A thiacalix[4] arene-protected copper-silver nanocluster material for electro-reduction of co2 and a preparation method thereof

Abstract

The application discloses a thiacalix[4]arene-protected copper-silver nanocluster material for electro-reducing CO2 and a preparation method thereof, and belongs to the technical field of organic-inorganic hybrid catalysts. O h Symmetry, the molecular structure is composed of a truncated cubic inorganic silver core and a peripheral ligand, large ligands cover, i.e. passivate the larger face of the cubic core, small size ligands cover, i.e. passivate the smaller face of the cubic core, forming a double hydrophobic protective shell. The silver atoms on the truncated face are exposed, realizing the symmetrical construction of the cluster structure and the ordered exposure of the sites, and effectively ensuring the synthesis of the copper-silver nanocluster material with stability and activity. The faradic efficiency of the copper-silver nanocluster material for electro-catalytically reducing CO2 to CO reaches 97.76% under the condition of self-stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic-inorganic hybrid catalysts, and particularly relates to a thiacalix[4]arene-protected copper-silver nanocluster material for electro-reduction of CO2 and a preparation method thereof. BACKGROUND

[0002] Silver-based metal catalysts play an important role in the field of catalysis. Compared with bulk silver materials and silver nanoparticles, silver nanocluster materials have smaller sizes, atomically precise structures and modifiable surface ligands, and are widely used in the field of electrocatalytic CO2 reduction. Silver nanoclusters are composed of peripheral ligands and internal silver cores. The ligands can stabilize the silver core, but on the other hand, they can also excessively cover the metal core and passivate the active center. Therefore, the activity and stability of silver nanoclusters often cannot be simultaneously considered.

[0003] In patent 1: 202111041710.5, document 2: Sci. Adv. 2016, (2), e1600323, document 3: [1] Guan Zongjie. Synthesis, structure and property of calixarene and alkyne ligand-protected coin metal nanoclusters [D]., and document 4: Chemical Science, 2024, 15, 7643-7650, the method of protecting silver clusters with thiacalix[4]arene is mentioned. Patent 1 and document 2 mention its application in fluorescence, but there are no specific examples in the field of catalysis. The reason is that the stability and activity cannot be considered simultaneously. Document 3 systematically introduces the synthesis method of thiacalix[4]arene-protected silver clusters and preliminary application exploration, but the synthesis method is relatively complicated, usually involving multi-step synthesis, and the yield is low. Poor economy leads to few applications in the field of catalysis. Document 4 mentions that calixarene-protected Zr / Ag bimetallic clusters electrocatalyze CO2 reduction, but the active silver atoms exposed by the bimetallic clusters are only a few, the molecular structure is not ordered enough, and the faradic efficiency of carbon monoxide is less than 95%.

[0004] Therefore, there is an urgent need for a new technical solution in the prior art to solve this problem. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a thiacalix[4]arene-protected copper-silver nanocluster material for electro-reduction of CO2 and a preparation method thereof to solve the technical problem that the activity and stability of silver nanoclusters in the prior art cannot be considered simultaneously.

[0006] A thiacalix[4]arene-protected copper-silver nanocluster material for electro-reduction of CO2, the single-molecule chemical formula of the copper-silver nanocluster material is:312 H 372 Ag 54 Cu 24 O 153 S 56 ; the monomolecular structural formula of the copper-silver nanocluster material is: Cu 24 Ag 54 (TC4A)6(SO4) 32 ( t BuC≡C) 12 , wherein TC4A represents a thiacalix[4]arene, t BuC≡C is tert-butyl acetylene;

[0007] The crystallization of the copper-silver nanocluster material produces the following three space groups:

[0008] The first is cubic system, space group Pn-3, and the cell parameters are: α = 90°, β = 90°, γ = 90°,

[0009] The second is trigonal system, space group R-3, and the cell parameters are α = 90°, β = 90°, γ = 120°,

[0010] The third is tetragonal system, space group P4 / mnc, and the cell parameters are α = 90°, β = 90°, γ = 90°,

[0011] Wherein, a, b, c represent the axis length of three groups of unit cells respectively, α, β, γ represent the axis angle of the crystal respectively, and V represents the volume of each unit cell.

[0012] A preparation method of a thiacalix[4]arene-protected copper-silver nanocluster material for electro-reducing CO2, for preparing the thiacalix[4]arene-protected copper-silver nanocluster material for electro-reducing CO2, comprising the following steps, and the following steps are sequentially performed:

[0013] Step one, dissolving organic silver acetylide, copper sulfate pentahydrate and thiacalix[4]arene in a mixed solvent and stirring to obtain a mixture;

[0014] Step two, transferring the mixture of step one into the polytetrafluoroethylene lining of a stainless steel high-pressure reaction kettle, and buckling the cover;

[0015] Step three, after the stainless steel high-pressure reactor in step two is screwed tightly, it is transferred to an electric heating air drying oven, and kept at 80-100 degrees Celsius for 1-3 days, and then naturally cooled to room temperature, and the orange block crystal in the polytetrafluoroethylene lining is taken out;

[0016] Step four, after the block crystal obtained in step three is washed with acetonitrile, it is dried at room temperature, and the copper-silver nanocluster material is obtained.

[0017] The organic silver acetylide in step one is at least one of alkyl acetylide silver or phenyl acetylide silver.

[0018] The thiacalix[4]arene in step one is at least one of 4-tert-butyl-thiacalix[4]arene or 4-phenyl-thiacalix[4]arene.

[0019] The mass ratio of copper sulfate pentahydrate, organic silver acetylide and thiacalix[4]arene in step one is 3:2:2 to 3:1:1.

[0020] The mixed solvent in step one is a nitrogen-containing solvent, an alcohol and a third solvent, and the mass ratio of the three is 1:1:2 to 1:4:4.

[0021] The nitrogen-containing solvent is N,N-dimethylformamide or N,N-diethylformamide or N,N-dimethylacetamide; the alcohol is methanol or ethanol or n-butanol or isopropanol or n-propanol; and the third solvent is acetonitrile or tetrahydrofuran or 1,4-dioxane.

[0022] The total mass of copper sulfate pentahydrate, organic silver acetylide and thiacalix[4]arene is 50-100 mg, and the total volume of the mixed solvent used is 2-6 ml.

[0023] Through the above design scheme, the present application can bring the following beneficial effects:

[0024] 1. The present application directly synthesizes copper-silver nanocluster material by simple one-pot method, which is simple, short in cycle and high in yield, and the yield can be greater than 75% based on silver acetylide. Compared with the synthesis methods of patent 1, literature 2 and literature 3, the present application is more simple and convenient, and can greatly improve the synthesis efficiency of metal nanocluster material.

[0025] 2. The catalyst material obtained by the present application is a crystal material, which can be tested by X-ray single crystal diffractometer to obtain its determined molecular formula and molecular structure.

[0026] 3. The present application utilizes high-symmetry topological structure to design catalyst, which is unprecedented in the above-mentioned literature and patent and in the field. h The copper-silver nanocluster material in the present application is obtained by the above-mentioned dual driving, which is Oh The symmetry, the molecular structure of which is composed of a truncated cubic inorganic silver core and a peripheral ligand. In the synthesis process, the thiacalix[4]arene chelates the four-nuclear copper and four sulfate ions to form a large ligand, which covers and passivates the larger face of the cubic core, and the alkyne ligand, which covers and passivates the smaller face of the cubic core, forms a double hydrophobic protective shell. While the silver atoms on the truncated face are exposed, the symmetrical structure and the ordered exposure of the sites of the cluster structure are realized, which effectively ensures the synthesis of copper-silver nanocluster materials with stability and activity.

[0027] 4、The catalyst obtained by the application has smaller charge transfer resistance, higher selectivity and lower overpotential in the catalysis of CO2 reduction, so that it can maintain more than 80% CO faradic efficiency at a potential of-0.95 to-1.25 V vs RHE under the condition of potassium chloride as an electrolyte, and can reach a CO faradic efficiency of 97.76% at a voltage of-1.15 V vs RHE, which is higher than 90.23% in document 4 in the foregoing background art.

[0028] 5、The catalyst obtained by the application can maintain more than 70% CO faradic efficiency at a high current density of 100 mA cm-2 in a flow cell in the catalysis of CO2 reduction. -2 ~300mAcm -2 BRIEF DESCRIPTION OF DRAWINGS

[0029] The application will be further described below in combination with the drawings and specific embodiments:

[0030] Figure 1 The single molecule structure ball-stick model diagram of the copper-silver nanocluster material obtained in Example 1 of the application is determined by single crystal diffraction experiment;

[0031] Figure 2 The single molecule structure atom space filling diagram of the copper-silver nanocluster material obtained in Example 1 of the application is determined by single crystal diffraction experiment;

[0032] Figure 3 The current density comparison diagram of the copper-silver nanocluster material obtained in Example 1 of the application in linear sweep voltammetry test under CO2 / Ar atmosphere;

[0033] Figure 4 The product and its faradic efficiency diagram of the copper-silver nanocluster material obtained in Example 1 of the application in electrocatalytic CO2 reduction at different potentials;

[0034] Figure 5 The product, CO faradic efficiency and CO partial current density diagram of the copper-silver nanocluster material obtained in Example 1 of the application in electrocatalytic CO2 reduction at different current densities in a flow electrolytic cell;​

[0035] Figure 6 X-ray powder diffraction pattern (PXRD) of the copper-silver nanocluster material obtained in Example 1 of the present application;

[0036] Figure 7 Infrared spectrum of the copper-silver nanocluster material obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0037] Example 1:

[0038] Dissolve 10 milligrams of silver tert-butylacetylide, 30 milligrams of copper sulfate pentahydrate and 10 milligrams of tert-butylthiacalix[4]arene in 0.5 milliliters of N,N dimethylformamide, 0.5 milliliters of ethanol and 1 milliliter of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene lining of the stainless steel high-pressure reaction kettle, and screw the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and keep at 80 degrees Celsius for 1 day, then naturally cool to room temperature, and a large amount of orange block crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, and the copper-silver nanocluster material is obtained, which belongs to tetragonal system, and the yield is 81% based on silver acetylide.

[0039] Example 2:

[0040] Dissolve 10 milligrams of silver tert-butylacetylide, 30 milligrams of copper sulfate pentahydrate and 10 milligrams of tert-butylthiacalix[4]arene in 0.5 milliliters of N,N dimethylformamide, 0.5 milliliters of ethanol and 1 milliliter of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene lining of the stainless steel high-pressure reaction kettle, and screw the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and keep at 80 degrees Celsius for 1 day, then naturally cool to room temperature, and a large amount of orange block crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, and the copper-silver nanocluster material is obtained, which belongs to tetragonal system, and the yield is 81% based on silver acetylide.

[0041] Example 3:

[0042] Dissolve 10 milligrams of silver tert-butylacetylide, 30 milligrams of copper sulfate pentahydrate and 10 milligrams of tert-butylthiacalix[4]arene in 0.5 milliliters of N,N dimethylformamide, 0.5 milliliters of ethanol and 1 milliliter of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene lining of the stainless steel high-pressure reaction kettle, and screw the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and keep at 80 degrees Celsius for 1 day, then naturally cool to room temperature, and a large amount of orange block crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, and the copper-silver nanocluster material is obtained, which belongs to tetragonal system, and the yield is 81% based on silver acetylide.

[0043] Example 4:

[0044] Dissolve 20 mg of silver 2-ethylhex-1-yne, 50 mg of copper sulfate pentahydrate and 20 mg of 2-ethylhex-1-yne in 1 mL of N,N-dimethylformamide, 1 mL of ethanol and 2 mL of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene liner of the stainless steel high-pressure reaction kettle, and buckle the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and after keeping at 100 degrees Celsius for 1 day, naturally cool to room temperature, that is, a large amount of orange block-shaped crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, thereby obtaining the copper-silver nanocluster material, which belongs to the cubic system, and the yield is 87% based on silver acetylene.

[0045] Example 5:

[0046] Dissolve 20 mg of silver 2-ethylhex-1-yne, 50 mg of copper sulfate pentahydrate and 20 mg of 2-ethylhex-1-yne in 1 mL of N,N-dimethylformamide, 1 mL of ethanol and 2 mL of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene liner of the stainless steel high-pressure reaction kettle, and buckle the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and after keeping at 100 degrees Celsius for 1 day, naturally cool to room temperature, that is, a large amount of orange block-shaped crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, thereby obtaining the copper-silver nanocluster material, which belongs to the cubic system, and the yield is 87% based on silver acetylene.

[0047] Example 6:

[0048] Dissolve 20 mg of silver 2-ethylhex-1-yne, 50 mg of copper sulfate pentahydrate and 20 mg of 2-ethylhex-1-yne in 1 mL of N,N-dimethylformamide, 1 mL of ethanol and 2 mL of acetonitrile mixed solvent, and stir uniformly. Then transfer the above mixture into the polytetrafluoroethylene liner of the stainless steel high-pressure reaction kettle, and buckle the cover. Tighten the high-pressure reaction kettle, transfer to the electric heating drying oven, and after keeping at 100 degrees Celsius for 1 day, naturally cool to room temperature, that is, a large amount of orange block-shaped crystals appear. The obtained crystals are washed with acetonitrile, and dried at room temperature, thereby obtaining the copper-silver nanocluster material, which belongs to the cubic system, and the yield is 87% based on silver acetylene.

[0049] Example 7:

[0050] 10 mg of silver phenylacetylide, 30 mg of copper sulfate pentahydrate and 10 mg of thiacalix[4]arene were dissolved in 1 mL of N,N-dimethylacetamide, 1 mL of ethanol and 4 mL of dioxane mixed solvent, and stirred uniformly. Then the above mixture was transferred to the polytetrafluoroethylene lining of the stainless steel high-pressure reaction kettle, and the cover was buckled. The high-pressure reaction kettle was screwed, transferred to the electric heating drying oven, and after being kept at 80 degrees Celsius for 1 day, it was naturally cooled to room temperature, and a large amount of orange block-shaped crystals appeared. The obtained crystals were washed with acetonitrile and dried at room temperature, and the copper-silver nanocluster material was obtained, which belonged to the tetragonal system, and the yield was 82% based on silver acetylide.

[0051] Example 8:

[0052] 10 mg of silver phenylacetylide, 30 mg of copper sulfate pentahydrate and 10 mg of thiacalix[4]arene were dissolved in 1 mL of N,N-dimethylacetamide, 1 mL of ethanol and 4 mL of dioxane mixed solvent, and stirred uniformly. Then the above mixture was transferred to the polytetrafluoroethylene lining of the stainless steel high-pressure reaction kettle, and the cover was buckled. The high-pressure reaction kettle was screwed, transferred to the electric heating drying oven, and after being kept at 80 degrees Celsius for 1 day, it was naturally cooled to room temperature, and a large amount of orange block-shaped crystals appeared. The obtained crystals were washed with acetonitrile and dried at room temperature, and the copper-silver nanocluster material was obtained, which belonged to the tetragonal system, and the yield was 82% based on silver acetylide.

[0053] The present application is simple to operate, and a thiacalix[4]arene-protected copper-silver nanocluster catalyst material can be prepared by one-pot solvothermal method, as shown in Figure 1 and Figure 2 The molecular structure of the copper-silver nanocluster material is composed of a truncated cubic inorganic silver core and a peripheral ligand, the large ligand covers the larger

[100] face of the cubic core, the small size ligand covers the smaller

[110] face of the cubic core, forming a double hydrophobic protective shell. The silver atoms on the truncated

[111] face are exposed, realizing the synthesis of silver nanocluster material with both stability and activity. The crystal system of the crystal is closely related to the reaction temperature, and the higher the temperature, the higher the symmetry of the crystal system, that is, 80 degrees for tetragonal phase, 90 degrees for trigonal phase, and 100 degrees for cubic phase.

[0054] The copper-silver nanocluster catalyst material in the present application was evaluated for CO2RR activity in a CO2-saturated 1M KCl (pH = 4.2) solution. As shown in Figure 3 The current density in the carbon dioxide atmosphere is twice that in the Ar atmosphere, indicating that the copper-silver nanocluster catalyst has catalytic activity for CO2 reduction.

[0055] The copper silver nanocluster catalyst material in the application can maintain more than 80% CO faradaic efficiency under the condition of potassium chloride as electrolyte, and the reduction product CO is in a volcano-shaped distribution under the potential of-0.95 to-1.25 V vs RHE, especially under the voltage of-1.15 V vs RHE, the CO faradaic efficiency can reach 97.76%. As shown in Figure 4 .

[0056] The copper silver nanocluster catalyst material in the application can maintain more than 70% CO faradaic efficiency under the high current density of 100 mA cm -2 -300 mA cm -2 . As shown in Figure 5 , Figure 5 the middle columnar chart is CO faradaic efficiency, and the dotted line chart is CO partial current density.

[0057] The copper silver nanocluster catalyst material in the application can maintain stability after catalysis, and the X-ray powder diffraction pattern and Fourier transform infrared spectrum prove this point, proving that it has good stability, as shown in Figure 6 and Figure 7 . Figure 6 In the middle, a is the PXRD curve loaded on the carbon paper after reaction, b is the PXRD curve before reaction, and c is the simulated PXRD curve; Figure 7 In the middle, d is the infrared spectrum before reaction, and e is the infrared spectrum after reaction.

Claims

1. A thiacalix[4]arene-protected copper-silver nanoclusters for electroreduction of CO2, characterized in that: The single-molecule chemical formula of the copper-silver nanocluster material is: C 312 H 372 Ag 54 Cu 24 O 153 S 56 The simplified single-molecule structural formula of the copper-silver nanocluster material is: Cu 24 Ag 54 (TC4A)6(SO4) 32 ( t BuC≡C) 12 , where TC4A represents thiacalix[4] aromatics, t BuC≡C is tert-butylacetylene; The crystallization of the copper-silver nanocluster material produces the following three space groups: The first type is a cubic crystal system with space group Pn-3 and cell parameters as follows: α=90°, β=90°, γ=90°, The second type is a trigonal crystal system, space group R-3, with unit cell parameters... α=90°, β=90°, γ=120°, The third type is the tetragonal crystal system, space group P4 / mnc, with the following unit cell parameters: α=90°, β=90°, γ=90°, Where a, b, and c represent the axial lengths of the three sets of unit cells, α, β, and γ represent the axial angles of the crystal, and V represents the volume of each unit cell.

2. A method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2, used to prepare the thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 as described in claim 1, characterized in that: Including the following step, And the following steps are performed in sequence: Step 1: Dissolve organic silver acetylene, copper sulfate pentahydrate and thiacalix[4] aromatics in a mixed solvent and stir to obtain a mixture; Step 2: Transfer the mixture described in Step 1 into the polytetrafluoroethylene liner of the stainless steel high-pressure reactor and close the lid; Step 3: After tightening the stainless steel high-pressure reactor from Step 2, transfer it to an electric heating drying oven and keep it at 80-100 degrees Celsius for 1-3 days. Then let it cool naturally to room temperature and remove the orange-yellow blocky crystals that appear in the polytetrafluoroethylene liner. Step 4: Wash the bulk crystals obtained in Step 3 with acetonitrile and dry them at room temperature to obtain the copper-silver nanocluster material.

3. The method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to claim 2, characterized in that: The organic acetylene silver in step one is at least one of alkyl acetylene silver or phenyl acetylene silver.

4. The method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to claim 2, characterized in that: The thiacalix[4] aromatic in step one is at least one of 4-tert-butyl-thiacalix[4] aromatic and 4-phenyl-thiacalix[4] aromatic.

5. The method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to claim 2, characterized in that: The mass ratio of copper sulfate pentahydrate, organic silver alkynylene, and thiacalix[4] aromatic hydrocarbon in step one is 3:2:2 to 3:1:

1.

6. The method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to claim 2, characterized in that: The mixed solvent in step one is a nitrogen-containing solvent, an alcohol, and a third solvent, with a mass ratio of 1:1:2 to 1:4:

4.

7. The method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to claim 6, characterized in that: The nitrogen-containing solvent is N,N-dimethylformamide, N,N-diethylformamide, or N,N-dimethylacetamide; the alcohol is methanol, ethanol, n-butanol, isopropanol, or n-propanol; and the third solvent is acetonitrile, tetrahydrofuran, or 1,4-dioxane.

8. A method for preparing a thiacalix[4]aromatic protected copper-silver nanoclusters for electroreduction of CO2 according to any one of claims 2, 5 or 6, characterized in that: The total mass of the copper sulfate pentahydrate, organic silver alkynylene and thiacalix[4] aromatic hydrocarbon is 50 mg to 100 mg, and the total volume of the mixed solvent used is 2 mL to 6 mL.

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