Preparation method and application of copper-based metal-organic framework catalytic material

Abstract

The invention relates to the technical field of catalysts, and discloses a preparation method and application of a copper-based metal-organic framework catalytic material.The preparation method comprises the following steps that S1, cuprous salt, N, N '-bis (5-aminonicotinyl) naphthalimide and a solvent are mixed, and a mixture is obtained; s2, heating the mixture to a reaction temperature, carrying out a constant-temperature reaction, and cooling to obtain a crystal; and S3, washing and drying the crystal to obtain the copper-based metal-organic framework catalytic material. According to the preparation method of the copper-based metal-organic framework catalytic material provided by the invention, N, N '-bis (5-aminonicotinyl) naphthalimide is used as an organic ligand to prepare the copper-based metal framework Cu-PTD with N / O co-coordination, and the copper-based metal framework Cu-PTD has relatively strong electrocatalytic carbon dioxide reduction and electron transfer capabilities; and the catalyst has relatively high selectivity on electrocatalytic carbon dioxide reduction products.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a preparation method and application of a copper-based metal-organic framework catalytic material. Background Art

[0002] The electrocatalytic carbon dioxide reduction reaction (CO2RR) is a catalytic reaction that converts carbon dioxide into valuable chemicals or fuels. In this process, carbon dioxide molecules, under the action of a catalyst, undergo multi-electron and proton transfer in an electrolyte solution to form various hydrocarbons and carbon oxides, such as CO, HCOOH, and CH4. These products can be used not only as chemical feedstocks but also as energy storage media. Electrocatalytic CO2RR technology offers the potential for the efficient utilization of carbon dioxide and the reduction of greenhouse gas emissions, and is currently a hot topic of research.

[0003] However, CO2RR still faces several challenges. The linear CO2 molecule has a stable structure, and the cleavage of the C=O bond requires a high energy barrier, which limits the efficient conversion of CO2. CO2 reduction involves complex multiple electron / proton transfer steps, making the preparation of a single product a significant challenge. Furthermore, because the reaction proceeds in aqueous solution and has a low overpotential, the competing reaction—the hydrogen evolution reaction—is extremely intense, further affecting product selectivity.

[0004] Therefore, the development of efficient catalysts to achieve high activity and high selectivity in the reduction of CO2 has important research significance and application prospects. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a copper-based metal-organic framework catalytic material, comprising the following steps: S1: mixing a monovalent copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide, and a solvent to obtain a mixture; S2: heating the mixture to a reaction temperature, reacting at a constant temperature, and then cooling the mixture to obtain crystals; S3: After washing and drying the crystals, a copper-based metal-organic framework catalytic material is obtained.

[0006] Preferably, the monovalent copper salt is selected from at least one of cuprous iodide, cuprous chloride, and cuprous bromide.

[0007] Preferably, the monovalent copper salt is cuprous iodide.

[0008] Preferably, the solvent in step S1 comprises acetonitrile and N,N'-dimethylformamide.

[0009] Preferably, in step S1, the molar ratio of the monovalent copper salt to the N,N'-bis(5-aminonicotinyl)naphthalene diimide is (0.06-0.08):(0.02-0.04).

[0010] Preferably, the reaction temperature in step S2 is 100-140°C.

[0011] Preferably, the reaction temperature in step S2 is 120°C.

[0012] Preferably, the crystals are obtained after cooling to 20-40° C. in step S2.

[0013] Preferably, the heating time in step S2 is 12 hours, the constant temperature reaction time is 70-80 hours, and the cooling time is 36 hours.

[0014] Another object of the present application is to provide an application of a copper-based metal-organic framework catalytic material prepared by the preparation method of the copper-based metal-organic framework catalytic material as described above in an electrocatalytic CO2 reduction reaction.

[0015] The embodiments of the present invention have the following technical effects: The preparation method of the copper-based metal-organic framework catalytic material provided in this application uses N,N'-di(5-aminonicotinyl)naphthalene diimide as an organic ligand to prepare a copper-based metal framework Cu-PTD with N / O co-coordination, which has strong electrocatalytic carbon dioxide reduction and electron transfer capabilities, and has high selectivity for electrocatalytic carbon dioxide reduction products. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 Schematic diagram of the synthesis process of the copper-based metal-organic framework catalytic material provided in Example 1 of the present invention; Figure 2 is a crystal structure diagram of the copper-based metal-organic framework catalytic material provided in Example 1 of the present invention; Figure 3 is a Fourier transform infrared spectrum of the copper-based metal-organic framework and the H2PTD ligand provided in Example 1 of the present invention; Figure 4 is a powder diffraction PXRD pattern of the copper-based metal-organic framework provided in Example 1 of the present invention; Figure 5 Schematic diagram of the spatial coordination configuration of the copper-based metal-organic framework Cu-N2O3 provided in Example 1 of the present invention; Figure 6 This is a schematic diagram of the spatial coordination configuration of the traditional copper-based metal-organic framework Cu-N4; Figure 7 This is a Faradaic efficiency diagram of the product at a potential of -1.0 to -1.4 V vs. RHE when the Cu-N2O3 coordination material provided in Example 1 of the present invention and the traditional Cu-N4 coordination material are used as electrocatalysts; Figure 8 Graph showing the Faradaic efficiency and actual current density of multi-carbon products at a potential of -1.0 to -1.4 V vs. RHE when the Cu-N2O3 coordination material provided in Example 1 of the present invention and the traditional Cu-N4 coordination material are used as electrocatalysts. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are considered to be within the scope of the present invention. Based on the problem of low product selectivity in the existing electrocatalytic carbon dioxide reduction reaction, the present application provides a method for preparing a copper-based metal-organic framework catalytic material, which comprises the following steps: S1: mixing a monovalent copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide, and a solvent to obtain a mixture; This step can be specifically performed as follows: According to the formula, copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide (H2PTD), acetonitrile, and N,N'-dimethylformamide (DMF) were added into a heat-resistant glass vial and mixed uniformly to obtain a mixture; This step can be carried out by using ultrasonic stirring mixing method to achieve uniform mixing; S2: heating the mixture to the reaction temperature, reacting at a constant temperature, and then cooling to obtain crystals; In this step, the mixture in step S1 is sealed and then heated, reacted at a constant temperature, and then cooled. The copper salt and the organic ligand N,N'-di(5-aminonicotinyl)naphthalene diimide (H2PTD) self-assemble through coordination bonds to form a highly ordered porous structure crystalline material; S3: After washing and drying the crystals, a copper-based metal-organic framework catalytic material is obtained; In this step, the crystals obtained in step S2 are collected, washed with N,N'-dimethylformamide, and dried to obtain a copper-based metal-organic framework capable of highly efficient electrocatalytic CO2 reduction.

[0019] The preparation method of the copper-based metal-organic framework catalytic material provided in this application uses N,N'-di(5-aminonicotinyl)naphthalene diimide as an organic ligand to prepare a copper-based metal framework Cu-PTD with N / O co-coordination, which has strong electrocatalytic carbon dioxide reduction and electron transfer capabilities, and has high selectivity for electrocatalytic carbon dioxide reduction products.

[0020] In the existing electrocatalytic carbon dioxide reduction reaction, the reduction products are mostly single-carbon substances such as CO, HCOOH, and CH4. Since the electrocatalytic carbon dioxide reduction reaction generates multi-carbon (C2+) products (such as ethylene and ethanol), it is necessary to stabilize the CO intermediates and promote CC coupling, which requires two carbon atoms (usually from two different CO2 molecules or their activated intermediates) to approach and form a new carbon-carbon bond on the catalyst surface. This step is kinetically very difficult, resulting in the selectivity of multi-carbon products being much lower than that of single-carbon products. The difficulty of preparing multi-carbon products by electrocatalytic carbon dioxide reduction technology is significantly greater than that of preparing single-carbon products.

[0021] This application synthesized a copper-based metal framework with N / O co-coordination, breaking the electronic / geometric limitations of traditional symmetrical structures and providing a new approach to solving the problems of C2+ product selectivity and stability.

[0022] The present application preferably selects at least one of the monovalent copper salt from cuprous iodide, cuprous chloride, and cuprous bromide, and further preferably the monovalent copper salt is cuprous iodide.

[0023] The solvent in step S1 of the present application can be selected from at least one of acetonitrile, N,N'-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. The preferred solvent includes acetonitrile and N,N'-dimethylformamide, that is, the preferred solvent is a mixed solvent composed of acetonitrile and N,N'-dimethylformamide.

[0024] The present application preferably adopts a molar ratio of monovalent copper salt to N,N'-bis(5-aminonicotinyl)naphthalene diimide in step S1 of (0.06-0.08): (0.02-0.04); specifically, the preferred amount ratio of monovalent copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide, acetonitrile and N,N'-dimethylformamide in step S1 is (0.06-0.08) mol: (0.02-0.04) mol: 1 .35mL:1.65mL; ​​it is further preferred that the molar ratio of the monovalent copper salt to N,N'-bis(5-aminonicotinyl)naphthalene diimide in step S1 is 0.07:0.03; specifically, it is further preferred that the amount ratio of the monovalent copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide, acetonitrile, and N,N'-dimethylformamide in step S1 is 0.07mol:0.03mol:1.35mL:1.65mL.

[0025] The present application preferably adopts a reaction temperature of 100-140°C in step S2, and further preferably adopts a reaction temperature of 120°C in step S2; preferably, crystals are obtained after cooling to 20-40°C in step S2, and further preferably, crystals are obtained after cooling to 30°C in step S2.

[0026] In the preferred step S2 of the present application, the heating time is 12 hours, the constant temperature reaction time is 70-80 hours, and the cooling time is 36 hours. Furthermore, the preferred step S2 is the heating time is 12 hours, the constant temperature reaction time is 72 hours, and the cooling time is 36 hours.

[0027] As described above, the present application provides a method for preparing a novel copper-based MOFs catalytic material, which can efficiently electrocatalyze the reduction of CO2 to ethylene, ethanol, etc., and the catalyst has high selectivity for multi-carbon products.

[0028] Another object of the present application is to provide an application of a copper-based metal-organic framework catalytic material prepared by the preparation method of the copper-based metal-organic framework catalytic material as described above in an electrocatalytic CO2 reduction reaction, especially in the preparation of multi-carbon products.

[0029] The copper-based metal-organic framework catalytic material Cu-PTD prepared in this application shows high selectivity for multi-carbon products in the electrocatalytic carbon dioxide reduction reaction. Experimental results show that when the Cu-PTD material is used as an electrocatalyst, under the reaction conditions of a liquid flow cell and a mixed electrolyte of KCl and KOH with a pH value of 10, in the process of CO2 reduction to C2+, the selectivity of multi-carbon products exceeds 60% in the potential range of -1.1V~-1.2V, especially under the condition of -1.2V vs. RHE potential, the selectivity of multi-carbon products reaches 63.4%.

[0030] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] Example 1 This embodiment provides a method for preparing a copper-based metal-organic framework catalytic material, which comprises the following steps: S1: 0.07 mmol of cuprous iodide (CuI), 0.03 mmol of N,N'-bis(5-aminonicotinoyl)naphthalene diimide (H2PTTD), 1.35 ml of acetonitrile, and 1.65 ml of N,N'-dimethylformamide (DMF) were added to a heat-resistant glass vial and uniformly mixed using ultrasonic stirring to obtain a mixture; S2, sealing the mixture in step S1, heating it to 120° C. for 12 h, then conducting a constant temperature reaction for 72 h, and then cooling it to 30° C. for 36 h to obtain crystals; S3. Collect the crystals obtained in step S2, wash them with N,N'-dimethylformamide, and dry them (drying temperature 60°C, drying time 12h) to obtain the copper-based metal-organic framework catalytic material Cu-PTD that can efficiently electrocatalyze CO2 reduction.

[0032] The copper-based metal-organic framework catalytic material Cu-PTD prepared in this example was tested. See also Figure 3 As shown in the infrared spectrum of Cu-PTD prepared in this example compared with H2PTD, it can be found that the -1 The characteristic peaks corresponding to -COOH shifted on the left and right, indicating that the carboxyl group in the ligand coordinated with the Cu ion.

[0033] See also Figure 4 As shown in the figure, powder X-ray diffraction experiments show that the copper-based metal-organic framework crystallizes in the monoclinic system with unit cell parameters: a = 32.2216(15) Å, b = 10.0949(4) Å, c = 11.6015(5) Å, α = γ = 90°, β = 90.292(4)°, V = 3773.6(3), Z = 4, Z' = 1.

[0034] See also Figure 1 、 Figure 2As shown, the Cu-PTD material prepared in this embodiment is an asymmetric structure with five coordinations of N2O3. In copper-based metal organic frameworks (Cu-MOFs), asymmetric coordination has unique advantages over symmetric coordination designs, which are mainly reflected in the improvement of structural diversity, functional regulation, dynamic responsiveness and specific application performance. Specifically, when it is used in the electrocatalytic carbon dioxide reduction reaction, the co-coordination of N and O atoms causes an asymmetric distribution of the Cu+ electron cloud, which is conducive to charge transfer in the electrocatalytic process and is beneficial to the COOH, The formation of key intermediates such as COHCO reduces the energy barrier of the reaction rate-determining step, thereby making it show higher selectivity for multi-carbon products.

[0035] In order to test the electrocatalytic performance of the Cu-PTD prepared in this embodiment, this application provides the following application examples: The Cu-PTD prepared in Example 1 was placed as a catalyst in a liquid flow cell. Under the reaction conditions of a mixed electrolyte of 1 M KCl and KOH with a pH of 10, the potential range was -1.0~-1.4V, and CO2 was reduced to multi-carbon products such as ethylene, ethanol, acetic acid, and propanol).

[0036] To compare with the prior art, this application selected the reported Cu-N4 four-coordinate symmetrical structure (preparation method, see Ruo-Qin Jia, Ying-Jun Chen, Lu-Yang Zuo, et al., Enhancing the Photocatalytic Degradation Efficiency of Dyes of Copper-Based Metal-Organic Frameworks through a Dimension Induced Structural Strategy, Inorganic Chemistry, 2023, 62: 442-453) and compared the electrocatalytic carbon dioxide reduction performance with the Cu-PTD material, and provided the following application comparison examples: The existing Cu-N4 tetracoordinate material was used as a catalyst in a liquid flow cell. Under the reaction conditions of a mixed electrolyte of 1M KCl and KOH with a pH of 10, the potential range was -1.0~-1.4V, and CO2 was reduced to multi-carbon products such as ethylene, ethanol, acetic acid, and propanol. Figure 7 、 Figure 8As shown in the figure, the selectivity of the existing Cu-N4 tetracoordinate material to C2+ products at -1.2 V is only 53%, which is much lower than the selectivity of Cu-PTD to C2+ products at -1.2 V. In addition, the current density at this potential is only 63 mA cm -2 , which is much lower than 126.8 mA cm of Cu-PTD. -2 .

[0037] In addition, we also compared with existing Cu-based MOF catalysts that are only coordinated by N or O. Among them, among the Cu-based MOF catalysts coordinated only by N or O, the preparation method of PcCu-Cu-O can be found in Qiu XF, Zhu HL, Huang JR, et al. Highly Selective CO2Electroreduction to C2H4Using a Metal–Organic Frameworkwith Dual Active Sites[J]. Journal of the American Chemical Society, 2021,143: 7242-7246, the preparation method of Cu(111)@Cu-THQ can be found in Zhao ZH, Zheng K, Huang NY, et al.A Cu(111)@Metal-Organic Framework as a Tandem Catalyst for Highly SelectiveCO2Electroreduction to C2H4[J]. Chemical Communications, 2021, 57: 12764-12767, and the preparation method of Cu-Bi can be found in Albo J, Perfecto-Irigaray M, Beobide G, et al. Cu / BiMetal-Organic Framework-Based Systems for an Enhanced ElectrochemicalTransformation of CO2to alcohols[J]. Journal of CO2Utilization, 2019, 33: 157-165. For the preparation method of CuO / Cu, see Chen C, Sun X, Yan X, et al. A Strategy to Control the Grain Boundary Density and Cu + / Cu 0Ratio of Cu-Based Catalysts forEfficient Electroreduction of CO2to C2Products[J]. Green Chemistry, 2020, 22:1572-1576, for the preparation of Cu-ade MOF, see Yang F, Chen A, Deng PL, et al. HighlyEfficient Electroconversion of Carbon Dioxide into Hydrocarbons by CathodizedCopper-Organic Frameworks[J]. Chemical Science, 2019, 10: 7975-7981.

[0038] The performance comparison of Cu-PTD prepared in Example 1 and existing Cu-based MOFs catalytic materials with only N or O single element coordination as catalysts is shown in Table 1: Table 1 Combined with Table 1 and Figure 7 、 Figure 8 It can be seen that the Cu-PTD material provided in the present application shows high selectivity for multi-carbon products (ethylene, ethanol, acetic acid, and propanol) in the electrocatalytic carbon dioxide reduction reaction. Experimental results show that when the Cu-PTD material is used as an electrocatalyst, under the reaction conditions of a liquid flow cell and a mixed electrolyte of KCl and KOH with a pH of 10, in the process of CO2 reduction to C2+, the selectivity of multi-carbon products exceeds 60% in the potential range of -1.1V to -1.2V, especially under the condition of -1.2V vs. RHE potential, the selectivity of multi-carbon products reaches 63.4%; and under the condition of -1.2 V vs. RHE, the current density of multi-carbon products reaches 200mA cm -2 , indicating that Cu-PTD has good electron transfer ability and good carbon dioxide reduction activity.

[0039] contrast Figure 5 、 Figure 6The Cu-PTD material is an asymmetric structure with five coordination groups of N2O3. In copper-based metal-organic frameworks (Cu-MOFs), asymmetric coordination has unique advantages over symmetric coordination designs, mainly reflected in the improvement of structural diversity, functional regulation, dynamic responsiveness, and specific application performance. This application uses the reported Cu-N4 four-coordinated symmetric structure to compare the electrocatalytic carbon dioxide reduction performance with the Cu-PTD material. It can be seen that the maximum Faradaic efficiency of the multi-carbon product of the Cu-N2O3 structure is 10.4% higher than that of the multi-carbon product of the Cu-N4 structure, and the current density is also significantly improved. Compared with the existing reported copper-based metal-organic frameworks with only N or O single element coordination, it also has significantly higher multi-carbon product Faradaic efficiency and current density, indicating that the Cu-PTD material synthesized in this application breaks the original symmetry restriction and has stronger electrocatalytic carbon dioxide reduction and electron transfer capabilities.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a copper-based metal-organic framework catalytic material, characterized in that: The steps include: S1: mixing a monovalent copper salt, N,N'-bis(5-aminonicotinyl)naphthalene diimide, and a solvent to obtain a mixture; S2: heating the mixture to a reaction temperature, reacting at a constant temperature, and then cooling the mixture to obtain crystals; S3: After washing and drying the crystals, a copper-based metal-organic framework catalytic material is obtained.

2. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The monovalent copper salt is selected from at least one of cuprous iodide, cuprous chloride, and cuprous bromide.

3. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The monovalent copper salt is cuprous iodide.

4. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The solvent in step S1 includes acetonitrile and N,N'-dimethylformamide.

5. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The molar ratio of the monovalent copper salt to the N,N'-bis(5-aminonicotinyl)naphthalene diimide in step S1 is (0.06-0.08):(0.02-0.04).

6. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The reaction temperature in step S2 is 100-140°C.

7. The method for preparing a copper-based metal-organic framework catalytic material according to claim 6, wherein: The reaction temperature in step S2 is 120°C.

8. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: In step S2, the temperature is lowered to 20-40° C. to obtain crystals.

9. The method for preparing a copper-based metal-organic framework catalytic material according to claim 1, wherein: The heating time in step S2 is 12 h, the constant temperature reaction time is 70-80 h, and the cooling time is 36 h.

10. Use of a copper-based metal-organic framework catalytic material prepared by the method for preparing a copper-based metal-organic framework catalytic material according to any one of claims 1 to 9 in an electrocatalytic CO2 reduction reaction.

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