A method for preparing silver-copper alloy nanoparticles

Abstract

The application provides a preparation method of silver-copper alloy nanoparticles, which comprises the following steps: mixing and dissolving silver nitrate, copper acetate monohydrate, polyvinylpyrrolidone and ethylene glycol, obtaining a mixed solution after carbon dioxide gas blowing treatment, carrying out rapid cooling treatment in a cold water bath after heating treatment of the mixed solution through an oil bath, carrying out centrifugal separation, carrying out vacuum oven drying treatment, preparing an electrode from the obtained solid product, and carrying out electrochemical reduction treatment in an electrochemical cell to obtain a target product. The application realizes the successful preparation of silver-copper alloy nanoparticles, and the silver-copper alloy nanoparticles with adjustable silver / copper molar ratio can be obtained by changing the feeding ratio of silver nitrate and copper acetate monohydrate, so that the silver-copper alloy nanoparticles can be applied to the electrocatalytic carbon dioxide reduction reaction, and the catalytic performance with high selectivity to high-value-added products can be obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of catalyst material preparation, and particularly relates to a preparation method of silver-copper alloy nanoparticles. BACKGROUND

[0002] Under the urgent demand of developing new, efficient and clean energy utilization methods, electrochemical carbon dioxide reduction reaction (ECO2RR, electrochemical CO2 reduction reaction) has been widely studied because it can use electrochemical method to reduce carbon dioxide into carbon monoxide, methane, methanol, ethylene, ethanol and other high value-added energy chemical products under the action of catalyst. Among them, copper catalyst can realize the reduction of carbon dioxide into alcohol or hydrocarbon with higher value-added products due to its strong binding strength with most ECO2RR intermediates (such as *CO intermediate), but copper catalyst also faces the problem of poor product selectivity in ECO2RR application (Chem, 2018, 4(8): 1809-1831.). In contrast, silver catalyst can usually obtain good CO product selectivity in ECO2RR due to its weak binding strength with ECO2RR intermediates (such as *CO intermediate), but it is difficult to reduce carbon dioxide into products with higher value-added (Nat. Commun., 2021, 12, 660.). Alloying can change the electronic structure of the material, and can obtain unique properties different from the properties of each component by comprehensively combining the properties of each component (Nat. Commun., 2021, 12, 1449). SUMMARY

[0003] To overcome the problems in the prior art, the purpose of the present application is to provide a preparation method of silver-copper alloy nanoparticles, which comprehensively combines the properties of copper and silver in ECO2RR, uses the prepared silver-copper alloy nanoparticles as catalyst, and obtains ECO2RR performance with high selectivity for high value-added products (such as ethanol, ethylene, etc.).

[0004] To achieve the above purpose, the present application adopts the following scheme:

[0005] A preparation method of silver-copper alloy nanoparticles, comprising the following steps:

[0006] Dissolve silver salt, copper salt and polyvinylpyrrolidone in ethylene glycol, and obtain a mixed solution by blowing carbon dioxide gas;

[0007] After heating treatment and cooling, the mixed solution is subjected to centrifugal separation and drying, and the dried solid product is prepared into a silver-copper electrode, which is subjected to electrochemical reduction treatment in an electrochemical cell to obtain silver-copper alloy nanoparticles.

[0008] Further, the silver salt is silver nitrate.

[0009] Further, the copper salt is copper acetate monohydrate.

[0010] Further, the mass ratio of silver nitrate to copper acetate monohydrate is 1:(0.2-10).

[0011] Further, the mass ratio of silver nitrate to polyvinylpyrrolidone is 1:(0.5-2), and the average molecular weight of the polyvinylpyrrolidone is 10000-100000.

[0012] Further, the dosage ratio of silver nitrate to ethylene glycol is 1mg:50mL.

[0013] Further, the temperature of the heating treatment is 150-200℃, and the time is 5-20min.

[0014] Further, the temperature of the cooling is 15-25℃, and the time is 2-5min.

[0015] Further, the silver-copper electrode is prepared by the following process: the specific process of preparing the dried solid product into an electrode is as follows: the dried solid product is mixed with a Nafion solution in isopropyl alcohol, and after ultrasonic treatment, a mixed slurry is obtained, the mixed slurry is dropped on a glassy carbon electrode with a diameter of 3mm to obtain the silver-copper electrode; wherein the dosage ratio of the dried solid product, the Nafion solution and the isopropyl alcohol is 1mg:(2-10)μL:(0.1-0.5)mL.

[0016] Further, the specific process of the electrochemical reduction treatment in the electrochemical cell is as follows: the electrochemical cell is an H-shaped electrolytic cell with two chambers, the two chambers are separated by an ion exchange membrane or a proton exchange membrane, the electrolyte is a carbon dioxide gas saturated 0.5mol / L potassium bicarbonate aqueous solution, the working electrode is a silver-copper electrode, the reference electrode is an Ag / AgCl electrode, the counter electrode is a platinum sheet electrode, the electrochemical reduction potential is-1.8--2.6V vs.Ag / AgCl, and the electrochemical reduction treatment time is 15-60min.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The present application first prepares a mixed solution of silver salt, copper salt and polyvinylpyrrolidone in ethylene glycol, and then cools the solution after heating treatment. The obtained product is centrifuged and dried to prepare silver-copper electrodes, which are subjected to electrochemical reduction treatment in an electrochemical cell to obtain silver-copper alloy nanoparticles. The present application uses ethylene glycol, which has viscosity and weak reducing property, as a reducing agent. First, the silver salt and the copper salt are reduced to small elemental silver and elemental copper at high temperature. Under the action of polyvinylpyrrolidone as a surfactant and binder, the small elemental silver and elemental copper interleave and nucleate to gradually grow into nanoparticles. Finally, the silver-copper nanoparticles obtained are reconstructed into silver-copper alloy nanoparticles at a reduction potential by in-situ structure reconstruction triggered by electrochemical reduction treatment. In addition, the electrochemical reduction treatment can also reduce the oxidation layer on the surface of the silver-copper nanoparticles during the centrifugation and drying process to avoid the presence of silver oxide or copper oxide in the final silver-copper alloy. The prepared silver-copper alloy nanoparticles effectively combine the characteristics of copper catalyst (strong binding strength with most ECO2RR intermediates) and silver catalyst (weak binding strength with ECO2RR intermediates) in ECO2RR, and the silver-copper alloy nanoparticles with adjustable silver / copper molar ratio can be obtained by changing the feeding ratio of silver salt and copper salt, thereby effectively regulating the binding strength of the silver-copper alloy nanoparticles with ECO2RR intermediates and obtaining different product selectivity in ECO2RR.

[0019] Further, the purging of carbon dioxide, argon or nitrogen can remove dissolved oxygen in the reaction system to avoid oxidation of elemental silver and copper.

[0020] Further, rapid cooling after the end of the heat treatment can quickly terminate the reduction reaction and prevent uneven distribution of silver and copper phases in the particles caused by excessive heat treatment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A transmission electron microscope photo of the silver-copper alloy nanoparticles obtained in Example 1 of the present application.

[0022] Figure 2 A high-resolution transmission electron microscope photo of the silver-copper alloy nanoparticles obtained in Example 1 of the present application.

[0023] Figure 3 The silver / copper molar ratio in the silver-copper alloy nanoparticles obtained in Example 1 of the present application.

[0024] Figure 4 The electrocatalytic carbon dioxide reduction performance of the silver-copper alloy nanoparticles obtained in Example 1 of the present application at a potential of -0.9 V vs. RHE.

[0025] Figure 5Transmission electron microscope image of silver copper alloy nanoparticles obtained in Example 2 of the present invention.

[0026] Figure 6 High resolution transmission electron microscope image of silver copper alloy nanoparticles obtained in Example 2 of the present invention.

[0027] Figure 7 Silver / copper molar ratio in silver copper alloy nanoparticles obtained in Example 2 of the present invention.

[0028] Figure 8 Electrocatalytic carbon dioxide reduction performance at -1.1 V vs. RHE potential of silver copper alloy nanoparticles obtained in Example 2 of the present invention.

[0029] Figure 9 Transmission electron microscope image of silver copper alloy nanoparticles obtained in Example 3 of the present invention.

[0030] Figure 10 High resolution transmission electron microscope image of silver copper alloy nanoparticles obtained in Example 3 of the present invention.

[0031] Figure 11 Silver / copper molar ratio in silver copper alloy nanoparticles obtained in Example 3 of the present invention.

[0032] Figure 12 Electrocatalytic carbon dioxide reduction performance at -1.1 V vs. RHE potential of silver copper alloy nanoparticles obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further illustrated by the following examples.

[0034] The present invention can be better understood in accordance with the following examples. However, it is to be understood that the particular materials, conditions, and results described in the examples are not to be construed as limiting the scope of the invention as described in the claims.

[0035] The method for preparing silver copper alloy nanoparticles of the present invention specifically comprises the following steps:

[0036] S1, dissolve A mg silver nitrate, B mg copper acetate monohydrate and 0.5-2 g polyvinylpyrrolidone (average molecular weight 10000-100000) in 50 mL ethylene glycol in a round bottom flask, wherein A:B = 1:(0.2-10); use carbon dioxide, argon or nitrogen gas with a gas flow rate of 50-200 mL / min for purging treatment, and the treatment time is not less than 30 min, to obtain a mixed solution.

[0037] S2. Place the mixed solution obtained in step S1 into an oil bath and heat it for 5 to 20 minutes at a temperature of 150 to 200°C.

[0038] S3. The mixed solution obtained by heating in the oil bath in step S2 is rapidly cooled in a cold water bath at 15-25°C for 2-10 minutes, then centrifuged at 5000-8000 r / min for 5-10 minutes. The solid product is collected and dried in a vacuum oven at 60-100°C for 8-12 hours.

[0039] S4. Take C mg of the dried solid product obtained in step S3, mix it with D μL of Nafion solution in E mL of isopropanol, and sonicate for at least 10 min to obtain a mixed slurry, wherein C:D:E = 1:(2~10):(0.1~0.5). Take an appropriate amount (3 μL) of the mixed slurry and drop it onto a glassy carbon electrode. After air drying, a silver-copper electrode is obtained. Electrochemically reduce the electrode in an electrochemical cell to obtain the target product, silver-copper alloy nanoparticles. In the electrochemical reduction treatment, the electrochemical cell is an H-type electrolytic cell with two chambers separated by an ion exchange membrane or a proton exchange membrane. The electrolyte is a potassium bicarbonate aqueous solution saturated with carbon dioxide gas at a concentration of 0.1~1 mol / L. The working electrode is the silver-copper electrode prepared in step S4, the reference electrode is an Ag / AgCl electrode, the counter electrode is a platinum sheet electrode, and the electrochemical reduction potential is -1.8~-2.6V. vs. Ag / AgCl, electrochemical reduction treatment time is 15-60 min.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and several preferred embodiments.

[0041] Example 1

[0042] (1) Dissolve 25.48 mg silver nitrate, 119.79 mg copper acetate monohydrate and 1.06 g polyvinylpyrrolidone (average molecular weight 58000) in 50 mL ethylene glycol and place in a round bottom flask; purge with carbon dioxide gas at a flow rate of 100 mL / min for 40 min to obtain a mixed solution.

[0043] (2) The mixed solution obtained in step (1) is placed in an oil bath and heated for 10 minutes at a temperature of 180°C.

[0044] (3) The mixed solution obtained by heating in the oil bath in step (3) is rapidly cooled in a cold water bath at 15°C for 3 min, then centrifuged at 5000 r / min for 10 min, and the solid product is collected and dried in a vacuum oven at 60°C for 12 h.

[0045] (4) Take 10 mg of the dried solid product obtained in step S3, mix with 30 μL of Nafion solution in 1.6 mL of isopropanol, and ultrasonically treat for 10 min to obtain a mixed slurry. Take 3 μL of the mixed slurry and drop onto a glassy carbon electrode with a diameter of 3 mm, and naturally air dry to obtain an electrode. Electrochemically reduce in an electrochemical cell to obtain the target product silver-copper alloy nanoparticles, wherein in the electrochemical reduction, the electrochemical cell is an H-type electrolytic cell with two chambers separated by an ion exchange membrane or a proton exchange membrane, the electrolyte is a 0.5 mol / L aqueous potassium bicarbonate solution saturated with carbon dioxide gas, the working electrode is the electrode prepared in step (4), the reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. The electrochemical reduction potential is -2.0 V vs. Ag / AgCl, and the electrochemical reduction time is 30 min.

[0046] (5) Take the silver-copper alloy obtained in step (4) as the working electrode nanoparticles, use a sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane, the electrolyte is a 0.5 mol / L aqueous potassium bicarbonate solution saturated with carbon dioxide gas, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. Apply a potential of -0.9 V vs. RHE for 30 min, and then use gas chromatography and liquid chromatography to detect the gaseous and liquid products generated in the electrolytic cell, and calculate the Faraday efficiency to evaluate the selectivity of the catalyst.

[0047] Figure 1 The transmission electron microscope photograph of the silver-copper alloy nanoparticles obtained in Example 1 of the present application shows that the obtained silver-copper alloy nanoparticles have a diameter of about 100 nm.

[0048] Figure 2 The high-resolution transmission electron microscope photograph of the silver-copper alloy nanoparticles obtained in Example 1 of the present application shows that the lattice spacing of the obtained silver-copper alloy nanoparticles is 0.218 nm, proving the successful preparation of the silver-copper alloy.

[0049] Figure 3 The silver / copper molar ratio in the silver-copper alloy nanoparticles obtained in Example 1 of the present application is shown to be 54:46.

[0050] Figure 4 The electrocatalytic carbon dioxide reduction performance of the silver-copper alloy nanoparticles obtained in Example 1 of the present application at a potential of -0.9 V vs. RHE is shown in FIG. 1, which shows that the silver-copper alloy nanoparticles obtained in Example 1 exhibit good selectivity for reducing carbon dioxide to alcohols at a voltage of -0.9 V vs. RHE. Figure 4

[0051] Example 2 ​

[0052] (1) 59.45 mg of silver nitrate, 79.86 mg of copper acetate monohydrate and 1.06 g of polyvinylpyrrolidone (average molecular weight 58000) were dissolved in 50 mL of ethylene glycol in a round-bottom flask; the mixed solution was obtained by purging with argon gas at a flow rate of 100 mL / min for 35 min.

[0053] (2) The mixed solution obtained in step (1) was heated in an oil bath at a temperature of 200℃ for 6 min.

[0054] (3) The mixed solution obtained by heating in the oil bath in step (3) was rapidly cooled in a cold water bath at 24℃ for 5 min, and then centrifuged at a speed of 8000 r / min for 10 min, and the solid product was collected and dried in a vacuum oven at 80℃ for 8 h.

[0055] (4) 10 mg of the dried solid product obtained in step S3 was mixed with 30 μL of Nafion solution in 1.6 mL of isopropanol, and a mixed slurry was obtained after ultrasonic treatment for 15 min, 3 μL of the mixed slurry was dropped on a glassy carbon electrode with a diameter of 3 mm, and then naturally dried to obtain an electrode; the target product silver-copper alloy nanoparticles were obtained by electrochemical reduction treatment in an electrochemical cell, wherein in the electrochemical reduction treatment, the electrochemical cell was a H-type electrolytic cell with two chambers separated by an ion exchange membrane, the electrolyte was a 0.5 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas, the working electrode was the electrode prepared in step (4), the reference electrode was an Ag / AgCl electrode, the counter electrode was a platinum sheet electrode, the electrochemical reduction potential was -2.6 V vs. Ag / AgCl, and the electrochemical reduction treatment time was 15 min.

[0056] (5) The silver-copper alloy obtained in step (4) was used as the working electrode, a sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane was used, the electrolyte was a 0.5 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas, the reference electrode was an Ag / AgCl electrode, the counter electrode was a platinum sheet electrode, and the applied potential was -1.1 V vs. RHE, after 30 min, the gas and liquid products generated in the electrolytic cell were detected by gas chromatography and liquid chromatography, and the Faraday efficiency was calculated to evaluate the selectivity of the catalyst.

[0057] Figure 5 The transmission electron microscope photograph of the silver-copper alloy nanoparticles obtained in Example 2 of the present application shows that the obtained silver-copper alloy nanoparticles have a diameter of about 100 nm.

[0058] Figure 6A high-resolution transmission electron microscope image of the silver-copper alloy nanoparticles obtained in Example 2 of the present application shows that the lattice spacing of the obtained silver-copper alloy nanoparticles is 0.229 nm, proving the successful preparation of the silver-copper alloy.

[0059] Figure 7 The silver / copper molar ratio in the silver-copper alloy nanoparticles obtained in Example 2 of the present application is shown to be 71:29.

[0060] Figure 8 The electrocatalytic carbon dioxide reduction performance of the silver-copper alloy nanoparticles obtained in Example 2 of the present application at a potential of -1.1 V vs. RHE is shown in FIG. 2. Figure 8 As shown in FIG. 2, the silver-copper alloy nanoparticles obtained in Example 2 exhibit good selectivity for reducing carbon dioxide into hydrocarbons at a voltage of -1.1 V vs. RHE.

[0061] Example 3

[0062] (1) 84.94 mg of silver nitrate, 49.91 mg of copper acetate monohydrate, and 1.2 g of polyvinylpyrrolidone (average molecular weight 10000) were dissolved in 50 mL of ethylene glycol in a round-bottom flask; nitrogen gas with a gas flow rate of 200 mL / min was used for purging treatment for 32 min to obtain a mixed solution.

[0063] (2) The mixed solution obtained in step (1) was placed in an oil bath for heating treatment, and the oil bath was heated to a temperature of 150°C for 20 min.

[0064] (3) The mixed solution obtained by oil bath heating treatment in step (3) was rapidly cooled in a cold water bath at 25°C for 10 min, and then subjected to centrifugal separation at a speed of 8000 r / min for 10 min. The solid product was collected and dried in a vacuum oven at 100°C for 8 h.

[0065] (4) 10 mg of the dried solid product obtained in step S3 was mixed with 30 μL of Nafion solution in 1.6 mL of isopropanol, and the mixture was ultrasonically treated for 10 min to obtain a mixed slurry. 3 μL of the mixed slurry was dropped onto a glassy carbon electrode with a diameter of 3 mm, and then naturally dried to obtain an electrode. The target product, silver-copper alloy nanoparticles, was obtained by electrochemical reduction treatment in an electrochemical cell. In the electrochemical reduction treatment, the electrochemical cell was a H-type electrolytic cell with two chambers separated by an ion exchange membrane. The electrolyte was a carbon dioxide gas-saturated 0.5 mol / L potassium bicarbonate aqueous solution. The working electrode was the electrode prepared in step (4). The reference electrode was an Ag / AgCl electrode, and the counter electrode was a platinum sheet electrode. The electrochemical reduction potential was -2.0 V vs. Ag / AgCl, and the electrochemical reduction treatment time was 30 min.

[0066] (5) using the silver copper alloy obtained in step (4) as a working electrode, using a sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane, using a carbon dioxide gas-saturated 0.5 mol / L potassium bicarbonate aqueous solution as an electrolyte, using an Ag / AgCl electrode as a reference electrode, using a platinum sheet electrode as a counter electrode, applying a potential of -1.1 V vs. RHE, after 30 min, using gas chromatography and liquid chromatography to detect the gaseous products and liquid products generated in the electrolytic cell, and calculating the Faraday efficiency to evaluate the selectivity of the catalyst.

[0067] Figure 9 A transmission electron microscope photograph of the silver copper alloy nanoparticles obtained in Example 3 of the present application shows that the obtained silver copper alloy nanoparticles have a diameter of about 100 nm.

[0068] Figure 10 A high-resolution transmission electron microscope photograph of the silver copper alloy nanoparticles obtained in Example 3 of the present application shows that the obtained silver copper alloy nanoparticles have a lattice spacing of 0.236 nm, proving the successful preparation of the silver copper alloy.

[0069] Figure 11 The silver / copper molar ratio in the silver copper alloy nanoparticles obtained in Example 3 of the present application is shown to be 98:2.

[0070] Figure 12 The electrocatalytic carbon dioxide reduction performance of the silver copper alloy nanoparticles obtained in Example 3 of the present application at a potential of -1.1 V vs. RHE is shown in FIG. 2. Figure 12 As shown in FIG. 2, the silver copper alloy nanoparticles obtained in Example 3 exhibit good selectivity for reducing carbon dioxide to carbon monoxide at a voltage of -1.1 V vs. RHE.

[0071] Example 4

[0072] (1) 84.94 mg of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone (average molecular weight 100000) were dissolved in 50 mL of ethylene glycol in a round-bottom flask; nitrogen gas with a gas flow rate of 100 mL / min was used for purging treatment for 30 min to obtain a mixed solution. The amount ratio of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone was 1 mg:0.2 mg:1 g.

[0073] (2) The mixed solution obtained in step (1) was placed in an oil bath for heating treatment, and the oil bath was heated to a temperature of 160°C for 15 min.

[0074] (3) The mixed solution obtained by heating treatment in the oil bath kettle in step (3) is rapidly cooled in a cold water bath at 15°C for 10 min, and then subjected to centrifugal separation at a rotation speed of 5000 r / min for 5 min. The solid product is collected and dried in a vacuum oven at 80°C for 10 h.

[0075] (4) 10 mg of the dried solid product obtained in step S3 is mixed with 60 μL of a Nafion solution in 1 mL of isopropanol, and a mixed slurry is obtained after ultrasonic treatment for 10 min. 3 μL of the mixed slurry is dropped on a glassy carbon electrode with a diameter of 3 mm, and the electrode is obtained after natural air drying. The target product, silver-copper alloy nanoparticles, is obtained by electrochemical reduction treatment in an electrochemical cell. In the electrochemical reduction treatment, the electrochemical cell is an H-type electrolytic cell with two chambers separated by an ion exchange membrane. The electrolyte is a 0.3 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas. The working electrode is the electrode prepared in step (4). The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. The electrochemical reduction potential is -2.0 V vs. Ag / AgCl, and the electrochemical reduction treatment time is 40 min.

[0076] (5) The silver-copper alloy obtained in step (4) is used as the working electrode, and a sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane is used. The electrolyte is a 0.5 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas. The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. The applied potential is -1.1 V vs. RHE. After 30 min, the gas and liquid products generated in the electrolytic cell are detected by gas chromatography and liquid chromatography, and the Faraday efficiency is calculated to evaluate the selectivity of the catalyst.

[0077] Example 5

[0078] (1) 84.94 mg of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone (average molecular weight 50000) are dissolved in 50 mL of ethylene glycol in a round-bottom flask. Carbon dioxide gas is blown at a flow rate of 50 mL / min for 35 min to obtain a mixed solution. The amount ratio of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone is 1 mg: 10 mg: 2 g.

[0079] (2) The mixed solution obtained in step (1) is placed in an oil bath kettle for heating treatment. The oil bath kettle is heated at a temperature of 170°C for 10 min.

[0080] (3) The mixed solution obtained by heating treatment in the oil bath kettle in step (3) is rapidly cooled in a cold water bath at 25℃ for 10 min, and then subjected to centrifugal separation at a rotation speed of 8000 r / min for 5 min. The solid product is collected and dried in a vacuum oven at 60℃ for 12 h.

[0081] (4) 10 mg of the dried solid product obtained in step S3 is mixed with 100 μL of a Nafion solution in 5 mL of isopropanol, and a mixed slurry is obtained after ultrasonic treatment for 10 min. 3 μL of the mixed slurry is dropped on a glassy carbon electrode with a diameter of 3 mm, and then naturally dried to obtain an electrode. The target product, silver-copper alloy nanoparticles, is obtained by electrochemical reduction treatment in an electrochemical cell. In the electrochemical reduction treatment, the electrochemical cell is an H-type electrolytic cell with two chambers separated by an ion exchange membrane. The electrolyte is a 1 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas. The working electrode is the electrode prepared in step (4). The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. The electrochemical reduction potential is -2.6 V vs. Ag / AgCl, and the electrochemical reduction treatment time is 60 min.

[0082] (5) The silver-copper alloy obtained in step (4) is used as the working electrode, and a sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane is used. The electrolyte is a 0.5 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas. The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum sheet electrode. The applied potential is -1.1 V vs. RHE. After 30 min, the gas and liquid products generated in the electrolytic cell are detected by gas chromatography and liquid chromatography, and the Faraday efficiency is calculated to evaluate the selectivity of the catalyst.

[0083] Example 6

[0084] (1) 84.94 mg of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone (average molecular weight 30000) are dissolved in 50 mL of ethylene glycol in a round-bottom flask. Argon gas with a gas flow rate of 200 mL / min is used for purging treatment for 40 min to obtain a mixed solution. The amount ratio of silver nitrate, copper acetate monohydrate, and polyvinylpyrrolidone is 1 mg:6 mg:0.5 g.

[0085] (2) The mixed solution obtained in step (1) is placed in an oil bath kettle for heating treatment. The oil bath kettle is heated to a temperature of 200℃ for 5 min.

[0086] (3) The mixed solution obtained by heating treatment in the oil bath kettle of step (3) is rapidly cooled in a cold water bath at 20℃ for 10 min, and then centrifuged at a speed of 7000 r / min for 8 min. The solid product is collected and dried in a vacuum oven at 60℃ for 11 h.

[0087] (4) 10 mg of the dried solid product obtained in step S3 is mixed with 20 μL of Nafion solution in 3 mL of isopropanol, and a mixed slurry is obtained after ultrasonic treatment for 10 min. 3 μL of the mixed slurry is dropped on a glassy carbon electrode with a diameter of 3 mm, and then naturally dried to obtain an electrode. The target product, silver-copper alloy nanoparticles, is obtained by electrochemical reduction treatment in an electrochemical cell. In the electrochemical reduction treatment, the electrochemical cell is an H-type electrolytic cell with two chambers separated by an ion exchange membrane. The electrolyte is a carbon dioxide gas-saturated 0.1 mol / L potassium bicarbonate aqueous solution. The working electrode is the electrode prepared in step (4). The reference electrode is an Ag / AgCl electrode. The counter electrode is a platinum sheet electrode. The electrochemical reduction potential is -1.8 V vs. Ag / AgCl. The electrochemical reduction treatment time is 15 min.

[0088] (5) The silver-copper alloy obtained in step (4) is used as the working electrode. A sealed H-type electrolytic cell with two chambers separated by an ion exchange membrane is used. The electrolyte is a carbon dioxide gas-saturated 0.5 mol / L potassium bicarbonate aqueous solution. The reference electrode is an Ag / AgCl electrode. The counter electrode is a platinum sheet electrode. The applied potential is -1.1 V vs. RHE. After 30 min, the gas and liquid products generated in the electrolytic cell are detected by gas chromatography and liquid chromatography, and the Faraday efficiency is calculated to evaluate the selectivity of the catalyst.

[0089] The method of the present application realizes the successful preparation of silver-copper alloy nanoparticles, and by changing the feeding ratio (A:B) of silver nitrate and copper acetate monohydrate in step S1, silver-copper alloy nanoparticles with adjustable silver / copper molar ratio can be obtained. The prepared silver-copper alloy nanoparticles effectively integrate the characteristics of copper catalysts (with strong binding strength to most ECO2RR reaction intermediates) and silver catalysts (with weak binding strength to ECO2RR reaction intermediates) in ECO2RR. By obtaining silver-copper alloy nanoparticles with adjustable silver / copper molar ratio, the binding strength of silver-copper alloy nanoparticles to ECO2RR reaction intermediates can be effectively regulated, thus obtaining different product selectivity in ECO2RR (as shown in Figure 4 、 Figure 8 and Figure 12 ).

[0090] It is to be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" can include a combination of two or more components, and the term "an element" can include comparable reference to a plurality of elements. Also, as used in this specification and the appended claims, the term "or" as used in the context of "A / B or C" means any of the following: A; B; or C. Also, the term "comprising" as used in the claims should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Rather, the term "comprising" is to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof.

[0091] It should be noted that the above description and the preferred embodiments are not to be construed as limiting the design idea of the present application. Those skilled in the art can modify and change the technical idea of the present application in various forms, and such modifications and changes should be understood as falling within the scope of the present application.

Claims

1. A method for preparing silver-copper alloy nanoparticles, characterized in that, Includes the following steps: Silver salt, copper salt and polyvinylpyrrolidone were dissolved in ethylene glycol and purged with carbon dioxide gas to obtain a mixed solution; The mixed solution was heated and then cooled, then centrifuged and dried. The dried solid product was used to prepare a silver-copper electrode, which was then subjected to electrochemical reduction in an electrochemical cell to obtain silver-copper alloy nanoparticles. The silver salt is silver nitrate, and the copper salt is copper acetate monohydrate. The mass ratio of silver nitrate to copper acetate monohydrate is 1:(0.2~10). The mass ratio of silver nitrate to polyvinylpyrrolidone is 1:(0.5~2), and the average molecular weight of polyvinylpyrrolidone is 10000~100000; The cooling temperature is 15–25 °C, and the time is 2–5 min; The specific process of electrochemical reduction treatment in the electrochemical cell is as follows: the electrochemical cell is an H-type electrolytic cell with two chambers, which are separated by an ion exchange membrane or a proton exchange membrane. The electrolyte is a 0.5 mol / L potassium bicarbonate aqueous solution saturated with carbon dioxide gas. The working electrode is a silver-copper electrode, the reference electrode is an Ag / AgCl electrode, the counter electrode is a platinum sheet electrode, the electrochemical reduction potential is -1.8 to -2.6 V vs. Ag / AgCl, and the electrochemical reduction treatment time is 15 to 60 min.

2. The method for preparing silver-copper alloy nanoparticles according to claim 1, characterized in that, The ratio of silver nitrate to ethylene glycol is 1 mg: 50 mL.

3. The method for preparing silver-copper alloy nanoparticles according to claim 1, characterized in that, The heat treatment temperature is 150-200 ℃, and the time is 5-20 min.

4. The method for preparing silver-copper alloy nanoparticles according to claim 1, characterized in that, The silver-copper electrode is prepared through the following process: The specific process of preparing the electrode from the dried solid product is as follows: The dried solid product is mixed with Nafion solution in isopropanol, and after ultrasonic treatment, a mixed slurry is obtained. The mixed slurry is then dropped onto a glassy carbon electrode with a diameter of 3 mm to obtain the silver-copper electrode. The ratio of the dried solid product, Nafion solution, and isopropanol is [ratio to be inserted here]. .

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