Composite electrode for electrochemical direct air capture and method of making the same
By combining redox molecules with a gas permeation layer in electrochemical direct air capture to form an R-GPL composite electrode, the problem of easy deactivation of redox molecules in oxygen-containing atmospheres is solved, achieving efficient and stable carbon dioxide capture, which has broad prospects for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2026-01-28
- Publication Date
- 2026-06-05
AI Technical Summary
Existing redox reactive molecules are easily deactivated in oxygen-containing atmospheres, leading to a decrease in the efficiency of direct electrochemical air capture. Oxygen and carbon dioxide capture processes compete, reducing capture capacity and generating destructive superoxide radicals.
By combining redox molecules with a gas permeation layer rich in ether radicals to form an R-GPL composite electrode, the affinity of ether radicals is used to regulate the gas delivery channel, promote CO2 diffusion and hinder oxygen from contacting redox molecules, thereby achieving stable CO2 capture.
The oxygen-enriched conditions improved carbon dioxide capture capacity and Faraday efficiency, enhanced the stability of redox molecules, and extended the electrode's operating stability time, making it suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical direct air capture, specifically a method for applying a composite electrode in electrochemical direct air capture and its preparation method. More specifically, it relates to a composite electrode for electrochemical direct air capture and its preparation method. Background Technology
[0002] The combustion of fossil fuels has led to an increase in atmospheric carbon dioxide (CO2) concentration from 280 ppm in 1750 to 420 ppm (parts per million by volume) today. Direct air capture (DAC) can separate CO2 from the air, providing a promising carbon capture technology for achieving the goal of "carbon peaking and carbon neutrality." Traditional DAC technologies (such as solid-state amine methods and alkali-calcination methods) can achieve efficient atmospheric CO2 capture through chemical adsorption, but they generally suffer from high energy consumption (300-440 kJ / mol). -1 However, it faces challenges such as adsorbent oxidative degradation and large equipment footprint (Science, 2009, 325, 1599-1599; Nature Communications, 2020, 11, 2278). Electrochemical direct air capture (eDAC) technology using redox molecules can achieve reversible carbon dioxide capture at room temperature and with low energy cost, providing a promising alternative for sustainable atmospheric carbon dioxide removal.
[0003] In electrochemical carbon dioxide capture based on redox molecules, neutral redox molecules (denoted as R) have a weak affinity for carbon dioxide. However, after reduction, the resulting nucleophilic center combines with CO2 to form an R−CO2 adduct, which then oxidizes to release CO2 and regenerates the redox molecules. This reversible redox process not only achieves highly efficient eDAC but also continuously regenerates active molecules, thereby improving cycle stability. In eDAC systems, rational molecular design can adjust the affinity for CO2, achieving an optimal balance between redox potential, carbon dioxide capture capacity, and energy efficiency. Alexander C. Forse et al. from Stanford University (Journal of Materials Chemistry A, 2023, 11, 16221) used a diazo ion reaction to graft 2-aminoanthraquinone active molecules onto porous carbon surfaces to prepare quinone-based electrodes for electrochemical CO2 capture, achieving a capture efficiency of 0.4 mmol g under pure CO2 conditions. -1The CO2 capture capacity of Professor T. Alan Hatton's research group at MIT (Advanced. Material, 2024, 36, 2407567) has significantly accelerated mass transfer within the electrochemical reaction cell by loading polyanthraquinone onto a substrate to form a monolayer electrode, thereby effectively capturing CO2 from low-concentration point sources. Each gram of electrode can capture 1–0.4 mol of CO2. However, current research on immobilized redox molecules mainly focuses on improving CO2 capture capacity, but has not investigated improving the stability of redox-active molecules under oxygen-containing conditions. Oxygen sensitivity is a key challenge limiting electrochemical direct air capture (eDAC). The oxygen reduction reaction (ORR, O2 / O2) is generally thermodynamically more favorable than molecular redox reactions, which competes with molecular carbon capture processes, reducing capture capacity. Furthermore, oxygen can trigger molecular oxidation and deactivation, generating destructive superoxide radicals, which causes a continuous decline in CO2 capture capacity (Nature Energy, 2022, 7, 1065-1075; Journal of the American Chemical Society, 2022, 144, 14161-14169). Summary of the Invention
[0004] To address the issue that current methods of directly immobilizing redox-active molecules (such as quinone molecules immobilized on porous carbon substrates to form a monolayer electrode) for electrochemical CO2 capture are prone to deactivation in oxygen-containing atmospheres, we have combined redox molecules with a gas permeation layer (GPL) rich in ether radicals (−O−) to form an R-GPL composite electrode. Utilizing the affinity of −O− for polar CO2, an adjustable gas transport channel is formed, promoting CO2 diffusion while simultaneously hindering oxygen contact with the redox molecules. This achieves stable CO2 capture under oxygen-enriched conditions and has broad prospects for industrial development.
[0005] This invention provides a composite electrode for electrochemical direct air capture and its preparation method; to achieve the above objective, this invention provides a composite electrode with a redox-active molecule coupled to a gas permeation layer, the gas permeation layer having an adjustable gas selection channel, achieving stable carbon capture performance under oxygen-rich conditions.
[0006] The specific technical solution of the present invention is as follows:
[0007] A composite electrode for electrochemical direct air capture is an xR−yGPL electrode, where R represents redox active molecules, GPL represents the gas permeation layer, x represents the redox molecule loading, and y represents the gas permeation layer loading, where x = 2–10 mg cm⁻¹. −2 y = 0.2~1 mg cm −2The redox molecule contains two pyridine groups.
[0008] The composite electrode for electrochemical direct air capture has redox molecules of 2,2'-bipyridine, 4,4'-bipyridine, 2,5-bis(4-pyridyl)-1,3,4-thiadiazole, 1,4-bis(p-pyridyl)benzene, or 2,5-dipyridylthiophene.
[0009] The method for preparing a composite electrode for electrochemical direct air capture according to the present invention includes the following steps:
[0010] (1) Weigh solid redox molecules and disperse them in a volatile solvent, add naphthol to them, and sonicate to obtain an electrode dispersion;
[0011] (2) Spray the electrode dispersion from step (1) onto the carbon paper electrode to obtain the pre-electrode;
[0012] (3) Weigh the polymer used to form the GPL gas permeation layer and dissolve it in an ethanol / water mixed solvent to form a precursor solvent. Heat the mixture in a water bath to form a homogeneous solution.
[0013] (4) After the reaction is complete, the precursor solvent is diluted with the same solvent as in step (3) to obtain a diluted solution;
[0014] (5) The diluted solution obtained in step (4) is sprayed onto the side of the pre-electrode obtained in step (2) without electrode dispersion by solvent evaporation to form a gas permeation layer (GPL) and dried at room temperature to obtain a composite electrode.
[0015] The method for preparing the composite electrode for electrochemical direct air capture includes, in step (1), any combination of two solvents of N,N-dimethylformamide, ethanol, methanol, isopropanol, and chloroform.
[0016] The method for preparing the composite electrode for electrochemical direct air capture uses a volatile solvent volume ratio of 1:1.
[0017] The method for preparing the composite electrode for direct electrochemical air capture includes step (1) redox active molecules: solvent = 5-20 mg / mL; naphthol concentration is 2.5-10 wt%, and the amount used is 1:10-1:30 of the volatile solvent.
[0018] The method for preparing the composite electrode for electrochemical direct air capture, in step (2), the loading of redox molecules on the pre-electrode is 2–10 mg cm⁻¹. −2 .
[0019] The composite electrode preparation method for electrochemical direct air capture, in step (3), includes polyether copolyamide, polysulfone, and polyethyleneimine as the polymer used to form the GPL gas permeation layer; the concentration of the polymer is 20-100 mg / mL; and the volume ratio of the ethanol / water mixed solvent is 1:5-5:1.
[0020] In the method for preparing the composite electrode for electrochemical direct air capture, the concentration of the dilution solution in step (4) is 1 to 10 mg / mL.
[0021] The method for preparing the composite electrode for electrochemical direct air capture describes a method where the gas permeation layer in the composite electrode has a loading of 0.2–1 mg cm⁻¹. −2 .
[0022] The composite electrode of the present invention is applied in the field of electrochemical direct air capture.
[0023] The application method of this invention is described as follows:
[0024] A gas-phase circulating flow reaction cell system with a composite electrode for electrochemical direct air capture. This reaction system is a technological improvement on the existing electrochemical CO2 capture system. Figure 1 The specific steps are as follows:
[0025] (1) The prepared electrode was cut into 2×2 cm as the working electrode, the electrode loaded with lithium iron phosphate was used as the counter electrode, the electrolyte was LiTFSI / Bmim TFSI, and a cellulose membrane was used as the diaphragm to form the reaction cell.
[0026] (2) Connect the assembled reaction tank in step (1) to the gas pipeline to form a gas phase circulating flow reaction system; then introduce air at a flow rate of 4 sccm until the CO2 concentration at the outlet remains basically unchanged, indicating that CO2 is saturated and the following steps can be carried out.
[0027] (3) Connect the reaction system from step (2) to an electrochemical workstation and test the CO2 capture and release performance using air as the feed gas. Charge the system in constant current mode (applied current density is 0.2–1 mA cm⁻¹). −2 This is used to capture CO2. CO2 release is achieved through constant current discharge (applied current density of 0.2–1 mA cm⁻¹). −2 Based on the change in CO2 concentration at the outlet over time and the current-voltage curves during charging and discharging, the average CO2 capture capacity was calculated to be up to 2 mmol g. −1 分子 The Faraday efficiency can reach over 50%, while the quinone-supported electrode can only achieve 0.4 mmol g. -1 分子It has a CO2 capture capacity and a Faraday efficiency of about 25%.
[0028] The LiTFSI concentration can be 0.5~3 mol / L, preferably 1 mol / L.
[0029] The significant advantages of this invention are:
[0030] (1) This invention proposes for the first time a method for preparing a novel composite electrode for electrochemical direct air capture.
[0031] (2) The gas permeation layer in the composite electrode contains ether oxygen bonds, which can form a unique gas selective channel. Through physical sieving based on molecular dynamics diameter and different chemical interactions with polar carbon dioxide and nonpolar oxygen, it plays a role in selective gas transport, thereby selectively reducing the oxygen concentration at the electron carrier interface, suppressing oxygen-induced side reactions, and enhancing the capture stability of redox molecules in an oxygen-rich environment.
[0032] (3) Under conditions of 400 ppm CO2 and 21% O2, the direct CO2 capture capacity of the composite electrode reached 3 mmolg. –1 分子 Under conditions of 70% relative humidity (70% RH), the Faraday efficiency can also reach over 50%.
[0033] (4) Compared with the electrode without a gas permeation layer (the electrode with only redox molecules immobilized, Advanced.Material, 2024, 36, 2407567) has a stable operating time of less than 20 h under oxygen-containing conditions), the composite electrode with a gas permeation layer has stronger operating stability (> 25 h) and has practical industrial application potential. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of a gas-phase flow cell electrochemical direct air capture system.
[0035] Figure 2 These are front scanning electron microscope (SEM) images of the DPT-GPL composite electrode prepared in Example 1. a) is an SEM image of the DPT molecule; b) is a front GPL image of the GPL.
[0036] Figure 3 This is a cross-sectional SEM image of GPL in the DPT-GPL composite electrode prepared in Example 1.
[0037] Figure 4 These are front scanning electron microscope (SEM) images of the BPT-GPL composite electrode prepared in Example 2: a) is an SEM image of the BPT molecule; b) is a front GPL image of the GPL.
[0038] Figure 5 This is a cross-sectional SEM image of GPL in the BPT-GPL composite electrode prepared in Example 2.
[0039] Figure 6 These are front scanning electron microscope (SEM) images of the BPy−GPL composite electrode prepared in Example 3. a) is an SEM image of the BPy molecule; b) is a front GPL image of GPL.
[0040] Figure 7 This is a cross-sectional SEM image of GPL in the BPy−GPL composite electrode prepared in Example 3.
[0041] Figure 8 The time-CO2 concentration change curves obtained by electrochemically capturing CO2 in dry air using the DPT-GPL, BPT-GPL and BPy-GPL composite electrodes obtained in Example 4 are shown.
[0042] Figure 9 This is a graph showing the average capture capacity of CO2 in dry air by the DPT-GPL, BPT-GPL and BPy-GPL composite electrodes obtained in Example 4.
[0043] Figure 10 This is a diagram showing the Faraday current efficiency of the DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes obtained in Example 4 for the electrochemical capture of CO2 from dry air.
[0044] Figure 11 The average capture capacity of the BPT-GPL composite electrode obtained in Examples 5 and 6 for electrochemical CO2 capture under different humidity conditions is shown.
[0045] Figure 12 The Faraday efficiency of the BPT-GPL composite electrode obtained in Examples 5 and 6 for electrochemical CO2 capture under different humidity conditions is shown. Detailed Implementation
[0046] The present invention will be further described in detail below through specific embodiments, but the implementation methods of the present invention are not limited thereto. The following embodiments will enable those skilled in the art to have a more comprehensive understanding of the present invention.
[0047] Example 1
[0048] (1) Accurately weigh 10 mg of redox molecules DPT and disperse it in 1 mL of ethanol / chloroform mixed solution (the volume ratio of ethanol and chloroform is 1:1), and add 33 μL of naphthol (2.5 wt%) to it. Sonicate for 1 h to obtain electrode dispersion.
[0049] (2) The electrode dispersion was sprayed onto the carbon paper electrode to obtain a DPT loading of 2 mg cm⁻¹. −2 The pre-electrode is stored for future use;
[0050] (3) Accurately weigh 5 g of polymer PSF and dissolve it in 50 mL of ethanol / water mixed solvent (the volume ratio of ethanol to water is 2:1) to form a precursor solvent (at this time, the concentration of polymer is 100 mg / mL). Heat in a water bath to form a homogeneous solution.
[0051] (4) After the reaction is complete, the precursor solvent is diluted 10 times with the same solvent as in step (3) to obtain a diluted solution (at this time, the concentration of polymer PSF is 10 mg / mL).
[0052] (5) The diluted solution obtained in step (4) is sprayed onto the side of the pre-electrode obtained in step (2) without electrode dispersion by solvent evaporation to form a gas permeation layer (GPL), and dried at room temperature for 24 h to obtain a DPT-GPL composite electrode (at this time, the GPL loading is 1 mg cm⁻¹). −2 ).
[0053] like Figure 2 As shown in Figure a, in the composite electrode of Example 1, DPT molecules are in the form of nanoparticles on the electrode surface. Figure 2 b is a SEM image of the gas permeation layer formed by polysulfone, which forms a uniform coating on the electrode surface. Figure 3 The cross-sectional SEM image of the GPL layer shows that the thickness of the GPL layer is about 5 μm, which proves the successful preparation of the GPL layer.
[0054] Example 2
[0055] (1) Accurately weigh 20 mg of redox molecules BPT and disperse it in 1 mL of isopropanol / chloroform mixed solution (the volume ratio of isopropanol and chloroform is 1:1), and add 50 μL of naphthol (5wt%) to it. Sonicate for 1 h to obtain electrode dispersion.
[0056] (2) The electrode dispersion was sprayed onto the carbon paper electrode to obtain a BPT loading of 5 mg cm⁻¹. −2 The pre-electrode is stored for future use;
[0057] (3) Accurately weigh 5 g of the polymer Pebax and dissolve it in 250 mL of ethanol / water mixed solvent (the volume ratio of ethanol to water is 1:5) to form precursor solvent C (at this time, the concentration of the polymer is 20 mg / mL). Heat in a water bath to form a homogeneous solution.
[0058] (4) After the reaction is complete, the precursor solvent is diluted 4 times with the same solvent as in step (3) to obtain solution D (at this time, the concentration of polymer Pebax is 5 mg / mL).
[0059] (5) The solution D obtained in step (4) is sprayed onto the side of electrode B without electrode dispersion by solvent evaporation to form a gas permeation layer (GPL), and dried at room temperature for 24 h to obtain the BPT−GPL composite electrode (at this time, the GPL loading is 0.5 mg cm⁻¹). −2 Save for later use.
[0060] Figure 4 a is a SEM image of the BPT-GPL composite electrode prepared in Example 2. It can be seen from the image that the redox molecule BPT exhibits a nano-trapezoidal appearance and is attached to the carbon fiber surface. Figure 4 b is a front-side SEM image of the prepared BPT-GPL composite electrode. Figure 5 In this process, GPL forms a uniform layer on the substrate surface with a certain degree of roughness and a thickness of approximately 1 μm. Figure 4 , Figure 5 The results showed that both the molecules and the GPL layer were successfully loaded onto the carbon paper.
[0061] Example 3
[0062] (1) Accurately weigh 5 mg of redox molecules BPy and disperse them in 1 mL of isopropanol / N'N-dimethylformamide mixed solution (the volume ratio of isopropanol and N'N-dimethylformamide is 1:1), and add 100 μL of naphthol (10wt%) to it. Sonicate for 1 h to obtain electrode dispersion.
[0063] (2) The electrode dispersion was sprayed onto a carbon paper electrode to obtain a BPT loading of 10 mg cm⁻¹. −2 The pre-electrode is stored for future use;
[0064] (3) Accurately weigh 5 g of polymer PEI and dissolve it in 100 mL of ethanol / water mixed solvent (the volume ratio of ethanol to water is 5:1) to form a precursor solvent (at this time, the concentration of polymer is 50 mg / mL). Heat in a water bath to form a homogeneous solution.
[0065] (4) After the reaction is complete, the precursor solvent is diluted 50 times with the same solvent as in step (3) to obtain a diluted solution (the concentration of polymer Pebax is 1 mg / mL).
[0066] (5) The diluted solution obtained in step (4) is sprayed onto the side of the pre-electrode obtained in step (2) without electrode dispersion by solvent evaporation to form a gas permeation layer (GPL), and dried at room temperature for 24 h to obtain a BPT-GPL composite electrode (at this time, the GPL loading is 0.2 mg cm⁻¹). −2 Save for later use.
[0067] Figure 6 a is a SEM image of the BPy−GPL composite electrode prepared in Example 3. It can be seen from the image that the redox molecules BPy are mainly attached to the surface of the carbon fiber, and their appearance is a vertically arranged nano-pyramid. Figure 6 b is a front-side SEM image of the prepared BPT-GPL composite electrode, showing that the polymer forms a uniform coating layer on the substrate. Figure 7 The cross-sectional view of the GPL shows that its thickness is several hundred nanometers. Because the capping layer is relatively thin, its cross-sectional area is prone to curling, making it difficult to accurately measure its thickness. Figure 6 , Figure 7 The results showed that both the molecules and the GPL layer were successfully loaded onto the carbon paper.
[0068] Example 4
[0069] The application of composite electrodes in the electrochemical capture of dry air (400 ppm CO2 + 21% O2) in a gas-phase circulating flow reaction system is illustrated by the following steps:
[0070] (1) Preparation of working electrode: The electrodes prepared in Examples 1 to 3 were cut into 2×2 cm pieces to serve as working electrodes. A commercial lithium iron phosphate electrode was used as the counter electrode, 1 M LiTFSI / Bmim TFSI was used as the electrolyte solution, and a cellulose membrane was used as the diaphragm to form a gas-phase flow reaction cell;
[0071] (2) Connect the assembled reaction tank in step (1) to the gas pipeline to form a gas-phase circulating reaction system. Then, introduce dry air (400 ppm CO2 + 21% O2) at a flow rate of 4 sccm until the CO2 concentration at the outlet is maintained at about 400 ppm, indicating that CO2 is saturated and the following steps can be carried out.
[0072] (3) Connect the reaction system from step (2) to an electrochemical workstation and perform a CO2 capture-release performance test by charging in constant current mode (current density of 0.2 mA cm⁻¹). −2 The device was charged for 15 minutes and then rested for 35 minutes to allow for sufficient CO2 capture. CO2 release was achieved through constant current discharge (current density of 0.2 mA cm⁻¹). −2The gas is charged for 15 minutes and then allowed to rest for 30 minutes to ensure complete CO2 release. The average CO2 capture capacity and Faraday efficiency are calculated based on the change in CO2 concentration at the outlet over time and the charge / discharge amount.
[0073] Figure 8 The figures show the time-CO2 concentration variation curves of the DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes. As can be seen from the figures, the DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes all exhibit stable CO2 concentration oscillations, indicating that these composite electrodes can stably capture and release CO2 from the air under oxygen-rich conditions.
[0074] Figure 9 The average CO2 capture capacity of the DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes is obtained from the time-CO2 concentration change curve. Figure 9 We can see that the average CO2 capture capacity of the DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes prepared in Examples 1-3 all exceed 2 mmol g. −1 分子 .
[0075] Figure 10 The graphs show the Faradaic efficiencies of DPT-GPL, BPT-GPL, and BPy-GPL composite electrodes for electrochemical CO2 capture, primarily depicting the changes in the Faradaic efficiency of molecules for carbon capture as the capture-release cycle progresses. The Faradaic efficiency remains essentially constant with increasing reaction time, consistently exceeding 60%. The optimal BPT-GPL composite electrode achieves a Faradaic efficiency of 78%.
[0076] Example 5
[0077] The application of composite electrodes in the electrochemical capture of low-humidity air (400 ppm CO2 + 21% O2, 30% RH) in a gas-phase circulating flow reaction system is illustrated by the following steps:
[0078] (1) Preparation of working electrode: The BPT-GPL composite electrode prepared in Example 2 above was cut into 2×2 cm as the working electrode. A commercial lithium iron phosphate electrode was used as the counter electrode, 1 M LiTFSI / Bmim TFSI was used as the electrolyte solution, and a cellulose membrane was used as the diaphragm to form a gas-phase flow reaction cell;
[0079] (2) Connect the assembled reaction tank in step (1) to the gas pipeline to form a gas-phase circulating reaction system. Then, introduce air with different humidity (400 ppm CO2 + 21% O2, 70% RH) at a flow rate of 4 sccm until the CO2 concentration at the outlet is maintained at around 400 ppm, indicating that CO2 is saturated and the following steps can be carried out.
[0080] (3) Connect the reaction system from step (2) to an electrochemical workstation and perform a CO2 capture-release performance test. Charge the system in constant current mode (current density of 0.6 mA cm⁻¹). −2 The system was charged for 15 minutes and then allowed to rest for 35 minutes to fully capture CO2. CO2 release was achieved through constant current discharge (current density 0.6 mA cm⁻¹). −2 The gas is charged for 15 minutes and then allowed to rest for 30 minutes to ensure complete CO2 release. The average CO2 capture capacity and Faraday efficiency are calculated based on the change in CO2 concentration at the outlet over time and the charge / discharge amount.
[0081] Example 6
[0082] The application of composite electrodes in the electrochemical capture of high-humidity air (400 ppm CO2 + 21% O2, 70% RH) in a gas-phase circulating flow reaction system is illustrated by the following steps:
[0083] (1) Preparation of working electrode: The BPT-GPL composite electrode prepared in Example 2 above was cut into 2×2 cm as the working electrode. A commercial lithium iron phosphate electrode was used as the counter electrode, 1 M LiTFSI / Bmim TFSI was used as the electrolyte solution, and a cellulose membrane was used as the diaphragm to form a gas-phase flow reaction cell;
[0084] (2) Connect the assembled reaction tank in step (1) to the gas pipeline to form a gas-phase circulating reaction system. Then, introduce air with different humidity (400 ppm CO2 + 21% O2, 70% RH) at a flow rate of 4 sccm, and continuously monitor the CO2 concentration at the outlet using a CO2 sensor.
[0085] (3) Connect the reaction system from step (2) to an electrochemical workstation and perform a CO2 capture-release performance test by charging in constant current mode (current density of 1 mA cm⁻¹). −2 The system is charged for 15 minutes and then rested for 35 minutes to allow for sufficient CO2 capture. CO2 release is achieved through constant current discharge (current density 1 mA cm⁻¹). −2The gas is charged for 15 minutes and then allowed to rest for 30 minutes to ensure complete CO2 release. The average CO2 capture capacity and Faraday efficiency are calculated based on the change in CO2 concentration at the outlet over time and the charge / discharge amount.
[0086] Figure 11 The figure shows the average CO2 capture capacity of the BPT-GPL composite electrode for electrochemical carbon capture using air with different humidity levels (dry, 20%, 70%) as the feed gas. As can be seen from the figure, the BPT-GPL composite electrode exhibits a high average CO2 capture capacity (2.4 mmol g) for all air with different humidity levels as the feed gas. −1 分子 about).
[0087] Figure 12 This is a Faraday efficiency graph for electrochemical carbon capture using BPT-GPL composite electrodes with air at different humidity levels (dry, 20%, 70%) as the feed gas. It primarily describes the change in Faraday efficiency with variations in the humidity of the feed gas. Figure 12 We can see that the BPT-GPL composite electrode prepared in Example 2 can separate CO2 from the air under different humidity conditions (dry, 20%, 70%). Even when the relative humidity in the air reaches 70%, the BPT-GPL composite electrode can still separate CO2 from the air and maintain a relatively high Faraday efficiency (55%).
[0088] It is evident that, regardless of whether the air is dry or humid, the composite electrode prepared in this example can efficiently separate CO2 from the air, demonstrating superior performance and broad prospects for industrial applications.
[0089] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.
Claims
1. A composite electrode for electrochemical direct air capture, characterized in that, The composite electrode is an xR−yGPL electrode, where R represents the redox active molecule, GPL represents the gas permeation layer, x represents the redox molecule loading, and y represents the gas permeation layer loading, where x = 2–10 mg cm⁻¹. −2 y = 0.2~1 mg cm −2 The redox molecule contains two pyridine groups.
2. The composite electrode for electrochemical direct air capture as described in claim 1, characterized in that, The redox molecules are 2,2'-bipyridine, 4,4'-bipyridine, 2,5-bis(4-pyridyl)-1,3,4-thiadiazole, 1,4-bis(p-pyridyl)benzene, or 2,5-dipyridylthiophene.
3. A method for preparing a composite electrode for electrochemical direct air capture, characterized in that, Includes the following steps: (1) Weigh solid redox molecules and disperse them in a volatile solvent, add naphthol to them, and sonicate to obtain an electrode dispersion; (2) Spray the electrode dispersion from step (1) onto the carbon paper electrode to obtain the pre-electrode; (3) Weigh the polymer used to form the GPL gas permeation layer and dissolve it in an ethanol / water mixed solvent to form a precursor solvent. Heat the mixture in a water bath to form a homogeneous solution. (4) After the reaction is complete, the precursor solvent is diluted with the same solvent as in step (3) to obtain a diluted solution; (5) The diluted solution obtained in step (4) is sprayed onto the side of the pre-electrode obtained in step (2) without electrode dispersion by solvent evaporation to form a gas permeation layer (GPL) and dried at room temperature to obtain a composite electrode.
4. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, The volatile solvents in step (1) include any combination of two solvents such as N,N-dimethylformamide, ethanol, methanol, isopropanol, and chloroform.
5. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, The volume ratio of volatile solvents is 1:
1.
6. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, Step (1) Redox active molecules: solvent = 5-20 mg / mL; naphthol concentration is 2.5-10 wt%, and the amount used is 1:10-1:30 of the volatile solvent.
7. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, In step (2), the loading of redox molecules on the pre-electrode is 2–10 mg cm⁻¹. −2 .
8. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, The polymers used to form the GPL gas permeation layer in step (3) include polyether copolyamide, polysulfone, and polyethyleneimine; the concentration of the polymer is 20 to 100 mg / mL; and the volume ratio of the ethanol / water mixed solvent is 1:5 to 5:
1.
9. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, The concentration of the diluted solution in step (4) is 1 to 10 mg / mL.
10. The method for preparing a composite electrode for electrochemical direct air capture as described in claim 3, characterized in that, The gas permeation layer loading in the composite electrode is 0.2–1 mg cm⁻¹. −2 .