Two-dimensional layered copper fullerene complex material and preparation method and application thereof

Abstract

This invention belongs to the field of coordination polymer technology and discloses a two-dimensional layered copper fullerene complex material, its preparation method, and its application. The chemical formula of this two-dimensional layered copper fullerene complex material is {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2 )2-C 60 ]· x A} n , where n and x Independently selected from non-zero natural numbers, μ3 represents C 60 Coordinated with 3 Cu atoms, η 2 Indicates Cu and C 60 A C=C double bond is coordinated on it; C4H2N2F3 is a 4-trifluoromethylpyrazole anion; C 15 H 12 N6 is 1,3,5-tris(1H-imidazol-1-yl)benzene; A is a guest molecule. The two-dimensional layered copper fullerene complex material provided by this invention exhibits high stability and shows promise for applications in solvent adsorption, electrocatalysis, and other fields. This invention also provides a method for preparing the above-mentioned two-dimensional layered copper fullerene complex material and its applications.

Description

Technical Field

[0001] This invention belongs to the field of coordination polymer technology, specifically relating to a two-dimensional layered copper fullerene complex material, its preparation method, and its application. Background Technology

[0002] As allotropes of carbon, fullerenes, due to their unique size, shape, and physicochemical properties, are conducive to the formation of various ordered functional nanocomplexes; since the first example of a fullerene metal complex (η) was discovered in 1991... 2 -C 60 Since the discovery of Pt(PPh3)2, people have not only been amazed by the special binding ability of fullerenes with transition metals (M), but also delighted by the novel properties and potential applications of the resulting complexes. Subsequently, research on the combination of metals and fullerenes to form fullerene metal complexes has attracted even wider attention.

[0003] Over the past two decades, metal-organic frameworks (MOFs) have seen unprecedented research interest both domestically and internationally. As emerging functional complexes, they have demonstrated promising potential applications in optics, magnetism, electronics, separation, catalysis, and biology. Many scientists have incorporated fullerene molecules into MOF complexes, leveraging the excellent physicochemical properties of both fullerene molecules and MOF complexes to obtain many novel and unique structures and complexes, which has promoted the development of metal-organic frameworks to some extent. However, the lack of strong bonding between fullerene molecules and metal-organic framework structures means that fullerene spheres can only exist in a eutectic or disordered state within the framework's channels. Furthermore, some metal-organic framework structures designed and synthesized using fullerenes as nodes have remained at the structural research stage due to intercalation or insufficient stability. This has significantly limited the study of the properties of fullerene-based metal-organic frameworks and restricted the application of these materials.

[0004] In summary, the poor stability of traditional fullerene metal-organic frameworks limits their applications. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a two-dimensional layered copper fullerene complex material with high stability and broad application prospects in solvent adsorption, electrocatalysis and other fields.

[0006] The present invention also provides a method for preparing the above-mentioned two-dimensional layered copper fullerene complex material.

[0007] This invention also provides applications of the above-mentioned two-dimensional layered copper fullerene complex materials.

[0008] According to an embodiment of the first aspect of the present invention, a two-dimensional layered copper fullerene complex material is provided, wherein the chemical formula of the two-dimensional layered copper fullerene complex material is {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2 )2-C 60 ]·xA} n (Hereafter referred to as Complex 1·xA, or {[Cu6C]) 60 (C 15 H 12 N6)2(C4H2N2F3)6]·xA} n ), where n and x are independently selected from non-zero natural numbers, and μ3 represents C. 60 Three C=C bonds on a six-membered ring in the molecule are simultaneously coordinated with three Cu atoms (specifically, C=C ... 60 (Three C=C bonds on a six-membered ring in the molecule are simultaneously coordinated with three Cu atoms), η 2 Indicates Cu and C 60 One C=C bond is coordinated; C4H2N2F3 represents the 4-trifluoromethylpyrazole anion; C 15 H 12 N6 is 1,3,5-tris(1H-imidazol-1-yl)benzene; A is a guest molecule.

[0009] The two-dimensional layered copper fullerene complex material according to embodiments of the present invention has at least the following beneficial effects: This invention fully utilizes the abundant C=C bonds in fullerene molecules to achieve structural designs in different dimensions. Specifically, fullerene molecules are used as secondary structural units of MOFs, and suitable ligands with strong electronic interaction capabilities and electronic buffering efficiency are selected to complex and bridge with metals, ultimately forming two-dimensional layered copper fullerene complexes with well-defined crystal structures. Due to the selection of ligands and metal ions, coupled with the well-defined crystal structure, the two-dimensional layered copper fullerene complexes provided by this invention can be stably stored in air at room temperature and pressure for more than one month, exhibiting good solvent stability and thermal stability, and possessing high thermal and chemical stability. Furthermore, the two-dimensional layered copper fullerene complexes provided by this invention also possess the ordered porous structure of traditional MOF materials, laying the foundation for their applications in solvent adsorption, electrocatalysis, and other fields.

[0010] Preliminary studies have found that in the two-dimensional layered copper fullerene complex material provided by this invention, C 60There is a host-guest interaction between the copper fullerene complex and the aromatic benzene ring, which gives it a specific recognition and selection effect on benzene in the mixed solution. It can adsorb benzene between the layers of the framework structure, but has no selectivity for cyclohexane. Therefore, the two-dimensional layered copper fullerene complex material can achieve selective adsorption of benzene in the mixture of benzene and cyclohexane.

[0011] According to some embodiments of the present invention, the two-dimensional layered copper fullerene complex material is crystallized in a trigonal crystal system, space group R-3, and is stacked in a two-dimensional layered manner.

[0012] According to some embodiments of the present invention, the two-dimensional layered copper fullerene complex material is crystallized in the triclinic crystal system, space group P-1, and is stacked in a two-dimensional layered manner.

[0013] According to some embodiments of the present invention, in the two-dimensional layered copper fullerene complex material, each Cu atom is coordinated with the N atoms of two 4-trifluoromethylpyrazole anions, and each 4-trifluoromethylpyrazole anion is coordinated with two Cu atoms through two N atoms, forming a trinuclear pyrazole copper coordination unit Cu3(C4H2N2F3)3; the two Cu3(C4H2N2F3)3 units are arranged in Cu-(η 2 The form of the -(C=C)) key is related to C 60 The six C=C bonds (i.e. [6, 6]) on the two six-membered rings at opposite positions of the molecule coordinate to form a hexanuclear pyrazole copper fullerene coordination unit.

[0014] According to some embodiments of the present invention, the three N atoms on the three imidazoles in each 1,3,5-tris(1H-imidazol-1-yl)benzene are respectively coordinated with the Cu atoms on the three hexanuclear pyrazole copper fullerene coordination units to form a two-dimensional bilayer polymer structure based on hexanuclear pyrazole copper fullerene as the basic unit. According to some embodiments of the present invention, guest molecules exist between the layers of the two-dimensional bilayer polymer structure.

[0015] According to some embodiments of the present invention, the guest molecule A includes at least one of toluene and benzene.

[0016] According to some embodiments of the present invention, in the two-dimensional layered copper fullerene complex material, x is any natural number from 6 to 10. For example, it can be any value among 6, 7, 8, 9, and 10.

[0017] According to some embodiments of the present invention, the two-dimensional layered copper fullerene complex material includes Complex 1·8C7H8 (i.e., {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2)2-C 60 ]·8C7H8} n Complex 1·6C6H6 (i.e., {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2 )2-C 60 ]·6C6H6} n ) and Complex 1·10C6H6 (i.e. {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2 )2-C 60 ]·10C6H6} n At least one of the following.

[0018] According to an embodiment of a second aspect of the present invention, a method for preparing the two-dimensional layered copper fullerene complex material described in the first aspect of the present invention is provided, the preparation method comprising the following steps: (1) C 60 Mixed with toluene solvent; (2) Mix the copper source, 4-trifluoromethyl-1H-pyrazole, 1,3,5-tris(1H-imidazol-1-yl)benzene with the mixture obtained in step (1); (3) The mixture obtained in step (2) is subjected to a solvothermal reaction.

[0019] Since the preparation method employs all the technical solutions of the two-dimensional layered copper fullerene complex materials described in the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments. Furthermore, Meanwhile, the preparation method provided by this invention adopts the self-assembly principle and directly utilizes C 60 By exploiting the chemical reactivity of the C=C double bonds on the surface, a two-dimensional layered copper fullerene complex was synthesized in one step via a solvothermal synthesis method using 4-trifluoromethyl-1H-pyrazole as an auxiliary ligand, 1,3,5-tris(1H-imidazol-1-yl)benzene as a bridging ligand, toluene as a solvent, and copper as a source. This preparation method is rapid, convenient, simple, and uses inexpensive raw materials, enabling large-scale production and is beneficial for industrial production and application.

[0020] According to some embodiments of the present invention, in step (1), the C 60The molar volume of the toluene solvent is 0.001~0.004 mmol / mL. For example, it can be 0.001 mmol / mL, 0.002 mmol / mL, 0.003 mmol / mL, 0.004 mmol / mL; or a range of any two of the above values.

[0021] According to some embodiments of the present invention, in step (1), the mixing method is ultrasonic mixing.

[0022] According to some embodiments of the present invention, in step (1), the mixing time is 10 to 30 minutes. For example, it can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes; or a range of values ​​composed of any two of the above point values.

[0023] According to some embodiments of the present invention, in step (2), the copper source includes at least one of cuprous oxide, copper oxide, copper hydroxide and copper nitrate.

[0024] According to some embodiments of the present invention, in the preparation method, the C 60 The molar ratio of 4-trifluoromethyl-1H-pyrazole, 1,3,5-tris(1H-imidazol-1-yl)benzene, and copper source is 1:(10~16):(1~3):(4~8). For example, it can be 1:(12~16):(1.5~2.5):(5~7). More specifically, it can be 1:14:2:6.

[0025] According to some embodiments of the present invention, in step (2), the mixing is carried out under oxygen-free conditions. Specifically, it can be carried out under sealed conditions.

[0026] According to some embodiments of the present invention, in step (3), the temperature of the solvothermal reaction is 160~180℃. For example, it can be 160℃, 165℃, 170℃, 175℃, 180℃; or a range of any two of the above values. Considering that the solvent used is toluene (boiling point 110.6℃), at the above temperature, the pressure generated inside the sealed container of the solvothermal reaction due to the high temperature is much greater than the normal 1 atmosphere, that is, the solvothermal reaction is carried out under high temperature and high pressure conditions. The crystalline coordination polymer prepared by the solvothermal reaction under these conditions has a clear crystal structure, high thermal stability and chemical stability.

[0027] According to some embodiments of the present invention, in step (3), the holding time for the solvothermal reaction is 48 to 72 hours. For example, it can be 48 hours, 50 hours, 52 hours, 54 hours, 56 hours, 58 hours, 60 hours, 62 hours, 64 hours, 66 hours, 68 hours, 70 hours, or 72 hours; or a range of values ​​composed of any two of the above points.

[0028] According to some embodiments of the present invention, in step (3), the cooling rate of the solvothermal reaction is 3~10℃ / h. Specifically, it can be 3℃ / h, 4℃ / h, 5℃ / h, 6℃ / h, 7℃ / h, 8℃ / h, 9℃ / h, 10℃ / h; or a range of any two of the above values. To avoid burns during operation, subsequent operations should be performed after the temperature has dropped to room temperature.

[0029] According to some embodiments of the present invention, in step (3), the solvothermal reaction is carried out under closed conditions.

[0030] According to some embodiments of the present invention, step (3) further includes washing and drying the solid product obtained by the solvothermal reaction after the solvothermal reaction. The solvents used for cleaning include aromatic solvents.

[0031] The aromatic solvent is selected from at least one of benzene, toluene, and p-xylene.

[0032] According to some embodiments of the present invention, the preparation method further includes a solvent exchange step performed after step (3).

[0033] According to some embodiments of the present invention, the solvent selected for the solvent exchange includes at least one of benzene and cyclohexane.

[0034] According to some embodiments of the present invention, the solvent used for solvent exchange is benzene.

[0035] According to some embodiments of the present invention, the solvent used for solvent exchange is a mixture of benzene and cyclohexane. The volume ratio of benzene to cyclohexane is (1:1) to (1:10). Specifically, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10; or a range of values ​​consisting of any two of the above points.

[0036] According to some embodiments of the present invention, the specific operation of the solvent exchange includes immersing the product obtained in step (3) in the solvent and allowing it to stand in a closed environment. The standing time is 6 to 7 days. The standing conditions are room temperature and normal pressure. When the solvent used includes benzene, the two-dimensional layered copper fullerene complex material is Complex 1·6C6H6.

[0037] According to some embodiments of the present invention, the specific operation of the solvent exchange includes immersing the product obtained in step (3) in the solvent and allowing it to stand in a closed environment. The standing time is 8-12 hours. The standing condition is pressurization. The pressurization pressure is 0.15-0.4 MPa; for example, it can be 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa; or a range of any two of the above values. When the solvent used includes benzene, the two-dimensional layered copper fullerene complex material is Complex 1·10C6H6.

[0038] According to an embodiment of a third aspect of the present invention, an application of the two-dimensional layered copper fullerene complex material described in the first aspect of the present invention in benzene extraction is provided.

[0039] Since the application adopts all the technical solutions of the two-dimensional layered copper fullerene complex material of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0040] According to some embodiments of the present invention, the benzene extraction is performed on a pure benzene system or a mixture of benzene and cyclohexane. In the mixture of benzene and cyclohexane, the volume ratio of benzene to cyclohexane is (1:1) to (1:10). Specifically, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10; or a range of values ​​consisting of any two of the above points. In the listed systems, the two-dimensional layered copper fullerene complex material can selectively recognize and adsorb benzene molecules.

[0041] According to an embodiment of a fourth aspect of the present invention, a method for preparing a two-dimensional layered copper fullerene complex composite material is provided, the method comprising the following steps: S1. Calcining the two-dimensional layered copper fullerene complex material described in the first aspect embodiment of the present invention in an inert atmosphere; S2. After mixing the roasted product obtained in step S1 with copper salt, roast it again in an inert atmosphere.

[0042] Since the method adopts all the technical solutions of the two-dimensional layered copper fullerene complex material of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0043] According to some embodiments of the present invention, in step S1, the calcination temperature is 120~170℃. Specifically, it can be 120℃, 130℃, 140℃, 150℃, 160℃, or 170℃; or a range consisting of any two of the above values. During calcination, the heating rate has almost no effect on the product performance, and the present invention does not impose strict limitations on it.

[0044] According to some embodiments of the present invention, in step S1, the roasting time is 1 to 4 hours. For example, it can be 1 hour, 2 hours, 3 hours, 4 hours; or a range of values ​​composed of any two of the above points.

[0045] According to some embodiments of the present invention, the calcination product obtained in step S1 is a black powder.

[0046] According to some embodiments of the present invention, the mixing method in step S2 is grinding. The grinding apparatus includes an agate mortar.

[0047] According to some embodiments of the present invention, in step S2, the copper salt is at least one of cuprous thiocyanate, copper trifluoroacetate, and copper nitrate trihydrate.

[0048] According to some embodiments of the present invention, in step S2, the mass percentage of copper in the added copper salt in the mixture is 10-50%. For example, it can be 10%, 20%, 30%, 40%, 45%, 50%; or a range of values ​​composed of any two of the above points.

[0049] According to some embodiments of the present invention, in step S2, the temperature of the second roasting is 350~550℃. For example, it can be 350℃, 400℃, 450℃, 500℃, 550℃; or a range of values ​​composed of any two of the above points.

[0050] In the re-calcination process, the heating rate has almost no effect on the product performance, and the present invention does not impose strict limitations on it.

[0051] According to some embodiments of the present invention, in step S2, the duration of the re-roasting is 1 to 4 hours. For example, it can be 1 hour, 2 hours, 3 hours, or 4 hours; or a range of values ​​composed of any two of the above points.

[0052] According to some embodiments of the present invention, the inert atmosphere in steps S1 and S2 is independently selected from at least one of nitrogen (N2), helium (He) and argon (Ar).

[0053] According to an embodiment of the fifth aspect of the present invention, a two-dimensional layered copper fullerene complex composite material prepared by the method described in the fourth aspect of the present invention is provided.

[0054] Since the two-dimensional layered copper fullerene complex composite material adopts all the technical solutions of the methods in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0055] According to some embodiments of the present invention, the two-dimensional layered copper fullerene complex composite material is in the form of a brown powder.

[0056] According to an embodiment of the sixth aspect of the present invention, an application of the two-dimensional layered copper fullerene complex composite material described in the fifth aspect of the present invention in electrocatalytic CO2 reduction is provided.

[0057] Since the application employs all the technical solutions of the two-dimensional layered copper fullerene complex composite material of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments. Furthermore, Due to the non-renewable nature of fossil fuels and the energy crisis and greenhouse effect caused by their overuse, the reduction of CO2 into high-value chemical products and fuels has become an important solution. Among these solutions, electrocatalytic conversion technology has attracted much attention because it can directly utilize renewable energy electricity and clean water. Copper-based coordination compound materials have received widespread attention in this field due to their unique structure and tunable pore size / channel structure. However, traditional copper-based catalysts still face problems such as insufficient CO2 adsorption and activation capacity, low charge transfer efficiency, insufficient selectivity for multi-carbon products, and poor long-term stability.

[0058] When used as a catalyst for electrocatalytic CO2 reduction, the two-dimensional layered copper fullerene complex composite material of the present invention exhibits excellent electrocatalytic activity and selectivity. At the optimal potential of -1.2V (vs. RHE), the Faraday efficiency of C2H5OH is 62.3%, and the Faraday efficiency of C2 products (i.e., the sum of C2H4 and C2H5OH) is 75.7%, effectively enhancing the selectivity of high-value C2 products. Simultaneously, the two-dimensional layered copper fullerene complex composite material possesses excellent chemical stability; it is not easily oxidized in air; and its catalytic performance is stable.

[0059] According to some embodiments of the present invention, in the application of electrocatalytic CO2 reduction, the two-dimensional layered copper fullerene complex composite material is attached to the surface of the working electrode as an electrocatalyst. The method for preparing the working electrode includes dispersing the two-dimensional layered copper fullerene complex composite material in a mixed solvent of ethanol and 5% Nafion to obtain a slurry, and then coating the obtained slurry onto the surface of a glassy carbon electrode.

[0060] In the mixed solvent, the volume ratio of ethanol to 5% Nafion is (94~99):(6~1); for example, it can be 94:6, 94:3, 94:1, 99:6, 99:3, 99:1; or a range of values ​​consisting of any two of the above points.

[0061] In the slurry, the mass-to-volume ratio of the two-dimensional layered copper fullerene complex composite material to the mixed solvent is (1.5~2.5) mg: 1 mL.

[0062] In the working electrode, the loading of the two-dimensional layered copper fullerene complex composite material is 0.1~0.5 mg / cm³. 2 For example, it could be 0.1 mg / cm³. 2 0.2 mg / cm 2 0.3 mg / cm 2 0.4 mg / cm 2 0.5 mg / cm 2 ; or the range of values ​​formed by any two of the above point values.

[0063] According to some embodiments of the present invention, in the application of electrocatalytic CO2 reduction, the electrolyte is a CO2-saturated KHCO3 solution. The concentration of the KHCO3 solution is 0.05~0.15 mol / L. For example, it can be 0.1 mol / L.

[0064] According to some embodiments of the present invention, the method used in the electrocatalytic CO2 reduction application is the chronoamperometry method. The voltage used is -1.0V to -1.4V. Specifically, it can be -1.0V, -1.1V, -1.2V, -1.3V, -1.4V; or a range consisting of any two of the above values.

[0065] According to some embodiments of the present invention, in electrocatalytic CO2 reduction, the two-dimensional layered copper fullerene complex composite material exhibits a C2H5OH Faradaic efficiency ≥60% and a C2 (i.e., the sum of C2H4 and C2H5OH) Faradaic efficiency ≥75% at -1.2V (vs. RHE).

[0066] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0067] Figure 1 These are powder X-ray diffraction (PXRD) spectra of the two-dimensional layered copper fullerene complex materials obtained in Examples 1-3 of this invention; wherein (a) Complex 1.8C7H8, (b) Complex 1.6C6H6, and (c) Complex 1.10C6H6; Figure 2 This is the Fourier transform infrared (FT-IR) spectrum of the two-dimensional layered copper fullerene complex material of Example 1 of the present invention; Figure 3 This is the solid-state ultraviolet-visible-near-infrared (UV-VIS-NIR) absorption spectrum of the two-dimensional layered copper fullerene complex material of Example 1 of the present invention; Figure 4These are the thermogravimetric analysis (TGA) spectra of the two-dimensional layered copper fullerene complex materials of Examples 1-3 of the present invention, wherein (a) Complex 1.8C7H8, (b) Complex 1.6C6H6, and (c) Complex 1.10C6H6; Figure 5 This is a two-dimensional layered structure diagram of the two-dimensional layered copper fullerene complex material of Embodiment 1 of the present invention along the crystallographic ab plane and c axis direction; Figure 6 This is a transmission electron microscope (TEM) image of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 of the present invention; Figure 7 These are solid Raman images of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 of this invention and the copper fullerene derivative material prepared in Comparative Example 1. Figure 8 These are the X-ray absorption (XPS) spectra of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 of this invention and the copper fullerene derivative material prepared in Comparative Example 1. Figure 9 The linear current-voltage (LSV) curves of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 of this invention and the copper fullerene derivative material prepared in Comparative Example 1 are shown. Figure 10 This is a stability test diagram of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 of the present invention.

[0068] Figure 11 This is a schematic diagram of the solvent exchange mechanism in Example 4 of the present invention. Detailed Implementation

[0069] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; and all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0070] Example 1 This example provides a two-dimensional layered copper fullerene complex material and its preparation method. The specific steps of the preparation method are as follows: (1) Weigh 0.005 mmol C 60 Dissolve it in 2.4 mL of toluene and sonicate it for 10 minutes. (2) Weigh 0.07 mmol of 4-trifluoromethyl-1H-pyrazole (CAS: 52222-73-8), 0.01 mmol of 1,3,5-tris(1H-imidazol-1-yl)benzene (CAS: 528543-96-6), and 0.03 mmol of cuprous oxide (CAS: 1317-39-1) and place them in an 8×12 mm hard glass tube. Mix them with the mixture obtained in step (1). Seal the glass tube opening with a water welding machine (hydrogen-oxygen machine) and put it into a stainless steel iron box. (3) After sealing the equipment in step (2), heat it to 180°C in an oven and keep it at a constant temperature for 72 hours. Then, cool it to room temperature at a rate of 5°C / h. After filtering with an open tube, clean it with toluene and dry it naturally at room temperature to obtain Complex 1·8C7H8.

[0071] Based on this example, other variations or modifications can be made. For example, in C described in this invention... 60 The molar ratio of 4-trifluoromethyl-1H-pyrazole and 1,3,5-tris(1H-imidazol-1-yl)benzene and cuprous oxide; C 60 By varying the molar volume in toluene solvent, the temperature, holding time, and cooling rate of the solvothermal reaction, etc., within the range provided by this invention, two-dimensional layered copper fullerene complex materials with similar structural effects to those in Example 1 can also be prepared.

[0072] Example 2 This example provides a two-dimensional layered copper fullerene complex material and its preparation method. The specific steps of the preparation method differ from those in Example 1 in that: Following step (3) of Example 1, the following step is added: (4) Take 10 mg of Complex 1·8C7H8 from Example 1 and immerse it in benzene solvent at room temperature and pressure. Place it in a glove box under dry N2 atmosphere and seal it for one week. Take out the crystals, filter them, and dry them naturally to obtain Complex 1·6C6H6.

[0073] Example 3 This example provides a two-dimensional layered copper fullerene complex material and its preparation method. The specific steps of the preparation method differ from those in Example 1 in that: Following step (3) of Example 1, the following step is added: (4) Take 10 mg of Complex 1·8C7H8 from Example 1 and soak it in an open reagent bottle containing 1 mL of benzene. Place the bottle in a high-pressure reactor with 0.2 MPa nitrogen gas introduced at room temperature and let it stand for 10 hours. Then open the reactor, take out the crystals, filter them, and let them dry naturally to obtain Complex 1·10C6H6.

[0074] Example 4 This example provides a two-dimensional layered copper fullerene complex material and its preparation method. The specific steps of the preparation method differ from those in Example 2 in that: In step (4), the pure benzene solvent is replaced with a mixed solvent of benzene and cyclohexane in volume ratios of 1:1, 1:5 and 1:10.

[0075] The resulting products were named Complex 1·6C6H6-1, Complex 1·6C6H6-5, and Complex 1·6C6H6-10, respectively.

[0076] The mechanism in this example is as follows: Figure 11 As shown, in the mixed system of benzene and cyclohexane, the product obtained in Example 1 can still selectively recognize and adsorb benzene.

[0077] Example 5 This example provides a two-dimensional layered copper fullerene complex composite material and a method for preparing the two-dimensional layered copper fullerene complex composite material. The specific steps of the method are as follows: S1. Take 150 mg of Complex 1·8C7H8 from Example 1 and heat it to 150°C in a tube furnace under an argon atmosphere at a heating rate of 5°C / min. Hold the temperature for 2 hours and then allow it to cool naturally to room temperature to obtain a black powder. S2. Weigh 42mg of the above black powder and 34.45mg of cuprous thiocyanate (CAS: 1111-67-7) into a natural agate mortar and grind them evenly for 5 minutes to obtain a yellow powder. The yellow powder was placed in a tube furnace and heated to 450°C at a heating rate of 5°C / min under an argon atmosphere. After holding the temperature for 2 hours, it was naturally cooled to room temperature to obtain the final product, a brown powder, which is a two-dimensional layered copper fullerene complex composite material.

[0078] Comparative Example 1 This example provides a copper fullerene-derived material, and the specific preparation method is as follows: Weigh 100 mg of the product obtained in step S1 of Example 5 and heat it to 450°C in a tube furnace under an argon atmosphere at a heating rate of 5°C / min. After holding the temperature for 2 hours, allow it to cool naturally to room temperature to obtain a black powder.

[0079] Application examples In this example, the two materials obtained in Example 5 and Comparative Example 1 were used as catalysts to carry out the electrocatalytic reduction of CO2; the specific steps are as follows: Take 2 mg of the two-dimensional layered copper fullerene complex composite material obtained in Example 5 or the copper fullerene derivative material obtained in Comparative Example 1 and disperse it in 1 mL of a mixed solution of ethanol and 5% Nafion (ethanol: 5% Nafion = 99: 1). Disperse it ultrasonically for 15 minutes. Take 100 μL of the resulting slurry and drop it onto a columnar glassy carbon electrode (glassy carbon diameter is 1 cm, partially coated, and the reaction area is precisely controlled) wrapped with PTFE. Let it dry at room temperature and use it as the working electrode. Use Ag / AgCl as the reference electrode and a carbon rod as the counter electrode.

[0080] Electrocatalytic performance was tested using chronoamperometry in a CO2-saturated 0.1 mol / L KHCO3 solution (as electrolyte); the test voltage range for electrocatalytic reduction was -1.0 V (vs. RHE) to -1.4 V (vs. RHE).

[0081] Test case The first aspect of this example characterizes the crystal structure of the products obtained in Examples 1-4. The specific characterization method is as follows: Suitable complexes prepared in the examples were selected under an optical microscope and placed on a Rigaku XtaLAB single-crystal diffractometer (operating at 25kW power: 45kV, 40mA). Cu Kα radiation (λ=1.5418) was used to scan in ω / θ mode, and diffraction data were collected at low temperature (100K). The test results also showed that the crystal data of the three products in Examples 2 and 4 were completely consistent. Therefore, subsequent molecular analysis was only based on the results of the products obtained in Examples 1 to 3.

[0082] The data results were analyzed using the direct method (SHELXTL-2018) and the least multiplication method of the entire matrix was applied. F 2 The coordinates and anisotropy parameters of all non-hydrogen atoms were obtained through fine-tuning. The specific crystal data are shown in Table 1. Table 1. Crystallographic parameters of the two-dimensional layered copper fullerene complexes obtained in Examples 1-3

[0083] Table 1 a R1 = ∑(||F o | - |F c ||) / ∑|F o |; b wR2=[∑w(F o 2 - F c 2 ) 2 / ∑w(F o 2 ) 2 ] 1 / 2.

[0084] As shown in Table 1, the two-dimensional layered copper fullerene complex materials prepared in the examples possess a two-dimensional layered structure. The chemical formula of the complex Complex 1·8C7H8 is {[Cu6(C 60 (C) 15 H 12 N6)2(C4H2N2F3)6] . 8C7H8} n Where n is a non-zero natural number, and the complex crystal belongs to the trigonal crystal system, space group R-3. C4H2N2F3 represents the deprotonated 4-trifluoromethylpyrazole anion ligand, C... 15 H 12 N6 represents the bridging ligand 1,3,5-tris(1H-imidazol-1-yl)benzene, and C7H8 represents the guest molecule toluene; the difference between Complex 1·6C6H6 and Complex 1·10C6H6 lies only in the difference in the guest molecule and the resulting difference in symmetry (space group).

[0085] based on Figure 1 The data results represent the plotting of the crystal structure of the complex 1·8C7H8 as follows: Figure 5 As shown. Among them, Figure 5 Figure (a) is a two-dimensional structure diagram along the crystallographic ab plane; Figure 5 Figure (b) is a two-dimensional structural diagram along the c-axis. Although the guest molecules in the products obtained in Examples 2 and 3 are different, the packing arrangement remains unchanged; for clarity, Figure 5 Hidden within is a hydrogen atom and a trifluoromethyl group on 4-trifluoromethylpyrazole. From Figure 5 It can be seen that the copper atoms in Complex 1·8C7H8 adopt a four-coordinate configuration, with each copper atom coordinated to the N atoms of two 4-trifluoromethylpyrazoles, and then coordinating with Cu-(η) 2 The form of the -(C=C)) key is related to C 60 Coordination, the fourth coordination site connects to the N atom on the imidazole in 1,3,5-tris(1H-imidazol-1-yl)benzene. Each C 60The molecule coordinates with six Cu(I) atoms through six C=C bonds on two six-membered rings at opposite ends, forming a hexanuclear pyrazole copper fullerene coordination unit. 1,3,5-tris(1H-imidazol-1-yl)benzene coordinates with copper atoms on this hexanuclear pyrazole copper fullerene coordination unit via the N atom on the imidazolium atom, forming a two-dimensional layered polymer structure based on the hexanuclear pyrazole copper fullerene as the basic unit. Toluene guest molecules exist in the interlayer spaces. The resulting Complex 1·8C7H8 is characterized by six Cu atoms bridged by six 4-trifluoromethylpyrazole atoms and two 1,3,5-tris(1H-imidazol-1-yl)benzene atoms, forming a porous metal-organic framework with the fullerene pyrazole copper unit as the building block.

[0086] Furthermore, this example also tested the powder X-ray diffraction (PXRD) spectra of the products obtained in the examples using powder X-ray diffraction (PXRD); the test results are as follows. Figure 1 As shown, the test results of the product obtained in Example 1 are as follows: Figure 1 As shown in Figure (a), the test results of the product obtained in Example 2 are as follows. Figure 1 As shown in Figure (b), the test results of the product obtained in Example 3 are as follows. Figure 1 As shown in Figure (c). From Figure 1 It can be seen that the crystal phase of the two-dimensional layered copper fullerene complex material obtained in the examples matches the simulated powder, and has good crystal phase purity. Figure 1 The simulated powder is obtained by simulating the crystal structure data obtained by single-crystal diffraction using software. Each peak of the tested powder represents a crystal plane of the crystal structure. If the actual measured powder diffraction matches the single-crystal diffraction well, it indicates that the obtained material has good crystal phase purity and no other impurities.

[0087] The second aspect of this example tested the Fourier transform infrared (FT-IR), ultraviolet-visible-near-infrared absorption spectra (UV-Vis), and thermogravimetric analysis of the products obtained in the examples and comparative examples. Specific test results are as follows: Figures 2-4 As shown. Specifically: Figure 2 The Fourier transform infrared (FT-IR) spectrum of the product obtained in Example 1 shows the presence of C. 60 The N=N and CF characteristic peaks on 4-trifluoromethylpyrazole further confirm that the target two-dimensional layered copper fullerene complex material has been successfully synthesized.

[0088] Figure 3 The solid ultraviolet-visible-near-infrared (UV-VIS-NIR) absorption spectrum of the product obtained in Example 1 of this invention shows that the complex has strong absorption in the entire ultraviolet-visible-near-infrared region.

[0089] Figure 4 The thermogravimetric analysis (TGA) diagrams of the products obtained in the examples are shown, where (a) corresponds to Example 1, (b) corresponds to Example 2, and (c) corresponds to Example 3. The results show that Complex 1·8C7H8 begins to lose guest toluene molecules after 100°C, eventually losing approximately 21.2%. Complex 1·6C6H6 begins to lose guest benzene molecules when the temperature rises to 90°C, eventually losing 12.1% of the guest benzene molecules. Complex 1·10C6H6 begins to lose guest benzene molecules when the temperature rises to 90°C, losing 22.3% at 243°C. Figure 4 The results show that the weightlessness platform of the object in the products of Examples 1 to 3 is basically consistent with the theoretical calculation.

[0090] The third aspect of this example tested the TEM image of the product obtained in Example 5, the solid-state Raman spectroscopy of the products obtained in Example 5 and Comparative Example 1, and their X-ray absorption (XPS) spectra; the specific test results are as follows: Figures 6-8 As shown.

[0091] from Figure 6 As can be seen from the example, the two-dimensional layered copper fullerene complex composite material obtained in Example 5 has a two-dimensional layered structure. Figure 7 The results show that graphitization occurred in the products obtained in both Example 5 and Comparative Example 1. This may be due to C 60 The formation of polymers. Figure 8 High-resolution Cu2p orbital diagrams (a) and CuLMM Auger electron spectra (b) of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 and the copper fullerene material prepared in Comparative Example 1 are shown. Figure 8 The results show that the +1 valence peak of Cu dominates in both the two-dimensional layered copper fullerene complex composite material and the copper fullerene derivative material. Data comparison shows that the materials prepared in Example 5 and Comparative Example 1 can stabilize the valence state of Cu and enhance the product selectivity in CO2 reduction.

[0092] In the fourth aspect of this example, the reduction effect of carbon dioxide in the application example was tested. Specifically, gas chromatography and nuclear magnetic resonance spectroscopy were used to analyze the gaseous and liquid products obtained from the reduction in the application example. Since all guest molecules escape under calcination conditions at 450°C, there is objectively no difference between the two-dimensional layered copper fullerene complex composite materials prepared in Examples 1-4. Therefore, the product obtained in Example 5 is used as an example here. The Faradaic efficiency of the product obtained in Example 5 is shown in Table 2, and the Faradaic efficiency of the product in Comparative Example 1 is shown in Table 3. The overall test results of Example 5 and Comparative Example 1 are as follows: Figure 9 As shown; the stability test results of the product obtained in Example 5 are as follows. Figure 10 As shown.

[0093] Table 2. Electrocatalytic performance test results of the two-dimensional layered copper fullerene complex composite material obtained in Example 5. Voltage <![CDATA[Faradaic efficiency of C2H5OH]]> <![CDATA[C2 Faradaic efficiency]]> -1.0V (vs. RHE) 56.1 57.5 -1.1V (vs. RHE) 55.4 67.7 -1.2V (vs. RHE) 62.3 75.7 -1.3V (vs. RHE) 57.5 71.5 -1.4V (vs. RHE) 51.1 67.2 Table 3 Electrocatalytic performance test results of the product obtained in Comparative Example 1 Voltage <![CDATA[C2H5OH Faradaic efficiency]]> <![CDATA[C2 Faradaic efficiency]]> -1.0V (vs. RHE) 11.3 27.9 -1.1V (vs. RHE) 13.4 23.9 -1.2V (vs. RHE) 15.7 24.5 -1.3V (vs. RHE) 11.3 19.3 -1.4V (vs. RHE) 13.1 20.2 Figure 9 The current densities obtained by LSV testing in CO2 and N2 for the derived materials obtained in Example 5 and Comparative Example 1 are shown using dotted and line graphs of different shapes. (Tables 2-3 and...) Figure 9 The data shows that the current density of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 is higher in a CO2 atmosphere than in an N2 atmosphere, indicating that its CO2 reduction Faradaic efficiency is higher than its hydrogen evolution reaction Faradaic efficiency. Simultaneously, in the same CO2 atmosphere, the current density of the two-dimensional layered copper fullerene complex composite material prepared in Example 5 is higher than that of the copper fullerene derivative material prepared in Comparative Example 1. This indicates that the two-dimensional layered copper fullerene complex composite material prepared in Example 5 has a higher CO2 reduction Faradaic efficiency and better CO2 reduction selectivity in the electrolyte. Furthermore, we conducted stability tests using the chronoamperometry at -1.2V (vs. RHE). Figure 10 It can be seen that the product obtained in Example 5 has good long-term current stability and product selectivity.

[0094] Overall, compared with the copper fullerene derivative material directly prepared from the two-dimensional layered copper fullerene complex material (Comparative Example 1), the two-dimensional layered copper fullerene complex composite material obtained in Example 5 exhibits high electrocatalytic activity and good C2 product selectivity. At the optimal potential of -1.2V (vs. RHE), the C2H5OH Faradaic efficiency is 62.3%, and the C2 (i.e., the sum of C2H4 and C2H5OH) Faradaic efficiency is 75.7%, effectively enhancing the selectivity for high-value products. This two-dimensional layered copper fullerene complex composite material also exhibits excellent chemical stability. It is not easily oxidized in air, and its catalytic performance is stable.

[0095] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A two-dimensional layered copper fullerene complex material, characterized in that, The chemical formula of the two-dimensional layered copper fullerene complex material is {[Cu3(C4H2N2F3)3(C 15 H 12 N6)]2[(μ3-η 2 :η 2 :η 2 )2-C 60 ]·xA} n Where n and x are independently selected from non-zero natural numbers, and μ3 represents C. 60 Coordinated with 3 Cu atoms, η 2 Indicates Cu and C 60 A C=C double bond is coordinated on it; C4H2N2F3 represents the 4-trifluoromethylpyrazole anion; C 15 H 12 N6 is 1,3,5-tris(1H-imidazol-1-yl)benzene; A is a guest molecule.

2. The two-dimensional layered copper fullerene complex material according to claim 1, characterized in that, The two-dimensional layered copper fullerene complex material is crystallized in the trigonal crystal system, space group R-3, and is stacked in a two-dimensional layered manner; or, the two-dimensional layered copper fullerene complex material is crystallized in the triclinic crystal system, space group P-1, and is stacked in a two-dimensional layered manner.

3. The two-dimensional layered copper fullerene complex material according to claim 1, characterized in that, In the two-dimensional layered copper fullerene complex material, each Cu atom is coordinated with the N atoms of two 4-trifluoromethylpyrazole anions, and each 4-trifluoromethylpyrazole anion is coordinated with two Cu atoms through two N atoms, forming a trinuclear pyrazole copper coordination unit Cu3(C4H2N2F3)3; the two Cu3(C4H2N2F3)3 units are arranged in Cu-(η 2 The form of the -(C=C)) key is related to C 60 The six C=C bonds on the two six-membered rings at opposite positions in the molecule coordinate to form a hexanuclear pyrazole copper fullerene coordination unit; Preferably, the three N atoms on the three imidazoles in each 1,3,5-tris(1H-imidazol-1-yl)benzene are respectively coordinated with the Cu atoms on the three hexanuclear pyrazole copper fullerene coordination units to form a two-dimensional bilayer polymer structure based on hexanuclear pyrazole copper fullerene as the basic unit. Preferably, the two-dimensional bilayer polymer structure contains guest molecules.

4. The two-dimensional layered copper fullerene complex material according to any one of claims 1 to 3, characterized in that, The guest molecule A includes at least one of benzene and toluene; Preferably, in the two-dimensional layered copper fullerene complex material, x is any natural number from 6 to 10.

5. A method for preparing a two-dimensional layered copper fullerene complex material as described in any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: (1) C 60 Mixed with toluene solvent; (2) Mix the copper source, 4-trifluoromethyl-1H-pyrazole, 1,3,5-tris(1H-imidazol-1-yl)benzene with the mixture obtained in step (1); (3) The mixture obtained in step (2) is subjected to a solvothermal reaction.

6. The preparation method according to claim 5, characterized in that, In step (2), the copper source includes at least one of cuprous oxide, copper hydroxide, copper oxide, and copper nitrate; Preferably, in step (3), the temperature of the solvothermal reaction is 160~180℃; Preferably, in step (3), the holding time for the solvothermal reaction is 48 to 72 hours; Preferably, the preparation method further includes a solvent exchange step performed after step (3); Preferably, the solvent used for solvent exchange includes at least one of benzene and toluene.

7. The application of a two-dimensional layered copper fullerene complex material as described in any one of claims 1 to 4 in benzene extraction.

8. A method for preparing two-dimensional layered copper fullerene complex composite materials, characterized in that, The method includes the following steps: S1. Calcining the two-dimensional layered copper fullerene complex material according to any one of claims 1 to 4 in an inert atmosphere; S2. After mixing the roasted product obtained in step S1 with copper salt, roast it again in an inert atmosphere.

9. A two-dimensional layered copper fullerene complex composite material prepared by the method described in claim 8.

10. The application of the two-dimensional layered copper fullerene complex composite material as described in claim 9 in electrocatalytic CO2 reduction.

Images