Electrochemically treated silver nanocluster catalyst for carbon dioxide conversion, manufacturing method thereof, gas diffusion electrode including same, zero-gap reactor including same, and carbon dioxide conversion method using same

Abstract

The present invention relates to an electrochemically treated silver nanocluster catalyst for carbon dioxide conversion, a gas diffusion electrode comprising the same, a zero-gap reactor comprising the same, and a method for converting carbon dioxide using the same that exhibits excellent conversion rate and high selectivity.

Description

Technology Field

[0001] The present invention relates to an electrochemically treated silver nanocluster catalyst for carbon dioxide conversion, a method for manufacturing the same, a gas diffusion electrode comprising the same, a zero-gap reactor comprising the same, and a method for converting carbon dioxide using the same. Background Technology

[0002] Nanoclusters are more stable than single atoms or nanoparticles, and because their molecular properties are stronger than their metallic properties, they possess optical and electrochemical properties entirely different from those of nanoparticles. In particular, as the optical, electrical, and catalytic properties of nanoclusters vary sensitively depending on the number and type of metal atoms and ligands, research on nanoclusters is currently underway in a wide variety of fields.

[0003] Meanwhile, due to the recent global climate crisis, research on carbon dioxide conversion technologies, a greenhouse gas, is actively underway. Among these, carbon dioxide conversion technology via electrochemical reduction is a technique that reduces carbon dioxide into useful carbon compounds by inputting electrical energy to generate a potential difference between electrodes and inducing electron movement. This technology has the advantages of being able to perform the carbon dioxide reduction reaction even under ambient temperature and pressure conditions, requiring only water and carbon dioxide as raw materials, thereby preventing the emission of chemical substances through the recycling of electrolytes, and furthermore, featuring a simple process.

[0004] Furthermore, regarding carbon dioxide electrochemical reduction technology, conventionally, flow electrolytic cells with a gap structure in which the electrode and the separator are separated by a distance of several millimeters were used. However, recently, research is gaining attention on utilizing zero-gap reactors with a sandwich-type structure in which the anode and cathode are in contact with a separator, thereby eliminating the gap between the electrode and the separator to reduce ionic resistance within the gap and mitigate the increase in mass transfer resistance caused by generated gases when implementing large-area electrodes.

[0005] Since such electrochemical reduction technologies are significantly affected by reaction conditions such as the type of electrode catalyst, electrolyte properties, pH, temperature, and pressure, research on the type of electrode catalyst and the electrolyte used is particularly necessary to reduce carbon dioxide and convert it into useful carbon compounds.

[0006] Currently, gold catalysts are primarily used as electrode catalysts, but due to their high cost and limited reserves, there is a need to develop other metal catalysts with excellent carbon dioxide conversion activity. Prior art literature

[0007] Korean Registered Patent KR 10-2372659 B1 The problem to be solved

[0008] The objective of the present invention is to provide a silver nanocluster catalyst with excellent carbon dioxide conversion performance, a gas diffusion electrode including the same, and a zero-gap reactor including the same.

[0009] Another objective of the present invention is to provide a method for converting carbon dioxide using the zero-gap reactor to exhibit excellent conversion performance and excellent selectivity.

[0010] In addition, the present invention provides a method for manufacturing a silver nanocluster catalyst for carbon dioxide conversion with significantly improved catalytic activity by including a step of electrochemical treatment. means of solving the problem

[0011] The present invention provides a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1.

[0012] [Chemical Formula 1]

[0013] XAg 14 (R 1 ) n

[0014] [In the above chemical formula 1,

[0015] R 1C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0016] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, or C6-C20 arylalkyl; X is a halogen; and n is an integer from 6 to 11.

[0017] R of the above chemical formula 1 1 C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, C3-C10 cycloalkyl, C5-C10 heteroaryl, C3-C10 heterocycloalkyl, C6-C10 arylalkyl, or SR 11 is; R 11 is a C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, C3-C10 cycloalkyl, C5-C10 heteroaryl, C3-C10 heterocycloalkyl or C6-C10 arylalkyl; X is a halogen; and n may be an integer from 6 to 11.

[0018] In addition, R of Formula 1 according to one embodiment of the present invention 1 It is C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, or SR 11 is; R 11 is a C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl or C6-C10 arylalkyl; X is a halogen; and n can be an integer from 6 to 11.

[0019] R of Formula 1 according to one embodiment of the present invention 1 is a C1-C10 alkyl, C2-C10 alkenyl, or C3-C10 alkynyl; X is a halogen; and n can be an integer from 7 to 10.

[0020] The present invention provides a gas diffusion electrode for carbon dioxide conversion, which may include a porous support and a silver nanocluster catalyst according to one embodiment of the present invention fixed in the pores of the porous support, wherein the porous support may be a carbon body and the average pore size of the porous support may be 10 to 1000 nm.

[0021] In one embodiment of the present invention, the average particle size of the silver nanoclusters used in the gas diffusion electrode for carbon dioxide conversion may be 1 to 5 nm, and the silver nanocluster catalyst may have a density of 1 to 100 nmol / cm² per unit area of ​​the porous support. 2 It may be loaded at a density of

[0022] The present invention provides a zero-gap reactor for carbon dioxide conversion, wherein the zero-gap reactor may comprise an anode; a cathode comprising a silver nanocluster according to one embodiment; and a separator located between the cathode and the anode.

[0023] The above cathode may be disposed in contact with one surface of the separator, the above anode may be one or more selected from nickel, iron, and iridium, and the separator may be an ion exchange membrane.

[0024] The present invention provides a carbon dioxide conversion method, wherein the method may include the step of supplying carbon dioxide to one side of a cathode of a zero-gap reactor for carbon dioxide conversion according to one embodiment; and the step of obtaining carbon monoxide converted from carbon dioxide from one side of the cathode.

[0025] A method for preparing a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1 according to one embodiment of the present invention may include the step of mixing a silver precursor, a ligand compound, an alkylammonium halide, and a reducing agent; and the step of electrochemically treating the mixture.

[0026] [Chemical Formula 1]

[0027] XAg 14 (R 1 ) n

[0028] [In the above chemical formula 1,

[0029] R 1 C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0030] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, or C6-C20 arylalkyl; X is a halogen; and n is an integer from 6 to 11.

[0031] The above ligand compound may be a C3-C20 alkynyl compound, the molar ratio of the silver precursor to the alkylammonium halide may be 1:0.01 to 0.5, and the silver precursor may be one or more selected from AgNO3, AgBF4, AgCF3SO3, AgClO4, AgO2CCH3, and AgPF6.

[0032] A method for preparing a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1 according to one embodiment of the present invention may include the step of mixing a silver precursor, a ligand compound, and a halide compound in an aqueous solution; and the step of electrochemically treating the mixture.

[0033] [Chemical Formula 1]

[0034] XAg 14 (R 1 ) n

[0035] [In the above chemical formula 1,

[0036] R 1C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0037] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, or C6-C20 arylalkyl; X is a halogen; and n is an integer from 6 to 11.

[0038] The above ligand compound may be a C3-C20 alkynyl compound, and the above halide compound may be an alkali metal salt. Effects of the invention

[0039] The silver nanoclusters of the present invention have structural stability consisting of atoms and ligands within a specific number range, and exhibit excellent activity for the conversion reaction of carbon dioxide compared to conventional silver-based catalysts.

[0040] The silver nanocluster catalyst of the present invention is inexpensive and has excellent uniformity, making it very useful as a catalyst for the conversion of carbon dioxide.

[0041] The gas diffusion electrode containing silver nanoclusters and the zero-gap reactor containing the same according to the present invention exhibit superior performance compared to the conversion of carbon dioxide using conventional flow electrolyzers, and is a system with greatly improved selectivity for the conversion reaction of carbon dioxide.

[0042] Therefore, by using the gas diffusion electrode for carbon dioxide conversion reaction of the present invention and the zero-gap reactor including the same, carbon dioxide can be effectively converted with high selectivity and conversion rate.

[0043] In addition, the method for manufacturing the silver nanocluster catalyst for carbon dioxide conversion according to the present invention has very high industrial utility value because it not only significantly improves catalytic activity by exposing the active sites of the catalyst through an electrochemical treatment step, but also enables mass production with high yield through a simple process. Brief explanation of the drawing

[0044] Figure 1 is a schematic diagram showing a zero-gap reactor including a gas diffusion electrode for carbon dioxide conversion. FIG. 2 is a schematic diagram showing the electrochemical treatment step in the method for manufacturing silver nanoclusters for carbon dioxide conversion according to the present invention. Figure 3 is a figure showing the results of the ESI-MS of Preparation Example 1. Figure 4 is a figure showing the UV-Vis results of Preparation Example 1 and Preparation Example 2. Figure 5 is a figure showing the EXAFS results of Preparation Example 1 and Preparation Example 2. Figure 6 is a figure showing the UV-Vis results of Preparation Examples 5 to 7. Figure 7 is a figure showing the carbon dioxide conversion activity results of Example 1 and Comparative Example 1. Figure 8 is a figure showing the carbon dioxide conversion activity results of Example 1 and Comparative Example 1. Figure 9 is a figure showing the electrochemical activity results of Example 1 and Comparative Example 1. Figure 10 is a figure showing the electrochemical activity results of Example 1 and Comparative Example 1. Figure 11 is a figure showing the electrochemical activity results of Examples 2 to 4. Specific details for implementing the invention

[0045] Hereinafter, the electrochemically treated silver nanocluster catalyst for carbon dioxide conversion according to the present invention, a method for manufacturing the same, a gas diffusion electrode including the same, a zero-gap reactor including the same, and a method for converting carbon dioxide using the same will be described in detail.

[0046] The singular form used in the present invention may be intended to include the plural form unless specifically indicated in the context.

[0047] Furthermore, the numerical range used in the present invention includes lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of the specified values, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0048] In the description of the present invention, "comprising" is an open description having an equivalent meaning to expressions such as "comprising," "containing," "having," or "characterizing," and does not exclude elements, materials, or processes not additionally listed.

[0049] The “alkyl” described in the present invention refers to a straight-chain or branched non-cyclic hydrocarbon and may have 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. In another embodiment, the alkyl may have 1 to 3 carbon atoms.

[0050] The term "alkenyl" as used in the present invention refers to a saturated straight-chain or branched non-cyclic hydrocarbon comprising at least one carbon-carbon double bond, and includes, but is not limited to, -vinyl, -allyl, -1-butenyl, -2-butenyl, -isobutylenyl, -1-pentenyl, -2-pentenyl, -3-methyl-1-butenyl, -2-methyl-2-butenic, -2,3-dimethyl-2-butenyl, -1-hexenyl, -2-hexenyl, -3-hexenyl, -1-heptenyl, -2-heptenyl, -3-heptenyl, -1-octenyl, -2-octenyl, -3-octenyl, -1-nonenyl, -2-nonenyl, -3-nonenyl, -1-disenyl, -2-disenyl, and -3-disenyl. These alkenyl groups can be optionally substituted. The alkenyl includes radicals having cis and trans orientations, or alternatively, E and Z orientations.

[0051] The term "alkynyl" as used in the present invention refers to a saturated straight-chain or branched non-cyclic hydrocarbon having at least one carbon-carbon triple bond, and includes, but is not limited to, an ethynyl group, a propynyl group, a butynyl group, a butadiinyl group, a pentynyl group, a pentadiinyl group, a hexinyl group, a hexadiinyl group, and isomers thereof.

[0052] The “cycloalkyl” described in the present invention refers to a monocyclic or polycyclic saturated ring comprising carbon and hydrogen atoms and not having carbon-carbon multiple bonds. It includes, but is not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. The cycloalkyl group may be optionally substituted. Furthermore, the cycloalkyl group includes one or more heteroatoms selected from B, O, N, C(=O), P, P(=O), S, S(=O)2, and Si atoms.

[0053] The term "halogen" as used in the present invention means fluorine, chlorine, bromine, or iodine.

[0054] The term “aryl” as described in the present invention refers to a carbon-ring aromatic group containing 5 to 20 ring atoms. Representative examples include, but are not limited to, phenyl, tolyl, xylyl, naphthyl, tetrahydronaphthyl, anthracenyl, fluorenyl, indenyl, and azulenyl. Furthermore, the aryl includes a carbon-ring aromatic group connected to an alkylene or alkenylene group, or connected to one or more heteroatoms selected from B, O, N, C(=O), P, P(=O), S, S(=O)2, and Si atoms.

[0055] The carbon number described in the present invention does not include the carbon number of the substituent, for example, C1-C10 alkyl means an alkyl having 1 to 10 carbons that does not include the carbon number of the alkyl substituent.

[0056] The present invention will be described in detail below. Unless otherwise defined, technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which this invention pertains, and descriptions of known functions and configurations that could unnecessarily obscure the essence of the invention are omitted in the following description.

[0057] The carbon dioxide conversion technology through electrochemical reduction proceeds as shown in Reaction Scheme 1 below, and the carbon dioxide reduction reaction takes place in an aqueous electrolyte. Since the reduction potential ranges of hydrogen generated from the aqueous solution and carbon dioxide are similar, the carbon dioxide reduction reaction and hydrogen generation can occur simultaneously, making selectivity a very important issue.

[0058] [Reaction Equation 1]

[0059] CO2+ e - + H2O → COOH* + OH - 120mVdec -1

[0060] COOH* + e - → CO* + OH - 40mVdec -1

[0061] CO* → CO 30mVdec -1

[0062] As a result of further research on this, the inventors discovered that the silver nanocluster of the present invention is inexpensive, has excellent uniformity, and is highly selective for carbon dioxide reduction, and that the catalytic activity is significantly enhanced by exposing the active site through the electrochemical treatment step in which the ligand is detached.

[0063] The present invention provides a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1.

[0064] [Chemical Formula 1]

[0065] XAg 14 (R 1 ) n

[0066] [In the above chemical formula 1,

[0067] R 1 C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0068] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl or C6-C20 arylalkyl;

[0069] X is a halogen;

[0070] n is an integer from 6 to 11.

[0071] The silver nanocluster of the present invention has a structure composed of atoms and ligands within a specific number range, and not only has excellent activity for the conversion reaction of carbon dioxide, but also has excellent stability compared to conventional gold (Au)-based catalysts, and is very useful as a catalyst for the conversion of carbon dioxide because it is inexpensive and has excellent uniformity.

[0072] R of the above chemical formula 1 1 C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, C3-C10 cycloalkyl, C5-C10 heteroaryl, C3-C10 heterocycloalkyl, C6-C10 arylalkyl, or SR 11 is; R 11 is a C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, C3-C10 cycloalkyl, C5-C10 heteroaryl, C3-C10 heterocycloalkyl or C6-C10 arylalkyl; X is a halogen; and n may be an integer from 6 to 11.

[0073] In addition, R of Formula 1 according to one embodiment of the present invention 1 It is C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, or SR 11 is; R 11 is a C1-C10 alkyl, C2-C10 alkenyl, C3-C10 alkynyl, C6-C10 aryl, or C6-C10 arylalkyl; X is a halogen; and n may be an integer from 6 to 11, and in detail R of Formula 1. 1 is a C1-C10 alkyl, C2-C10 alkenyl, or C3-C10 alkynyl; X is a halogen; and n can be an integer from 7 to 10.

[0074] The present invention provides a gas diffusion electrode for carbon dioxide conversion, which may include a porous support and a silver nanocluster catalyst according to one embodiment of the present invention fixed in the pores of the porous support.

[0075] The above-mentioned porous support can be used as a microporous layer (MPL) and is not limited to any other porous support having conductivity, and specifically, it may be a carbon material. Specific examples of the carbon material may be one or more selected from carbon black, carbon nanotubes, graphene, carbon nanofibers, and graphitized carbon black, and more specifically, it may be carbon black, but are not limited thereto.

[0076] In addition, the average pore size of the porous support may be 10 to 1000 nm, specifically 10 to 500 nm, more specifically 10 to 100 nm, but is not limited thereto.

[0077] In one embodiment of the present invention, the average particle size of the silver nanoclusters used in the gas diffusion electrode for carbon dioxide conversion may be 1 to 5 nm, and the silver nanocluster catalyst may have a density of 1 to 100 nmol / cm² per unit area of ​​the porous support. 2 It may be supported at a density of , preferably 1 to 50 nmol / cm² 2 , more preferably 1 to 30 nmol / cm² 2 It may be loaded at a density of

[0078] A method for supporting metal nanoclusters on a porous support according to one embodiment may be a method of preparing a solution in which metal nanoclusters are dispersed on the porous support, dropping it onto the support, drying it, and then heat treating it. The above method allows the metal nanocluster dispersion to be easily applied to the entire surface of the support by capillary action simply by dropping it onto the porous support, and is a method that results in uniform coating and stable support. Any organic solvent that is possible within the range recognized by a person skilled in the art in this technical field may be used as the solvent. Specifically, it may be one or more selected from ethanol, methanol, isopropanol, butanol, pentanol, hexanol, dichloromethane, hexane, acetone, ethylene glycol, diethylene glycol, glycerol, and propylene glycol, but is not limited thereto.

[0079] As metal nanoclusters are included as the catalytic compound of the above cathode, they can be dispersed and adsorbed at a molecular level within the pores of a porous support compared to conventional metal nanoparticle catalysts. Accordingly, a cathode containing metal nanoclusters can have significantly superior electrochemical carbon dioxide conversion characteristics compared to a cathode containing a metal nanoparticle catalyst.

[0080] In addition, in one embodiment of the present invention, the cathode may reduce carbon dioxide to carbon monoxide. More specifically, the zero-gap reactor of the present invention is as shown in the schematic diagram of FIG. 1, and carbon dioxide supplied to the cathode is converted into carbon monoxide and released. The electrolyte of the zero-gap reactor may be KCl, NaOH, or an aqueous solution of KOH; specifically, the electrolyte may have a pH of 7 to 14, and more specifically, a pH of 8 to 14. The concentration of the aqueous solution may be 0.1 to 10 M, more specifically 0.5 to 5 M, and more specifically 0.5 to 3 M, but is not limited thereto.

[0081] The present invention provides a zero-gap reactor for carbon dioxide conversion, wherein the zero-gap reactor may comprise an anode; a cathode comprising a silver nanocluster according to one embodiment; and a separator located between the cathode and the anode.

[0082] The gas diffusion electrode containing silver nanoclusters and the zero-gap reactor containing the same according to the present invention exhibit superior performance compared to the conversion of carbon dioxide using conventional flow electrolyzers, and is a system with greatly improved selectivity for the conversion reaction of carbon dioxide.

[0083] The separator may be positioned in a sandwich form between the cathode and the anode, and the cathode may be positioned in contact with one side of the separator. Specifically, the separator may be positioned in contact with the microporous layer (MPL) of a gas diffusion electrode containing silver nanoclusters, which is the cathode.

[0084] The above anode is a conductive metal, specifically one or more selected from nickel, iron, and iridium. More specifically, the anode may be a conductive metal foam, for example, a porous nickel foam (Ni foam), but is not limited thereto.

[0085] The above-mentioned membrane must be durable in a strong basic environment, and a material having low gas permeability and high ion conductivity may be used; in one embodiment, the membrane may be an ion exchange membrane. Such an ion exchange membrane may be manufactured from ion exchange resins and ionomers known in the art, or may be purchased and used as a film. For example, Nafion™ series membranes containing perfluorosulfonic acid groups from DuPont, USA, may be used, and commercial membranes of a similar type such as Solvey’s Aquivion PFSA membrane, Fumatek’s Fumasep ion exchange membrane including cation and anion exchange membranes, Dioxide Materials’ anion exchange membrane, Orion polymer’s anion exchange membrane, Asahi Chemicals’ Aciplex-S membrane, Dow Chemicals’ Dow membrane, Asahi Glass’s Flemion membrane, and Gore & Associate’s GoreSelcet membrane may be used, but are not limited thereto.

[0086] The present invention provides a method for converting carbon dioxide, wherein the method may include the step of supplying carbon dioxide to one side of a cathode of a zero-gap reactor for converting carbon dioxide according to one embodiment of the present invention; and the step of obtaining carbon monoxide converted from carbon dioxide from one side of the cathode.

[0087] By using the gas diffusion electrode for carbon dioxide conversion reaction of the present invention and the zero-gap reactor including the same, carbon dioxide can be effectively converted with high selectivity and conversion rate.

[0088] A method for preparing a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1 according to one embodiment of the present invention may include the step of mixing a silver precursor, a ligand compound, an alkylammonium halide, and a reducing agent; and the step of electrochemically treating the mixture.

[0089] [Chemical Formula 1]

[0090] XAg 14 (R 1 ) n

[0091] [In the above chemical formula 1,

[0092] R 1 C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0093] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl or C6-C20 arylalkyl;

[0094] X is a halogen;

[0095] n is an integer from 6 to 11.

[0096] Specifically, the ligand compound may be a C3-C20 alkynyl compound, a C3-C10 alkynyl compound, or a C3-C7 alkynyl compound. The molar ratio of the silver precursor to the ligand compound may be 1:0.1 to 10, preferably 1:0.2 to 7, and more preferably 1:0.5 to 5. This range is desirable as it allows for excellent synthesis efficiency while reducing reaction impurities.

[0097] In a method for preparing a catalyst according to one embodiment, the molar ratio of silver precursor to reducing agent may be 1:0.1 to 10, preferably 1:0.2 to 7, and more preferably 1:0.5 to 5, but is not limited thereto.

[0098] In addition, the molar ratio of the silver precursor to the alkylammonium halide may be 1:0.01 to 0.5, preferably 1:0.02 to 0.3, and more preferably 1:0.03 to 0.2.

[0099] In one embodiment, the silver precursor may be one or more selected from AgNO3, AgBF4, AgCF3SO3, AgClO4, AgO2CCH3, and AgPF6, specifically one or more selected from AgNO3, AgBF4, and AgPF6, and more specifically AgNO3 or AgBF4, but is not limited thereto.

[0100] In one embodiment, the manufacturing method may further include a solvent, and the solvent may be used without particular limitation as long as it is commonly used in the art. As a specific example, it may be one or more mixed solvents selected from C1-C5 alcohols, acetonitrile, dimethyl sulfoxide, dimethylformamide, acetone, tetrahydrofuran, and 1,4-adioxane, and preferably tetrahydrofuran, but is not limited thereto.

[0101] In addition, the method for preparing the silver nanocluster according to one embodiment may further include a step of precipitating and separating with a nonpolar solvent, and the nonpolar solvent used therein may be one or more selected from n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cis-cyclooctene, toluene, m-, o-, p-xylene, t-butylmethyl ether, and di-n-butyl ether, specifically one or more selected from n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and cis-cyclooctene, and more specifically one or more selected from n-pentane, n-hexane, and n-heptane, but is not limited thereto.

[0102] The above alkylammonium halide may be a C10-C30 alkylammonium halide, preferably a C12-C20 alkylammonium halide, and more preferably a C14-C18 alkylammonium halide.

[0103] The above reducing agent may be one or more selected from triethylamine, oleylamine, carbon monoxide, and sodium borohydride, and specifically may be triethylamine, but is not limited thereto.

[0104] In a method for preparing a catalyst according to one embodiment, the step of electrochemically treating the mixture may include: a step of dispersing a mixture obtained by mixing a silver precursor, a ligand compound, an alkylammonium halide, and a reducing agent onto a working electrode; a step of preparing another counter electrode and a reference electrode; and a step of applying a potential of -3.0 to -0.01 V to the working electrode. Specifically, the reference electrode may be Ag / AgCl, and the counter electrode may include nickel, but is not limited thereto.

[0105] In one embodiment, the working electrode may be a porous electrode, and more specifically, may be a porous electrode based on any one metal selected from the group consisting of carbon, nickel, and silver, but is not limited thereto.

[0106] In addition, the step of applying the above potential may be performed for 1 minute to 10 hours, and preferably for 30 minutes to 3 hours.

[0107] A method for preparing a silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1 according to one embodiment of the present invention may include the step of mixing a silver precursor, a ligand compound, and a halide compound in an aqueous solution; and the step of electrochemically treating the mixture.

[0108] [Chemical Formula 1]

[0109] XAg 14 (R 1 ) n

[0110] [In the above chemical formula 1,

[0111] R 1 C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl, C6-C20 arylalkyl or SR 11 is;

[0112] R 11 is a C1-C20 alkyl, C2-C20 alkenyl, C3-C20 alkynyl, C6-C20 aryl, C3-C20 cycloalkyl, C5-C20 heteroaryl, C3-C20 heterocycloalkyl or C6-C20 arylalkyl;

[0113] X is a halogen;

[0114] n is an integer from 6 to 11.

[0115] Specifically, the ligand compound may be a C3-C20 alkynyl compound, a C3-C10 alkynyl compound, or a C3-C7 alkynyl compound. The molar ratio of the silver precursor to the ligand compound may be 1:0.1 to 10, preferably 1:0.2 to 7, and more preferably 1:0.5 to 5. This range is desirable as it allows for excellent synthesis efficiency while reducing reaction impurities.

[0116] In addition, the molar ratio of the silver precursor to the halide compound may be 1:0.01 to 0.5, preferably 1:0.02 to 0.3, and more preferably 1:0.03 to 0.2.

[0117] In one embodiment, the silver precursor may be one or more selected from AgNO3, AgBF4, AgCF3SO3, AgClO4, AgO2CCH3, and AgPF6, specifically one or more selected from AgNO3, AgBF4, and AgPF6, and more specifically AgNO3 or AgBF4, but is not limited thereto.

[0118] In addition, the method for preparing the silver nanocluster according to one embodiment may further include a step of precipitating and separating with a nonpolar solvent, and the nonpolar solvent used therein may be one or more selected from n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cis-cyclooctene, toluene, m-, o-, p-xylene, t-butylmethyl ether, and di-n-butyl ether, specifically one or more selected from n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and cis-cyclooctene, and more specifically one or more selected from n-pentane, n-hexane, and n-heptane, but is not limited thereto.

[0119] In one embodiment, the halide compound may be an alkali metal salt, specifically LiCl, NaCl, KCl, LiF, NaF, LiBr, NaBr, KBr, LiI, KI, and more preferably NaCl.

[0120] In a method for manufacturing a catalyst according to one embodiment, the step of electrochemically treating the mixture may include: a step of dispersing a mixture obtained by mixing a silver precursor, a ligand compound, and a halide compound onto a working electrode; a step of preparing another counter electrode and a reference electrode; and a step of applying a potential of -3.0 to -0.01 V to the working electrode. Specifically, the reference electrode may be Ag / AgCl, and the counter electrode may include nickel, but is not limited thereto.

[0121] In one embodiment, the working electrode may be a porous electrode, and more specifically, may be a porous electrode based on any one metal selected from the group consisting of carbon, nickel, and silver, but is not limited thereto.

[0122] In addition, the step of applying the above potential may be performed for 1 minute to 10 hours, and preferably for 30 minutes to 3 hours.

[0123] More specifically, a schematic diagram of the electrochemical treatment step of the present invention is shown in FIG. 2, and through this step, the ligand of the silver nanocluster catalyst is detached to expose the silver active site, thereby significantly improving the carbon dioxide conversion activity.

[0124] In addition, the manufacturing method of the catalyst described above has high industrial utility value because it enables mass production with high yield due to the characteristics of silver ions that gather around anions.

[0125] Hereinafter, the silver nanocluster catalyst for carbon dioxide conversion according to the present invention, the gas diffusion electrode including the same, the zero-gap reactor including the same, and the method for converting carbon dioxide using the same will be explained in more detail through specific embodiments.

[0126] However, the following examples are merely for reference to explain the invention in detail, and the invention is not limited thereto and may be implemented in various forms. Furthermore, the terms used in the description of the invention are intended only to effectively describe specific embodiments and are not intended to limit the invention.

[0127] [Preparation Example 1] [Ag 14 (C≡CtBu) 12 Cl] + Nanocluster manufacturing

[0128] 0.097 g (0.5 mmol) of AgBF4, 0.061 mL (0.5 mmol) of t-butylacetylene, 0.070 mL (0.5 mmol) of triethylamine, and 0.011 g (0.04 mmol) of tetrabutylammonium chloride were added to a flask, and 1 mL of tetrahydrofuran was added and stirred for 4 hours. The solvent was removed by vacuum distillation, and after removing impurities by washing with pure water and n-pentane, [Ag 14 (C≡CtBu) 12 Cl] + I obtained a nanocluster.

[0129] It was confirmed that the ESI-MS analysis graph of the nanoclusters fabricated in Figure 3 matches the theoretical values.

[0130] [Preparation Example 2] [Ag through electrochemical treatment 14 (C≡CtBu)8Cl] + Nanocluster manufacturing

[0131] [Ag obtained in Preparation Example 1 14 (C≡CtBu) 12 Cl] + 0.5 mg of nanoclusters at 100 cm 2It is fixed to a porous electrode. This electrode is used as the working electrode, another porous nickel electrode as the counter electrode, and Ag / AgCl as the reference electrode. A constant potential of -2.0 V (vs. Ag / AgCl) is applied to the working electrode for 1 hour in a 1.0 M KOH solution. After washing the working electrode with pure water and diethyl ether, the electrochemically treated [Ag 14 (C≡CtBu)8Cl] + Nanoclusters were obtained.

[0132] The UV-vis and EXAFS (Extended X-ray Absorption Find Structure) result spectra of the nanoclusters prepared in Preparation Examples 1 and 2 are shown in Figures 4 and 5, respectively. Through the UV-vis results, it was confirmed that the overall structure of the clusters was maintained after electrochemical treatment.

[0133] In addition, in the EXAFS result spectrum, it was confirmed that the Ag-C peak of the nanocluster of Preparation Example 2 was reduced compared to the nanocluster of Preparation Example 1, thereby confirming that the ligand of the catalyst was detached through the electrochemical treatment step.

[0134] [Preparation Example 3] [Ag 14 (C≡CtBu)8F] + Nanocluster manufacturing

[0135] [Ag 14 (C≡CtBu) 12 F] + Nanoclusters prepared in Example 2 [Ag 14 (C≡CtBu) 12 Cl] + Instead, it was used, and subjected to the same electrochemical treatment [Ag 14 (C≡CtBu)8F] + Nanoclusters were obtained.

[0136] [Preparation Example 4] [Ag 14 (C≡CtBu)8Br] + Nanocluster manufacturing

[0137] The procedure was carried out in the same manner as Preparation Example 1, except that 0.04 mmol of tetrabutylammonium bromide was used instead of tetrabutylammonium chloride in Preparation Example 1.

[0138] [Preparation Example 5] Aqueous solution-based [Ag 14 (C≡CtBu)8Cl] + Nanocluster manufacturing

[0139] 40.100 g (0.51 mmol) of AgBF is placed in a flask, and 5 mL of pure water is added to dissolve it. Subsequently, 0.054 mL (0.44 mmol) of t-butylacetylene and 0.004 g (0.07 mmol) of sodium chloride are added to the solution, and the mixture is stirred for 12 hours. Cluster catalysts are formed and precipitated due to differences in solubility. After removing impurities by washing with pure water and n-pentane, [Ag 14 (C≡CtBu) 12 Cl] + Nanoclusters were obtained and electrochemically treated in the same manner as in Preparation Example 2 [Ag 14 (C≡CtBu)8Cl] + I obtained a nanocluster.

[0140] [Preparation Example 6] Aqueous solution-based [Ag 14 (C≡CtBu)8F] + Nanocluster manufacturing

[0141] The procedure was carried out in the same manner as Preparation Example 5, except that 0.07 mmol of sodium fluoride was used instead of sodium chloride in Preparation Example 5.

[0142] [Preparation Example 7] Aqueous solution-based [Ag 14 (C≡CtBu)8Br] + Nanocluster manufacturing

[0143] The procedure was carried out in the same manner as Preparation Example 5, except that 0.07 mmol of sodium bromide was used instead of sodium chloride in Preparation Example 5.

[0144] The UV-Vis result spectra of the nanoclusters prepared in Preparation Examples 5 to 7 above are shown in Fig. 6.

[0145] [Example 1]

[0146] A solution of 170 μg of the nanoclusters obtained in Preparation Example 2 above dissolved in 160 μL of dichloromethane was mixed with 160 μL of acetone, and ultrasonic dispersion was performed for about 1 minute to prepare a nanocluster composite dispersion. Next, the prepared nanocluster composite dispersion was [described] as follows: 2.5 x 2.5 cm 2 A nanocluster composite gas diffusion electrode was fabricated by solution deposition on a gas diffusion type micropore carbon electrode (GDE (W1S1011, Ce-Tech)), and the average nanocluster loading amount was 10.6 nmol / cm² 2 It was measured as.

[0147] Using the above-manufactured gas diffusion electrode as the cathode, 3x3 cm 2 A zero-gap reactor was manufactured by using a Ni foam (NiF, 29-04275-01, Invisible Inc.) of a certain area as the anode, placing an AEM (Sustainion® X37-50, RT grade, Dioxide Materials) membrane pretreated with 1.0 M KOH between the cathode and the anode, and compressing it using stainless steel.

[0148] [Example 2]

[0149] The above Example 1 was performed in the same manner as Example 1, except that Preparation Example 5 was used instead of Preparation Example 2.

[0150] [Example 3]

[0151] The above Example 1 was performed in the same manner as Example 1, except that Preparation Example 6 was used instead of Preparation Example 2.

[0152] [Example 4]

[0153] The above Example 1 was performed in the same manner as Example 1, except that Preparation Example 7 was used instead of Preparation Example 2.

[0154] [Comparative Example 1]

[0155] The above Example 1 was performed in the same manner as Example 1, except that Preparation Example 1 was used instead of Preparation Example 2.

[0156] [Experimental Example 1]

[0157] Carbon dioxide conversion was performed using the zero-gap reactors of Examples 1 to 4 and Comparative Example 1.

[0158] CO2 gas containing water vapor was supplied to the cathode at 30 sccm while a 1.0 M KOH solution was circulated at a flow rate of 3 mL / min. A cold trap was installed at the cathode outlet to remove moisture generated from the water vapor, and finally, the final product was analyzed by connecting to a gas chromatograph. Example 2 had the same structure as Example 1 and showed the same results.

[0159] Figures 7 and 8 show the results of the carbon dioxide conversion activity of Example 1 and Comparative Example 1, and it can be seen that the nanoclusters of the example show a significantly improved carbon dioxide conversion rate.

[0160] In addition, Figures 9 and 10 show the electrochemical activity results of Example 1 and Comparative Example 1, and it can be seen that the nanoclusters of the Example have high electrochemical activity compared to the Comparative Example.

[0161] In addition, the electrochemical activity results of Examples 2 to 4 are shown in Figure 11, and it was confirmed that a catalyst with excellent carbon dioxide conversion performance was prepared even in an aqueous solution.

[0162] Thus, the silver nanocluster of the present invention is very economical compared to gold (Au)-based catalysts and can exhibit superior carbon dioxide conversion activity compared to silver (Ag)-based catalysts, so a gas diffusion electrode or zero-gap reactor to which it is applied can be industrially very useful as a high-performance electrochemical carbon dioxide conversion system.

[0163] In addition, the silver nanoclusters of the present invention not only provide a simple and eco-friendly manufacturing process but also enable mass production with high yield, making them highly valuable for industrial use.

[0164] As described above, the present invention has been explained by specific details, limited embodiments, and comparative examples; however, these are provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

[0165] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention.

Claims

Claim 1 Silver nanocluster catalyst for carbon dioxide conversion represented by the following chemical formula 1. [Chemical Formula 1]XAg 14 (R 1 ) n [In the above chemical formula 1, R 1 C3-C 10 It is alkynyl; X is a halogen; and n is an integer from 6 to 11. Claim 2 In claim 1, R of the above chemical formula 1 1 A silver nanocluster catalyst for carbon dioxide conversion, wherein silver is a C3-C7 alkynyl; X is a halogen; and n is an integer from 6 to 11. Claim 3 In claim 1, R of the above chemical formula 1 1 A silver nanocluster catalyst for carbon dioxide conversion, wherein C≡CtBu; X is a halogen; and n is an integer from 6 to 11. Claim 4 delete Claim 5 A gas diffusion electrode for carbon dioxide conversion comprising a porous support and a silver nanocluster catalyst according to any one of claims 1 to 3 immobilized in the pores of the porous support. Claim 6 In paragraph 5, the above porous support is a carbon chain, a gas diffusion electrode for carbon dioxide conversion. Claim 7 A gas diffusion electrode for carbon dioxide conversion according to claim 5, wherein the average pore size of the porous support is 10 to 1000 nm. Claim 8 A gas diffusion electrode for carbon dioxide conversion according to claim 5, wherein the average particle size of the silver nanoclusters is 1 to 5 nm. Claim 9 In claim 5, the silver nanocluster catalyst has a density of 1 to 100 nmol / cm² per unit area of ​​the porous support. 2 A gas diffusion electrode for carbon dioxide conversion, supported at a density of Claim 10 A zero-gap reactor for carbon dioxide conversion comprising: an anode; a cathode comprising a silver nanocluster according to any one of claims 1 to 3; and a separator located between the cathode and the anode. Claim 11 A zero-gap reactor for carbon dioxide conversion according to claim 10, wherein the cathode is positioned in contact with one side of a separator. Claim 12 A zero-gap reactor for carbon dioxide conversion, wherein the anode is one or more selected from nickel, iron, and iridium. Claim 13 In item 10, the above-mentioned membrane is an ion exchange membrane, a zero-gap reactor for carbon dioxide conversion. Claim 14 A method for converting carbon dioxide, comprising: a step of supplying carbon dioxide to one side of a cathode of a zero-gap reactor for converting carbon dioxide; and a step of obtaining carbon monoxide converted from carbon dioxide from one side of the cathode; wherein the zero-gap reactor for converting carbon dioxide is a zero-gap reactor for converting carbon dioxide according to claim 10. Claim 15 A method for preparing a silver nanocluster catalyst for carbon dioxide conversion, comprising the steps of: mixing a silver precursor, a ligand compound, an alkylammonium halide, and a reducing agent; and electrochemically treating the mixture; for preparing a silver nanocluster represented by the following Chemical Formula 1. [Chemical Formula 1] XAg 14 (R 1 ) n [In the above chemical formula 1, R 1 C3-C 10 It is alkynyl; X is a halogen; and n is an integer from 6 to 11. Claim 16 In item 15, the above R 1 Method for preparing a silver nanocluster catalyst for carbon dioxide conversion, which is a C3-C7 alkynyl. Claim 17 A method for preparing a silver nanocluster catalyst for carbon dioxide conversion according to claim 15, wherein the molar ratio of the silver precursor to the alkylammonium halide is 1:0.01 to 0.

5. Claim 18 A method for preparing a silver nanocluster catalyst for carbon dioxide conversion according to claim 15, wherein the silver precursor is one or more selected from AgNO3, AgBF4, AgCF3SO3, AgClO4, AgO2CCH3, and AgPF6. Claim 19 A method for preparing a silver nanocluster catalyst for carbon dioxide conversion, comprising the steps of: mixing a silver precursor, a ligand compound, and a halide compound in an aqueous solution; and electrochemically treating the mixture; for preparing a silver nanocluster represented by the following Chemical Formula 1. [Chemical Formula 1] XAg 14 (R 1 ) n [In the above chemical formula 1, R 1 C3-C 10 It is alkynyl; X is a halogen; and n is an integer from 6 to 11. Claim 20 In Clause 19, the above R 1 Method for preparing a silver nanocluster catalyst for carbon dioxide conversion, which is a C3-C7 alkynyl. Claim 21 A method for preparing a silver nanocluster catalyst for carbon dioxide conversion, wherein, in claim 19, the halide compound is an alkali metal salt.

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