Method for electrocatalytic reduction of carbon dioxide by copper-based hollow silver composite nanocatalyst

Abstract

The application belongs to the technical field of electrocatalysis application, and relates to a composite catalytic electrode, in particular to a method for electrocatalytically reducing carbon dioxide by using a copper-based hollow silver composite nanocatalyst, which comprises the following steps: using carbon paper loaded with Cu-Ag composite nanoparticles as a working electrode, using a platinum sheet as a counter electrode, adding prepared CO2-saturated electrolyte solution to both sides of an H-shaped electrolytic cell, continuously introducing CO2 to remove oxygen, and then performing electrocatalytic reduction of carbon dioxide at a gas flow rate of 20-100 mL / min and a temperature of 20-30 DEG C. The Cu-Ag electrocathode material is synthesized through simple constant-temperature stirring deposition, the prepared copper-based hollow silver composite nanocatalyst enhances the electrochemical active area of the catalyst, exhibits stronger catalytic activity, and accelerates the formation of CO2RR intermediates, and the catalyst has good application prospect in the fields of environment and energy.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis application technology, and relates to composite catalytic electrodes, and more particularly to a method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst. Background Technology

[0002] Generally, metal nanoparticles possess a high surface-to-volume ratio, which plays a crucial role in their excellent physical, chemical, and biological properties. Hybrid nanostructures composed of metal oxide semiconductor-noble metal nanocomposites are an interesting class of nanomaterials. Compared with single-component semiconductor metal oxides and noble metal nanoparticles, they can retain the characteristics of each component and exhibit superior performance. Lan et al. successfully prepared Cu₂O / Ag 0 Ag nanocatalysts degrade dyes, exhibiting high catalytic activity under both dark and light conditions due to the synergistic effect of Cu and Ag. Rao et al. synthesized a heterostructure of Ag / Cu₂O hybrids for photocatalytic degradation; the enhancement of UV-Vis absorption spectroscopy and electron deposition effect by Ag nanoparticle deposition were key factors in improving the photocatalytic activity of the Ag / Cu₂O heterostructure. Wu et al. prepared Ag:Cu₂O films on single-crystal MgO substrates using pulse deposition, successfully improving their photoelectrochemical performance.

[0003] In recent decades, the overuse of fossil fuels has led to a significant increase in carbon dioxide, accelerating global warming and triggering various environmental problems. To reduce carbon dioxide emissions, an ideal strategy is to utilize carbon dioxide as a feedstock, converting it into valuable chemicals and fuels. Electrochemical CO2 reduction reaction (CO2RR) is an attractive method for utilizing CO2 due to its advantages, such as pollution-free production and controllable product formation. However, carbon dioxide is completely oxidized and thermodynamically stable, indicating the need for substantial energy. Therefore, the rational design and synthesis of CO2RR catalysts with high selectivity (Faraday efficiency, FE), low overpotential, and high stability has become a focus of attention. Among various electrocatalysts, metals exhibit excellent catalytic activity for CO2RR, with Au and Ag reported as ideal catalysts for CO2RR to CO. However, Au's high cost and low abundance limit its industrial application potential. Compared to Au, Ag offers lower cost and good selectivity, showing great potential for large-scale application. However, the high overpotential driving selective CO2RR and rapid catalytic deactivation to promote H2 generation on Ag catalysts severely limit its practical application. Summary of the Invention

[0004] The purpose of this invention is to provide a method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst.

[0005] Technical solution:

[0006] Using copper sulfate, oleic acid, sodium hydroxide, and sodium ascorbate as raw materials, concave octahedral Cu2O was first prepared by constant temperature stirring. Then, using silver nitrate, nitric acid, trisodium citrate, and conductive carbon paper as raw materials, CAx was prepared by stirring and precipitation.

[0007] A method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CAx, x = 0, 0.5, 1.5, 2.5, 3.5) includes: using carbon paper loaded with Cu-Ag composite nanoparticles as the working electrode, a platinum sheet as the counter electrode, adding a prepared CO2-saturated electrolyte solution to both sides of an H-type electrolytic cell, continuously introducing CO2 to remove oxygen, and then performing electrocatalytic carbon dioxide reduction at a gas flow rate of 20–100 mL / min and a temperature of 20–30 °C.

[0008] In a preferred embodiment of the present invention, the carbon paper supported on Cu-Ag composite nanoparticle catalyst is prepared by means of: preparing a solution by mixing concave octahedral Cu2O, trisodium citrate and water in a molar / volume ratio of 1-2 mmol:1 mmol:25 mL and stirring; adding silver nitrate, wherein the molar ratio of Ag to Cu is 0, 0.5, 1.5, 2.5, or 3.5, abbreviated as CA0, CA0.5, CA1.5, CA2.5, or CA3.5; stirring vigorously for 10-15 min; adding 5 mL of 0.1-0.3 mM dilute nitric acid; centrifuging and washing after the reaction is complete; drying under vacuum at 50 °C; and finally, using conductive carbon paper as a support substrate, ultrasonically uniformly coating the catalyst particles onto the substrate surface and drying to obtain the final product.

[0009] In a preferred embodiment of the present invention, the CO2-saturated electrolyte solution is prepared with a concentration of 0.1–0.5 mol·L⁻¹. -1 0.1 mol·L -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

[0010] In a preferred embodiment of the present invention, the operating voltage of the electrolytic cell is -1.3 to -0.9V.

[0011] The preparation method of the concave octahedral Cu2O described in this invention is detailed in CN107720803A.

[0012] This invention utilizes a simple stirring method to prepare uniform, hollow, porous silver nanoparticles. Subsequently, porous silver nanoparticles (synthesized using concave octahedral Cu₂O crystals as templates) were prepared using carbon paper as a substrate and served as the working electrode for the electrocatalytic reduction of carbon dioxide. The Ag catalyst exhibits excellent activity for CO₂RR, achieving an electrochemical activity (FE) of 91.7% for CO at -1.1V, significantly higher than the catalytic activity of solid Ag reported in relevant literature. The catalyst also demonstrates significant catalytic stability for CO₂RR. The electrochemical active area of ​​this catalyst is much larger than that of concave octahedral Cu₂O and superior to that of solid Ag particles, thus exhibiting stronger catalytic activity and promoting CO formation. Therefore, this discovery may provide new insights for the design and synthesis of CO₂RR electrocatalysts.

[0013] The advantages of this invention are: the preparation method is easily controllable, the reaction time is short, and the target product is easily obtained. The hollow structure of the nanocatalyst effectively increases its electrochemical active area, thereby increasing the number of active sites. The resulting carbon dioxide reduction electrocatalyst has good activity in the electrocatalytic reduction of CO2 to carbon monoxide.

[0014] The morphology, structure and composition of the CAx composite nanoparticle catalyst prepared in this invention were analyzed using instruments such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The photocurrent density curve (JV) was measured using a standard three-electrode electrochemical workstation to evaluate its electrocatalytic carbon dioxide reduction performance.

[0015] All reactants and reagents used in this invention are commercially available.

[0016] Beneficial effects

[0017] This invention synthesizes Cu-Ag cathode materials through a simple isothermal stirring deposition process. The prepared copper-based hollow silver composite nanocatalyst enhances the electrochemical active area of ​​the catalyst, exhibits stronger catalytic activity, and accelerates the formation of CO2RR intermediates. This catalyst has good application prospects in environmental, energy and other fields. Attached Figure Description

[0018] Figure 1 XRD pattern of the CA1.5 nanoparticle catalyst prepared in Example 3;

[0019] Figure 2 XPS spectrum of the CA1.5 nanoparticle catalyst prepared in Example 3;

[0020] Figure 3 SEM image of the CA1.5 nanoparticle catalyst prepared in Example 3;

[0021] Figure 4The CAx nanoparticle catalysts prepared in Examples 1-5 have C dl picture;

[0022] Figure 5 The Faraday efficiency diagram of the CA1.5 nanoparticle catalyst prepared in Example 3 at various potentials;

[0023] Figure 6 Faraday efficiency diagrams of the CAx nanoparticle catalysts prepared in Examples 1-5 at various potentials for carbon monoxide. Detailed Implementation

[0024] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0025] Example 1

[0026] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA0) in electrocatalytic carbon dioxide reduction includes the following steps:

[0027] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0028] B. Using carbon paper loaded with CA0 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0029] The CA0 nanoparticle catalyst uses carbon paper as a substrate, and the catalyst particles are drop-coated onto its surface after being ultrasonically homogenized.

[0030] The CA0 nanocatalyst exhibits a Faraday efficiency of 7% within the range of -0.9V to -1.3V, with an optimal voltage of -1V.

[0031] Example 2

[0032] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA0.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0033] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0034] B. Using carbon paper loaded with CA0.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0035] The carbon paper supported on the CA0.5 composite nanoparticle catalyst is prepared by: stirring 25 mL of a mixed solution of 10 mg of concave octahedral Cu₂O and 0.088 g of trisodium citrate until homogeneous; adding 0.0255 g of silver nitrate (Ag to Cu molar ratio of 0.5, abbreviated as CA0.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, using carbon paper as the supporting substrate, the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0036] The CA0.5 nanocatalyst exhibits a Faraday efficiency of 47% within the range of -0.9V to -1.3V, with an optimal voltage of -0.9V.

[0037] Example 3

[0038] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA1.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0039] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0040] B. Using carbon paper loaded with CA1.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0041] The carbon paper supported on the CA1.5 composite nanoparticle catalyst is prepared by: stirring 25 mL of a mixed solution of 10 mg of concave octahedral Cu₂O and 0.088 g of trisodium citrate until homogeneous; adding 0.0765 g of silver nitrate (Ag to Cu molar ratio of 1.5, abbreviated as CA1.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, using carbon paper as the supporting substrate, the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0042] The CA1.5 nanocatalyst exhibits a Faraday efficiency of 91.7% within the range of -0.9V to -1.3V, with an optimal voltage of -1.1V.

[0043] Depend on Figure 1 The XRD results showed that most of the Cu2O in the CAx catalyst had been washed away. Figure 2 XPS results also confirmed the presence of Ag and trace amounts of Cu in the catalyst. 1+ The existence of.

[0044] from Figure 3 The results of medium-wave scanning electron microscopy can reveal the porous morphology of the catalyst; such as Figure 4 As shown, by comparing the electrochemical active areas of each catalyst, it is easy to find that, compared with pure metallic silver, the electrochemical active areas of all hollow porous structure catalysts have been effectively improved.

[0045] Figure 5 The results show that CA1.5 has a very strong selectivity for CO.

[0046] Example 4

[0047] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA2.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0048] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0049] B. Using carbon paper loaded with CA2.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0050] The carbon paper supported on the CA2.5 composite nanoparticle catalyst is prepared by: stirring a 25 mL mixture of 10 mg of concave octahedral Cu2O and 0.088 g of trisodium citrate until homogeneous; adding 0.1275 g of silver nitrate (Ag to Cu molar ratio of 2.5, abbreviated as CA2.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. The catalyst particles are then drop-coated onto the surface of the carbon paper as a supporting substrate after ultrasonic homogenization.

[0051] The CA2.5 nanocatalyst exhibits a Faraday efficiency of 82.8% within the range of -0.9V to -1.3V, with an optimal voltage of -1.1V.

[0052] Example 5

[0053] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA3.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0054] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KHCO3 solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0055] B. Using carbon paper loaded with CA3.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0056] The carbon paper supported on the CA3.5 composite nanoparticle catalyst is prepared by: stirring 25 mL of a mixed solution of 10 mg of concave octahedral Cu2O and 0.088 g of trisodium citrate until homogeneous; adding 0.1785 g of silver nitrate (Ag to Cu molar ratio of 3.5, abbreviated as CA3.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, using carbon paper as the supporting substrate, the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0057] The CA3.5 nanocatalyst exhibits a Faraday efficiency of 82.6% within the range of -0.9V to -1.3V, with an optimal voltage of -1.1V.

[0058] To compare the effect of Ag doping amount on the catalytic reduction of carbon dioxide, the performance results of various catalysts were compared, such as... Figure 6 As shown, the selectivity for CO reaches its highest level when the molar ratio of Ag to Cu is 1.5.

[0059] Example 6

[0060] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA1.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0061] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The KOH solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0062] B. Using carbon paper loaded with CA1.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0063] The carbon paper supported on the CA1.5 composite nanoparticle catalyst is prepared by: stirring 25 mL of a mixed solution of 10 mg of concave octahedral Cu₂O and 0.088 g of trisodium citrate until homogeneous; adding 0.0765 g of silver nitrate (Ag to Cu molar ratio of 1.5, abbreviated as CA1.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, using carbon paper as the supporting substrate, the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0064] The CA1.5 nanocatalyst exhibits a Faraday efficiency of 80.5% within the range of -0.9V to -1.3V, with an optimal voltage of -1.1V.

[0065] Example 7

[0066] The application of a copper-based hollow silver composite nanocatalyst (Cu-Ag, abbreviated as CA1.5) in electrocatalytic carbon dioxide reduction includes the following steps:

[0067] A. Prepare 60 mL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The NaCl solution was placed in the dark and CO2 was continuously bubbled through it for 30 minutes until the solution was saturated.

[0068] B. Using carbon paper loaded with CA1.5 composite nanoparticles as the working electrode and a platinum sheet as the counter electrode, a CO2-saturated KHCO3 solution was added to both sides of the H-type electrolytic cell, and CO2 was continuously introduced to remove oxygen. Then, electrocatalytic carbon dioxide reduction was carried out at 25°C with a flow rate of 50 mL / min.

[0069] The carbon paper supported on the CA1.5 composite nanoparticle catalyst is prepared by: stirring 25 mL of a mixed solution of 10 mg of concave octahedral Cu₂O and 0.088 g of trisodium citrate until homogeneous; adding 0.0765 g of silver nitrate (Ag to Cu molar ratio of 1.5, abbreviated as CA1.5); stirring vigorously for 10–15 min; and then adding 5 mL of 0.3 mM dilute nitric acid to the solution. After 20 min, the resulting solution is centrifuged, washed, and dried under vacuum at 50 °C. Subsequently, using carbon paper as the supporting substrate, the catalyst particles are drop-coated onto its surface after ultrasonic homogenization.

[0070] The CA1.5 nanocatalyst exhibits a Faraday efficiency of 77.5% within the range of -0.9V to -1.3V, with an optimal voltage of -1.1V.

[0071] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst, characterized in that: Using carbon paper loaded with copper-based hollow silver composite nanocatalyst as the working electrode and platinum sheet as the counter electrode, a prepared electrolyte solution saturated with CO2 was added to both sides of the H-type electrolytic cell. CO2 was continuously introduced to remove oxygen, and then electrocatalytic carbon dioxide reduction was carried out at a gas flow rate of 20-100 mL / min at 20-30℃. The carbon paper supported on the copper-based hollow silver composite nanocatalyst is prepared by the following method: a solution is prepared by mixing concave octahedral Cu₂O, trisodium citrate, and water in a molar / volume ratio of 1–2 mmol:1 mmol:25 mL and stirring. Silver nitrate is added, with Ag to Cu molar ratios of 0.5, 1.5, 2.5, and 3.5, abbreviated as CA0.5, CA1.5, CA2.5, and CA3.

5. After vigorous stirring for 10–15 min, 5 mL of 0.1–0.3 mM dilute nitric acid is added. After the reaction is complete, the mixture is centrifuged, washed, and dried under vacuum at 50 °C. Finally, using conductive carbon paper as a support substrate, the catalyst particles are ultrasonically homogenized and drop-coated onto the substrate surface. After drying, the catalyst is obtained.

2. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 1, characterized in that: The CO2-saturated electrolyte solution is prepared with a concentration of 0.1–0.5 mol·L⁻¹. -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

3. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 2, characterized in that: The CO2-saturated electrolyte solution is prepared with a concentration of 0.1 mol·L⁻¹. -1 Place the KHCO3, KOH, or NaCl solution in the dark and saturate it with CO2.

4. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 1, characterized in that: The working voltage of the electrolytic cell is -1.3 to -0.9 V.

5. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 1, characterized in that, The concave octahedral Cu₂O is prepared by the following steps: Step 1: Dissolve the copper salt aqueous solution in a mixed solution of water and oleic acid; Step 2: Add an alkaline solution to the solution obtained in Step 1, stir well, and heat to maintain the temperature; Step 3: Add a reducing agent to the solution obtained in Step 2 and continue stirring until the reaction yields crude cuprous oxide product; Step 4: Wash the crude cuprous oxide product obtained in Step 3 and vacuum dry it to obtain the final product.

6. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step one, the copper salt aqueous solution is a divalent copper salt aqueous solution, including one or a combination of two of copper sulfate aqueous solution or copper acetate aqueous solution.

7. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step one, the concentration of the copper salt aqueous solution is 0.01–0.1 mol / L, and the volume is 1 mL.

8. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step one, the volume ratio of water to oleic acid is 20:

1.

9. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: The alkaline solution in step two includes one or a combination of sodium hydroxide aqueous solution or potassium hydroxide aqueous solution.

10. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step two, the concentration of the alkaline aqueous solution is 0.1–1 mol / L, and the volume is 1 mL.

11. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step two, the heating and heat preservation temperature is 50-60℃.

12. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step three, the reducing agent includes one or a combination of two of ascorbic acid or sodium ascorbate.

13. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step three, the concentration of the reducing agent is 0.01–0.1 mol / L, and the volume is 1 mL.

14. The method for electrocatalyzing carbon dioxide using a copper-based hollow silver composite nanocatalyst according to claim 5, characterized in that: In step four, the crude cuprous oxide product is washed with a mixed solvent of ethanol and cyclohexane, and the washing is repeated 2 to 3 times.

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