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

Abstract

This invention relates to the field of catalyst technology, and discloses a method for preparing a copper-based metal-organic framework catalytic material and its application. The preparation method includes the following steps: S1: mixing a monovalent copper salt, N,N'-di(5-aminonicotinic acid)naphthalenediimide, and a solvent to obtain a mixture; S2: heating the mixture to the reaction temperature, reacting at a constant temperature, and then cooling to obtain crystals; S3: washing and drying the crystals to obtain the copper-based metal-organic framework catalytic material. The method for preparing the copper-based metal-organic framework catalytic material provided in this application uses N,N'-di(5-aminonicotinic acid)naphthalenediimide as an organic ligand to prepare a copper-based metal framework Cu-PTD with N / O co-coordination, which exhibits strong electrocatalytic carbon dioxide reduction and electron transfer capabilities, and high selectivity for the electrocatalytic carbon dioxide reduction products.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a method for preparing copper-based metal-organic framework catalytic materials and their applications. Background Technology

[0002] Electrocatalytic carbon dioxide reduction (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 processes 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 carbon dioxide reduction technology offers the possibility of achieving efficient utilization of carbon dioxide and reducing greenhouse gas emissions, and is currently a hot research topic.

[0003] However, CO2RR still faces several challenges. The linear CO2 molecule has a stable structure, where the breaking of the C=O bond requires a high energy barrier, which limits the efficient conversion of CO2. CO2 reduction involves complex multi-electron / proton transfer steps, making the preparation of a single product extremely challenging. Furthermore, because the reaction takes place in aqueous solution with a low overpotential, the competing reaction—the hydrogen evolution reaction—is extremely vigorous, further affecting product selectivity.

[0004] Therefore, developing highly efficient catalysts to achieve high activity and high selectivity in CO2 reduction is of great research significance and application potential. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing copper-based metal-organic framework catalytic materials, comprising the following steps:

[0006] S1: Mix monovalent copper salt, N,N'-bis(5-aminonicotinic acid)naphthalimide, and solvent to obtain a mixture;

[0007] S2: The mixture is heated to the reaction temperature, reacted at a constant temperature, and then cooled to obtain crystals;

[0008] S3: After washing and drying the crystal, a copper-based metal-organic framework catalytic material is obtained.

[0009] Preferably, the monovalent copper salt is selected from at least one of cuprous iodide, cuprous chloride, and cuprous bromide.

[0010] Preferably, the monovalent copper salt is cuprous iodide.

[0011] Preferably, the solvent in step S1 includes acetonitrile and N,N'-dimethylformamide.

[0012] Preferably, the molar ratio of the monovalent copper salt to the N,N'-bis(5-aminonicotinyl)naphthalenediimide in step S1 is (0.06~0.08):(0.02~0.04).

[0013] Preferably, the reaction temperature in step S2 is 100~140℃.

[0014] Preferably, the reaction temperature in step S2 is 120°C.

[0015] Preferably, in step S2, the crystal is obtained after cooling to 20~40℃.

[0016] Preferably, the heating time in step S2 is 12 hours, the isothermal reaction time is 70-80 hours, and the cooling time is 36 hours.

[0017] Another objective of this application is to provide an application of the copper-based metal-organic framework catalytic material prepared by the method described above in the electrocatalytic CO2 reduction reaction.

[0018] The embodiments of the present invention have the following technical effects:

[0019] The method for preparing copper-based metal-organic framework catalytic materials provided in this application uses N,N'-bis(5-aminonicotinic acid)naphthalimide as an organic ligand to prepare copper-based metal framework Cu-PTD with N / O co-coordination. Cu-PTD has strong electrocatalytic carbon dioxide reduction and electron transfer capabilities and high selectivity for electrocatalytic carbon dioxide reduction products. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the synthesis process of the copper-based metal-organic framework catalytic material provided in Example 1 of the present invention;

[0022] Figure 2 This is a crystal structure diagram of the copper-based metal-organic framework catalytic material provided in Example 1 of the present invention;

[0023] Figure 3 This is the Fourier transform infrared spectrum of the copper-based metal-organic framework and H2PTD ligand provided in Embodiment 1 of the present invention;

[0024] Figure 4 This is the powder diffraction (PXRD) pattern of the copper-based metal-organic framework provided in Example 1 of this invention;

[0025] Figure 5 This is a schematic diagram of the spatial coordination configuration of the copper-based metal-organic framework Cu-N2O3 provided in Embodiment 1 of the present invention;

[0026] Figure 6 This is a schematic diagram of the spatial coordination configuration of the traditional copper-based metal-organic framework Cu-N4;

[0027] Figure 7 This is a Faraday efficiency diagram of the products at -1.0 to -1.4 V vs. RHE potential when the Cu-N2O3 coordination material provided in Example 1 of this invention and the traditional Cu-N4 coordination material are used as electrocatalysts.

[0028] Figure 8 This is a graph showing the Faraday efficiency and actual current density of the multi-carbon products at potentials of -1.0 to -1.4 V vs. RHE when the Cu-N2O3 coordination material provided in Example 1 of this invention and the traditional Cu-N4 coordination material are used as electrocatalysts. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are part of this invention.

[0030] To address the issue of low product selectivity in existing electrocatalytic carbon dioxide reduction reactions, this application provides a method for preparing copper-based metal-organic framework catalytic materials, which includes the following steps:

[0031] S1: Mix monovalent copper salt, N,N'-bis(5-aminonicotinic acid)naphthalimide, and solvent to obtain a mixture;

[0032] This step can be performed as follows:

[0033] According to the formula, copper salt, N,N'-bis(5-aminonicotinic acid)naphthalenediimide (H2PTD), acetonitrile, and N,N'-dimethylformamide (DMF) were added to a high-temperature resistant glass vial and mixed evenly to obtain a mixture;

[0034] This step can be achieved by using ultrasonic stirring and mixing to ensure uniform mixing;

[0035] S2: Heat the mixture to the reaction temperature, maintain the temperature for reaction, and then cool it down to obtain crystals;

[0036] In this step, the mixture from step S1 is sealed and heated, then kept at a constant temperature for reaction, and then cooled down. The copper salt and the organic ligand N,N'-bis(5-aminonicotinic acid)naphthalimide (H2PTD) self-assemble through coordination bonds to form a highly ordered porous crystalline material.

[0037] S3: After washing and drying the crystals, a copper-based metal-organic framework catalytic material is obtained;

[0038] 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 efficiently electrocatalyzing CO2 reduction.

[0039] The method for preparing copper-based metal-organic framework catalytic materials provided in this application uses N,N'-bis(5-aminonicotinic acid)naphthalimide as an organic ligand to prepare copper-based metal framework Cu-PTD with N / O co-coordination. Cu-PTD has strong electrocatalytic carbon dioxide reduction and electron transfer capabilities and high selectivity for electrocatalytic carbon dioxide reduction products.

[0040] In existing electrocatalytic carbon dioxide reduction reactions, the reduction products are mostly single-carbon substances such as CO, HCOOH, and CH4. However, the formation of multi-carbon (C2+) products (such as ethylene and ethanol) through electrocatalytic carbon dioxide reduction requires stability. The CO intermediate promotes C-C coupling, which requires two carbon atoms (usually from two different CO2 molecules or their activated intermediates) to approach each other on the catalyst surface and form new carbon-carbon bonds. This step is kinetically very difficult, resulting in a much lower selectivity for multi-carbon products compared to single-carbon products. Therefore, the preparation of multi-carbon products by electrocatalytic carbon dioxide reduction technology is significantly more difficult than the preparation of single-carbon products.

[0041] This application synthesizes 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 selectivity and stability problems of C2+ products.

[0042] The present application preferably selects the monovalent copper salt from at least one of cuprous iodide, cuprous chloride, and cuprous bromide, and further preferably selects cuprous iodide as the monovalent copper salt.

[0043] The solvent in step S1 of this application may be selected from at least one of acetonitrile, N,N'-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. Specifically, 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.

[0044] In this application, the preferred molar ratio of monovalent copper salt to N,N'-di(5-aminonicotinic acid)naphthalenediimide in step S1 is (0.06~0.08):(0.02~0.04); specifically, the preferred molar ratio of monovalent copper salt, N,N'-di(5-aminonicotinic acid)naphthalenediimide, acetonitrile, and N,N'-dimethylformamide in step S1 is (0.06~0.08) mol:(0.02~0.04) mol:1 0.35mL:1.65mL; ​​Further preferred step S1 has a molar ratio of monovalent copper salt to N,N'-bis(5-aminonicotinic acid)naphthalenediimide of 0.07:0.03; Specifically, further preferred step S1 has an amount ratio of monovalent copper salt, N,N'-bis(5-aminonicotinic acid)naphthalenediimide, acetonitrile, and N,N'-dimethylformamide of 0.07mol:0.03mol:1.35mL:1.65mL.

[0045] The preferred reaction temperature in step S2 of this application is 100~140℃, and the more preferred reaction temperature in step S2 is 120℃; preferably, crystals are obtained after cooling to 20~40℃ in step S2, and even more preferably, crystals are obtained after cooling to 30℃ in step S2.

[0046] In this application, the preferred heating time in step S2 is 12 hours, the constant temperature reaction time is 70-80 hours, and the cooling time is 36 hours. More preferably, the preferred heating time in step S2 is 12 hours, the constant temperature reaction time is 72 hours, and the cooling time is 36 hours.

[0047] As described above, this application provides a method for preparing a novel copper-based MOF catalytic material, which can efficiently electrocatalyze the reduction of CO2 to ethylene, ethanol, etc., and the catalyst has high selectivity for multi-carbon products.

[0048] Another objective of this application is to provide an application of the copper-based metal-organic framework catalytic material prepared by the method described above in the electrocatalytic CO2 reduction reaction, especially in the preparation of multi-carbon products.

[0049] The copper-based metal-organic framework catalyst Cu-PTD prepared in this application exhibits high selectivity for multi-carbon products in the electrocatalytic carbon dioxide reduction reaction. Experimental results show that when Cu-PTD is used as an electrocatalyst, under the reaction conditions of a liquid-phase flow cell and a mixed electrolyte of KCl and KOH at pH=10, the selectivity for multi-carbon products exceeds 60% in the potential range of -1.1V to -1.2V during the reduction of CO2 to C2+. In particular, the selectivity for multi-carbon products reaches 63.4% under the condition of -1.2V vs. RHE potential.

[0050] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] This embodiment provides a method for preparing a copper-based metal-organic framework catalytic material, which includes the following steps:

[0053] S1: Add 0.07 mmol of cuprous iodide (CuI), 0.03 mmol of N,N'-bis(5-aminonicotinic acid)naphthalenediimide (H2PTTD), 1.35 mL of acetonitrile, and 1.65 mL of N,N'-dimethylformamide (DMF) to a high-temperature resistant glass vial and mix them evenly using ultrasonic stirring to obtain a mixture;

[0054] S2, after sealing the mixture from step S1, first heat it to 120°C for 12 hours, then carry out a constant temperature reaction for 72 hours, and then cool it to 30°C for 36 hours to obtain crystals;

[0055] S3. Collect the crystals obtained in step S2, wash them with N,N'-dimethylformamide, and dry them (drying temperature 60℃, drying time 12h) to obtain Cu-PTD, a copper-based metal-organic framework catalyst capable of efficiently electrocatalyzing CO2 reduction.

[0056] The copper-based metal-organic framework catalytic material Cu-PTD prepared in this embodiment was tested.

[0057] See Figure 3 As shown, the infrared spectrum of Cu-PTD prepared in this embodiment, compared with that of H2PTD, reveals a position at 1560 cm⁻¹. -1 The shift in the characteristic peaks corresponding to -COOH indicates that the carboxyl group in the ligand has coordinated with the Cu ion.

[0058] See Figure 4 As shown, powder X-ray diffraction experiments revealed that the copper-based metal-organic framework crystallizes in a monoclinic system with the following 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.

[0059] See Figure 1 , Figure 2As shown, the Cu-PTD material prepared in this embodiment has a five-coordinate asymmetric structure of N2O3. In copper-based metal-organic frameworks (Cu-MOFs), asymmetric coordination has unique advantages over symmetric coordination, mainly reflected in structural diversity, functional regulation, dynamic responsiveness, and improved performance for specific applications. Specifically, when used in the electrocatalytic carbon dioxide reduction reaction, the co-coordination of N and O atoms leads to an asymmetric distribution of the Cu+ electron cloud, which facilitates charge transfer during the electrocatalytic process and is beneficial for... COOH, The formation of key intermediates such as COHCO lowers the energy barrier of the rate-determining step, thereby enabling it to exhibit high selectivity for multi-carbon products.

[0060] To test the electrocatalytic performance of the Cu-PTD prepared in this embodiment, the following application examples are provided:

[0061] The Cu-PTD prepared in Example 1 was placed in a liquid-phase flow cell as a catalyst. Under reaction conditions where the electrolyte was a mixed electrolyte of 1 M KCl and KOH at pH=10, the potential range was -1.0 to -1.4 V, reducing CO2 to multi-carbon products such as ethylene, ethanol, acetic acid, and propanol.

[0062] To compare with existing technologies, this application synthesizes a reported Cu-N4 four-coordinate symmetric 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-OrganicFrameworks through a Dimension Induced Structural Strategy, InorganicChemistry, 2023, 62: 442-453) and compares its electrocatalytic carbon dioxide reduction performance with Cu-PTD materials, providing the following application comparison examples:

[0063] Using existing Cu-N4 tetracoordinate material as a catalyst in a liquid-phase flow cell, and with a mixed electrolyte of 1M KCl and KOH at pH=10, CO2 was reduced to multi-carbon products such as ethylene, ethanol, acetic acid, and propanol within a potential range of -1.0 to -1.4 V under these conditions. (See also...) Figure 7 , Figure 8As shown, the existing Cu-N4 tetracoordinate material exhibits a C2+ product selectivity of only 53% at -1.2 V, significantly lower than that of Cu-PTD at the same potential. Furthermore, the current density at this potential is only 63 mA cm⁻¹. -2 This is far lower than the 126.8 mA cm⁻¹ of Cu-PTD. -2 .

[0064] In addition, we compared it with existing Cu-based MOF catalysts that are only coordinated with N or O. Among them, for Cu-based MOF catalysts with only N or O coordination, the preparation method of PcCu-Cu-O can be found in Qiu XF, Zhu HL, Huang JR, et al. Highly Selective CO2 Electroreduction to C2H4 Using a Metal–Organic Framework with 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 Selective CO2 Electroreduction 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.

[0065] Table 1 shows a comparative performance of the Cu-PTD prepared in Example 1 with existing Cu-based MOF catalytic materials coordinated only by N or O as catalysts:

[0066] Table 1

[0067]

[0068] Combined with Table 1 and Figure 7 , Figure 8 It is known that the Cu-PTD material provided in this application exhibits high selectivity for multi-carbon products (ethylene, ethanol, acetic acid, propanol) in the electrocatalytic carbon dioxide reduction reaction. Experimental results show that when Cu-PTD material is used as an electrocatalyst, under the reaction conditions of a liquid-phase flow cell and a mixed electrolyte of KCl and KOH at pH=10, the selectivity for multi-carbon products exceeds 60% in the potential range of -1.1V to -1.2V during the reduction of CO2 to C2+, especially reaching 63.4% under the condition of -1.2V vs. RHE; and the current density of multi-carbon products reaches 200 mA cm⁻¹ under the condition of -1.2V vs. RHE. -2 This indicates that Cu-PTD has good electron transfer capability and good carbon dioxide reduction activity.

[0069] contrast Figure 5 , Figure 6Cu-PTD material is an asymmetric structure with five coordinations of N2O3. In copper-based metal-organic frameworks (Cu-MOFs), asymmetric coordination offers unique advantages over symmetric coordination, primarily in terms of structural diversity, functional regulation, dynamic response, and enhanced performance for specific applications. This application compares the electrocatalytic carbon dioxide reduction performance of Cu-PTD material with that of the previously reported Cu-N4 four-coordination symmetric structure. The results show that the maximum Faradaic efficiency of the multi-carbon products in the Cu-N2O3 structure is 10.4% higher than that in the Cu-N4 structure, and the current density is also significantly improved. Compared to existing copper-based metal-organic frameworks with only N or O coordination, Cu-PTD material exhibits significantly higher Faradaic efficiency and current density for multi-carbon products. This indicates that the Cu-PTD material synthesized in this application breaks the original symmetry limitations and possesses stronger electrocatalytic carbon dioxide reduction and electron transfer capabilities.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate 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, Includes the following steps: S1: Mix monovalent copper salt, N,N'-bis(5-aminonicotinic acid)naphthalimide, and solvent to obtain a mixture; S2: After sealing the mixture, heat it to the reaction temperature, maintain the temperature for reaction, and then cool it down to obtain crystals; S3: After washing and drying the crystal, a copper-based metal-organic framework catalytic material is obtained; The monovalent copper salt is selected from at least one of cuprous iodide, cuprous chloride, and cuprous bromide; The solvent in step S1 is selected from at least one of acetonitrile, N,N'-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; In step S1, the molar ratio of the monovalent copper salt to the N,N'-bis(5-aminonicotinic acid)naphthalimide is (0.06~0.08):(0.02~0.04). The reaction temperature in step S2 is 100~140℃, and the constant temperature reaction time is 70-80h.

2. The preparation method of the copper-based metal-organic framework catalytic material as described in claim 1, characterized in that, The monovalent copper salt is cuprous iodide.

3. The method for preparing the copper-based metal-organic framework catalytic material as described in claim 1, characterized in that, The solvents mentioned in step S1 include acetonitrile and N,N'-dimethylformamide.

4. The method for preparing the copper-based metal-organic framework catalytic material as described in claim 1, characterized in that, The reaction temperature in step S2 is 120°C.

5. The method for preparing the copper-based metal-organic framework catalytic material as described in claim 1, characterized in that, In step S2, the temperature is lowered to 20~40℃ to obtain crystals.

6. The method for preparing the copper-based metal-organic framework catalytic material as described in claim 1, characterized in that, The heating time in step S2 is 12 hours, and the cooling time is 36 hours.

7. A copper-based metal-organic framework catalytic material, characterized in that, The copper-based metal-organic framework catalytic material was prepared by the method described in any one of claims 1-6.

8. The application of a copper-based metal-organic framework catalytic material as described in claim 7 in the electrocatalytic CO2 reduction reaction.

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