A catalyst for carbon dioxide electro-reduction to ethylene and a preparation method and application thereof

Abstract

The application provides a catalyst for carbon dioxide electro-reduction to ethylene and a preparation method and application thereof, adopts a multi-step self-assembly strategy, gradually constructs an Ag-N-C carrier structure and regulates spatial distribution of Cu nanoparticles and Pd monomers, realizes synergic construction of Ag monomer atom sites, Cu active sites and Pd monomer atom regulating sites, and thus forms a Pd1Cu / Ag-N-C catalytic system with multi-site division and electronic complementary effect. The catalyst shows significantly improved catalytic activity, selectivity and running stability in the process of carbon dioxide electro-reduction to ethylene. The preparation route is clear, operability is strong, component regulation is accurate, is suitable for various carbon-based carrier systems, and has good potential for large-scale preparation and application prospect in industrialization.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and in particular relates to a catalyst for the electroreduction of carbon dioxide to ethylene, its preparation method and application. Background Technology

[0002] The electroreduction of carbon dioxide to produce multi-carbon products has high industrial application potential, with ethylene being one of the important target products. Existing copper-based catalysts typically rely on the symmetrical dimerization of *CO and *CO to form C-C bonds, a pathway with a high energy barrier that limits ethylene selectivity. Furthermore, in existing systems, CO generation and protonation usually occur at the same type of catalytic site, where electron demand, proton supply, and intermediate steady-state distribution are coupled, making it difficult to simultaneously achieve high *CO coverage and efficient protonation. Therefore, these catalytic systems generally suffer from the technical bottleneck of not being able to simultaneously satisfy CO generation efficiency, proton supply capacity, and C-C coupling efficiency, and ethylene selectivity still needs improvement.

[0003] Existing technologies (such as Pr single-atom alloys) have attempted to promote asymmetric coupling by enhancing water dissociation, but these strategies rely on external promoters and do not address the key issue of how to achieve functional differentiation on the Cu surface itself to simultaneously optimize CO adsorption and CHO formation. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the deficiencies in the prior art and proposes a catalyst for the electroreduction of carbon dioxide to ethylene, its preparation method and application.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: In a first aspect, the present invention provides a method for preparing a catalyst for the electroreduction of carbon dioxide to ethylene, comprising the following steps: S1. A nitrogen-containing mesoporous carbon support with nitrogen-containing sites, stable channels, and conductive carbon framework was prepared by using a nanoemulsion self-assembly process and a pyrolysis process under an inert atmosphere. S2. Dissolve the silver source precursor in an alcoholic solvent to prepare solution A. Immerse the nitrogen-containing mesoporous carbon support obtained in step S1 in solution A. After drying, heat-treat in an inert atmosphere to anchor Ag to the carbon framework in an Ag-N coordination manner to obtain Ag-NC. S3. Dissolve the copper source precursor in an alcoholic solvent to prepare solution B. Dissolve the Ag-NC obtained in step S2 in an alcoholic solvent and immerse it in solution B. After drying, perform heat treatment under a reducing atmosphere to reduce the copper precursor to form Cu nanodomains and obtain Cu / Ag-NC. S4. Disperse Cu / Ag-NC in an alcoholic solvent, slowly add a palladium source precursor solution to induce a displacement reaction, collect, wash and dry the product to obtain a catalyst for the electroreduction of carbon dioxide to produce ethylene, denoted as Pd1Cu / Ag-NC.

[0006] Preferably, in step S1, a nitrogen-containing mesoporous carbon carrier is prepared by sequentially using dopamine, block copolymer, and pore-forming agent as raw materials and employing a nanoemulsion self-assembly process and a pyrolysis process.

[0007] Preferably, the nanoemulsion self-assembly process in step S1 includes the following steps: After dissolving the block copolymer and dopamine in a solvent, a pore-forming agent was slowly injected and stirred to form composite monomolecular micelles. After stirring continued, concentrated ammonia was added dropwise. After the reaction was completed, the polydopamine nanospheres were collected and washed.

[0008] Preferably, the mass ratio of the block copolymer to dopamine is 1:(2-3).

[0009] Preferably, the amount of the porogen is 2.0-3.4% of the volume of the reaction system.

[0010] Preferably, the block copolymer is a polyoxyethylene polyoxypropylene ether block copolymer.

[0011] Preferably, the porogen is tetramethylbenzidine.

[0012] Preferably, the amount of concentrated ammonia used should meet the requirement that the mass percentage of ammonia in the reaction system is 0.8-1.3%.

[0013] Preferably, the pyrolysis process in step S1 includes the following two-stage heat treatment: the first stage is treated at 350-450℃ for 2-5 hours; the second stage is treated at 700-800℃ for 2-5 hours; the heating rate is 1-5℃ / min.

[0014] Preferably, the silver source precursor in step S2 is selected from AgNO3 and / or CH3COOAg. More preferably, it is AgNO3.

[0015] Preferably, the concentration of the silver source precursor in solution A in step S2 is less than 0.012 mol / L.

[0016] Preferably, the soaking time in step S2 is 8-12 hours.

[0017] Preferably, the drying temperature in step S2 is 50-80 °C; Preferably, the heat treatment in step S2 is performed at a temperature of 700-800 ℃ for 2-5 h.

[0018] Preferably, the inert atmosphere in step S2 is argon or nitrogen.

[0019] Preferably, the copper source in step S3 is selected from one or more of CuCl2·2H2O, Cu(NO3)2, CuSO4, and Cu(CH3COO)2. More preferably, it is CuCl2·2H2O.

[0020] Preferably, the concentration of the copper source in solution B in step S3 is 3-10 mM.

[0021] Preferably, the soaking time in step S3 is 8-12 hours.

[0022] Preferably, the drying temperature in step S3 is 50-80 ℃.

[0023] Preferably, the reducing atmosphere in step S3 is an H2 / Ar mixture, wherein the volume fraction of H2 is 5%.

[0024] Preferably, the heat treatment temperature in step S3 is 300-400 ℃.

[0025] Preferably, the palladium source precursor solution in step S4 is selected from one or more of PdCl2, Pd(NO3)2, and Pd(CH3COO)2. More preferably, it is PdCl2.

[0026] Preferably, the concentration of the palladium source precursor solution in step S4 is 0.5-5 mM; Preferably, the displacement reaction time in step S4 is 1-5 hours; the drying temperature is 50-80°C.

[0027] Secondly, the present invention provides a catalyst prepared by the above-described preparation method.

[0028] Thirdly, the present invention also provides the application of the above-mentioned catalyst in the electrocatalytic CO2 reduction reaction.

[0029] Preferably, the electrocatalytic CO2 reduction reaction is carried out in a flowing electrolyzer system.

[0030] This invention proposes for the first time a strategy to achieve "atomic-level functional partitioning" (Pd-nearby sites and Pd-far-from-Cu sites) on the Cu surface through the intercalation of heterometallic single-atom Pd. This invention constructs a bifunctional structure on a nitrogen-doped carbon framework, consisting of an "Ag-NC CO-generating domain and a Pd1Cu hydrogenation / coupling domain": the Ag-NC sites continuously and efficiently generate *CO and directionally transport it to the metal Cu domain; the Pd single-atom intercalation into Cu nanoparticles induces local electronic structure reconstruction, causing the Cu surface to spontaneously differentiate into Pd-nearby Cu sites (facilitating the first step of *CO → *CHO hydrogenation) and Pd-far-from-Cu sites (facilitating steady-state *CO adsorption). These two types of functionally complementary sites work synergistically on the same Cu surface, enabling the generated *CHO to undergo asymmetric *CO-*CHO coupling with the neighboring, highly covered *CO in the optimal configuration. This fundamentally solves the bottleneck problem of limited *CO-*CO symmetric coupling and low C2H4 selectivity in traditional Cu catalysts.

[0031] Furthermore, since the Ag-NC CO-forming region and the Pd1Cu reaction region are spatially adjacent, this invention enables continuous CO supply and subsequent hydrogenation / coupling steps to proceed sequentially within the same system, thereby improving the selectivity of C2H4. Simultaneously, this structure eliminates the need for external co-catalysts or complex multiphase interfaces; reaction regions with different functions can be formed through atomic-level control within the Cu matrix.

[0032] In the process of CO2 electroreduction to ethylene, the bottleneck is concentrated in key elementary steps such as CO generation, CO→CHO proton coupling and subsequent CC coupling: if "CO generation-hydrogenation-coupling" are carried out simultaneously at the same site, it is difficult to balance the steady-state coverage of CO and the local proton supply, and the channel is prone to slide toward symmetrical CO-CO dimerization and C1 byproducts.

[0033] This invention constructs a bifunctional structure on a nitrogen-doped carbon framework, consisting of an "Ag-NC CO-generating domain and a Pd1Cu hydrogenation / coupling domain": Ag-NC sites are continuously and controllably generated and epitaxially supplied with CO; Pd single atoms are embedded in the Cu lattice to induce surface electronic heterogeneity, forming two types of cooperative sites: Pd-near Cu (accelerating CO → CHO) and Pd-far from Cu (stabilizing additional CO), achieving a sequential progression of "in-situ generation-in-situ conversion-in-situ coupling" at the three-phase interface.

[0034] Compared to traditional single-site strategies, this specialized coupling structure simultaneously improves H coverage and CO accessibility at the operating potential, preferentially triggering asymmetric CO-CHO coupling and significantly enhancing C2H4 selectivity and the C2 / C1 ratio. Combined with the rapid gas transfer of a flow-through electrolyzer, this system maintains low polarization while stably outputting high-throughput ethylene, achieving path reconstruction and performance amplification driven by a synergistic structure-electronics-interface approach.

[0035] Compared with the prior art, the present invention has the following advantages: (1) This invention realizes the "site division of labor" in electrocatalysis: decoupling CO generation from hydrogenation / coupling space, alleviating competition at the same site, and improving CO utilization efficiency; (2) This invention achieves electronic heterogeneity regulation: Pd single-atom-induced electronic heterogeneity of Cu surface, synergistically enhances CO → CHO protonation and coupling; (3) The present invention achieves improved path selectivity: preferential asymmetric CO-CHO coupling significantly improves C2H4 selectivity and C2 / C1 ratio, and suppresses C1 byproducts; (4) The present invention achieves a simple and controllable process: solution impregnation + conventional heat treatment + mild replacement, with a wide parameter window, reproducibility and scalability; (5) The present invention achieves high device matching: the GDE three-phase interface is compatible with the flow-through electrolyzer, and high-throughput CO2 supply and on-site conversion of intermediates are achieved simultaneously, which is suitable for long-term stable operation. Attached Figure Description

[0036] Figure 1 The image shows the Pd1Cu / Ag-N-CSEM morphology of the catalyst prepared in Example 1 of this invention. Figure 2 The image shows a HAADF-STEM image of the catalyst Pd1Cu / Ag-NC prepared in Example 1 of this invention. Figure 3 The image shows a HAADF-STEM image of the catalyst Pd1Cu / Ag-NC prepared in Example 1 of this invention, where the dashed circles represent atomically dispersed Ag. Figure 4 This is a HAADF-STEM image of the catalyst Pd1Cu / Ag-NC prepared in Example 1 of this invention. The dashed circles in the image represent isolated Pd atoms embedded in the Cu lattice. Figure 5 (a) is a selectivity diagram of CO2 electroreduction products of the 2%Pd1Cu / 1%Ag-NC catalyst prepared in Example 1 of this invention. (b) is a LSV diagram of the 2%Pd1Cu / 1%Ag-NC catalyst. Figure 6 The image shows the selectivity of CO2 electroreduction products of the 2%Pd1Cu / 0.5%Ag-NC catalyst prepared in Example 2 of this invention. Figure 7 This is a selectivity diagram of CO2 electroreduction products of the 2%Pd1Cu / 2%Ag-NC catalyst prepared in Example 3 of the present invention; Figure 8This is a selectivity diagram of CO2 electroreduction products of the 2%Pd1Cu / 3%Ag-NC catalyst prepared in Example 4 of this invention; Figure 9 This is a selectivity diagram of CO2 electroreduction products of the 1%Pd1Cu / 1%Ag-NC catalyst prepared in Example 5 of the present invention; Figure 10 This is a selectivity diagram of CO2 electroreduction products of the 4%Pd1Cu / 1%Ag-NC catalyst prepared in Example 6 of the present invention; Figure 11 This is a selectivity diagram of CO2 electroreduction products of the 2% Pd1Cu / NC catalyst prepared in Comparative Example 1 of this invention; Figure 12 (a) is a selectivity diagram of CO2 electroreduction products of the Cu / 1%Ag-NC catalyst prepared in the comparative example of the present invention, and (b) is a LSV diagram of the Cu / 1%Ag-NC catalyst. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0038] In this document, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0040] In this article, the terms "multiple" or "more than" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0041] In this document, the terms "preferred" and "more preferred" are used only to describe implementation methods or embodiments with better effects, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0042] In this document, terms such as "further" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0043] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0044] In this document, the term "about" means a specified value of + / - 10%, preferably + / - 5%, and more preferably + / - 1%.

[0045] In this article, the terms “include,” “including,” “have,” “contain,” etc., are all open-ended terms, meaning that they include but are not limited to.

[0046] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0047] This invention provides a method for preparing a catalyst for the electroreduction of CO2 to ethylene, comprising the following steps: S1, Constructing a nitrogen-containing carbon matrix Nitrogen-containing mesoporous carbon supports were prepared by nanoemulsion self-assembly and pyrolysis under an inert atmosphere to introduce nitrogen-containing sites such as pyridine / graphite N and obtain stable channels and conductive carbon framework, thereby improving the anchoring strength of noble / transition metals and the wettability of the gas-electrolyte three-phase interface.

[0048] S2, Constructing Ag-NC coordination sites The silver source precursor is dissolved in an alcoholic solvent to prepare solution A. The nitrogen-containing carbon support treated in step S1 is immersed in solution A, dried, and then heat-treated in an inert atmosphere to anchor Ag in the carbon framework in an Ag-N coordination manner to form Ag-NC, which is used to preferentially generate and continuously supply the *CO intermediate in the reaction.

[0049] S3, Introduction of Cu nanodomains The copper precursor was dissolved in an alcoholic solvent to prepare solution B. The Ag-NC obtained in step S2 was dissolved in the alcoholic solvent and then immersed in solution B. After drying, it was heat-treated under a reducing atmosphere to reduce the copper precursor to form Cu nanodomains, thus obtaining Cu / Ag-NC.

[0050] S4, Pd single-atom embedding Cu / Ag-NC was dispersed in an alcoholic solvent, and a palladium source precursor solution was slowly added. Through an electrostatic ion exchange process, Pd was inserted into the Cu lattice in a single-atom manner. After collecting, washing, and drying the product, a catalyst for the electroreduction of carbon dioxide to ethylene was obtained in which Pd1Cu nanodomains and Ag-NC sites coexist in the same matrix. This catalyst is denoted as Pd1Cu / Ag-NC.

[0051] Preferably, in step S1, a nitrogen-containing mesoporous carbon carrier is prepared by sequentially using dopamine, block copolymer, and pore-forming agent as raw materials and employing a nanoemulsion self-assembly process and a pyrolysis process.

[0052] Preferably, the nanoemulsion self-assembly process in step S1 includes the following steps: After dissolving the block copolymer and dopamine in a solvent, a pore-forming agent was slowly injected and stirred to form composite monomolecular micelles. After stirring continued, concentrated ammonia was added dropwise. After the reaction was completed, the polydopamine nanospheres were collected and washed.

[0053] Preferably, the mass ratio of the block copolymer to dopamine is 1:(2-3).

[0054] Preferably, the amount of the porogen is 2.0-3.4% of the volume of the reaction system.

[0055] Preferably, the block copolymer is a polyoxyethylene polyoxypropylene ether block copolymer.

[0056] Preferably, the porogen is tetramethylbenzidine.

[0057] Preferably, the amount of concentrated ammonia used should meet the requirement that the mass percentage of ammonia in the reaction system is 0.8-1.3%.

[0058] Preferably, the pyrolysis process in step S1 includes the following two-stage heat treatment: the first stage is treated at 350-450℃ for 2-5 hours; the second stage is treated at 700-800℃ for 2-5 hours; the heating rate is 1-5℃ / min.

[0059] Preferably, the silver source precursor in step S2 is selected from one or more of AgNO3 and CH3COOAg. More preferably, it is AgNO3.

[0060] Preferably, the concentration of the silver source precursor in solution A in step S2 is less than 0.012 mol / L.

[0061] Preferably, the soaking time in step S2 is 8-12 hours.

[0062] Preferably, the drying temperature in step S2 is 50-80°C.

[0063] Preferably, the heat treatment temperature in step S2 is 700-800℃, and the time is 2-5 hours.

[0064] Preferably, the inert atmosphere in step S2 is argon or nitrogen.

[0065] Preferably, the copper source in step S3 is selected from one or more of CuCl2·2H2O, Cu(NO3)2, CuSO4, and Cu(CH3COO)2. More preferably, it is CuCl2·2H2O.

[0066] Preferably, the concentration of the copper source in solution B in step S3 is 3-10 mM.

[0067] Preferably, the soaking time in step S3 is 8-12 hours.

[0068] Preferably, the drying temperature in step S3 is 50-80 ℃.

[0069] Preferably, the reducing atmosphere in step S3 is an H2 / Ar mixture, wherein the volume fraction of H2 is 5%.

[0070] Preferably, the heat treatment temperature in step S3 is 300-400 ℃.

[0071] Preferably, the palladium source precursor solution in step S4 is selected from one or more of PdCl2, Pd(NO3)2, and Pd(CH3COO)2. More preferably, it is PdCl2.

[0072] Preferably, the concentration of the palladium source precursor solution in step S4 is 0.5-5 mM.

[0073] Preferably, the displacement reaction time in step S4 is 1-5 hours; the drying temperature is 50-80°C.

[0074] Secondly, the present invention provides a catalyst prepared by the above-described preparation method.

[0075] Thirdly, the present invention also provides the application of the above-mentioned catalyst in the electrocatalytic CO2 reduction reaction.

[0076] The present invention will be described in detail below with reference to the embodiments.

[0077] Example 1: 2%Pd1Cu / 1%Ag-NC catalyst The preparation method of the 2%Pd1Cu / 1%Ag-NC catalyst is as follows: S1. 0.5 g of Pluronic F127 and 1 g of dopamine (DA) were dissolved in 10 mL of a 1:1 volume ratio water / ethanol mixture, and stirred continuously at room temperature for 30 min. Then, 250 μL of TMB was slowly injected into the solution, and the system was stirred at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, 375 μL of concentrated ammonia (28% by mass) was added dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continued for 6 h, the obtained MPDA nanospheres were collected by centrifugation and washed at least three times with deionized water and ethanol. Finally, the MPDA nanospheres were heated to 350 °C in an Ar atmosphere at a heating rate of 1 °C / min and held for 3 h, followed by heating to 800 °C at the same heating rate and holding for 2 h to obtain nitrogen-containing mesoporous carbon supports (MCNs).

[0078] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 7 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 12 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 70 °C, and then heated to 800 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 2 h. The resulting product was designated as 1% Ag-NC.

[0079] S3. 100 mg of 1% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60°C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400°C at a heating rate of 5°C / min and held for 2 h to obtain the Cu / 1% Ag-NC composite material.

[0080] S4. 100 mg of Cu / 1%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 1%Ag-NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 3 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 60 °C for 12 h. The resulting sample is the 2%Pd1Cu / 1%Ag-NC catalyst of this invention.

[0081] Figure 1 The SEM characterization results are for the 2%Pd1Cu / 1%Ag-NC catalyst. Figure 2 HAADF-STEM with 2% Pd1Cu / 1% Ag-NC; Figure 3 HAADF-STEM image of 2%Pd1Cu / 1%Ag-NC, with red dashed circles representing atomically dispersed Ag; Figure 4 The image is a HAADF-STEM image of 2%Pd1Cu / 1%Ag-NC, with orange dashed circles indicating isolated Pd atoms embedded in the Cu lattice.

[0082] Figure 5 This study demonstrates the CO2 electroreduction performance of the 2%Pd1Cu / 1%Ag-NC catalyst in a flow electrolyzer system. At -0.97 V vs. RHE potential, the catalyst exhibits excellent C2H4 product selectivity, with an ethylene Faradaic efficiency as high as 78.8%. Figure 5 b is the LSV diagram of the 2%Pd1Cu / 1%Ag-NC catalyst. At -1.2 V vs. RHE potential, the current density of this catalyst can reach -900 mA / cm². 2 .

[0083] Example 2: 2%Pd1Cu / 0.5%Ag-NC catalyst The preparation method of the 2%Pd1Cu / 0.5%Ag-NC catalyst is as follows: S1. Dissolve 0.5 g of Pluronic F127 and 1 g of dopamine (DA) in 10 mL of a 1:1 volume ratio water / ethanol mixture and stir continuously at room temperature for 30 min. Then, slowly inject 250 μL of TMB into the solution and stir at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, add 375 μL of concentrated ammonia (28% by mass) dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continues for 6 h, collect the obtained MPDA nanospheres by centrifugation and wash them at least three times with deionized water and ethanol. Finally, heat the MPDA nanospheres in an Ar atmosphere to 350 °C at a heating rate of 1 °C / min and hold for 3 h, then heat to 800 °C at the same heating rate and hold for 2 h to obtain nitrogen-containing mesoporous carbon supports (MCNs).

[0084] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 3.5 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 12 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 70 °C, and then heated to 800 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 2 h. The resulting product was designated as 0.5% Ag-NC.

[0085] S3. 100 mg of 0.5% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and stirring was continued vigorously. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the Cu / 0.5% Ag-NC composite material.

[0086] S4. 100 mg of Cu / 0.5%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 0.5%Ag-NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 3 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 60 °C for 12 h. The resulting sample is the 2%Pd1Cu / 0.5%Ag-NC catalyst of this invention.

[0087] Figure 6 The CO2 electroreduction performance of the 2%Pd1Cu / 0.5%Ag-NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE potential, the C2H4 selectivity of this catalyst was 54.0%, significantly lower than that of the 2%Pd1Cu / 1%Ag-NC catalyst. When the Ag loading is low, the *CO flux is insufficient, preventing the Pd1Cu domain from fully entering the optimal reaction state with high *CO coverage.

[0088] Example 3: 2%Pd1Cu / 2%Ag-NC catalyst The preparation method of the 2%Pd1Cu / 2%Ag-NC catalyst is as follows: S1. Dissolve 0.5 g of Pluronic F127 and 1 g of dopamine (DA) in 10 mL of a 1:1 volume ratio water / ethanol mixture and stir continuously at room temperature for 30 min. Then, slowly inject 250 μL of TMB into the solution and stir at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, add 375 μL of concentrated ammonia (28% by mass) dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continues for 6 h, collect the obtained MPDA nanospheres by centrifugation and wash them at least three times with deionized water and ethanol. Finally, heat the MPDA nanospheres in an Ar atmosphere to 350 °C at a heating rate of 1 °C / min and hold for 3 h, then heat to 800 °C at the same heating rate and hold for 2 h to obtain nitrogen-containing mesoporous carbon supports (MCNs).

[0089] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 14 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 12 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 70 °C, and then heated to 800 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 2 h. The resulting product was designated as 2% Ag-NC.

[0090] S3. 100 mg of 2% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the Cu / 2% Ag-NC composite material.

[0091] S4. 100 mg of Cu / 2%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 2%Ag-NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 3 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 60 °C for 12 h. The resulting sample is the 2%Pd1Cu / 2%Ag-NC catalyst of this invention.

[0092] Figure 7The CO2 electroreduction performance of the 2%Pd1Cu / 2%Ag-NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE, the C2H4 selectivity of this catalyst was 65.3%, significantly lower than that of the 2%Pd1Cu / 1%Ag-NC catalyst. This result indicates that further increasing the Ag loading does not continuously enhance the selectivity of multi-carbon products; instead, it may cause a dynamic mismatch between CO generation and transfer rates. Specifically, the CO yield in the Ag-NC domain increases sharply with increasing Ag content, causing the local *CO coverage to exceed the coupling rate of the Pd1Cu domain, weakening the matching of *CO-*CHO coupling. Simultaneously, excess *CO may occupy active sites on the Cu surface, inhibiting the *CO → *CHO step at Pd adjacent Cu sites, thus reducing the efficiency of the key asymmetric coupling pathway.

[0093] Example 4: 2%Pd1Cu / 3%Ag-NC catalyst The preparation method of the 2%Pd1Cu / 3%Ag-NC catalyst is as follows: S1. 0.5 g of Pluronic F127 and 1 g of dopamine (DA) were dissolved in 10 mL of a 1:1 volume ratio water / ethanol mixture, and stirred continuously at room temperature for 30 min. Then, 250 μL of TMB was slowly injected into the solution, and the system was stirred at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, 375 μL of concentrated ammonia (28% by mass) was added dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continued for 6 h, the obtained MPDA nanospheres were collected by centrifugation and washed at least three times with deionized water and ethanol. Finally, the MPDA nanospheres were heated to 350 °C in an Ar atmosphere at a heating rate of 1 °C / min and held for 3 h, followed by heating to 800 °C at the same heating rate and holding for 2 h to obtain nitrogen-containing mesoporous carbon supports (MCNs).

[0094] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 21 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 12 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 70 °C, and then heated to 800 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 2 h. The resulting product was designated as 3% Ag-NC.

[0095] S3. 100 mg of 3% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the Cu / 3% Ag-NC composite material.

[0096] S4. 100 mg of Cu / 3%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 3%Ag-NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 3 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 60 °C for 12 h. The resulting sample is the 2%Pd1Cu / 3%Ag-NC catalyst of this invention.

[0097] Figure 8 The CO2 electroreduction performance of the 2%Pd1Cu / 3%Ag-NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE potential, the C2H4 selectivity of this catalyst was 42.4%, significantly lower than that of the 2%Pd1Cu / 1%Ag-NC catalyst. This result indicates that excessively high Ag loading disrupts the optimal synergistic ratio between Pd1Cu active sites and Ag-NC CO-forming sites, leading to *CO oversaturation or spatial configuration imbalance in the system. This inhibits the *CO → *CHO conversion efficiency at Pd-adjacent Cu sites, ultimately reducing the probability of asymmetric *CO-*CHO coupling.

[0098] Example 5: 1%Pd1Cu / 1%Ag-NC catalyst The preparation method of 1%Pd1Cu / 1%Ag-NC catalyst is as follows: S1. Dissolve 0.5 g of Pluronic F127 and 1 g of dopamine (DA) in 10 mL of a 1:1 volume ratio water / ethanol mixture and stir continuously at room temperature for 30 min. Then, slowly inject 350 μL of TMB into the solution and stir at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, add 515 μL of concentrated ammonia (28% by mass) dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continues for 6 h, collect the obtained MPDA nanospheres by centrifugation and wash them at least three times with deionized water and ethanol. Finally, heat the MPDA nanospheres in an Ar atmosphere to 450 °C at a heating rate of 5 °C / min and hold for 2 h, then heat to 700 °C at the same heating rate and hold for 5 h.

[0099] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 7 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 10 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 50 °C, and then heated to 700 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 4 h. The resulting product was designated as 1%Ag-NC.

[0100] S3. 100 mg of 1% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 10 h and dried overnight in a vacuum oven at 50 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the Cu / 1% Ag-NC composite material.

[0101] S4. 100 mg of Cu / 1%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 1%Ag-NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 5 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 50 °C for 12 h. The resulting sample is the 1%Pd1Cu / 1%Ag-NC catalyst of this invention.

[0102] Figure 9 The electroreduction performance of the 1%Pd1Cu / 1%Ag-NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE potential, the selectivity for C2H4 in this catalyst was 71.2%, significantly lower than that of the 2%Pd1Cu / 1%Ag-NC catalyst. This result indicates that lower Pd doping levels make it difficult to construct a sufficiently dense density of Pd-neighboring Cu sites, thereby limiting the protonation kinetics of *CO → *CHO and weakening its ability to promote asymmetric *CO-*CHO coupling.

[0103] Example 6: 4%Pd1Cu / 1%Ag-NC catalyst The preparation method of the 4%Pd1Cu / 1%Ag-NC catalyst is as follows: S1. Dissolve 0.5 g of Pluronic F127 and 1.5 g of dopamine (DA) in 10 mL of a 1:1 volume ratio water / ethanol mixture and stir continuously at room temperature for 30 min. Then, slowly inject 350 μL of TMB into the solution and stir at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, add 515 μL of concentrated ammonia (28% by mass) dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continues for 6 h, collect the obtained MPDA nanospheres by centrifugation and wash them at least three times with deionized water and ethanol. Finally, heat the MPDA nanospheres in an Ar atmosphere to 450 °C at a heating rate of 5 °C / min and hold for 3 h, then heat to 800 °C at the same heating rate and hold for 2 h to obtain nitrogen-containing mesoporous carbon supports (MCNs).

[0104] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 7 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 8 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 80 °C, and then heated to 700 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 5 h. The resulting product was designated as 1%Ag-NC.

[0105] S3. 100 mg of 1% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 8 h and dried overnight in a vacuum oven at 80 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere, heated to 300 °C at a heating rate of 5 °C / min, and held for 2 h to obtain the Cu / 1% Ag-NC composite material.

[0106] S4. 100 mg of Cu / 1%Ag-NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / 1%Ag-NC suspension to trigger the displacement reaction. The mixture was then stirred continuously for 5 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 80 °C for 12 h. The resulting product is the 4%Pd1Cu / 1%Ag-NC catalyst of this invention.

[0107] Figure 10 The CO2 electroreduction performance of the 4%Pd1Cu / 1%Ag-NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE potential, the C2H4 selectivity of this catalyst was 28.3%, significantly lower than that of the 2%Pd1Cu / 1%Ag-NC catalyst. This result indicates that the introduction of excess Pd disrupts the electronic structure equilibrium of the Cu surface, weakens the rational distribution of Pd-near / far from Cu sites, thereby inhibiting the effective promotion of CO → CHO and the asymmetric CO-CHO coupling pathway, ultimately leading to a significant decrease in C2H4 selectivity.

[0108] Comparative Example 1: 2% Pd1Cu / NC catalyst The preparation method of 2%Pd1Cu / NC catalyst is as follows: S1. Dissolve 0.5 g of Pluronic F127 and 1.5 g of dopamine (DA) in 10 mL of a 1:1 volume ratio water / ethanol mixture and stir continuously at room temperature for 30 min. Then, slowly inject 350 μL of TMB into the solution and stir at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, add 515 μL of concentrated ammonia (28% by mass) dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continues for 6 h, collect the obtained MPDA nanospheres by centrifugation and wash them at least three times with deionized water and ethanol. Finally, heat the MPDA nanospheres in an Ar atmosphere to 350 °C at a heating rate of 1 °C / min and hold for 3 h, then heat to 800 °C at the same heating rate and hold for 2 h to obtain the NC support.

[0109] S2. 100 mg of the NC support was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60 °C. Finally, the NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the Cu / NC composite material.

[0110] S3. 100 mg of Cu / NC was dispersed in 25 mL of ethanol solution and sonicated for 30 min. Then, a certain amount of PdCl2 (1.9 mM) was slowly added to the Cu / NC suspension to trigger the displacement reaction. The mixture was then continuously stirred for 12 h to ensure the reaction proceeded fully. The resulting black product was collected by centrifugation, washed three times with ethanol, and then dried under vacuum at 60 °C for 5 h. The resulting sample is the 2% Pd1Cu / NC catalyst of this invention.

[0111] Figure 11The CO2 electroreduction performance of the 2%Pd1Cu / NC catalyst in a flow electrolyzer system was demonstrated. At -0.97 V vs. RHE potential, the selectivity of C2H4 in this catalyst was 15.9%, significantly lower than that of 2%Pd1Cu / 1%Ag-NC. This result indicates that in the absence of Ag-NC CO-forming sites, the supply of CO intermediates in the system is limited, failing to form an effective synergy with Pd-induced Cu site differentiation, leading to hindered CC coupling kinetics and a significant decrease in C2H4 formation efficiency.

[0112] Comparative Example 2: Cu / 1%Ag-NC catalyst The preparation method of Cu / 1%Ag-NC catalyst is as follows: S1. Preparation of a nitrogen-containing carbon support: 0.5 g of Pluronic F127 and 1.5 g of dopamine (DA) were dissolved in 10 mL of a 1:1 volume ratio water / ethanol mixture, and stirred continuously at room temperature for 30 min. Then, 350 μL of TMB was slowly injected into the solution, and the system was stirred at 500 rpm to form F127 / TMB / DA composite monomolecular micelles. After stirring for 1 h, 515 μL of concentrated ammonia (28% by mass) was added dropwise to the above system to initiate DA polymerization and guide the micelles to self-assemble into mesoporous polydopamine (MPDA) nanospheres. After the reaction continued for 6 h, the obtained MPDA nanospheres were collected by centrifugation and washed at least three times with deionized water and ethanol. Finally, the MPDA nanospheres were heated to 350 °C in an Ar atmosphere at a heating rate of 1 °C / min and held for 3 h, followed by heating to 800 °C at the same heating rate and holding for 2 h.

[0113] S2. 100 mg of MCNs were dispersed in 25 mL of ethanol and stirred continuously for 30 min. Then, 7 mg of AgNO3 was dissolved in 10 mL of ethanol and stirred continuously for 30 min. Afterward, the AgNO3 ethanol solution was slowly added to the ethanol dispersion of MCNs, and the mixture was stirred continuously at room temperature for 12 h to ensure sufficient contact between the two. The resulting mixture was dried overnight in a vacuum oven at 70 °C, and then heated to 800 °C in a tube furnace under an Ar atmosphere at a heating rate of 5 °C / min and held for 2 h. The final sample was designated as 1%Ag-NC.

[0114] S3. 100 mg of 1% Ag-NC was dispersed in 25 mL of ethanol and stirred vigorously for 30 min. Then, 10 mL of ethanol solution containing 5.8 mM CuCl2·2H2O was slowly added to the Ag-NC suspension, and vigorous stirring continued. To ensure sufficient impregnation of CuCl2 on the Ag-NC support, the entire system was stirred continuously for 12 h and dried overnight in a vacuum oven at 60 °C. Finally, the Ag-NC with the adsorbed Cu precursor was placed in a 5% H2 / Ar atmosphere and heated to 400 °C at a heating rate of 5 °C / min and held for 2 h to obtain the final Cu / 1% Ag-NC composite material.

[0115] Figure 12 This study demonstrates the CO2 electroreduction performance of the Cu / 1%Ag-NC catalyst in a flowing electrolyzer system. At -0.97 V vs. RHE potential, the selectivity of this catalyst for C2H4 is 61.4%, which is significantly lower than that of 2%Pd1Cu / 1%Ag-NC. Figure 12 b is the LSV diagram of the Cu / 1%Ag-NC catalyst. At -1.2 V vs. RHE potential, the current density of this catalyst can reach -820 mA / cm². 2 These results indicate that while introducing Ag-NC to create CO sites on the Cu domain can improve C-C coupling efficiency to some extent, the lack of precise Pd single-atom control over the Cu surface electronic structure prevents the Cu sites from achieving atomic-level functional partitioning of Pd-nearby / Pd-faraway sites. This limits both the *CO → *CHO hydrogenation and *CO–*CHO asymmetric coupling processes. Therefore, the synergistic effect of the Ag-NC and Cu domain dual-site system is less than that of the multi-site coupling system formed after Pd embedding, further verifying that Pd-induced Cu site electronic heterogeneity is a key factor in achieving efficient C2H4 selectivity.

[0116] Comparing Examples 1-6 and Comparative Examples 1-2, it can be seen that the Pd1Cu / Ag-NC multi-site specialized coupling catalytic system constructed in this invention can significantly improve the catalytic activity of CO2 electroreduction to ethylene. The atomic-level Ag-N sites in the Ag-NC support can efficiently generate *CO intermediates, improving local CO coverage. Simultaneously, the Pd-proximal and Pd-distal bidifferentiated Cu sites formed by single-atom Pd embedding in the Cu domain can respectively promote the protonation and stable adsorption of *CO, thereby significantly reducing the energy barrier of asymmetric *CO-CHO coupling. The Pd1Cu / Ag-NC of this invention achieves effective specialization and synergistic coupling among *CO generation, proton supply, and CC coupling, avoiding the problems of insufficient CO coverage, low protonation efficiency, and limited coupling kinetics present in traditional single-active-site systems, thus improving the overall ethylene selectivity and catalytic stability.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for the electroreduction of carbon dioxide to ethylene, characterized in that: Includes the following steps: S1. A nitrogen-containing mesoporous carbon support with nitrogen-containing sites, stable channels, and conductive carbon framework was prepared by using a nanoemulsion self-assembly process and a pyrolysis process under an inert atmosphere. S2. Dissolve the silver source precursor in an alcoholic solvent to prepare solution A. Immerse the nitrogen-containing mesoporous carbon support obtained in step S1 in solution A. After drying, heat-treat in an inert atmosphere to anchor Ag to the carbon framework in an Ag-N coordination manner to obtain Ag-NC. S3. Dissolve the copper source precursor in an alcoholic solvent to prepare solution B. Dissolve the Ag-NC obtained in step S2 in an alcoholic solvent and immerse it in solution B. After drying, perform heat treatment under a reducing atmosphere to reduce the copper precursor to form Cu nanodomains and obtain Cu / Ag-NC. S4. Disperse Cu / Ag-NC in an alcoholic solvent, slowly add a palladium source precursor solution to induce a displacement reaction, collect, wash and dry the product to obtain a catalyst for the electroreduction of carbon dioxide to produce ethylene.

2. The preparation method according to claim 1, characterized in that: In step S1, a nitrogen-containing mesoporous carbon carrier is prepared by using dopamine, block copolymer, and porogen as raw materials, and then sequentially employing a nanoemulsion self-assembly process and a pyrolysis process.

3. The preparation method according to claim 2, characterized in that: The nanoemulsion self-assembly process in step S1 includes the following steps: After dissolving the block copolymer and dopamine in a solvent, a pore-forming agent is slowly injected and stirred to form composite monomolecular micelles. After stirring, concentrated ammonia is added dropwise. After the reaction is completed, the polydopamine nanospheres are collected and washed. Preferably, the pyrolysis process in step S1 includes the following two-stage heat treatment: the first stage is treated at 350-450℃ for 2-5 hours; the second stage is treated at 700-800℃ for 2-5 hours; the heating rate is 1-5℃ / min.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the block copolymer to dopamine is 1:(2-3); preferably, the amount of the porogen accounts for 2.0-3.4% of the volume of the reaction system; the block copolymer is selected as polyoxyethylene polyoxypropylene ether block copolymer; preferably, the porogen is selected as tetramethylbenzidine; preferably, the amount of concentrated ammonia water should meet the requirement that the mass percentage of ammonia accounts for 0.8-1.3% of the reaction system.

5. The preparation method according to claim 1, characterized in that: The silver source precursor in step S2 is selected from AgNO3 and / or CH3COOAg; more preferably AgNO3; preferably, the concentration of the silver source precursor in solution A in step S2 is less than 0.012 mol / L; preferably, the impregnation time in step S2 is 8-12 h; preferably, the drying temperature in step S2 is 50-80 ℃; preferably, the heat treatment temperature in step S2 is 700-800 ℃, and the time is 2-5 h; preferably, the inert atmosphere in step S2 is argon or nitrogen.

6. The preparation method according to claim 1, characterized in that: The copper source in step S3 is selected from one or more of CuCl2·2H2O, Cu(NO3)2, CuSO4, and Cu(CH3COO)2; more preferably, it is CuCl2·2H2O; preferably, the concentration of the copper source in solution B in step S3 is 3-10 mM.

7. The preparation method according to claim 1, characterized in that: The impregnation time in step S3 is 8-12 h; preferably, the drying temperature in step S3 is 50-80 ℃; preferably, the reducing atmosphere in step S3 is an H2 / Ar mixture, wherein the volume fraction of H2 is 5%; preferably, the heat treatment temperature in step S3 is 300-400 ℃.

8. The preparation method according to claim 1, characterized in that: The palladium source precursor solution in step S4 is selected from one or more of PdCl2, Pd(NO3)2, and Pd(CH3COO)2; more preferably, it is PdCl2; preferably, the concentration of the palladium source precursor solution in step S4 is 0.5-5 mM; preferably, the displacement reaction time in step S4 is 1-5 h; and the drying temperature is 50-80℃.

9. The application of the catalyst prepared by the method according to any one of claims 1-8 in the electrocatalytic CO2 reduction reaction.

10. The application according to claim 9, characterized in that: The electrocatalytic CO2 reduction reaction is carried out in a flow electrolysis cell system.

Images