An anionic ionomer modified silver-based electrode, its preparation method and application

Abstract

This invention relates to an anion ionomer-modified silver-based electrode, its preparation method, and its application. The preparation method includes the following steps: (1) using a titanium substrate as the working electrode, a titanium dioxide nanotube array electrode is obtained by electrochemical anodic oxidation, denoted as a TNT electrode substrate; (2) using the TNT electrode substrate obtained in step (1) as the working electrode, silver is deposited by electrodeposition to obtain a TNT composite electrode with deposited Ag, denoted as an Ag / TNT electrode; (3) an anion ionomer solution is sprayed onto the surface of the Ag / TNT electrode obtained in step (2) to complete the preparation of the anion ionomer-modified silver-based electrode. The electrode provided by this invention has excellent CO2 electroreduction performance and high selectivity for CO, enabling the control of the syngas ratio over a wide range, thereby meeting the needs of syngas preparation.

Description

Technical Field

[0001] This invention relates to the field of electrode preparation technology, specifically to an anion ionomer-modified silver-based electrode, its preparation method, and its application. Background Technology

[0002] Carbon dioxide (CO2) is a typical greenhouse gas. With rapid industrial development, the excessive combustion of fossil fuels has led to a sharp rise in atmospheric CO2 concentrations, causing many irreversible impacts on the environment and human society. Currently, there are various methods for CO2 treatment, mainly including capture and storage, chemical conversion, bioconversion, and physical adsorption technologies. Among these, using chemical conversion technologies to convert CO2 into renewable chemicals is an effective solution; for example, electrochemical CO2 reduction technology has attracted much attention due to its green sustainability and high economic value.

[0003] Currently, among the developed electrocatalysts, silver catalysts exhibit good CO2 electroreduction performance. However, their limited ability to bind intermediates COOH and CO leads to poor product selectivity and insufficient intrinsic activity, restricting the further development of silver catalysts in the industrial application of CO2 electroreduction. Furthermore, CO and H2, as important components of syngas, are crucial raw materials for many chemical industrial processes, and the CO / H2 ratio directly affects the type and quality of subsequent products.

[0004] Therefore, improving the selectivity of the products and controlling the CO / H2 ratio are urgent technical problems to be solved in the process of electroreduction of CO2. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an anion ionomer-modified silver-based electrode, its preparation method, and its application. Compared with existing technologies, the electrode provided by the present invention has excellent CO2 electroreduction performance and high selectivity for CO, and can achieve control of the syngas ratio over a wide range.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing an anionic ionomer-modified silver-based electrode, the method comprising the following steps:

[0008] (1) Using a titanium substrate as the working electrode, a titanium dioxide nanotube array electrode was obtained by electrochemical anodic oxidation, denoted as TNT electrode substrate;

[0009] (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, silver is deposited by electrodeposition to obtain a TNT composite electrode with deposited Ag, denoted as Ag / TNT electrode.

[0010] (3) Spray the anionic ionomer solution onto the surface of the Ag / TNT electrode obtained in step (2) to complete the preparation of the anionic ionomer-modified silver-based electrode.

[0011] The preparation method provided by this invention first employs an electrochemical anodic oxidation method to prepare a regularly arranged array of titanium dioxide nanotubes, which facilitates the loading of the active component Ag, exposes more active sites, and simultaneously aids in CO2 adsorption. Then, Ag is deposited via electrodeposition. Ag, being the main reactive active site, is an excellent metal electrocatalyst that readily generates CO, and electrodeposition further stabilizes the Ag loading. Finally, modification with an anionic ionomer is used. This modification improves the contact between the Ag / TNT electrode and the anion exchange membrane, facilitating the transport of substances and ions while reducing the overall ohmic resistance and significantly improving the electrochemical properties of the electrode. Furthermore, the anionic ionomer modification creates an alkaline reaction interface, promoting CO2 conversion to CO, inhibiting hydrogen evolution reaction, and improving product selectivity. Ultimately, the electrode prepared by this invention exhibits excellent CO2 electroreduction performance and excellent catalytic selectivity.

[0012] Preferably, the titanium substrate in step (1) comprises titanium foam.

[0013] In this invention, the foamed titanium generally needs to be cleaned before it can be used as a working electrode. The cleaning method can be a conventional method in the art, such as ultrasonic cleaning. The cleaning solution used can be any one or a combination of at least two of ethanol, acetone or water.

[0014] Preferably, the counter electrode used in the electrochemical anodic oxidation method comprises a platinum sheet.

[0015] Preferably, the electrolyte used in the electrochemical anodic oxidation method comprises an aqueous solution of ammonium fluoride in alcohol.

[0016] Preferably, the solvent for the aqueous alcoholic solution of ammonium fluoride includes ethylene glycol and deionized water.

[0017] Preferably, the mass percentage of deionized water in the ammonium fluoride aqueous solution is 2-5%, for example, it can be 2%, 3%, 4% or 5%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the mass percentage of NH4F in the aqueous alcoholic solution of ammonium fluoride is 0.5-1.5%, for example, it can be 0.5%, 0.6%, 0.8%, 1.0%, 1.2% or 1.5%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the bias voltage used in the electrochemical anodizing method is 30-50V, for example, it can be 30V, 32V, 35V, 38V, 40V, 42V, 45V, 48V or 50V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the oxidation time used in the electrochemical anodic oxidation method is 0.75-2h, for example, it can be 0.75h, 0.8h, 0.9h, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, after the electrochemical anodizing process described in step (1), the substrate is further subjected to cleaning, drying, and annealing to obtain a TNT electrode substrate.

[0022] Preferably, the cleaning solution used in step (1) includes ethanol.

[0023] Preferably, the annealing temperature is 350-550℃, for example, it can be 350℃, 370℃, 390℃, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, or 550℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the annealing time is 1-2 hours, for example, 1 hour, 1.5 hours or 2 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the electrode used in step (2) of the electrodeposition method includes a platinum sheet.

[0026] Preferably, the electrolyte used in the electrodeposition method includes a silver nitrate solution.

[0027] Preferably, the concentration of the silver nitrate solution is 0.05-0.1 mol / L, for example, it can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] In this invention, controlling the concentration of the silver nitrate solution is preferred, as it allows for reasonable adjustment of the deposition amount and state of metallic Ag. When the electrolyte concentration is too high, Ag nanoparticles tend to aggregate under the same deposition current conditions, reducing the catalyst's performance; when the electrolyte concentration is too low, the deposition amount is less, resulting in fewer active sites and reduced catalytic performance.

[0029] Preferably, the deposition time used in the electrodeposition method is 1-8 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min or 8 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In this invention, the deposition amount of metallic Ag can be reasonably controlled by optimizing the deposition time. If the deposition time is too long, Ag is prone to accumulate and may even block the TiO2 nanoarray, affecting gas diffusion; if the deposition time is too short, the Ag loading is low, affecting catalytic activity.

[0031] Preferably, the current density used in the electrodeposition method is 1-10 mA·cm⁻¹. -2 For example, it could be 1 mA·cm -2 2mA·cm -2 3mA·cm -2 4mA·cm -2 5mA·cm -2 6mA·cm -2 7mA·cm -2 8mA·cm -2 9mA·cm -2 or 10mA·cm -2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0032] Preferably, after the deposition in step (2) is completed, the electrode is cleaned to obtain an Ag / TNT electrode.

[0033] Preferably, the cleaning solution used in step (2) includes deionized water.

[0034] Preferably, the anionic ionomer in step (3) comprises a polyaromatic polymer whose main chain contains ether bonds and quaternary ammonium groups.

[0035] Preferably, the anionic ionomer comprises Fumion FAA-3.

[0036] In this invention, the above-mentioned specific anionic ionomer is preferably used because, on the one hand, the composition of the anionic ionomer is similar to that of the anionic membrane, which can make the contact between the catalyst and the membrane closer and facilitate ion transfer; on the other hand, the quaternary ammonium group contained in the ionomer is beneficial to the capture of the reactant CO2, while enhancing the basicity of the reaction interface, inhibiting the competing hydrogen evolution reaction, and improving the Faraday efficiency of the product CO.

[0037] Preferably, the solvent of the anionic ionomer solution includes N-methylpyrrolidone.

[0038] Preferably, the mass concentration of the anionic ionomer solution is 0.05%-5%, for example, it can be 0.05%, 0.1%, 0.5%, 0.8%, 1%, 2%, 3%, 4% or 5%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] In this invention, by optimally controlling the concentration of the anionic ionomer solution, the alkalinity of the catalyst surface can be improved, which is beneficial for the electroreduction of CO2 to CO. When the modification concentration is too high, it will cover the active site Ag, making it difficult for CO2 to be reduced; when the concentration is too low, the surface alkalinity weakens, the hydrogen evolution reaction is more likely to occur, and the Faraday efficiency of the product CO is reduced.

[0040] Preferably, the spraying amount of the anionic polymer solution is 0.05-0.1 mL / cm². 2 That is, 1cm 2 The electrode material is modified with an anionic polymer solution of volume 0.05-0.1 mL, for example, 0.05 mL / cm³. 2 0.06 mL / cm 2 0.07 mL / cm 2 0.08 mL / cm 2 0.09 mL / cm 2 Or 0.1 mL / cm 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0041] Preferably, vacuum drying is performed after spraying in step (3).

[0042] In this invention, the temperature, time and other conditions of the vacuum drying can adopt conventional parameters in the art, such as a temperature of 60-80℃ and a time of 10-12h.

[0043] As a preferred embodiment of the first aspect of the present invention, the preparation method includes the following steps:

[0044] (1) Using titanium foam as the working electrode, platinum sheet as the counter electrode, and ammonium fluoride alcohol aqueous solution as the electrolyte, electrochemical anodizing was performed for 0.75-2h under a bias voltage of 30-50V. Then, the electrode was cleaned and dried sequentially, and then annealed at 350-550℃ for 1-2h to obtain a TNT electrode substrate.

[0045] (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, a platinum sheet as the counter electrode, and a silver nitrate solution with a concentration of 0.05-0.1 mol / L as the electrolyte, an electrodeposition method is used at a current density of 1-10 mA·cm⁻¹. -2 Silver was deposited under the following conditions for 1-8 minutes, followed by washing to obtain an Ag / TNT electrode;

[0046] (3) Spray an anionic ionomer solution with a mass concentration of 0.05%-5% onto the surface of the Ag / TNT electrode obtained in step (2), and then vacuum dry it to complete the preparation of the anionic ionomer-modified silver-based electrode. The anionic ionomer includes Fumion FAA-3, and the solvent of the anionic ionomer solution is N-methylpyrrolidone.

[0047] In a second aspect, the present invention provides an anion ionomer-modified silver-based electrode, wherein the anion ionomer-modified silver-based electrode is obtained by the preparation method of the anion ionomer-modified silver-based electrode described in the first aspect of the present invention.

[0048] The anion ionomer-modified silver-based electrode provided by this invention has excellent CO2 electroreduction performance, high CO Faradaic efficiency, good catalytic selectivity, and can achieve syngas ratio control.

[0049] Thirdly, the present invention provides an application of an anion ionomer-modified silver-based electrode as described in the second aspect of the present invention, wherein the anion ionomer-modified silver-based electrode is used for the electroreduction of carbon dioxide.

[0050] The anionic ionomer-modified silver-based electrode provided by this invention is used for the electroreduction of carbon dioxide, which can efficiently convert CO2 into CO and has good catalytic selectivity.

[0051] Preferably, the bias voltage of the anion ionomer-modified silver-based electrode for electroreduction of carbon dioxide is -2.3 to -2.9V, for example, it can be -2.3V, -2.5V, -2.7V or -2.9V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably -2.7V.

[0052] Based on the silver-based electrode modified with the anionic ionomer provided by the present invention, further optimization of the bias voltage range can further improve the Faraday efficiency of CO and enhance catalytic selectivity.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The preparation method of the anionic ionomer-modified silver-based electrode provided by this invention is simple, enabling the electrode to have excellent CO2 electroreduction performance, while improving the Faradaic efficiency of CO and exhibiting excellent catalytic selectivity. Under optimal conditions, the Faradaic efficiency of CO reaches above 75.30%, the Faradaic efficiency of H2 reaches below 21.98%, and the current density reaches 21.23 mA / cm². 2 above.

[0055] (2) In the preparation method of silver-based electrode modified by anion ionomer provided by the present invention, by adjusting the modification concentration of the anion ionomer solution, the synthesis gas ratio (CO / H2) can be controlled within a wide range, thereby meeting the needs of synthesis gas preparation. Attached Figure Description

[0056] Figure 1 This is a graph showing the Faraday efficiency of the anion ionomer-modified silver-based electrode for products CO and H2 under different bias voltages, provided in Example 1 of this invention.

[0057] Figure 2 The graph shows the Faraday efficiency of the electrodes provided in Embodiments 1, 4-6 and Comparative Example 1 of this invention for the products CO and H2 under a bias voltage of -2.7V. Detailed Implementation

[0058] 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.

[0059] Example 1

[0060] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, the method comprising the following steps:

[0061] (1) Using titanium foam as the working electrode, platinum sheet as the counter electrode, and ammonium fluoride alcohol aqueous solution as the electrolyte, wherein the ammonium fluoride alcohol aqueous solution uses ethylene glycol and deionized water as solvents, wherein the mass percentage of deionized water is 2% and the mass percentage of NH4F is 0.5%, electrochemical anodizing is performed for 1 hour under a bias voltage of 50V, then the electrode is cleaned with ethanol and dried, and then annealed at 450℃ for 2 hours to obtain a TNT electrode substrate;

[0062] (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, a platinum sheet as the counter electrode, and a 0.1 mol / L silver nitrate solution as the electrolyte, an electrodeposition method is used at a current density of 5 mA·cm⁻¹. -2 Silver was deposited under the following conditions for 5 min, and then washed with deionized water to obtain an Ag / TNT electrode.

[0063] (3) Spray 0.5 mL of anionic ionomer (FumionFAA-3 produced by Fumasep Germany, with N-methylpyrrolidone as solvent) solution at a concentration of 0.1% onto the surface of the Ag / TNT electrode (a circular electrode with a diameter of 3 cm) obtained in step (2), and then vacuum dry at 60 °C for 12 h to complete the preparation of the silver-based electrode modified with anionic ionomer.

[0064] Example 2

[0065] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, the method comprising the following steps:

[0066] (1) Using titanium foam as the working electrode, platinum sheet as the counter electrode, and ammonium fluoride alcohol aqueous solution as the electrolyte, wherein the ammonium fluoride alcohol aqueous solution uses ethylene glycol and deionized water as solvents, wherein the mass percentage of deionized water is 5% and the mass percentage of NH4F is 1.5%, electrochemical anodizing is performed for 2 hours under a bias voltage of 30V, then the electrode is cleaned with ethanol and dried, and then annealed at 350℃ for 2 hours to obtain a TNT electrode substrate;

[0067] (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, a platinum sheet as the counter electrode, and a silver nitrate solution with a concentration of 0.08 mol / L as the electrolyte, an electrodeposition method is used at a current density of 10 mA·cm⁻¹. -2 Silver was deposited under the following conditions for 2 min, and then washed with deionized water to obtain an Ag / TNT electrode.

[0068] (3) Spray 0.7 mL of anionic ionomer (FumionFAA-3 produced by Fumasep Germany, with N-methylpyrrolidone as solvent) solution at a concentration of 0.1% onto the surface solution of the Ag / TNT electrode (a circular electrode with a diameter of 3 cm) obtained in step (2), and then vacuum dry at 60 °C for 12 h to complete the preparation of the silver-based electrode modified with anionic ionomer.

[0069] Example 3

[0070] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, the method comprising the following steps:

[0071] (1) Using titanium foam as the working electrode, platinum sheet as the counter electrode, and ammonium fluoride alcohol aqueous solution as the electrolyte, wherein the ammonium fluoride alcohol aqueous solution uses ethylene glycol and deionized water as solvents, wherein the mass percentage of deionized water is 5% and the mass percentage of NH4F is 1%, electrochemical anodic oxidation is performed for 0.8 h under a bias voltage of 40 V, then the electrode is cleaned with ethanol and dried, and then annealed at 500 °C for 1 h to obtain a TNT electrode substrate;

[0072] (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, a platinum sheet as the counter electrode, and a silver nitrate solution with a concentration of 0.07 mol / L as the electrolyte, an electrodeposition method is used at a current density of 2 mA·cm⁻¹. -2 Silver was deposited under the following conditions for 8 minutes, and then washed with deionized water to obtain an Ag / TNT electrode.

[0073] (3) Spray 0.35 mL of anionic ionomer (FumionFAA-3 produced by Fumasep Germany, with N-methylpyrrolidone as solvent) solution with a concentration of 0.1% onto the surface of the Ag / TNT electrode (a circular electrode with a diameter of 3 cm) obtained in step (2), and then vacuum dry it at 60 °C for 12 h to complete the preparation of the silver-based electrode modified with anionic ionomer.

[0074] Example 4

[0075] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, the only difference from Example 1 being that the concentration of the anionic ionomer solution is 0.05%.

[0076] Example 5

[0077] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, which differs from Example 1 only in that the concentration of the anionic ionomer solution is 0.5%.

[0078] Example 6

[0079] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, the only difference from Example 1 being that the concentration of the anionic ionomer solution is 1%.

[0080] Example 7

[0081] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode. The only difference from Example 1 is that the concentration of the silver nitrate solution used in the electrodeposition method is 0.01 mol / L.

[0082] Example 8

[0083] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode. The only difference from Example 1 is that the concentration of the silver nitrate solution used in the electrodeposition method is 0.2 mol / L.

[0084] Example 9

[0085] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, which differs from Example 1 only in that the deposition time of the electrodeposition method is 0.5 min.

[0086] Example 10

[0087] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode. The only difference from Example 1 is that the deposition time of the electrodeposition method is 10 min.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing a silver-based electrode. The only difference from Example 1 is that step (3) is omitted. The silver-based electrode is an Ag / TNT electrode.

[0090] Experiment to evaluate the activity of electroreducing CO2:

[0091] Activity evaluation experiments were conducted in a self-designed gas-solid phase electrochemical reaction cell. The reaction gas passed through the electrode surface of the cathode chamber in a single pass (electrodes provided in Examples 1-10 and Comparative Example 1, the electrodes being circular with a diameter of 3 cm). The initial reaction atmosphere in the cathode chamber consisted of 99.99% CO2, 100% relative humidity, and a gas flow rate of 20 mL / min. A 1 mol / L KOH solution was introduced into the anode chamber at a flow rate of 20 mL / min, and the counter electrode was nickel foam. The anode and cathode chambers were separated by an anion exchange membrane. The reaction was tested at 25°C and at one atmosphere. All electrochemical reactions were carried out using an electrochemical workstation, and the products were determined by gas chromatography under different bias voltages, and the Faraday efficiency of the products was calculated.

[0092] Taking Example 1 as an example, the Faraday efficiency of the silver-based electrode modified with a 0.1% anionic ionomer solution under different bias voltages for CO and H2 is as follows: Figure 1 As shown, from Figure 1 It can be seen that when the concentration of the anionic polymer solution is 0.1%, it has excellent CO2 electroreduction performance at a bias voltage of -2.7V, and the Faraday efficiency of CO reaches more than 85%.

[0093] Under a favorable bias voltage (-2.7V) for the electrochemical reduction of CO2, the electrodes provided in Examples 2-10 and Comparative Example 1 were subjected to activity evaluation experiments using the same testing method as in Example 1. The Faraday efficiency and current density of CO and H2 were measured, and the results are shown in Table 1. Examples 1, 4-6, and Comparative Example 1 are used as examples, and the results are as follows: Figure 2 As shown, from Figure 2 It can be seen that by adjusting the modification concentration of the anionic ionomer solution, the synthesis gas ratio (CO / H2) can be controlled within a wide range to meet the needs of synthesis gas preparation. When the concentration of the anionic ionomer solution is 0.1%, the Faraday efficiency of the product CO is the highest.

[0094] Table 1

[0095]

[0096]

[0097] The following points can be observed from the data in Table 1:

[0098] (1) As can be seen from the data in Examples 1-6, the anionic ionomer-modified silver-based electrode provided by the present invention, when used in the electrochemical reduction of CO2, achieves a current density of 21.23 mA / cm² under optimal conditions. 2 The above indicates that it has high reactivity, with the Faraday efficiency of CO reaching over 75.30% and the Faraday efficiency of H2 reaching below 21.98%, indicating high CO selectivity;

[0099] Furthermore, a comparison of Examples 1, 4-6, and Comparative Example 1 shows that the modification concentration of the anionic ionomer solution in Example 6 was too high, resulting in the coverage of the active site Ag and making CO2 difficult to reduce. Compared with Example 1, the Faradaic efficiency of CO was reduced. In Comparative Example 1, no anionic ionomer modification was used, and both the Faradaic efficiency of CO and the current density were significantly reduced compared with Example 1. Therefore, it can be seen that the present invention can further improve the reactivity and selectivity by using anionic ionomer modification and controlling the modification concentration.

[0100] (2) Data from Examples 1 and 7-8 show that in Example 7, the low concentration of silver nitrate solution resulted in a smaller Ag deposition amount and reduced catalytic performance; in Example 8, the high concentration of silver nitrate solution caused Ag nanoparticles to easily aggregate, hindering gas diffusion. Therefore, the Faraday efficiency of CO decreased in Examples 7-8 compared to Example 1. This demonstrates that the present invention, by optimally controlling the concentration of silver nitrate solution, can further regulate the Ag deposition amount, thereby further improving selectivity.

[0101] (3) Data from Examples 1 and 9-10 show that in Example 9, the electrodeposition time was too short, resulting in low Ag loading and affecting catalytic performance; in Example 10, the electrodeposition time was too long, easily leading to Ag accumulation and even clogging of the TiO2 nanoarray. Therefore, the Faraday efficiency of CO was lower in Examples 9-10 compared to Example 1. This demonstrates that the present invention, by optimizing the deposition time, can further regulate the amount of Ag deposited, thereby further improving selectivity.

[0102] In summary, the electrode provided by this invention has excellent CO2 electroreduction performance and high selectivity for CO, and can achieve control of the syngas ratio over a wide range.

[0103] 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 preparing an anionic ionomer-modified silver-based electrode, characterized in that, The preparation method includes the following steps: (1) Using a titanium substrate as the working electrode, a titanium dioxide nanotube array electrode was obtained by electrochemical anodic oxidation, denoted as TNT electrode substrate; (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, silver is deposited by electrodeposition to obtain a TNT composite electrode with deposited Ag, denoted as Ag / TNT electrode; (3) Spray the anion ionomer solution onto the surface of the Ag / TNT electrode obtained in step (2) to complete the preparation of the anion ionomer-modified silver-based electrode; The electrolyte used in the electrodeposition method includes silver nitrate solution; The concentration of the silver nitrate solution is 0.05-0.1 mol / L; The electrodeposition method used has a deposition time of 1-8 minutes; The mass concentration of the anionic polymer solution is 0.05%-5%; The anionic ionomer includes Fumion FAA-3.

2. The preparation method according to claim 1, characterized in that, The titanium substrate in step (1) includes titanium foam.

3. The preparation method according to claim 1, characterized in that, The counter electrode used in the electrochemical anodic oxidation method includes a platinum sheet.

4. The preparation method according to claim 1, characterized in that, The electrolyte used in the electrochemical anodic oxidation method includes an aqueous alcohol solution of ammonium fluoride.

5. The preparation method according to claim 4, characterized in that, The solvents for the ammonium fluoride aqueous solution include ethylene glycol and deionized water.

6. The preparation method according to claim 5, characterized in that, The mass percentage of deionized water in the ammonium fluoride aqueous solution is 2-5%.

7. The preparation method according to claim 4, characterized in that, The mass percentage of NH4F in the aqueous alcohol solution of the ammonium fluoride is 0.5-1.5%.

8. The preparation method according to claim 1, characterized in that, The bias voltage used in the electrochemical anodic oxidation method is 30-50V.

9. The preparation method according to claim 1, characterized in that, The oxidation time used in the electrochemical anodic oxidation method is 0.75-2 hours.

10. The preparation method according to claim 1, characterized in that, After the electrochemical anodizing process described in step (1), the substrate is further subjected to cleaning, drying and annealing to obtain the TNT electrode substrate.

11. The preparation method according to claim 10, characterized in that, The cleaning solution used in step (1) includes ethanol.

12. The preparation method according to claim 10, characterized in that, The annealing temperature is 350-550℃.

13. The preparation method according to claim 10, characterized in that, The annealing time is 1-2 hours.

14. The preparation method according to claim 1, characterized in that, The electrode used in step (2) of the electrodeposition method includes a platinum sheet.

15. The preparation method according to claim 1, characterized in that, The electrodeposition method uses a current density of 1-10 mA·cm. -2 .

16. The preparation method according to claim 1, characterized in that, After the deposition in step (2) is completed, the electrode is washed to obtain the Ag / TNT electrode.

17. The preparation method according to claim 16, characterized in that, The cleaning solution used in step (2) includes deionized water.

18. The preparation method according to claim 1, characterized in that, The solvent for the anionic ionomer solution includes N-methylpyrrolidone.

19. The preparation method according to claim 1, characterized in that, After spraying in step (3), vacuum drying is also performed.

20. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Using foamed titanium as the working electrode, platinum sheet as the counter electrode, and ammonium fluoride alcohol aqueous solution as the electrolyte, electrochemical anodizing was performed for 0.75-2h under a bias voltage of 30-50V. Then, the electrode was cleaned and dried sequentially, and then annealed at 350-550℃ for 1-2h to obtain a TNT electrode substrate. (2) Using the TNT electrode substrate obtained in step (1) as the working electrode, a platinum sheet as the counter electrode, and a silver nitrate solution with a concentration of 0.05-0.1 mol / L as the electrolyte, an electrodeposition method is used at a current density of 1-10 mA·cm⁻¹. -2 Silver was deposited under the following conditions for 1-8 minutes, followed by washing to obtain an Ag / TNT electrode; (3) Spray an anionic ionomer solution with a mass concentration of 0.05%-5% onto the surface of the Ag / TNT electrode obtained in step (2), and then vacuum dry it to complete the preparation of the silver-based electrode modified with anionic ionomer. The anionic ionomer includes Fumion FAA-3, and the solvent of the anionic ionomer solution is N-methylpyrrolidone.

21. A silver-based electrode modified with an anionic ionomer, characterized in that, The anion ionomer-modified silver-based electrode is obtained by the preparation method of the anion ionomer-modified silver-based electrode according to any one of claims 1-20.

22. An application of the anion ionomer modified silver-based electrode as described in claim 21, characterized in that, The anionic ionomer-modified silver-based electrode is used for the electroreduction of carbon dioxide.

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