Graded self-assembly dissimilar metal cluster-based MOFs material, preparation method and application thereof
The synthesis of graded self-assembled heterometallic cluster-based MOFs materials addresses the challenge of designing multi-active sites for CO2 reduction and C-N coupling, achieving efficient urea production with improved catalytic performance through a simple and controlled solvothermal process.
Patent Information
- Application Number
- CN202510398451.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-07-15
AI Technical Summary
The prior art is difficult to accurately design MOFs materials with multi-active sites. The process of electrocatalyzing carbon dioxide reduction and urea synthesis is complicated, and the catalytic performance of existing catalysts is insufficient under mild conditions.
The hierarchical self-assembly strategy was adopted to prepare heterometal cluster-based MOFs materials through coordination drive method, increase metal sites step by step, and build multi-site efficient catalysts. A simple one-pot solvent-thermal synthesis method was used.
The efficient electrocatalytic synthesis of urea under mild conditions has been achieved, the catalytic active sites have gradually increased, the electron transfer rate has accelerated, and the catalytic performance has been significantly improved. The Faraday efficiency of electrocatalytic synthesis of urea has reached 45.2%.
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Figure CN120311246A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the synthesis of heterometallic cluster-based MOFs, and particularly relates to a hierarchically self-assembled heterometallic cluster-based MOFs material and a preparation method thereof. Background Art
[0002] Reducing carbon dioxide electrochemically into valuable chemical products powered by renewable electricity under ambient conditions has become a promising solution for achieving carbon neutrality and alleviating the greenhouse effect.
[0003] Early studies have shown that by rationally designing electrocatalysts or constructing coupled electrocatalytic reaction systems, carbon dioxide can be effectively electrochemically reduced into a variety of carbon-containing products. These products include single-carbon (C1) and multi-carbon (C 2+ ) compounds, such as CO, formate, hydrocarbons, and alcohols characterized by C-H, C-C, and / or C-O bonds.
[0004] Based on carbon dioxide reduction, organic compounds (such as acetamide, urea, methylamine, formamide, etc.) are prepared by electrochemical C-N coupling to increase the diversity of products. Urea is highly anticipated as an excellent nutrient carrier and an important fertilizer in agriculture.
[0005] Metal-organic frameworks (MOFs) have become candidate materials for achieving high-performance electrocatalytic reduction of carbon dioxide due to their clear structure, high porosity, large specific surface area, diverse components, and easy customization.
[0006] Since the electrocatalytic and urea synthesis reaction processes involve multiple complex processes such as molecular adsorption, activation, and coupling, it is difficult to precisely design and synthesize MOF materials with multiple active sites. Summary of the Invention
[0007] This application provides a hierarchically self-assembled heterometallic cluster-based MOFs material and a preparation method thereof, which are simple to operate, have a short cycle, clear structural sites, adopt a coordination-driven hierarchical self-assembly strategy, and ingeniously prepare a series of heterometallic cluster-based MOFs with gradually increasing metal sites, constructing a highly efficient catalyst with multiple sites.
[0008] To this end, the first aspect of this application provides a hierarchically self-assembled heterometallic cluster-based MOFs material, and the technical solution adopted is as follows: A hierarchically self-assembled heterometallic cluster-based MOFs material, The chemical formulas of the heterometallic cluster-based MOFs material are respectively: C 234 H 156 Ag2In 21 N 39 O 90 、C 234 H156 Ag8In 21 N 39 O 93 , C 234 H 156 Ag 11 In 21 N 45 O 112 .
[0009] The above hierarchically self-assembled heterometallic cluster-based MOF materials are all crystallized in the hexagonal crystal system, and the space groups are all P6 3 mc , and the unit cell parameters are: a = 35.9485, b = 35.9485, c = 22.1901, α = 90°, β = 90°, γ = 120°, V = 24834 Å 3 ; a = 35.7771, b = 35.7771, c = 22.0687, α = 90°, β = 90°, γ = 120°, V = 24463 Å 3 ; a = 36.0401, b = 36.0401, c = 22.2534, α = 90°, β = 90°, γ = 120°, V = 25032.2 Å 3 ; Among them, a, b, and c respectively represent the axial lengths of the unit cell, unit: Å, α, β, and γ respectively represent the axial angles of the crystal, and V represents the volume of the unit cell.
[0010] In the second aspect of the present application, a method for preparing the above hierarchically self-assembled heterometallic cluster-based MOF materials is provided, including the following steps: S1. Weigh metal indium salt and metal silver salt, and put the weighed metal salts into the polytetrafluoroethylene liner of the autoclave; S2. Weigh the organic ligand, and the organic ligand is an asymmetric organic ligand, and put the weighed organic ligand into the polytetrafluoroethylene liner of the autoclave; S3. Put the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 h; S4. Tighten the autoclave of S3 and put it into the oven, heat the oven to 120 - 150 °C, and react at 120 - 150 °C for 40 - 50 h, then let the oven cool down to 10 - 25 °C naturally to obtain the heterometallic cluster MOF material; S5. Rinse the heterometallic cluster MOF material generated in S4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure heterometallic cluster MOF material.
[0011] Preferably, the mass ratio of the metal silver salt to the metal indium salt in S1 is 1:1 to 3:1.
[0012] Preferably, the mass ratio of the organic ligand to the indium metal salt in S2 is 1:1 to 1:3.
[0013] Preferably, the organic solvent in S3 is acetonitrile and a nitrogen-containing solvent: N,N-dimethylformamide or N,N-dimethylacetamide, wherein the volume ratio of the nitrogen-containing solvent to acetonitrile is 1:30 to 1:2.
[0014] Preferably, the indium metal salt in S1 is one of indium trifluoromethanesulfonate, indium nitrate, and indium chloride; the silver metal salt is one of silver nitrate, silver trifluoromethanesulfonate, silver tetrafluoroborate, silver hexafluorophosphate, and silver trifluoroacetate.
[0015] Preferably, the coordination asymmetric organic ligand in S2 includes one of isonicotinic acid with a substituent at the 2-position of the benzene ring and isophthalic acid.
[0016] Preferably, the isonicotinic acid with a substituent at the 2-position of the benzene ring includes: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, and 2-bromoisonicotinic acid.
[0017] Preferably, the total amount of the indium metal salt, silver metal salt, and organic ligand in S3 is 30 - 60 mg, and the total amount of the organic solvent used is 3 - 6 mL.
[0018] In the third aspect of the present application, an application of the hierarchically self-assembled heterometallic cluster-based MOFs material is provided, which is mainly used for electrocatalytic reduction of CO2 to prepare urea.
[0019] The working principle and beneficial effects of the present application are as follows: 1. The present invention directly and controllably synthesizes the hierarchically self-assembled heterometallic MOFs material by a simple one-pot solvothermal method, which is simple to operate and has a short cycle.
[0020] 2. The obtained heterometallic MOFs material of the present invention is a crystalline material, and the clear structural sites are crucial for establishing the relationship between structure and properties.
[0021] 3. The present invention adopts a coordination-driven hierarchical self-assembly strategy to skillfully prepare a series of heterometallic cluster-based MOFs with gradually increasing metal sites, and successfully constructs an efficient catalyst with multiple sites.
[0022] 4. In the test of electrocatalytic C-N coupling for preparing urea, the obtained heterometallic cluster-based MOFs catalyst of the present invention exhibits excellent performance in synthesizing urea. With the gradual construction of metal sites in the heterometallic cluster-based MOFs, the electrochemically active sites gradually increase, the electron transfer rate gradually accelerates, and the catalytic performance gradually improves.
[0023] 5. As an electrocatalyst, the heterometallic cluster-based MOFs obtained in this invention have a Faraday efficiency of 45.2% for electrocatalytic urea synthesis at a potential of -0.5 V. This material has an atomically precise structure that can clarify the catalytic sites and achieve the preparation of urea through electrocatalytic C-N coupling under mild conditions, which is difficult to achieve with existing metal-organic framework-based catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The following further describes this application in detail with reference to the drawings and specific embodiments.
[0025] Figure 1 Ball-and-stick model diagrams of a series of heterometallic MOFs materials prepared for this application; Figure 2 LSV curve comparison diagrams of a series of heterometallic MOFs materials in a CO2 / Ar atmosphere for this application; Figure 3 Product distribution diagrams of a series of heterometallic MOFs materials at different potentials for this application; Figure 4 Urea product comparison diagrams of a series of heterometallic MOFs materials for this application; Figure 5 For the invention of this application 15 15N NMR diagram. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0027] To this end, the first aspect of this application provides a hierarchically self-assembled heterometallic cluster-based MOFs material, and the technical solution adopted is as follows: A hierarchically self-assembled heterometallic cluster-based MOFs material, The chemical formulas of the heterometallic cluster-based MOFs materials are respectively: C 234 H 156 Ag2In 21 N 39 O 90 、C 234 H 156 Ag8In 21 N 39 O 93 、C 234 H 156 Ag 11 In 21 N 45 O 112 .
[0028] The above hierarchically self-assembled heterometallic cluster-based MOF materials are all crystallized in the hexagonal crystal system, and the space group is P6 3 mc , and the unit cell parameters are respectively: a = 35.9485, b = 35.9485, c = 22.1901, α = 90°, β = 90°, γ = 120°, V = 24834 Å 3 ; a = 35.7771, b = 35.7771, c = 22.0687, α = 90°, β = 90°, γ = 120°, V = 24463 Å 3 ; a = 36.0401, b = 36.0401, c = 22.2534, α = 90°, β = 90°, γ = 120°, V = 25032.2 Å 3 .
[0029] Among them, a, b, and c respectively represent the axial lengths of the unit cell, unit: Å, α, β, and γ respectively represent the axial angles of the crystal, and V represents the volume of the unit cell.
[0030] In the second aspect of the present application, a method for preparing the above hierarchically self-assembled heterometallic cluster-based MOF materials is provided, including the following steps: S1. Weigh metal indium salt and metal silver salt, and put the weighed metal salts into the polytetrafluoroethylene liner of the autoclave; S2. Weigh the organic ligand, and the organic ligand is an asymmetric organic ligand, and put the weighed organic ligand into the polytetrafluoroethylene liner of the autoclave; S3. Put the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 h; S4. Tighten the autoclave of S3 and put it into the oven, heat the oven to 120 - 150 °C, and react at 120 - 150 °C for 40 - 50 h, then let the oven cool down to 10 - 25 °C naturally to obtain the heterometallic cluster MOF material; S5. Rinse the heterometallic cluster MOF material generated in S4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure heterometallic cluster MOF material.
[0031] Among them, the mass ratio of the metal silver salt to the metal indium salt in S1 is 1:1 to 3:1.
[0032] Among them, the mass ratio of the organic ligand to the metal indium salt in S2 is 1:1 to 1:3.
[0033] Among them, the organic solvent in S3 is acetonitrile and a nitrogen-containing solvent: N,N-dimethylformamide or N,N-dimethylacetamide, and the volume ratio of the nitrogen-containing solvent to acetonitrile is 1:30 to 1:2.
[0034] Among them, the indium salt in S1 is one of indium trifluoromethanesulfonate, indium nitrate, and indium chloride; the silver salt is one of silver nitrate, silver trifluoromethanesulfonate, silver tetrafluoroborate, silver hexafluorophosphate, and silver trifluoroacetate.
[0035] Among them, the coordination asymmetric organic ligand in S2 includes one of isonicotinic acid with a substituent at the 2-position of the benzene ring and isophthalic acid.
[0036] Among them, the isonicotinic acid with a substituent at the 2-position of the benzene ring includes: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, and 2-bromoisonicotinic acid.
[0037] Among them, the total amount of the indium salt, silver salt, and organic ligand in S3 is 30 - 60 mg, and the total amount of the organic solvent used is 3 - 6 mL.
[0038] In the third aspect of the present application, an application of the hierarchically self-assembled heterometallic cluster-based MOF material is provided, which is mainly used for electrocatalytic reduction of CO2 to prepare urea.
[0039] Specific embodiments of the present application are as follows: Example 1: Accurately weigh 15 mg of indium trifluoromethanesulfonate, 15 mg of silver nitrate, and 7.5 mg of isonicotinic acid and place them in the polytetrafluoroethylene inner liner of a high-pressure reaction kettle. Add 3 mL of acetonitrile and 1 mL of N,N-dimethylformamide (AR), and stir for 2 h. Place the polytetrafluoroethylene inner liner in the high-pressure reaction kettle and tighten it. Place the high-pressure reaction kettle in an oven, heat the oven to 120 °C, and react at 120 °C for 48 h. Then, wait for the oven to cool naturally to 25 °C. Wash the synthesized heterometallic cluster-based MOF alternately with 3 mL of deionized water and 3 mL of acetonitrile, and place the washed crystals in a 2 mL centrifuge tube to dry naturally.
[0040] Example 2: Accurately weigh 15 mg of indium nitrate, 15 mg of silver nitrate, and 7.5 mg of isonicotinic acid and place them in the polytetrafluoroethylene inner liner of a high-pressure reaction kettle. Add 3 mL of acetonitrile and 1 mL of N,N-dimethylformamide (AR), and stir for 2 h. Place the polytetrafluoroethylene inner liner in the high-pressure reaction kettle and tighten it. Place the high-pressure reaction kettle in an oven, heat the oven to 120 °C, and react at 120 °C for 48 h. Then, wait for the oven to cool naturally to 25 °C. Wash the synthesized heterometallic cluster-based MOF alternately with 3 mL of deionized water and 3 mL of acetonitrile, and place the washed crystals in a 2 mL centrifuge tube to dry naturally.
[0041] Example 3: 15 mg of indium trifluoromethanesulfonate, 15 mg of silver nitrate, and 7.5 mg of isonicotinic acid were placed into the PTFE liner of a high-pressure reactor. 3 mL of acetonitrile and 1 mL of N,N-dimethylacetamide (AR) were added, and the mixture was stirred for 2 h. The PTFE liner was placed into the high-pressure reactor and tightened. The high-pressure reactor was placed into an oven, which was heated to 120 °C and reacted at 120 °C for 48 h. Then, the oven was allowed to cool naturally to 25 °C. The synthesized heterometallic cluster-based MOF was washed alternately with 3 mL of deionized water and 3 mL of acetonitrile, and the washed crystals were placed into a 2 mL centrifuge tube to dry naturally.
[0042] Example 4: 15 mg of indium nitrate, 15 mg of silver nitrate, and 7.5 mg of isonicotinic acid were accurately weighed and placed into the PTFE liner of a high-pressure reactor. 3 mL of acetonitrile and 1 mL of N,N-dimethylacetamide (AR) were added, and the mixture was stirred for 2 h. The PTFE liner was placed into the high-pressure reactor and tightened. The high-pressure reactor was placed into an oven, which was heated to 120 °C and reacted at 120 °C for 48 h. Then, the oven was allowed to cool naturally to 25 °C. The synthesized heterometallic cluster-based MOF was washed alternately with 3 mL of deionized water and 3 mL of acetonitrile, and the washed crystals were placed into a 2 mL centrifuge tube to dry naturally.
[0043] Example 5: 15 mg of indium chloride, 15 mg of silver nitrate, and 7.5 mg of isonicotinic acid were accurately weighed and placed into the PTFE liner of a high-pressure reactor. 3 mL of acetonitrile and 1 mL of N,N-dimethylformamide (AR) were added, and the mixture was stirred for 2 h. The PTFE liner was placed into the high-pressure reactor and tightened. The high-pressure reactor was placed into an oven, which was heated to 120 °C and reacted at 120 °C for 48 h. Then, the oven was allowed to cool naturally to 25 °C. The synthesized heterometallic cluster-based MOF was washed alternately with 3 mL of deionized water and 3 mL of acetonitrile, and the washed crystals were placed into a 2 mL centrifuge tube to dry naturally.
[0044] Example 6: 15 mg of indium chloride, 15 mg of silver trifluoromethanesulfonate, and 7.5 mg of isonicotinic acid were accurately weighed and placed into the PTFE liner of a high-pressure reactor. 3 mL of acetonitrile and 1 mL of N,N-dimethylformamide (AR) were added, and the mixture was stirred for 2 h. The PTFE liner was placed into the high-pressure reactor and tightened. The high-pressure reactor was placed into an oven, which was heated to 120 °C and reacted at 120 °C for 48 h. Then, the oven was allowed to cool naturally to 25 °C. The synthesized heterometallic cluster-based MOF was washed alternately with 3 mL of deionized water and 3 mL of acetonitrile, and the washed crystals were placed into a 2 mL centrifuge tube to dry naturally.
[0045] Example 7: Accurately weigh 15 mg of indium chloride, 15 mg of silver trifluoromethanesulfonate, and 7.5 mg of isonicotinic acid and place them in the PTFE liner of a high-pressure reactor. Add 3 mL of acetonitrile and 1 mL of N,N-dimethylacetamide (AR), and stir for 2 h. Place the PTFE liner in the high-pressure reactor and tighten it. Put the high-pressure reactor into an oven, heat the oven to 120 °C, and react at 120 °C for 48 h. Then, wait for the oven to cool naturally to 25 °C. Wash the synthesized heterometallic cluster-based MOF alternately with 3 mL of deionized water and 3 mL of acetonitrile, and place the washed crystals in a 2 mL centrifuge tube to dry naturally.
[0046] Example 8: Accurately weigh 15 mg of indium chloride, 15 mg of silver tetrafluoroborate, and 7.5 mg of isonicotinic acid and place them in the PTFE liner of a high-pressure reactor. Add 3 mL of acetonitrile and 1 mL of N,N-dimethylacetamide (AR), and stir for 2 h. Place the PTFE liner in the high-pressure reactor and tighten it. Put the high-pressure reactor into an oven, heat the oven to 120 °C, and react at 120 °C for 48 h. Then, wait for the oven to cool naturally to 25 °C. Wash the synthesized heterometallic cluster-based MOF alternately with 3 mL of deionized water and 3 mL of acetonitrile, and place the washed crystals in a 2 mL centrifuge tube to dry naturally.
[0047] The operation of the present invention is simple. A series of hierarchically self-assembled heterometallic cluster-based MOF materials are prepared by a coordination-driven strategy. As Figure 1 shown, in the molecular structure of the series of heterometallic cluster-based MOFs, metal Ag is introduced step by step through coordination bonds.
[0048] In a 0.5 M K2SO4 solution saturated with CO2 and containing 10 mg of KNO3, the activity of the series of heterometallic cluster-based MOF materials for the electro-synthesis of urea was evaluated. As Figure 2 shown, compared with the Ar environment, in the CO2 atmosphere, the overpotential is significantly reduced and the current density is significantly increased, indicating its ability to prepare urea from CO2.
[0049] For the series of heterometallic cluster-based MOF catalyst materials of the present invention, at a potential of -0.5 V vs RHE, with the stepwise introduction of metal sites, the maximum selectivity for urea was observed to be 45.2%. As Figure 3 shown.
[0050] For the series of heterometallic cluster-based MOF catalyst materials of the present invention, with the stepwise introduction of metal sites, at a potential of -0.5 V vs. RHE, the FE for the electro-catalytic synthesis of urea increased by nearly 6 times. As Figure 4 shown.
[0051] The product of the electro-synthesis of urea by the series of heterometallic cluster-based MOF catalyst materials of the present invention was further detected by NMR. AsFigure 5 as shown
[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. Hierarchical self-assembled heterometallic cluster-based MOF materials, characterized in that: The chemical formulas of the heterometallic cluster-based MOF materials are respectively: C 234 H 156 Ag2In 21 N 39 O 90 、C 234 H 156 Ag8In 21 N 39 O 93 、C 234 H 156 Ag 11 In 21 N 45 O 112 ; The heterometallic cluster-based MOF materials are all crystallized in the hexagonal crystal system, and the space groups are all P6 3 mc , and the unit cell parameters are respectively: a = 35.9485, b = 35.9485, c = 22.1901, α = 90°, β = 90°, γ = 120°, V = 24834 Å 3 ; a = 35.7771, b = 35.7771, c = 22.0687, α = 90°, β = 90°, γ = 120°, V = 24463 Å 3 ; a = 36.0401, b = 36.0401, c = 22.2534, α = 90°, β = 90°, γ = 120°, V = 25032.2 Å 3 ; Wherein, a, b, and c respectively represent the axial lengths of the unit cell, unit: Å, α, β, and γ respectively represent the axial angles of the crystal, and V represents the volume of the unit cell.
2. A method for preparing the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 1, characterized in that: Including the following steps: S1. Weigh metal indium salts and metal silver salts, and place the weighed metal indium salts and metal silver salts into the polytetrafluoroethylene liner of the autoclave; S2. Weigh the organic ligand, and the organic ligand is an asymmetric organic ligand. Place the weighed organic ligand into the polytetrafluoroethylene liner of the autoclave; S3. Place the organic solvent into the polytetrafluoroethylene liner of the autoclave and stir at room temperature for 2 h; S4. Tighten the autoclave of S3 and place it in the oven. The oven is heated to 120 - 150 °C and reacted at 120 - 150 °C for 40 - 50 h, and then the oven is naturally cooled to 10 - 25 °C to obtain the heterometallic cluster MOF material; S5. Rinse the heterometallic cluster MOF material generated in S4 with deionized water and acetonitrile, and place it in a centrifuge tube to dry naturally to obtain a pure heterometallic cluster MOF material.
3. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The mass ratio of the metal silver salt to the metal indium salt in S1 is 1:1 to 3:
1.
4. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The mass ratio of the organic ligand to the metal indium salt in S2 is 1:1 to 1:
3.
5. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The organic solvent in S3 is acetonitrile and a nitrogen-containing solvent: N,N-dimethylformamide or N,N-dimethylacetamide. Among them, the volume ratio of the nitrogen-containing solvent to acetonitrile is 1:30 to 1:
2.
6. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The metal indium salt in S1 is one of indium trifluoromethanesulfonate, indium nitrate, and indium chloride; the metal silver salt is one of silver nitrate, silver trifluoromethanesulfonate, silver tetrafluoroborate, silver hexafluorophosphate, and silver trifluoroacetate.
7. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The coordination asymmetric organic ligand in S2 includes one of isonicotinic acid with a substituent at the 2nd position of the benzene ring and isophthalic acid.
8. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 7, characterized in that: The isonicotinic acid with a substituent at the 2nd position of the benzene ring includes: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chlorisonicotinic acid, and 2-bromisonicotinic acid.
9. The preparation method of the hierarchically self-assembled heterometallic cluster-based MOFs material according to claim 2, wherein: The total amount of the metal indium salt, metal silver salt, and organic ligand in S3 is 30 - 60 mg, and the total amount of the organic solvent used is 3 - 6 mL.
10. Use of the hierarchically self-assembled heterometallic cluster-based MOF material according to claim 1, characterized in that: For electrocatalytic conversion of carbon dioxide to urea.