is "coupled to" or "in contact with" another component, it should be understood that it may be directly coupled to or in direct contact with that other component, but there may also be other components present in between.

[0121] On the other hand, when it is said that a component is "directly coupled" to or "in direct contact with" another component, it should be understood that there are no other components in between.

[0122] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0123] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0124] Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components are given the same reference numbers and redundant descriptions thereof will be omitted.

[0125] Figure 1 is a conceptual diagram showing a schematic configuration of an electrochemical insoluble catalyst electrode according to the present specification.

[0126] Figure 2 is a block diagram schematically showing a method for manufacturing an electrochemically insoluble catalyst electrode according to the present specification.

[0127] As illustrated in FIG. 1, an electrochemically insoluble catalyst electrode (100) according to an embodiment of the present specification may include a titanium substrate (110) and a catalyst layer (120) positioned on the titanium substrate (110).

[0128] The surface of the titanium substrate (110) is surface-treated through a pretreatment process.

[0129] That is, the surface of the titanium substrate (110) can be processed to a surface roughness of 1 μm to 5 μm by the sandblasting method, and then etched with 0.1 M to 1.0 M sulfuric acid at room temperature.

[0130] When an etching process using sulfuric acid is performed, alumina particles remaining on the surface of the titanium substrate (110) among the alumina particles used in the sandblasting method can be effectively removed.

[0131] It is preferable to use American Society for Testing and Materials (ASTM) grade 1 or 2 as the titanium substrate (110).

[0132] After the etching process using sulfuric acid, the titanium substrate (110) can be dried by a drying process.

[0133] The catalyst layer (120) according to the present specification may include a conductive support (121) including niobium-doped titanium oxide (Nb:TiO2) nanoparticles, and a catalyst (123) formed by supporting a transition metal or transition metal oxide on the conductive support (121) in the form of a single atom or nano cluster.

[0134] Here, "monoatomic" refers to a form in which a transition metal oxide is dispersed and supported on a support in the form of atomic units, i.e., single atoms. Monoatomic may be an expression equivalent to a single atom.

[0135] And "cluster" means a form formed by several to several dozen single atoms clumping together.

[0136] The above transition metal or the above transition metal oxide may be composed of one selected from iridium (Ir) and platinum (Pt).

[0137] Referring to FIG. 3, it can be seen that the titanium-doped titanium oxide nanoparticles (121) have an anatase structure, and that the XRD peaks shift to the left as niobium is doped.

[0138] FIG. 5 is a graph showing the results of XANES (X-ray Absorption fine structure) and EXAFS (Extended X-ray Absorption Fine Structure) analyses showing that the catalyst layer provided in the catalyst electrode of the present embodiment includes a transition metal atom.

[0139] Referring to FIG. 5, it can be seen that iridium (Ir) is reduced compared to iridium dioxide (IrO2) having an oxidation number of +4, and is bonded to oxygen (O) within the support, rather than forming an iridium-iridium (Ir-Ir) bond as in iridium foil (Ir foil) or an iridium-oxygen-iridium (Ir-O-Ir) bond as seen in iridium dioxide (IrO2).

[0140] Therefore, it can be seen that the metal and metal oxide catalysts in the form of a single atom exhibit metal-oxygen bonding.

[0141] Referring to FIG. 1 and FIG. 6, the catalyst layer (120) can be formed into a porous structure having a plurality of pores (125) having a size of several tens of nm to several μm.

[0142] Figure 6 is a SEM (scanning electron microscopy) image showing that the catalyst layer provided in the catalyst electrode of the present embodiment has a porous structure.

[0143] Therefore, the specific surface area of ​​the catalyst layer (120) can be increased due to the porous network of niobium oxide, which is a conductive oxide.

[0144] Furthermore, since the porous network is loaded with a metal or metal oxide catalyst (123) of single-atom or sub-nanometer size, it has a catalytic activity comparable to that of existing precious metal-based catalysts, while the total precious metal content is very low at 5% or less, thereby reducing manufacturing costs. Therefore, it is highly industrially competitive.

[0145] In addition, the single-atom or sub-nanometer sized iridium (Ir) or platinum (Pt)-based catalyst (123) included in the present specification has a high atomic utilization efficiency compared to bulk catalysts, so that high chlorine generation efficiency can be obtained even with a small amount of metal.

[0146] The structure of the catalyst electrode (100) presented in this specification can achieve high chlorine generation efficiency under extremely low salt conditions such as tap water by controlling the overall morphology of the catalyst electrode as well as by simply changing the composition of the catalyst (123).

[0147] As illustrated in Fig. 1, niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121), i.e., conductive carriers (121), may each have a size (S1) of 4 nm to 40 nm.

[0148] Nanoparticles (121) having the above size (S1) can effectively perform the role of a support while securing the maximum specific surface area on which the catalyst (123) can be supported.

[0149] In this regard, in order for the nanoparticles (121) to effectively perform the role of a support, it is preferable to form the size (S1) of the nanoparticles (121) to be 4 nm or more, and in order to secure the maximum specific surface area on which the catalyst (123) is to be supported, it is preferable to form the size (S1) of the nanoparticles (121) to be 40 nm or less.

[0150] Referring to FIG. 4, the catalyst (123) can be supported on nanoparticles (121) in the form of a single atom or nano cluster, and the catalyst (123) supported on nanoparticles (121) in the form of a nano cluster can have a size (S2) of 5 nm or less.

[0151] Figure 4 is a HAADF-STEM image of single atoms and nanoclusters in the form of metal and metal oxide depending on the ratio of iridium precursor and niobium-doped titanium oxide (Nb:TiO2) nanoparticles.

[0152] Referring to FIG. 4, it is shown that a brightly shining platinum (Pt) or iridium (Ir)-based metal and metal oxide catalyst (123) is supported in the form of a small single atom or nano cluster on niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121).

[0153] And the size of the catalyst (123) can be controlled by adjusting the atomic ratio (at%) of niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) compared to the precious metal precursor and by annealing.

[0154] When the size of the nanocluster (S2) is formed to be 5 nm or less, the mass activity, which means the current according to the amount of catalyst (123), can be effectively increased, as shown in Fig. 7.

[0155] Figure 7 shows the 600 mM chloride ion (Cl) of the catalyst layer provided in the catalyst electrode of the present embodiment. - ) is a graph showing electrochemical chlorine generation activity data at the catalyst electrode according to the form of single atoms and nanoclusters under concentration conditions and a graph showing mass activity.

[0156] Referring to Fig. 7, the metal and metal oxide catalysts in the form of a single atom exhibited a current density of about 30 mA / mgM (M=Ir or Pt) at 1.5 V vs NHE (normal hydrogen electrode). It has a mass activity of chlorine generation reaction, which is more than 8 times that of nano clusters having a mass activity of about 0.50-3.50 mA / mgM (M= Ir or Pt).

[0157] The above niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) may each have an anatase structure.

[0158] Titanium oxide nanoparticles can have three structures: anatase, rutile, and brookite. The anatase structure has superior photocatalytic activity in photodecomposing pollutants in water or air compared to the rutile and brookite structures, and thus can increase catalytic activity.

[0159] The conductive carrier (121) on which the above catalyst (123) is supported is M a Nb b Ti c It can have a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

[0160] When the conductive support on which the catalyst is supported is formed to have the above composition, a high chlorine generation efficiency can be obtained even with a small amount of precious metal.

[0161] According to this configuration, the adhesion between the catalyst layer (120) and the titanium substrate (110) is improved, so the durability of the catalyst electrode is increased even without forming a separate protective layer to protect the catalyst layer (120).

[0162] Figure 8 shows 600 mM chloride ion (Cl - ) is a graph showing the ECSA (electrically active surface area) measurement data of the catalyst layer provided in the catalyst electrode of the present embodiment under an electrolyte having a concentration of 0.1 M and a graph showing the double layer capacitance.

[0163] Here, “double layer capacitance” represents the active area of ​​the catalyst.

[0164] Referring to FIG. 8, it can be seen that the metal and metal oxide catalysts in the form of a single atom have a capacitance per unit metal mass of about 300 F / gM (M=Ir or Pt), which is more than three times the capacitance per unit metal mass of about 10 to 70 F / gM (M=Ir or Pt).

[0165] That is, it can be seen that the metal and metal oxide catalysts in the form of a single atom have a capacitance per unit mass of the noble metal that is three times greater than that per unit mass of the noble metal.

[0166] Figure 9 shows a chloride ion (Cl) of less than 1 mM - ) is a graph showing the electrochemical chlorine generation selectivity data at the electrode according to the single-atom and nano-cluster forms of the catalyst layer provided in the catalyst electrode of the present embodiment under concentration conditions.

[0167] Referring to Figure 9, it can be seen that the metal and metal oxide catalysts in the form of single atoms show a faradaic efficiency of 0.75% or more than the metal and metal oxide catalysts in the form of nano clusters. (Current density: 60 mA / cm 2 )

[0168] A method for manufacturing an electrochemically insoluble catalyst electrode of this configuration is described with reference to FIG. 2.

[0169] Figure 2 is a block diagram schematically showing a method for manufacturing an electrochemically insoluble catalyst electrode according to the present specification.

[0170] The manufacturing method of the present embodiment comprises: a step of treating the surface of a support substrate (110) (S110); a step of preparing a conductive support (121) including niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) (S120); a step of preparing a support solution including one transition metal precursor selected from among iridium (Ir) and platinum (Pt) (S130); a step of preparing a coating solution by supporting the niobium-doped titanium oxide (Nb:TiO2) nanoparticles (1221) in the support solution (S140); a step of coating the support substrate (110) with the coating solution to form a coating layer (S150); And the step (S160) of forming a catalyst layer (120) in which a transition metal or transition metal oxide made of iridium or platinum is supported on the conductive support (121) as a catalyst (123) in the form of a single atom or cluster by firing the coating layer may be included.

[0171] The above support substrate (110) may be made of a titanium substrate, and the step (S110) of treating the surface of the support substrate may include a step of sandblasting the surface of the support substrate (110) to form a surface roughness of the support substrate of 1 µm to 5 µm; and a step of etching the surface of the support substrate (110) at room temperature with 0.1 M to 1.0 M sulfuric acid.

[0172] According to this configuration, since the conductive carrier (121) is formed of titanium oxide, which is the same material as the titanium substrate (110), the thermal expansion coefficients of the surface of the titanium substrate (110) and the catalyst layer (120) are formed to be similar.

[0173] Accordingly, since the adhesion between the catalyst layer (120) and the titanium substrate (110) is improved, the durability of the catalyst electrode (100) is increased even without forming a separate protective layer to protect the catalyst layer (120).

[0174] And, by performing an etching step using sulfuric acid, alumina particles remaining on the surface of the titanium substrate after being used in sandblasting treatment can be effectively removed.

[0175] The above niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) can be manufactured using a hydrothermal synthesis method.

[0176] Using a hydrothermal synthesis method, the niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) can be formed with a size of 4 nm to 40 nm, and can be formed with an anatase structure.

[0177] Nanoparticles having the above size can effectively perform the role of a support while securing the maximum specific surface area on which the catalyst (123) can be supported.

[0178] In addition, the anatase structure has excellent photocatalytic activity in photodecomposing pollutants present in water or air compared to the rutile structure and brookite structure, so the catalytic activity can be increased.

[0179] When manufacturing a conductive support using a hydrothermal synthesis method, titanium isopropoxide or titanium butoxide can be used as a titanium precursor, niobium(V) chloride or niobium ethoxide can be used as a niobium precursor, and a solution containing an organic solvent including either ethanol or isopropyl alcohol (2-propanol) and water in a ratio of 1:1 to 4:1 can be used as a synthesis solution.

[0180] And the pH of the above synthetic solution can be formed in the range of 0 to 2.

[0181] The amount of niobium (Nb) doped into titanium oxide nanoparticles (121) may vary depending on the ratio of the titanium precursor and the niobium precursor.

[0182] And the size of niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) may vary depending on the type and pH of the synthesis solution.

[0183] In the step of preparing a support solution (S130), the support solution can be prepared by mixing an organic solvent including one of ethanol and isopropyl alcohol (2-propanol) and water in a range of 50:50 to 100:0.

[0184] And the pH of the above-mentioned solution can be formed in the range of 2 to 5.

[0185] The amount of noble metal precursor loaded on niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) may vary depending on the type and pH of the loading solution.

[0186] The conductive carrier (121) on which the above catalyst (123) is supported is M a Nb b Tic It can have a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

[0187] By controlling the atomic ratio (at%) of niobium-doped titanium oxide (Nb:TiO2) nanoparticles (121) compared to a precious metal precursor and through an annealing process, the size of the metal and metal oxide catalyst supported on the surface of the niobium-doped titanium oxide (Nb:TiO2) nanoparticles can be controlled, and clusters can be formed with a size of 5 nm or less.

[0188] By forming the cluster size to be less than 5 nm, the mass activity, which means the current according to the amount of catalyst, can be effectively increased.

[0189] The step (S160) of forming the above catalyst layer (120) may include a two-step annealing step.

[0190] For example, the step (160) of forming the catalyst layer may include a first annealing step of annealing the coating layer at a temperature of 200°C to 300°C, a cleaning step of cleaning the coating layer using dimethyl sulfoxide or distilled water, and a second annealing step of annealing the coating layer at a temperature of 450°C to 500°C.

[0191] Figure 10 is a HAADF-STEM image of a catalyst layer manufactured through two-step annealing of the present embodiment.

[0192] Figure 11 shows the results of a catalyst layer manufactured through only one annealing and a catalyst layer manufactured through two-step annealing of the present embodiment with 600 mM chloride ion (Cl - ) is a linear sweep voltammetry graph showing the electrochemical chlorine generation reaction activity under concentration conditions.

[0193] Figure 12 shows the chloride ion (Cl) content of 1 mM or less in a catalyst layer manufactured through only one annealing and a catalyst layer manufactured through two-step annealing of the present embodiment. - ) is a graph showing the electrochemical chlorine generation selectivity data under concentration conditions.

[0194] Referring to FIGS. 10 to 12, the monoatomic metal and metal oxide catalysts made through two annealing processes, i.e., two-step annealing, have a 10 mA / cm higher conductivity than the monoatomic metal and metal oxide catalysts made through only one annealing process. 2 It exhibits an overvoltage as low as 13 mV at a current density of .

[0195] And the single-atom catalyst in the form of metal and metal oxide made through only one annealing and the single-atom catalyst in the form of metal and metal oxide made through two-step annealing have less than 1 mM chloride ion (Cl - ) When comparing the faradaic efficiency values ​​under ultra-low salt conditions with a concentration of 0.38%, the monoatomic metal and metal oxide catalysts produced through two-step annealing show a faradaic efficiency of 0.38% or more compared to the monoatomic metal and metal oxide catalysts produced through only one annealing.

[0196] According to this configuration, the electrolyte (Cl - ) can be manufactured to increase the efficiency of the chlorine generation reaction in extremely low-salinity tap water containing a small amount of chlorine, for example, tap water having a Cl concentration of 5 ppm to 50 ppm.

[0197] And since the catalyst layer can be formed with a porous structure having a plurality of pores having a size of several tens of nm to several μm, the catalyst surface area of ​​the catalyst electrode can be increased due to the porous network of niobium oxide, which is a conductive oxide.

[0198] And, since the porous network can support a metal or metal oxide catalyst of single-atom or sub-nanometer size, it is possible to manufacture an electrochemically insoluble catalyst electrode having a catalytic activity comparable to that of a conventional precious metal-based catalyst, while having a very low total precious metal content of 5% or less, thereby reducing the manufacturing cost.

[0199] In addition, the single-atom or sub-nanometer sized iridium (Ir) or platinum (Pt)-based catalysts included in the present specification have high atomic utilization efficiency compared to bulk catalysts, so that high chlorine generation efficiency can be obtained even with a small amount of metal.

[0200] In addition, the electrode structure presented in this specification can achieve high chlorine generation efficiency under extremely low salinity conditions such as tap water by controlling the overall morphology of the electrode as well as by simply changing the composition of the catalyst.

[0201] It will be apparent to those skilled in the art that this specification may be embodied in other specific forms without departing from the essential characteristics thereof. Therefore, the foregoing detailed description should not be construed in any way as limiting but rather as illustrative. The scope of this specification should be determined by a reasonable interpretation of the appended claims, and all changes within the scope of equivalents herein are intended to be included within the scope of this specification.

Claims

1. Supporting substrate; and A catalyst layer positioned on the above support substrate Including, The above catalyst layer, A conductive support comprising niobium-doped titanium oxide nanoparticles; and A catalyst formed by supporting a transition metal or transition metal oxide on the conductive support in the form of a single atom or cluster. Includes, An electrochemically insoluble catalyst electrode comprising the above transition metal or the above transition metal oxide selected from among iridium (Ir) and platinum (Pt).

2. In paragraph 1, The above niobium-doped titanium oxide nanoparticles each have a size of 4 nm to 40 nm, and are an electrochemically insoluble catalyst electrode.

3. In paragraph 1, The above cluster is an electrochemically insoluble catalyst electrode having a size of 5 nm or less.

4. In paragraph 1, The above niobium-doped titanium oxide nanoparticles are electrochemically insoluble catalyst electrodes each having an anatase structure.

5. In paragraph 1, An electrochemically insoluble catalyst electrode in which the catalyst layer is formed into a porous structure having a plurality of pores having a size of several tens of nm to several μm.

6. In any one of paragraphs 1 to 5, The conductive support on which the catalyst is supported is M a Nb b Ti c An electrochemically insoluble catalyst electrode having a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

7. In paragraph 6, The above support substrate is an electrochemically insoluble catalyst electrode formed of titanium.

8. Step of treating the surface of the supporting substrate; A step of manufacturing a conductive support comprising niobium-doped titanium oxide nanoparticles; A step of preparing a supporting solution containing a transition metal precursor selected from among iridium (Ir) and platinum (Pt); A step of preparing a coating solution by supporting the niobium-doped titanium oxide nanoparticles in the supporting solution; A step of forming a coating layer by coating the above coating solution on the above supporting substrate; and A step of firing the coating layer to form a catalyst layer in which a transition metal or transition metal oxide made of iridium or platinum is supported on the conductive support as a catalyst in the form of a single atom or cluster. A method for manufacturing an electrochemically insoluble catalyst electrode comprising:

9. In paragraph 8, The step of treating the surface of the above support substrate is: A step of sandblasting the surface of the support substrate to form the surface roughness of the support substrate to 1 µm to 5 µm; and A step of etching the surface of the support substrate at room temperature with 0.1 M to 1.0 M sulfuric acid. A method for manufacturing an electrochemically insoluble catalyst electrode comprising:

10. In paragraph 8, A method for producing an electrochemical insoluble catalyst electrode by using a hydrothermal synthesis method to produce niobium-doped titanium oxide nanoparticles.

11. In paragraph 10, A method for manufacturing an electrochemically insoluble catalyst electrode, wherein the niobium-doped titanium oxide nanoparticles are each formed to have a size of 4 nm to 40 nm.

12. In paragraph 10, A method for manufacturing an electrochemically insoluble catalyst electrode in which the niobium-doped titanium oxide nanoparticles are each formed into an anatase structure.

13. In paragraph 10, Titanium isopropoxide or titanium butoxide is used as a titanium precursor. Niobium(V) chloride or niobium(V) ethoxide is used as a niobium precursor. A method for manufacturing an electrochemically insoluble catalyst electrode using a solution in which an organic solvent containing either ethanol or isopropyl alcohol (2-propanol) and water are mixed in a ratio of 1:1 to 4:1 as a synthetic solution.

14. In paragraph 13, A method for producing an electrochemically insoluble catalyst electrode, wherein the pH of the above synthetic solution is formed in the range of 0 to 2.

15. In paragraph 8, A method for producing an electrochemically insoluble catalyst electrode, wherein the above-mentioned supporting solution is prepared by mixing an organic solvent containing one of ethanol and isopropyl alcohol (2-propanol) and water in a range of 50:50 to 100:

0.

16. In paragraph 15, A method for manufacturing an electrochemically insoluble catalyst electrode, wherein the pH of the above-mentioned supporting solution is formed in the range of 2 to 5.

17. In any one of paragraphs 8 to 16, The conductive support on which the catalyst is supported is M a Nb b Ti c A method for manufacturing an electrochemically insoluble catalyst electrode having a composition formula of O2(0≤ a ≤ 0.05, 0 ≤ b ≤ 0.10, 0.95 ≤ b+c ≤ 1.00, M = Ir or Pt).

18. In paragraph 17, The step of forming the above catalyst layer is: A first annealing step of annealing the coating layer at a temperature of 200°C to 300°C; A cleaning step of cleaning the coating layer using dimethyl sulfoxide or distilled water, and A second annealing step of annealing the coating layer at a temperature of 450°C to 500°C. A method for manufacturing an electrochemically insoluble catalyst electrode comprising:

19. In paragraph 18, A method for manufacturing an electrochemically insoluble catalyst electrode that forms clusters having a size of 5 nm or less.

20. In paragraph 18, An electrochemically insoluble catalyst electrode having a porous structure having a plurality of pores having a size of several tens of nm to several μm, and forming the catalyst layer.

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