A CO2RR film electrode based on AEM system and its preparation method

Abstract

This invention relates to a CO2RR membrane electrode using an AEM system and its preparation method, comprising the following steps: S1, depositing a catalyst on one side of the gas diffusion layer relative to the etched anion exchange membrane, forming a cathode catalyst layer on one side of the gas diffusion layer; S2, etching the surface of the cathode catalyst layer using CF4 plasma to form an etched cathode catalyst layer; S3, an anion exchange membrane is provided on the surface of the etched cathode catalyst layer, and the surface of the anion exchange membrane is etched using plasma containing O2 to form an etched anion exchange membrane. In this invention, a fluorinated interface is constructed on the cathode catalyst layer, and its morphology and structure are ordered and controlled. The etched anion exchange membrane surface also develops a nanoscale rough structure. These two improvements effectively enhance the CO selectivity and stability of the membrane electrode.

Description

Technical Field

[0001] This invention relates to a CO2RR membrane electrode based on an AEM system and its preparation method. Background Technology

[0002] Currently, carbon dioxide (CO2) emissions continue to rise, and CO2 conversion technologies mainly include photocatalysis, biological fixation, thermocatalysis, and electrocatalysis. Among these, electrocatalytic reduction has become a cutting-edge research area due to its advantages of mild reaction conditions, flexible product control, and high energy efficiency. Electrochemical CO2 reduction reaction (CO2RR) technology can convert CO2 into high-value-added chemicals and clean fuels under mild conditions, and is one of the key pathways to promote energy structure transformation. Among the many reduction products, carbon monoxide (CO), as an important C1 chemical raw material and syngas component, has broad industrial application prospects.

[0003] Current CO2RR technology still faces a core bottleneck—how to simultaneously achieve high catalytic activity, high CO selectivity, and long-term operational stability at industrial-scale current densities, especially lacking a catalyst system that combines cost-effectiveness and superior performance. In the electrocatalytic reduction of CO2 to CO, gold (Au) and silver (Ag)-based catalysts exhibit excellent catalytic performance. However, the high cost of Au severely restricts its industrial application; while Ag offers cost advantages and high intrinsic selectivity, traditional preparation methods struggle to balance activity, stability, and the requirements for large-scale production.

[0004] In terms of reactor configuration, anion exchange membrane (AEM) electrolyzers are considered the most promising technology for industrial scale-up due to their high ion transport efficiency, low ohmic loss, and good system stability. The membrane electrode cathode, as the core component of CO2RR, has a catalyst layer that is the main site of electrochemical reactions, and its performance is regulated by multi-scale structure and multi-physics field coupling. Catalyst layers prepared by traditional slurry coating methods generally suffer from insufficient three-phase interface construction, low utilization of active sites, and catalyst agglomeration and deactivation, severely restricting breakthroughs in membrane electrode performance and lifespan improvement.

[0005] Although existing patented technologies (such as CN112410804A and CN116804279A) have proposed some electrode or catalyst preparation schemes, they still have significant shortcomings in terms of membrane electrode system integration verification under industrial operating conditions, product selectivity control and long-term durability, and have not yet met the requirements for large-scale industrialization. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome at least one of the defects of the existing membrane electrode for electrochemical carbon dioxide reduction, such as product selectivity and long-term durability, and to provide an AEM system CO2RR membrane electrode and its preparation method.

[0007] In the field of carbon dioxide electrochemical reduction (CO2RR), the cell pressure of the reduction reaction is generally high and it needs to be carried out in a strongly alkaline environment. Therefore, more stringent requirements are placed on the structural design and long-term stability of the membrane electrode, and the difficulty of implementation is also significantly increased.

[0008] The membrane electrode of the present invention has two aspects. On the one hand, a fluorinated interface is constructed on the cathode catalyst layer on the gas diffusion electrode, so that the morphology and structure of the cathode catalyst layer are ordered and controlled. On the other hand, a nanoscale rough structure is also constructed on the surface of the anion exchange membrane after etching. The above two improvements effectively enhance the CO selectivity and stability of the membrane electrode.

[0009] The present invention solves the above-mentioned technical problems through the following technical solution: In a first aspect, the present invention provides a method for preparing a CO2RR membrane electrode using an AEM system, the membrane electrode comprising a gas diffusion layer, an etched cathode catalyst layer, and an etched anion exchange membrane (AEM) sequentially disposed therefrom; the preparation method includes the following steps: S1. Deposit a catalyst on the side of the gas diffusion layer opposite to the etched anion exchange membrane (AEM) to form a cathode catalyst layer on one side of the gas diffusion layer; S2. The surface of the cathode catalyst layer is etched using CF4 plasma to form the etched cathode catalyst layer; the total amount of CF4 gas used in the etching is 10-250 scc. S3. An anion exchange membrane is provided on the surface of the etched cathode catalyst layer. The surface of the anion exchange membrane is etched using plasma containing O2 to form the etched anion exchange membrane. The total amount of etching gas used is 10-300 scc.

[0010] In this invention, the CO2RR membrane electrode of the AEM system generally refers to the core component used for the electrochemical reduction reaction of carbon dioxide (CO2RR) in an electrolyzer containing anion exchange membrane (AEM), namely the membrane electrode assembly (MEA).

[0011] Gas diffusion layer

[0012] In this invention, in step S1, the material and physicochemical parameters of the gas diffusion layer are conventionally selected in the art.

[0013] In this invention, in step S1, the gas diffusion layer can be carbon paper.

[0014] In this invention, in step S1, a hydrophobic layer may be provided on the side of the gas diffusion layer adjacent to the cathode catalyst layer.

[0015] In this invention, in step S1, the porosity of the gas diffusion layer can be 30%-80%, for example 50%-78%.

[0016] In some specific embodiments of the present invention, the gas diffusion layer is a gas diffusion layer of grade XGL-R-055 or a gas diffusion layer of grade TGPH060.

[0017] In this invention, in step S1, the gas diffusion layer generally needs to undergo plasma cleaning. The parameters for the plasma cleaning are conventionally selected in the art to effectively remove surface oxides and organic contaminants.

[0018] The background vacuum level of the plasma cleaning may not exceed 0.004 Pa.

[0019] The atmosphere for plasma cleaning can be argon or other inert gases.

[0020] The flow rate of the plasma cleaning atmosphere can be 150-200 sccm.

[0021] The working pressure of the plasma cleaning can be 0.2-0.5 Pa.

[0022] The plasma cleaning time can be 500-1000 s.

[0023] [Cathode catalyst layer (before etching)]

[0024] In this invention, in step S1, the material and physicochemical parameters of the cathode catalyst layer are conventionally selected in the art.

[0025] In this invention, in step S1, the active component of the cathode catalyst layer may be a noble metal. Preferably, the noble metal is Ag.

[0026] In this invention, in step S1, the thickness of the cathode catalyst layer can be 100-200 nm, for example 150 nm.

[0027] In this invention, in step S1, the areal density of the cathode catalyst layer can be 0.15-0.3 mg / cm³. 2 For example, 0.17-0.28 mg / cm³ 2 .

[0028] In this invention, in step S1, the porosity of the cathode catalyst layer can be 50%-80%.

[0029] In this invention, in step S1, the bonding force between the cathode catalyst layer and the gas diffusion layer can be 30-40 MPa, for example 32 MPa, 33 MPa, 35 MPa, 36 MPa, 37 MPa or 38 MPa.

[0030] In this invention, in step S1, the surface contact angle of the cathode catalyst layer can be 90°-100°, for example 93°, 95°, 97° or 100°.

[0031] Physical vapor deposition

[0032] In this invention, in step S1, physical vapor deposition can be used to form the cathode catalyst layer on the gas diffusion layer. The parameters are conventionally selected in the art.

[0033] The physical vapor deposition method can be magnetron sputtering.

[0034] The temperature of the physical vapor deposition is preferably 0-100℃.

[0035] The atmosphere for physical vapor deposition is preferably an inert atmosphere, such as an argon atmosphere.

[0036] The background vacuum level of the physical vapor deposition may not exceed 0.003 Pa.

[0037] The atmospheric flow rate for physical vapor deposition can be 150-200 sccm.

[0038] The working pressure of the physical vapor deposition is preferably 0.2-0.3 Pa.

[0039] The physical vapor deposition time is preferably 150-300 s, for example 200 s.

[0040]

CF4 Plasma Etching Parameters

[0041] In this invention, in step S2, the total amount of CF4 gas used for etching is preferably 100-250 scc, for example 125 scc.

[0042] In this invention, in step S2, the CF4 gas flow rate used for etching can be 20-50 sccm.

[0043] In this invention, in step S2, the background vacuum level of the etching can be ≤0.005 Pa.

[0044] In this invention, the etching time in step S2 can be 30-300 s, preferably 100-300 s, for example 150 s.

[0045] In this invention, in step S2, the radio frequency power of the etching can be 50-200 W.

[0046] In this invention, the etching temperature in step S2 can be 20-100℃.

[0047] In this invention, in step S2, the etching working pressure can be 0.5-2 Pa, for example 1 Pa.

[0048] [Etched cathode catalyst layer]

[0049] In this invention, the surface contact angle of the etched cathode catalyst layer can be 120°-160°, preferably 127°-155°, for example 128°, 135°, 137°, 140°, 145° or 155°.

[0050] In this invention, after etching, the cathode catalyst layer structure exhibits an orderly texture with uneven surfaces, increasing the surface roughness.

[0051] In some specific embodiments of the present invention, a hydrophobic layer is provided on the side of the gas diffusion layer adjacent to the cathode catalyst layer, the porosity of the gas diffusion layer is 30%-50%, and the surface contact angle of the etched cathode catalyst layer is 128°-140°.

[0052] In a specific embodiment of the present invention, a hydrophobic layer is provided on the side of the gas diffusion layer adjacent to the cathode catalyst layer, the porosity of the gas diffusion layer is 30%, the thickness of the cathode catalyst layer is 100 nm, and the surface contact angle of the etched cathode catalyst layer is 135°.

[0053] In a specific embodiment of the present invention, a hydrophobic layer is provided on the side of the gas diffusion layer adjacent to the cathode catalyst layer, the porosity of the gas diffusion layer is 30%, the thickness of the cathode catalyst layer is 200 nm, and the surface contact angle of the etched cathode catalyst layer is 128°.

[0054] In a specific embodiment of the present invention, a hydrophobic layer is provided on the side of the gas diffusion layer adjacent to the cathode catalyst layer, the porosity of the gas diffusion layer is 30%, the thickness of the cathode catalyst layer is 150 nm, and the surface contact angle of the etched cathode catalyst layer is 140°.

[0055] In a specific embodiment of the present invention, the porosity of the gas diffusion layer is 50%-80%, the thickness of the cathode catalyst layer is 180-200 nm, and the surface contact angle of the etched cathode catalyst layer is 150°-155°.

[0056] [Anion exchange membrane before etching]

[0057] In some specific embodiments of the present invention, the anion exchange membrane before etching is an anion exchange membrane of grade Sustainion X37-50 Grade 60.

[0058] In this invention, the anion exchange membrane before etching can be cleaned in a conventional manner. The specific steps include: placing the anion exchange membrane before etching in deionized water and anhydrous ethanol for ultrasonic cleaning in sequence for 10-20 minutes each time to thoroughly remove surface adsorbed contaminants; then placing it in a vacuum drying oven at 40-60℃ for 2-4 hours to ensure that the membrane surface is clean and the water content is within a controllable range.

[0059]

O2 plasma etching parameters

[0060] In this invention, the total amount of etching gas is preferably 100-200 scc, for example 166.7 scc.

[0061] In this invention, the etching atmosphere can be O2 and Ar. The volume ratio of O2 to Ar is preferably 1:(1-4).

[0062] In this invention, the total gas flow rate for etching can be 20-100 sccm.

[0063] In this invention, the etching time can be 30-300 s, for example 100-200 s.

[0064] In this invention, the etching working pressure can be 5-50 Pa, for example 27 Pa.

[0065] In this invention, the radio frequency power of the etching can be 50-200 W.

[0066] [Etched anion exchange membrane]

[0067] In this invention, the surface contact angle of the etched anion exchange membrane is 50°-65°, for example, 60°.

[0068] In this invention, the synergistic effect of etched ion bombardment and chemical reaction creates a nanoscale rough structure on the surface of the anion exchange membrane and introduces oxygen-containing polar functional groups to enhance surface hydrophilicity.

[0069] Secondly, the present invention provides a CO2RR membrane electrode of the AEM system prepared by the preparation method described above.

[0070] In this invention, the CO2RR membrane electrode of the AEM system is sequentially configured with a gas diffusion layer, an etched cathode catalyst layer, and an etched anion exchange membrane.

[0071] The surface contact angle of the etched cathode catalyst layer can be 120°-160°, preferably 127°-155°.

[0072] The surface contact angle of the etched anion exchange membrane can be 50°-65°, for example, 60°.

[0073] Thirdly, the present invention provides an etching method for anion exchange membranes as described above.

[0074] Fourthly, the present invention provides an anion exchange membrane prepared by the etching method described above.

[0075] In this invention, the surface contact angle of the etched anion exchange membrane can be 50°-65°, for example, 60°.

[0076] Fifthly, the present invention provides an electrolytic cell comprising an anode region and a cathode region, wherein the cathode region comprises a CO2RR membrane electrode of the AEM system as described above.

[0077] In this invention, as is customary, the assembly sequence of each component in the electrolytic cell loading process follows specific specifications: first, a titanium felt coated with iridium is placed; then, a PTFE sealing frame membrane matching the thickness of the titanium felt, an etched anion exchange membrane, a PTFE sealing frame membrane matching the thickness of the gas diffusion electrode, and the gas diffusion electrode (etched cathode catalyst layer and gas diffusion layer) are laid in sequence. After the above components are placed, a torque wrench is used to tightly compress the flow channel plates on both sides to ensure stability; the loading torque must be strictly controlled within 4-7 N·m.

[0078] Sixthly, the present invention provides an electrochemical carbon dioxide reduction method, which includes the following steps: S1. Provide an electrolytic cell as described above; S2. Apply current to the electrolytic cell; introduce electrolyte into the anode region; introduce a CO2 source into the cathode region.

[0079] In this invention, the conditions and parameters for the electrochemical carbon dioxide reduction are conventionally selected in the art.

[0080] In this invention, the temperature for the electrochemical carbon dioxide reduction can be 25-40℃.

[0081] In this invention, the CO2 source can be CO2 gas.

[0082] In this invention, the flow rate of the CO2 source can be 80-250 sccm, for example 200 sccm.

[0083] In this invention, the electrolyte can be an alkaline solution.

[0084] Preferably, the alkaline solution is an alkaline solution or a bicarbonate solution.

[0085] Preferably, the alkaline solution is a KOH solution.

[0086] The bicarbonate solution is preferably a KHCO3 solution.

[0087] In this invention, the concentration of the electrolyte can be 0.1-1 M.

[0088] In this invention, the flow rate of the electrolyte can be 25-100 ml / min, for example 50 ml / min.

[0089] The positive and progressive effects of this invention are as follows: (1) The membrane electrode of the present invention adopts plasma etching technology. On the one hand, by etching, fluorine elements are introduced into the cathode catalyst layer to construct a fluorinated interface layer and regulate the surface properties, so as to carry out ordered regulation of morphology and structure, making its structure stable and rich in three-phase interface, and effectively suppressing catalyst deactivation and aggregation at high potential. On the other hand, by etching, a nanoscale rough structure is constructed on the surface of the anion exchange membrane and oxygen-containing polar functional groups are introduced to improve the surface hydrophilicity. Through the above material-structure synergistic design, the technical bottleneck of high activity, high selectivity and high stability in the field of electrochemical carbon dioxide reduction is overcome. (2) The membrane electrode of the present invention, at 200 mA / cm 2 At current density, the cell voltage can be as low as 3.17 V, the CO Faraday efficiency FE(CO) can be stably above 85%, and the continuous operating life can reach more than 120 hours. The comprehensive performance indicators reach the leading level, providing a new way to solve the cost and efficiency problems of CO2RR catalysts. (3) In this invention, the cathode catalyst layer on the membrane electrode can be prepared by physical vapor deposition (PVD), which can achieve precise deposition of the target material under high vacuum environment, realize the orderly distribution and firm bonding of the cathode catalyst layer on the surface of the gas diffusion layer, and improve the intrinsic activity and anti-migration ability of the catalyst; thereby optimizing the interface between the catalyst and the membrane, effectively reducing the interface resistance, and significantly improving the ion transport efficiency and electrochemical stability. Attached Figure Description

[0090] Figure 1 SEM image (200×) of the gas diffusion electrode ② after etching; Figure 2SEM image (20000×) of the etched gas diffusion electrode ②; Figure 3 SEM image (50000×) of the etched gas diffusion electrode ②; Figure 4 SEM image (50000×) of the unetched gas diffusion electrode ②; Figure 5 SEM image (200×) of the etched gas diffusion electrode ④; Figure 6 SEM image (20000×) of the etched gas diffusion electrode ④; Figure 7 SEM image (20000×) of the etched anion exchange membrane ①; Figure 8 SEM image (20000×) of the unetched anion exchange membrane ①; Figure 9 This is a SEM image (10000×) of the anodic catalyst layer in the membrane electrode of the present invention; Figure 10 This is a schematic diagram of the membrane electrode structure of the present invention; Figure 11 The voltage stability curve of the membrane electrode in Example 3 is shown. Figure 12 The graph shows the Faraday efficiency stability of the membrane electrode in Example 3. Detailed Implementation

[0091] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0092] The specific details of the raw materials used in the following examples and comparative examples are listed below: Carbon paper, grade XGL-R-055, has a hydrophobic layer and a porosity of 30%.

[0093] Carbon paper, grade TGPH060, without a hydrophobic layer, with a porosity of 78%.

[0094] Anion exchange membrane, brand name Sustainion X37-50 Grade 60.

[0095] Example: Fabrication of membrane electrode

[0096] A method for preparing a membrane electrode is as follows: 1. The membrane electrode employs a gas diffusion electrode—using carbon paper as the substrate material, an ordered cathode catalyst layer is prepared on its surface using PVD technology. This technology allows for precise control of the noble metal loading based on a set deposition thickness. The specific preparation method of the gas diffusion electrode includes the following steps: (1) Gas Diffusion Layer (GDL) Pretreatment Steps: Commercially available carbon paper is placed in a magnetron sputtering device and subjected to plasma cleaning to effectively remove surface oxides and organic contaminants. Specific process parameters are as follows: background vacuum degree not higher than 0.004 Pa, argon as working gas, atmosphere flow rate set at 150 sccm, working pressure maintained at 0.2 Pa, and plasma cleaning time of 1000 s.

[0097] (2) Ag catalyst layer deposition step: The cleaned gas diffusion layer (GDL) surface is placed in a magnetron sputtering apparatus, and the Ag catalyst layer is prepared by adjusting the sputtering power, atmosphere, flow rate, temperature, and bias parameters. The specific process conditions are: temperature 100℃, background vacuum 0.003 Pa, argon flow rate 200 sccm, working pressure 0.3 Pa, sputtering power 150 W, substrate bias 0 V, and porosity 50%-80%.

[0098] (3) CF4 plasma etching: The gas diffusion layer with the deposited Ag catalyst layer is placed in the vacuum chamber of a plasma processing device (such as a reactive ion etching machine or a magnetron sputtering device equipped with a CF4 gas path). The surface is modified using CF4 plasma to introduce fluorine, construct a fluorinated interface layer, and regulate surface properties. The specific process parameters are as follows: base vacuum degree ≤0.005 Pa; working gas and flow rate: CF4, 50 sccm; working pressure: 1.0 Pa; plasma power: radio frequency (RF) power supply, 200 W; temperature: 100°C.

[0099] The main product parameters of various gas diffusion electrodes are listed below.

[0100]

[0101] 2. The anion exchange membrane (AEM) used in the membrane electrode is surface modified. The modification method is based on reactive ion etching (RIE) technology to perform physicochemical synergistic modification of the surface. The specific steps are as follows: (1) Surface cleaning and pretreatment: The anion exchange membrane was cut to a predetermined size (5 cm × 5 cm) and ultrasonically cleaned in deionized water and anhydrous ethanol for 15 minutes each time to thoroughly remove adsorbed pollutants from the surface. The membrane was then dried in a vacuum drying oven at 40-60℃ for 3 hours to ensure that the membrane surface was clean and the moisture content was within a controllable range.

[0102] (2) Reactive ion etching: The dried AEM is flattened and fixed on the sample stage of the reactive ion etching machine to avoid surface wrinkles. The etching gas can be oxygen (O2), argon (Ar) or a mixture of the two; the mixing volume ratio is O2:Ar = 1:4, and the total gas flow rate is controlled at 100 sccm. The radio frequency power is set to 200 W, and the chamber pressure is maintained at 27 Pa.

[0103] The main parameters of various anion exchange membranes are listed below.

[0104]

[0105] 3. The selection of gas diffusion electrodes and anion exchange membranes used in membrane electrodes is listed below.

[0106]

[0107] Example 1: Morphology of the gas diffusion electrode and anion exchange membrane

[0108] I. Test objects: Gas diffusion electrodes and anion exchange membranes involved in each embodiment and comparative example.

[0109] II. Testing Method: SEM images were obtained using methods commonly used in this field.

[0110] III. Test Results: 1. Morphology of the gas diffusion electrode (1) Etched gas diffusion electrode ②, such as Figures 1 to 3 As shown, after etching, the Ag catalyst layer is uniformly coated on the carbon surface, forming a continuous porous and regularly arranged particle loading morphology, which is beneficial to gas-liquid transport and interfacial mass transfer.

[0111] (2) Unetched gas diffusion electrode ②, such as Figure 4 As shown, the surface of the Ag catalyst layer is smooth after etching, which has limited impact on gas-liquid transport and interfacial mass transfer.

[0112] (3) Etched gas diffusion electrode ④, such as Figure 5 and Figure 6 As shown, after etching, the Ag catalyst layer is uniformly coated on the carbon surface, forming a continuous porous and regularly arranged particle loading morphology, which is beneficial to gas-liquid transport and interfacial mass transfer.

[0113] 2. Appearance and morphology of anion exchange membranes

[0114] (1) The etched anion exchange membrane ①, such as Figure 7 As shown, through the synergistic effect of ion bombardment and chemical reaction, a nanoscale rough structure can be constructed on the membrane surface, and oxygen-containing polar functional groups can be introduced, thereby improving the surface hydrophilicity.

[0115] (2) Unetched anion exchange membrane ①, such as Figure 8 As shown, no nanoscale rough structure was constructed.

[0116] Example 2: Performance Test of Carbon Dioxide Electrocatalytic Reduction

[0117] I. Test Object: Electrolytic cells assembled from the membrane electrodes of each embodiment and comparative example, reflecting the performance of the membrane electrodes therein.

[0118] II. Testing Methods: 1. Assembly of the electrolytic cell, as detailed below: (1) Cathode region of the electrolytic cell: The membrane electrode of each embodiment and comparative example is used. In the electrolytic cell, the effective area of ​​the membrane electrode is strictly limited to 5 cm × 5 cm.

[0119] (2) Anode zone of the electrolytic cell: The anode catalyst used is prepared by attaching iridium to a platinum-plated titanium felt through a spraying process, including the following steps: S1. Slurry preparation steps: Weigh 100 mg of iridium black (Ir black, purity 80%) as a catalyst according to the proportion, and add 4 mL of deionized water, 6 mL of ethanol, 20 mL of isopropanol and 0.4 mL of D520 dispersant (concentration 5wt%) in sequence. Place the mixture in an ultrasonic device and ultrasonically treat it at 10℃ for 1 hour to fully disperse the components and form a uniform slurry.

[0120] S2. Homogenization process: Transfer the ultrasonicated slurry to a high-speed homogenizer and homogenize it at the set speed. Repeat the operation 5 times, with a homogenization angle of 10° each time, to ensure that the slurry particles are further refined and its dispersion stability is improved.

[0121] S3. Spray Coating Step: The homogenized slurry is loaded into the spray coating equipment and uniformly coated onto the pre-set substrate surface using conventional spray coating technology. Spray parameters are controlled until the slurry is completely coated, forming a catalyst layer with a regular structure. Figure 9 .

[0122] S4. Catalyst Loading Measurement and Equipment Cleaning Procedure: After spraying, use an HRF handheld detector to measure the catalyst loading of the coating – it should be 0.2 mg / cm³. 2 Subsequently, anhydrous ethanol was used to thoroughly clean the inside of the spraying equipment to remove residual slurry, ensuring that the subsequent preparation process was not contaminated, and obtaining titanium felt coated with iridium.

[0123] (3) Electrolytic cell assembly steps: In the electrolytic cell assembly process, the assembly sequence of each component follows specific specifications: First, place the titanium felt coated with iridium, then sequentially lay the PTFE sealing frame membrane matching the thickness of the titanium felt, the etched anion exchange membrane, the PTFE sealing frame membrane matching the thickness of the gas diffusion electrode, and the gas diffusion electrode (etched cathode catalyst layer and gas diffusion layer), such as... Figure 10 After etching and modification, the cathode catalyst layer yields a superhydrophobic rough surface, which increases active sites and suppresses side reactions. Similarly, after etching and modification, the anion exchange membrane yields an ordered nanoarray, increasing the electrochemical three-phase reaction area, enhancing hydrophilicity, constructing ordered transport channels, increasing the area, and improving OH- ion exchange capacity. - Mass transfer efficiency.

[0124] Finally, a torque wrench is used to tightly compress the flow channel plates on both sides to ensure the stability of the entire structure. The slotting torque must be strictly controlled at 4 N·m.

[0125] 2. The electrolytic cell was tested, as follows: An electric current was applied to the electrolytic cell; electrolyte was introduced into the anode region; and CO2 was introduced into the cathode region. The temperature parameters during the test were set at approximately 40℃. Regarding the control of gas and electrolyte flow rates, the CO2 gas flow rate in the cathode region was maintained at 200 sccm, and the electrolyte in the anode region was 1 M KOH, with a flow rate controlled at 50 ml / min. To facilitate real-time monitoring of gas composition changes, the gas outlet pipe in the cathode region was directly connected to a gas chromatograph, and the gas chromatography test operation was strictly performed according to the established standard test methods.

[0126] The Faraday efficiency (FE) of CO is calculated using the following formula:

[0127] In the formula: n This indicates the number of electrons transferred; for the reduction of CO2 to CO, this value is 2. p 0 represents standard atmospheric pressure, or 101 kPa. v This indicates the gas flow rate of the gaseous products detected by gas chromatography. x i This indicates the mole fraction of CO in the gaseous products detected by gas chromatography. F The value is Faraday's constant, 96485 C·mol⁻¹. -1 ; I This represents current density, mA·cm. -2 ; R The ideal gas constant is 8.314 J·mol⁻¹. -1 ·K -1 ; T K represents absolute temperature.

[0128] III. Test Results: The following test results are current values ​​read after the voltage reaches the set value and no significant decay occurs within 5 minutes. Higher Faraday efficiency (FE), higher current density, and lower voltage indicate better electrolytic performance. In engineering operation, a higher FE (CO) and higher current density are typically required at a voltage of 2.8-3 V for better electrolytic performance.

[0129] 1. Electrolytic cell assembled using the membrane electrode of Example 1

[0130] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0131]

[0132] 2. Electrolytic cell assembled using the membrane electrode of Example 2

[0133] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0134]

[0135] 3. Electrolytic cell assembled using the membrane electrode of Example 3

[0136] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0137]

[0138] (2) The measured voltage and Faraday efficiency FE(CO) stability test results are as follows (constant current 200 mA / cm²). 2 ).

[0139]

[0140] 4. Electrolytic cell assembled using the membrane electrode of Example 4

[0141] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0142]

[0143] 5. Electrolytic cell assembled using the membrane electrode of Example 5

[0144] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0145]

[0146] 6. Electrolytic cell assembled using the membrane electrode of Example 6

[0147] 7. Electrolytic cell assembled using the membrane electrode assembly of Comparative Example 1

[0148] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0149]

[0150] 8. Electrolyzer assembled using the membrane electrode assembly of Comparative Example 2

[0151] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0152]

[0153] 9. An electrolytic cell assembled using the membrane electrode assembly of Comparative Example 3

[0154] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0155]

[0156] 10. An electrolytic cell assembled using the membrane electrode assembly of Comparative Example 4

[0157] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0158]

[0159] 11. An electrolytic cell assembled using the membrane electrode assembly of Comparative Example 5

[0160] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0161]

[0162] 12. An electrolytic cell assembled using the membrane electrode assembly of Comparative Example 6

[0163] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0164]

[0165] 13. An electrolytic cell assembled using the membrane electrode assembly of Comparative Example 7

[0166] (1) The measured current density and Faraday efficiency FE(CO) are shown in the table below.

[0167]

[0168] During the test, the mechanical strength of the membrane electrode will decrease, and structural collapse will occur during electrolysis at 3 V or above, leading to hydrogen evolution reaction. The overall Faraday efficiency FE(CO) is measured to be less than 50%.

[0169] In summary, this invention utilizes magnetron sputtering and plasma etching techniques to construct an ordered nano-silver catalytic layer on the surface of a gas diffusion electrode. By controlling the sputtering thickness, the silver loading can be precisely adjusted, and the structural characteristics and electrochemical performance of the gas diffusion electrode are further systematically investigated. Ag-GDEs constructed based on TGPH060 or XGL-R-055 carbon paper can achieve approximately 90% CO selectivity in membrane electrodes.

[0170] Therefore, the construction of the ordered nano-silver catalytic layer in this invention not only provides abundant active sites and enhances the adsorption and activation of reactants, but also optimizes the reaction energy barrier through unique electronic structure, which helps to improve CO selectivity.

[0171] Performance tests on the electrolyzer showed that the electrolyzer assembled using the membrane electrode from Example 3 performed well at 200 mA / cm². 2 At current density, the cell voltage is only 3.17 V, CO selectivity exceeds 85%, and it has excellent stability, capable of stable operation for over 120 hours, meeting the requirements of industrial-grade electrolysis.

[0172] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing a CO2RR film electrode in an AEM system, characterized in that, The membrane electrode comprises a gas diffusion layer, an etched cathode catalyst layer, and an etched anion exchange membrane sequentially arranged; the preparation method includes the following steps: S1. A catalyst is deposited on one side of the gas diffusion layer relative to the etched anion exchange membrane, and a cathode catalyst layer is formed on one side of the gas diffusion layer. S2. The surface of the cathode catalyst layer is etched using CF4 plasma to form the etched cathode catalyst layer; the total amount of CF4 gas used in the etching is 10-250 scc. S3. An anion exchange membrane is provided on the surface of the etched cathode catalyst layer. The surface of the anion exchange membrane is etched using plasma containing O2 to form the etched anion exchange membrane. The total amount of etching gas used is 10-300 scc.

2. The method for preparing the CO2RR film electrode of the AEM system according to claim 1, characterized in that, In step S2, the total amount of CF4 gas used for etching is 100-250 scc, for example 125 scc; In step S2, the CF4 gas flow rate used for etching is preferably 20-50 sccm; In step S2, the etching time is preferably 30-300 s, more preferably 100-300 s, for example 150 s.

3. The method for preparing the CO2RR film electrode of the AEM system according to claim 1 or 2, characterized in that, The surface contact angle of the etched cathode catalyst layer is 120°-160°, preferably 127°-155°, for example 128°, 135°, 137°, 140°, 145° or 155°; And / or, the surface contact angle of the etched anion exchange membrane is 50°-65°, for example, 60°.

4. The method for preparing the CO2RR film electrode of the AEM system according to claim 1, characterized in that, In step S2, one or more of the following conditions must be met: (1) The radio frequency power of the etching is 50-200 W; (2) The etching temperature is 20-100℃; and, (3) The etching working pressure is 0.5-2 Pa, for example 1 Pa.

5. The method for preparing the CO2RR film electrode of the AEM system according to claim 1, characterized in that, In step S1, one or more of the following conditions must be met: (1) A hydrophobic layer is provided on the side of the gas diffusion layer adjacent to the etched cathode catalyst layer; (2) The porosity of the gas diffusion layer is 30%-80%, for example 50%-78%; and, (3) The thickness of the cathode catalyst layer is 100-200 nm, for example 150 nm.

6. The method for preparing the CO2RR film electrode of the AEM system according to claim 1, characterized in that, In step S3, the total amount of etching gas used is 100-200 scc, for example 166.7 scc; In step S3, the total gas flow rate for etching is preferably 20-100 sccm; In step S3, the etching time is preferably 30-300 s, for example 100-200 s.

7. The method for preparing the CO2RR film electrode of the AEM system according to claim 6, characterized in that, Step S3 also includes satisfying one or more of the following conditions: (1) The etching atmosphere is O2 and Ar; the volume ratio of O2 to Ar is preferably 1: (1-4); (2) The etching working pressure is 5-50 Pa, for example 27 Pa; and, (3) The radio frequency power of the etching is 50-200 W.

8. The method for preparing the CO2RR film electrode of the AEM system according to claim 1, characterized in that, In step S1, one or more of the following conditions must be met: (1) The active component of the cathode catalyst layer is a noble metal; preferably, the noble metal is Ag; (2) the areal density of the cathode catalyst layer is 0.15 to 0.3 mg / cm 2 , for example 0.17 to 0.28 mg / cm 2 ; (3) The porosity of the cathode catalyst layer is 50%-80%; (4) The bonding force between the cathode catalyst layer and the gas diffusion layer is 30-40 MPa, for example 32 MPa, 33 MPa, 35 MPa, 36 MPa, 37 MPa or 38 MPa; (5) The surface contact angle of the cathode catalyst layer is 90°-100°, for example 93°, 95°, 97° or 100°; and, (6) The cathode catalyst layer is formed on the gas diffusion layer by physical vapor deposition.

9. The method for preparing the CO2RR film electrode of the AEM system according to claim 8, characterized in that, In step S1, one or more of the following conditions must be met: (1) The physical vapor deposition method is magnetron sputtering; (2) The temperature of the physical vapor deposition is 0-100℃; (3) The atmosphere for physical vapor deposition is an inert atmosphere, such as an argon atmosphere; (4) The working pressure of the physical vapor deposition is 0.2-0.3 Pa; and, (5) The physical vapor deposition time is 150-300 s, for example 200 s.

10. A CO2RR membrane electrode of an AEM system prepared by any one of claims 1-9.

Images