Preparation method of copper-based composite catalyst and application of copper-based composite catalyst in CO2 electrocatalytic reduction

Abstract

The invention provides a preparation method of a copper-based composite catalyst and application of the copper-based composite catalyst in CO2 electrocatalytic reduction, and relates to the technical field of catalysts. The composite catalyst is prepared by utilizing the reduction effect of a reducing agent and the electromagnetic coupling effect to promote the combination of rare earth elements and copper elements to form a co-melt and then performing electrochemical activation treatment. Two different rare earth elements (Eu and La) are modified in the catalyst, so that the optimization effect of the catalyst on a CO2 electrocatalytic reduction reaction path can be enhanced by utilizing the synergistic effect of the metal elements, the catalyst can obtain higher C2 + product selectivity, and the Faraday efficiency is improved. According to the composite catalyst prepared through the preparation method, under the large current density, the Faraday efficiency of ECO2RR exceeds 96%, the Faraday efficiency of a C2 + product reaches up to 82.2%, the Faraday efficiency of a carbon-containing product exceeds 96%, and the catalytic performance is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a preparation method of a copper-based composite catalyst and application thereof in CO2 electrocatalytic reduction. BACKGROUND

[0002] The acceleration of industrialization process worldwide has led to a sharp increase in CO2 emissions, causing the greenhouse effect to intensify year by year and the climate problem to become increasingly serious. Therefore, in response to the call of the "double carbon target", it is urgent to achieve CO2 emission reduction. Carbon dioxide electrocatalytic reduction (ECO2RR) is attracting attention because it can convert CO2 into high-value carbon-based fuels (such as methanol, methane, ethylene, ethane, etc.) under mild conditions. This technology can be driven by renewable electricity and has the dual potential of realizing CO2 utilization and renewable energy storage, becoming one of the key driving technologies to achieve the "double carbon target". However, the inherent high stability of CO2 molecules, the complexity of multi-electron transfer processes, and the competition of hydrogen evolution reaction, have resulted in difficulties and challenges such as high activation energy, poor product selectivity, and low faradic efficiency in ECO2RR.

[0003] Copper-based catalysts are considered to be ideal materials for ECO2RR to synthesize C 2+ products due to their moderate adsorption energy for CO. However, traditional copper-based catalysts have drawbacks such as wide product distribution, strong hydrogen evolution side reaction, and active site deactivation. For example, the CH4 selectivity of the copper-based catalyst reported in patent CN119592981A is generally less than 60%, and the partial current density is still lower than the industrialization demand. The introduction of rare earth elements provides a new way to optimize the performance of copper-based catalysts. Rare earth metals (such as praseodymium, cerium, lanthanum, etc.) can regulate the interface environment of copper-based catalysts and improve the catalytic performance due to their unique electronic configuration and high oxygen affinity. However, existing technologies mainly focus on the doping modification of a single rare earth element. Due to the large difference in bonding characteristics of different rare earth metals, it is difficult to form a co-melting catalyst material, and the potential of multi-rare earth element gradient modification of copper-based catalysts has not been fully explored.

[0004] Therefore, it is necessary to design an improved preparation method of a copper-based composite catalyst and application thereof in CO2 electrocatalytic reduction to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a copper-based composite catalyst and application thereof in CO2 electrocatalytic reduction.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a preparation method of a copper-based composite catalyst, comprising the following steps:

[0007] S1, dissolving copper salt, first rare earth salt and second rare earth salt in water to obtain a metal salt solution;

[0008] S2, adding a reducing agent solution to the metal salt solution in a magnetic field environment, and performing electrochemical activation treatment after reaction to obtain a copper-based composite catalyst.

[0009] Preferably, in step S1, the first rare earth salt and the second rare earth salt are any one of lanthanum, cerium, europium and scandium, and the rare earth elements in the first rare earth salt and the second rare earth salt are different.

[0010] Preferably, the molar ratio of the rare earth element in the first rare earth salt to the rare earth element in the second rare earth salt is 1:1-1:10, and the content of copper element in the metal salt solution is 50-90% of the total amount of all metals.

[0011] Preferably, in step S2, the field strength of the magnetic field is 0.1-0.3T.

[0012] Preferably, in step S2, the dropping speed of the reducing agent solution added to the metal salt solution is 100 mL / min.

[0013] Preferably, in step S2, the electrochemical activation treatment is performed in the following manner: after the copper-based composite catalyst is dispersed in a dispersant, it is loaded on carbon paper to form a working electrode by using a spraying method, and then the sample is reduced in an electrolytic cell by using a cyclic voltammetry method, the electrolytic cell is a gas diffusion electrode, the electrolyte is 1 M KOH, the current range of the cyclic voltammetry method is -0.9~ -2.0 V vs. Ref., the cyclic number of the cyclic voltammetry method is 20 cycles, and the scanning speed is 100 mV / s.

[0014] In a second aspect, the present application provides a copper-based composite catalyst.

[0015] In a third aspect, the present application provides an application of a copper-based composite catalyst in CO2 electrocatalytic reduction, and the specific application method comprises the following steps: adjusting the current density to 100-600 mA / cm 2 .

[0016] In a fourth aspect, the present application provides an application of a copper-based composite catalyst in CO2 electrocatalytic reduction to prepare C 2+ products, characterized in that the C 2+ products include C3H7OH, C2H5OH and HCOOH.

[0017] The present application has the following beneficial effects:

[0018] 1. The preparation method of the copper-based composite catalyst provided by the application can utilize the synergistic effect between metal elements to enhance the optimization of the catalyst on the CO2 electrocatalytic reduction reaction path, which is conducive to obtaining higher C 2+ product selectivity and improving the faradic efficiency of the catalyst. The synergistic effect between metals is reflected in the synergistic change of the adsorption site and the adjustment of the reaction path, as well as the synergistic optimization of the adsorption intermediate adsorption energy and the reduction of the reaction energy barrier. The composite catalyst prepared by the above method has a faradic efficiency of ECO2RR of more than 96% at a large current density, a C 2+ product faradic efficiency of up to 82.2%, a carbon-containing product faradic efficiency of more than 96%, and excellent catalytic performance.

[0019] 2. The copper-based composite catalyst provided by the application has lower alternating current impedance than the copper-based catalyst modified by a single rare earth element, so that the catalyst can achieve a higher current density at the same potential during CO2 electrocatalytic reduction in a gas diffusion electrode, and the current density of the catalyst during CO2 electrocatalytic reduction can reach a large current density of 600 mA / cm 2 , a C 2+ product current density of 480 mA / cm 2 .

[0020] 3. The preparation method provided by the application can occur at room temperature, and the reaction conditions are mild and the equipment requirements are low. The catalyst preparation process is simple, convenient for large-scale production, and has the possibility of low-cost mass production. The rare earth metal selected by the application has excellent catalytic performance, and compared with the copper-based catalyst modified by a noble metal, it is more economical and has more industrial application possibilities. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The faradic efficiency distribution of the composite metal catalyst prepared in Examples 1 to 4 of the application for CO2 electrocatalytic reduction at different current densities is shown in the following table:

[0022] Figure 2 The faradic efficiency distribution of the composite metal catalyst prepared in Examples 1 to 4 of the application for C 2+ product at different current densities is shown in the following table:

[0023] Figure 3 The Nyquist diagram obtained by measuring the alternating current impedance of the composite metal catalyst prepared in Examples 1 to 4 of the application is shown in the following table:

[0024] Figure 4 The Nyquist diagram obtained by measuring the alternating current impedance of the composite metal catalyst prepared in Examples 2 and Comparative Examples 1 to 2 of the application is shown in the following table:

[0025] Figure 5 C 2+ Comparison of product current density;

[0026] Figure 6 Morphology characterization results of the composite metal catalyst prepared in the application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be described in detail below with reference to the drawings and specific embodiments.

[0028] It should also be noted that, in order not to obscure the application due to unnecessary details, only structures and / or processing steps closely related to the scheme of the application are shown in the drawings, and other details not closely related to the application are omitted.

[0029] In addition, it should also be noted that the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0030] In one aspect, the application provides a preparation method of a copper-based composite catalyst, comprising the following steps:

[0031] S1, dissolving a copper salt and a rare earth salt in water to prepare a metal salt solution;

[0032] S2, in a magnetic field environment, adding a reducing agent solution to the metal salt solution, under the reduction of the reducing agent, the metal salt in the metal salt solution is reduced to a solid powder, and the double rare earth elements are beneficial to combine with the transition metal copper element to form a eutectic body under the action of the magnetic field, and the obtained product is subjected to centrifugal washing, vacuum drying and electrochemical activation treatment to prepare a copper-based composite catalyst.

[0033] In some embodiments, in step S1, the rare earth salt is composed of a first rare earth salt and a second rare earth salt, both of which are soluble salts of rare earth elements such as lanthanum, cerium, europium and scandium, the content of copper element in the metal salt solution is 50-90% of the total amount of all metal elements in moles, the molar ratio of rare earth elements in the first rare earth salt to rare earth elements in the second rare earth salt is 1:1-1:10, the dissolution temperature is 25±5 ℃, and the addition amount of metal elements in deionized water is 5-6 mmol per 100 mL. In some specific embodiments, the copper salt, the first rare earth salt and the second rare earth salt are corresponding nitrate salts, such as Eu(NO3)3·6H2O for the first rare earth salt and La(NO3)3·6H2O for the second rare earth salt.

[0034] In some embodiments, in step S1, the temperature of the dissolving process is 25±5°C, and the amount of substance of all metal ions added per 100 mL of the metal salt solution is 5-6 mmol.

[0035] In some embodiments, in step S2, the reducing agent solution is obtained by dissolving a reducing agent in water, the reducing agent is sodium borohydride or ascorbic acid, and the amount of the reducing agent added is 2-3 times the total amount of moles of all metal elements in the metal salt solution, and the amount of sodium borohydride or ascorbic acid added per 100 mL of deionized water is 1-1.2 g.

[0036] In some embodiments, in step S2, the dropping speed of the reducing agent solution added to the metal salt solution is 100 mL / min.

[0037] In some embodiments, in step S2, the magnetic field strength is 0.1-0.3 T, and the magnetic field environment can be provided by a micro electromagnet or other means.

[0038] In some embodiments, in step S2, the temperature of the stirring process is 25°C, and the time is 5 h.

[0039] In some embodiments, in step S2, the number of centrifugal washing is 3-4 times, and deionized water and anhydrous ethanol are used for washing; the temperature of vacuum drying is 60°C, and the time is 12-24 h.

[0040] In some embodiments, in step S2, the electrochemical activation treatment is performed as follows: after the copper-based composite catalyst is dispersed in a dispersant, it is loaded on a carbon paper to form a working electrode by a spraying method, and the sample is reduced in an electrolytic cell by a cyclic voltammetry method, the electrolytic cell is a gas diffusion electrode flow cell, the electrolyte is 1 M KOH, the current range of the cyclic voltammetry method is -0.9~ -2.0 V vs. Ref., the number of cycles of the cyclic voltammetry method is 20, and the scanning speed is 100 mV / s. In the above process, by performing the electrochemical activation treatment, not only the surface passivation layer of the composite catalyst precursor can be removed, but also the surface structure and defects thereof can be adjusted to obtain a composite catalyst with high stability and high specific surface area.

[0041] On the other hand, the present invention also provides a method for applying the above-mentioned copper-based composite catalyst to the ECO2RR reaction, which can be carried out in an electrochemical activation device for the above-mentioned composite catalyst, and the current density of the reaction process is 100-600 mA / cm². 2 Exceeding industrial-grade current density of 200 mA / cm² 2 C can be prepared during the ECO2RR reaction. 2+ Product, C 2+ The products include C3H7OH, C2H5OH, HCOOH, etc.

[0042] The preparation method of the copper-based composite catalyst provided by the present invention and its application in the electrocatalytic reduction of CO2 are further illustrated below with reference to specific embodiments:

[0043] Example 1

[0044] This embodiment prepared a chemical formula Eu 0.05 La 0.05 Cu 0.9 The preparation method of the copper-based composite catalyst includes the following steps:

[0045] S1. Add 1.087 g Cu(NO3)2·6H2O crystals, 0.109 g Eu(NO3)3·6H2O crystals, and 0.109 g La(NO3)3·6H2O crystals to 80 mL of water and stir until homogeneous in a magnetic stirrer at 25 °C to obtain a metal salt solution containing the three metals.

[0046] S2. Add 1g of NaBH4 crystals to 50 mL of water and stir evenly in a magnetic stirrer at 25℃ to obtain a NaBH4 solution with a concentration of 0.02 g / mL. Adjust the stirring temperature to 25℃ and the magnetic field strength to 0.15T. Slowly add the NaBH4 solution to the metal salt solution, controlling the addition time to 1 min. After the NaBH4 solution is added, continue stirring for 5 h to allow the metal salt to be fully reduced and form a stable solid precipitate. Collect the precipitate and wash it 3-4 times by centrifugation with deionized water and anhydrous ethanol at 8000 rpm. Then dry it in a vacuum environment at 60℃ for 16 h.

[0047] S3. Add 10 mg of the dried sample obtained in step S2 to a mixture of 1.5 mL isopropanol and 10 µL Nafion 117 solution, and sonicate for 30 min to obtain a uniformly mixed suspension. Fill the suspension into a spray gun and spray it evenly onto 3 mm × 3 mm carbon paper, and then allow the carbon paper to dry.

[0048] The carbon paper coated with the sample is used as a working electrode to assemble a gas diffusion electrode, cyclic voltammetry is tested in a voltage range of -0.9 V vs. Ref. ~ -2.0 V vs. Ref., the catalyst surface is fully activated while reducing oxide impurities, and a composite catalyst with a Cu content of 90% is obtained, which can directly perform an ECO2RR reaction under original device conditions.

[0049] Example 2

[0050] In this embodiment, a copper-based composite catalyst with a chemical formula of Eu 0.1 La 0.1 Cu 0.8 is prepared, and the preparation method comprises the following steps:

[0051] S1, 0.966 g of Cu(NO3)2·6H2O crystals, 0.217 g of Eu(NO3)3·6H2O crystals, and 0.217 g of La(NO3)3·6H2O crystals are added to 85 mL of water, and the mixture is stirred uniformly in a 23°C constant-temperature magnetic stirrer to prepare a metal salt solution containing three kinds of metals;

[0052] S2, 1.05 g of NaBH4 crystals is added to 50 mL of water, and the mixture is stirred uniformly in a 23°C constant-temperature magnetic stirrer to obtain a NaBH4 solution with a concentration of 0.021 g / mL; the stirring temperature is maintained at 23°C, the magnetic field strength is 0.2T, the NaBH4 solution is slowly added to the metal salt solution, the addition time is controlled to be 0.8 min, and after the addition of the NaBH4 solution is completed, the stirring is continued for 5 h, so that the metal salt is fully reduced to form a stable solid precipitate; the precipitate is collected, washed with deionized water and anhydrous ethanol by centrifugation at a speed of 8000 rpm for 3-4 times, and then dried in a vacuum environment at 60°C for 12 h to prepare a copper-based composite catalyst;

[0053] S3, 10 mg of the dried sample obtained in step S2 is added to a mixed solution of 1.5 mL of isopropyl alcohol and 10 μL of Nafion117 solution, and ultrasonic treatment is performed for 30 min to obtain a uniformly mixed suspension; the suspension is filled into a spray gun, and the suspension is uniformly sprayed on a 3 mm×3 mm carbon paper through the spray gun, and then the carbon paper is dried;

[0054] The carbon paper coated with the sample is used as a working electrode to assemble a gas diffusion electrode, cyclic voltammetry is tested in a voltage range of -0.9 V vs. Ref. ~ -2.0 V vs. Ref., the catalyst surface is fully activated while reducing oxide impurities, and a composite catalyst with a Cu content of 80% is obtained.

[0055] Example 3

[0056] A copper-based composite catalyst with a chemical formula of Eu 0.15 La 0.15 Cu 0.7 The preparation method comprises the following steps:

[0057] S1, 0.846 g of Cu(NO3)2·6H2O crystals, 0.326 g of Eu(NO3)3·6H2O crystals, and 0.325 g of La(NO3)3·6H2O crystals are added to 85 mL of water, and the mixture is stirred uniformly in a 21°C constant-temperature magnetic stirrer to prepare a metal salt solution containing three kinds of metals;

[0058] S2, 1.1 g of NaBH4 crystals is added to 50 mL of water, and the mixture is stirred uniformly in a 21°C constant-temperature magnetic stirrer to obtain a NaBH4 solution with a concentration of 0.022 g / mL; the stirring temperature is maintained at 21°C, the magnetic field strength is 0.25T, the NaBH4 solution is slowly added to the metal salt solution, the addition time is controlled to be 0.9 min, and after the addition of the NaBH4 solution is completed, the stirring is continued for 5 h, so that the metal salt is fully reduced to form a stable solid precipitate; the precipitate is collected, washed with deionized water and anhydrous ethanol by centrifugation at a speed of 8000 rpm for 3-4 times, and then dried in a vacuum environment at 60°C for 14 h to prepare a copper-based composite catalyst;

[0059] S3, 10 mg of the dried sample obtained in step S2 is added to a mixed solution of 1.5 mL of isopropyl alcohol and 10 μL of Nafion117 solution, and ultrasonic treatment is performed for 30 min to obtain a uniformly mixed suspension; the above suspension is filled into a spray gun, and the suspension is uniformly sprayed on a 3 mm×3 mm carbon paper through the spray gun, and then the carbon paper is dried;

[0060] The carbon paper coated with the sample is used as a working electrode to assemble a gas diffusion electrode, and a cyclic voltammetry test is performed in a voltage range of -0.9 V vs. Ref. ~ -2.0 V vs. Ref. to fully activate the catalyst surface and reduce oxide impurities, thereby obtaining a composite catalyst with a Cu content of 70%.

[0061] Example 4

[0062] A copper-based composite catalyst with a chemical formula of Eu 0.2 La 0.2 Cu 0.6 The preparation method comprises the following steps:

[0063] S1, 0.725 g Cu(NO3)2·6H2O crystals, 0.435 g Eu(NO3)3·6H2O crystals, 0.434 g La(NO3)3·6H2O crystals were added into 85 mL water, and stirred uniformly in a constant-temperature magnetic stirrer at 27°C to prepare a metal salt solution containing three kinds of metals;

[0064] S2, 1.15 g NaBH4 crystals were added into 50 mL water, and stirred uniformly in a constant-temperature magnetic stirrer at 27°C to obtain a NaBH4 solution with a concentration of 0.023 g / mL; the stirring temperature was maintained at 27°C, the magnetic field strength was 0.1 T, the NaBH4 solution was slowly added into the metal salt solution, the addition time was controlled to be 1.1 min, and after the addition of the NaBH4 solution was completed, stirring was continued for 5 h to allow the metal salt to be fully reduced to form a stable solid precipitate; the precipitate was collected, washed with deionized water and anhydrous ethanol by centrifugation at a speed of 8000 rpm for 3-4 times, and then dried in a vacuum environment at 60°C for 18 h to prepare a copper-based composite catalyst;

[0065] S3, 10 mg of the dried sample obtained in step S2 was added into a mixed solution of 1.5 mL of isopropyl alcohol and 10 μL of Nafion117 solution, and ultrasonicated for 30 min to obtain a uniformly mixed suspension; the above suspension was filled into a spray gun, and the suspension was uniformly sprayed on a 3 mm x 3 mm carbon paper through the spray gun, and then the carbon paper was dried;

[0066] The carbon paper coated with the sample was used as a working electrode to assemble a gas diffusion electrode, and cyclic voltammetry test was performed in a voltage range of -0.9 V vs. Ref. ~ -2.0 V vs. Ref. to fully activate the catalyst surface and reduce oxide impurities, thereby obtaining a composite catalyst with a Cu content of 60%.

[0067] Comparative Example 1

[0068] The chemical formula of the composite catalyst prepared in this comparative example is Eu 0.2 Cu 0.8 The difference between Comparative Example 1 and Example 2 is only that in step S1, the metal salt solution contains only one rare earth element, and the metal salt solution is prepared as follows: 0.966 g of Cu(NO3)2·6H2O crystals and 0.434 g of Eu(NO3)3·6H2O crystals are added into 85 mL of water to prepare a catalyst with a Cu content of 80%, and the remaining experimental conditions are the same as those in Example 1, which will not be repeated here.

[0069] Comparative Example 2

[0070] The chemical formula of the composite catalyst prepared in this comparative example is La 0.2Cu 0.8 The difference between Comparative Example 2 and Example 2 is only that in step S1, the metal salt solution contains only one rare earth element, and the metal salt solution is prepared as follows: 0.966 g of Cu(NO3)2·6H2O crystals and 0.433 g of La(NO3)3·6H2O crystals are added to 85 mL of water to prepare a catalyst with a Cu content of 80%, and the remaining experimental conditions are the same as those of Example 1, which will not be repeated here.

[0071] The application of the composite catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 2 in the electrocatalytic reduction of CO2 is shown in Table 1, and the performance results at a current density of 500 mA / cm 2 2+ The ECO2RR reaction (electrochemical CO2 reduction reaction) selectivity of the composite catalyst prepared in Comparative Examples 1 and 2 is lower than that of the composite catalyst prepared in the examples, wherein the ECO2RR reaction selectivity of the composite catalyst prepared in Example 2 is as high as 96.1%, and the C

[0072] Table 1 Performance test results of different catalysts

[0073] Item ECO2RR reaction selectivity Hydrogen evolution reaction selectivity C 2+ product selectivity Example 1 92.6 9.7 79.5 Example 2 96.1 8.1 82.2 Example 3 90.8 10.2 70.4 Example 4 90.1 13.8 68.1 Comparative Example 1 85.9 17.0 58.8 Comparative Example 2 84.2 17.5 53.8

[0074] During the experiment, the application performance of the composite catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 2 in the gas diffusion electrode was also explored, which was carried out as follows: the electrochemical impedance of the composite catalyst was measured at a potential of -1.37 V vs. RHE, and the reaction was carried out at a current density of 100 mA / cm 2 , 200 mA / cm 2 , 300 mA / cm 2 , 400 mA / cm 2 , 500 mA / cm 2 and 600 mA / cm 2 , respectively, under the condition that the CO2 flow rate was controlled at 30 mL / min, the reaction temperature was controlled at 25℃, the electrolyte was 1 M KOH solution, the electrolyte was replaced every 2 h, the composition and content of the gaseous product were analyzed by gas chromatography, the composition and content of the liquid product were analyzed by nuclear magnetic resonance hydrogen spectrum, and the calculation method of the current density was the product of the current density and the corresponding product Faraday efficiency.

[0075] Specifically, the Faraday efficiency distribution results of the composite catalysts prepared in Examples 1 to 4 in the electrocatalytic reduction of CO2 at different current densities are shown in Table 2. Figure 1 ​As shown in FIG. (a) - FIG. (d) in the figure, Figure 1 correspond to examples 1 to 4 respectively, the results show that the highest C 2+ product faraday efficiency is higher than 70%, and at 500 mA / cm 2 and 600 mA / cm 2 high current density, the hydrogen evolution reaction selectivity is low. In addition, the composite metal catalysts prepared in examples 1 to 4 have higher C 2+ product faraday efficiency distribution under different current densities as shown in Figure 2 , Figure 2 correspond to examples 1 to 4 respectively, C 2+ product faraday efficiency is higher at high current density, and reaches the maximum at 500 mA / cm 2 or 600 mA / cm 2 , which indicates that the composite metal catalyst provided by the application has the advantage of producing C 2+ product at high current density.

[0076] The Nyquist diagram obtained by measuring the alternating current impedance of the composite catalyst prepared in examples 1 to 4 applied to the gas diffusion electrode is shown in Figure 3 , and the Nyquist diagram under the conditions of example 2 and comparative examples 1 to 2 is shown in Figure 4 , comparative analysis shows that the alternating current impedance of example 2 is much lower than that of comparative examples 1 and 2, which indicates that the composite metal catalyst provided by the application can effectively reduce the alternating current impedance, so that the same current density can be reached at a lower potential, and the energy consumption is effectively reduced. The C 2+ product current density of the composite metal catalyst prepared in example 2 and comparative examples 1 to 2 under different current densities is shown in Figure 5 , the results show that the current density of example 2 under each current density is higher than that of comparative examples 1 and 2, and the C 2+ product current density of example 2 reaches 479.9 mA / cm 2 at 600 mA / cm 2 , which has excellent performance. The morphology characterization results of the composite catalyst of example 2 are shown in Figure 6 , Figure 6 , FIG. (a) in the figure is a SEM image, Figure 6 , FIG. (b) is a TEM image, the results show that the morphology of the catalyst is uniform nanoparticles, and there are periodic parallel lattice stripes in the composite catalyst, Cu(111) surface is detected, which indicates the existence of single crystal copper structure.

[0077] The above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a copper-based composite catalyst, characterized in that, Includes the following steps: S1. Dissolve copper salt, first rare earth salt, and second rare earth salt in water to prepare a metal salt solution; S2. In a magnetic field environment, the reducing agent solution is added to the metal salt solution. After the reaction is completed, the copper-based composite catalyst is obtained by electrochemical activation treatment.

2. The preparation method according to claim 1, characterized in that, In step S1, the first rare earth salt and the second rare earth salt are any one of lanthanum, cerium, europium, and scandium, and the rare earth elements in the first rare earth salt and the second rare earth salt are different.

3. The preparation method according to claim 2, characterized in that, The molar ratio of rare earth elements in the first rare earth salt to that in the second rare earth salt is 1:1 to 1:10; the copper content in the metal salt solution is 50-90% of the total amount of all metals.

4. The preparation method according to claim 1, characterized in that, In step S2, the field strength of the magnetic field is 0.1-0.3T.

5. The preparation method according to claim 1, characterized in that, In step S2, the reducing agent solution is added to the metal salt solution at a dropping rate of 100 mL / min.

6. The preparation method according to claim 1, characterized in that, In step S2, the electrochemical activation treatment is carried out as follows: after dispersing the copper-based composite catalyst in a dispersant, it is loaded onto carbon paper by spraying to form a working electrode. The sample is reduced in an electrolytic cell using cyclic voltammetry. The electrolytic cell is a gas diffusion electrode, the electrolyte is 1 MKOH, the cyclic voltammetry current range is -0.9 to -2.0 V vs. Ref., the number of cyclic voltammetry cycles is 20, and the scan rate is 100 mV / s.

7. A copper-based composite catalyst, characterized in that, It is prepared by any one of claims 1-6.

8. The application of a copper-based composite catalyst according to any one of claims 1-6 in the electrocatalytic reduction of CO2.

9. A method for using a copper-based composite catalyst according to any one of claims 1-6 in the electrocatalytic reduction of CO2, characterized in that, The steps include: adjusting the current density to 100-600 mA / cm² in the CO2 electrocatalytic reduction device. 2 .

10. A copper-based composite catalyst according to any one of claims 1-6 for the electrocatalytic reduction of CO2 to prepare C 2+ The application of the product is characterized by, The C 2+ The products include C3H7OH, C2H5OH, and HCOOH.

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