MEA for carbon dioxide reduction comprising two-layer structure reduction catalyst layer cathode, assembly for carbon dioxide reduction comprising MEA, and method for manufacturing same mea

Abstract

The present invention relates to a technology for a membrane electrode assembly (MEA) for carbon dioxide reduction. In particular, the present invention relates to a technology capable of addressing the problem of an acidic environment occurring, which is unfavorable to the cathode reaction during a catalytic reaction when a cation exchange membrane is used as a separator, maintaining an advantageous alkaline environment, and suppressing the hydrogen evolution reaction (HER), which is a side reaction.

Description

MEA for carbon dioxide reduction including a two-layer structure reduction catalyst layer cathode, an assembly for carbon dioxide reduction including the MEA, and a method for manufacturing the MEA

[0001] The present invention relates to a technology for an MEA (Membrane Electrode Assembly) including a cation exchange membrane, a method for manufacturing the MEA, and an assembly for carbon dioxide reduction including the MEA, and more particularly, to a novel technology capable of solving problems occurring when applying a cation exchange membrane by improving a cathode reduction catalyst layer.

[0002] As the use of fossil fuels increases, global warming is worsening due to the increasing amount of carbon dioxide, and research is continuously being conducted to solve this problem.

[0003]

[0004] The electrochemical carbon dioxide reduction reaction (CO2R) (abbreviated as "CO2RR") is attracting attention as a method for reducing carbon dioxide and converting it into high-value-added compounds such as carbon monoxide and ethylene. CO2RR technology, utilizing cation or anion exchange membranes, is attracting attention due to its low resistance between electrodes and high scalability.

[0005]

[0006] Over the past several decades, significant progress has been made in the development of CO2RR electrode assemblies using anion exchange membranes. These electrode assemblies are widely known as assemblies for converting CO2 into useful substances such as carbon monoxide and ethylene with high selectivity and current density. However, HCO3 generated during the CO2RR process using anion exchange membranes is a major issue. - , CO2 2-Anions such as CO2RR and the liquid product crossover through the anion exchange membrane, which not only lowers the CO2 conversion rate, but also has the problem that the anion exchange membrane has low mechanical and chemical stability, which limits its industrialization potential. In addition, the CO2RR electrode assembly using the anion exchange membrane has the disadvantage of requiring an additional process, including the capture and reuse of CO2, on the anode side due to the crossover of CO2.

[0007]

[0008] Recently, to overcome the above limitations of anion exchange membrane (AEM), Nafion ® Electrode assemblies (MEAs) using cation exchange membranes (CEMs) are preferred. Cation exchange membranes are widely used in electrochemistry due to their high stability and proton conductivity. For CO2 reduction, it is advantageous to maintain an alkaline state on the cathode side during the reduction reaction. However, the high proton conductivity of cation exchange membranes induces an acidic reaction environment on the cathode side, which reduces the selectivity of CO2RR and promotes the hydrogen evolution reaction (HER).

[0009] The purpose of the present invention is to provide a technology that can suppress the hydrogen generation reaction, which is a problem that occurs when using a cation exchange membrane in CO2RR, and exhibit high carbon dioxide conversion efficiency.

[0010]

[0011] In addition, it is an object of the present invention to provide an electrode structure for an electrode assembly of a cation ion exchange membrane having a high CO2RR Faradaic efficiency.

[0012] The present invention provides a CO2 reduction MEA comprising a cathode layer including a gas diffusion layer (GDL) and a catalyst layer; a cation exchange membrane (CEM); and an anode layer including an oxidation catalyst, in order to achieve the above object, wherein the catalyst layer of the cathode layer includes a first layer formed on the gas diffusion layer and including a reduction catalyst and an anion exchange ionomer; and a second layer formed on the first layer and including a carbon-based mixture and an anion exchange ionomer.

[0013]

[0014] In particular, the reduction catalyst may be at least one selected from Ag, Au, Zn, Cu, and In.

[0015]

[0016] In particular, the reduction catalyst is 0.5 mg / cm 2 3 mg / cm 2 can be used as the content of.

[0017]

[0018] In particular, the reduction catalyst particle size may be in the form of nanoparticles of 10 nm or less, in the form of secondary particles in which the nanoparticles are aggregated, in the form of single particles having an average particle diameter of 0.01 to 2 μm, or in the form of a mixture thereof.

[0019]

[0020] In particular, the carbon-based mixture may be at least one of carbon black, carbon nanotubes, graphene, carbon nanofibers, and graphitized carbon black.

[0021]

[0022] In particular, the carbon-based mixture may be included in an amount of 20 to 300 parts by weight based on 100 parts by weight of the reduction catalyst.

[0023]

[0024] In particular, in the first layer, the anion exchange ionomer may be included in an amount of 50 to 1000 parts by weight based on 100 parts by weight of the reduction catalyst.

[0025]

[0026] In addition, the present invention provides an assembly for CO2 reduction using the above MEA.

[0027]

[0028] In addition, the present invention provides a method for manufacturing an MEA for CO2 reduction, comprising the steps of: preparing a gas diffusion layer; coating a mixed solution of a reduction catalyst, an anion exchange ionomer, and a solvent on the gas diffusion layer to manufacture a first layer; and coating a mixed solution of a carbon-based mixture and an anion exchange ionomer on the first layer to manufacture a second layer, after which a cathode layer is manufactured, and then laminating a cation exchange membrane and an anode layer on the cathode layer.

[0029]

[0030] In particular, the step of manufacturing the first layer and the step of manufacturing the second layer may each further include a drying process.

[0031]

[0032] The MEA using the cation exchange membrane according to the present invention has high current density and selectivity, and thus can be effectively utilized in a carbon dioxide reduction reaction (CO2RR) system.

[0033]

[0034] When the carbon-based support is present in a layered structure separately from the reduction catalyst as in the present invention, more cations (e.g., K when KHCO3 is used as the electrolyte) are present on the electrode. ＋ ) can be confirmed to exist. It can be confirmed that the same components as in the example of the present invention, but the layered structure of the two-layer structure is more like a mixed structure of the same components as in Comparative Example 3 than the layered structure of the two-layer structure of the cation (K ＋ ) can be confirmed to be more advantageous in preserving it.

[0035]

[0036] In addition, when the MEA of the present invention was applied, the movement of water was almost suppressed, but the catalyst manufactured in Comparative Example 1 had a problem of being completely wetted by the moved water.

[0037]

[0038] In addition, as in the present invention, when a mixture of carbon and anion ionomer is present in the buffer layer, the faradaic efficiency of carbon monoxide is the highest, and as in Comparative Example 1, when there is no carbon, it can be confirmed that the faradaic efficiency of carbon monoxide decreases rapidly at high current even when the buffer layer is present.

[0039]

[0040] In addition, in the case of Comparative Example 2, when there is no catalyst structure buffer layer, H is released from the cation exchange membrane. + The acidity around the silver nano catalyst increases as it is transferred, thereby increasing the hydrogen generation reaction. In the case where the buffer layer composed only of anion exchange ionomers is present in the catalyst structure of Comparative Example 1, the anions generated in the carbon dioxide reduction reaction and the H transferred from the cation exchange membrane + reacts in the buffer layer to regenerate carbon dioxide and maintains the vicinity of the silver nano catalyst in a neutral state. However, low cation (K + ) concentration, CO2RR decreases at high currents. On the other hand, when a buffer layer composed of an anion exchange ionomer and a carbon black mixture is present in the catalyst structure of the present invention, the porous carbon structure absorbs anions generated from CO2RR and H transferred from the cation exchange membrane. + It reacts in the buffer layer to promote carbon dioxide regeneration and has high cation (K + ) maintains CO2RR performance to some extent at high currents due to the concentration.

[0041]

[0042] When using the electrode catalyst of the present invention, a high current density (300 mA cm) is achieved at a pressure of 1 bar. -2) and the performance of CO2RR was maintained at 350 mA cm when the pressure was applied up to 5 bar. -2 It can be confirmed that CO2RR is dominant over hydrogen reaction.

[0043] Figure 1 is a schematic diagram for explaining the structural differences of the electrode catalysts manufactured in Examples and Comparative Examples 1 to 3.

[0044] Figure 2 is a scanning electron microscope (SEM) photograph and an energy dispersive spectroscopy (EDS) photograph of the electrode catalysts manufactured in Examples 1 to 3 after the carbon dioxide conversion reaction.

[0045] Figure 3 shows the results of in-situ micro-computed tomography of the electrode catalysts manufactured in Example (lower drawing) and Comparative Example 1 (upper drawing).

[0046] Figures 4a and 4b illustrate the voltage (Figure 4a) and the faradaic efficiency (Figure 4b) of the product according to the structure of the electrode catalyst manufactured in Examples and Comparative Examples 1 to 3.

[0047] Figure 5 illustrates the reaction environment of the catalysts manufactured in Examples, Comparative Example 1, and Comparative Example 2.

[0048] Figure 6 illustrates a system for pressurizing CO2 in an electrode assembly using an electrode catalyst and a cationic membrane manufactured in an embodiment.

[0049] Figure 7a shows the results of measuring the faradaic efficiency of carbon monoxide and hydrogen according to pressure using the pressurized carbon dioxide conversion device and pressurized electrolytic cell schematically illustrated in Figure 6, using the catalyst electrode manufactured in Comparative Example 1, and Figure 7b shows the results of measuring the faradaic efficiency of carbon monoxide and hydrogen according to pressure using the catalyst electrode manufactured in the Example.

[0050] Figure 8 shows the carbon monoxide faradaic efficiency measured using a carbon dioxide conversion device at atmospheric pressure and 5 bar pressure for the catalyst electrodes manufactured in Example and Comparative Example 1, respectively.

[0051] The present invention relates to a CO2 reduction MEA comprising a cathode layer including a gas diffusion layer (GDL) and a catalyst layer; a cation exchange membrane (CEM); and an anode layer including an oxidation catalyst, wherein the catalyst layer of the cathode layer comprises a first layer including a reduction catalyst formed on the gas diffusion layer and an anion exchange ionomer; and a second layer including a carbon-based mixture formed on the first layer and an anion exchange ionomer.

[0052]

[0053] The present invention discloses a technique for improving a cathode layer to solve the problem of acidification of the cathode side during reaction, which is a problem when using a cation exchange membrane. The cathode layer is similar to the prior art in that it includes a gas diffusion layer (GDL) and a catalyst layer. In the present invention, in addition to a reduction catalyst, the catalyst layer further includes a carbon-based mixture and an anion exchange ionomer.

[0054]

[0055] FIG. 1 is a drawing explaining the cathode structure of the present invention (embodiment) and comparative examples 1 to 3.

[0056]

[0057] Referring to FIG. 1, the present invention is formed as a double layer including a first layer including a reduction catalyst and an anion exchange ionomer formed on a gas diffusion layer; and a second layer including a carbon-based mixture and an anion exchange ionomer formed on the first layer.

[0058]

[0059] Here, the first layer can be manufactured by applying and drying a mixed solution of a reduction catalyst, for example, silver nanoparticles and an anion exchange ionomer, on a gas diffusion layer, and then increasing the temperature after application to volatilize the solvent to manufacture the first layer.

[0060]

[0061] Meanwhile, the second layer can be manufactured by applying and drying a mixed solution of a carbon-based mixture and an anion exchange ionomer on the first layer, and the second layer can also be manufactured by increasing the temperature after application to evaporate the solvent.

[0062]

[0063] Meanwhile, Comparative Example 1 is a two-layer structure comprising a first layer of a reduction catalyst and an anion exchange ionomer on a gas diffusion layer, and an anion exchange ionomer layer formed on the first layer. Unlike the examples of the present invention, the second layer does not contain a carbon-based mixture. Comparative Example 2 is a single-layer structure of a reduction catalyst and an anion exchange ionomer on a gas diffusion layer. Comparative Example 3 is a single-layer structure of a reduction catalyst, a carbon-based mixture, and an anion exchange ionomer.

[0064]

[0065] A carbon dioxide reduction device including an MEA of the present invention is formed by combining the MEA with a carbon dioxide supply unit on the cathode side and a water supply unit on the anode side. The carbon dioxide reduction device applying the MEA of the present invention can produce carbon monoxide through a carbon dioxide reduction reaction by performing an oxygen generation reaction through water electrolysis on the anode side and flowing humidified carbon dioxide gas on the cathode side. The carbon dioxide reduction device has high selectivity by applying an electrode catalyst for carbon dioxide reduction suitable for a cation exchange membrane. In the carbon dioxide reduction device, a catalyst advantageous for the oxygen generation reaction, such as iridium oxide, is used as the anode by coating it on a metal mesh. In the present invention, a cation exchange membrane is used between the two electrodes to prevent products generated at both the anode and cathode from mixing.

[0066]

[0067] The Membrane Electrode Assembly (MEA), which is an assembly of an anode, cathode, and membrane for carbon dioxide reduction, is a well-known technology, so a detailed description of each component will be omitted.

[0068]

[0069] Each ingredient is described in detail below.

[0070]

[0071] reduction catalyst

[0072]

[0073] The reduction catalyst typically uses metal nanoparticles. The metal nanoparticles have a catalytic activity capable of reducing carbon dioxide. For example, the metal nanoparticles may include at least one selected from gold (Au), silver (Ag), zinc (Zn), copper (Cu), indium (In), and alloys thereof, but are not limited thereto. For example, the metal nanoparticles may be silver nanoparticles. Silver (Ag) can reduce carbon dioxide with high selectivity and current density to produce carbon monoxide. The content of the metal nanoparticles is 0.5 mg / cm per unit area of ​​the gas diffusion layer. 2 3 mg / cm 2It can be applied in a range. The metal nanoparticles may be distributed in the form of very small nanoparticles of about 10 nm or less, for example, 1 to 10 nm, or may be in the form of secondary particles in which these nanoparticles are aggregated, or may be in the form of single particles having an average particle diameter of 0.01 to 2 ㎛, or may be in the form of a mixture thereof. For example, the metal particles may be in the form of secondary particles in which small particles of several nanometers or less exist on the surface of the carbon-based mixture and at the same time, nanoparticles are aggregated. The average particle diameter of the aggregated secondary particles may be in the range of, for example, 0.05 to 1.5 ㎛, specifically, for example, 0.1 to 1 ㎛. The form of the metal nanoparticles is not limited thereto and may exist in any form.

[0074]

[0075] carbon-based mixture

[0076]

[0077] The above carbon-based mixture may include, for example, at least one selected from carbon black, carbon nanotubes, graphene, carbon nanofibers, and graphitized carbon black. In particular, carbon black may be used as the carbon-based mixture to help improve current density. In the present invention, the carbon-based mixture may increase the thickness of the electrode catalyst layer, thereby increasing the pH of the electrode, thereby improving the carbon dioxide reduction efficiency. In the present invention, the content of the carbon-based mixture may be used in a range of 20 to 300 parts by weight based on 100 parts by weight of the metal nanoparticles, which are reduction catalysts. In the above range, the carbon-based mixture mixed with the metal nanoparticles can effectively increase the thickness of the metal nanoparticle layer, thereby maintaining a high pH, ​​thereby exhibiting a high CO2RR selectivity.

[0078]

[0079] In the present invention, the carbon-based mixture can be formed by mixing the nanoparticle reduction catalyst with a solvent and then coating it on a gas diffusion layer.

[0080]

[0081] anion exchange ionomer

[0082]

[0083] The anion exchange ionomer may wrap around the metal particle and cover the surface of the metal particle. The content of the anion exchange ionomer may be in the range of 20 to 300 parts by weight based on 100 parts by weight of the metal nanoparticle. In the above range, the anion exchange ionomer mixed with the metal nanoparticle effectively wraps the surface of the metal nanoparticle and hydrogen ions (H + ) can exhibit high CO2RR selectivity by suppressing the transmission of CO2RR.

[0084]

[0085] Examples of anion exchange ionomers include Dioxide XA-9, XC-1, XC-2 anionic ionomers, Fumatech FAA-3 anionic ionomer, PiperiON anionic ionomer, quaternary ammonium based polymers, and imidazolium based polymers.

[0086]

[0087] The following examples and comparative examples illustrate exemplary implementations in more detail. Examples and Comparative Examples 1 to 3 were manufactured with the same structure as Fig. 1. However, the examples and comparative examples are intended to illustrate technical concepts and do not limit the scope of the present invention.

[0088]

[0089] Example: Fabrication of a mixed layered electrode of silver nanoparticles, anion exchange ionomer, and carbon support (denoted as Ag / AEI-C)

[0090]

[0091] Silver nanoparticles (average particle size of 20-40 nm) were used as a reduction catalyst for the cathode. 30 mg of silver nanoparticles and 15 mg of anion exchange ionomer (abbreviated as AEI, XA-9 from Dioxide, the same as in the following experiment) were dissolved in 2 mL of ethanol and sonicated for about 20 minutes to prepare a well-dispersed solution. The solution was placed on a gas diffusion layer (GDL) (Fuelcellstore, Sigracet 39BC) with a micro porous layer (MPL) at a concentration of cm 2 The first layer was manufactured by applying 1 mg of silver nanoparticles and heating to 70°C to allow the solution to dry quickly.

[0092]

[0093] 15 mg of carbon black (KB600J) and 75 mg of anion exchange ionomer were dissolved in 2 ml of ethanol and ultrasonicated for about 20 minutes to prepare a well-dispersed solution. The solution was applied on the first layer in a cm 2 After applying 0.5 mg of carbon black as a standard, the solution was heated to 70°C to quickly dry, and a second layer was formed on the first layer to produce a two-layer catalyst layer.

[0094]

[0095] Comparative Example 1: Fabrication of silver nanoparticle, anion exchange ionomer layered electrode (denoted as Ag / AEI)

[0096]

[0097] A well-dispersed solution was prepared by dissolving 30 mg of silver nanoparticles and 15 mg of anion exchange ionomer (AEI) in 2 mL of ethanol and sonicating for about 20 minutes. The solution was placed on a gas diffusion layer (GDL) (Fuelcellstore, Sigracet 39BC) with an MPL layer at a concentration of cm 2 After applying 1 mg of the sugar nanoparticles, the solution was heated to 70°C to quickly dry, thereby manufacturing a catalyst electrode.

[0098]

[0099] Afterwards, an ethanol solution containing 5 wt% of AEI was used on the catalyst layer prepared above. 2 After applying 2.5 mg of AEI per unit, the solution was heated to 70°C to quickly dry, thereby manufacturing a catalyst electrode.

[0100]

[0101] Comparative Example 2: Fabrication of anion-exchange ionomer-mixed silver nanoparticle electrode (indicated by Ag black)

[0102]

[0103] A well-dispersed solution was prepared by sonicating a catalyst mixed with 30 mg of silver nanoparticles and 15 mg of anion exchange ionomer in 2 ml of ethanol. As in the examples, the solution was placed on the GDL at cm 2 After applying 1 mg of sugar, the solution was heated to 90°C to quickly dry, thereby manufacturing a catalyst electrode.

[0104]

[0105] Comparative Example 3: Preparation of a mixed electrode of silver nanoparticles, anion exchange ionomer, and carbon (denoted as Ag-AEI-C)

[0106]

[0107] 30 mg of silver nanoparticles, 15 mg of carbon black (Carnbon black, KB600J), and 90 mg of anion exchange ionomer (AEI) were dissolved in 3 ml of ethanol and sonicated for about 20 minutes to prepare a well-dispersed solution. The solution was placed on a gas diffusion layer (GDL) (Fuelcellstore, Sigracet 39BC) with an MPL layer at a density of cm 2 After applying 1 mg of sugar nanoparticles, the solution was heated to 70°C to quickly dry, thereby manufacturing a catalyst electrode.

[0108]

[0109] The following experiments were conducted using the cathodes of the above examples and comparative examples 1 to 3.

[0110]

[0111] Experimental Example 1: SEM Evaluation

[0112]

[0113] Figure 2 shows scanning electron microscope (SEM) images and energy dispersive spectroscopy (EDS) analysis results after the CO2RR reaction of the electrode catalysts manufactured in Examples and Comparative Examples 1 to 3.

[0114]

[0115] As shown in Fig. 2, when comparing Example and Comparative Example 1, when the carbon-based support exists in a layered structure as in the present invention, more cations (K, which is the cation of KHCO3, the electrolyte used in the experiment) are present in the electrode. + ) was confirmed to exist. In addition, when comparing the example and comparative example 3, it was confirmed that the layered structure of the two-layer structure with the same components as the present invention was better than the mixed structure of the same components, but the cation (K + ) was found to be more advantageous in preserving the

[0116]

[0117] Experimental Example 2: Micro CT Evaluation

[0118]

[0119] Figure 3 shows the results of analysis using micro computed tomography after the electrode catalyst reaction manufactured in Example (lower drawing) and Comparative Example 1 (upper drawing).

[0120]

[0121] As shown in Fig. 3, the catalyst manufactured in the example had almost no movement of water, but the catalyst manufactured in Comparative Example 1 was confirmed to be completely wet by the moved water.

[0122]

[0123] Experimental Example 3: Evaluation of carbon dioxide conversion performance at atmospheric pressure

[0124]

[0125] Figures 4a and 4b are the experimental results for confirming the carbon dioxide conversion - carbon monoxide production ability of the electrode catalysts manufactured in Examples and Comparative Examples 1 to 3, and are the results of the current-voltage (Figure 4a) and the faradaic efficiency of carbon monoxide according to the amount of carbon-based support (Figure 4b), respectively. The system at this time used a Nafion 211 cation exchange membrane, and the anode catalyst was used by applying IrO2 to a Pt-coated Ti mesh. The electrolyte was 0.05 M KHCO3 and was passed through the anode, and 50 ccm of carbon dioxide was passed through the cathode. Figure 5 illustrates the reaction environment of the catalysts manufactured in Examples, Comparative Examples 1 and 2.

[0126]

[0127] As seen in Fig. 4a, it was confirmed that the voltage increased at the same current when a buffer layer was present in the catalyst structure.

[0128]

[0129] As shown in Fig. 4b, it was confirmed that the Faraday efficiency of carbon monoxide was high in the order of Ag / AEI-C of Example, Ag-AEI-C of Comparative Example 3, Ag / AEI of Comparative Example 1, and Ag black of Comparative Example 2. When a mixture of carbon and anionic ionomer was present in the buffer layer as in the present invention, the Faraday efficiency of carbon monoxide was the highest, and when there was no carbon-based mixture as in Comparative Example 1, it was confirmed that the Faraday efficiency of carbon monoxide rapidly decreased at high current even when a buffer layer was present.

[0130]

[0131] As shown in Fig. 5, in the case of Comparative Example 2 without a catalyst structure buffer layer, H is released from the cation exchange membrane. +The acidity around the silver nano catalyst increased as it was transferred, and the hydrogen generation reaction increased. When a buffer layer composed only of anion exchange ionomers was present in the catalyst structure of Comparative Example 1, the anions generated in the carbon dioxide reduction reaction and the H transferred from the cation exchange membrane + reacted in the buffer layer to regenerate carbon dioxide and maintained the area around the silver nano catalyst in a neutral state. However, low cation (K + ) concentration, CO2RR decreased at high currents. On the other hand, when a buffer layer composed of an anion exchange ionomer and a carbon black mixture is present in the catalyst structure of the embodiment of the present invention, the porous carbon structure absorbs anions generated in CO2RR and H transferred from the cation exchange membrane. + It reacts in the buffer layer to promote carbon dioxide regeneration and has high cation (K + ) maintained CO2RR performance to some extent at high current due to the concentration.

[0132]

[0133] Experimental Example 4: Evaluation of Carbon Dioxide Conversion Performance According to Pressure

[0134]

[0135] Figure 6 illustrates a system for pressurizing CO2 in an electrode assembly using an electrode catalyst and a cationic membrane manufactured in an embodiment.

[0136]

[0137] Figure 7a shows the results of measuring the faradaic efficiency of carbon monoxide and hydrogen according to pressure using the pressurized carbon dioxide conversion device and pressurized electrolytic cell schematically illustrated in Figure 6, using the catalyst electrode manufactured in Comparative Example 1, and Figure 7b shows the results of measuring the faradaic efficiency of carbon monoxide and hydrogen according to pressure using the catalyst electrode manufactured in the Example.

[0138]

[0139] As shown in Fig. 7a, it was confirmed that the faradaic efficiency of carbon monoxide increased as the pressure increased when the electrode catalyst of Comparative Example 1 was used. However, even at 5 bar, the applied current density was 250 mA cm-2 It was confirmed that when the hydrogen evolution reaction exceeds CO2RR, the reaction becomes more dominant than CO2RR.

[0140]

[0141] As shown in Fig. 7b, when using the electrode catalyst of the embodiment, a high current density (300 mA cm) is achieved at a pressure of 1 bar. -2 ) was confirmed to maintain the performance of CO2RR. In addition, when the pressure was applied up to 5 bar, 350 mA cm -2 It was confirmed that CO2RR was dominant over hydrogen reaction.

[0142]

[0143] Experimental Example 5: Evaluation of Electrode Catalyst Durability

[0144]

[0145] Figure 8 shows the carbon monoxide faradaic efficiency measured using a carbon dioxide conversion device at atmospheric pressure and 5 bar pressure for the catalyst electrodes manufactured in Example 1 and Comparative Example 1, respectively.

[0146]

[0147] In Experimental Example 5, durability evaluation was conducted, and 100 mA / cm 2The conditions were set to flow a constant current. A Pt-coated Ti mesh coated with IrO2 was used as the anode catalyst. 0.05 M KHCO3 was used as the electrolyte and flowed to the anode, and 50 ccm of carbon dioxide was flowed to the cathode. The electrode catalyst of Comparative Example 1 maintained a Faraday efficiency of 70% for 3 hours at atmospheric pressure, but then dropped sharply to 10% in 7 hours. On the other hand, the electrode catalyst of the Example maintained a Faraday efficiency of 70% for 6 hours at atmospheric pressure, but then dropped gradually to 50% in 12 hours. The electrode catalyst of Comparative Example 1 maintained a Faraday efficiency of 80% for 4 hours at 5 bar, but then dropped gradually to 50% in 12 hours. On the other hand, it was confirmed that the electrode catalyst of the Example maintained a Faraday efficiency of 80% for 12 hours at 5 bar.

[0148]

[0149] While preferred embodiments of the present invention have been described above with reference to the drawings and examples, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Accordingly, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. In a MEA for CO2 reduction, comprising a cathode layer including a gas diffusion layer (GDL) and a catalyst layer; a cation exchange membrane (CEM); and an anode layer including an oxidation catalyst, The catalyst layer of the above cathode layer is, A first layer comprising a reduction catalyst and an anion exchange ionomer formed on a gas diffusion layer; and A CO2 reduction MEA comprising a second layer comprising a carbon-based mixture formed on the first layer and an anion exchange ionomer.

2. In paragraph 1, the reduction catalyst is an MEA for CO2 reduction, wherein at least one of Ag, Au, Zn, Cu, and In is selected.

3. In paragraph 1, the reduction catalyst is 0.5 mg / cm 2 3 mg / cm 2 MEA for CO2 reduction.

4. In the first paragraph, the reduction catalyst particle size is in the form of nanoparticles of 10 nm or less, in the form of secondary particles in which the nanoparticles are aggregated, in the form of single particles having an average particle diameter of 0.01 to 2 ㎛, or in the form of a mixture thereof, MEA for CO2 reduction.

5. In paragraph 1, the carbon-based mixture is at least one of carbon black, carbon nanotubes, graphene, carbon nanofibers, and graphitized carbon black, a CO2 reduction MEA.

6. In paragraph 1, the carbon-based mixture is an MEA for CO2 reduction, which is included in an amount of 20 to 300 parts by weight based on 100 parts by weight of the reduction catalyst.

7. In the first paragraph, the anion exchange ionomer is included in an amount of 50 to 1000 parts by weight based on 100 parts by weight of the reduction catalyst, MEA for CO2 reduction.

8. An assembly for CO2 reduction, applying the MEA of any one of clauses 1 to 7.

9. Step of preparing a gas diffusion layer; A step of manufacturing a first layer by coating a mixed solution of a reduction catalyst, an anion exchange ionomer, and a solvent on the gas diffusion layer; and After manufacturing the cathode layer, including the step of manufacturing the second layer by coating a mixed solution of a carbon-based mixture and an anion exchange ionomer on the first layer, A method for manufacturing an MEA for CO2 reduction, comprising the step of laminating a cation exchange membrane and an anode layer on the cathode layer.

10. A method for manufacturing an MEA for CO2 reduction, wherein in paragraph 9, the step of manufacturing the first layer and the step of manufacturing the second layer each further include a drying process.

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