Preparation method and application of CuO / MgO nano-catalyst

Abstract

The invention discloses a preparation method and application of a CuO / MgO nano-catalyst, and relates to a preparation method and application of a nano-catalyst. The invention aims to solve the problem that in the existing electrocatalytic CO2 reduction technology, under high current density, an oxide catalyst is easy to generate various reduction products, and high C2H4 selectivity is difficult to achieve. The method comprises the following steps: 1, preparing a precursor solution; 2, hydrothermal reaction; and 3, roasting. According to the application, the CuO / MgO nano-catalyst is used as a raw material for preparing a gas diffusion electrode and is used for electrocatalytic CO2 reduction. The preparation method is used for preparation and application of the CuO / MgO nano-catalyst.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a nano catalyst. Background Art

[0002] The rapid development of modern industry is inseparable from the support of energy, especially the widespread use of electricity. As renewable energy has gradually become an important part of the global energy strategy, electrocatalytic technology has gradually become a research hotspot in the field of energy conversion and storage. In the electrocatalytic process, the selection of catalysts is crucial to improving reaction efficiency and reducing energy consumption. At present, although some pure transition metal catalysts show good catalytic activity in electrocatalytic reactions, there are still challenges such as poor reaction selectivity and low current density in efficient and selective electrocatalytic reactions.

[0003] Oxide composite catalysts have become one of the materials that have attracted widespread attention in the field of electrocatalysis due to their unique structural advantages. The chemical stability and good electronic conductivity of oxides enable them to exhibit remarkable performance in a variety of electrocatalytic reactions. For example, in electrocatalytic reduction reactions (such as CO2 reduction, water electrolysis, etc.), oxide composite catalysts can effectively promote the electron transfer process and optimize the selectivity and efficiency of the catalytic reaction by adjusting their composition and structure.

[0004] The design of oxide composite structures can be optimized by adjusting the crystal structure, surface functional groups, and metal / oxygen coordination environment of the catalyst to improve catalytic performance. The formation of composite structures can not only enhance the stability of the catalyst, but also promote the synergistic effect between different active components, thereby enhancing the activity of the catalytic reaction. For example, combining transition metal oxides with other metal oxides can adjust the electronic structure of the catalyst, improve the electron transfer ability in the electrocatalytic reaction, and thus improve the selectivity and current density of the reaction.

[0005] Although oxide-derived catalysts have shown certain catalytic activity in CO2 reduction reactions, the selectivity of their CO2 reduction products remains to be solved. At high current density, oxide catalysts tend to produce multiple reduction products and it is difficult to achieve high selectivity, especially in the conversion to a single product, C2H4. Summary of the invention

[0006] The present invention aims to solve the problem in the existing electrocatalytic CO2 reduction technology that, under high current density, oxide catalysts easily produce a variety of reduction products and it is difficult to achieve high selectivity for C2H4, and further provide a preparation method and application of a CuO / MgO nanocatalyst.

[0007] A method for preparing a CuO / MgO nanocatalyst is carried out according to the following steps:

[0008] 1. Preparation of precursor solution:

[0009] Under stirring conditions, copper salt is added into water to dissolve to obtain a copper salt solution, and then magnesium salt and a precipitant are added into the copper salt solution and mixed evenly under stirring conditions, and finally, at room temperature, the reaction is stirred for 5 minutes to 80 minutes to obtain a precursor solution;

[0010] 2. Hydrothermal reaction:

[0011] The precursor solution is subjected to a hydrothermal reaction, then cooled to room temperature, and finally separated, washed and dried in sequence to obtain a precursor;

[0012] 3. Roasting:

[0013] The precursor is calcined for 1 h to 4 h in an air or oxygen atmosphere at a temperature of 473 K to 873 K to obtain a CuO / MgO nanocatalyst.

[0014] An application of a CuO / MgO nanocatalyst, wherein the CuO / MgO nanocatalyst is used as a raw material to prepare a gas diffusion electrode for electrocatalytic CO2 reduction.

[0015] The beneficial effects of the present invention are:

[0016] 1. The CuO / MgO alloy catalyst prepared by the present invention exhibits excellent electrocatalytic CO2 reduction performance. When the molar ratio of copper to magnesium is 10:1 and the activation time is 20 min, the CuO / MgO alloy catalyst exhibits excellent electrocatalytic CO2 reduction performance at a working current density of 600 mA cm -2 The selectivity of C2H4 reached 59%.

[0017] 2. The CuO / MgO nanocatalyst prepared by the present invention exhibits excellent electrocatalytic CO2 reduction performance. When the molar ratio of copper to magnesium is 10:1 and the activation time is 20 min, the CuO / MgO nanocatalyst exhibits excellent electrocatalytic CO2 reduction performance at 400-900 mA·cm -2 The C2H4 selectivity is maintained above 50% within the current density range. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 XRD images of the CuO nanocatalyst prepared in the comparative experiment and the CuO / MgO nanocatalyst prepared in Example 1;

[0019] Figure 2 Scanning electron microscope images of the CuO nanocatalyst prepared in the comparative experiment and the CuO / MgO nanocatalyst prepared in Example 1, (a) CuO nanocatalyst, (b) CuO / MgO nanocatalyst;

[0020] Figure 3The selectivity curve of CO2 reduction product of CuO / MgO nanocatalyst prepared in Example 1 varies with applied current density;

[0021] Figure 4 This is the stability test curve of the CO2 reduction process of the CuO / MgO nanocatalyst prepared in Example 1. DETAILED DESCRIPTION

[0022] Specific implementation method 1: This implementation method is a method for preparing a CuO / MgO nanocatalyst, which is carried out according to the following steps:

[0023] 1. Preparation of precursor solution:

[0024] Under stirring conditions, copper salt is added into water to dissolve to obtain a copper salt solution, and then magnesium salt and a precipitant are added into the copper salt solution and mixed evenly under stirring conditions, and finally, at room temperature, the reaction is stirred for 5 minutes to 80 minutes to obtain a precursor solution;

[0025] 2. Hydrothermal reaction:

[0026] The precursor solution is subjected to a hydrothermal reaction, then cooled to room temperature, and finally separated, washed and dried in sequence to obtain a precursor;

[0027] 3. Roasting:

[0028] The precursor is calcined for 1 h to 4 h in an air or oxygen atmosphere at a temperature of 473 K to 873 K to obtain a CuO / MgO nanocatalyst.

[0029] The beneficial effects of this embodiment are:

[0030] 1. The CuO / MgO alloy catalyst prepared in this embodiment exhibits excellent electrocatalytic CO2 reduction performance. When the molar ratio of copper to magnesium is 10:1 and the activation time is 20 min, the CuO / MgO alloy catalyst exhibits excellent electrocatalytic CO2 reduction performance at a working current density of 600 mA cm -2 The selectivity of C2H4 reached 59%.

[0031] 2. The CuO / MgO nanocatalyst prepared in this embodiment exhibits excellent electrocatalytic CO2 reduction performance. When the molar ratio of copper to magnesium is 10:1 and the activation time is 20 min, the CuO / MgO nanocatalyst exhibits excellent electrocatalytic CO2 reduction performance at 400 mA·cm -2 ~900mA·cm -2 The C2H4 selectivity is maintained above 50% within the current density range.

[0032] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the copper salt described in step 1 is copper nitrate, copper chloride, copper sulfate or copper acetate; the magnesium salt described in step 1 is magnesium nitrate, magnesium chloride or magnesium sulfate; the precipitant described in step 1 is urea, sodium carbonate, sodium hydroxide, potassium hydroxide or hexamethylenetetramine. Others are the same as specific implementation method 1.

[0033] Specific implementation method three: This implementation method is different from specific implementation method one or two in that: in step one, under the condition of stirring speed of 200r / min to 1000r / min, copper salt is added to water to dissolve to obtain copper salt solution, and then under the condition of stirring speed of 200r / min to 1000r / min, magnesium salt and precipitant are added to the copper salt solution and mixed evenly, and finally under the condition of room temperature and stirring speed of 200r / min to 1000r / min, stirring reaction is carried out for 5min to 80min to obtain precursor solution. Others are the same as specific implementation method one or two.

[0034] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: the concentration of the copper salt in the copper salt solution described in step 1 is 1mM to 1M; the molar ratio of the copper salt to the magnesium salt described in step 1 is (2 to 10):1; the total molar ratio of the copper salt and magnesium salt described in step 1 to the molar ratio of the precipitant is 1:(1 to 10). Others are the same as specific embodiment 3.

[0035] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the hydrothermal reaction in step 2 is carried out at a temperature of 80° C. to 150° C. for 6 h to 24 h. The rest is the same as specific embodiments 1 to 4.

[0036] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that the separation, washing and drying described in step 2 are specifically carried out according to the following steps: centrifuging for 2 min to 10 min at a rotation speed of 4000 rpm to 9000 rpm to obtain particles, then washing the particles to neutrality using anhydrous ethanol and water as washing liquid, and finally drying the washed particles for 12 h to 24 h at a temperature of 40 ° C to 100 ° C. The rest is the same as specific embodiments 1 to 5.

[0037] Specific implementation method seven: This implementation method is an application of CuO / MgO nanocatalyst. The CuO / MgO nanocatalyst is used as a raw material to prepare a gas diffusion electrode for electrocatalytic CO2 reduction.

[0038] Specific embodiment eight: This embodiment differs from specific embodiment seven in that the gas diffusion electrode is prepared according to the following steps:

[0039] ① Adding CuO / MgO nanocatalyst to a mixed solution of Nafion and isopropanol, and ultrasonically mixing for 10 min to 60 min at a power of 100 W to 500 W to obtain catalyst ink;

[0040] The volume ratio of Nafion solution to isopropanol in the mixed solution of Nafion and isopropanol is 1:(10-31); the concentration of CuO / MgO nanocatalyst in the catalyst ink is 3mg / mL-10mg / mL;

[0041] ② According to the loading amount of CuO / MgO nanocatalyst is 0.5mg / cm 2 ~2.0mg / cm 2 , under the condition of temperature of 35°C to 65°C, the catalyst ink is sprayed onto the carbon paper, and finally dried to obtain a gas diffusion electrode. The rest is the same as the seventh embodiment.

[0042] The operation of preparing the gas diffusion electrode in this embodiment is simple, the CuO / MgO nanocatalyst does not need to be pretreated, and CuO / MgO as an oxide exists stably in an air atmosphere, and there is no need to consider the air oxidation problem.

[0043] Specific embodiment 9: This embodiment is different from specific embodiment 7 or 8 in that: the electrocatalytic CO2 reduction is specifically carried out according to the following steps:

[0044] ① Assembly: Using a flow-type electrolyzer, a gas diffusion electrode is set between the CO2 gas flow chamber and the cathode chamber, and an anion exchange membrane is set between the cathode chamber and the anode chamber; the counter electrode is set in the anode chamber, the reference electrode is set in the cathode chamber, and the cathode liquid flow cell is connected to the cathode chamber through a conduit, and the anode liquid flow cell is connected to the anode chamber through a conduit, and the electrolyte is poured into the cathode liquid flow cell and the anode liquid flow cell, and finally the positive electrode of the power supply is connected to the counter electrode, and the negative electrode of the power supply is connected to the gas diffusion electrode;

[0045] ②Electrocatalytic activation: CO2 gas is introduced into the CO2 gas flow chamber at a flow rate of 1 mL / min to 50 mL / min, and the CO2 is continuously introduced. Under the condition that the potential applied to the gas diffusion electrode is -1.0 V to -3.0 V vsAg / AgCl, the catalyst is activated for 5 min to 60 min.

[0046] ③Electrocatalytic CO2 reduction: CO2 gas is introduced into the CO2 gas flow chamber at a flow rate of 1 mL / min to 50 mL / min. CO2 is continuously introduced at a current density of 50 mA cm at the gas diffusion electrode. -2 ~1A·cm -2Under the conditions of , the electrocatalytic CO2 reduction is carried out, the gas product is collected, and the electrolyte after the reaction is separated and purified, so as to complete the electrocatalytic CO2 reduction. The rest is the same as the specific embodiment seven or eight.

[0047] Specific embodiment 10: This embodiment differs from specific embodiments 7 to 9 in that: the electrolyte described in step ① is a KOH electrolyte with a concentration of 0.5M to 3M; the material of the CO2 gas flow chamber described in step ① is stainless steel; the counter electrode described in step ① is foamed Ni, Pt-plated titanium felt or IrO2-plated titanium felt; the reference electrode described in step ① is an Ag / AgCl electrode. Others are the same as specific embodiments 7 to 9.

[0048] The following examples are used to verify the beneficial effects of the present invention:

[0049] Embodiment 1:

[0050] A method for preparing a CuO / MgO nanocatalyst is carried out according to the following steps:

[0051] 1. Preparation of precursor solution:

[0052] Under the condition of stirring at a speed of 800 r / min, copper salt is added into water to dissolve to obtain a copper salt solution, and then magnesium salt and a precipitant are added into the copper salt solution and mixed evenly under the condition of stirring at a speed of 800 r / min, and finally stirred for reaction at room temperature and a stirring speed of 800 r / min for 5 minutes to obtain a precursor solution;

[0053] 2. Hydrothermal reaction:

[0054] Under the condition of temperature of 100° C., the precursor solution is subjected to hydrothermal reaction for 10 hours, then cooled to room temperature, and finally separated, washed and dried in sequence to obtain a precursor;

[0055] 3. Roasting:

[0056] The precursor was calcined for 1 h in an air atmosphere at 400° C. to obtain a CuO / MgO nanocatalyst.

[0057] The copper salt described in step one is copper chloride; the magnesium salt described in step one is magnesium nitrate; and the precipitant described in step one is sodium hydroxide.

[0058] The concentration of copper salt in the copper salt solution described in step one is 3mM; the molar ratio of the copper salt to the magnesium salt described in step one is 10:1; the ratio of the total molar amount of the copper salt and the magnesium salt described in step one to the molar amount of the precipitant is 1:1.

[0059] The separation, washing and drying described in step 2 are specifically carried out according to the following steps: centrifuge for 2 minutes at a rotation speed of 4000 rpm to obtain particles, then use anhydrous ethanol and water as washing liquid to wash the particles until they are neutral, and finally dry the washed particles at a temperature of 60°C for 12 hours.

[0060] Application of the CuO / MgO nanocatalyst prepared above: the CuO / MgO nanocatalyst is used as a raw material to prepare a gas diffusion electrode for electrocatalytic CO2 reduction;

[0061] The gas diffusion electrode is specifically prepared according to the following steps:

[0062] ① Add the CuO / MgO nanocatalyst to the mixed solution of Nafion and isopropanol, and mix them ultrasonically for 20 minutes at a power of 300 W to obtain catalyst ink;

[0063] The volume ratio of Nafion solution to isopropanol in the mixed solution of Nafion and isopropanol is 1:31; the concentration of CuO / MgO nanocatalyst in the catalyst ink is 7.7 mg / mL;

[0064] ② According to the loading amount of CuO / MgO nanocatalyst is 1.0mg / cm 2 , spraying the catalyst ink onto carbon paper at a temperature of 65°C, and finally drying to obtain a gas diffusion electrode;

[0065] The carbon paper is 28BC;

[0066] The electrocatalytic CO2 reduction is specifically carried out according to the following steps:

[0067] ① Assembly: Using a flow-type electrolyzer, a gas diffusion electrode is set between the CO2 gas flow chamber and the cathode chamber, and an anion exchange membrane is set between the cathode chamber and the anode chamber; the counter electrode is set in the anode chamber, the reference electrode is set in the cathode chamber, and the cathode liquid flow cell is connected to the cathode chamber through a conduit, and the anode liquid flow cell is connected to the anode chamber through a conduit, and the electrolyte is poured into the cathode liquid flow cell and the anode liquid flow cell, and finally the positive electrode of the power supply is connected to the counter electrode, and the negative electrode of the power supply is connected to the gas diffusion electrode;

[0068] The electrolyte is a KOH electrolyte with a concentration of 1M; the material of the CO2 gas flow chamber is stainless steel; the counter electrode is foamed Ni; the reference electrode is an Ag / AgCl electrode; the anion exchange membrane is fumasepFAA-3-PK-130;

[0069] ②Electrocatalytic activation: CO2 gas was introduced into the CO2 gas flow chamber at a flow rate of 30 mL / min, and the CO2 was continuously introduced. The catalyst was activated for 20 min under the condition that the potential applied to the gas diffusion electrode was -2.0 V vs Ag / AgCl;

[0070] ③Electrocatalytic CO2 reduction: CO2 gas was introduced into the CO2 gas flow chamber at a flow rate of 30 mL / min. CO2 was continuously introduced at a current density of 50 mA cm at the gas diffusion electrode. -2 ~900mA·cm -2 The electrocatalytic CO2 reduction is completed by electrocatalytically reducing CO2 under the conditions of , collecting the gas product, separating and purifying the electrolyte after the reaction.

[0071] Example 2: This example is different from Example 1 in that the molar ratio of the copper salt to the magnesium salt in step 1 is 5:1. The rest is the same as Example 1.

[0072] Example 3: This example is different from Example 1 in that the ratio of the total amount of copper salt and magnesium salt to the amount of precipitant in step 1 is 1:3. Others are the same as Example 1.

[0073] Embodiment 4: This embodiment is different from Embodiment 1 in that the air atmosphere is replaced with an oxygen atmosphere in step 3. The rest is the same as Embodiment 1.

[0074] Comparative experiment: The difference between this comparative experiment and Example 1 is that the addition of magnesium salt is eliminated in step 1, and CuO nanocatalyst is obtained in step 3. The rest is the same as Example 1.

[0075] Figure 1 The XRD images of the CuO nanocatalyst prepared in the comparative experiment and the CuO / MgO nanocatalyst prepared in Example 1 are shown in the figure. As can be seen from the figure, the system without adding Mg salt only shows the relevant diffraction peaks of CuO. After adding Mg salt, the system shows the relevant diffraction peaks of MgO in addition to the relevant diffraction peaks of CuO, indicating that CuO / MgO is formed after adding Mg salt.

[0076] Figure 2 Scanning electron microscope images of the CuO nanocatalyst prepared in the comparison experiment and the CuO / MgO nanocatalyst prepared in Example 1, (a) CuO nanocatalyst, (b) CuO / MgO nanocatalyst; it can be seen from the figure that when Cu:Mg=10:1, the CuO changes from a nanosheet morphology to a nanoflower morphology, indicating that MgO helps CuO to self-assemble.

[0077] Figure 3The curve of the selectivity of CO2 reduction products of CuO / MgO nanocatalyst prepared in Example 1 as a function of applied current density. As can be seen from the figure, as the applied current density gradually increases, the main product of electrocatalytic CO2 reduction of CuO / MgO nanocatalyst is C2H4 within most of the applied current density range. Among the gas phase products of CO2 reduction reaction, at a lower current density (200mA·cm -2 ~400mA / cm 2 ) is lower than that at high current density (400 mA cm -2 ~900mA / cm 2 ) of C2H4 selectivity at 400 mA·cm -2 ~900mA·cm -2 The C2H4 selectivity is maintained at more than 50% within the current density range, and at 900mA / cm 2 52% at 600mA / cm 2 The selectivity of CO decreased with the increase of current density, which means that more CO undergoes CC coupling to form C2H4.

[0078] Figure 4 This is the stability test curve of the CO2 reduction process of the CuO / MgO nanocatalyst prepared in Example 1. As can be seen from the figure, at 400mA / cm 2 Under the condition of low temperature and high humidity, the selectivity of C2H4 of CuO / MgO nanocatalyst was maintained at about 50% in the 15-hour stability test, indicating that CuO / MgO nanocatalyst can maintain normal operation for a long time.

Claims

1. A method for preparing a CuO / MgO nanocatalyst, characterized in that It is carried out in the following steps:

1. Preparation of precursor solution: Under stirring conditions, copper salt is added into water to dissolve to obtain a copper salt solution, and then magnesium salt and a precipitant are added into the copper salt solution and mixed evenly under stirring conditions, and finally, at room temperature, the reaction is stirred for 5 minutes to 80 minutes to obtain a precursor solution; 2. Hydrothermal reaction: The precursor solution is subjected to a hydrothermal reaction, then cooled to room temperature, and finally separated, washed and dried in sequence to obtain a precursor; 3. Roasting: The precursor is calcined for 1 h to 4 h in an air or oxygen atmosphere at a temperature of 473 K to 873 K to obtain a CuO / MgO nanocatalyst.

2. The method for preparing a CuO / MgO nanocatalyst according to claim 1, characterized in that The copper salt described in step one is copper nitrate, copper chloride, copper sulfate or copper acetate; the magnesium salt described in step one is magnesium nitrate, magnesium chloride or magnesium sulfate; the precipitant described in step one is urea, sodium carbonate, sodium hydroxide, potassium hydroxide or hexamethylenetetramine.

3. The method for preparing a CuO / MgO nanocatalyst according to claim 1, characterized in that In step 1, copper salt is added into water to dissolve under the condition of stirring speed of 200 r / min to 1000 r / min to obtain copper salt solution, and then magnesium salt and precipitant are added into the copper salt solution and mixed evenly under the condition of stirring speed of 200 r / min to 1000 r / min, and finally, the reaction is stirred for 5 min to 80 min at room temperature and stirring speed of 200 r / min to 1000 r / min to obtain a precursor solution.

4. The method for preparing a CuO / MgO nanocatalyst according to claim 1, characterized in that The concentration of copper salt in the copper salt solution described in step one is 1mM to 1M; the molar ratio of the copper salt to the magnesium salt described in step one is (2 to 10):1; the molar ratio of the total molar amount of the copper salt and the magnesium salt described in step one to the molar amount of the precipitant is 1:(1 to 10).

5. The method for preparing a CuO / MgO nanocatalyst according to claim 1, characterized in that The hydrothermal reaction in step 2 is specifically carried out at a temperature of 80° C. to 150° C. for 6 h to 24 h.

6. The method for preparing a CuO / MgO nanocatalyst according to claim 1, characterized in that The separation, washing and drying described in step 2 are specifically carried out according to the following steps: centrifuge for 2min to 10min at a rotation speed of 4000rpm to 9000rpm to obtain particles, then use anhydrous ethanol and water as washing liquid to wash the particles until they are neutral, and finally dry the washed particles at a temperature of 40℃ to 100℃ for 12h to 24h.

7. The use of a CuO / MgO nanocatalyst prepared as claimed in claim 1, characterized in that CuO / MgO nanocatalysts were used as raw materials to prepare gas diffusion electrodes for electrocatalytic CO2 reduction.

8. The use of a CuO / MgO nanocatalyst according to claim 7, characterized in that The gas diffusion electrode is specifically prepared according to the following steps: ① Adding CuO / MgO nanocatalyst to a mixed solution of Nafion and isopropanol, and ultrasonically mixing for 10 min to 60 min at a power of 100 W to 500 W to obtain catalyst ink; The volume ratio of Nafion solution to isopropanol in the mixed solution of Nafion and isopropanol is 1:(10-31); the concentration of CuO / MgO nanocatalyst in the catalyst ink is 3mg / mL-10mg / mL; ② According to the loading amount of CuO / MgO nanocatalyst is 0.5mg / cm 2 ~2.0mg / cm 2 , the catalyst ink is sprayed onto carbon paper at a temperature of 35°C to 65°C, and finally dried to obtain a gas diffusion electrode.

9. The use of a CuO / MgO nanocatalyst according to claim 7, characterized in that The electrocatalytic CO2 reduction is specifically carried out according to the following steps: ① Assembly: Using a flow-type electrolyzer, a gas diffusion electrode is set between the CO2 gas flow chamber and the cathode chamber, and an anion exchange membrane is set between the cathode chamber and the anode chamber; the counter electrode is set in the anode chamber, the reference electrode is set in the cathode chamber, and the cathode liquid flow cell is connected to the cathode chamber through a conduit, and the anode liquid flow cell is connected to the anode chamber through a conduit, and the electrolyte is poured into the cathode liquid flow cell and the anode liquid flow cell, and finally the positive electrode of the power supply is connected to the counter electrode, and the negative electrode of the power supply is connected to the gas diffusion electrode; ②Electrocatalytic activation: CO2 gas is introduced into the CO2 gas flow chamber at a flow rate of 1 mL / min to 50 mL / min, and CO2 is continuously introduced. Under the condition that the potential applied to the gas diffusion electrode is -1.0 V to -3.0 V vs Ag / AgCl, the catalyst is activated for 5 min to 60 min. ③Electrocatalytic CO2 reduction: CO2 gas is introduced into the CO2 gas flow chamber at a flow rate of 1 mL / min to 50 mL / min. CO2 is continuously introduced at a current density of 50 mA cm at the gas diffusion electrode. -2 ~1A·cm -2 The electrocatalytic CO2 reduction is completed by electrocatalytically reducing CO2 under the conditions of , collecting the gas product, separating and purifying the electrolyte after the reaction.

10. The use of a CuO / MgO nanocatalyst according to claim 9, characterized in that The electrolyte described in step ① is a KOH electrolyte with a concentration of 0.5M to 3M; the material of the CO2 gas flow chamber described in step ① is stainless steel; the counter electrode described in step ① is foamed Ni, Pt-plated titanium felt or IrO2-plated titanium felt; the reference electrode described in step ① is an Ag / AgCl electrode.

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