A copper-based metal-organic framework material, its preparation method and application

Abstract

This invention relates to a copper-based metal-organic framework material, its preparation method, and its applications, with the molecular formula Cu₂C. 12 N 10 H8, made from Cu + It coordinates with a 5-(3-pyridyl)-1H-tetrazole ligand to form a copper-based metal-organic framework material belonging to the monoclinic crystal system. P twenty one / n Space group; the material comprises two crystallographically independent Cu atoms. + Each Cu + The three nitrogen atoms and one pyridine nitrogen atom from the tetrazolium group of the ligand coordinate to form a tetrahedral configuration. This invention effectively solves the technical problems of poor conductivity and low charge transport efficiency caused by the porous structure of traditional metal-organic framework materials, as well as the structural collapse and insufficient electrochemical stability under strongly alkaline electrolytes and high current conditions. It can form catalytic active centers with a defined structure, single crystal form, and excellent stability, providing a highly efficient and stable catalytic material for the electrocatalytic reduction of CO2.

Description

Technical Field

[0001] This invention relates to metal-organic framework materials, and more specifically to a copper-based metal-organic framework material, its preparation method, and its applications. Background Technology

[0002] With the continuous increase in global greenhouse gas emissions, the electrochemical reduction of CO2 into high-value-added fuels and chemicals has become one of the important strategies for achieving a sustainable carbon cycle. Compared with C1 products such as CO and CH4, C2 products such as ethylene and ethanol have higher energy density and industrial application value. Therefore, the highly selective preparation of C2 products has become a core research direction in the field of CO2 electrocatalytic reduction.

[0003] Metal-organic frameworks (MOFs) are a class of crystalline porous materials formed by the self-assembly of metal nodes and organic ligands through coordination bonds. They have shown great promise in the field of electrocatalytic CO2 reduction due to their advantages such as high specific surface area, tunable structure and function, and abundant active sites. However, traditional MOFs are generally characterized by high porosity, which presents inherent drawbacks in electrocatalytic applications: on the one hand, the porous structure leads to poor conductivity and low charge transport efficiency, making it difficult to meet the demands of high-current catalysis; on the other hand, the porous framework is prone to structural collapse under strongly alkaline electrolytes and high-current conditions, resulting in insufficient electrochemical stability, which severely limits their industrial application. Summary of the Invention

[0004] To address the problems of poor conductivity, easy structural collapse under alkaline / high current conditions, and insufficient stability of traditional porous MOFs, this invention aims to provide a copper-based metal-organic framework material, its preparation method, and its applications.

[0005] The copper-based metal-organic framework material according to the present invention has the molecular formula Cu2C. 12 N 10 H8, made from Cu + It coordinates with a 5-(3-pyridyl)-1H-tetrazole ligand to form a copper-based metal-organic framework material belonging to the monoclinic crystal system, space group P21 / n; the material contains two crystallographically independent Cu... + Each Cu + The three nitrogen atoms and one pyridine nitrogen atom from the tetrazolium group of the ligand coordinate to form a tetrahedral configuration. This invention, by employing a copper-based organic framework structure with a specific coordination structure and crystal form, can obtain novel electrocatalytic materials with a defined structure and a single crystal form, providing stable active centers for efficient electrocatalytic CO2 reduction.

[0006] In a preferred embodiment, the copper-based metal-organic framework material has a dense, non-porous structure with a porosity of 0 and cell parameters of a = 8.5529(7) Å, b = 19.2690(15) Å, c = 8.7079(7) Å, and β = 108.177(2)°. In the preferred embodiment, the N2 adsorption isotherm of the copper-based metal-organic framework material at 77 K is type II, indicating a non-microporous structure; the CO2 adsorption isotherm is type IV. This invention, by constructing a dense, non-porous framework structure, avoids the problems of side reactions and uncontrollable mass transfer inherent in traditional porous MOFs, thereby improving the stability of the catalytic process and the selectivity of C2 products.

[0007] In a preferred embodiment, the copper-based metal-organic framework material exhibits structural stability below 380°C and maintains structural integrity within a pH range of 7–14. This invention, by endowing the material with excellent thermal stability and wide pH tolerance, enables it to adapt to the harsh operating conditions of alkaline electrocatalytic systems, thereby extending the material's lifespan.

[0008] The method for preparing the copper-based metal-organic framework material according to the present invention includes the following steps: dissolving 5-(3-pyridyl)-1H-tetrazole and a soluble salt of copper (e.g., copper nitrate) in an organic solvent, mixing the mixture, placing it in a reaction vessel, reacting at 140-180°C for 2-4 days, cooling to room temperature, and obtaining the copper-based metal-organic framework material by separation, washing, and drying. The present invention prepares copper-based organic frameworks with specific structures via a one-step solvothermal method, enabling controllable synthesis of the material. The process is simple, reproducible, and suitable for large-scale preparation.

[0009] In a preferred embodiment, the molar ratio of 5-(3-pyridyl)-1H-tetrazole to a soluble salt of copper is 1:1 to 1:2. By controlling the feeding ratio of the ligand to the metal salt, this invention ensures the integrity of the coordination structure, avoids the formation of impurity phases, and further improves the purity and catalytic performance of the material.

[0010] The present invention relates to the application of the copper-based metal-organic framework material described above. In a preferred embodiment, the copper-based metal-organic framework material exhibits a fast charge transport rate and low charge transfer impedance during the electrocatalytic reduction of CO2. By using this dense copper-based organic framework as an electrocatalytic material, the present invention enables the efficient conversion of CO2 to high-value C2 products, thus broadening its application in the field of energy catalysis.

[0011] In a preferred embodiment, the potential range for electrocatalytic CO2 reduction is -0.9V to -1.9V vs. RHE, more preferably -0.8V to -0.4V vs. RHE. By conducting the electrocatalytic reaction within this potential range, the present invention can effectively suppress hydrogen evolution side reactions while ensuring the reaction driving force, thereby improving energy utilization efficiency.

[0012] In a preferred embodiment, the C2 product comprises ethylene, ethanol, and acetate. In a preferred embodiment, when the potential is below -1.3V vs. RHE, the partial current density of the C2 product is greater than that of the C1 product. In a preferred embodiment, the partial current density of ethylene is not less than 100 mA·cm⁻¹. -2 This invention promotes the C2 coupling process by regulating the microenvironment and electronic structure of the catalytic center, thereby achieving highly selective preparation of high-value C2 products such as ethylene and ethanol.

[0013] In a preferred embodiment, at a potential of -1.9V vs. RHE, the material achieves a total Faradaic efficiency of not less than 65% for C2 products. This invention, by optimizing the material structure and coordination environment, can significantly improve the Faradaic efficiency of CO2 reduction to C2 products, thereby enhancing the economics of catalytic conversion.

[0014] In a preferred embodiment, the material is at 100 mA·cm -2 Continuous electrolysis at a constant current density for no less than 15 hours showed no significant degradation in electrocatalytic performance. This invention, by employing a structurally stable, alkali-resistant, and high-temperature-resistant copper-based organic framework, can maintain stable operation for extended periods at industrial-grade current densities, demonstrating potential for practical industrial applications.

[0015] The copper-based metal-organic framework material provided by this invention utilizes Cu + The coordination mode with the 5-(3-pyridyl)-1H-tetrazole ligand, the monoclinic P21 / n space group, and the tetrahedral coordination configuration effectively solve the technical problems of poor conductivity, low charge transport efficiency, easy structural collapse, and insufficient electrochemical stability caused by the porous structure of traditional metal-organic framework materials. It can form a catalytic active center with a defined structure, single crystal form, and excellent stability, providing a highly efficient and stable catalytic material for the electrocatalytic reduction of CO2, helping to achieve highly selective conversion of CO2 to high-value-added C2 products, and laying the foundation for the industrial application of metal-organic framework materials in the field of electrocatalysis. It combines structural stability, catalytic efficiency, and application feasibility. Attached Figure Description

[0016] Figure 1 The diagram shows the copper atom coordination environment of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0017] Figure 2 The image shows the three-dimensional structure of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0018] Figure 3 This is a three-dimensional packing diagram of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of the present invention.

[0019] Figure 4 The simulated XRD pattern of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention, is superimposed with the PXRD pattern after treatment with aqueous solutions at different pH values.

[0020] Figure 5 Thermogravimetric analysis curve of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0021] Figure 6 The N2 adsorption curve of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention, at 77K.

[0022] Figure 7 The CO2 adsorption curve of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0023] Figure 8 Linear sweep voltammetry (LSV) curve of electrocatalytic CO2 reduction of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0024] Figure 9 Cyclic voltammetry curves of the dense, non-porous copper-based metal-organic framework material Cuptz prepared in Example 1 of this invention at different scan rates.

[0025] Figure 10 The double-layer capacitance C of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention. dl Relationship with scan rate.

[0026] Figure 11 The Nyquist plot of electrochemical impedance spectroscopy (EIS) for the electrocatalytic CO2 reduction of Cuptz, a dense, non-porous copper-based metal-organic framework material prepared in Example 1 of this invention.

[0027] Figure 12 The bar chart shows the distribution of electrocatalytic CO2 reduction products of the dense, non-porous copper-based metal-organic framework material Cuptz prepared in Example 1 of this invention at different potentials.

[0028] Figure 13 The diagram shows the partial current density distribution of the C2 reduction product of CO2 at different potentials for the dense, non-porous copper-based metal-organic framework material Cuptz prepared in Example 1 of this invention.

[0029] Figure 14 This is a comparison of the partial current densities of the C1 and C2 products of the dense, non-porous copper-based metal-organic framework material Cuptz prepared in Example 1 of the present invention at different potentials during the electrocatalytic reduction of CO2.

[0030] Figure 15 The dense, non-porous copper-based metal-organic framework material Cuptz prepared in Example 1 of this invention operates at 100 mA·cm⁻¹. -2 Long-term stability curve of electrocatalytic CO2 reduction under constant current density. Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0033] The test equipment and parameters involved in the following embodiments are as follows:

[0034] X-ray powder diffraction characterization: X-ray powder diffraction data were collected on a Bruker D8 Advance diffractometer, operating at 40 kV and 40 mA, using graphite-monochromatized copper target X-rays (MoKα, λ = 0.71073 Å) at 2... o up to 40 o Continuous scanning within the range is completed.

[0035] X-ray single-crystal diffraction characterization and structural analysis: Single crystals of appropriate size were selected under a microscope and collected at 100 K using CuKα (λ=1.54178Å) radiation on a Bruker D8 VENTURE CMOS photon 100 diffractometer with helios mxmultilayer single-crystal diffractometer. All crystal data were corrected for Lp factor and empirical absorption correction using the SADABS program. The structure was analyzed using the direct method, and then anisotropic corrections were made for all non-hydrogen atoms on the framework using the full matrix least squares method. The coordinates of hydrogen atoms on all carbon atoms were obtained by theoretical hydrogen addition, and then isotropic corrections were made for the hydrogen atoms.

[0036] Simulation and conversion of X-ray powder diffraction patterns of single-crystal structures: completed using Mercury software.

[0037] Thermogravimetric analysis (TGA) was performed using a NETZSCH STA449F3 thermometer under a nitrogen atmosphere at a heating rate of 10 °C / min. -1 The test temperature ranges from 40℃ to 800℃.

[0038] Gas adsorption tests were performed using a Micron ASAP2020 surface area and porosity analyzer, measuring the N2 adsorption isotherm at 77 K and the CO2 adsorption isotherm at room temperature.

[0039] Electrochemical measurements were performed using a PGSTAT302N electrochemical costation (Metrohm Autolab, equipped with BA and FRA32M modules), with Nova2 as the operating and processing software. A GC 2060 gas chromatograph was used to monitor the gaseous products during the reaction, and a Quantum-I Plus 400MHz liquid NMR spectrometer was used to detect the liquid products.

[0040] The dense, non-porous copper-based metal-organic framework material according to the present invention has the molecular formula Cu2(ptz)2, which expands to Cu2C. 12 N 10 H8, with a crystal structure belonging to the monoclinic P21 / n space group, has the following cell parameters: a=8.5529(7)Å, b=19.2690(15)Å, c=8.7079(7)Å, β=108.177(2)°. It has a three-dimensional dense, non-porous stacked structure with a porosity of 0. The molecule of the dense, non-porous copper-based metal-organic framework material contains two crystallographically independent Cu atoms. + Each Cu + It coordinates with three N atoms and one pyridine N atom of the tetrazolium group from 5-(3-pyridyl)-1H-tetrazole (3-ptzH) to form a tetrahedral configuration. The dense, non-porous copper-based metal-organic framework material exhibits excellent thermal stability (stable below 380°C), chemical stability (structural integrity within the pH range of 7–14), and electrochemical stability.

[0041] The preparation method according to the present invention includes: dissolving 3-ptzH and copper nitrate separately in an organic solvent, ultrasonically homogenizing and then mixing to obtain a suspension; transferring the suspension to a reaction vessel, heating and reacting, and then naturally cooling to room temperature; filtering and collecting the product, washing it sequentially with an organic solvent, and naturally drying to obtain yellow blocky crystals, i.e., dense, non-porous copper-based metal-organic framework material Cuptz. In a preferred embodiment, the molar ratio of 3-ptzH to copper nitrate is 1:1 to 1:2. In a preferred embodiment, the organic solvent is selected from one or more of N,N'-dimethylformamide (DMF), acetonitrile, and ethanol. Adjusting the organic solvent to achieve substrate dissolution is beneficial for complete reaction and obtaining large-size, high-quality single crystals. In a preferred embodiment, the reaction is carried out at 140-180°C. In a preferred embodiment, the reaction is carried out at a constant temperature for 2-4 days. In a preferred embodiment, natural cooling is performed for 12-24 hours. In a preferred embodiment, 3-ptz is dissolved in 0.8–1 mL of DMF, and Cu(NO3)2·6H2O is dissolved in 3–5 mL of acetonitrile. The mixture is then stirred to obtain a suspension, which is reacted at 140–180 °C for 2–4 days. After the reaction is complete, the mixture is allowed to stand and cool for 12–24 hours, then filtered and washed to obtain the dense, non-porous copper-based metal-organic framework. This one-step solvent synthesis method is simple, mild, and suitable for application in the synthesis of other dense, non-porous copper-based metal-organic framework materials.

[0042] Applications according to the present invention include the use of the dense, non-porous copper-based metal-organic framework material in the electrocatalytic reduction of CO2 to prepare C2 products. In a preferred embodiment, the C2 products include ethylene, ethanol, and acetate. In a preferred embodiment, at a potential of -1.9 V vs. RHE, the material achieves a total Faradaic efficiency of over 65% for the C2 products. In a preferred embodiment, at a potential of -1.9 V vs. RHE, the ethylene Faradaic efficiency reaches 45.6%, the ethanol Faradaic efficiency is 16.6%, and the total C2 Faradaic efficiency is as high as 65.8%. In a preferred embodiment, the partial current density of ethylene reaches 207.3 mA·cm at -1.9 V. -2 This exceeds industrial-grade current density. In a preferred embodiment, the material operates at 100 mA·cm⁻¹. -2 Electrocatalytic performance showed no degradation after continuous electrolysis for more than 15 hours at constant current density.

[0043] Example 1

[0044] 3-ptz (14.7 mg, 0.1 mmol) and Cu(NO3)2·6H2O (30 mg, 0.16 mmol) were dissolved in 0.8 mL of DMF and 4 mL of acetonitrile, respectively. After sonication, the solutions were mixed to obtain a pale blue suspension. The suspension was transferred to a 10 mL stainless steel reactor lined with polytetrafluoroethylene. The temperature was increased to 160 °C at a rate of 3 °C / min using a programmed temperature rise method. The mixture was kept at this temperature for 3 days, followed by natural cooling to room temperature for 24 hours. Yellow blocky crystals were collected by filtration, washed three times with DMF, and then three times with acetonitrile. After natural drying, a dense, non-porous copper-based metal-organic framework was obtained and named Cuptz.

[0045] Material structure and composition characterization

[0046] The prepared Cuptz was characterized by X-ray single-crystal diffraction. Some parameters of the crystallographic diffraction point data collection and structural refinement of Cuptz are shown in Table 1.

[0047] Table 1 Crystal structure parameters of Cu2(ptz)2

[0048]

[0049] Cuptz belongs to the monoclinic space group P21 / n and contains two crystallographically independent Cu atoms. + With two deprotonated ptz, such as Figure 1 As shown, both Cu1 and Cu2 are coordinated with three N atoms and one pyridine N atom from the tetrazolium group of the ligand 5-(3-pyridyl)-1H-tetrazole, forming a tetrahedral coordination configuration, which in turn constructs a three-dimensional framework structure. This framework is a dense, non-porous stacked morphology, as shown in the figure. Figure 2 As shown, its filled diagram is as follows Figure 3 As shown in the figure, it can be seen that the material exhibits a tightly packed three-dimensional structure with no obvious channels or voids. Platon calculations show that the porosity of the entire structure is 0.

[0050] Material stability characterization

[0051] 1) Chemical stability: The prepared Cuptz was immersed in neutral and strongly alkaline aqueous solutions for 24 hours respectively, and then the PXRD was tested. Figure 4This is a superimposed comparison of the simulated PXRD pattern of Cuptz, the PXRD pattern of the dried sample, the PXRD pattern of the sample soaked in neutral aqueous solution for 24 hours, and the PXRD pattern of the sample soaked in strongly alkaline aqueous solution for 24 hours. The results show that the diffraction peak positions of Cuptz after treatment with aqueous solutions at different pH values ​​all belong to the initial Cuptz crystal form, and the intensity of the characteristic diffraction peaks does not change significantly, indicating that the Cuptz prepared in this invention has good chemical stability under neutral to strongly alkaline conditions with pH values ​​ranging from 7 to 14.

[0052] 2) Thermal stability: The thermal stability of Cuptz prepared in Example 1 was studied by thermogravimetric analysis, such as... Figure 5 As shown, the prepared Cuptz material exhibits no significant mass loss and maintains structural stability within 380℃, indicating that the material possesses excellent thermal stability.

[0053] Material adsorption performance characterization

[0054] 1) N2 adsorption: Figure 6 The figure shows the nitrogen adsorption isotherm of Cuptz at 77 K. As can be seen from the figure, this curve is a type II adsorption isotherm and there is no adsorption-desorption hysteresis loop, indicating that the material has no microporous structure and N2 adsorption only occurs on the material surface, verifying the non-porous characteristics of the material.

[0055] 2) CO2 adsorption: Figure 7 The figure shows the CO2 adsorption curve of Cuptz. As can be seen from the figure, the curve is a type IV adsorption isotherm, indicating that the adsorption of CO2 by Cuptz follows a monolayer-multilayer adsorption mechanism, which is beneficial to the enrichment and activation of CO2 in the electrocatalytic process.

[0056] Electrocatalytic CO2 reduction performance test

[0057] A flow cell three-electrode system was used for testing. First, the working electrode was prepared: 3 mg Cuptz was dispersed in 1 mL of isopropanol, 16 μL of Nafion solution (5 wt%) was added, and the mixture was sonicated for 30 min to form a homogeneous slurry. This slurry was then pipetted onto a 1×3 cm² plate. 2 The catalyst was naturally dried on hydrophobic carbon paper (gas diffusion layer) with a catalyst loading of approximately 1.0 mg·cm³. -2 The working electrode was assembled into the flow cell, the counter electrode was nickel foam, and the reference electrode was Ag / AgCl. The electrolyte was 1M KOH, and the CO2 flow rate was 30 sccm.

[0058] 1) Linear Scan Voltammetry (LSV): at a scan rate of 10 mV·s -1 Record LSV curves under the following conditions ( Figure 8As shown in the figure, the catalyst exhibits a significant CO2 reduction response within the test potential range. The reduction current increases significantly with a negative shift in the cathode potential, indicating that Cuptz has good electrocatalytic activity for CO2 electroreduction and can efficiently catalyze CO2 reduction over a wide potential range from -0.8V to 0V (vs. RHE). In particular, the current shows a near-linear rapid increase in the range of -0.8V to -0.4V (vs. RHE), indicating that the core high-efficiency operating potential range of Cuptz is -0.8V to -0.4V (vs. RHE).

[0059] 2) Electrochemical active surface area (ECSA): Measured by cyclic voltammetry at different scan rates (20, 40, 60, 80, 100, 120 mV·s). -1 The current response was measured in the Faraday interval (-0.3V vs. RHE ~ -0.2V vs. RHE) under these conditions. Figure 9 ), calculate the double-layer capacitance C dl To evaluate ECSA. Results showed that the C of the Cuptz electrode... dl The value is 9.04 mF·cm -2 ( Figure 10 This indicates that Cuptz has a large electrochemical active surface area and abundant catalytic active sites exposed on its surface, which is beneficial to improving the rate of electrocatalytic CO2 reduction reaction.

[0060] 3) Electrochemical Impedance Spectroscopy (EIS): EIS tests were performed at -0.4V vs. RHE potential, such as... Figure 11 As shown in the figure, the semicircle diameter of the Nyquist plot corresponds to the charge transfer resistance (Rct), which is approximately 4.4 Ω. This result indicates that the Cuptz catalyst has a low charge transfer impedance and a rapid charge transfer process at the catalyst-electrolyte interface, which is beneficial for the efficient conduction of the CO2 electroreduction reaction.

[0061] 4) Product selectivity testing: Gas chromatography (GC) and proton nuclear magnetic resonance (NMR) spectroscopy were used. 1 Quantitative analysis of gaseous and liquid products was performed using ¹H NMR. The electrochemical performance of Cuptz at different potentials (-0.9 to -1.9 V vs. RHE) was evaluated using chronoamperometry, with samples taken after 30 min of stable electrolysis at each potential. Product distribution is shown below. Figure 12As shown, this diagram illustrates the Faraday efficiency distribution of gaseous and liquid products (ethylene, ethanol, acetate, CO, methane, formic acid, hydrogen, etc.) at various potentials. The results indicate a significant improvement in the selectivity of C2 products: at a potential of -1.9V vs. RHE, the FE for ethylene reaches 45.6%, the FE for ethanol is 16.6%, and the FE for total C2 is as high as 65.8%, while the FE for CO decreases to 18.3%, and the FE for H2 is suppressed to 13.5%, demonstrating Cuptz's outstanding selectivity for C2 products.

[0062] 5) Partial current density: To further evaluate Cuptz's ability to generate C2 products in CO2 electroreduction, the partial current density of each C2 product was calculated. Figure 13 The partial current density of three C2 products—ethylene, ethanol, and acetic acid—is shown as a function of applied potential. The partial current density of each product gradually increases with voltage. The partial current density of ethylene exceeds 100 mA·cm⁻¹ at -1.5 V vs. RHE. -2 The industrial-grade current density is achieved, reaching 207.3 mA·cm² at -1.9 V vs. RHE, with increasing potential. -2 The partial current density of ethylene is dominant at all potentials, indicating that the Cuptz surface favors the CC coupling pathway for ethylene production. Figure 14 The partial current densities of C1 products (CO, methane, and formate ions) and C2 products (ethylene, ethanol, and acetate ions) were compared. The partial current density of C1 products stabilized at 70–90 mA·cm⁻¹ after a reaction of -1.1 V vs. RHE. -2 Nearly; while in the range of -0.9V vs. RHE to -1.1V vs. RHE, the partial current density of C2 products continues to increase, and when the potential is below -1.3V vs. RHE, the partial current density of C2 products exceeds that of C1 products and becomes the main contributor to the current density, which shows that Cuptz has excellent C2 selectivity.

[0063] 6) Long-term stability: In 1M KOH alkaline electrolyte, at 100mA·cm -2 A continuous electrolysis test was conducted on the Cuptz electrode for 15 hours at a constant current density, and the results are as follows: Figure 15 As shown in the figure, the operating potential fluctuation was less than ±60mV throughout the entire test, and the C2 product selectivity remained stable. This indicates that Cuptz exhibits excellent electrochemical and structural stability under alkaline conditions, meeting the requirements for long-term continuous operation.

[0064] The dense, non-porous copper-based metal-organic framework material Cuptz described in this invention can be applied to the electrocatalytic reduction of CO2 to prepare C2 products, including ethylene, ethanol, and acetate. At -1.9 V vs. RHE potential, the total Faradaic efficiency of the C2 products reaches over 65%. At 100 mA·cm⁻¹... -2 The performance does not degrade after continuous electrolysis for more than 15 hours at constant current density.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A copper-based metal-organic framework material, characterized in that, The molecular formula is Cu2C 12 N 10 H8, made from Cu + It coordinates with a 5-(3-pyridyl)-1H-tetrazole ligand to form a copper-based metal-organic framework material belonging to the monoclinic crystal system, space group P21 / n; the material contains two crystallographically independent Cu... + Each Cu + It coordinates with three N atoms from the tetrazolium group of the ligand and one N atom from the pyridine group to form a tetrahedral configuration.

2. The material according to claim 1, characterized in that, The copper-based metal-organic framework material has a dense, non-porous structure with a porosity of 0 and cell parameters of: a=8.5529(7)Å, b=19.2690(15)Å, c=8.7079(7)Å, β=108.177(2)°.

3. The material according to claim 1, characterized in that, The copper-based metal-organic framework material is structurally stable below 380°C and maintains structural integrity within a pH range of 7 to 14.

4. A method for preparing a copper-based metal-organic framework material according to any one of claims 1 to 3, characterized in that, The process includes the following steps: dissolving 5-(3-pyridyl)-1H-tetrazole and a soluble salt of copper in an organic solvent, mixing the mixture, placing it in a reaction vessel, reacting at 140~180℃ for 2~4 days, cooling to room temperature, and obtaining the copper-based metal-organic framework material by separation, washing, and drying.

5. The method according to claim 4, characterized in that, The molar ratio of 5-(3-pyridyl)-1H-tetrazole to a soluble salt of copper is 1:1 to 1:

2.

6. The use of the material according to any one of claims 1 to 3 in the electrocatalytic reduction of CO2 to prepare C2 products.

7. The application according to claim 6, characterized in that, The potential range for electrocatalytic CO2 reduction is -0.9V to -1.9V vs. RHE.

8. The application according to claim 6, characterized in that, The C2 products include ethylene, ethanol, and acetate.

9. The application according to claim 6, characterized in that, At a potential of -1.9V vs. RHE, the material has a total Faraday efficiency of not less than 65% for C2 products.

10. The application according to claim 6, characterized in that, The material is at 100 mA·cm -2 Electrocatalytic performance showed no significant degradation after continuous electrolysis for at least 15 hours at constant current density.

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