A method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential

Abstract

This invention discloses a method for pulse-potential controlled electrocatalytic reduction of carbon dioxide by basic copper nitrate, using basic copper nitrate as a catalyst and employing pulse-potential control for the carbon dioxide electrocatalytic reduction reaction. By alternately applying different potentials to the working electrode and controlling the pulse duration, the valence state of the basic copper nitrate catalyst surface and the coverage of reaction intermediates can be dynamically controlled. By optimizing the pulse parameters, a Faradaic efficiency of 52.5% for C2H4 can be achieved at low oxidation potentials, while CH4 and H2 byproducts are significantly suppressed; at high oxidation potentials, a Faradaic efficiency of 43.05% for CH4 can be achieved, while ethylene formation is suppressed, realizing efficient switching between methane and ethylene products. This invention is simple to operate, provides significant product selectivity control, and has high current density, demonstrating high potential for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical carbon dioxide reduction technology, specifically relating to a method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential, which can precisely control the reaction pathway and improve the selectivity of methane or ethylene. Background Technology

[0002] With the continued growth of global energy demand, over-reliance on fossil fuels has led to the risk of energy shortages and a sustained increase in carbon emissions. Electrochemical carbon dioxide reduction reaction (CO2RR) is an effective method to convert greenhouse gases into high-value-added fuels and chemicals, providing a promising pathway for reducing carbon emissions. The CO2RR catalytic reaction pathway is complex and can generate a variety of carbon-based products; therefore, precisely controlling the reaction pathway and product selectivity is a core challenge in this field.

[0003] Among various electrocatalysts, copper-based catalysts are the only ones that facilitate the production of energy-intensive C1 and C2 catalysts. 2+ Copper-based catalysts are suitable for reacting hydrocarbons and oxides (such as ethylene and ethanol) and exhibit significant Faradaic efficiency. However, their complex reaction pathways lead to a wide product distribution, resulting in competition among different CO2RR intermediates and low selectivity for the target product. Furthermore, under strong base and high current density conditions, copper-based catalysts are prone to metallization, surface reconstruction, and loss of active sites, leading to structural instability and posing a challenge to achieving high selectivity for a single CH4 or C2H4 product.

[0004] Basic copper nitrate (Cu4(NO3)2(OH)6), as a typical basic copper salt, possesses the catalytic activity of copper-based compounds and is a promising catalyst material with broad application prospects. However, under traditional potentiostatic mode, this catalyst exhibits instability at its active sites, similar to other copper-based compounds, making it difficult to achieve ideal selectivity when used for electrocatalytic CO2 reduction. Therefore, we introduced pulsed electrocatalysis technology to effectively regulate and optimize the directed synthesis of CO2 electroreduction products. The basic copper nitrate catalyst undergoes dynamic evolution under pulsed electrochemical conditions. By periodically applying pulsed voltage, the surface state, reaction pathway, and product selectivity of the copper-based catalyst can be effectively controlled, alleviating electrode passivation, optimizing the adsorption behavior of key intermediates, and suppressing side reactions, thereby improving the efficiency and stability of CO2 reduction and gradually demonstrating the potential for fine-tuning the CO2RR pathway. For example, in the patent document with publication number CN 114635161 A, a strategy of alternately applying different potentials to the working electrode at a certain frequency is proposed to change the CO2 concentration near the working electrode and the coverage of the reaction intermediate product *CO, thereby adjusting the selectivity of the reaction products. However, the Faraday efficiency of the CH4 and C2H4 produced by its electrolytic reduction products is low, making it difficult to achieve precise control of the selectivity of carbon dioxide reduction products.

[0005] For example, patent document CN 120649053 A describes the in-situ growth of a three-dimensional porous Cu2O / ZnCu2O / Zn bimetallic heterojunction thin-film electrode on a copper mesh substrate for pulsed carbon dioxide electroreduction reactions. The catalyst highly directs the reaction pathway towards the CO products. Although CO is an important chemical feedstock (such as syngas), its added value is relatively low. In contrast, reducing CO2 to CH4 and C2H4 has higher commercial value and energy density. This technical route does not involve CC coupling reactions, thus limiting its application scenarios.

[0006] It is evident that current methods in the field of carbon dioxide electrocatalytic reduction primarily focus on modifying catalysts to optimize product selectivity. However, these methods suffer from limited product switching capabilities and low Faraday efficiency. Furthermore, achieving selective conversion of different products often necessitates the repeated preparation and optimization of multiple catalysts, resulting in complex experimental procedures and lengthy cycles. Simultaneously, the morphology, composition, and active sites of the catalysts are difficult to precisely control during preparation, leading to poor batch-to-batch reproducibility and further limiting the potential for large-scale application of this technology. Summary of the Invention

[0007] To address the problem of uncontrollable product selectivity in existing carbon dioxide electroreduction technologies, this invention provides a synergistic regulation method based on pulse potential. By precisely designing pulse parameters and catalyst systems, the crystal facets and oxidation states of the catalyst are controlled, enabling on-demand synthesis of methane and ethylene products.

[0008] To achieve the directed electrosynthesis of specific hydrocarbons (C2 or C1), this paper uses three-dimensional porous Cu4(NO3)2(OH)6 as a catalyst and constructs multivalent copper active site pairs through a pulse electrolysis strategy, realizing the controllable switching of C2H4 and CH4 in the CO2RR process.

[0009] Specifically, the pulse electrolysis strategy employed in this invention achieves dynamic control of the valence state of active sites and the coverage of intermediates through periodic potential switching, at C1 and C2. 2+ Flexible and effective adjustment was achieved between the reaction pathways. By comparing the experimental parameters and catalyst remodeling behavior under different pulse electrolysis conditions, it can be seen that the oxidation potential (anodic potential, E...)... a The oxidation potential (EPP) is the core variable controlling the in-situ reconstruction pathway, valence state composition, and product selectivity of basic copper nitrate. At low oxidation potentials, the catalyst is reconstructed into a low-valence Cu / Cu₂O mixed state. This interface significantly enhances *CO adsorption and C–C coupling, resulting in a maximum C₂H₄ selectivity of 52.5%. At high oxidation potentials, the catalyst is reconstructed into a high-valence Cu₂O / CuO mixed state. This interface promotes deep hydrogenation of *CHO, achieving a maximum CH₄ selectivity of 43.05%. These results demonstrate that adjusting the pulse parameters can directly alter the distribution and evolution of multivalent copper sites on the surface of the basic copper nitrate catalyst under pulsed electrolysis conditions, thereby enabling controllable switching of CO₂ electrocatalytic reduction products between ethylene and methane.

[0010] A method for pulse potential modulation of the selectivity of electrocatalytic carbon dioxide reduction products includes:

[0011] A flow electrolytic cell was used, with nickel foam as the counter electrode, Ag / AgCl as the reference electrode, carbon paper with a basic copper nitrate catalyst sprayed on its surface as the working electrode, and potassium hydroxide solution as the electrolyte.

[0012] The electrocatalytic reduction of carbon dioxide was carried out using pulse potential, and the selectivity of methane and ethylene in the reduction products was controlled by adjusting the pulse potential and pulse time.

[0013] Preferably, the anode potential is set to 0.4~0.8 V to increase ethylene formation while suppressing methane formation. More preferably, it is 0.6 V.

[0014] Preferably, the anode potential is set to 1~1.4 V to increase methane formation while suppressing ethylene formation. More preferably, it is 1.2 V.

[0015] Preferably, the duration of a single pulse is 5-35 s, and the alternation period is 10-70 s. More preferably, the duration of a single pulse is 10-30 s, and the alternation period is 20-60 s. Even more preferably, the duration of a single pulse is 10-20 s, and the alternation period is 20-40 s.

[0016] Preferably, the ratio of the duration of the cathode potential to that of the anode potential is 1:1.

[0017] Preferably, the preparation method of the basic copper nitrate catalyst is as follows:

[0018] (1) Dissolve copper nitrate trihydrate in diethylene glycol diethyl ether to obtain solution A;

[0019] (2) Dissolve sodium bicarbonate in a mixed solvent consisting of diethylene glycol and deionized water to obtain solution B;

[0020] (3) Heat solution A and slowly add solution B under stirring to keep the temperature for reaction, then raise the temperature and continue the reaction. After the reaction is completed, the basic copper nitrate catalyst is obtained by post-treatment.

[0021] As a further preferred option, the mass-to-volume ratio of copper nitrate trihydrate to diethylene glycol diethyl ether is 8-12 mg / mL.

[0022] As a further preferred option, the mass-to-volume ratio of sodium bicarbonate to the mixed solvent is 7~10 mg / mL.

[0023] As a further preferred option, the volume ratio of diethylene glycol to deionized water in the mixed solvent is (4~6):1.

[0024] As a further preferred option, the mass ratio of copper nitrate trihydrate to sodium bicarbonate is (2~4):1.

[0025] As a further preferred option, in step (3), the temperature of the heat preservation reaction is 80~120 ℃ and the reaction time is 10~30 min.

[0026] As a further preferred option, the reaction temperature after heating is 100~200 °C, and the reaction time is 20~40 min. Even more preferred is a reaction temperature of 150 °C and a reaction time of 30 min.

[0027] Preferably, the stirring speed is 800~1200 rpm.

[0028] As a further preferred option, the post-processing in step (3) is as follows:

[0029] After the reaction was completed and cooled, the solid precipitate in the system was collected by centrifugation and washed three times with anhydrous ethanol. Then, it was dried under vacuum to obtain the basic copper nitrate catalyst.

[0030] As a further preferred option, the vacuum drying temperature is 50~70 °C and the time is 4~8 h. Even more preferably, the vacuum drying temperature is 60 °C and the time is 6 h.

[0031] Preferably, the working electrode is prepared by the following method:

[0032] Basic copper nitrate is placed in a mixed solution of isopropanol and Nafion solution, and ultrasonically treated to form a uniform catalyst ink. The catalyst ink is then uniformly sprayed onto carbon paper with a gas diffusion layer using a spray gun, and dried at room temperature to obtain the working electrode.

[0033] As a further preferred embodiment, in the mixed solution of isopropanol and Nafion solution, the volume ratio of isopropanol to Nafion solution is (5~6):1.

[0034] As a further preferred option, the mass-to-volume ratio of the mixed solution of basic copper nitrate, isopropanol, and Nafion solution is 15-20 g / L.

[0035] As a further preferred option, the ultrasonic treatment time is 20-40 minutes.

[0036] Preferably, the concentration of the potassium hydroxide solution is 0.5~1.5 mol / L. More preferably, it is 1 mol / L.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The method for controlling product selectivity by pulse potential proposed in this invention has the advantages of improving the selectivity of CH4 or C2H4 products and being easy to operate: by alternately applying the cathode and anode potentials to the working electrode, the oxidation state of the basic copper nitrate catalyst is controlled, and the pulse duration is controlled so that the Faraday efficiency of C2H4 is as high as 52.5%. 2+ The Faraday efficiency is as high as 83.6%; or the Faraday efficiency of CH4 is in the range of E. c It reaches 43.05% at -1.6 V.

[0039] (2) In the electrocatalytic CO2 reduction reaction, the pulsed electrolysis strategy of this invention exhibits excellent CH4 or C2H4 selectivity. Under pulsed conditions E a =0.6 V, t a =t c At 20 s, the catalyst at E cAt -1.4 V, it exhibits excellent C2H4 selectivity with a Faraday efficiency of up to 52.5%, and no CH4 product was detected. When the pulse condition is E... a =1.2 V, t a =t c At 10 s, the product distribution changed significantly. Throughout the test range, the Faraday efficiency of C2H4 decreased to below 15%, while the Faraday efficiency of CH4 was lower at E0. c It reaches 43.05% at -1.6 V.

[0040] (3) The method of this invention only requires adjusting the electrochemical pulse program parameters on the same catalyst system to control the reaction path and achieve controllable switching of CO2 electroreduction products between ethylene and methane. It eliminates the need for repeated synthesis of multiple catalysts, simplifying experimental steps and reducing material and time costs. Furthermore, its key operating parameters support quantifiable autonomous control with a reasonable controllable range and precision. This invention is simple to operate, exhibits significant product selectivity control, and boasts high current density, making it highly promising for industrial application.

[0041] The pulse electrolysis strategy proposed in this invention breaks through the limitations of traditional catalyst modification, and can achieve efficient switching between methane and ethylene selectivity while ensuring high conversion efficiency, providing a new solution for product-oriented control. Attached Figure Description

[0042] Figure 1 In Example 1, the pulse condition is E a =0.6 V, t a =t c Faraday efficiency of each reduction product at 20 s;

[0043] Figure 2 In Example 2, the pulse condition is E a =1.2 V, t a =t c Faraday efficiency of each reduction product at 10 s;

[0044] Figure 3 In Example 3, the pulse condition is E a =0.6 V, t a =t c Faraday efficiency of each reduction product at 10 s;

[0045] Figure 4 In Example 4, the pulse condition is E. a =0.6 V, t a =t c Faraday efficiency of each reduction product at 30 s;

[0046] Figure 5 In Example 5, the pulse condition is E a =1.2 V, t a =t c Faraday efficiency of each reduction product at 20 s;

[0047] Figure 6 In Example 6, the pulse condition is E a =1.2 V, t a =t c Faraday efficiency of each reduction product at 30 s;

[0048] Figure 7 The Faraday efficiency of each reduction product of the basic copper nitrate catalyst under constant pressure is shown in Comparative Example 1. Detailed Implementation

[0049] The present invention will be further described in detail below through specific embodiments.

[0050] Example 1

[0051] (1) Weigh 300 mg of copper nitrate trihydrate solid, add it to 30 mL of diethylene glycol diethyl ether solvent, stir thoroughly until completely dissolved, and prepare precursor solution A for later use. Weigh 100 mg of sodium bicarbonate, dissolve it in a pre-prepared mixed solvent (10 mL of diethylene glycol + 2 mL of deionized water), stir until dissolved evenly, and prepare alkaline precursor solution B.

[0052] (2) Place the prepared solution A in a heating and stirring apparatus, heat it to 100 ℃ and keep the temperature constant, set the stirring speed to 1000 rpm, and slowly add solution B dropwise under high-speed stirring, and keep the reaction at a constant temperature for 20 min. After the first stage of reaction is completed, raise the temperature of the reaction system to 150 ℃, and continue to keep the reaction at this temperature under reflux for 30 min to complete the crystallization and growth process. After the reaction is completed, stop heating and stirring, and let the reaction mixture cool down to room temperature naturally.

[0053] (3) The solid precipitate in the system was collected by centrifugation (26,000 rpm, 20 min). The precipitate was washed three times with anhydrous ethanol to remove residual organic solvent and impurity ions. The washed solid sample was transferred to a vacuum oven and dried at 60 °C for 6 h to obtain basic copper nitrate Cu4(NO3)2(OH)6.

[0054] (4) Weigh 10 mg of Cu4(NO3)2(OH)6 powder and disperse it in a mixed solution consisting of 460 μL isopropanol and 80 μL Nafion solution. After ultrasonic treatment for 30 minutes, a uniform catalyst ink is formed. Subsequently, the catalyst ink is uniformly sprayed onto carbon paper with a gas diffusion layer using a spray gun, and then dried at room temperature to remove surface moisture.

[0055] (5) Hydrophobic carbon paper loaded with Cu4(NO3)2(OH)6 was placed in 1.0 mol / L KOH electrolyte as the working electrode and connected to an electrochemical workstation. Nickel foam was used as the counter electrode, and Ag / AgCl (saturated KCl) was used as the reference electrode. The pulse program was set as follows: anode potential of 0.6 V for 20 s, cathode potentials of -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 20 s, with a total cycle time of 30 min. The electrochemical workstation was started to perform pulse electrocatalytic treatment, and the corresponding Faraday efficiency was tested simultaneously. The results are as follows: Figure 1 As shown.

[0056] Example 2

[0057] (1) Weigh 300 mg of copper nitrate trihydrate solid and add it to 30 mL of diethylene glycol diethyl ether solvent. Stir thoroughly until completely dissolved to prepare precursor solution A for later use. Separately weigh 100 mg of sodium bicarbonate and dissolve it in a pre-prepared mixed solvent (10 mL diethylene glycol + 2 mL deionized water). Stir until dissolved evenly to obtain alkaline precursor solution B.

[0058] (2) Place the prepared solution A in a heating and stirring apparatus, heat it to 100 ℃ and keep the temperature constant, set the stirring speed to 1000 rpm, and slowly add solution B dropwise under high-speed stirring, and keep the reaction at a constant temperature for 20 min. After the first stage of reaction is completed, raise the temperature of the reaction system to 150 ℃, and continue to keep the reaction at this temperature under reflux for 30 min to complete the crystallization and growth process. After the reaction is completed, stop heating and stirring, and let the reaction mixture cool down to room temperature naturally.

[0059] (3) The solid precipitate in the system was collected by centrifugation (26,000 rpm, 20 min). The precipitate was washed three times with anhydrous ethanol to remove residual organic solvent and impurity ions. The washed solid sample was transferred to a vacuum oven and dried at 60 °C for 6 h to finally obtain basic copper nitrate Cu4(NO3)2(OH)6.

[0060] (4) Weigh 10 mg of Cu4(NO3)2(OH)6 powder and disperse it in a mixed solution consisting of 460 μL isopropanol and 80 μL Nafion solution. After ultrasonic treatment for 30 minutes, a uniform catalyst ink is formed. Subsequently, the catalyst ink is uniformly sprayed onto carbon paper with a gas diffusion layer using a spray gun, and then dried at room temperature to remove surface moisture.

[0061] (5) Hydrophobic carbon paper loaded with Cu4(NO3)2(OH)6 was placed in 1.0 mol / L KOH electrolyte as the working electrode and connected to an electrochemical workstation. Nickel foam was used as the counter electrode, and Ag / AgCl (saturated KCl) was used as the reference electrode. The pulse program was set as follows: anode potential of 1.2 V for 10 s, cathode potentials of -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 10 s, with a total cycle time of 30 min. The electrochemical workstation was started to perform pulse electrocatalytic treatment, and the corresponding Faraday efficiency was tested. The results are as follows. Figure 2 As shown.

[0062] Example 3

[0063] This embodiment uses the same method as Example 1 to prepare the catalyst, the difference being that the pulse program in this embodiment is as follows: anode potential 0.6 V for 10 s, cathode potentials -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 10 s, with a total cycle time of 30 min. The measured Faraday efficiency diagram is shown below. Figure 3 As shown.

[0064] Example 4

[0065] This embodiment uses the same method as Example 1 to prepare the catalyst, the difference being that the pulse program in this embodiment is as follows: anode potential 0.6 V for 30 s, cathode potentials -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 30 s, with a total cycle time of 30 min. The measured Faraday efficiency diagram is shown below. Figure 4 As shown.

[0066] Example 5

[0067] This embodiment uses the same method as Example 2 to prepare the catalyst, the difference being that the pulse program in this comparative example is: anode potential 1.2 V for 20 s, cathode potentials -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 20 s, with a total cycle time of 30 min. The measured Faraday efficiency diagram is shown below. Figure 5 As shown.

[0068] Example 6

[0069] This embodiment uses the same method as Example 2 to prepare the catalyst, the difference being that the pulse program in this embodiment is as follows: anode potential 1.2 V for 30 s, cathode potentials -1.0 V, -1.2 V, -1.4 V, -1.6 V, and -1.8 V for 30 s, with a total cycle time of 30 min. The measured Faraday efficiency diagram is shown below. Figure 6 As shown.

[0070] Comparative Example 1

[0071] The preparation process of this comparative catalyst is consistent with that of Examples 1 and 2, except that the CO2RR reduction product detection was performed under constant voltage electroreduction conditions. Its Faraday efficiency diagram is shown below. Figure 7 As shown.

[0072] Depend on Figure 1 , 3 As shown in Figures 4 and 5, when the anode potential is 0.6 V, ethylene is the main reduction product when the cathode potential is in the range of -1.0 to -1.8 V, and the ethylene selectivity reaches its highest value (52.5%) at -1.4 V. Methane, on the other hand, has extremely low selectivity and is practically undetectable at all cathode test voltages, indicating that the methane formation pathway is significantly suppressed at this anode potential. In contrast... Figure 1 , 3 As can be seen from point 4, at an anode potential of E... a =0.6 V, fixed cathode potential (E c Under pulsed electrolysis conditions of -1.4 V, the pulse duration significantly modulates the Faradaic efficiency of CO2RR electroreduction products. When the pulse duration is 10 s, due to insufficient oxidation cycle, it is difficult to stably form efficient Cu on the catalyst surface. 0 / Cu + The active sites result in a low Faradaic efficiency for the C2H4 product. When the pulse time is extended to 20 s, the catalyst can achieve moderate in-situ oxidation and reconstruction, stably maintaining Cu. 0 / Cu + The active site and high *CO intermediate coverage significantly promote the C–C coupling reaction, enabling the C2H4 Faradaic efficiency to reach a maximum of 52.5%, while the CH4 and H2 byproducts are significantly suppressed. Further increasing the pulse time to 30 s leads to over-oxidation and catalyst surface structural reorganization, resulting in a slight decrease in C2H4 selectivity at low potentials, but the main product remains C2H4, with almost no detectable CH4.

[0073] Depend on Figure 2 , 5As can be seen from Figures 6 and 7, the selectivity of C2H4 products is significantly suppressed at an anode potential of 1.2 V, and generally decreases with a negative shift in the cathode potential. Conversely, at this anode potential, the CH4 yield gradually increases, and the Faraday efficiency of CH4 reaches its highest value (43.05%) at -1.6 V. Figure 2 , 5 The comparison of 6 shows that at the anode potential E a =1.2 V, fixed cathode potential (E c Under pulsed electrolysis conditions (-1.6 V), this catalytic system primarily undergoes deep hydrogenation, with CH4 as the core product, while C2H4 formation is significantly suppressed. At a pulse duration of 10 s, the catalyst surface is precisely controlled to form a high-valence active site interface rich in Cu⁺ / Cu²⁺, effectively promoting continuous protonation and deep hydrogenation of the *CO intermediate, resulting in a maximum CH4 Faradaic efficiency of 43.05%, while C2H4 is significantly suppressed and the hydrogen evolution side reaction remains at a low level. As the pulse duration increases to 20 s and 30 s, excessive redox cycling leads to excessive remodeling of the catalyst surface, causing a significant decrease in CH4 Faradaic efficiency, while the hydrogen evolution reaction intensifies, becoming the main competing side reaction. Simultaneously, multi-carbon products such as C2H4 maintain extremely low Faradaic efficiencies at all three pulse durations, indicating that the C–C coupling pathway is significantly suppressed under these conditions, and the reaction strictly follows the methane formation pathway. Pulse parameter control suggests that the anolyte potential dominates the switching between the C–C coupling and hydrogenation pathways.

[0074] like Figure 7 As shown, constant voltage electrolysis has significant limitations compared to pulsed electrolysis: it cannot dynamically control the valence state of copper active sites and it is difficult to stabilize Cu. 0 / Cu + Uncontrollable interface and key intermediate *CO coverage, coupled with catalyst deactivation due to excessive reduction, ultimately lead to a fixed product distribution and an inability to selectively switch between C2H4 and CH4. 2+ The product's Faraday efficiency is significantly lower than that of the pulsed system.

Claims

1. A method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential, characterized in that, include: A flow electrolytic cell was used, with nickel foam as the counter electrode, Ag / AgCl as the reference electrode, carbon paper with a basic copper nitrate catalyst sprayed on its surface as the working electrode, and potassium hydroxide solution as the electrolyte. The electrocatalytic reduction of carbon dioxide was carried out using pulse potential, and the selectivity of methane and ethylene in the reduction products was controlled by adjusting the pulse potential and pulse time.

2. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 1, characterized in that, The anode potential is set to 0.4~0.8 V to increase ethylene production while suppressing methane production.

3. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 1, characterized in that, The anode potential is set to 1~1.4 V to increase methane formation while suppressing ethylene formation.

4. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 1, characterized in that, The duration of a single pulse is 5~35 s, and the alternation period is 10~70 s; The ratio of the duration of the cathode potential to that of the anode potential is 1:

1.

5. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 1, characterized in that, The preparation method of the basic copper nitrate catalyst is as follows: (1) Dissolve copper nitrate trihydrate in diethylene glycol diethyl ether to obtain solution A; (2) Dissolve sodium bicarbonate in a mixed solvent consisting of diethylene glycol and deionized water to obtain solution B; (3) Heat solution A and slowly add solution B under stirring to keep the temperature for reaction, then raise the temperature and continue the reaction. After the reaction is completed, the basic copper nitrate catalyst is obtained by post-treatment.

6. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 5, characterized in that, The mass-to-volume ratio of copper nitrate trihydrate to diethylene glycol diethyl ether is 8-12 mg / mL; The mass-to-volume ratio of sodium bicarbonate to the mixed solvent is 7-10 mg / mL; The volume ratio of diethylene glycol to deionized water in the mixed solvent is (4~6):1; The mass ratio of copper nitrate trihydrate to sodium bicarbonate is (2~4):

1.

7. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 5, characterized in that, In step (3), the temperature of the heat preservation reaction is 80~120 ℃, and the reaction time is 10~30 min; After heating, the reaction continues at a temperature of 100~200 ℃ for a reaction time of 20~40 min.

8. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 5, characterized in that, In step (3), the post-processing procedure is as follows: The solid precipitate in the system was collected by centrifugation and washed three times with anhydrous ethanol, followed by vacuum drying to obtain the basic copper nitrate catalyst.

9. The method for controlling the selectivity of electrocatalytic carbon dioxide reduction products by pulse potential according to claim 1, characterized in that, The concentration of potassium hydroxide solution is 0.5~1.5 mol / L.

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