Anion ionomer modified silver-based electrode and preparation method and application thereof

Abstract

The invention relates to an anion ionomer modified silver-based electrode and a preparation method and application thereof, and the preparation method comprises the following steps: (1) taking a titanium substrate as a working electrode, obtaining a titanium dioxide nanotube array electrode through an electrochemical anodic oxidation method, and recording the titanium dioxide nanotube array electrode as a TNT electrode substrate; (2) by taking the TNT electrode substrate obtained in the step (1) as a working electrode, depositing silver by adopting an electro-deposition method to obtain an Ag-deposited TNT composite electrode which is marked as an Ag / TNT electrode; and (3) spraying an anion ionomer solution on the surface of the Ag / TNT electrode obtained in the step (2) to complete the preparation of the anion ionomer modified silver-based electrode. The electrode provided by the invention has excellent CO2 electroreduction performance and relatively high CO selectivity, and can realize regulation and control of a synthetic gas proportion in a relatively wide range, so that the requirement of preparing the synthetic gas is met.

Description

Technical Field

[0001] The invention relates to the technical field of electrode preparation, and in particular to an anionic ionomer-modified silver-based electrode and a preparation method and application thereof. Background Art

[0002] Carbon dioxide (CO2) is a typical greenhouse gas. With the rapid development of industry, the excessive burning of fossil fuels has led to a sharp increase in the concentration of CO2 in the atmosphere, causing many irreversible impacts on the environment and human society. At present, there are many methods for treating CO2, mainly including capture and storage, chemical conversion, biological conversion and physical adsorption. Among them, the use of chemical conversion technology to convert CO2 into renewable chemicals is an effective solution. For example, electrochemical reduction of CO2 technology has attracted much attention due to its green sustainability and high economic value.

[0003] At present, among the developed electrocatalysts, silver catalysts show good CO2 electroreduction performance, but their binding ability to the intermediates COOH and CO is limited, resulting in poor product selectivity and insufficient intrinsic activity, which limits the further development of silver catalysts in the industrial application of CO2 electroreduction. In addition, CO and H2, as important components of syngas, are important raw materials for many chemical industrial processes, and the CO / H2 ratio directly affects the type and quality of subsequent products.

[0004] Therefore, in the process of electroreduction of CO2, how to improve the selectivity of the product and regulate the ratio of CO / H2 are technical problems that need to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an anionic ionomer modified silver-based electrode and a preparation method and application thereof. Compared with the prior art, the electrode provided by the present invention has excellent CO2 electroreduction performance and high selectivity for CO, and can achieve regulation of the synthesis gas ratio in a wider range.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

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

[0008] (1) Using titanium substrate as working electrode, titanium dioxide nanotube array electrode was obtained by electrochemical anodization method, which was denoted as TNT electrode substrate;

[0009] (2) using the TNT electrode substrate obtained in step (1) as a working electrode, and depositing silver by electrodeposition to obtain a TNT composite electrode deposited with Ag, which is referred to as an Ag / TNT electrode;

[0010] (3) Spraying 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] In the preparation method provided by the present invention, firstly, an electrochemical anodic oxidation method is used to prepare a regularly arranged titanium dioxide nanotube array, which is helpful for the loading of the active component Ag, exposing more active sites, and at the same time helping to adsorb CO2; then Ag is deposited by an electrodeposition method, Ag is the main reactive active site, and is an excellent metal electrocatalyst that is easy to produce CO, and the loading of Ag is made more stable by the electrodeposition method; finally, an anionic ionomer is used for modification, which can make the Ag / TNT electrode and the anionic membrane contact more closely, which is conducive to the transmission of substances and ions, and at the same time reduces the overall ohmic resistance, greatly improving the electrochemical properties of the electrode, and on the other hand, an anionic ionomer is used for modification, which can make the reaction interface present an alkaline state, which is helpful for the conversion of CO2 into CO, inhibits the occurrence of hydrogen evolution reaction, and improves the selectivity of the product. Finally, the electrode prepared by the present invention has excellent CO2 electroreduction performance and excellent catalytic selectivity.

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

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

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

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

[0016] Preferably, the solvent of the alcohol aqueous solution of ammonium fluoride comprises ethylene glycol and deionized water.

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

[0018] Preferably, the mass percentage of NH4F in the alcohol aqueous 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, and other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the bias voltage used in the electrochemical anodization 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, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the oxidation time adopted in the electrochemical anodization 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, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, after the electrochemical anodization method in step (1), cleaning, drying and annealing are performed in sequence to obtain a TNT electrode substrate.

[0022] Preferably, the washing solution used in step (1) comprises ethanol.

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

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

[0025] Preferably, the counter electrode used in the electrodeposition method in step (2) comprises 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, and other unlisted values ​​within the numerical range are also applicable.

[0028] In the present invention, it is preferred to control the concentration of the silver nitrate solution, so that the deposition amount and state of the metal Ag can be reasonably adjusted. When the electrolyte concentration is too high, under the same deposition current conditions, the Ag nanoparticles are easy to agglomerate, reducing the performance of the catalyst; when the electrolyte concentration is too low, the deposition amount is small, 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, and other unlisted values ​​within the numerical range are also applicable.

[0030] In the present invention, by optimally controlling the deposition time, the deposition amount of metal Ag can be reasonably regulated. When the deposition time is too long, Ag accumulation is easily formed, and even the TiO2 nanoarray is blocked, and gas diffusion is affected; when the deposition time is too short, the Ag loading is small, which affects the catalytic activity.

[0031] Preferably, the current density used in the electrodeposition method is 1-10 mA·cm -2 , for example, it can 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 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

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

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

[0034] Preferably, the anionic ionomer in step (3) comprises a polyaromatic polymer having an ether bond in the main chain and a quaternary ammonium group.

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

[0036] In the present invention, the above-mentioned specific anionic ionomer is preferably used. On the one hand, it is because the above-mentioned anionic ionomer has similar components to the anionic membrane, which can make the contact between the catalyst and the membrane closer and facilitate the transfer of ions; on the other hand, it is because the quaternary amine group contained in the ionomer is beneficial to the capture of the reactant CO2, while enhancing the alkalinity of the reaction interface, inhibiting the competitive hydrogen evolution reaction, and improving the Faraday efficiency of the product CO.

[0037] Preferably, the solvent of the anionic ionomer solution comprises 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, and other unlisted values ​​within the numerical range are also applicable.

[0039] In the present invention, by preferably controlling the concentration of the anionic ionomer solution, the alkalinity of the catalyst surface can be improved, which is beneficial to the electroreduction of CO2 to CO. When the modification concentration is too high, the active site Ag will be covered, making it difficult to reduce CO2; when the concentration is too low, the surface alkalinity is weakened, 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 ionomer solution is 0.05-0.1 mL / cm 2 , i.e. 1cm 2 The electrode material modification volume is 0.05-0.1 mL of anionic ionomer solution, for example, 0.05 mL / cm 2 , 0.06mL / cm 2 , 0.07mL / cm 2 , 0.08mL / cm 2 , 0.09mL / cm 2 or 0.1mL / cm 2 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

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

[0042] In the present 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° C. and a time of 10-12 h.

[0043] As a preferred technical solution of the first aspect of the present invention, the preparation method comprises the following steps:

[0044] (1) using titanium foam as a working electrode, a platinum sheet as a counter electrode, and an alcohol aqueous solution of ammonium fluoride as an electrolyte, electrochemically anodizing for 0.75-2 h at a bias voltage of 30-50 V, then washing and drying in sequence, and then annealing at 350-550° C. for 1-2 h 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 -2 Silver is deposited for 1-8 min under the conditions of , and then washed to obtain an Ag / TNT electrode;

[0046] (3) spraying an anionic ionomer solution with a mass concentration of 0.05%-5% on the surface of the Ag / TNT electrode obtained in step (2), and then vacuum drying to complete the preparation of the anionic ionomer modified silver-based electrode, wherein 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 anionic ionomer-modified silver-based electrode, wherein the anionic ionomer-modified silver-based electrode is obtained by the preparation method of the anionic ionomer-modified silver-based electrode described in the first aspect of the present invention.

[0048] The anionic ionomer-modified silver-based electrode provided by the present invention has excellent CO2 electroreduction performance, high CO Faraday efficiency, good catalytic selectivity, and can achieve synthesis gas ratio regulation.

[0049] In a third aspect, the present invention provides a use of an anionic ionomer-modified silver-based electrode as described in the second aspect of the present invention, wherein the anionic ionomer-modified silver-based electrode is used for electroreduction of carbon dioxide.

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

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

[0052] On the basis of using the anionic ionomer modified silver-based electrode provided by the present invention, the above-mentioned bias voltage range is further preferably controlled, which can further improve the Faraday efficiency of CO and improve the 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 the present invention is simple, and can make the electrode have excellent CO2 electroreduction performance, while improving the Faraday efficiency of CO, and having excellent catalytic selectivity. Under optimal conditions, the Faraday efficiency of CO reaches more than 75.30%, the Faraday efficiency of H2 reaches less than 21.98%, and the current density reaches 21.23 mA / cm 2 above.

[0055] (2) In the preparation method of the anionic ionomer modified silver-based electrode provided by the present invention, by adjusting the modified concentration of the anionic ionomer solution, the synthesis gas ratio (CO / H2) can be regulated within a wide range, thereby meeting the needs of preparing synthesis gas. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0057] Figure 2 This is a graph showing the Faraday efficiency results of the electrodes provided in Example 1, Examples 4-6 and Comparative Example 1 of the present invention for the products CO and H2 at a bias voltage of -2.7V. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0059] Example 1

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

[0061] (1) Using titanium foam as a working electrode, a platinum sheet as a counter electrode, and an alcohol aqueous solution of ammonium fluoride as an electrolyte, wherein the alcohol aqueous solution of ammonium fluoride 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 anodization is performed at a bias voltage of 50 V for 1 hour, and then the electrode is cleaned with ethanol and dried, and then annealed at 450° C. for 2 hours to obtain a TNT electrode substrate;

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

[0063] (3) Spray 0.5 mL of a 0.1% anionic ionomer solution (Fumion FAA-3 produced by Fumasep Germany, solvent: N-methylpyrrolidone) onto the surface of the Ag / TNT electrode (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 anionic ionomer-modified silver-based electrode.

[0064] Example 2

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

[0066] (1) Using titanium foam as a working electrode, a platinum sheet as a counter electrode, and an alcohol aqueous solution of ammonium fluoride as an electrolyte, wherein the alcohol aqueous solution of ammonium fluoride 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 anodization is performed for 2 hours under a bias voltage of 30 V, and then the electrode is cleaned with ethanol and dried, and then annealed at 350° C. for 2 hours to obtain a TNT electrode substrate;

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

[0068] (3) Spray 0.7 mL of a 0.1% anionic ionomer solution (Fumion FAA-3 produced by Fumasep Germany, solvent: N-methylpyrrolidone) onto the surface of the Ag / TNT electrode (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 anionic ionomer-modified silver-based electrode.

[0069] Example 3

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

[0071] (1) Using titanium foam as a working electrode, a platinum sheet as a counter electrode, and an alcohol aqueous solution of ammonium fluoride as an electrolyte, wherein the alcohol aqueous solution of ammonium fluoride 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 anodization is performed for 0.8 h under a bias voltage of 40 V, and 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) The TNT electrode substrate obtained in step (1) was used as the working electrode, the platinum sheet was used as the counter electrode, and the silver nitrate solution with a concentration of 0.07 mol / L was used as the electrolyte. The electrodeposition method was used at a current density of 2 mA cm -2 Silver was deposited for 8 min under the conditions of , and then washed with deionized water to obtain an Ag / TNT electrode;

[0073] (3) Spray 0.35 mL of a 0.1% anionic ionomer solution (Fumion FAA-3 produced by Fumasep Germany, solvent: N-methylpyrrolidone) onto the surface of the Ag / TNT electrode (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 anionic ionomer-modified silver-based electrode.

[0074] Example 4

[0075] This embodiment provides a method for preparing an anionic ionomer-modified silver-based electrode, which is different from Embodiment 1 only in 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 is different from Embodiment 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, which is different from Embodiment 1 only in 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, which is different from Embodiment 1 only in 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, which is different from Embodiment 1 only in 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 is different from Embodiment 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, which is different from Embodiment 1 only in that the deposition time of the electrodeposition method is 10 minutes.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing a silver-based electrode, which is different from Example 1 only in that step (3) is not performed, and the silver-based electrode is an Ag / TNT electrode.

[0090] Electroreduction CO2 activity evaluation experiment:

[0091] The activity evaluation experiment was carried out in a self-designed gas-solid electrochemical reaction cell. The reaction gas passed through the electrode surface of the cathode chamber at one time (the electrodes provided in Examples 1-10 and Comparative Example 1 were 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 KOH solution with a concentration of 1 mol / L was introduced into the anode chamber at a flow rate of 20 mL / min, and the counter electrode was nickel foam; the yin and yang chambers were separated by an anion exchange membrane. The test temperature of the reaction was 25 ° C, and the test pressure was one atmosphere. The electrochemical reactions were all carried out using an electrochemical workstation, and the products at different bias voltages were determined by gas chromatography and the Faraday efficiency of the products was calculated.

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

[0093] Under the preferred bias voltage (-2.7 V) for electrochemical reduction of CO2, the same test method as in Example 1 was used to conduct an activity evaluation experiment on the electrodes provided in Examples 2-10 and Comparative Example 1, and the Faraday efficiency and current density of CO and H2 were measured. The results are shown in Table 1. Taking Example 1, Examples 4-6 and Comparative Example 1 as examples, the results are shown in Table 1. Figure 2 As shown, from Figure 2 It can be seen that by adjusting the modified concentration of the anionic ionomer solution, the synthesis gas ratio (CO / H2) can be regulated in a wide range, thereby meeting the needs of preparing synthesis gas. 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] From the data in Table 1, we can see the following points:

[0098] (1) From the data of Examples 1-6, it can be seen that the anionic ionomer-modified silver-based electrode provided by the present invention is used in the electrochemical reduction of CO2 process. Under the optimal conditions, the current density reaches 21.23 mA / cm 2 The above indicates that the reaction activity is relatively high, wherein the Faraday efficiency of CO is above 75.30%, and the Faraday efficiency of H2 is below 21.98%, indicating that the CO selectivity is relatively high;

[0099] Furthermore, by comparing Example 1, Examples 4-6 and Comparative Example 1, it can be seen that the modification concentration of the anionic ionomer solution in Example 6 is too high, resulting in covering the active site Ag, making CO2 difficult to reduce, and the Faradaic efficiency of CO is reduced compared to Example 1; while in Comparative Example 1, no anionic ionomer modification was used, and both the Faradaic efficiency and current density of CO were significantly reduced compared to Example 1. It can be seen that the present invention can further improve the reaction activity and selectivity by using anionic ionomers for modification and controlling the modification concentration.

[0100] (2) From the data of Example 1 and Examples 7-8, it can be seen that in Example 7, due to the low concentration of the silver nitrate solution, the amount of Ag deposited is small, and the catalytic performance is reduced; in Example 8, due to the high concentration of the silver nitrate solution, the Ag nanoparticles are easily agglomerated, resulting in gas diffusion being blocked, so the Faraday efficiency of CO in Examples 7-8 is lower than that in Example 1. It can be seen that the present invention can further control the amount of Ag deposited by preferably controlling the concentration of the silver nitrate solution, thereby further improving the selectivity.

[0101] (3) From the data of Example 1 and Examples 9-10, it can be seen that in Example 9, due to the short electrodeposition time, the Ag loading is small, which affects the catalytic performance; in Example 10, due to the long electrodeposition time, Ag accumulation is easily formed, and even the TiO2 nanoarray is blocked. Therefore, the Faraday efficiency of CO in Examples 9-10 is lower than that in Example 1. It can be seen that the present invention can further regulate the deposition amount of Ag by preferably controlling the deposition time, thereby further improving the selectivity.

[0102] In summary, the electrode provided by the present invention has excellent CO2 electroreduction performance and high selectivity for CO, and can achieve regulation of the synthesis gas ratio in a wide range.

[0103] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope 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 comprises the following steps: (1) Using titanium substrate as working electrode, titanium dioxide nanotube array electrode was obtained by electrochemical anodization method, which was denoted as TNT electrode substrate; (2) using the TNT electrode substrate obtained in step (1) as a working electrode, and depositing silver by electrodeposition to obtain a TNT composite electrode deposited with Ag, which is referred to as an Ag / TNT electrode; (3) Spraying 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.

2. The preparation method according to claim 1, characterized in that: The titanium substrate in step (1) comprises titanium foam; Preferably, the counter electrode used in the electrochemical anodization method comprises a platinum sheet; Preferably, the electrolyte used in the electrochemical anodization method comprises an alcohol aqueous solution of ammonium fluoride; Preferably, the solvent of the alcohol aqueous solution of ammonium fluoride comprises ethylene glycol and deionized water; Preferably, the mass percentage of deionized water in the alcohol aqueous solution of ammonium fluoride is 2-5%; Preferably, the mass percentage of NH4F in the alcohol aqueous solution of ammonium fluoride is 0.5-1.5%; Preferably, the bias voltage used in the electrochemical anodization method is 30-50V; Preferably, the oxidation time adopted in the electrochemical anodization method is 0.75-2h.

3. The preparation method according to claim 1 or 2, characterized in that: After the electrochemical anodization method in step (1), washing, drying and annealing are performed in sequence to obtain a TNT electrode substrate; Preferably, the washing solution used in step (1) comprises ethanol; Preferably, the annealing temperature is 350-550°C; Preferably, the annealing time is 1-2 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The counter electrode used in the electrodeposition method in step (2) comprises a platinum sheet; Preferably, the electrolyte used in the electrodeposition method comprises a silver nitrate solution; Preferably, the concentration of the silver nitrate solution is 0.05-0.1 mol / L; Preferably, the deposition time used in the electrodeposition method is 1-8 min; Preferably, the current density used in the electrodeposition method is 1-10 mA·cm -2 .

5. The preparation method according to any one of claims 1 to 4, characterized in that: After the deposition in step (2) is completed, cleaning is performed to obtain an Ag / TNT electrode; Preferably, the washing solution used in step (2) comprises deionized water.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The anionic ionomer in step (3) comprises a polyaromatic polymer having an ether bond in the main chain and a quaternary ammonium group; Preferably, the anionic ionomer comprises Fumion FAA-3; Preferably, the solvent of the anionic ionomer solution comprises N-methylpyrrolidone; Preferably, the mass concentration of the anionic ionomer solution is 0.05%-5%.

7. The preparation method according to any one of claims 1 to 6, characterized in that: After the spraying in step (3), vacuum drying is also performed.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) using titanium foam as a working electrode, a platinum sheet as a counter electrode, and an alcohol aqueous solution of ammonium fluoride as an electrolyte, electrochemically anodizing for 0.75-2 h at a bias voltage of 30-50 V, then washing and drying in sequence, and then annealing at 350-550° C. for 1-2 h 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 -2 Silver is deposited for 1-8 min under the conditions of , and then washed to obtain an Ag / TNT electrode; (3) spraying an anionic ionomer solution with a mass concentration of 0.05%-5% on the surface of the Ag / TNT electrode obtained in step (2), and then vacuum drying to complete the preparation of the anionic ionomer modified silver-based electrode, wherein the anionic ionomer includes Fumion FAA-3, and the solvent of the anionic ionomer solution is N-methylpyrrolidone.

9. An anionic ionomer modified silver-based electrode, characterized in that: The anionic ionomer-modified silver-based electrode is obtained by the preparation method of the anionic ionomer-modified silver-based electrode according to any one of claims 1 to 8.

10. A use of the anionic ionomer modified silver-based electrode as claimed in claim 9, characterized in that: The anionic ionomer-modified silver-based electrode is used for the electroreduction of carbon dioxide.

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