A nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst and its preparation method and application

Abstract

The present invention discloses a preparation method of a nitrogen / sulfur co-doped porous carbon supported zinc single atom / metal copper tandem catalyst: dissolving a zinc salt in a solvent and then adding a 2-methylimidazole solution to obtain a zinc-based metal-organic framework precursor; then dispersing it in a solvent containing 5-amino-1,2,3-thiadiazole to obtain a sulfur-doped zinc-based metal-organic framework precursor; and then through calcination treatment, obtaining nitrogen / sulfur co-doped porous carbon supported zinc single atoms; sputtering a copper target onto a polytetrafluoroethylene film to obtain a polytetrafluoroethylene film supported copper nanoparticle substrate; spraying a dispersion of nitrogen / sulfur co-doped porous carbon supported zinc single atoms onto the surface of the polytetrafluoroethylene film supported copper nanoparticle substrate to obtain a nitrogen / sulfur co-doped porous carbon supported zinc single atom / metal copper tandem catalyst. The present invention also discloses the catalyst obtained by the above preparation method and its application as a working electrode in the electrocatalytic reduction of CO2 to prepare ethylene, showing excellent electrochemical activity and selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metal copper tandem catalyst, and a preparation method and application thereof. Background Art

[0002] The burning of fossil fuels has resulted in carbon dioxide (CO 2 ) Excessive accumulation of exhaust gas. The electroreduction reaction driven by renewable clean electricity is used to convert CO 2 Conversion into valuable chemicals is a promising approach that can not only reduce the accumulation of CO in the atmosphere, 2 , and can also produce chemicals with high added value. So far, researchers have focused on the electroreduction of CO 2 A lot of efforts have been made to prepare catalysts for the preparation of C1 and C2 products. CO, as a C1 product involving only two electron transfers, has the following advantages: (1) the reaction pathway is relatively simple, the reaction thermodynamic potential is low, and high selective conversion is easy to achieve; (2) as a gaseous product, it can be directly converted from CO 2 The CO2 gas can be directly used as a synthesis gas raw material and then used to produce C2 chemicals through the Fischer-Tropsch synthesis process.

[0003] Electrocatalytic reduction of CO 2 The key to producing CO products is to develop cheap, efficient and stable electrocatalysts. Precious metal-based catalysts have been shown to be effective for the electroreduction of CO. 2 The preparation of CO products has good selectivity and reactivity, but the high cost of noble metal-based catalysts limits their large-scale application. The current research results show that nitrogen-doped carbon-supported metal single atom catalysts can be used as an alternative material to noble metal-based catalysts for high-efficiency catalytic reduction of CO 2 Preparation of CO. For example, a Chinese patent document with publication number CN109652821A discloses a Ni-NC electrocatalyst, which prepares a Ni-NC electrocatalyst with high activity and selectivity by pyrolyzing a nickel-doped zinc-based metal organic framework precursor, and is applied to the reduction of CO. 2 CO was prepared, with the Faradaic efficiency of CO being greater than 92% over a wide range of applied voltages, and the highest CO partial current density reaching 71.5 mA cm -2 For example, Chinese patent document No. CN113118451A discloses a method for preparing a Mg single-atom catalyst and its application in electrocatalytic CO 2 The excellent performance of reducing CO is obtained by calcining a mixture of dicyandiamide, potassium chloride and sodium chloride. 3 N4 Nanosheets, and then C 3 N 4 The mixture of nanosheets, magnesium salt and carbon nanotubes is calcined to obtain a Mg single atom catalyst.

[0004] Copper-based catalysts are widely used in the electrochemical reduction of CO 2 Preparation of C2 products. For example, a Chinese patent document with publication number CN110548509A discloses a copper-based CO 2 Catalytic material and preparation method thereof, comprising: mixing an oxidant solution and an organic ligand solution to obtain a mixed solution; placing metallic copper in the mixed solution to allow the organic ligand to be adsorbed on some specific crystal faces of the metallic copper, and causing the crystal faces of the metallic copper not adsorbed by the organic ligand to undergo an oxidation reaction; washing the metallic copper after the oxidation reaction to remove the organic ligand adsorbed on the metallic copper crystal faces, and obtaining an OD-Cu catalytic material having more specific crystal faces after electrochemical reduction; the catalyst exhibits 40% electrocatalytic reduction of CO 2 The Faraday efficiency of preparing ethylene. For example, the Chinese patent document with publication number CN111636074A discloses a method for electrochemically reducing CO 2 Preparation and application of copper electrode for producing ethylene. Copper oxide with nanowire structure is grown on a substrate through chemical oxidation reaction, and then a thin layer of nanoparticles is grown on its surface through hydrothermal reaction. Surfactant and reducing agent are introduced in the hydrothermal reaction process. The growth orientation of metal oxide can be regulated by directional adsorption of surfactant on the surface of substrate metal. Reducing agent is introduced through hydrothermal reaction deposition to partially reduce the copper nanowires in the substrate layer to form hole copper, and nano copper particles with high specific surface area are deposited on its surface, thereby increasing the active specific surface area of ​​the copper electrode and increasing the proportion of edge and corner active sites.

[0005] Although some progress has been made in the development of nitrogen-doped carbon-supported metal single-atom electrocatalysts, the slow reaction kinetics of the proton-coupled electron transfer process involved in its reaction pathway limits its electrocatalytic CO 2 In addition, it is difficult to achieve CO reduction at a single metal atom active site. 2 Therefore, by preparing a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst, the carbon material-supported zinc single atom reduction of CO 2 While preparing CO performance, it is of great significance to further reduce the prepared CO to C2 products. Summary of the invention

[0006] The present invention aims to provide a method for preparing a nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst, and a catalyst obtained by the above preparation method and a catalyst used as a working electrode in electrocatalytic CO 2 The application in the reduction reaction to prepare ethylene shows excellent electrochemical activity and selectivity.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst comprises the following steps:

[0009] (1) dissolving a zinc salt in a solvent, adding a 2-methylimidazole solution, stirring and mixing, and centrifuging and drying to obtain a zinc-based metal organic framework precursor;

[0010] (2) dispersing the precursor prepared in step (1) in a methanol solution containing 5-amino-1,2,3-thiadiazole, stirring and mixing, and centrifugally drying to obtain a sulfur-doped zinc-based metal organic framework precursor;

[0011] (3) calcining the sulfur-doped zinc-based metal organic framework precursor prepared in step (2) to obtain the nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms;

[0012] (4) using a magnetron sputtering apparatus to sputter a high-purity copper target onto a polytetrafluoroethylene film with a pore size of 100 nm to obtain a polytetrafluoroethylene film-loaded copper nanoparticle substrate;

[0013] (5) dispersing the nitrogen / sulfur co-doped porous carbon-supported zinc single atom prepared in step (3) in an ethanol solution, and then spraying the dispersion onto the surface of a polytetrafluoroethylene membrane-supported copper nanoparticle substrate to obtain a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst.

[0014] In the present invention, 2-methylimidazole is used as an organic ligand, and a zinc-based metal organic framework compound is formed by self-assembly with divalent zinc ions. The zinc-based metal organic framework compound is then dispersed in a methanol solution containing 5-amino-1,2,3-thiadiazole, and the 2-methylimidazole ligand in the zinc-based metal organic framework compound is partially replaced with 5-amino-1,2,3-thiadiazole through a ligand exchange process to form a sulfur-containing zinc-based metal organic framework compound. Subsequently, the sulfur-doped zinc-based metal organic framework compound is carbonized through a high-temperature pyrolysis process to obtain nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms. Among them, the additionally introduced sulfur atoms serve as auxiliary sites to accelerate the dissociation of bicarbonate to provide protons, thereby accelerating CO 2 Efficient conversion on Zn-N active sites.

[0015] In step (1), the zinc salt is a soluble salt, and preferably, the zinc salt is zinc nitrate hexahydrate.

[0016] In step (1), zinc salt and 2-methylimidazole are dissolved in a solvent respectively, the reaction temperature is room temperature, the solvent is methanol, and the reaction time is 0.5 to 1 h, preferably, the reaction time is 1 h.

[0017] In step (1), the mass ratio of the zinc salt to 2-methylimidazole is 1:2.1-2.3. By changing the amount of solvent, zinc-based metal organic framework precursors of different sizes are prepared. The higher the molar concentration of zinc salt and 2-methylimidazole, the larger the size of the obtained zinc-based metal organic framework precursor.

[0018] In step (1), the mass concentration of the zinc salt after dissolution is 7.3 to 95.2 g / L, and the mass concentration of 2-methylimidazole after dissolution is 16.4 to 210.4 g / L.

[0019] Preferably, the mass concentration of the zinc salt is 7.3 g / L, and the mass concentration of 2-methylimidazole is 16.4 g / L.

[0020] The zinc-based metal organic framework precursor is dispersed in a solvent, and then a 5-amino-1,2,3-thiadiazole solution is added. The reaction temperature is room temperature and the solvent is methanol.

[0021] In step (2), the mass ratio of the zinc-based metal organic framework precursor to 5-amino-1,2,3-thiadiazole is 1:2-3, and the reaction time is 0.5-48h. The higher the concentration of 5-amino-1,2,3-thiadiazole ligands or the longer the ligand exchange time, the higher the sulfur content in the sulfur-doped zinc-based metal organic framework. When the sulfur doping amount is too low, the nitrogen / sulfur co-doped porous carbon supported zinc single atom catalytic reduction of CO 2 The performance improvement is not obvious; however, when the sulfur doping amount is too high, the activity of nitrogen / sulfur co-doped porous carbon-supported zinc single atoms in the competitive electrolysis of water and hydrogen evolution reaction is significantly improved.

[0022] Preferably, the mass ratio of the zinc-based metal organic framework precursor to 5-amino-1,2,3-thiadiazole is 1:2, and the reaction time is 48 hours to obtain the optimal sulfur doping content.

[0023] In step (3), the calcination temperature of the sulfur-doped zinc-based metal organic framework precursor is 800-1100° C., and the calcination time is 2 hours. The higher the calcination temperature, the better the conductivity of the obtained nitrogen / sulfur co-doped porous carbon supported zinc single atoms. Preferably, the calcination temperature is 1100° C. to obtain the nitrogen / sulfur co-doped porous carbon supported zinc single atoms with the best conductivity.

[0024] In step (4), the magnetron sputtering time is 0.5 to 1.5 hours. Preferably, the magnetron sputtering time is 1 hour to obtain the optimal copper nanoparticle layer thickness.

[0025] In step (5), the loading amount of zinc single atoms supported by nitrogen / sulfur co-doped porous carbon on the polytetrafluoroethylene membrane supported copper nanoparticle substrate is 0.5-1 mg cm -2 Preferably, the loading is 0.5 mg cm -2 .

[0026] The present invention also provides a nitrogen / sulfur co-doped porous carbon supported zinc single atom / metal copper tandem catalyst obtained according to the preparation method, wherein the zinc in the catalyst is coordinated and anchored with the nitrogen atom in the nitrogen / sulfur co-doped fine granular nanoporous carbon structure in the form of a single atom, and the zinc in the catalyst is anchored in the nitrogen / sulfur co-doped porous nanocarbon skeleton in the form of a single atom, and the mass percentage of the sulfur atom is 1.7-7.5wt.%. Preferably, the mass fraction of the zinc atom is 0.2wt%, the mass fraction of the sulfur atom is 4.5wt%, and the thickness of the metal copper nanoparticle layer is 300nm.

[0027] The present invention also provides a method for electrocatalyzing CO by using the nitrogen / sulfur co-doped porous carbon supported zinc single atom / metal copper tandem catalyst. 2 The catalyst exhibits excellent electrochemical activity and selectivity in the reduction reaction for preparing ethylene.

[0028] The present invention aims at reducing CO by nitrogen-doped carbon substrate supported single metal atom catalyst in the prior art. 2 The reaction kinetics are slow and it is difficult to reduce CO 2 To solve the problem of reducing C2 products, a method for preparing a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst is provided; in order to improve the carbon material-supported zinc single atom material to reduce CO 2 While preparing CO performance, the prepared CO is further reduced to C2 products. The single nitrogen / sulfur co-doped porous carbon supported zinc single atom has ultra-high CO 2 The conversion frequency to CO is close to 100% at industrial current density. Among them, the nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst has excellent CO reduction performance. 2 The catalytic performance of ethylene was -2 ) achieved a high ethylene selectivity (43%) and exhibited a high ethylene selectivity of 250 mA cm -2 The ethylene current density is 1.7 times that of pure copper nanoparticle catalyst, which significantly improves the CO 2 The conversion rate to ethylene.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention first obtains a nitrogen / sulfur co-doped porous carbon-supported zinc single atom material by using a solvent-assisted ligand exchange method combined with a high-temperature carbonization treatment method. The material has a fine granular porous nanocarbon structure with uniform particle size, a high specific surface area, uniformly dispersed single-atom zinc-nitrogen coordination active sites, and a suitable sulfur doping amount; the nitrogen / sulfur co-doped porous carbon-supported zinc single atom material is applied to the electrocatalytic CO 2 During the reduction reaction, in 0.5 M KHCO 3 In the electrolyte, it exhibits excellent electrocatalytic performance, in which the sulfur atom acts as an auxiliary site to accelerate the dissociation of bicarbonate to accelerate the transfer of protons, thereby improving the kinetics of the proton-coupled electron transfer process on the zinc-nitrogen active site, thereby accelerating CO 2 Rapid transformation at the Zn-N active site.

[0031] (2) The present invention uses magnetron sputtering and spraying methods to obtain a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst, and the thickness of the copper nanoparticle layer in the catalyst is 300nm. 2 The Zn single atom supported on nitrogen / sulfur co-doped porous carbon was reduced to CO, which increased the local concentration and residence time of CO at the interface of nitrogen / sulfur co-doped porous carbon supported Zn single atom / metallic copper. CO was further reduced to ethylene on the copper nanoparticle layer, which increased the overall CO 2 Reduction to ethylene conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a transmission electron microscopy image of nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms prepared in Example 1.

[0033] Figure 2 This is a spherical aberration correction high-angle annular dark field scanning transmission electron microscopy image of the nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms prepared in Example 1.

[0034] Figure 3 Electrocatalytic reduction of CO by zinc single atom supported on nitrogen (sulfur) co-doped porous carbon prepared in Example 1, Example 2 and Comparative Example 1 2 The yield of CO produced.

[0035] Figure 4 The nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst prepared in Example 3 is used to reduce CO 2 Properties of preparing ethylene. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment.It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.Those skilled in the art will make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention, without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.The raw materials adopted in the following specific implementation methods are all purchased from the market.

[0037] Example 1

[0038] (1) 13.14 g of 2-methylimidazole was dissolved in 400 mL of methanol by stirring, and then 400 mL of a methanol solution containing 5.80 g of zinc nitrate hexahydrate was added. The mixed solution was stirred at room temperature for 1 h, and then centrifuged and dried in a vacuum oven at 60° C. for 12 h to obtain a zinc-based metal organic framework precursor.

[0039] (2) Disperse 150 mg of the zinc-based metal organic framework precursor obtained in step (1) in 60 mL of methanol, then add 300 mg of 5-amino-1,2,3-thiadiazole, and continue stirring for 48 h. Then, centrifuge and wash with methanol solution for more than 3 times to remove residual organic ligands. Finally, dry in a vacuum drying oven at 60° C. for 12 h to obtain a sulfur-doped zinc-based metal organic framework precursor.

[0040] (3) placing the sulfur-doped zinc-based metal organic framework precursor obtained in step (2) in a tube furnace and calcining it at 1100° C. for 2 h in an argon protective gas atmosphere at a heating rate of 5° C. min -1 The collected product is nitrogen / sulfur co-doped porous carbon supporting zinc single atoms, wherein the mass fraction of sulfur is 4.5wt%.

[0041] The morphology of the obtained nitrogen / sulfur co-doped porous carbon supported zinc single atoms was observed by transmission electron microscopy. Figure 1 As shown. Figure 1 It can be seen that the material presents the morphology of accumulated fine carbon particles, and there is no accumulation of metal particles and their compounds on the surface.

[0042] Figure 2 This is a spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscopy image of nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms. It can be clearly seen that zinc is uniformly dispersed on the carbon carrier in the form of single atoms.

[0043] Example 2

[0044] According to the preparation process of Example 1, the mass of 5-amino-1,2,3-thiadiazole in step (2) was adjusted to 450 mg to obtain nitrogen / sulfur co-doped porous carbon supported zinc single atoms, wherein the mass fraction of sulfur was 7.6 wt %.

[0045] Example 3

[0046] (1) sputtering a high-purity copper target onto a polytetrafluoroethylene film with a pore size of 100 nm by magnetron sputtering for 1 h to obtain a polytetrafluoroethylene film-loaded copper nanoparticle substrate;

[0047] (2) The nitrogen / sulfur co-doped porous carbon supported zinc single atoms obtained in Example 1 were sprayed onto the surface of the polytetrafluoroethylene membrane supported copper nanoparticle substrate, with a loading amount of 0.5 mg cm -2 , and obtained nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst.

[0048] Comparative Example 1

[0049] According to the preparation process of Example 1, step (2) is not performed, and the zinc-based metal organic framework precursor obtained in step (1) is directly carbonized to obtain sulfur-free nitrogen-doped porous nanocarbon loaded with zinc single atoms.

[0050] Figure 3 Electrocatalytic reduction of CO by nitrogen / sulfur co-doped porous carbon supported by zinc single atoms prepared in Example 1 and Example 2 and by sulfur-free nitrogen-doped porous nanocarbon supported by zinc single atoms prepared in Comparative Example 1 2 Comparison of the yield of CO produced from Figure 3 It can be seen that the additional introduction of an appropriate amount of sulfur atoms has a great influence on the overall catalytic performance of nitrogen / sulfur co-doped porous carbon-supported zinc single atoms.

[0051] Comparative Example 2

[0052] The high-purity copper target was sputtered onto a polytetrafluoroethylene film with a pore size of 100 nm by magnetron sputtering for 1 h to obtain a polytetrafluoroethylene film-loaded copper nanoparticle substrate, which was directly used for the electrocatalytic reduction of CO 2 To the ethylene test.

[0053] Application example: Catalyst for electrochemical reduction of CO 2 Preparation of ethylene

[0054] The specific steps are as follows: first, 5 mg of nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms was dispersed in 500 μL of ethanol / Nafion dispersion with a volume ratio of 9:1, and then 50 μL of the dispersion was sprayed onto a 1*1 cm 2The copper nanoparticles were loaded on a polytetrafluoroethylene film substrate and placed in a liquid flow cell as a working electrode after natural drying. The electrochemical performance was measured using a three-electrode system, in which the counter electrode was nickel foam, the reference electrode was a silver / silver chloride electrode, and the electrolyte was 0.5M KHCO 3 Solution.

[0055] Cyclic voltammetry (CV) activation: Shanghai Chenhua CHI 760E electrochemical workstation was used, CV program was used, the test range was 0 to -1.2 V vs. RHE, and the scan rate was 50 mV s -1 , the electrode reaches a stable state after 40 cycles of scanning.

[0056] Linear sweep voltammetry (LSV) test: After CV activation, switch the program to the LSV program, the test range is 0 to -1.2 V vs. RHE, and the scan rate is 5 mV s -1 .

[0057] Faradaic efficiency (FE) test: The program was switched to constant current voltage-time test. During the constant current test, the product concentration was measured using gas chromatography and the FE of the product was calculated.

[0058] The results are as follows Figure 4 As shown in Figure 3, the nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst prepared in Example 3 exhibited excellent electrocatalytic CO 2 Reduction to ethylene performance, showing 250 mA cm -2 The ethylene current density is 1.7 times that of the pure copper nanoparticle catalyst prepared in Example 2, which significantly improves the CO 2 The conversion rate to ethylene.

Claims

1. A method for preparing a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst, It is characterized in that The preparation method comprises the following steps: (1) dissolving a zinc salt in methanol, adding a methanol solution containing 2-methylimidazole, stirring and mixing, and centrifuging and drying to obtain a zinc-based metal organic framework precursor; (2) dispersing the precursor prepared in step (1) in a methanol solution containing 5-amino-1,2,3-thiadiazole, stirring and mixing, so that part of the 2-methylimidazole organic linker in the zinc-based metal organic framework is replaced by 5-amino-1,2,3-thiadiazole, and obtaining a sulfur-doped zinc-based metal organic framework precursor through centrifugal drying; (3) calcining the sulfur-doped zinc-based metal organic framework precursor prepared in step (2) to obtain nitrogen / sulfur co-doped porous carbon loaded with zinc single atoms; (4) sputtering a copper target onto a polytetrafluoroethylene film to obtain a polytetrafluoroethylene film-loaded copper nanoparticle substrate; (5) dispersing the nitrogen / sulfur co-doped porous carbon-supported zinc single atom prepared in step (3) in an ethanol solution to form a dispersion, and then spraying the dispersion onto the surface of a polytetrafluoroethylene membrane-supported copper nanoparticle substrate to obtain a nitrogen / sulfur co-doped porous carbon-supported zinc single atom / metallic copper tandem catalyst; In step (2), the mass ratio of the zinc-based metal organic framework precursor to 5-amino-1,2,3-thiadiazole is 1:2-3; and the stirring time in step (2) is 0.5-48h.

2. The method for preparing nitrogen / sulfur co-doped porous carbon supported zinc single atoms according to claim 1, It is characterized in that In step (1), the mass ratio of the zinc salt to 2-methylimidazole is 1:2.1-2.

3.

3. The method for preparing nitrogen / sulfur co-doped porous carbon supported zinc single atoms according to claim 1, It is characterized in that The stirring time in step (1) is 0.5 to 1 h.

4. The method for preparing nitrogen / sulfur co-doped porous carbon supported zinc single atoms according to claim 1, It is characterized in that The calcination temperature in step (3) is 800-1100° C., and the calcination time is 1-2 hours.

5. The method for preparing the polytetrafluoroethylene film-supported copper nanoparticle substrate according to claim 1, It is characterized in that The magnetron sputtering time in step (4) is 0.5 to 1.5 hours.

6. The method for preparing the nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst according to claim 1, It is characterized in that The nitrogen / sulfur co-doped porous carbon supported zinc single atom loading on the polytetrafluoroethylene membrane supported copper nanoparticle substrate in step (5) is 0.5-1 mg·cm -2 .

7. A nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst obtained by the preparation method according to any one of claims 1 to 6, It is characterized in that In the catalyst, zinc is anchored in the nitrogen / sulfur co-doped porous nano carbon skeleton in the form of metal single atoms, the mass percentage of sulfur atoms is 1.7-7.5wt.%, and the thickness of the copper nano particle layer on the polytetrafluoroethylene membrane is 150-450nm.

8. A method for using the nitrogen / sulfur co-doped porous carbon supported zinc single atom / metallic copper tandem catalyst as a working electrode in electrocatalytic CO 2 Application in the reduction reaction to prepare ethylene.

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