Ag@AgCl / Cu2O double-shell structure nanowire catalyst, preparation method thereof, electrode and preparation method thereof, and application

Abstract

The application relates to the technical field of electrocatalysis, in particular to an Ag@AgCl / Cu2O double-shell structure nanowire catalyst, a preparation method thereof, an electrode and a preparation method thereof and application. The preparation method of the Ag@AgCl / Cu2O double-shell structure nanowire catalyst comprises the following steps: 1) uniformly mixing sodium chloride, ferric nitrate, polyvinylpyrrolidone and silver nitrate in ethylene glycol, reacting at 120-140 DEG C for 20-50 min, and obtaining a suspension; 2) uniformly mixing the suspension prepared in the step 1) with copper acetate and polyvinylpyrrolidone in ethylene glycol, then reacting at 120-140 DEG C, then uniformly mixing with copper chloride, and reacting at 120-140 DEG C, and then carrying out solid-liquid separation. The Ag@AgCl / Cu2O double-shell structure nanowire material prepared by the application can be widely used in the field of electrochemical energy storage devices for electro-reducing carbon dioxide.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, specifically to an Ag@AgCl / Cu2O double-shell nanowire catalyst, its preparation method, its electrode and its preparation method, and its applications. Background Technology

[0002] Due to accelerated global industrialization and a slow increase in the total population, carbon dioxide (CO2) emissions continue to rise, exacerbating climate change through the greenhouse effect. Converting carbon dioxide into high-value-added chemicals for reuse is a highly effective and cost-efficient solution.

[0003] Electrocatalytic carbon dioxide reduction can convert CO2 into carbon-containing chemicals in one step using electrical energy at ambient temperature and pressure. It boasts advantages such as mild reaction conditions, controllable products, and simple equipment, making it one of the most promising CO2 conversion technologies. HCOOH, as a product of electrocatalytic carbon dioxide reduction, is easy to separate and store and is environmentally friendly, making it suitable for the chemical industry and currently a highly commercially valuable product.

[0004] Chinese invention patent application publication number CN104034775A discloses a method for preparing polypyrrole / silver chloride core-shell structured nanowires. The polypyrrole / silver chloride core-shell structured nanowires have a three-layer structure. The first layer is a smooth and uniform silver nanowire with a diameter of 20-30 nanometers. The second layer is silver chloride particles tightly wrapped around the surface of the silver nanowires. The third layer is polypyrrole electrodeposited on the surface of the silver chloride core-shell structured nanowires. The method for preparing polypyrrole / silver chloride core-shell structured nanowires includes the following steps: (1) Preparation of silver nanowires: The ethylene glycol solution of polyvinylpyrrolidone is heated to 150-160℃. After 5-10 min, an ethylene glycol solution of nitrate is added to it. Then, a 0.25-0.1M NaCl solution is added. The reaction is carried out at 150-160℃ for 10-20 min. The whole process requires stirring. The product is first washed three times by centrifugation with acetone and then washed three times by centrifugation with distilled water to obtain silver nanowires. (2) Preparation of silver chloride nanowires: The silver nanowires prepared in step (1) were added to a 0.05-0.15M NaCl solution, and then an iron sheet treated with dilute hydrochloric acid was immersed in it. After the reaction was carried out at 20-35℃ for 30-75h, the iron sheet was removed. The product was washed three times by centrifugation with ethanol and distilled water respectively to obtain silver chloride nanowires; (3) Preparation of polypyrrole / silver chloride core-shell structure nanowires: Polypyrrole was wrapped on a glassy carbon electrode modified with silver chloride nanowires. Using the thin film as a reference electrode, a three-electrode system consisting of a platinum auxiliary electrode and a glassy carbon electrode modified with silver chloride nanowires was prepared by cyclic voltammetry in 10-15 mM pyrrole and 0.1-0.15 M NaClO4 solutions. The voltage range was from -0.6 V to 0.8 V, the scan rate was 0.05-0.1 V / s, and 2-20 cycles were performed to obtain polypyrrole / silver chloride core-shell nanowires. The resulting electrode is a polypyrrole / silver chloride core-shell nanowire modified electrode.

[0005] However, the raw materials required for the above preparation methods are complex, and the core-shell structure generation process is complex and difficult to control. Summary of the Invention

[0006] One of the objectives of this invention is to provide a simple method for preparing Ag@AgCl / Cu2O double-shell nanowire catalyst and the catalyst obtained therefrom.

[0007] The second objective of this invention is to provide the above-mentioned Ag@AgCl / Cu2O double-shell nanowire electrode and its preparation method.

[0008] A third objective of this invention is to provide applications for the above-mentioned Ag@AgCl / Cu2O double-shell nanowire catalyst.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing an Ag@AgCl / Cu2O double-shell nanowire catalyst includes the following steps:

[0011] 1) Mix sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate evenly in ethylene glycol and react at 120-140℃ for 20-50 min to obtain a suspension;

[0012] 2) Mix the suspension obtained in step 1) with copper acetate and polyvinylpyrrolidone in ethylene glycol until homogeneous, then react at 120-140℃ for 20-30 min. Then add copper chloride and mix until homogeneous, and react at 120-140℃ for 30-50 min. Separate the solid and liquid components to obtain the final product.

[0013] In step 1), the sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate are mixed evenly in ethylene glycol by adding the ethylene glycol solutions of sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate to ethylene glycol and mixing them evenly.

[0014] When adding the above solutions to ethylene glycol, the amount of ethylene glycol used is 800 mL for every 10-15 g of ferric nitrate. Before adding the solutions to the ethylene glycol, heat it to remove water from the solvent. The heating temperature is 120-140℃, and the heating time is 20-40 minutes.

[0015] In step 1), the concentration of the sodium chloride in the ethylene glycol solution is 12-14 g / L.

[0016] In step 1), the concentration of the ethylene glycol solution of polyvinylpyrrolidone (the first polyvinylpyrrolidone solution) is 40-50 g / L.

[0017] In step 1), the concentration of the ethylene glycol solution of ferric nitrate is 10-15 g / L.

[0018] In step 1), the concentration of the ethylene glycol solution of silver nitrate is 40-50 g / L.

[0019] In step 2), mixing the suspension with copper acetate and polyvinylpyrrolidone in ethylene glycol means mixing the suspension with the copper acetate solution and the ethylene glycol solution of polyvinylpyrrolidone. When adding copper chloride, an ethylene glycol solution of copper chloride is added.

[0020] In step 2), the concentration of the copper acetate in the ethylene glycol solution is 10⁻¹² g / L (measured as copper acetate monohydrate).

[0021] In step 2), the concentration of the ethylene glycol solution of polyvinylpyrrolidone (the second polyvinylpyrrolidone solution) is 40-50 g / L.

[0022] In step 2), the concentration of the ethylene glycol solution of copper chloride is 0.2-0.3 g / L.

[0023] In step 2), the amount of suspension used is 15-20 mL of suspension for every 0.1-0.12 g of copper acetate monohydrate.

[0024] In step 2), the solid-liquid separation is centrifugal separation.

[0025] An Ag@AgCl / Cu2O double-shell nanowire catalyst prepared by the above method.

[0026] A method for preparing an Ag@AgCl / Cu2O double-shell nanowire electrode includes the following steps:

[0027] 1) Sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate are mixed evenly in ethylene glycol and reacted at 120-140℃ for 1-5 hours to obtain a suspension;

[0028] 2) Mix the suspension obtained in step 1) with copper acetate and polyvinylpyrrolidone in ethylene glycol, and then react at 120-140℃ for 20-30 min. Then add copper chloride and mix well, and react at 120-140℃ for 30-50 min. Separate the solid and liquid to obtain the catalyst.

[0029] 3) Mix the catalyst obtained in step 2) with isopropanol and water evenly, then add the binder and mix evenly to obtain a slurry;

[0030] 4) The slurry obtained in step 3) is dropped onto the surface of carbon paper and dried by infrared drying to obtain the final product.

[0031] In step 1), the sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate are mixed evenly in ethylene glycol by adding the ethylene glycol solutions of sodium chloride, ferric nitrate, polyvinylpyrrolidone, and silver nitrate to ethylene glycol and mixing them evenly.

[0032] When adding the above solutions to ethylene glycol, the amount of ethylene glycol used is 200-2000 mL for every 10-15 g of ferric nitrate, preferably 200-1000 mL for every 10-15 g of ferric nitrate. More preferably, 800 mL of ethylene glycol is used for every 10-15 g of ferric nitrate. Before adding the above solutions to the ethylene glycol, heat the solution to remove water. The heating temperature is 120-140°C, and the heating time is 20-40 minutes.

[0033] In step 1), the concentration of the sodium chloride in the ethylene glycol solution is 5-25 g / L, preferably 10-15 g / L, and more preferably 12-14 g / L.

[0034] In step 1), the concentration of the ethylene glycol solution of polyvinylpyrrolidone (the first polyvinylpyrrolidone solution) is 40-80 g / L, preferably 40-56 g / L.

[0035] In step 1), the concentration of the ethylene glycol solution of ferric nitrate is 10-50 g / L, preferably 10-30 g / L, and more preferably 10-15 g / L.

[0036] In step 1), the concentration of the ethylene glycol solution of silver nitrate is 40-80 g / L, preferably 40-56 g / L.

[0037] In step 1), the reaction time at 120-140℃ is preferably 3-5 hours.

[0038] In step 2), mixing the suspension with copper acetate and polyvinylpyrrolidone in ethylene glycol means mixing the suspension with the copper acetate solution and the ethylene glycol solution of polyvinylpyrrolidone. When adding copper chloride, an ethylene glycol solution of copper chloride is added.

[0039] In step 2), the concentration of the ethylene glycol solution of copper acetate is 10-50 g / L, preferably 10-30 g / L, and more preferably 10-12 g / L. (Measured as copper acetate monohydrate)

[0040] In step 2), the concentration of the ethylene glycol solution of polyvinylpyrrolidone (the second polyvinylpyrrolidone solution) is 40-50 g / L.

[0041] In step 2), the concentration of the ethylene glycol solution of copper chloride is 0.2-0.3 g / L.

[0042] In step 2), the amount of suspension used is 10-50 mL of suspension for every 0.1-0.12 g of copper acetate monohydrate. Preferably, it is 10-20 mL of suspension, and more preferably, it is 15-20 mL of suspension.

[0043] In step 2), the solid-liquid separation is centrifugal separation.

[0044] In step 3), the amount of isopropanol used is 700-800 μL of isopropanol for every 5-10 mg of catalyst.

[0045] In step 3), the amount of water used is 150-200 μL of water for every 5-10 mg of catalyst.

[0046] In step 3), the catalyst is mixed with isopropanol and water until homogeneous, and then ultrasonically treated for 20-40 minutes. After adding the binder, the mixture is mixed until homogeneous, and then ultrasonically treated for 15-30 minutes.

[0047] Step 4) involves adding 100 μL of slurry in two separate drops to a 1 cm depth. 2On the area.

[0048] An Ag@AgCl / Cu2O double-shell nanowire electrode prepared by the above method.

[0049] Application of the above-mentioned Ag@AgCl / Cu2O double-shell nanowire catalyst in the electrocatalytic reduction of carbon dioxide.

[0050] Beneficial effects:

[0051] The Ag@AgCl / Cu2O double-shell nanowire material prepared by this invention allows for adjustment of the Cu2O and AgCl shell ratio by varying the amount of added copper chloride. With an adjustable ratio, the optimized Cu2O:AgCl feed ratio of the Ag@AgCl / Cu2O double-shell nanowire catalyst exhibits very high reactivity, achieving a balance between promoting carbon dioxide reduction and inhibiting hydrogen evolution. The Ag@AgCl / Cu2O double-shell nanowire material prepared by this method produces formic acid as its main product in the electrocatalytic carbon dioxide reduction process. Formic acid has considerable economic value, is easily separated and extracted from the electrolyte, and achieves high current density and product conversion rate at a relatively low reduction potential, demonstrating significant potential for industrial application and wide applicability in electrochemical energy storage devices for electroreduced carbon dioxide.

[0052] This invention synthesizes cuprous oxide / silver chloride nanowires using surface adsorption and in-situ oxidation methods. By controlling the amount of copper chloride added, Ag@AgCl / Cu2O double-shell nanowires with different AgCl / Cu2O ratios are prepared. Some samples achieve a Faraday efficiency of 96.7% for HCOOH at -0.9 V vs RHE potential, and the highest partial current density of HCOOH reaches -138 mA cm⁻¹. -2 . Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the preparation route in Example 1 of the present invention;

[0054] Figure 2 The image shows a scanning electron microscope (SEM) image of the silver nanowires prepared in Example 1 of this invention.

[0055] Figure 3 This is a scanning electron microscope (SEM) image of the Ag@AgCl / Cu2O double-shell nanowire catalyst sample prepared in Example 1 of the present invention.

[0056] Figure 4 This is a scanning electron microscope (SEM) image of the Ag@AgCl / Cu2O double-shell nanowire catalyst sample prepared in Example 2 of the present invention.

[0057] Figure 5 This is a scanning electron microscope (SEM) image of the Ag@AgCl / Cu2O double-shell nanowire catalyst sample prepared in Example 3 of the present invention.

[0058] Figure 6 The XRD patterns of the Ag@AgCl / Cu2O double-shell nanowire catalyst samples prepared in Examples 1, 2, and 3 of this invention are shown.

[0059] Figure 7 The LSV images are of the Ag@AgCl / Cu2O double-shell nanowire catalyst samples prepared in Examples 1, 2 and 3 of this invention.

[0060] Figure 8 This is a Faraday efficiency diagram of the electrocatalytic carbon dioxide reduction products of the Ag@AgCl / Cu2O double-shell nanowire catalyst sample prepared in Example 2 of the present invention.

[0061] Figure 9 The partial current density diagrams of the HCOOH products of the Ag@AgCl / Cu2O double-shell nanowire catalyst samples prepared in Examples 1, 2 and 3 of this invention are shown.

[0062] Figure 10 The AC impedance diagrams are shown for the Ag@AgCl / Cu2O double-shell nanowire catalyst samples prepared in Examples 1, 2 and 3 of this invention.

[0063] Figure 11 The Teffer slope diagrams are shown for the Ag@AgCl / Cu2O double-shell nanowire catalyst samples prepared in Examples 1, 2 and 3 of this invention.

[0064] Figure 12 The image shows the electroreduction stability curve of the Ag@AgCl / Cu2O double-shell nanowire catalyst sample prepared in Example 2 of this invention. Detailed Implementation

[0065] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved easier to understand, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0066] Example 1

[0067] like Figure 1 The preparation method of the Ag@AgCl / Cu2O double-shell nanowire electrode in this embodiment includes the following steps:

[0068] 1) Add 0.525g of polyvinylpyrrolidone (Mw=1300000) to 12.5mL of ethylene glycol, heat and stir until completely dissolved, and then cool to room temperature to obtain the first polyvinylpyrrolidone solution.

[0069] Weigh 0.257g of sodium chloride and add it to 20mL of ethylene glycol. Sonicate the solution until it is completely dissolved to obtain a sodium chloride solution.

[0070] Weigh 0.135g of ferric nitrate nonahydrate and add it to 10mL of ethylene glycol. Sonicate until completely dissolved to obtain ferric nitrate solution.

[0071] Add 80 mL of ethylene glycol to a three-necked flask and heat it in an oil bath to 130 °C for 30 min while stirring to remove water from the solvent.

[0072] Add 0.525g of silver nitrate to 12.5mL of ethylene glycol solution and sonicate until completely dissolved to obtain a silver nitrate solution.

[0073] 0.1 mL of sodium chloride solution, 0.05 mL of ferric nitrate solution, 10.38 mL of polyvinylpyrrolidone solution, and 10.38 mL of silver nitrate solution were slowly added dropwise to a three-necked flask. The mixture was then stirred in an oil bath at 130 °C for 4 h and cooled to room temperature to obtain an ethylene glycol suspension containing silver nanowire products.

[0074] 2) Weigh 0.119g of polyvinylpyrrolidone and add it to 27.5mL of ethylene glycol solution. Stir until completely dissolved to obtain a second polyvinylpyrrolidone solution.

[0075] Weigh 0.113 g of copper acetate monohydrate and dissolve it in 10 mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper acetate solution.

[0076] Weigh 0.00075 g of copper chloride and dissolve it in 3.05 mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper chloride solution.

[0077] Take 17.5 mL of the silver nanowire suspension prepared in step 1) and add it back into the three-necked flask. Add the second polyvinylpyrrolidone solution and copper acetate solution to the three-necked flask in sequence. After stirring evenly, purge with argon gas for 30 min to remove oxygen from the system.

[0078] The reaction was carried out in a sealed three-necked flask heated to 130℃ in an oil bath for 25 min, then copper chloride solution was added and reacted for 40 min. The resulting solution was purified by centrifugation and finally dispersed in ethanol to obtain the Ag@AgCl / Cu2O double-shell structured nanowire catalyst sample Ag@AgCl / Cu2O NWs-1.

[0079] 3) The Ag@AgCl / Cu2O NWs-1 catalyst sample obtained in step 2) was mixed with 7 mg catalyst sample + 760 μL isopropanol and 180 μL deionized water. After ultrasonic treatment for 30 min until completely dissolved, 60 μL Nafion was added as a binder, and ultrasonic treatment was carried out for about 20 min to obtain a uniformly mixed slurry.

[0080] 4) Take 100 μL of the well-mixed slurry from step 3) and drop it twice onto the center of the carbon paper at a position of 0.5*2 cm. 2 The area was determined and dried under infrared light to obtain Ag@AgCl / Cu2O double-shell nanowire electrodes.

[0081] Example 2

[0082] The preparation method of Ag@AgCl / Cu2O double-shell nanowires in this embodiment includes the following steps:

[0083] 1) Add 0.525g of polyvinylpyrrolidone (Mw=1300000) to 12.5mL of ethylene glycol, heat and stir until completely dissolved, and then cool to room temperature to obtain the first polyvinylpyrrolidone solution.

[0084] Weigh 0.257g of sodium chloride and add it to 20mL of ethylene glycol. Sonicate the solution until it is completely dissolved to obtain a sodium chloride solution.

[0085] Weigh 0.135g of ferric nitrate nonahydrate and add it to 10mL of ethylene glycol. Sonicate until completely dissolved to obtain ferric nitrate solution.

[0086] Add 80 mL of ethylene glycol to a three-necked flask and heat it in an oil bath to 130 °C for 30 min while stirring to remove water from the solvent.

[0087] Add 0.525g of silver nitrate to 12.5mL of ethylene glycol solution and sonicate until completely dissolved to obtain a silver nitrate solution.

[0088] 0.1 mL of sodium chloride solution, 0.05 mL of ferric nitrate solution, 10.38 mL of polyvinylpyrrolidone solution, and 10.38 mL of silver nitrate solution were slowly added dropwise to a three-necked flask. The mixture was then stirred in an oil bath at 130 °C for 4 h and cooled to room temperature to obtain an ethylene glycol suspension containing silver nanowire products.

[0089] 2) Weigh 0.119g of polyvinylpyrrolidone and add it to 27.5mL of ethylene glycol solution. Stir until completely dissolved to obtain a second polyvinylpyrrolidone solution.

[0090] Weigh 0.113 g of copper acetate monohydrate and dissolve it in 10 mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper acetate solution.

[0091] Weigh 0.00455g of copper chloride and dissolve it in 3.05mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper chloride solution.

[0092] Take 17.5 mL of the silver nanowire suspension prepared in step 1) and add it back into the three-necked flask. Add the second polyvinylpyrrolidone solution and copper acetate solution to the three-necked flask in sequence. After stirring evenly, purge with argon gas for 30 min to remove oxygen from the system.

[0093] The reaction was carried out in a sealed three-necked flask heated to 130℃ in an oil bath for 25 min, then copper chloride solution was added and reacted for 40 min. The resulting solution was purified by centrifugation and finally dispersed in ethanol to obtain the Ag@AgCl / Cu2O double-shell structured nanowire catalyst sample Ag@AgCl / Cu2O NWs-2.

[0094] 3) The Ag@AgCl / Cu2O NWs-1 catalyst sample obtained in step 2) was mixed with 7 mg catalyst sample + 760 μL isopropanol and 180 μL deionized water. After ultrasonic treatment for 30 min until completely dissolved, 60 μL Nafion was added as a binder, and ultrasonic treatment was carried out for about 20 min to obtain a uniformly mixed slurry.

[0095] 4) Take 100 μL of the well-mixed slurry from step 3) and drop it twice onto the center of the carbon paper at a position of 0.5*2 cm. 2 The area was determined and dried under infrared light to obtain Ag@AgCl / Cu2O double-shell nanowire electrodes.

[0096] Example 3

[0097] The preparation method of Ag@AgCl / Cu2O double-shell nanowires in this embodiment includes the following steps:

[0098] 1) Add 0.525g of polyvinylpyrrolidone (Mw=1300000) to 12.5mL of ethylene glycol, heat and stir until completely dissolved, and then cool to room temperature to obtain the first polyvinylpyrrolidone solution.

[0099] Weigh 0.257g of sodium chloride and add it to 20mL of ethylene glycol. Sonicate the solution until it is completely dissolved to obtain a sodium chloride solution.

[0100] Weigh 0.135g of ferric nitrate nonahydrate and add it to 10mL of ethylene glycol. Sonicate until completely dissolved to obtain ferric nitrate solution.

[0101] Add 80 mL of ethylene glycol to a three-necked flask and heat it in an oil bath to 130 °C for 30 min while stirring to remove water from the solvent.

[0102] Add 0.525g of silver nitrate to 12.5mL of ethylene glycol solution and sonicate until completely dissolved to obtain a silver nitrate solution.

[0103] 0.1 mL of sodium chloride solution, 0.05 mL of ferric nitrate solution, 10.38 mL of polyvinylpyrrolidone solution, and 10.38 mL of silver nitrate solution were slowly added dropwise to a three-necked flask. The mixture was then stirred in an oil bath at 130 °C for 4 h and cooled to room temperature to obtain an ethylene glycol suspension containing silver nanowire products.

[0104] 2) Weigh 0.119g of polyvinylpyrrolidone and add it to 27.5mL of ethylene glycol solution. Stir until completely dissolved to obtain a second polyvinylpyrrolidone solution.

[0105] Weigh 0.113 g of copper acetate monohydrate and dissolve it in 10 mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper acetate solution.

[0106] Weigh 0.0091 g of copper chloride and dissolve it in 3.05 mL of ethylene glycol solution. Stir until completely dissolved to obtain a copper chloride solution.

[0107] Take 17.5 mL of the silver nanowire suspension prepared in step 1) and add it back into the three-necked flask. Add the second polyvinylpyrrolidone solution and copper acetate solution to the three-necked flask in sequence. After stirring evenly, purge with argon gas for 30 min to remove oxygen from the system.

[0108] The reaction was carried out in a sealed three-necked flask heated to 130℃ in an oil bath for 25 min, then copper chloride solution was added and reacted for 40 min. The resulting solution was purified by centrifugation and finally dispersed in ethanol to obtain the Ag@AgCl / Cu2O double-shell structured nanowire catalyst sample Ag@AgCl / Cu2O NWs-3.

[0109] 3) The Ag@AgCl / Cu2O NWs-1 catalyst sample obtained in step 2) was mixed with 7 mg catalyst sample + 760 μL isopropanol and 180 μL deionized water. After ultrasonic treatment for 30 min until completely dissolved, 60 μL Nafion was added as a binder, and ultrasonic treatment was carried out for about 20 min to obtain a uniformly mixed slurry.

[0110] 4) Take 100 μL of the well-mixed slurry from step 3) and drop it twice onto the center of the carbon paper at a position of 0.5*2 cm. 2 The area was determined and dried under infrared light to obtain Ag@AgCl / Cu2O double-shell nanowire electrodes.

[0111] Experimental Example

[0112] (1) Morphological test

[0113] The nanowire suspension prepared in Example 1 was separated, dried, and analyzed by scanning electron microscopy (SEM). The results are as follows: Figure 2 As shown.

[0114] The Ag@AgCl / Cu2O NWs-1 catalyst sample prepared in Example 1 was analyzed by scanning electron microscopy (SEM). The results are as follows: Figure 3 As shown.

[0115] The Ag@AgCl / Cu2O NWs-2 catalyst sample prepared in Example 2 was analyzed by scanning electron microscopy (SEM). The results are as follows: Figure 4 As shown.

[0116] The Ag@AgCl / Cu2O NWs-3 catalyst sample prepared in Example 3 was analyzed by scanning electron microscopy (SEM). The results are as follows: Figure 5 As shown.

[0117] from Figure 2 It can be seen that the silver nanowires prepared by this invention have a relatively uniform diameter distribution and a large aspect ratio.

[0118] from Figure 3 It can be seen that the surface of the Ag@AgCl / Cu2O NWs-1 catalyst sample prepared in this invention is rough.

[0119] from Figure 4 It can be seen that the Ag@AgCl / Cu2O NWs-2 catalyst sample prepared in this invention has a high surface density.

[0120] from Figure 5 It can be seen that in the Ag@AgCl / Cu2O NWs-3 catalyst sample prepared in this invention, the amount of CuCl2·H2O added was 0.0091g. The relatively small amount of Cu2O adsorbed on the surface resulted in the nanowire surface not being completely covered. Furthermore, due to the large amount of CuCl2·H2O added, AgCl cubes were formed.

[0121] (2) XRD analysis

[0122] XRD comparative analysis was performed on the Ag@AgCl / Cu2O NWs catalysts from Examples 1, 2, and 3. The results are as follows: Figure 6 As shown.

[0123] from Figure 6It can be seen that the Ag@AgCl / Cu2O NWs catalyst samples with different addition ratios prepared in this invention exhibit three strong characteristic peaks, namely 2θ=38.11°, 2θ=36.44° and 2θ=32.24°. By comparing with the standard card in the XRD, it was found that the position of the diffraction peak of 2θ=38.11° is consistent with Ag-PDF#87-0597, while the position of the diffraction peak of 2θ=32.24° is consistent with AgCl-PDF#85-1355 and corresponds to the AgCl(200) crystal plane. Finally, the position of the diffraction peak of 2θ=36.44° corresponds to the card Cu2O-PDF#78-2076 and corresponds to the (111) crystal plane. Comparing samples with three different addition ratios, it was found that as the amount of CuCl2·H2O added increased, the intensity of the Cu2O diffraction peak remained basically unchanged, while the intensity of the AgCl diffraction peak gradually increased and the intensity of the Ag diffraction peak gradually decreased. This also indicates that the increase of CuCl2·H2O only affects the thickness of AgCl and does not affect the formation of Cu2O.

[0124] (3) Electroreduction of carbon dioxide

[0125] Electrodes prepared in Examples 1, 2, and 3 were used to perform electroreduction tests on carbon dioxide.

[0126] The electrocatalytic CO2RR test uses a gas diffusion electrode flow cell apparatus.

[0127] The counter electrode is a platinum sheet, the reference electrode is an Ag / AgCl electrode, and the above-mentioned electrode with carbon paper supported catalyst is used as the working electrode.

[0128] Experimental data processing: The potential was converted to a reversible hydrogen electrode (RHE) potential using the formula E(vs.RHE) = E(vs.Ag / AgCl) + 0.20V + 0.0591V × pH. The CO2 gas flow rate used for each sample test was 30 mL / min. -1 The constant voltage method was used to test at each potential for 1 hour, and the results were as follows: Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown.

[0129] from Figure 7 It can be seen that the Ag@AgCl / Cu2O NWs-2 and Ag@AgCl / Cu2O NWs-3 catalysts prepared in this invention have more positive onset potentials. At -1.5V vs. RHE potential, the Ag@AgCl / Cu2O NWs-2 sample exhibits a current density as high as 106.78 mA cm⁻¹. -2 .

[0130] from Figure 8 It can be seen that the Ag@AgCl / Cu2O NWs-2 catalyst prepared in this invention almost completely reduces CO2 to HCOOH, and the Faraday efficiency of HCOOH remains above 90% in a wide potential range of -0.7V to -1.2V vs. RHE.

[0131] from Figure 9 It can be seen that the Ag@AgCl / Cu2O NWs-2 catalyst prepared in this invention has the highest HCOOH fractional current density, with the highest current density reaching -135 mA cm⁻¹. -2 This indicates that the sample has excellent single-product catalytic activity.

[0132] from Figure 10 It can be seen that the proportion of Ag@AgCl / Cu2O NWs catalyst prepared in this invention has a certain influence on the conductivity of the catalyst itself.

[0133] from Figure 11 It can be seen that the Tafel slope fitting of the Ag@AgCl / Cu2O NWs-2 catalyst prepared in this invention is 1928.92 mV dec. -1 The value is the smallest compared to other samples, indicating that the catalyst has the fastest kinetics and the energy barrier that needs to be overcome for the reaction to occur. Therefore, the Ag@AgCl / Cu2O NWs-2 catalyst has the highest electrocatalytic activity for CO2 reduction.

[0134] from Figure 12 It can be seen that the Ag@AgCl / Cu2O NWs-2 catalyst prepared in this invention can maintain a current density of 120 mA cm⁻² at -1.0 V vs. RHE potential. -2 The Faraday efficiency of HCOOH decreases slightly after about 50 hours, but still remains above 90%.

[0135] The above experimental results show that the Ag@AgCl / Cu2O double-shell nanowire material prepared in this invention can control the coverage of the Cu2O shell on the surface of Ag@AgCl NWs and the thickness of the AgCl shell, thereby achieving high HCOOH selectivity in the electrocatalytic carbon dioxide reduction reaction.

[0136] The above descriptions are merely preferred embodiments and experimental examples of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing Ag@AgCl / Cu20 double-shell structure nanowire electrode, characterized in that, The method comprises the following steps: 1) uniformly mixing sodium chloride, ferric nitrate, polyvinylpyrrolidone and silver nitrate in ethylene glycol, and reacting at 120-140 ℃ for 1-5 h to obtain an ethylene glycol suspension containing silver nanowire product; 2) weighing 0.119 g of polyvinylpyrrolidone and adding it into 27.5 mL of ethylene glycol, and stirring until completely dissolved to obtain a polyvinylpyrrolidone solution; weighing 0.113 g of copper acetate monohydrate and dissolving it in 10 mL of ethylene glycol, and stirring until completely dissolved to obtain a copper acetate solution; weighing 0.00455 g of copper chloride and dissolving it in 3.05 mL of ethylene glycol, and stirring until completely dissolved to obtain a copper chloride solution; uniformly mixing the suspension obtained in step 1) with the copper acetate solution and the polyvinylpyrrolidone solution, and then reacting at 120-140 ℃ for 20-30 min, and then adding the copper chloride solution and uniformly mixing, and then reacting at 120-140 ℃ for 30-50 min, and then performing solid-liquid separation to obtain a catalyst; 3) uniformly mixing the catalyst obtained in step 2) with isopropyl alcohol and water, and then adding a binder and uniformly mixing to obtain a slurry; 4) dropping the slurry obtained in step 3) on the surface of carbon paper, and performing infrared drying to obtain the product; In step 2), the amount of the suspension is 15-20 mL for every 0.1-0.12 g of copper acetate monohydrate.

2. The method for preparing the Ag@AgCl / Cu2O double-shell nanowire electrode as described in claim 1, characterized in that, In step 1), the sodium chloride, ferric nitrate, polyvinylpyrrolidone and silver nitrate are uniformly mixed in ethylene glycol by adding ethylene glycol solutions of sodium chloride, ferric nitrate, polyvinylpyrrolidone and silver nitrate into ethylene glycol and uniformly mixing.

3. The method for preparing the Ag@AgCl / Cu2O double-shell nanowire electrode as described in claim 2, characterized in that, In step 1), the concentration of the ethylene glycol solution of sodium chloride is 12-14 g / L.

4. The method for preparing the Ag@AgCl / Cu2O double-shell nanowire electrode as described in claim 1, characterized in that, In step 4) 80-120 μL of the slurry was added dropwise in two portions over a 1 cm 2 area of the carbon paper surface.

5. Application of the Ag@AgCl / Cu2O double-shell structure nanowire electrode prepared by the preparation method of claim 1 in electrocatalytic reduction of carbon dioxide.

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