Preparation method and application of a hydrophobic MIL-160 / Cu2O heterostructure catalyst

Abstract

This invention discloses a method for preparing and applying a hydrophobic MIL-160 / Cu2O heterostructure catalyst. The catalyst uses MIL-160 as a substrate, and the oxygen-containing functional groups on its surface anchor Cu through electrostatic interactions. 2+ Ultimately, a MIL-160 / Cu2O heterostructure was constructed. This heterostructure can repel water molecules and enrich carbon dioxide at the heterojunction interface, effectively suppressing the competitive hydrogen evolution reaction. Simultaneously, the strong electronic interactions at the heterojunction interface lower the energy barrier of the key C-C coupling step and stabilize the reaction intermediate. This catalyst is particularly suitable for the electrocatalytic reduction of carbon dioxide to ethylene and other high-value-added multi-carbon products, exhibiting high selectivity, high activity, and long-term operational stability.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying an electrocatalytic material, and more particularly to a method for preparing and applying a hydrophobic MIL-160 / Cu2O heterostructure catalyst. Background Technology

[0002] Among numerous carbon capture and utilization technologies, electrocatalytic carbon dioxide reduction reaction (CO2RR) is considered one of the key pathways to achieve a sustainable carbon cycle. Among the various known electrocatalysts, copper (Cu)-based catalysts, due to their moderate adsorption energy for *CO intermediates and their ability to promote CC coupling reactions, are among the few metallic materials capable of efficiently converting CO2 into multi-carbon products, and have attracted considerable attention from researchers.

[0003] However, copper-based catalysts still face several key challenges in practical applications, and researchers have developed various modification strategies. Nanomorphological manipulation optimizes the distribution of active sites by exposing specific crystal faces, but it often struggles to effectively control the reaction microenvironment. Elemental doping can adjust the electronic structure of the catalyst, but dopants are easily lost during the reaction, leading to insufficient long-term stability. Alloying strategies can optimize intermediate adsorption energies, but metal leaching remains a significant challenge. Surface modification can enhance the adsorption of key intermediates, but it may hinder reactant mass transfer and increase preparation complexity. Most of these methods focus on optimizing the intrinsic activity of the catalyst, neglecting the crucial role of reactant mass transfer and intermediate stability at the gas-liquid-solid three-phase interface.

[0004] MOFs (Metal-Organic Facility Materials) exhibit unique advantages in constructing catalytic microenvironments due to their high specific surface area, tunable pore structure, and ease of functionalization. However, existing MOF-based catalysts still suffer from a series of inherent defects. First, most MOFs exhibit poor stability in aqueous or humid environments, with their metal-ligand coordination bonds prone to hydrolysis and breakage, leading to framework collapse and loss of active centers, severely limiting their practical application in aqueous or liquid-phase reaction systems. Second, regarding microenvironment control, traditional MOF catalysts often lack effective hydrophobic design; hydrophilic channels easily adsorb water molecules, occupying active sites, hindering substrate access, and inducing undesirable side reactions. Simultaneously, most MOF catalysts struggle to construct ideal gas-liquid-solid three-phase interfaces, hindering mass transfer of gaseous reactants (such as oxygen and carbon dioxide) in the liquid environment, preventing them from efficiently reaching the solid catalyst surface to participate in the reaction, thus limiting the efficiency of heterogeneous catalytic processes involving gas participation. Furthermore, MOFs themselves typically have poor electrical conductivity, resulting in low internal charge transport efficiency when used as electrocatalysts or photocatalysts. This makes it difficult to effectively transfer electrons to the surface active sites, thus limiting the catalytic reaction rate. Moreover, the active centers of many MOF materials are often encased within pores, requiring substrate molecules to overcome diffusion resistance to reach the active sites, leading to limited mass transfer, especially under conditions of high current density or high substrate concentration. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for preparing a hydrophobic MIL-160 / Cu2O heterostructure catalyst with high selectivity, high stability and high current density. The second purpose of this invention is to provide the application of the hydrophobic MIL-160 / Cu2O heterostructure catalyst obtained by the above method.

[0006] Technical solution: The preparation method of the hydrophobic MIL-160 / Cu2O heterostructure catalyst of the present invention includes the following steps:

[0007] (1) MIL-160 metal-organic framework was prepared by hydrothermal method;

[0008] (2) Disperse the MIL-160 metal-organic framework in a solvent, add polyvinylpyrrolidone and copper salt, and stir until completely dissolved;

[0009] (3) Add an alkaline solution to the solution obtained in step (2) and stir thoroughly to obtain a blue-green Cu(OH)2 suspension, which then turns dark brown;

[0010] (4) Add a reducing agent to the Cu(OH)2 suspension obtained in step (3), heat and stir, centrifuge the product after reaction, wash and dry it to obtain the hydrophobic MIL-160 / Cu2O heterostructure catalyst.

[0011] The molar ratio of MIL-160 to Cu2O in the MIL-160 / Cu2O heterostructure catalyst is 3:1 to 1:3.

[0012] The mass ratio of the MIL-160 metal-organic framework to the copper salt is 2.6:1 to 1:0.15; the mass ratio of the polyvinylpyrrolidone to the copper salt is 0 to 9.6:1. Preferably, the amount of polyvinylpyrrolidone added is 1.3g to 3.6g.

[0013] The concentration of the copper salt solution obtained in step (2) is 0.5-5 mM; the concentration of the alkaline solution added in step (3) is 0.1-0.5 M; and the concentration of the reducing agent added in step (4) is 0.05-0.1 M.

[0014] The copper salt is at least one of copper nitrate, copper chloride, or copper sulfate; the reducing agent is glucose or ascorbic acid solution.

[0015] In step (2), the solvent is deionized water or ethanol.

[0016] In step (3), an alkaline solution is added slowly and evenly at a rate of 4-6 ml / min using an injection pump at room temperature to adjust the pH of the reaction system to 9.0-11.0, and the stirring speed is 500-800 rpm.

[0017] In step (4), the reaction temperature is 50-80℃ and the reaction time is 2-4 hours.

[0018] In step (4), the reducing agent is added slowly and evenly using a syringe pump at a rate of 1-3 ml / min, and the stirring speed is 400-600 rpm. The mixture is stirred at a temperature of 40-60℃ for 4 hours.

[0019] The application of the above-mentioned hydrophobic MIL-160 / Cu2O heterostructure catalyst in the electrocatalytic carbon dioxide reduction reaction.

[0020] The catalyst is used to electrochemically reduce carbon dioxide to multi-carbon products, including at least one of ethylene and ethanol.

[0021] Its preferred application is in the electrocatalytic production of ethylene from carbon dioxide.

[0022] The catalyst is used in electrode form, and includes the following steps:

[0023] (1) Disperse the catalyst in ethanol and add Nafion solution to prepare catalyst ink;

[0024] (2) The catalyst ink is drop-coated onto the surface of the gas diffusion electrode and dried to obtain the catalyst electrode;

[0025] (3) Using the catalytic electrode as the working electrode, the platinum mesh as the counter electrode, and the silver-silver chloride electrode as the reference electrode, an electrocatalytic carbon dioxide reduction reaction is carried out in a flow cell.

[0026] The electrolyte is a 0.1 M KHCO3 solution, the carbon dioxide gas flow rate is 10-30 mL / min, the reaction potential is -0.8 V to -1.5 V (vs. RHE), and the current density is -100 mA cm⁻¹. -2 to -300 mA cm -2 .

[0027] At -1.4 V (vs. RHE), C 2+ The product Faraday efficiency is not less than 82%, and the ethylene Faraday efficiency is not less than 68%.

[0028] The application uses an electrocatalytic carbon dioxide reduction system, which includes a catalytic electrode made from the catalyst described above, an electrolytic cell, a gas supply device, and an electrochemical workstation. The electrolytic cell is a flow cell, and an anion exchange membrane is provided between the cathode chamber and the anode chamber.

[0029] The system also includes an online gas chromatograph and / or nuclear magnetic resonance spectrometer for real-time monitoring of reaction products.

[0030] This invention proposes the construction of a MIL-160 / Cu2O heterostructure catalyst. MIL-160, as an aluminum-based carboxylic acid MOF, exhibits excellent hydrothermal stability. Its unique oxygen-containing functional groups provide a suitable hydrophobic microenvironment on the pore surface, effectively repelling water molecules and enriching the substrate. Simultaneously, by combining Cu2O nanoparticles with MIL-160, a rich three-phase interface can be constructed, promoting efficient mass transfer between the gas, liquid, and solid catalysts. Furthermore, the heterojunction effect formed at the interface significantly enhances charge separation and migration efficiency, thereby overcoming the shortcomings of single MOF components in terms of stability, hydrophobic regulation, three-phase interface construction, and charge transport.

[0031] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0032] (1) Extremely high C 2+Product Selectivity and Activity: The MIL-160 / Cu2O heterointerface constructed in this invention effectively suppresses the competitive hydrogen evolution reaction (HER) by enriching CO2 and repelling water molecules through hydrophobic MIL-160. Simultaneously, the strong electron interactions at the interface optimize the d-band center of the Cu sites, stabilizing key intermediates such as *OCCO and significantly reducing the energy barrier of CC coupling. In 0.1 M KHCO3 electrolyte, at a potential of -1.4 V (vs. RHE), C 2+ The overall Faradaic efficiency of the product is as high as 85.2%, with a selectivity of 68.8% for ethylene and a partial current density as high as 146.2 mA cm⁻¹. -2 .

[0033] (2) Excellent long-term operational stability: The MIL-160 framework not only provides a hydrophobic microenvironment, but also effectively stabilizes Cu during electrochemical reduction through strong interfacial interactions with Cu2O. + Species that prevent excessive reduction, aggregation, or structural collapse of the catalyst. At 350 mA cm⁻¹ -2 At high current densities, this catalyst can operate stably continuously for over 150 hours. 2+ The product's Faraday efficiency remained above 82%, far exceeding that of the pure Cu2O catalyst after 8 hours.

[0034] (3) Clear mechanism and designability: By combining in-situ spectroscopy, such as ATR-FTIR, and theoretical calculations, such as DFT and MD simulation, this invention clearly reveals the dual synergistic mechanism of "electronic structure regulation" and "three-phase microenvironment regulation" at the heterogeneous interface, providing a clear guiding idea and an scalable material platform for the rational design of the next generation of high-performance CO2RR catalysts.

[0035] (4) The preparation method is simple and has industrialization potential: The preparation method of this invention is based on conventional hydrothermal and electrostatic attraction processes. The raw materials are readily available, the conditions are mild, the controllability is strong, and it is easy to scale up production. The high current density and excellent stability exhibited by the catalyst in the flow cell indicate its potential for integration into industrial electrolysis devices. Attached Figure Description

[0036] Figure 1 These are scanning electron microscope images of MIL-160, the MIL-160 / Cu2O heterostructure in Example 1 of the present invention, and the Cu2O cube in Comparative Example 1.

[0037] Figure 2 This is a comparison of the Faraday efficiency of the Cu2O cube of Comparative Example 1 and the MIL-160 / Cu2O heterostructure of Example 1 in the electrocatalytic reduction of CO2 to C2H4 at a current density of -200 mA / cm².

[0038] Figure 3 This is a comparison of the Faraday efficiency of five electrodes with different Al / Cu molar ratios in Comparative Example 5 for the electrocatalytic reduction of CO2 to C2H4 at a current density of -200 mA / cm².

[0039] Figure 4 This is a comparison chart of the long-term stability of two catalysts, MIL-160 in Example 1 and Cu2O cubic catalyst in Comparative Example 1, at -1.4V vs. RHE potential.

[0040] Figure 5 This is a comparison chart of the Faraday efficiency of the electrocatalytic reduction of CO2 to C2H4 of the MIL-160 / Cu2O heterostructure obtained by different amounts of polyvinylpyrrolidone (PVP) added in Example 3.

[0041] Figure 6 This is a comparison chart of the Faraday efficiency of the electrocatalytic reduction of CO2 to C2H4 by the MIL-160 / Cu2O heterostructure obtained with different ascorbic acid solution concentrations in Example 4. Detailed Implementation

[0042] The present invention will now be described in further detail.

[0043] Example 1

[0044] (1) Preparation of MIL-160

[0045] Weigh 0.18 g of AlCl3·6H2O, 0.232 g of 2,5-furandicarboxylic acid (FDCA), and 0.185 g of sodium formate (HCOONa), and dissolve them in 30 mL of deionized water. Stir for 30 minutes until homogeneous. Transfer the mixture to a 50 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), place it in an oven, and perform a hydrothermal reaction at 150 °C for 4 hours. After the reaction, allow it to cool naturally to room temperature. Centrifuge the resulting white solid product, wash it three times with acetone, and then dry it in a vacuum drying oven at 60 °C for 12 hours to obtain hydrophobic MIL-160 powder. The water contact angle was measured to be 137.7°.

[0046] (2) Preparation of MIL-160 / Cu2O heterostructure composite material

[0047] Weigh 150 mg of the MIL-160 powder prepared in step (1) and disperse it in 200 mL of deionized water. Sonicate for 30 minutes to form a uniform suspension. Add 342 mg of CuCl2·2H2O and 3.3 g of PVP to the suspension and stir to dissolve. While stirring continuously, add 10 mL of 2 M NaOH solution dropwise. At this point, a light blue flocculent precipitate appears in the solution. Heat the reaction system to 60℃, and then use a syringe pump to add 20 mL of 0.6 M ascorbic acid aqueous solution at a rate of 2 mL / min. The solution color gradually changes from blue to yellow, and finally to orange-yellow. Continue stirring at this temperature for 4 hours. After the reaction is complete, centrifuge, wash, and dry to obtain the MIL-160 / Cu2O composite material, labeled as MIL-160 / Cu2O; wherein the molar ratio of MIL-160 to Cu2O is 1:1. The water contact angle of this composite material is 101.4°.

[0048] Comparative Example 1

[0049] Preparation of Cu2O cubes:

[0050] 1 mmol CuCl₂·2H₂O and 1.8 g PVP (Mw = 13000) were dissolved in 100 mL of deionized water and magnetically stirred until completely dissolved. While stirring continuously, 10 mL of 2 M NaOH solution was added dropwise, resulting in a light blue flocculent precipitate. The reaction system was heated to 60 °C, and then 20 mL of 0.6 M ascorbic acid aqueous solution was added dropwise at a rate of 2 mL / min using a syringe pump. The solution color gradually changed from blue to yellow, and finally to orange-yellow. Stirring was continued at this temperature for 4 hours. After the reaction was complete, the mixture was allowed to cool naturally, and the orange-red solid was collected by centrifugation. The solid was washed three times alternately with deionized water and anhydrous ethanol, and finally dried under vacuum at 60 °C for 12 hours to obtain Cu₂O cubic powder with a water contact angle of 31.6°.

[0051] Example 2

[0052] Preparation of catalytic electrode:

[0053] Take 3 mg each of pure Cu₂O prepared in Comparative Example 1 and Example 1, and MIL-160 / Cu₂O catalyst powder in a 1:1 molar ratio, and mix them with 500 μL of anhydrous ethanol and 30 μL of 5 wt% Nafion solution, respectively. Sonicate the mixtures for at least 30 minutes to form a uniform catalyst ink. Use a micropipette to uniformly coat the ink onto pre-treated 1 cm × 1 cm YLS-30T carbon paper, controlling the catalyst loading to approximately 1 mg / cm². 2 The coated electrode was allowed to air dry overnight at room temperature to obtain the catalytic electrode.

[0054] The following tests were performed on the catalytic electrode of Example 2:

[0055] 1. Electrocatalytic CO2 reduction performance test:

[0056] Electrochemical tests were performed in a self-assembled flow cell. The electrode prepared in Example 2 was used as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. All potentials were converted to reversible hydrogen electrode (RHE). The anode and cathode chambers were separated by an anion exchange membrane; in this example, the anion exchange membrane used was Fumasep FAA-3-50. The electrolyte was 30 mL of 0.1 MKHCO3 solution, circulated using a peristaltic pump at a rate of 50 rpm. High-purity CO2 gas was continuously introduced into the anode chamber at a flow rate of 30 sccm. Potentiostatic measurements were performed using an electrochemical workstation (CHI760E), with a potential range of -0.8 V to -1.5 V (vs. RHE). Gas phase products were analyzed by automated injection every 25 minutes using an online gas chromatograph (GC-2014C, Shimadzu), and liquid phase products were analyzed by ¹H NMR after the reaction. Test results: The MIL-160 / Cu2O (molar ratio 1:1) composite exhibits optimal performance at -1.4 V (vs. RHE). 2+ The overall Faradaic efficiency of the products was 85.2%, with ethylene (C2H4) exhibiting a Faradaic efficiency of 68.8% and a partial current density of 146.2 mA cm⁻¹. -2 In contrast, pure Cu₂O cubes at the same potential... 2+ The total FE content of the product is only about 49.5%, and the FE content of C2H4 is about 35.4%.

[0057] 2. Long-term stability testing:

[0058] In the aforementioned flow cell system, a 1:1 MIL-160 / Cu2O composite electrode was used as the working electrode. Continuous electrolysis tests were conducted at a constant potential of -1.4 V (vs. RHE), and the total current density stabilized at approximately 350 mA cm⁻¹. -2 The product was continuously monitored via online GC. Results showed that after 150 hours of continuous operation, the catalyst... 2+ The product's Faraday efficiency remained above 82%, and the electrode structure remained intact. Meanwhile, the pure Cu₂O electrode at 100 mA cm⁻¹... -2 After running for 8 hours, the performance showed a significant decline.

[0059] Example 3

[0060] Performance comparison of different amounts of polyvinylpyrrolidone added:

[0061] Following the method in Example 1, different amounts of polyvinylpyrrolidone were added during the preparation of the MIL-160 / Cu2O heterostructure composite material, namely 0g, 1.6g, and 3.3g of polyvinylpyrrolidone, to prepare the MIL-160 / Cu2O heterostructure composite material, and electrodes were then fabricated for testing.

[0062] Example 4

[0063] Comparison of performance when adding ascorbic acid solutions of different concentrations:

[0064] Following the method in Example 1, ascorbic acid solutions of different concentrations were added during the preparation of the MIL-160 / Cu2O heterostructure composite material. The concentrations added were 0.4M, 0.6M, and 0.8M, respectively, to prepare the MIL-160 / Cu2O heterostructure composite material, and electrodes were then fabricated for testing.

[0065] Example 5

[0066] Performance comparison of different MIL-160 / Cu2O molar ratios:

[0067] Following the method in Example 1, composite materials with MIL-160 and Cu2O molar ratios of 3:1, 2:1, 1:1, 1:2, and 1:3 were prepared and fabricated into electrodes for testing. The results showed that when the molar ratio was 1:1, the catalyst achieved the optimal balance between hydrophobicity and hydrophilicity, i.e., the optimal balance between CO2 enrichment and proton transfer, forming the most ideal gas-liquid-solid three-phase interface, thus exhibiting the highest C2H4 selectivity. Other ratios either hindered mass transfer due to excessive hydrophobicity or intensified HER competition due to excessive hydrophilicity, resulting in decreased performance.

[0068] Comparative Example 2

[0069] Preparation and testing of physically mixed MIL-160 and Cu2O electrodes

[0070] To verify the importance of in-situ construction of heterogeneous interfaces, a physical mixing method was used in this comparative example. MIL-160 prepared in Example 1 and Cu2O powder prepared in Comparative Example 1 were physically ground and mixed at a molar ratio of 1:1. 2 mg of this mixed powder was used to prepare an electrode using the same method as in Example 2, and the results were tested according to the method in Example 2. The results showed that, under the same test conditions, the C2 of this physically mixed electrode was significantly higher than that of the standard electrode. 2+ The maximum Faraday efficiency of the product was only 46.7%, which is much lower than the 85.2% of the MIL-160 / Cu2O composite material synthesized in situ in Example 1. This confirms that the in-situ construction of a tight heterostructure is crucial for achieving strong electronic coupling and excellent catalytic performance.

[0071] Figure 1Figure 'a' shows a spherical MIL-160 metal-organic framework material with an average particle size of approximately 5 μm. Figure 1 b in the figure shows cubic Cu2O with an average particle size of approximately 300 nm. Figure 1 c in the figure shows the MIL-160 / Cu2O composite material.

[0072] Figure 2 The differences in electrochemical performance between Comparative Example 1 and Example 1 were compared. The test conditions were set at a current density of 200 mA / cm². 2 The reaction was continued for 30 minutes, and the ordinate represents the ethylene Faradaic efficiency (%), reflecting the Faradaic efficiency of the target product. The results showed that the Faradaic efficiency of Comparative Example 1 was approximately 35.4%, while the Faradaic efficiency of Example 1 was significantly improved to approximately 68.8%. Under the same high current density and reaction time, the significant increase in the Faradaic efficiency of Example 1 indicates that, as a heterostructure catalyst, it optimized the reaction pathway through interfacial synergistic effects, effectively suppressing side reactions such as hydrogen evolution, thus exhibiting superior product selectivity and catalytic activity under harsh electrolysis conditions.

[0073] Figure 3 This study investigated the effect of the aluminum-copper molar ratio on the ethylene Faradaic efficiency. The data showed that as the aluminum ratio decreased, from an Al / Cu ratio of 3:1 to 1:3, the ethylene Faradaic efficiency exhibited a single-peak trend, first increasing and then decreasing. At an Al / Cu ratio of 1:1, the ethylene Faradaic efficiency reached its peak of 68.8%; however, when the ratio was too high (e.g., 3:1) or too low (e.g., 1:3), the ethylene Faradaic efficiency decreased to 39.5% and 48.6%, respectively. This indicates that there is an optimal stoichiometric ratio of aluminum to copper, approximately 1:1, at which point they form a synergistic effect, most favorable for electrocatalysis. Deviating from this optimal ratio, whether in excess of aluminum or copper, may lead to a reduction in the active phase or the formation of inactive species, thereby decreasing the reaction efficiency.

[0074] Figure 4 The long-term stability performance of Comparative Example 1 and Example 1 was compared. Data showed that Comparative Example 1 maintained stability for only 8 hours, while Example 1 maintained stability for up to 150 hours, with the latter's lifespan significantly exceeding that of the former. This substantial difference fully demonstrates the significant advantage in durability of the heterostructure catalyst represented by Example 1. This extreme difference in stability is attributed to the fact that the construction of the heterostructure effectively inhibited the aggregation, dissolution, or poisoning of the active components, thus maintaining structural integrity and catalytic activity during a continuous reaction lasting up to 150 hours.

[0075] Figure 5The results showed that in Example 3, increasing the PVP addition from 0 g to 3.3 g increased the ethylene Faradaic efficiency of the MIL-160 / Cu2O heterostructure catalyst from 45.2% to 68.8%. Without PVP, Cu2O particles exhibited severe agglomeration and irregular morphology, resulting in limited interfacial contact with MIL-160 and low ethylene selectivity. After adding 1.6 g of PVP, PVP began to exert its crystal plane guiding and steric hindrance effects, leading to more regular Cu2O morphology, improved dispersion, and the initial formation of the heterostructure interface, thus increasing the ethylene efficiency to 56.5%. When 3.3 g of polyvinylpyrrolidone (PVP) was added, the adsorption of Cu2O crystal faces by PVP tended to saturate, forming a highly regular cubic morphology with uniform particle size and optimal particle dispersibility. This maximized heterogeneous interfacial contact with MIL-160 and achieved an ideal hydrophobic-hydrophilic balance, synergistically promoting CO2 enrichment, inhibiting hydrogen evolution, and reducing the CC coupling barrier. These structural advantages jointly promoted the dual optimization of electronic structure and three-phase interfacial microenvironment in the MIL-160 / Cu2O heterostructure catalyst, thus exhibiting the best multi-carbon product selectivity and activity in the electrocatalytic CO2 reduction reaction, and therefore achieving the optimal ethylene Faradaic efficiency.

[0076] Figure 6 The results showed that in Example 4, as the concentration of ascorbic acid solution increased from 0.4 mol / L to 0.8 mol / L, the ethylene Faradaic efficiency of the MIL-160 / Cu2O heterostructure catalyst exhibited a volcano-like trend of first increasing and then decreasing. When the ascorbic acid concentration was 0.4 mol / L, the reduction rate was slow, the number of Cu2O nuclei was limited, the particle size was relatively large, the specific surface area was small, the heterostructure interface contact was insufficient, and the ethylene efficiency was only 51.4%. When the concentration of ascorbic acid solution added was 0.6 M, the reduction reaction rate reached an ideal level, the nucleation and growth process reached the optimal balance, a sufficient number of crystal nuclei were formed, and each crystal nucleus had adequate growth space. The crystal growth stage time was moderate, the particle size was uniform, and Cu2O particles with moderate size, narrow particle size distribution, and regular morphology were formed. The crystal faces were fully exposed, forming a tight heterostructure interface with MIL-160. + With a pure valence state and an ideal hydrophobic-hydrophilic balance, it exhibits optimal performance in the electrocatalytic CO2 reduction reaction, achieving a maximum ethylene efficiency of 68.8%. However, when the concentration further increases to 0.8 mol / L, the reduction rate becomes too rapid, leading to explosive nucleation. The Cu2O particles are too small, and some Cu... + Excessive reduction to Cu reduces the heterogeneous interface due to particle stacking, disrupts the hydrophobic-hydrophilic balance, exacerbates hydrogen evolution side reactions, and causes ethylene efficiency to drop to 47.3%.

[0077] The above examples and comparative examples fully demonstrate that the hydrophobic MIL-160 / Cu2O heterostructure catalyst provided by the present invention, through careful interface design and microenvironment regulation, exhibits extremely high selectivity, activity, and stability in the electrocatalytic reduction of CO2 to multi-carbon products, especially ethylene, showing great application potential.

Claims

1. A method for preparing a hydrophobic MIL-160 / Cu2O heterostructure catalyst, characterized in that, Includes the following steps: (1) MIL-160 metal-organic framework was prepared by hydrothermal method; (2) Disperse the MIL-160 metal-organic framework in a solvent, add polyvinylpyrrolidone and copper salt, and stir until completely dissolved; (3) Add an alkaline solution to the solution obtained in step (2) and stir thoroughly to obtain a blue-green Cu(OH)2 suspension, which then turns dark brown; (4) Add a reducing agent to the Cu(OH)2 suspension obtained in step (3), heat and stir, centrifuge the product after reaction, wash and dry it to obtain the hydrophobic MIL-160 / Cu2O heterostructure catalyst.

2. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, The molar ratio of MIL-160 to Cu2O in the MIL-160 / Cu2O heterostructure catalyst is 3:1 to 1:

3.

3. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, In step (2), the mass ratio of the MIL-160 metal-organic framework to the copper salt is 2.6:1 to 1:0.15; the mass ratio of the polyvinylpyrrolidone to the copper salt is 0 to 9.6:

1.

4. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, The concentration of the copper salt solution obtained in step (2) is 0.5-5 mM; the concentration of the alkaline solution added in step (3) is 0.1-0.5 M; and the concentration of the reducing agent added in step (4) is 0.05-0.1 M.

5. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, In step (4), the reaction temperature is 50-80℃ and the reaction time is 2-4 hours.

6. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, The copper salt in step (2) is at least one of copper nitrate, copper chloride, or copper sulfate; the reducing agent in step (4) is glucose or ascorbic acid solution.

7. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, In step (3), an alkaline solution is added slowly and evenly at a rate of 4-6 ml / min using a syringe pump at room temperature to adjust the pH of the reaction system to 9.0-11.

0. The stirring speed is 500-800 rpm.

8. The method for preparing the hydrophobic MIL-160 / Cu2O heterostructure catalyst according to claim 1, characterized in that, In step (4), the reducing agent is added slowly and evenly using a syringe pump at a rate of 1-3 ml / min, and the stirring speed is 400-600 rpm.

9. The application of a hydrophobic MIL-160 / Cu2O heterostructure catalyst obtained by the method of claim 1 in the electrocatalytic carbon dioxide reduction reaction.

10. The application according to claim 9, characterized in that, The application uses an electrocatalytic carbon dioxide reduction system, which includes a catalytic electrode made from the catalyst obtained in claim 1, an electrolytic cell, a gas supply device, and an electrochemical workstation. The electrolytic cell is a flow cell, and an anion exchange membrane is provided between the cathode chamber and the anode chamber.

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