A gas diffusion electrode based on polytetrafluoroethylene film and a preparation method and application of low temperature and large area

Abstract

The application provides a gas diffusion electrode based on a polytetrafluoroethylene film and a preparation method and application of the gas diffusion electrode with low temperature and large area. The preparation method comprises the following steps: coating a noble metal salt on the surface of a polytetrafluoroethylene film, placing the polytetrafluoroethylene film in a first reducing agent solution, performing first soaking to obtain a noble metal loaded polytetrafluoroethylene film; placing the noble metal loaded polytetrafluoroethylene film in a copper salt solution, performing second soaking, adding a second reducing agent solution into the copper salt solution, and forming a copper plating layer on the surface of the noble metal loaded polytetrafluoroethylene; and setting a catalyst layer on the surface of the copper plating layer far away from the polytetrafluoroethylene film to obtain the gas diffusion electrode based on the polytetrafluoroethylene film. The application uses a hydrophobic polytetrafluoroethylene film as a carrier, and a large-area copper plating layer gas diffusion electrode with good uniformity and conductivity is prepared at a lower temperature, the electrocatalytic CO2 reduction conversion activity is high, the selectivity of C 2+ products such as ethylene and ethanol is high, and the stability is good.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to electrocatalytic CO2 reduction and conversion reactions, and more particularly to a gas diffusion electrode based on a polytetrafluoroethylene membrane and its low-temperature, large-area preparation method and application. Background Technology

[0002] Electrocatalytic CO2 reduction technology is an important pathway to convert CO2 into high-value-added chemicals (such as CO, formic acid, ethylene, ethanol, propanol, etc.), contributing to carbon cycling and mitigating the greenhouse effect. In this technology, the gas diffusion electrode (GDE) is a key component. Its porous structure enables efficient CO2 mass transfer and provides electron conduction channels; simultaneously, it regulates the local reaction environment at the gas-liquid-solid three-phase interface, thereby improving the reaction rate and CO2 utilization efficiency. The fabrication of the gas diffusion electrode mainly involves the selection of the substrate material (such as carbon paper, carbon cloth, or metal materials) and precise control of the fabrication process (such as coating, physical / chemical vapor deposition, and electrochemical deposition). Surface treatment is also required to optimize the gas and liquid transport properties. However, high-quality carbon materials have complex fabrication processes, are prone to wetting, and have poor durability; metal materials require expensive processes such as physical / chemical vapor deposition and electrochemical deposition, as well as precise control conditions, increasing the fabrication difficulty and production cost. Furthermore, the substrate layer faces challenges such as poor durability, limited mass transfer, insufficient mechanical strength, and inconsistent surface treatment, restricting its large-scale application.

[0003] CN115821306A discloses an Ag-supported self-supporting carbon membrane with strong mechanical stability and numerous catalytic active sites, which can effectively improve the electrocatalytic CO2 reduction efficiency. After hydrophobic treatment, this Ag-supported self-supporting carbon membrane can be directly used as a gas diffusion electrode for electrocatalytic CO2 reduction, solving the problem of limited application of powdered silver-based catalysts in the prior art. Performance testing using a flow cell system shows that when used as a gas diffusion electrode, this catalyst can achieve a higher current density at a higher Faradaic efficiency and has the ability to operate stably for a long time. Furthermore, the electrode material is more convenient to recover after a long-term electrocatalytic CO2 reduction reaction.

[0004] CN119615227A discloses a flow-through gas diffusion electrode, prepared by the following method: N-methyl-2-pyrrolidone is added to polyacetylimide and subjected to ultrasonic treatment; copper powder is added to a transparent and homogeneous mixed solution of N-methyl-2-pyrrolidone and polyacetylimide and magnetically stirred; a homogeneous mixture of N-methyl-2-pyrrolidone, polyacetylimide, and copper powder, along with hollow fibers of polyacetylimide and copper powder, are calcined in a furnace to obtain the flow-through gas diffusion electrode. This invention employs a flow-through gas diffusion electrode with the above structure for electrochemical CO2 reduction, ensuring efficient carbon dioxide transport and utilization, and improving the efficiency of the electrochemical reduction reaction.

[0005] CN108842162A discloses a SnO2 nanosheet gas diffusion electrode and method for electrochemical reduction of CO2. The SnO2 nanosheet catalytic layer electrode is bonded to the carbon powder-coated side of the gas diffusion electrode, and then subjected to high-temperature hot pressing to form the SnO2 nanosheet gas diffusion electrode. The catalytic layer of this electrode has a sheet-like structure with a well-developed pore structure, which can effectively provide channels for the transport of substances, enhance electron transport, improve conductivity, and has good application prospects.

[0006] Therefore, it is of great significance to provide a gas diffusion electrode with excellent performance, simple preparation process, mild reaction conditions, and large-area preparation, as well as its preparation method. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane, along with its low-temperature, large-area preparation method and applications. This invention uses a hydrophobic, porous PTFE membrane as a carrier to prepare a copper-plated gas diffusion electrode with good uniformity and high conductivity at a relatively low temperature. Further, a catalyst layer is added, resulting in a PTFE membrane-based gas diffusion electrode with high electrocatalytic activity for CO2 reduction and conversion, and high electrocatalytic activity for CO2 reduction and conversion of ethylene, ethanol, and other C2Cs. 2+ The product exhibits high selectivity and good stability. The preparation method provided by this invention is simple to operate, requires no complex equipment, has mild reaction conditions, and is easy to scale up to a large area. It can uniformly load highly conductive copper plating and catalyst layers onto large-sized hydrophobic polytetrafluoroethylene films (10cm × 10cm and above), demonstrating potential for industrial application.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a low-temperature, large-area preparation method for a gas diffusion electrode based on a polytetrafluoroethylene film, the preparation method comprising:

[0010] A noble metal salt is coated on the surface of a polytetrafluoroethylene (PTFE) membrane, which is then immersed in a first reducing agent solution to obtain a noble metal-loaded PTFE membrane. The noble metal-loaded PTFE membrane is then immersed in a copper salt solution for a second immersion, while a second reducing agent solution is added to the copper salt solution to form a copper plating layer on the surface of the noble metal-loaded PTFE membrane. A catalyst layer is then deposited on the side of the copper plating layer away from the PTFE membrane to obtain the gas diffusion electrode based on the PTFE membrane.

[0011] In this invention, "low temperature" refers to a temperature below 100°C, and "large area" refers to a copper plating layer with an area of ​​15 cm² on the surface of the polytetrafluoroethylene film. 2 above.

[0012] This invention utilizes a hydrophobic and porous polytetrafluoroethylene (PTFE) membrane as a carrier, which facilitates gas transport while reducing wettability. In a solution environment, based on a chemical copper plating method, a noble metal is first loaded onto the PTFE membrane surface as an active site to induce uniform deposition of a copper layer. A uniform and highly conductive copper plating layer is then prepared on the hydrophobic PTFE membrane, resulting in a gas diffusion electrode substrate with good compatibility with the electrocatalytic CO2 reduction catalyst. Further addition of a catalyst layer results in a gas diffusion electrode exhibiting good gas diffusion, electron transport, and hydrophobicity, as well as high electrocatalytic CO2 reduction conversion activity, and high efficiency for CO2 reduction of ethylene and ethanol. 2+ The product exhibits high selectivity and good stability.

[0013] The preparation method provided by this invention is simple to operate, has mild reaction conditions, does not require complex equipment or harsh process conditions such as high temperature, does not easily damage the polytetrafluoroethylene membrane structure, and can be easily prepared on a large area. It can uniformly load a highly conductive copper plating layer and catalyst layer on a large-size hydrophobic polytetrafluoroethylene membrane of 10cm×10cm or larger, and has the potential for industrial application.

[0014] Preferably, the noble metal salt includes any one or a combination of at least two of AuCl3, AgNO3, AgCl, PtCl4, H2PtCl6, PdCl2 or Pd(NO3)2.

[0015] Preferably, the loading of noble metal in the noble metal-loaded polytetrafluoroethylene membrane is 1 μg / cm³. 2 ~5μg / cm 2 .

[0016] Preferably, the first reducing agent in the first reducing agent solution includes any one of sodium borohydride, lithium aluminum hydride, sodium cyanoborohydride, or sodium aminoborohydride.

[0017] Preferably, the concentration of the first reducing agent in the first reducing agent solution is 0.05 g / L to 0.5 g / L.

[0018] Preferably, the second reducing agent in the second reducing agent solution includes formaldehyde and / or hydrazine.

[0019] Preferably, the concentration of the second reducing agent in the second reducing agent solution is 0.1 mol / L to 1.0 mol / L.

[0020] Preferably, the copper salt in the copper salt solution includes copper nitrate and / or copper sulfate.

[0021] Preferably, the copper salt solution further includes disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate.

[0022] Preferably, the solvent for the copper salt solution includes a mixture of water and ethanol.

[0023] Preferably, the concentration of copper ions in the copper salt solution is 0.1 mol / L to 0.5 mol / L.

[0024] Preferably, the total concentration of disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate in the copper salt solution is 0.15 mol / L to 0.6 mol / L.

[0025] Preferably, in the mixed solution, the volume ratio of water to ethanol is (1~5):1.

[0026] Preferably, the first soaking time is 15 min to 30 min.

[0027] Preferably, the second soaking time is 3 min to 60 min.

[0028] Preferably, during the second soaking process, the temperature of the copper salt solution is 60°C to 80°C.

[0029] Preferably, during the second soaking process, the pH of the copper salt solution is adjusted to 12-13 using sodium hydroxide / potassium hydroxide.

[0030] Preferably, the thickness of the copper plating layer is 20μm to 500μm.

[0031] Preferably, the voltage for the electropolishing treatment is 2V~6V vs. RHE.

[0032] Preferably, the polishing time is 5s to 100s.

[0033] Preferably, the catalyst layer is formed by loading a powdered catalyst onto the surface of a copper plating layer to obtain a powdered catalyst layer; the loading amount of the powdered catalyst is 0.5 mg / cm³. 2~5mg / cm 2 .

[0034] In this invention, because the copper plating layer has good uniformity and high conductivity, it can support any catalyst for electrocatalytic CO2 reduction and conversion reaction, thus having universality.

[0035] In this invention, the method of loading the powder catalyst on the copper plating surface includes dispersing the powder catalyst in Nafion solution, methanol / ethanol / isopropanol and aqueous solution, and then loading it onto the copper plating surface by drop coating, suspension coating and spray coating, etc., and drying at room temperature to obtain a gas diffusion electrode based on polytetrafluoroethylene film loaded with powder catalyst layer.

[0036] Preferably, the catalyst layer is configured by: electropolishing the surface of the copper plating layer away from the polytetrafluoroethylene film, and then electro-oxidizing the electropolished copper plating layer in situ to obtain a copper oxide catalyst layer; the thickness of the copper oxide catalyst layer is 2μm~15μm.

[0037] The preparation method provided by this invention can also directly perform in-situ electro-oxidation on the polished copper plating layer, obtaining a catalytically active copper oxide catalyst layer. This method eliminates the need for complex equipment and additional catalyst loading, enabling the production of a gas diffusion electrode for electrocatalytic CO2 reduction and conversion reactions. Furthermore, the electrode exhibits good conductivity, facilitating electron transport. The copper oxide layer, acting as a catalyst, is uniformly distributed, resulting in high electrocatalytic CO2 reduction and conversion activity, particularly for C-type reactions such as ethylene and ethanol. 2+ The product has high selectivity and the material has good stability.

[0038] Preferably, the voltage of the electro-oxidation treatment is 0.5V~1V vs. RHE.

[0039] Preferably, the electro-oxidation treatment time is 100s to 800s.

[0040] In a second aspect, the present invention provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane, wherein the gas diffusion electrode based on the PTFE membrane is prepared by the preparation method described in the first aspect; the gas diffusion electrode based on the PTFE membrane comprises a PTFE membrane, a copper plating layer and a catalyst layer stacked sequentially.

[0041] Thirdly, the present invention provides an application of a gas diffusion electrode based on a polytetrafluoroethylene membrane as described in the first aspect, wherein the gas diffusion electrode based on the polytetrafluoroethylene membrane serves as a cathode and is applied to an electrocatalytic CO2 reduction and conversion reaction.

[0042] In this invention, the terms "first aspect," "second aspect," "third aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) This invention uses a hydrophobic and porous polytetrafluoroethylene (PTFE) membrane as a carrier to prepare a copper-plated gas diffusion electrode with good uniformity and high conductivity at a relatively low temperature. Further, a catalyst layer is added, resulting in a PTFE-based gas diffusion electrode with high electrocatalytic CO2 reduction and conversion activity, and high CO2 reduction and conversion activity for ethylene, ethanol, and other C... 2+ The product exhibits high selectivity and good stability.

[0045] (2) The preparation method provided by the present invention is simple to operate, requires no complicated equipment, and has mild reaction conditions. It can load a copper plating layer and a catalyst layer with good uniformity and high conductivity on a large-size hydrophobic polytetrafluoroethylene film of 10cm×10cm or more, and has the potential for industrial application. Attached Figure Description

[0046] Figure 1 It is the large-size (10cm×10cm) copper plating layer prepared on a tetrafluoroethylene film as provided in Example 2.

[0047] Figure 2 The linear current-voltage (LSV) curve of the gas diffusion electrode provided in Example 2 is shown.

[0048] Figure 3 The voltage-time (Ut) stability curve of the gas diffusion electrode provided in Example 2 under a constant current of -400mA is shown.

[0049] Figure 4 This is a yield diagram of CO2 reduction products from the gas diffusion electrode provided in Example 2.

[0050] Figure 5 This is the Faraday efficiency diagram of the gas diffusion electrode provided in Example 2. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. In this invention, "a combination of at least two" means, unless otherwise specified, a quantity greater than or equal to two. For example, "any combination of one or at least two" means one or more of two. It is understood that when referring to "a combination of at least two," it means any suitable combination of multiple items, i.e., a combination of "at least two" items carried out in a manner that does not conflict with and allows for the implementation of the invention.

[0053] In the description of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0054] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0055] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0056] In one specific embodiment, the present invention provides a method for preparing a gas diffusion electrode based on a polytetrafluoroethylene film, the method comprising:

[0057] A noble metal salt is coated on the surface of a polytetrafluoroethylene (PTFE) membrane, which is then immersed in a first reducing agent solution to obtain a noble metal-loaded PTFE membrane. The noble metal-loaded PTFE membrane is then immersed in a copper salt solution for a second immersion, while a second reducing agent solution is added to the copper salt solution to form a copper plating layer on the surface of the noble metal-loaded PTFE membrane. A catalyst layer is then deposited on the side of the copper plating layer away from the PTFE membrane to obtain the gas diffusion electrode based on the PTFE membrane.

[0058] This invention utilizes a hydrophobic and porous polytetrafluoroethylene (PTFE) membrane as a carrier, which facilitates gas transport while reducing wettability. In a solution environment, based on a chemical copper plating method, a noble metal is first loaded onto the surface of the PTFE membrane, serving as an active site to induce uniform deposition of a copper layer. A uniform and highly conductive copper plating layer is then prepared on the hydrophobic PTFE membrane, resulting in a gas diffusion electrode substrate with good compatibility with the electrocatalytic CO2 reduction catalyst. Further addition of a catalyst layer results in a gas diffusion electrode exhibiting good gas diffusion, electron transport, and hydrophobicity, as well as high electrocatalytic CO2 reduction conversion activity, and high efficiency for CO2 reduction of ethylene and ethanol. 2+ The product exhibits high selectivity and good stability.

[0059] The preparation method provided by this invention is simple to operate, has mild reaction conditions, does not require complex equipment or harsh process conditions such as high temperature, and is not easily damaged by the polytetrafluoroethylene membrane structure. It can uniformly load a copper plating layer and a catalyst layer with good uniformity and high conductivity on a large-size hydrophobic polytetrafluoroethylene membrane of 10cm×10cm or larger, and has the potential for industrial application.

[0060] In some embodiments, the noble metal salt includes any one or a combination of at least two of AuCl3, AgNO3, AgCl, PtCl4, H2PtCl6, PdCl2, or Pd(NO3)2. Typical but non-limiting combinations include combinations of AuCl3 and AgNO3, AgCl and PtCl4, H2PtCl6 and PdCl2, or Pd(NO3)2 and AuCl3.

[0061] In some embodiments, the loading of noble metal in the noble metal-loaded polytetrafluoroethylene membrane is 1 μg / cm³. 2 ~5μg / cm 2 For example, it could be 1 μg / cm 2 2μg / cm 2 3μg / cm 24μg / cm 2 or 5μg / cm 2 .

[0062] In some embodiments, the first reducing agent in the first reducing agent solution includes any one of sodium borohydride, lithium aluminum hydride, sodium cyanoborohydride, or sodium aminoborohydride.

[0063] In some embodiments, the solvent of the first reducing agent solution includes water.

[0064] In some embodiments, the concentration of the first reducing agent in the first reducing agent solution is 0.05 g / L to 0.5 g / L, for example, it can be 0.05 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.35 g / L, 0.4 g / L, 0.45 g / L or 0.5 g / L.

[0065] In some embodiments, the second reducing agent in the second reducing agent solution includes formaldehyde and / or hydrazine.

[0066] In some embodiments, the concentration of the second reducing agent in the second reducing agent solution is 0.1 mol / L to 1.0 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0067] In some embodiments, the copper salt in the copper salt solution includes copper nitrate and / or copper sulfate.

[0068] In some embodiments, the copper salt solution further includes disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate.

[0069] In some embodiments, the solvent for the copper salt solution includes a mixture of water and ethanol.

[0070] In some embodiments, the concentration of copper ions in the copper salt solution is 0.1 mol / L to 0.5 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L.

[0071] In some embodiments, the total concentration of disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate in the copper salt solution is 0.15 mol / L to 0.6 mol / L, for example, it can be 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, or 0.6 mol / L.

[0072] In some embodiments, the volume ratio of water to ethanol in the mixed solution is (1~5):1, for example, it can be 1:1, 2:1, 3:1, 4:1 or 5:1.

[0073] In some embodiments, the first soaking time is 15 min to 30 min, for example, it can be 15 min, 18 min, 20 min, 22 min, 25 min, 27 min or 30 min.

[0074] In some embodiments, the second soaking time is 3 min to 60 min, for example, it can be 3 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0075] In some embodiments, during the second soaking process, the temperature of the copper salt solution is 60°C to 80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C.

[0076] In some embodiments, during the second soaking process, the pH of the copper salt solution is adjusted to 12-13 using sodium hydroxide / potassium hydroxide, for example, 12, 12.5 or 13.

[0077] In some embodiments, the thickness of the copper plating layer is 20μm to 500μm, for example, it can be 20μm, 50μm, 100μm, 200μm, 300μm, 400μm or 500μm.

[0078] In some embodiments, the voltage of the electropolishing treatment is 2V~6V vs. RHE, for example, it can be 2V, 3V, 4V, 5V or 6V.

[0079] In some embodiments, the polishing time is 5s to 100s, for example, it can be 5s, 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s or 100s.

[0080] In some embodiments, the catalyst layer is formed by loading a powdered catalyst onto the surface of a copper plating layer to obtain a powdered catalyst layer; the loading amount of the powdered catalyst is 0.5 mg / cm³.2 ~5mg / cm 2 .

[0081] In this invention, the copper plating layer possesses excellent uniformity and high conductivity, enabling the loading of any catalyst for electrocatalytic CO2 reduction and conversion reactions, thus exhibiting versatility. When the catalyst layer is configured by loading a powdered catalyst onto the surface of the copper plating layer to obtain a powdered catalyst layer, the thickness of the copper plating layer is preferably 20 μm to 50 μm.

[0082] In this invention, the method of loading the powder catalyst on the copper plating surface includes dispersing the powder catalyst in Nafion solution, methanol / ethanol / isopropanol and aqueous solution, and then loading it onto the copper plating surface by drop coating, suspension coating and spray coating, etc., and drying at room temperature to obtain a gas diffusion electrode based on polytetrafluoroethylene film loaded with powder catalyst layer.

[0083] In some embodiments, the catalyst layer is configured by: electropolishing the surface of the copper plating layer away from the polytetrafluoroethylene film, and then performing in-situ electro-oxidation on the electropolished copper plating layer to obtain a copper oxide catalyst layer; the thickness of the copper oxide catalyst layer is 2μm to 15μm, for example, it can be 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 13μm or 15μm.

[0084] The preparation method provided by this invention can directly perform in-situ electro-oxidation on the polished copper plating layer, obtaining a catalytically active copper oxide catalyst layer. This method eliminates the need for complex equipment and additional catalyst loading, enabling the production of a gas diffusion electrode for electrocatalytic CO2 reduction and conversion reactions. Furthermore, the electrode exhibits good conductivity, facilitating electron transport. The copper oxide layer, acting as a catalyst, is uniformly distributed, resulting in high electrocatalytic CO2 reduction and conversion activity, particularly for C-type reactions such as ethylene and ethanol. 2+ The product exhibits high selectivity and good material stability. When the catalyst layer is prepared by in-situ electro-oxidation of the polished copper plating to obtain a copper oxide catalyst layer, the thickness of the copper plating is preferably 50 μm to 500 μm.

[0085] In some embodiments, the voltage of the electro-oxidation treatment is 0.5V to 1V vs. RHE, for example, it can be 0.5V, 0.55V, 0.6V, 0.65V, 0.7V, 0.75V, 0.8V, 0.85V, 0.9V or 1V.

[0086] In some embodiments, the electro-oxidation treatment time is 100s to 800s, for example, it can be 100s, 200s, 300s, 400s, 500s, 600s, 700s or 800s.

[0087] In another specific embodiment, the present invention provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane, which is prepared by the preparation method described in the preceding specific embodiment; the gas diffusion electrode based on the PTFE membrane comprises a PTFE membrane, a copper plating layer, and a catalyst layer stacked sequentially.

[0088] In yet another embodiment, the present invention provides an application of a gas diffusion electrode based on a polytetrafluoroethylene membrane as described in another embodiment above, wherein the gas diffusion electrode based on the polytetrafluoroethylene membrane serves as a cathode and is applied to an electrocatalytic CO2 reduction and conversion reaction.

[0089] In this invention, the electrocatalytic CO2 reduction and conversion reaction process includes:

[0090] The anode and cathode are placed in an electrochemical reactor. Inert gases (such as argon, nitrogen, and helium) are used to purge the air from the electrolyte. CO2 gas is introduced into the cathode. Under the control of an electrochemical workstation, CO2 reduction and conversion reactions occur under different current (-1mA to -1000mA) or different voltage conditions (0 to -10V vs. RHE) using constant current or constant voltage methods. The reaction products are analyzed online by gas chromatography.

[0091] The inert gas includes argon, nitrogen, and helium, and the flow rate of the inert gas and CO2 is between 20 mL / min and 50 mL / min.

[0092] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0093] Example 1

[0094] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane-based gas diffusion electrode includes a PTFE membrane, a copper plating layer, and a copper oxide catalyst layer stacked sequentially. The thickness of the copper plating layer is 200 μm, and the thickness of the copper oxide catalyst layer is 10 μm.

[0095] The method for preparing the gas diffusion electrode based on polytetrafluoroethylene film includes:

[0096] (1) Preparation of polytetrafluoroethylene membrane supported on noble metal: The loading amount of Pd in ​​PdCl2 on a polytetrafluoroethylene membrane with a size of 4cm*4cm is 3μg / cm 2PdCl2 was coated onto the surface of a polytetrafluoroethylene membrane, and then it was immersed in a sodium borohydride solution with a concentration of 0.3 g / L for 25 min, dried, and cleaned to obtain a Pd-loaded polytetrafluoroethylene membrane.

[0097] (2) Preparation of copper plating layer: In a mixed solution of water and ethanol with a volume ratio of 3:1, a copper ion concentration of 0.2 mol / L and a dipotassium ethylenediaminetetraacetate concentration of 0.3 mol / L were prepared. The pH of the copper salt solution was adjusted to 12.5 with KOH. The copper salt solution was heated to 75°C. The Pd-loaded polytetrafluoroethylene membrane was placed in the copper salt solution. At the same time, a formaldehyde solution with a concentration of 0.2 mol / L was added to the copper salt solution. The membrane was soaked for 10 min to form a copper plating layer on the surface of the noble metal-loaded polytetrafluoroethylene membrane.

[0098] (3) Modification of copper oxide catalyst layer: The material is cut and the exposed area of ​​the material is controlled to be 1 cm² using tape. 2 The voltage for electropolishing was set to 4V vs. RHE, and the surface of the copper plating layer away from the polytetrafluoroethylene film was electropolished for 20s. Then, the voltage for electrooxidation was set to 0.75V vs. RHE, and the polished copper plating layer surface was electrooxidized for 400s to form a copper oxide layer, thus obtaining the gas diffusion electrode based on the polytetrafluoroethylene film.

[0099] Example 2

[0100] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane-based gas diffusion electrode includes a PTFE membrane, a copper plating layer, and a copper oxide catalyst layer stacked sequentially. The thickness of the copper plating layer is 85 μm, and the thickness of the copper oxide catalyst layer is 5 μm.

[0101] The method for preparing the gas diffusion electrode based on polytetrafluoroethylene film includes:

[0102] (1) Preparation of noble metal-loaded polytetrafluoroethylene membrane: The loading amount of Au in AuCl3 on a 10cm×10cm polytetrafluoroethylene membrane is 2μg / cm 2 AuCl3 was coated onto the surface of a polytetrafluoroethylene membrane, and then it was immersed in a 0.1 g / L lithium aluminum hydride solution for 20 min, dried, and cleaned to obtain an Au-loaded polytetrafluoroethylene membrane.

[0103] (2) Preparation of copper plating layer: In a mixed solution of water and ethanol with a volume ratio of 4:1, a copper ion concentration of 0.1 mol / L and a total concentration of disodium ethylenediaminetetraacetate of 0.15 mol / L were prepared. The pH of the copper salt solution was adjusted to 12 with NaOH. The copper salt solution was heated to 70°C. The Au-loaded polytetrafluoroethylene membrane was placed in the copper salt solution, and a 0.15 mol / L hydrazine solution was added to the copper salt solution. The membrane was soaked for 10 min, and a copper plating layer was formed on the surface of the Au-loaded polytetrafluoroethylene membrane. The image of the prepared polytetrafluoroethylene membrane with copper plating layer is shown in the figure. Figure 1 As shown.

[0104] (3) Modification of copper oxide catalyst layer: The material is cut and the exposed area of ​​the material is controlled to be 1 cm² using tape. 2 The voltage for electropolishing was set to 2V vs. RHE, and the surface of the copper plating layer away from the polytetrafluoroethylene film was electropolished for 10s. Then, the voltage for electrooxidation was set to 0.5V vs. RHE, and the polished copper plating layer surface was electrooxidized for 300s to form a copper oxide layer, thus obtaining the gas diffusion electrode based on the polytetrafluoroethylene film.

[0105] Example 3

[0106] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane-based gas diffusion electrode includes a PTFE membrane, a copper plating layer, and a copper oxide catalyst layer stacked sequentially. The thickness of the copper plating layer is 400 μm, and the thickness of the copper oxide catalyst layer is 13 μm.

[0107] The method for preparing the gas diffusion electrode based on polytetrafluoroethylene film includes:

[0108] (1) Preparation of noble metal-loaded polytetrafluoroethylene membrane: The loading amount of Ag in AgNO3 on a 4cm*4cm polytetrafluoroethylene membrane is 3μg / cm 2 AgNO3 was coated onto the surface of a polytetrafluoroethylene membrane, and then it was immersed in a sodium cyanoborohydride solution with a concentration of 0.3 g / L for 25 min, dried, and washed to obtain an Ag-loaded polytetrafluoroethylene membrane.

[0109] (2) Preparation of copper plating layer: In a mixed solution of water and ethanol with a volume ratio of 2:1, a copper salt solution with a copper ion concentration of 0.3 mol / L and a total concentration of 0.6 mol / L of disodium ethylenediaminetetraacetate and dipotassium ethylenediaminetetraacetate is prepared. The molar ratio of disodium ethylenediaminetetraacetate to dipotassium ethylenediaminetetraacetate is 1:1. The pH is adjusted to 13 with NaOH. The copper salt solution is heated to 80°C. The Ag-loaded polytetrafluoroethylene membrane is placed in the copper salt solution. At the same time, a formaldehyde solution with a concentration of 0.4 mol / L is added to the copper salt solution. The membrane is soaked for 30 min to form a copper plating layer on the surface of the Ag-loaded polytetrafluoroethylene membrane.

[0110] (3) Modification of copper oxide catalyst layer: The material is cut and the exposed area of ​​the material is controlled to be 1 cm² using tape. 2 The voltage for electropolishing was set to 6V vs. RHE, and the surface of the copper plating layer away from the polytetrafluoroethylene film was electropolished for 50s. Then, the voltage for electrooxidation was set to 0.9V vs. RHE, and the polished copper plating layer surface was electrooxidized for 600s to form a copper oxide layer, thus obtaining the gas diffusion electrode based on the polytetrafluoroethylene film.

[0111] Example 4

[0112] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane-based gas diffusion electrode comprises a PTFE membrane, a copper plating layer, and a MgCu bimetallic catalyst layer stacked sequentially. The copper plating layer has a thickness of 35 μm; the MgCu bimetallic catalyst has a loading of 1 mg / cm³. 2 .

[0113] The method for preparing the gas diffusion electrode based on polytetrafluoroethylene film includes:

[0114] (1) Preparation of polytetrafluoroethylene membrane supported on noble metals: Same as in Example 1;

[0115] (2) Preparation of copper plating layer: Except for the soaking time in copper salt solution of 6 min, the rest is the same as in Example 2.

[0116] (3) Supported powder catalyst: The MgCu bimetallic catalyst prepared by hydrothermal method and Nafion solution are added to the isopropanol aqueous solution. The copper coating surface prepared in step (2) is dried to obtain the gas diffusion electrode based on polytetrafluoroethylene film.

[0117] Example 5

[0118] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene film, which is the same as that in Embodiment 1 except that the thickness of the copper plating layer is 15 μm.

[0119] The preparation method of the gas diffusion electrode based on polytetrafluoroethylene film is the same as that in Example 1, except that in step (2), the Pd-loaded polytetrafluoroethylene film is immersed in copper salt solution for 2 min and the oxidation time is 100 s.

[0120] Example 6

[0121] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene film, which is the same as that in Embodiment 1 except that the thickness of the copper plating layer is 550 μm.

[0122] The preparation method of the gas diffusion electrode based on polytetrafluoroethylene film is the same as that in Example 1, except that the Pd-loaded polytetrafluoroethylene film is immersed in copper salt solution for 65 min in step (2).

[0123] Example 7

[0124] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) film. Except that the temperature of the copper salt solution in step (2) of the preparation process of the gas diffusion electrode based on the PTFE film is 55°C, and the thickness of the copper plating layer in the prepared gas diffusion electrode is 10 μm and the oxidation time is 100 s, the rest are the same as in Example 1.

[0125] Example 8

[0126] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) film. Except that the temperature of the copper salt solution in step (2) of the preparation process of the gas diffusion electrode based on the PTFE film is 85°C and the thickness of the copper plating layer in the prepared gas diffusion electrode is 400 μm, the rest are the same as in Example 1.

[0127] Example 9

[0128] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. Except that in the preparation process of the gas diffusion electrode based on the PTFE membrane, the concentration of copper ions in the copper salt solution in step (2) is 0.08 mol / L, and the thickness of the copper plating layer in the prepared gas diffusion electrode is 20 μm and the oxidation time is 100 s, the rest are the same as in Example 1.

[0129] Example 10

[0130] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. Except that in the preparation process of the gas diffusion electrode based on the PTFE membrane, the concentration of copper ions in the copper salt solution in step (2) is 0.35 mol / L, and the thickness of the copper plating layer in the prepared gas diffusion electrode is 500 μm, the rest are the same as in Example 1.

[0131] Example 11

[0132] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. Except during the preparation of the PTFE-based gas diffusion electrode, in step (1), the loading of Pd in ​​PdCl2 on the PTFE membrane is 0.8 μg / cm³. 2 In the gas diffusion electrode prepared, the thickness of the copper plating layer is 45 μm and the oxidation time is 150 s, and the rest are the same as in Example 1.

[0133] Example 12

[0134] This embodiment provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. Except during the preparation of the PTFE-based gas diffusion electrode, in step (1), the amount of Pd in ​​PdCl2 on the PTFE membrane is 5.2 μg / cm³. 2 In the prepared gas diffusion electrode, the thickness of the copper plating layer is 450 μm, and the rest are the same as in Example 1.

[0135] Comparative Example 1

[0136] This comparative example provides a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) membrane. The PTFE membrane-based gas diffusion electrode includes a copper conductive layer stacked on the surface of the PTFE membrane, and a copper oxide catalyst supported on the surface of the copper conductive layer. The thickness of the copper conductive layer is 500 nm, and the loading of the copper oxide catalyst is 1 mg / cm³. 2 .

[0137] The method for preparing the gas diffusion electrode based on polytetrafluoroethylene film includes:

[0138] A 500 nm thick copper conductive layer was sputtered onto the surface of a polytetrafluoroethylene (PTFE) film using a copper target (99.99%) at a sputtering rate of 3.1 Å / s under a base pressure of 10⁻⁶ Torr. Then, a copper oxide catalyst prepared by a hydrothermal method was drop-coated onto the surface of the PTFE film with the copper conductive layer to obtain the gas diffusion electrode based on the PTFE film.

[0139] Performance testing:

[0140] All the gas diffusion electrodes provided in the above embodiments and comparative examples were directly used in a flowing gas diffusion electrolysis cell for electrocatalytic CO2 reduction. The catalyst reaction size was 1 cm × 1 cm. Except for a copper tape used to contact the copper layer (acting as a conductor), no copper tape was used around the materials to enhance conductivity. The CO2 gas flow rate was 30 mL / min. -1Under aeration conditions, the air in the electrolyte bottle was purged for 30 minutes or more. The material was pre-reduced before the reaction, in an electrocatalytic CO2 atmosphere at a potential of -1 to -3V (vs. RHE) for at least 120 seconds until the current stabilized. The CO2 reduction reaction was carried out in a constant current mode of -400mA. The reaction products were analyzed online by gas chromatography, using TCD and FID detectors for qualitative and quantitative analysis, respectively. Specific electrochemical performance and CO2 reduction performance are shown in Table 1, where -2V vs. RHE is the potential after 80% iR compensation. The linear voltammetry (LSV) curve of the gas diffusion electrode provided in Example 2 without iR compensation is shown in [Table 1]. Figure 2 The voltage-time (Ut) stability curve under a constant current of -400mA with 80% iR compensation is shown below. Figure 3 The yield of CO2 reduction products is shown in [reference needed]. Figure 4 Faraday efficiency diagram (see) Figure 5 .

[0141] Table 1

[0142]

[0143] Based on the test results in Table 1, this invention uses a hydrophobic porous polytetrafluoroethylene membrane as a carrier, with a copper plating layer stacked on its surface. The copper plating layer is then electro-oxidized to obtain a catalytically active copper oxide catalyst layer in situ. This allows for the preparation of a gas diffusion electrode without the need for additional catalyst loading, suitable for electrocatalytic CO2 reduction and conversion reactions. Furthermore, the electrode exhibits good conductivity, facilitating electron transport. The copper oxide layer, acting as a catalyst, is uniformly distributed, resulting in high electrocatalytic CO2 reduction and conversion activity, particularly for C-type reactions such as ethylene and ethanol. 2+ The product has high selectivity.

[0144] Based on the test results of Example 4, after depositing a copper-plated layer as a conductive layer on the surface of a hydrophobic porous polytetrafluoroethylene (PTFE) membrane using the preparation method provided by this invention, it can serve as a gas diffusion layer substrate. By coating any powdered catalyst onto the copper-plated surface, it can be used as a gas diffusion electrode for electrocatalytic CO2 reduction. The gas diffusion electrode prepared based on the copper-plated PTFE membrane obtained by this invention, using it as a substrate and loading a catalyst, exhibits high current density and high CO2 reactivity.

[0145] Based on the test results of Example 2 and Comparative Example 1, this invention, using a solution-based chemical copper plating process, prepares a relatively thick copper layer on the surface of a polytetrafluoroethylene (PTFE) film, and further modifies it in situ into a catalytically active copper oxide catalyst layer. There is no physical interface between the conductive layer and the catalytically active layer, which facilitates electron transport and results in good conductivity. Compared to the prior art, which involves depositing a nanometer-thick copper conductive layer on the PTFE film surface and then loading a conductive agent onto a gas diffusion electrode, this invention exhibits stronger electron transport capabilities and higher electrocatalytic CO2 reduction and conversion activity, particularly for C-type reactions such as ethylene and ethanol. 2+ The product selectivity is higher. Furthermore, this invention is based on a solution method, which does not require high-temperature treatment, and the polytetrafluoroethylene membrane has good weather resistance and better catalytic stability.

[0146] According to the test results of Examples 1, 5 and 6, if the copper plating layer thickness is too small, although it is beneficial to CO2 gas diffusion and mass transfer, it is not beneficial to electron transport and the current density decreases; if the copper plating layer thickness is too large, although it is beneficial to electron transport and the current density increases, it is not beneficial to CO2 gas diffusion and mass transfer and the CO2 reduction activity decreases.

[0147] Based on the test results of Examples 1, 7, and 8, during the preparation of the copper plating layer, if the temperature of the copper salt solution is too low, the reaction is slow and the copper layer is thin; if the temperature of the copper salt solution is too high, the reaction is vigorous and the copper plating layer is thick.

[0148] Based on the test results of Examples 1, 9, and 10, during the preparation of the copper plating layer, if the concentration of copper ions in the copper salt solution is low, the reaction is slow and the copper layer is thin; if the concentration of copper ions in the copper salt solution is high, the reaction is rapid and the copper plating layer is thick.

[0149] Based on the test results of Examples 1, 11, and 12, if the noble metal loading on the surface of the polytetrafluoroethylene film is low, there are fewer active sites for copper growth, which is not conducive to the electroless plating of copper; if the noble metal loading on the surface of the polytetrafluoroethylene film is high, there are more active sites, the copper plating reaction is more intense, and the copper layer is thicker.

[0150] In this invention, by increasing the volume of the polytetrafluoroethylene film and each solution, a large-area, uniform copper film can be prepared. Subsequently, through in-situ modification (such as electro-oxidation) or loading any powder catalyst, a large-size gas diffusion electrode can be prepared, which has the potential for industrial application.

[0151] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for low-temperature, large-area fabrication of a gas diffusion electrode based on a polytetrafluoroethylene (PTFE) film, characterized in that, The preparation method includes: A noble metal salt is coated on the surface of a polytetrafluoroethylene (PTFE) membrane, which is then immersed in a first reducing agent solution to obtain a noble metal-loaded PTFE membrane. The noble metal-loaded PTFE membrane is then immersed in a copper salt solution for a second immersion, while a second reducing agent solution is added to the copper salt solution to form a copper plating layer on the surface of the noble metal-loaded PTFE membrane. A catalyst layer is then deposited on the side of the copper plating layer away from the PTFE membrane to obtain the gas diffusion electrode based on the PTFE membrane. The thickness of the copper plating layer is 20μm~500μm; The catalyst layer is configured by: electropolishing the surface of the copper plating layer away from the polytetrafluoroethylene film, and then performing in-situ electro-oxidation on the electropolished copper plating layer to obtain a copper oxide catalyst layer; or, The catalyst layer is configured by loading a powdered catalyst onto the surface of a copper plating layer to obtain a powdered catalyst layer, wherein the powdered catalyst includes a MgCu bimetallic catalyst.

2. The preparation method according to claim 1, characterized in that, The noble metal salt includes any one or a combination of at least two of AuCl3, AgNO3, AgCl, PtCl4, H2PtCl6, PdCl2 or Pd(NO3)2; And / or, the loading of noble metals in the noble metal-loaded polytetrafluoroethylene membrane is 1 μg / cm³. 2 ~5μg / cm 2 ; And / or, the first reducing agent in the first reducing agent solution includes any one of sodium borohydride, lithium aluminum hydride, sodium cyanoborohydride or sodium aminoborohydride; And / or, the concentration of the first reducing agent in the first reducing agent solution is 0.05 g / L to 0.5 g / L; And / or, the second reducing agent in the second reducing agent solution includes formaldehyde and / or hydrazine; And / or, the concentration of the second reducing agent in the second reducing agent solution is 0.1 mol / L to 1.0 mol / L.

3. The preparation method according to claim 1 or 2, characterized in that, The copper salt in the copper salt solution includes copper nitrate and / or copper sulfate; And / or, the copper salt solution further includes disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate; And / or, the solvent of the copper salt solution includes a mixture of water and ethanol.

4. The preparation method according to claim 3, characterized in that, The concentration of copper ions in the copper salt solution is 0.1 mol / L to 0.5 mol / L; And / or, the total concentration of disodium ethylenediaminetetraacetate and / or dipotassium ethylenediaminetetraacetate in the copper salt solution is 0.15 mol / L to 0.6 mol / L; And / or, in the mixed solution, the volume ratio of water to ethanol is (1~5):

1.

5. The preparation method according to claim 1, characterized in that, The first soaking time is 15 min to 30 min; And / or, the second soaking time is 3 min to 60 min; And / or, during the second soaking process, the temperature of the copper salt solution is 60℃~80℃; And / or, during the second soaking process, the pH of the copper salt solution is adjusted to 12-13 using sodium hydroxide / potassium hydroxide.

6. The preparation method according to claim 1, characterized in that, The powdered catalyst loading is 0.5 mg / cm³. 2 ~5mg / cm 2 .

7. The preparation method according to claim 1, characterized in that, The thickness of the copper oxide catalyst layer is 2μm~15μm.

8. The preparation method according to claim 7, characterized in that, The voltage for the electropolishing treatment is 2V~6V vs. RHE; And / or, the polishing time is 5s to 100s.

9. A gas diffusion electrode based on a polytetrafluoroethylene film, characterized in that, The gas diffusion electrode based on the polytetrafluoroethylene film is prepared by the preparation method according to any one of claims 1 to 8; The gas diffusion electrode based on the polytetrafluoroethylene membrane includes a polytetrafluoroethylene membrane, a copper plating layer, and a catalyst layer stacked sequentially.

10. An application of the gas diffusion electrode based on a polytetrafluoroethylene film as described in claim 9, characterized in that, The gas diffusion electrode based on the polytetrafluoroethylene membrane is used as a cathode in the electrocatalytic CO2 reduction and conversion reaction.

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