A zinc-based MOF catalyst, its preparation method and use

Abstract

The application relates to the field of carbon dioxide capture and catalytic conversion technology, in particular to a zinc-based MOF catalyst and a preparation method and application thereof. The preparation method of the zinc-based MOF catalyst comprises the following steps: mixing N , N dimethylformamide and water to obtain a mixed solvent; mixing 3-amino-1,2,4-triazole, a zinc salt and fumaric acid, dissolving the obtained reactants in the mixed solvent, and then performing a solvothermal reaction at 70 DEG C to 90 DEG C to obtain the zinc-based MOF catalyst with a column layer type three-dimensional porous network structure. The preparation method can prepare the Zn-MOF catalyst with high yield, excellent catalytic performance and low preparation cost, can electrocatalyze CO2 to be reduced to CO with high selectivity, and is favorable for wide application in the field of CO2 capture and catalytic conversion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide capture and catalytic conversion, in particular to a zinc-based MOF catalyst and a preparation method and application thereof. BACKGROUND

[0002] The gradual depletion of fossil energy and the excessive emission of carbon dioxide (CO2) have broken the dynamic balance of the carbon cycle in nature, resulting in environmental problems such as global warming and ocean acidification. Therefore, catalytic technologies for capturing CO2 and converting it into high-value chemicals and fuels have attracted much attention. Among them, the electrocatalytic CO2 reduction reaction (CO2RR) has been widely used due to its mild reaction conditions, controllable reaction rate, and the ability to achieve a benign closed carbon cycle driven by renewable energy. Therefore, developing low-cost, resource-rich, and superior-performing electrocatalysts is the key to achieving "carbon neutrality".

[0003] Metal-Organic Framework (MOF) materials are crystalline porous materials composed of metal centers and organic ligands. Due to their functional designability and structural tunability, they have wide application prospects in many fields, such as gas adsorption and separation, water treatment, sensing, and catalysis. In particular, in the field of electrocatalysis, MOF materials have unique advantages such as high specific surface area, permanent porosity, uniform pore size distribution, flexible designability, and diverse modification potential, making them an ideal electrocatalyst for CO2RR.

[0004] Zinc (Zn) is abundant in nature and has a lower cost than other transition metals, making it a significant advantage in large-scale electrocatalytic CO2RR applications. Its high electrical conductivity also facilitates efficient electron transfer during the electrocatalytic CO2RR process. Zinc-based MOF (denoted as Zn-MOF) materials combine the advantages of metal Zn and MOF materials, not only having a large specific surface area, high porosity, good thermal stability, controllable structure, excellent electrochemical performance, and other characteristics, but also being low-cost and easy to synthesize in large quantities. In the field of electrochemistry, especially in the field of electrocatalysis, it has rapidly developed and been applied. In addition, the periodic structure of MOF materials ensures the uniform distribution of high-density active sites, thereby increasing the number of surface active sites that bind CO2 molecules, providing a larger catalytic area that is conducive to catalyzing CO2RR reactions. However, traditional Zn-MOF catalysts have the defects of low yield and poor catalytic performance, which limit their application in the field of CO2 capture and catalytic conversion. SUMMARY

[0005] Therefore, it is necessary to provide a zinc-based MOF catalyst, a preparation method and application thereof, so as to solve the problems of low yield and poor catalytic performance of the traditional Zn-MOF catalyst.

[0006] The above-mentioned object of the present application is achieved by the following technical solutions.

[0007] In the first aspect of the present application, a preparation method of a zinc-based MOF catalyst is provided, comprising the following steps:

[0008] mixing N , N dimethylformamide and water to obtain a mixed solvent;

[0009] mixing 3-amino-1,2,4-triazole, a zinc salt and fumaric acid, dissolving the obtained reactants in the mixed solvent, and then performing a solvothermal reaction at 70 ℃-90 ℃ to obtain the zinc-based MOF catalyst with a columnar three-dimensional porous network structure.

[0010] In some embodiments, the zinc-based MOF catalyst belongs to a trigonal system, and the space group is .

[0011] In some embodiments, the unit cell parameters of the zinc-based MOF catalyst are a = 11.71 Å, b = 11.71 Å, c =20.77 Å, α = 90°, β = 90°, gamma = 120°, and the unit cell volume is 2467.48 Å 3 .

[0012] In some embodiments, the pore size of the zinc-based MOF catalyst is 0.5 nm-0.6 nm, and the porosity is 26%-28%.

[0013] In some embodiments, the N , N volume ratio of the dimethylformamide to the water is 1:(1.5-2.5).

[0014] In some embodiments, the zinc salt comprises one or more of zinc nitrate, zinc chloride, zinc sulfate, zinc carbonate, zinc acetate, zinc oxalate and zinc acetylacetonate.

[0015] In some embodiments, the molar ratio of the 3-amino-1,2,4-triazole, the zinc element in the zinc salt and the fumaric acid is (0.8-1.2):1:0.5.

[0016] In some embodiments, the solvothermal reaction time is 60 h to 96 h.

[0017] In a second aspect, this application provides a zinc-based MOF catalyst, which is prepared using the zinc-based MOF catalyst preparation method described above.

[0018] In a third aspect, this application provides the application of a zinc-based MOF catalyst as described above in carbon dioxide capture and catalytic conversion.

[0019] This application has at least the following beneficial effects:

[0020] In traditional techniques, the preparation of Zn-MOF catalysts using solvothermal reactions often employs mixed solvents containing DMF, but the resulting Zn-MOF catalysts suffer from low yields and poor catalytic performance. The applicant's research has revealed that even with the same ligands, the topological and crystalline structures of Zn-MOF catalysts can be drastically different. This is because the solvent plays a dual role in the synthesis of MOF materials: (1) as a structure-directing agent, solvent molecules exert dynamic regulation functions throughout the entire process from the construction of basic structural units to the formation of the final three-dimensional framework through strong interactions with metal nodes and organic ligands (such as coordination bonds, hydrogen bonds, etc.); (2) although solvent molecules only have weak interactions with the framework components, by filling the pore space and providing sufficient support, the solvent molecules can act as template agents to guide the growth of the framework around it.

[0021] Based on the above findings, the applicant, leveraging the dual effects of solvent template, synthesized Zn-MOF catalysts with different topologies and crystal phase structures using different solvents. Among these, 3-amino-1,2,4-triazole (which has lost a proton) was used as a catalyst. ) as the two-dimensional layer ligand X, with fumarate ions ( Using DMF and water as template agents, the connection mode of the two ligands can be effectively controlled, resulting in a new topology and crystal phase structure for the Zn-MOF catalyst. This leads to a columnar three-dimensional porous network structure with a pore structure and active site microenvironment that are completely different from traditional Zn-MOFs, thus achieving excellent catalytic performance. Furthermore, controlling the solvothermal reaction temperature at 70 ℃~90 ℃ not only significantly improves the yield of the Zn-MOF catalyst but also greatly reduces reaction energy consumption and the requirements for the reaction equipment, thereby saving material preparation costs and facilitating large-scale production. Therefore, the preparation method provided in this application can prepare Zn-MOF catalysts with high yield, excellent catalytic performance, and low preparation cost, which is beneficial for their widespread application in CO2 capture and catalytic conversion. Attached Figure Description

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, and more completely understand the present application and the beneficial effects thereof, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

[0023] Figure 1 PXRD patterns of the products of Examples 1-4;

[0024] Figure 2 Comparison chart of two-dimensional layer, three-dimensional framework and topology structure of Zn-atz-fma(czy) and Zn-atz-fma(pcu);

[0025] Figure 3 PXRD patterns of the product of Example 1 after soaking in different solvents for 24 h;

[0026] Figure 4 VT-PXRD pattern of the product of Example 1;

[0027] Figure 5 FESEM pattern of the product of Example 1. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the following will further describe the present application in detail in combination with specific embodiments. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0029] 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 the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments of the present application, and is not intended to limit the present application.

[0030] In the present application, the meaning of "and / or" is any and all combinations of one or more relevant listed items. The meaning of "at least one" is more than one, such as one, two, and more than two. The meaning of "a plurality of" or "several" is at least two, such as two, three, etc. The meaning of "a plurality of layers" is at least two layers, such as two layers, three layers, etc., unless otherwise specifically limited. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise specifically limited.

[0031] When a range of values is disclosed, the disclosure is to be construed to include each and every value and sub-range within the range. Further, where a range of values is provided, it is understood that the upper and lower limit of the range can be combined to form a new range of values. In addition, where a number of steps is specified in a method of the application, those steps can be combined or subdivided into further steps in an alternative embodiment.

[0032] If not otherwise specified, all steps of the application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0033] In the present application, "above" or "below" includes the number itself. For example, below 1 includes 1.

[0034] In the present application, the temperature parameter, if not otherwise specified, allows for constant temperature treatment, and also allows for variation within a certain temperature range. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy range controlled by the instrument. Fluctuations within a range of, for example, ±5 °C, ±4 °C, ±3 °C, ±2 °C, ±1 °C are allowed.

[0035] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: 23 °C ± 2 °C, 25 °C ± 5 °C or 20 °C ± 5 °C.

[0036] Terminology

[0037] Unless otherwise indicated or contradictory in context, the terms or phrases used in the present application have the following meanings:

[0038] PXRD: Powder X-Ray Diffraction.

[0039] SC-XRD: Single-Crystal X-ray Diffraction

[0040] VT-PXRD: Variable-Temperature Powder X-ray Diffraction.

[0041] FESEM: Field Emission Scanning Electron Microscope.

[0042] The following provides a detailed description of the zinc-based MOF (Zn-MOF) catalyst, its preparation method, and its applications provided in this application.

[0043] In a first aspect, this application provides a method for preparing a Zn-MOF catalyst, aiming to improve the yield of the Zn-MOF catalyst and enhance its catalytic performance for CO2RR.

[0044] In some embodiments, the preparation method of the Zn-MOF catalyst includes the following steps:

[0045] S11: Mixed N , N - Dimethylformamide (DMF) and water are used to obtain a mixed solvent;

[0046] S12: Mix 3-amino-1,2,4-triazole, zinc salt and fumaric acid, dissolve the resulting reactants in a mixed solvent, and then carry out a solvothermal reaction at 70 ℃~90 ℃ to obtain a Zn-MOF catalyst with a columnar three-dimensional porous network structure.

[0047] In traditional techniques, the preparation of Zn-MOF catalysts using solvothermal reactions often employs mixed solvents containing DMF, but the resulting Zn-MOF catalysts suffer from low yields and poor catalytic performance. The applicant's research has revealed that even with the same ligands, the topological and crystalline structures of Zn-MOF catalysts can be drastically different. This is because the solvent plays a dual role in the synthesis of MOF catalysts: (1) as a structure directing agent, solvent molecules exert dynamic regulation functions throughout the entire process from the construction of basic structural units to the formation of the final three-dimensional framework through strong interactions with metal nodes and organic ligands (such as coordination bonds, hydrogen bonds, etc.); (2) although solvent molecules only have weak interactions with the framework components, by filling the pore space and providing sufficient support, the solvent molecules can act as template agents to guide the growth of the framework around it.

[0048] Leveraging the dual effects of solvent template, the applicant synthesized Zn-MOF catalysts with different topologies and crystal phases using various solvents. Among them, 3-amino-1,2,4-triazole (which lost a proton) was used as a catalyst. ) as the two-dimensional layer ligand X, with fumarate ions ( ) as a pillar ligand and DMF and water as co-template agents can effectively control the connection mode of the two ligands, so that the Zn-MOF catalyst forms a columnar three-dimensional porous network structure with completely different pore channel structure and active site microenvironment, thereby obtaining excellent catalytic performance. Meanwhile, controlling the temperature of the solvothermal reaction at 70-90 ℃ can not only significantly improve the yield of the Zn-MOF catalyst, but also greatly reduce the energy consumption of the reaction and the requirements for the reaction device, thereby saving the material preparation cost and being conducive to large-scale production. Therefore, the preparation method provided by the application can prepare a Zn-MOF catalyst with high yield, excellent catalytic performance and low preparation cost, which is conducive to wide application in the field of CO2 capture and catalytic conversion.

[0049] In some embodiments, the volume ratio of DMF to water is 1:(1.5-2.5), including but not limited to 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4 or 1:2.5, preferably 1:2.5.

[0050] In some embodiments, the zinc salt includes one or more of zinc nitrate (Zn(NO3)2), zinc chloride (ZnCl2), zinc sulfate (ZnSO4), zinc carbonate (ZnCO3), zinc acetate (Zn(CH3COO3)2), zinc oxalate (ZnC2O4) and zinc acetylacetonate (C 10 H 14 ZnO4).

[0051] It can be understood that the zinc salt is a salt compound containing zinc element, which can be a simple salt or a complex salt, such as basic zinc carbonate (2ZnCO3·3Zn(OH)2). The above-mentioned zinc salt can not contain crystal water, or can contain crystal water, such as zinc nitrate hexahydrate (Zn(NO3)2·6H2O).

[0052] In some embodiments, the molar volume ratio of the zinc element in the zinc salt to the mixed solvent is 1 / 7 mol / L-1 / 5 mol / L, including but not limited to 1 / 7 mol / L, 1 / 6.5 mol / L, 1 / 6 mol / L, 1 / 5.5 mol / L or 1 / 5 mol / L, preferably 1 / 6 mol / L.

[0053] In some embodiments, the molar ratio of 3-amino-1,2,4-triazole, zinc element in the zinc salt and fumaric acid is (0.8-1.2):1:0.5, including but not limited to 0.8:1:0.5, 0.9:1:0.5, 1:1:0.5, 1.1:1:0.5 or 1.2:1:0.5, preferably 1:1:0.5.

[0054] In some embodiments, the method for dissolving the reactants obtained by mixing 3-amino-1, 2, 4-triazole, zinc salt and fumaric acid in the mixed solvent is ultrasonic method.

[0055] In some embodiments, the temperature of the solvothermal reaction is 70 ℃-90 ℃, including but not limited to 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃, 80 ℃, 82 ℃, 84 ℃, 86 ℃, 88 ℃ or 90 ℃.

[0056] In some embodiments, the time of the solvothermal reaction is 60 h-96 h, including but not limited to 60 h, 66 h, 72 h, 78 h, 84 h, 90 h or 96 h.

[0057] In the solvothermal reaction of the present application, the yield of Zn-MOF catalyst is significantly reduced as the temperature increases, and the solvothermal reaction in the temperature range of 70 ℃-90 ℃ can not only significantly improve the yield of Zn-MOF catalyst, but also greatly reduce the energy consumption of the reaction and the requirements for the reaction device, thereby saving the cost of material preparation and being conducive to further scale-up synthesis.

[0058] In some embodiments, the solvothermal reaction is carried out under stirring.

[0059] In the traditional technology, the solvothermal reaction for synthesizing Zn-MOF catalyst usually needs to be carried out in a high-temperature and high-pressure closed reaction kettle, and it is difficult to stir, the different components in the reactants do not contact sufficiently, and the local concentration is not uniform, so that the reaction rate and the reaction yield are significantly reduced. The solvothermal reaction of the present application has a lower temperature and does not need to be carried out in a high-temperature and high-pressure closed condition, and the reaction process can be fully stirred, so that the reaction rate and the reaction yield are greatly improved.

[0060] In some embodiments, after the solvothermal reaction, the step of washing the obtained product is further included. The solvent for washing includes but is not limited to water, methanol, ethanol or isopropanol, and the washing method can be washing 1-5 times with the solvent or washing 1 h-48 h with the solvent.

[0061] In some specific embodiments, the preparation method of the Zn-MOF catalyst comprises the following steps: mixing 3-amino-1,2,4-triazole and fumaric acid according to a molar ratio of (0.8-1.2):1:0.5 to obtain a reactant; mixing DMF and water according to a volume ratio of 1:(1.5-2.5) to obtain a mixed solvent; adding the reactant into the mixed solvent according to a molar volume ratio of zinc element in the zinc salt to the mixed solvent of 1 / 7 mol / L-1 / 5 mol / L, and after ultrasonic dissolution, placing in a heating table at 70-90 ℃ for 48-96 h of solvothermal reaction; washing the obtained product with a solvent for 48-120 h to obtain the Zn-MOF catalyst.

[0062] In some embodiments, the expression of the Zn-MOF catalyst is Zn2(X)2L. Wherein, X represents a two-dimensional layer ligand, i.e. 3-amino-1,2,4-triazole losing one proton ( ); L represents a pillar ligand, i.e. fumarate ion ( ).

[0063] The two-dimensional layer ligand X is selected from 3-amino-1,2,4-triazole losing one proton ( ), and the side group of the ligand is -NH2, which is a strong electron-donating group, making the Zn-O bond relaxed, which helps to expose more Zn sites, thereby improving the catalytic performance. The pillar ligand L is selected from fumarate ion ( ) with longer chain length and rigidity, and a suitable solvent is used as a template agent to control the connection mode of the two ligands, so that the Zn-MOF catalyst forms a completely different pore structure and active site microenvironment, thereby obtaining excellent catalytic performance.

[0064] In some embodiments, the pore size of the Zn-MOF catalyst is 0.5-0.6 nm, including but not limited to 0.5 nm, 0.51 nm, 0.52 nm, 0.53 nm, 0.54 nm, 0.55 nm, 0.56 nm, 0.57 nm, 0.58 nm, 0.59 nm or 0.6 nm, preferably 0.56 nm.

[0065] In some embodiments, the porosity of the Zn-MOF catalyst is 26%-28%, including but not limited to 26%, 26.5%, 26%, 27.5% or 28%, preferably 27.1%.

[0066] In some embodiments, the Zn-MOF catalyst belongs to the trigonal system, and the space group is .

[0067] In some embodiments, the unit cell parameters of the Zn-MOF catalyst area = 11.71 Å, b = 11.71 Å, c = 20.77Å, α = 90°, β = 90°, gamma = 120°, the unit cell volume is 2467.48 Å 3 .

[0068] In a second aspect, the application provides a Zn-MOF catalyst prepared by the method for preparing a Zn-MOF catalyst described above.

[0069] In a third aspect, the application provides the use of the Zn-MOF catalyst described above in CO2 capture and catalytic conversion.

[0070] In some embodiments, the potentiostatic electrolysis experiment is carried out under a CO2 atmosphere, and the Faraday efficiency of the Zn-MOF catalyst in catalyzing the reduction of CO2 to carbon monoxide (CO) reaches 67% to 76%, and the CO product exhibits high selectivity within a potential window of 2.4 V to 3.2 V, and no other reduction products of CO2 are detected during the entire test. 2.4 V to 3.2 V.

[0071] The following will be further described in combination with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples, if not specifically stated, can be sourced from the market. The instruments used, if not specifically stated, can be sourced from the market. The processes involved, if not specifically stated, are conventional choices for those skilled in the art.

[0072] Example 1

[0073] 42 mg (0.5 mmol) of 3-amino-1,2,4-triazole, 149 mg (0.5 mmol) of zinc nitrate (ZnNO3·6H2O), and 29 mg (0.25 mmol) of fumaric acid were mixed in a molar ratio of 1:1:0.5 to obtain a reactant; 2 mL of DMF and 5 mL of water were mixed in a volume ratio of 1:2.5 in a 20 mL glass sample bottle to obtain a mixed solvent; the reactant was added to the mixed solvent, and after ultrasonic dissolution, it was placed on a heating table at 70 °C for reaction for 72 h to obtain colorless parallelepiped block crystals; after the reaction was completed, suction filtration was performed, and the product was washed with isopropanol three times and dried in air, and the obtained product was recorded as Zn-atz-fma(czy).

[0074] Examples 2-4

[0075] Examples 2-4 differ from Example 1 in the temperature of the solvothermal reaction, as follows:

[0076] Example 2: the temperature of the solvothermal reaction is 80 °C;

[0077] Example 3: the temperature of the solvothermal reaction is 100 °C;

[0078] Example 4: the temperature of the solvothermal reaction is 120 °C;

[0079] Example 5

[0080] Mix 0.84 g of 3-amino-1,2,4-triazole, 2.97 g of zinc nitrate (ZnNO3·6H2O), and 0.84 g of fumaric acid in a molar ratio of 1:1:0.5 to obtain a reactant; mix 20 mL of DMF and 50 mL of water in a volume ratio of 1:2.5 in a 100 mL round-bottom flask to obtain a mixed solvent; add the reactant to the mixed solvent, ultrasonically dissolve completely, and then stir and reflux at 90 °C for 72 h; after suction filtration, wash the obtained product with isopropanol three times and dry it in air to obtain a Zn-MOF catalyst.

[0081] Comparative Example 1

[0082] Mix 42 mg of 3-amino-1,2,4-triazole, 149 mg of zinc nitrate (ZnNO3·6H2O), and 29 mg of fumaric acid in a molar ratio of 1:1:0.5 to obtain a reactant; mix 5 mL of DMF, 4 mL of MeOH, and 2 mL of H2O in a volume ratio of 5:4:2 in a 20 mL glass sample bottle to obtain a mixed solvent; add the reactant to the mixed solvent, ultrasonically dissolve completely, and then place it on a heating table at 70 °C to react for 3 days to obtain colorless cubic block-shaped crystals; after the reaction is completed, perform suction filtration, wash repeatedly with methanol three times, and dry it in air; the obtained product is recorded as Zn-atz-fma(pcu).

[0083] Test Examples

[0084] 1. Yield and yield:

[0085] The mass of the Zn-MOF catalyst obtained in each example was weighed using an analytical balance, and the yield of the Zn-MOF catalyst was calculated based on ZnNO3·6H2O, and the results are shown in Table 1. As can be seen from Table 1, the yield of the Zn-MOF catalyst of Example 1 is 38 mg, and the yield reaches 37%. Through comparison of Examples 1-4, it is shown that as the temperature of the solvothermal reaction increases, the yield of the Zn-MOF catalyst shows a very significant downward trend. The yield of Example 5 is 1.6 g, which is improved from milligrams to grams, indicating that the preparation method has excellent scalability.

[0086] Table 1. Yield and yield of Zn-MOF catalyst

[0087]

[0088] 2. Phase characterization:

[0089] The products synthesized in Examples 1-4 were subjected to PXRD testing using an X-ray powder diffractometer Rigaku MiniFlex 600, and the results are shown in Figure 1 . Among them, Figure 1 the simulated PXRD curve of the Zn-MOF catalyst in Figure 1 is obtained by modeling. As can be seen from , the products of Examples 1-4 are highly consistent with the simulated curve, the main diffraction peaks are clearly visible and there are no obvious impurity peaks, the diffraction peaks are sharp and the baseline is smooth, and the advantages in maintaining the integrity of the material structure are obvious. As can be seen, compared with the traditional solvothermal method, the preparation method provided in the present application not only significantly improves the synthesis efficiency of the Zn-MOF catalyst, but also maintains excellent crystallinity of the obtained product, which lays an important foundation for realizing the large-scale preparation of the Zn-MOF catalyst and its practical application.

[0090] 3. Structure characterization:

[0091] Figure 2 The product Zn-atz-fma(czy) of Example 1 was subjected to SC-XRD testing using a Rigaku Xtalab Pro MM007HF DW single crystal X-ray diffractometer, and the obtained single crystal data was subjected to structure analysis using ShelXT embedded in Olex 2 , and the structure was refined using the ShelXL program, and the crystallographic data and crystal structure diagram were obtained, and the results are shown in Table 2 and .

[0092] As can be seen from Table 2, Zn-atz-fma(czy) crystallizes in the space group of trigonal crystal system, the unit cell parameters a = 11.71 Å, b = 11.71 Å, c= 20.77 Å, α = 90°, β = 90°, gamma = 120°, the unit cell volume is 2467.48 Å 3 The independent unit of Zn-atz-fma(czy) has one Zn 2+ , one ligand and half of ligand. Zn(II) adopts a four-coordinated tetrahedral configuration, and the coordination atoms are respectively from three N atoms of and one O atom of .

[0093] As shown in Figure 2 , in Zn-atz-fma(czy), Zn(II) forms a binuclear unit with , and the unit is extended in a two-dimensional plane through sharing ligand, constructing a kgm (full name kagome) layer structure with regular hexagonal channels. Then as a linear pillar supporting ligand, the carboxyl oxygen atoms at both ends are respectively coordinated with Zn 2+ in the adjacent two-dimensional layer, to accurately connect the two-dimensional layer in ABAB staggered stacking mode, and finally form a stable structure with a three-dimensional framework.

[0094] It can be found that by simplifying the crystal structure diagram of Zn-atz-fma(pcu) and Zn-atz-fma(czy) into a topological structure diagram: in Zn-atz-fma(pcu), Zn(II) is connected with ligand to form a two-dimensional sql layer, and its pillar supporting ligand bridges in the direction perpendicular to the two-dimensional layer; in Zn-atz-fma(czy), Zn(II) constructs a kgm layer structure with regular hexagonal channels with ligand, but its pillar supporting ligand is no longer perpendicular to the two-dimensional layer, and its topological symbol is (3 2 .4 4 .6 7 .7.8), which is different from Zn-atz-fma(pcu) and other Zn-MOF catalysts. The topological structure is recorded as czy in the present application. It can be seen that the product Zn-atz-fma(czy) of example 1 is completely different from Zn-atz-fma(pcu) in two-dimensional layer, three-dimensional framework and topological structure, and therefore there is also a significant gap in catalytic performance.

[0095] Table 2. Crystallographic data table of the product of example 1

[0096]

[0097] 4. Solvent stability:

[0098] PXRD test was performed after Zn-atz-fma(czy) was soaked in different solvents for 24 h, and the results are shown in Figure 3 It can be seen from Figure 3 that the Zn-MOF catalyst prepared in Example 1 still maintains a crystal state after being soaked in water (H2O), methanol (MeOH), ethanol (EtOH) and isopropanol (i-PrOH) for 24 h, and has excellent solvent stability. i

[0099] 5. Thermal stability:

[0100] VT-PXRD test was performed on Zn-atz-fma(czy) by using a Rigaku Ultima IV X-ray powder diffractometer at a temperature rising rate of 10 ℃ / min, and the results are shown in Figure 4 It can be seen from Figure 4 that Zn-atz-fma(czy) has good thermal stability and can still maintain a good crystal state when continuously heated to 400 ℃.

[0101] 6. Morphology characterization:

[0102] FESEM test was performed on the product of Example 1 by using a field emission scanning electron microscope Zeiss Gemini 300 with an energy spectrometer, and the results are shown in Figure 5 It can be seen from Figure 5 that the product of Example 1 is in a granular shape. According to the calculation based on the single crystal structure and crystallographic data of the product of Example 1, the pore size of the product is 0.56 nm, and the porosity is 27.1%.

[0103] 7. Adsorption performance:

[0104] The product of Example 1 was vacuum activated at 120 ℃ for 24 h, and then adsorption isotherm test was performed, and the results are shown in Table 3. It can be seen from Table 3 that the highest adsorption amount of Zn-atz-fma(czy) for CO2 is 2.0 mmol / g at 273 K, and the adsorption amount of Zn-atz-fma(czy) for CO2 decreases with the increase of temperature, and the highest adsorption amount of Zn-atz-fma(czy) for CO2 decreases to 1.5 mmol / g at 298 K. The highest adsorption amount of Zn-atz-fma(pcu) for CO2 at 273 K and 298 K is significantly lower than that of Zn-atz-fma(czy), which proves that the pore structure of Zn-atz-fma(czy) is more conducive to enriching CO2.

[0105] Table 3. Comparison of adsorption performance of Zn-atz-fma(czy) and Zn-atz-fma(pcu) ​

[0106]

[0107] 8. Electrocatalytic CO2RR performance test:

[0108] Constant potential electrolysis experiments were conducted on Zn-atz-fma(czy) and Zn-atz-fma(pcu) for 64 min. The reaction products were analyzed using gas chromatography, and the results are shown in Tables 4 and 5. Tables 4 and 5 show that both Zn-atz-fma(czy) and Zn-atz-fma(pcu) exhibit good electrocatalytic performance over a relatively wide potential window (…). 2.4 V~ Both exhibited high specificity and selectivity for CO products within 3.2V.

[0109] exist At a high potential of 3.2 V, the current density of Zn-atz-fma(pcu) drops to 20 mA / cm². 2 Furthermore, the CO Faraday efficiency was lower than that of H2, indicating a significant performance degradation in the catalytic system. This phenomenon may be due to: ① decreased structural stability of Zn-atz-fma(pcu) at high potentials; ② the proton reduction pathway becoming dominant under strong reducing conditions; and ③ deactivation of reactive sites.

[0110] And Zn-atz-fma(czy) in 2.4 V~ 3.2 The current density and CO Faradaic efficiency at potential V are generally higher than those of Zn-atz-fma(pcu), and neither the current density nor the CO Faradaic efficiency decreases with increasing potential, indicating superior electrocatalytic performance. This stark contrast fully demonstrates that the three-dimensional pore system of the czy topology possesses a superior electron conduction pathway, more stable active site protection, and a more rational intermediate product transport channel, thus yielding a highly efficient and stable CO2 electroreduction catalyst.

[0111] Table 4. Current density at different potentials (unit: mA / cm²) 2 )

[0112]

[0113] Table 5. Faraday efficiency at different potentials (unit: %)

[0114]

[0115] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all such possible combinations.

[0116] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for preparing a zinc-based MOF catalyst, characterized in that, Includes the following steps: mix N , N -Dimethylformamide and water, the N , N - Dimethylformamide and water are mixed in a volume ratio of 1:(1.5~2.5) to obtain a mixed solvent; A mixture of 3-amino-1,2,4-triazole, zinc salt, and fumaric acid was prepared, and the resulting reactants were dissolved in the mixed solvent. A solvothermal reaction was then carried out at 70 °C–90 °C to obtain the zinc-based MOF catalyst with a columnar three-dimensional porous network structure. The zinc-based MOF catalyst belongs to the trigonal crystal system with space group [space group missing]. .

2. The method for preparing the zinc-based MOF catalyst according to claim 1, characterized in that, The cell parameters of the zinc-based MOF catalyst are as follows: a = 11.71 Å, b = 11.71 Å, c = 20.77 Å, α = 90°, β = 90°, γ = 120°, cell volume is 2467.48 Å 3 .

3. The method for preparing the zinc-based MOF catalyst as described in claim 1, characterized in that, The zinc-based MOF catalyst has a pore size of 0.5 nm to 0.6 nm and a porosity of 26% to 28%.

4. The method for preparing the zinc-based MOF catalyst according to any one of claims 1 to 3, characterized in that, The N , N The volume ratio of dimethylformamide to water is 1:2.

5.

5. The method for preparing the zinc-based MOF catalyst according to any one of claims 1 to 3, characterized in that, The molar volume ratio of zinc in the zinc salt to the mixed solvent is 1 / 7 mol / L to 1 / 5 mol / L.

6. The method for preparing the zinc-based MOF catalyst according to any one of claims 1 to 3, characterized in that, The zinc salts include one or more of zinc nitrate, zinc chloride, zinc sulfate, zinc carbonate, zinc acetate, zinc oxalate, and zinc acetylacetonate.

7. The method for preparing the zinc-based MOF catalyst according to claim 6, characterized in that, The molar ratio of the 3-amino-1,2,4-triazole, the zinc element in the zinc salt, and the fumaric acid is (0.8~1.2):1:0.

5.

8. The method for preparing the zinc-based MOF catalyst according to any one of claims 1 to 3, characterized in that, The solvothermal reaction time is 60 h to 96 h.

9. A zinc-based MOF catalyst, characterized in that, The zinc-based MOF catalyst was prepared using the method described in any one of claims 1 to 8.

10. The application of a zinc-based MOF catalyst as described in claim 9 in carbon dioxide capture and catalytic conversion.

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