Metallic copper monatomic catalyst based on molecular ligand modification and interface regulation coordination as well as preparation method and application of metallic copper monatomic catalyst

Abstract

The invention discloses a metal copper monatomic catalyst based on molecular ligand modification and interface regulation coordination and a preparation method and application thereof. The preparation method comprises the following steps: dissolving and mixing a copper salt, a surfactant and a sulfur-containing molecular ligand in water to obtain a mixed solution; dropwise adding an alkaline solution into the mixed solution to adjust the pH value, stirring the solution for aging, separating, washing and drying the solution to obtain a product, coating the product on a gas diffusion layer, and immersing the product into a hydrophobic modifier solution for soaking and modifying to obtain the gas diffusion layer. According to the invention, high efficiency is realized through a collaborative strategy of molecular ligand modification and interface regulation and control, and the selectivity and excellent stability of the catalyst for high yield of CH4 under industrial-grade current density are jointly guaranteed.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst synthesis technology, specifically to a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation, its preparation method, and its application. Background Technology

[0002] There is an urgent need to develop efficient carbon dioxide (CO2) capture and conversion technologies. Electrochemical CO2 reduction driven by renewable energy is an important pathway to achieving carbon recycling. Among the many reduction products, methane (CH4) is a highly valuable deep reduction product due to its high energy density and ease of storage and transportation. However, the electroreduction of CO2 to CH4 typically involves multiple electron-proton transfer steps, resulting in slow reaction kinetics and intense competition among reactions. Currently, while noble metal catalysts can generate CH4, they are expensive and have limited selectivity. Although copper (Cu)-based catalysts can electroreductize CO2 to CH4, their product selectivity is low, making it difficult to meet practical application requirements.

[0003] Metal single-atom catalysts, due to their highest atom utilization efficiency, uniform active centers, and tunable electronic structures, provide an ideal platform for precisely optimizing reduction pathways and improving the selectivity of target products. Among these, the regulation of the local coordination environment of the central Cu atom directly affects the adsorption strength of key reaction intermediates and the reaction pathway. In recent years, molecular ligand modification strategies have proven to be an effective means of coordinating the coordination environment. These molecular ligands, by coordinating with the central Cu atom and altering its surrounding microenvironment, can significantly modulate the electronic structure, thereby optimizing the adsorption energy for key intermediates and promoting specific reaction pathways. Therefore, molecular ligand design is a crucial step in achieving highly selective metal Cu single-atom catalysts for the electroreduction of CO2 to CH4.

[0004] CN118581494A discloses a novel bismuth-based MOF catalytic material, its preparation method, and its application. The catalyst is formed by a three-dimensional framework structure with double interpenetration. The catalyst structure is composed of several minimal asymmetric repeating structural units connected sequentially. Each minimal asymmetric repeating unit uses trivalent bismuth with a seven-coordinated capped triangular pyramidal spatial coordination configuration as a metal node. Around the metal node are three N,N'-di(5-isophthaloyl)naphthalimide ligands and one water molecule ligand. The Bi atom of the current minimal asymmetric repeating structural unit forms a Bi-O bond with the O atom of the N,N'-di(5-isophthaloyl)naphthalimide ligand in the adjacent repeating structural unit, achieving three-dimensional connection and forming a three-dimensional framework structure. This synergistic effect between the ligand and the bismuth center enables it to exhibit high activity and high selectivity in the electrocatalytic reduction of formic acid by CO2.

[0005] Besides the intrinsic activity regulation of the catalyst, the electrochemical CO2 reduction reaction occurs at the solid-liquid-gas three-phase interface. Therefore, optimizing these three interfaces, especially imparting suitable hydrophobicity to the electrode surface, is equally crucial for improving CH4 production performance. A suitable hydrophobic environment can promote the diffusion and supply of reactant gases to the active sites and accelerate the desorption of gaseous products from the active sites, avoiding deactivation of active sites and drastic local pH fluctuations caused by bubble coverage. Therefore, effective hydrophobic treatment of the catalyst electrode is an important means to overcome mass transfer limitations and improve the CO2 electroreduction performance of the catalyst at high current densities.

[0006] CN114361475A discloses a method for preparing a hydrophobic gas diffusion electrode. The core of this method lies in optimizing the microporous coating containing hydrophobic polymers and pore-forming agents, as well as the preparation steps. The aim is to improve the mass transfer efficiency of the gas diffusion electrode, reduce concentration polarization, and thus improve the CO2 conversion rate.

[0007] Despite progress in promoting CO2 methanation using metal single-atom catalysts, the structure-activity relationship between the modulation of the electronic structure of the metal center by molecular ligands, the mass transfer capability of the three-phase interface, and the selectivity for CH4 production remains unclear. Therefore, there is an urgent need to develop a comprehensive strategy that can synergistically optimize the local electronic structure of the central metal atom and the macroscopic mass transfer characteristics of the three-phase reaction interface in order to overcome the technical bottlenecks faced by existing metal single-atom catalysts in the efficient electroreduction of CO2 to CH4. Summary of the Invention

[0008] This invention addresses the shortcomings in catalytic efficiency and methane selectivity of catalysts for the electroreduction of CO2 to CH4 by providing a method for preparing a single-atom copper catalyst based on a synergistic strategy of molecular ligand modification and interface regulation. The prepared single-atom copper catalyst exhibits excellent performance in the electroreduction of CO2 to methanation at industrial-grade current densities.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation includes the following steps: Step 1: Dissolve and mix copper salt, surfactant and sulfur-containing molecular ligand in water to obtain a mixture; Step 2: Add alkaline solution dropwise to the mixture to adjust the pH, stir the solution to age it, and then separate, wash and dry the solution to obtain the catalyst; Step 3: Coat the catalyst obtained in Step 2 onto the gas diffusion layer, and immerse it in a hydrophobic modifier solution to obtain the copper single-atom catalyst.

[0010] In this invention, sulfur-containing molecular organic ligands are introduced into single-atom copper sites. Through strong interactions with the central Cu atom via coordination bonds, the local electronic structure and coordination microenvironment are modulated, optimizing the adsorption strength and configuration of the key intermediate *CO, thereby enhancing the tendency of the reaction pathway to CH4 formation. Simultaneously, a three-phase interface synergistic regulation strategy is implemented during the catalyst electrode construction stage. The active catalyst component is combined with a hydrophobic agent to form a hydrophobic catalyst layer with a specific structure, significantly enhancing the mass transfer and diffusion efficiency of CO2 gas to the active sites. This achieves a synergistic effect between molecular ligand modification and interface regulation, jointly driving the highly selective electroreduction of CO2 to produce CH4 at high current densities.

[0011] The copper salt is a soluble inorganic copper salt, including one or more of copper sulfate, copper chloride, copper nitrate, copper acetate, and their hydrates; The surfactant comprises one or more of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, or polyacrylic acid. The surfactant disperses the copper salt precursor, prevents aggregation, and assists in the formation of atomic structures, while simultaneously optimizing the local microenvironment of the copper active center in conjunction with sulfur-containing molecular ligands.

[0012] The sulfur-containing molecular ligands include one or more of cysteine, glutathione, dithiothreitol, 2-mercapto-5-n-propanepyrimidine, 2-mercaptobenzoxazole, or p-mercaptobenzoic acid. Sulfur forms strong coordination bonds with copper atoms, precisely regulating the electronic structure of the active center, optimizing the intermediate adsorption energy, and promoting its hydrogenation pathway. Cysteine ​​is preferred because its molecular structure contains a bifunctional group, which can enhance the electron density of the copper sites and stabilize the coordination structure.

[0013] The hydrophobic modifier includes one or more of fluorosilanes, polydopamine, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and (dodecyl dimethylamino)propanesulfonate. In this invention, it was unexpectedly discovered that fluorosilanes are chemically bonded to the electrode surface, ensuring the hydrophobic layer remains durable and does not detach in high current density environments compared to physical coating techniques (such as polytetrafluoroethylene and polyvinylidene fluoride), thereby maintaining efficient three-phase mass transfer and reaction stability over a long period.

[0014] The mass ratio of the copper salt to the surfactant is 1:5 to 1:10.

[0015] The sulfur-containing molecular ligand has a sulfur element to copper salt molar ratio of 1:1 to 1:5.

[0016] The alkaline solution in step 2 includes one or more of the following: potassium hydroxide solution, sodium hydroxide solution, calcium hydroxide solution, barium hydroxide solution, or ammonium hydroxide solution. The concentration of the alkaline solution is 0.1~3.0 mol / L, and the final pH value of the solution is adjusted to 4~7; In step 2, aging is carried out at room temperature with stirring for 0.5 to 5 hours.

[0017] The catalyst coating process involves dissolving the catalyst in a solution of n-propanol and Nafion perfluoropolymer, dispersing it, and then dropping the slurry onto the gas diffusion layer and drying it.

[0018] The gas diffusion layer includes one or more of carbon paper, carbon cloth, or carbon felt; The molar concentration of the hydrophobic modifier in the hydrophobic modifier solution is 1~10 mmol / L; In step 3, the soaking temperature for modification is 40~80 ℃, and the soaking time is 2~10 h.

[0019] The present invention also provides a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation obtained according to the preparation method described above.

[0020] The present invention also provides the application of the aforementioned copper single-atom catalyst as a working electrode in electrocatalytic reactions.

[0021] The electrocatalytic reaction involves the electrocatalytic reduction of CO2 to CH4 at an industrial-grade current density. The industrial-grade current density is 10 mA cm⁻¹. -2 ~800 mA cm -2 .

[0022] The high catalytic activity of the copper single-atom catalyst provided by this invention, based on a synergistic strategy of molecular ligand modification and interface regulation, mainly stems from the precise modulation of the local electronic structure of the active center of the copper single atom by ligand molecules and the synergistic enhancement of the mass transfer kinetics at the three-phase interface of the catalyst electrode. By forming strong coordination bonds between sulfur-containing organic molecular ligands and copper single atoms, the charge distribution of the central metal is optimized, enhancing its adsorption of *CO intermediates and promoting their further hydrogenation reaction, thus improving the selectivity of CH4 formation. Furthermore, the introduction of hydrophobic agents into the catalyst electrode construction creates a three-dimensional hydrophobic microporous network with high gas permeability, accelerating the diffusion and mass transfer of CO2 to the active sites, effectively alleviating concentration polarization and active site blockage under high current density. The synergistic effect of these two factors jointly achieves highly selective CH4 production from the electroreduction of CO2 at high current density.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a copper single-atom catalyst based on a synergistic strategy of molecular ligand modification and interface regulation, achieving high efficiency through this combined approach. On one hand, this strategy utilizes sulfur-containing organic molecular ligands to form strong chemical coordination bonds with copper single atoms, precisely regulating the local electronic structure of the active center, optimizing charge distribution, and promoting its hydrogenation reaction. On the other hand, introducing a hydrophobic agent into the catalyst electrode constructs a highly gas-permeable three-dimensional hydrophobic microporous network, significantly accelerating diffusion mass transfer near the active site and effectively mitigating concentration polarization and active site blockage under high current densities. The synergistic effect of these two approaches ensures high CH4 production selectivity and excellent stability of the catalyst at industrial-grade current densities. Attached Figure Description

[0024] Figure 1 Scanning electron microscope image of the copper single-atom catalyst prepared in Example 1 based on the synergistic strategy of molecular ligand modification and interface regulation.

[0025] Figure 2 Aberration-corrected electron microscopy image of the copper single-atom catalyst prepared in Example 1 based on a synergistic strategy of molecular ligand modification and interface regulation.

[0026] Figure 3 The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested in an alkaline electrolyte at pH 12 at 100–600 mA cm⁻¹. -2 Figure showing the performance test results of CO2 electroreduction within the current density range.

[0027] Figure 4 The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested in a neutral electrolyte at pH 7 at 100–600 mA cm⁻¹. -2 Figure showing the performance test results of CO2 electroreduction within the current density range.

[0028] Figure 5 The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested in an acidic electrolyte at pH 2 at 100–600 mA cm⁻¹. -2 Figure showing the performance test results of CO2 electroreduction within the current density range.

[0029] Figure 6 The single-atom copper catalysts prepared in Examples 1-6 and Comparative Examples 1-5 were tested at 400 mA cm⁻¹. -2 Comparison of CO2 electroreduction performance test results under current density.

[0030] Figure 7The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested at 400 mA cm⁻¹. -2 Figure showing the stability test results under current density. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0032] All raw materials used in the following specific implementation methods were purchased from the market.

[0033] Example 1 Dissolve 100 mg of anhydrous copper sulfate in 10 mL of water and stir to obtain a homogeneous solution. Then add 1.2 g of polyvinylpyrrolidone powder and 0.3 g of cysteine ​​powder to the solution and stir thoroughly to dissolve to form a mixture. Add 1.0 M NaOH aqueous solution dropwise to the mixture obtained in step (1) until the pH value of the solution is adjusted to 5, and continue stirring for aging for 1 h. Then, centrifuge the product, wash and dry it to obtain catalyst powder. 10 mg of the catalyst powder obtained in step (2) was suspended in 1 mL of n-propanol and 20 μL of Nafion perfluorinated resin solution (5 wt.%) and ultrasonically dispersed. Then, 0.2 mL of catalyst slurry was slowly added dropwise and cast onto carbon paper to achieve a catalyst loading of approximately 1.0 mg / cm³. -2 Before the experiment, the gas diffusion electrode was completely dried to obtain the gas diffusion electrode. Then, the electrode was placed in a 6 mmol / L fluorosilane solution and immersed at 60 °C for 6 h for self-growth treatment to achieve interface control, thus obtaining a fluorosilane-modified copper single-atom catalyst.

[0034] The macroscopic morphology of the copper single-atom catalyst prepared above based on the synergistic strategy of molecular ligand modification and interface regulation was observed by scanning electron microscopy, and the results are as follows: Figure 1 As shown, its morphology is a rough-surfaced aggregate. The atomic structure distribution of the copper single-atom catalyst based on a synergistic strategy of molecular ligand modification and interface regulation was observed using aberration-sensor transmission electron microscopy, and the results are as follows: Figure 2 As shown, copper atoms exist in an atomically dispersed structure, indicating the successful preparation of a single-atom copper catalyst.

[0035] Example 2 Following the preparation process of Example 1, the addition of 1.2 g of polyvinylpyrrolidone powder in step (1) was replaced with the addition of 1.2 g of polyethylene glycol, while the other steps remained unchanged, to obtain a single-atom copper catalyst based on a synergistic strategy of molecular ligand modification and interface regulation.

[0036] Example 3 Following the preparation process of Example 1, the 0.3 g of cysteine ​​powder added in step (1) was replaced with an equal molar amount of glutathione, while the other steps remained unchanged, to obtain a single-atom copper catalyst based on a synergistic strategy of molecular ligand modification and interface regulation.

[0037] Example 4 According to the preparation process of Example 1, 0.5 M NaOH aqueous solution was added dropwise in step (2) until the pH value of the solution was adjusted to about 7. The solution was then continuously stirred for aging for 0.5 h. The remaining steps remained unchanged, and a single-atom copper catalyst based on the synergistic strategy of molecular ligand modification and interface regulation was obtained.

[0038] Example 5 According to the preparation process of Example 1, in step (3), the self-growth treatment of the electrode in a 6 mmol / L fluorosilane solution was replaced by the self-growth treatment of the electrode in a 6 mmol / L polydopamine solution, while the other steps remained unchanged, and a single-atom copper catalyst based on the synergistic strategy of molecular ligand modification and interface regulation was obtained.

[0039] Example 6 According to the preparation process of Example 1, in step (3), the electrode was placed in a 10 mmol / L fluorosilane solution and immersed at 80 °C for 3 h for self-growth treatment to achieve interface regulation. The remaining steps remained unchanged, and a single-atom copper catalyst based on the synergistic strategy of molecular ligand modification and interface regulation was obtained.

[0040] Comparative Example 1 Following the preparation process of Example 1, without performing the step (3) of placing the electrode in the hydrophobic modifier for self-growth treatment and interface regulation, the catalyst powder obtained in step (2) is coated on carbon paper to prepare a gas diffusion electrode, thus obtaining a single-atom copper catalyst based on molecular ligand modification but without interface regulation.

[0041] Comparative Example 2 According to the preparation process of Example 1, in step (1), the sulfur-containing molecular ligand cysteine ​​powder was replaced with an equal molar amount of alanine to obtain a copper single-atom catalyst with a synergistic strategy of alanine molecular ligand modification and interface regulation.

[0042] Comparative Example 3 According to the preparation process of Example 1, in step (1), the sulfur-containing molecular ligand cysteine ​​powder was replaced with an equal molar amount of glutamic acid to obtain a copper single-atom catalyst with a synergistic strategy of glutamic acid molecular ligand modification and interface regulation.

[0043] Comparative Example 4 According to the preparation process of Example 1, in step (3), 10 mg of catalyst powder obtained in step (2) and 1 mg of polytetrafluoroethylene powder are suspended together in 1 mL of n-propanol and 20 μL of Nafion perfluorinated resin solution (5 wt.%) and ultrasonically dispersed to prepare a gas diffusion electrode. The step of placing the electrode in the hydrophobic modifier for self-growth treatment interface regulation in step (3) is not performed thereafter, so as to obtain a copper single-atom catalyst with a synergistic strategy of molecular ligand modification and interface regulation.

[0044] Comparative Example 5 According to the preparation process of Example 1, in step (3), 10 mg of catalyst powder obtained in step (2) and 1 mg of polyvinylidene fluoride powder are suspended together in 1 mL of n-propanol and 20 μL of Nafion perfluorinated resin solution (5 wt.%) and ultrasonically dispersed to prepare a gas diffusion electrode. The step of placing the electrode in the hydrophobic modifier for self-growth treatment interface control in step (3) is not performed subsequently. The obtained catalyst electrode is directly subjected to subsequent tests.

[0045] Application example: Electroreduction of CO2 methanation reaction at industrial-grade current density The electrode material prepared above was used as the working electrode in a three-electrode flow electrolyzer, with an anion exchange membrane separating the flow chambers on both sides of the electrolyzer. The counter electrode and reference electrode were nickel foam and silver / silver chloride electrodes, respectively.

[0046] Cyclic voltammetry (CV) activation: A Shanghai Chenhua CHI 760E electrochemical workstation was used with a CV program. The test range was -0.5 to -1.9 V vs. RHE, and the scan rate was 50 mV s. -1 After 30 cyclic scans, the electrode reaches a stable state.

[0047] Faraday efficiency (FE) test: The program is switched to constant current-time test. During the constant current test, the concentration of gaseous products is quantitatively determined online using gas chromatography (GC, Fuli 9790II).

[0048] The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of ligand modification and interface regulation, was prepared in a 1.0 M KOH alkaline electrolyte at 100–600 mA cm⁻¹. -2 It exhibits excellent performance in the electroreduction of CO2 methanation within the current density range, as shown in the results. Figure 3As shown in Table 1, at 400 mA cm -2 At current densities, the Faraday efficiency of the CH4 product reaches as high as 73.4% (200–600 mA cm⁻¹). -2 The selectivity of CH4 products remains above 54% within the current density range.

[0049] Table 1. Catalytic results of the catalyst prepared in Example 1 at different current densities in alkaline electrolyte.

[0050] The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested in a 1.0 M KHCO3 neutral electrolyte at 100–600 mA cm⁻¹. -2 It exhibits excellent electroreduction CO2 methanation performance within the current density range, as shown in the results. Figure 4 As shown in Table 2, at 300 mA cm -2 At current densities, the product CH4 exhibits a Faraday efficiency of 70.1% in the range of 200–600 mA cm⁻¹. -2 Within the current density range, the selectivity of the product CH4 remains above 51%.

[0051] Table 2 Catalytic results of the catalyst prepared in Example 1 at different current densities in neutral electrolyte.

[0052] The copper single-atom catalyst prepared in Example 1, based on a synergistic strategy of molecular ligand modification and interface regulation, was tested in an acidic electrolyte of 3.0 M KCl and 0.005 M H₂SO₄ at 100–600 mA cm⁻¹. -2 It exhibits excellent electroreduction CO2 methanation performance within the current density range, as shown in the results. Figure 5 As shown in Table 3, at 400 mA cm -2 At current densities, the Faraday efficiency of the product CH4 reaches 66.2% in the range of 200–600 mA cm⁻¹. -2 Within the current density range, the selectivity of the product CH4 remains above 47%.

[0053] Table 3 Catalytic results of the catalyst prepared in Example 1 at different current densities in acidic electrolyte.

[0054] The copper single-atom catalysts based on the synergistic strategy of molecular ligand modification and interface regulation prepared in Examples 1-6 and Comparative Examples 1-5, and the copper single-atom catalyst based on molecular ligand modification, were subjected to a test at 400 mA cm⁻¹. -2The performance of the electrolyte in 1.0 M KOH at different current densities was compared, and the results are as follows: Figure 6 As shown in Table 4, the effects of Comparative Examples 2 and 3 are significantly reduced because the ligands are sulfur-free. Comparative Example 1 also shows poorer results due to the lack of subsequent chemical hydrophobic modification. Comparative Examples 4 and 5 used polyvinylidene fluoride for physical hydrophobic modification, which improved upon Comparative Example 1, but still did not perform as well as the chemical modification method in Example 1.

[0055] Table 4. Catalytic performance of the catalysts prepared in the examples and comparative examples in alkaline electrolytes.

[0056] The stability of the catalyst electrode material prepared in Example 1 was tested in a flow electrolyzer, such as... Figure 7 As shown, at 400 mA cm -2 At a current density of [value missing], it can operate stably for 12 hours, and the Faraday efficiency of the product CH4 remains above 70%.

Claims

1. A method for preparing a single-atom catalyst of metallic copper based on the synergistic effect of molecular ligand modification and interface regulation, characterized in that, Including the following steps: Step 1: Dissolve and mix copper salt, surfactant and sulfur-containing molecular ligand in water to obtain a mixture; Step 2: Add alkaline solution dropwise to the mixture to adjust the pH, stir the solution to age it, and then separate, wash and dry the solution to obtain the catalyst; Step 3: Coat the catalyst obtained in Step 2 onto the gas diffusion layer, and immerse it in a hydrophobic modifier solution to obtain the copper single-atom catalyst.

2. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The copper salt is a soluble inorganic copper salt, including one or more of copper sulfate, copper chloride, copper nitrate, copper acetate, and their hydrates; And / or, the surfactant includes one or more of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, or polyacrylic acid.

3. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The sulfur-containing molecular ligands include one or more of cysteine, glutathione, dithiothreitol, 2-mercapto-5-n-propanepyrimidine, 2-mercaptobenzoxazole, or p-mercaptobenzoic acid.

4. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The hydrophobic modifier includes one or more of fluorosilane, polydopamine, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and (dodecyl dimethylamino)propanesulfonate.

5. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The mass ratio of the copper salt to the surfactant is 1:5 to 1:10; And / or, the molar ratio of sulfur to copper salt in the sulfur-containing molecular ligand is 1:1 to 1:

5.

6. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The alkaline solution in step 2 includes one or more of the following: potassium hydroxide solution, sodium hydroxide solution, calcium hydroxide solution, barium hydroxide solution, or ammonium hydroxide solution. And / or, the concentration of the alkaline solution is 0.1~3.0 mol / L, and the final pH value of the solution is adjusted to 4~7; And / or, in step 2, aging is carried out at room temperature with stirring for 0.5 to 5 hours.

7. The method for preparing a single-atom copper catalyst based on the synergistic effect of molecular ligand modification and interface regulation according to claim 1, characterized in that, The gas diffusion layer includes one or more of carbon paper, carbon cloth, or carbon felt; And / or, the molar concentration of the hydrophobic modifier in the hydrophobic modifier solution is 1~10 mmol / L; And / or, in step 3, the soaking temperature for modification is 40~80 ℃, and the soaking time is 2~10 h.

8. The copper single-atom catalyst based on the synergistic effect of molecular ligand modification and interface regulation obtained by the preparation method according to any one of claims 1-7.

9. The application of the copper single-atom catalyst according to claim 8 as a working electrode in electrocatalytic reactions.

10. The application according to claim 9, characterized in that, The electrocatalytic reaction is the electrocatalytic reduction of CO2 to CH4 at industrial-grade current density.

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