Copper nanocluster and preparation method and application thereof

Abstract

The invention discloses a copper nanocluster and a preparation method and application thereof, the molecular formula of the copper nanocluster is Cu45H6X18Y15, X is a dehydrogenated alkyne ligand, and Y represents a dehydrogenated acid ligand. The copper nanocluster is a 6-electron super-atom copper nanocluster Cu45, a Cu < + > / Cu0 interface is introduced, and the copper nanocluster has acid, alkali, heat and long-term stability, so that the copper nanocluster can be applied to electrocatalytic CO2 reduction reaction.

Description

Technical Field

[0001] The present application relates to the technical field of nanomaterials, and in particular, to a copper nanocluster and a preparation method and application thereof. Background Art

[0002] Atomically precise metal nanoclusters (NCs) usually have a metal core smaller than 3 nanometers, and exhibit unique physical and chemical properties due to size effects and quantum confinement effects. These nanoclusters have become important research targets in the fields of catalysis, biomedicine, and clean energy due to their precise structures and good monodispersity. In particular, in the field of catalysis, thanks to their soluble crystal structures, these nanoclusters provide valuable insights into the structure-function relationship in catalytic processes.

[0003] Gold and silver metal nanoclusters have been widely studied and applied, but copper-based metal nanoclusters (Cu NCs) have always faced great challenges in synthesis and stability due to their easy oxidation and instability. The M(I) / M(0) reduction potential of copper is 0.52V, which is significantly lower than that of silver (0.80V) and gold (1.69V). This makes copper-based nanoclusters very easy to oxidize in the air, which in turn affects their synthesis and subsequent applications. The oxidative instability and low reduction potential of copper make nanoclusters containing Cu(0) often highly sensitive to the external environment, which brings great difficulties to their application in the fields of catalysis and energy. Copper is the only known metal that can efficiently catalyze CO 2 (CO 2 RR) is a metal that is electrocatalytically reduced to polycarbonate compounds.

[0004] Therefore, further research is needed on copper nanoclusters. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art to a certain extent. To this end, the present application provides a copper nanocluster, which has acid, alkali, thermal and long-term stability, and introduces Cu + / Cu 0 interface.

[0006] In the first aspect of the present application, the present application proposes a copper nanocluster, wherein the molecular formula of the copper nanocluster is Cu 45 H 6 X 18 Y 15 , wherein X is a dehydrogenated alkyne ligand and Y represents a dehydrogenated acid ligand. Thus, the copper nanocluster is a 6-electron superatomic copper nanocluster Cu 45 , Cu + / Cu 0 interface, with acid, base, thermal, and long-term stability, making it applicable to electrocatalytic CO2 In the reduction reaction.

[0007] According to an embodiment of the present application, the acid ligand includes acetic acid.

[0008] According to an embodiment of the present application, the alkyne ligand includes at least one alkyne compound with the general formula Z-C≡CH, where Z is a substituted or unsubstituted phenyl group, and the substituents of the phenyl group include at least one of trifluoromethyl, methyl, methoxy, fluorine, chlorine, bromine, and iodine.

[0009] According to an embodiment of the present application, the molecular formula of the copper nanocluster is Cu 45 H 6 (C≡C-C 6 H 3 -3,5-(CF 3 ) 2 ) 18 (CH 3 COO) 15 .

[0010] According to an embodiment of the present application, the core of the copper nanocluster is composed of 45 Cu atoms, and the center is a double-capped icosahedron Cu 15 , and the double-capped icosahedron is surrounded by a Cu 2 shell layer composed of Cu 30 units bridged by 15 acid ligands, and 18 alkyne ligands are hierarchically arranged in 6 layers along the C 3 axis of the core;

[0011] Optionally, the alkyne ligand adopts μ 4 -η 1 ,η 1 ,η 1 , η 2 , μ 3 -η 1 ,η 2 ,η 2 , μ 5 -η 1 ,η 1 ,η 1 ,η 2 ,η 2 three coordination modes;

[0012] Optionally, the acid ligand adopts μ 2 -η 1 ,η 1 coordination mode;

[0013] Optionally, the copper nanocluster has D 3 symmetry.

[0014] In the second aspect of the present application, a method for preparing the above-mentioned copper nanoclusters is proposed, including the following steps:

[0015] (1) Mix a copper precursor, an alkyne ligand, an acid ligand, and a first solvent to obtain a first solution;

[0016] (2) Mix the first solution with a base to obtain a second solution;

[0017] (3) Mix the second solution with a reducing agent to carry out a reduction reaction to obtain the copper nanoclusters.

[0018] According to an embodiment of the present application, the copper precursor includes Cu(CH 3 CN) 4 A, where A represents an anion, and the anion is F - 、Cl - 、Br - 、ClO 4 - 、PF 6 - 、OTf - 、BF 4 、SbF 6 、NO 3 、CH 3 COO、CF 3 SO 3 at least one of them.

[0019] According to an embodiment of the present application, the molar ratio of the amounts of the copper precursor, the alkyne ligand, and the acid ligand is 10:(3 - 7):(4 - 8).

[0020] According to an embodiment of the present application, in the first solution, the amount of the first solvent is such that the concentration of the copper precursor in the first solution is 0.01 - 0.3 mol / L.

[0021] According to an embodiment of the present application, the first solvent includes dichloromethane and methanol.

[0022] According to an embodiment of the present application, the base includes triethylamine.

[0023] According to an embodiment of the present application, relative to the amount of 1 mol of the copper precursor, the amount of the base is 0.5 - 1 mol.

[0024] According to an embodiment of the present application, the reducing agent includes diphenylsilane.

[0025] According to an embodiment of the present application, step (3) includes: adding the reducing agent to the second solution in batches, and the amount added each time accounts for 10% - 70% of the total amount of the reducing agent.

[0026] According to an embodiment of the present application, relative to 1 mol of the copper precursor, the amount of the reducing agent used is 0.5 to 2 mol.

[0027] According to an embodiment of the present application, the temperature of the reduction reaction is 10 to 40 °C, and the time is 6 to 72 h.

[0028] According to an embodiment of the present application, in step (1), the mixing is carried out under stirring conditions, and the stirring time is 5 to 10 min.

[0029] According to an embodiment of the present application, in step (2), the mixing is carried out under stirring conditions, and the stirring time is 10 to 20 min.

[0030] In the third aspect of the present application, the present application proposes the above-mentioned copper nanoclusters in electrocatalytic CO 2 reduction reaction.

[0031] The additional aspects and advantages of the present application will be partly given in the following description, partly become obvious from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0033] Figure 1 is a schematic diagram of the single crystal structure of the copper nanoclusters in Example 2 of the present application;

[0034] Figure 2 is a schematic diagram of the metal core structure of the copper nanoclusters in Example 2 of the present application;

[0035] Figure 3 is a mass spectrometry data diagram of the copper nanoclusters in Example 2 of the present application;

[0036] Figure 4 is a diagram of the absorption spectrum and TD-DFT calculation results of the copper nanoclusters in Example 2 of the present application, where (a) is the experimental absorption spectrum. Simulated absorption spectrum (b). (c) Kohn-Sham molecular orbital energy level diagram, and shows Cu 45 atomic orbital distributions of each molecular orbital. (d) Frontier orbitals, including HOMO-1, HOMO-2, HOMO, and LUMO.;

[0037] Figure 5 is a diagram of the stability test results of the copper nanoclusters in Example 3 of the present application, where (a) is the long-term stability test result under environmental conditions; (b) is the solid stability test result under acid, base, and heat conditions; (c) is the solution stability test result under acid, base, and heat conditions.

[0038] Figure 6 This is the test result graph of the electrocatalytic CO 2 reduction of copper nanoclusters in Example 4 of this application, where (a) is the test result of the linear voltammetry curve; (b) is the test result of the partial current density and Faraday efficiency of the gas-phase products at different voltages. Detailed implementation manners

[0039] The embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application.

[0040] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0041] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0042] In this document, the term "comprising" or "including" is an open expression, that is, it includes the content specified in the present application, but does not exclude other aspects.

[0043] In this document, the terms "optionally", "optional" or "option" generally mean that the subsequent events or conditions may or may not occur, and this description includes the cases where the events or conditions occur and the cases where the events or conditions do not occur.

[0044] In this document, the term "TD-DFT calculation" is a time-dependent density functional calculation, which is a time-domain calculation method based on density functional theory. The main purpose of TD-DFT is to solve the problem of the energy level of the excited state of a physical system. It can quickly and accurately solve the energy level of the excited state in a physical system at a relatively low computational cost.

[0045] In the first aspect of the present application, the present application provides a copper nanocluster, and the molecular formula of the copper nanocluster is Cu 45 H 6 X 18 Y 15, where X is a dehydrogenated alkyne ligand and Y represents a dehydrogenated acid ligand. Thus, this copper nanocluster is a 6-electron superatom copper nanocluster Cu 45 , introducing Cu + / Cu 0 interface, which has acid, base, heat, and long-term stability, enabling it to be applied to electrocatalytic CO 2 reduction reaction.

[0046] According to an embodiment of the present application, the acid ligand includes acetic acid. Thus, acetic acid, as a common organic acid ligand, has good chemical stability and tunability. Acetic acid binds to copper ions through its carboxyl group, thereby forming a stable ligand protection layer on the surface of the nanocluster.

[0047] According to an embodiment of the present application, the alkyne ligand includes at least one of alkynyl compounds with the general formula Z-C≡CH, where Z is a substituted or unsubstituted phenyl group, and the substituents of the phenyl group include at least one of trifluoromethyl, methyl, methoxy, fluorine, chlorine, bromine, and iodine. Thus, by selecting the alkyne ligand to regulate the electronic structure and surface properties of the copper nanocluster, its catalytic performance and stability can be optimized. It should be understood that when Z has substituents, the number of substituents can be one or more, and when the number of substituents is multiple, the substituents can be the same or different.

[0048] According to an embodiment of the present application, the molecular formula of the copper nanocluster is Cu 45 H 6 (C≡C-C 6 H 3 -3,5-(CF 3 ) 2 ) 18 (CH 3 COO) 15 . Thus, Cu 45 forms a metal core, H 6 binds to copper atoms to stabilize the cluster structure, 18 alkyne ligands bind to copper atoms, further stabilizing the cluster structure, and also affecting the electronic structure of the cluster through its electronic properties. 15 acetate ligands bind to copper atoms, further enhancing the stability of the cluster and regulating its electronic properties.

[0049] According to an embodiment of the present application, the core of the copper nanocluster is composed of 45 Cu, and the center is a double-capped icosahedron Cu 15 containing 15 Cu. The double-capped icosahedron is surrounded by a Cu 2 shell layer composed of Cu 30 units bridged by 15 acid ligands. 18 alkyne ligands are along the C 3The axis levels are arranged in 6 layers. Thus, this arrangement optimizes the structure of copper nanoclusters, promotes the strong interaction between the metal and the ligand, and thus significantly improves the acid, base, heat, and long-term stability of copper nanoclusters.

[0050] According to an embodiment of the present application, the alkyne ligand adopts μ 4 -η 1 ,η 1 ,η 1 , η 2 、μ 3 -η 1 ,η 2 ,η 2 、μ 5 -η 1 ,η 1 ,η 1 ,η 2 ,η 2 Three coordination modes. Thus, the strong interaction between the metal and the ligand is promoted, and the stability of copper nanoclusters is enhanced.

[0051] According to an embodiment of the present application, the acid ligand adopts μ 2 -η 1 ,η 1 Coordination mode. Thus, the strong interaction between the metal and the ligand is promoted, and the stability of copper nanoclusters is enhanced.

[0052] According to an embodiment of the present application, the copper nanoclusters have D 3 symmetry. Thus, the acid, base, heat, and long-term stability of copper nanoclusters are improved.

[0053] In a second aspect of the present application, the present application proposes a method for preparing the above-mentioned copper nanoclusters, including the following steps:

[0054] (1) Mix a copper precursor, an alkyne ligand, an acid ligand, and a first solvent to obtain a first solution;

[0055] (2) Mix the first solution with a base to obtain a second solution;

[0056] (3) Mix the second solution with a reducing agent to carry out a reduction reaction to obtain the copper nanoclusters.

[0057] The characteristics and effects described for the above copper nanoclusters also apply to this method and will not be elaborated here.

[0058] According to an embodiment of the present application, the copper precursor includes Cu(CH 3 CN) 4 A, where A represents an anion, and the anion is F -, Cl - , Br - , ClO 4 - , PF 6 - , OTf - , BF 4 , SbF 6 , NO 3 , CH 3 COO, CF 3 , SO 3 at least one of the following. As an example, the copper precursor is Cu(CH 3 CN) 4 PF 6 .

[0059] According to an embodiment of the present application, the molar ratio of the amounts of the copper precursor, the alkyne ligand, and the acid ligand is 10:(3 - 7):(4 - 8). For example, it can be 10:3:8, 10:4:7, 10:5:6, 10:6:5, 10:7:4, etc. Thus, by controlling the molar ratio of the amounts of the copper precursor, the acid ligand, and the alkyne ligand within the above range, on the one hand, the stability of the copper nanoclusters can be improved, and on the other hand, the reaction can be promoted to proceed stably and efficiently.

[0060] According to an embodiment of the present application, in the first solution, the amount of the first solvent is such that the concentration of the copper precursor in the first solution is 0.01 - 0.3 mol / L. For example, it can be 0.01 mol / L, 0.02 mol / L, 0.03 mol / L. Thus, the concentration of the copper precursor in the first solution is controlled to enable the uniform nucleation and growth of the copper nanoclusters.

[0061] According to an embodiment of the present application, the first solvent includes dichloromethane and methanol. Thus, a mixed solvent system of dichloromethane and methanol is used to dissolve the copper precursor and the ligand, thereby preparing a uniform reaction solution.

[0062] According to an embodiment of the present application, the base includes triethylamine. Thus, triethylamine acts as a basic reagent to neutralize the acidic substances generated in the reaction system, prevent its interference with the reaction, and promote the formation of copper nanoclusters.

[0063] According to an embodiment of the present application, relative to the amount of 1 mol of the copper precursor, the amount of the base is 0.5 - 1 mol. For example, it can be 0.5 mol, 0.6 mol, 0.7 mol, 0.8 mol, 0.9 mol, 1.0 mol, etc.

[0064] According to an embodiment of the present application, the reducing agent includes diphenylsilane. Thus, the copper ions in the copper precursor are reduced to zero-valent copper.

[0065] According to an embodiment of the present application, step (3) includes: adding the reducing agent to the second solution in batches, and the addition amount each time accounts for 10% to 70% of the total amount of the reducing agent. For example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 30%, 40%, 50%, 60%, 70%, etc. Thereby, it is avoided that the reduction effect of the reducing agent is weakened due to the catalytic action of copper causing hydrogen to overflow.

[0066] According to an embodiment of the present application, relative to 1 mol of the copper precursor, the amount of the reducing agent used is 0.5 to 2 mol. For example, it can be 0.5 mol, 0.6 mol, 0.7 mol, 0.8 mol, 0.9 mol, 1 mol, 2 mol, etc. Thereby, the reaction system is further stabilized.

[0067] According to an embodiment of the present application, the temperature of the reduction reaction is 10 to 40 °C, for example, it can be 10 °C, 11 °C, 12 °C, 13 °C, 14 °C, 15 °C, 16 °C, 17 °C, 18 °C, 19 °C, 20 °C, 30 °C, 40 °C, etc.; the time is 6 to 72 h, for example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, 20 h, 40 h, 60 h, 70 h, 72 h, etc.

[0068] According to an embodiment of the present application, in step (1), the mixing is carried out under stirring conditions, and the stirring time is 5 to 10 min. Thereby, the reaction proceeds stably.

[0069] According to an embodiment of the present application, in step (2), the mixing is carried out under stirring conditions, and the stirring time is 10 to 20 min. Thereby, the reaction proceeds stably.

[0070] According to an embodiment of the present application, the method further includes:

[0071] (4) Post-treating the crude copper precursor product obtained in step (3). The post-treatment method can refer to the existing process. For example, it can be to remove the solvent by rotary evaporation of the solution, and the obtained product is washed with n-hexane and methanol to obtain a powder product.

[0072] Optionally, the method includes:

[0073] (5) Crystallizing the powder product obtained in step (4). The crystallization treatment includes: dissolving the powder product in dichloromethane, performing tube diffusion with n-hexane, and the crystallization time is 2 to 10 days to obtain copper nanocluster crystals.

[0074] In the third aspect of the present application, the present application proposes the above-mentioned copper nanoclusters in electrocatalytic CO 2Applications in reduction reactions.

[0075] The characteristics and effects described for the above copper nanoclusters are equally applicable to this application and will not be elaborated here.

[0076] The solutions of this application will be explained below in conjunction with examples. Those skilled in the art will understand that the following examples are only for illustrating this application and should not be regarded as limiting the scope of this application. For those without specific techniques or conditions noted in the examples, the techniques or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchases.

[0077] Example 1: Preparation of Copper Nanoclusters

[0078] Dissolve Cu(CH 3 CN) 4 PF 6 (746 mg, 2 mmol), Cu(CH 3 COO)(120 mg, 1 mmol), and 3,5-(CF 3 ) 2 -C 6 H 3 -C≡CH (3,5-bis(trifluoromethyl)phenylacetylene, 1.2 mmol, 204 μL) in a mixed solution of 100 mL of dichloromethane and 15 mL of methanol. After stirring for 10 min, add Et 3 N (200 μL, 1.44 mmol) and continue stirring for 15 min. Subsequently, add a solution of 5 mL of methanol and Ph 2 SiH 2 (240 μL, 1.30 mmol). After stirring for 4 hours, add Ph 2 SiH 2 (120 μL, 0.65 mmol), continue stirring for 5 h, spin dry, wash with n-hexane, and directly obtain a black powder product with a yield of 86% (based on Cu).

[0079] Take 5 mg of the powder product and dissolve it in dichloromethane. Perform tube diffusion with n-hexane. After seven days, obtain a black block single crystal.

[0080] Example 2: Characterization of Copper Nanoclusters

[0081] Characterize the single crystal product prepared in Example 1. The single crystal data of the single crystal product are collected by testing with a single crystal X-ray diffractometer, all collected on an Agilent SuperNova, using CuK α , and the results are as shown in Figure 1 and Figure 2 .

[0082] The time-resolved mass spectrometry (ESI-MS) test of the single-crystal product was collected using a Bruker impact II, and the results are as Figure 3 shown.

[0083] The ultraviolet-visible absorption spectrum of the single-crystal product was collected using a Cary 5000, with a 10 mm cuvette; the absorption spectrum of the single-crystal product and the TD-DFT calculation results are as Figure 4 shown.

[0084] Figure 1 is a schematic diagram of the single-crystal structure of copper nanoclusters. As shown in the figure, Cu 45 is a neutral cluster with an overall composition of [Cu 45 H 6 (C≡CR) 18 (OAc) 15 , consisting of eighteen alkynyl ligands and fifteen acetate ligands. The eighteen RC≡C - ligands are hierarchically arranged in six layers along the C 45 axis of the Cu 3 metal core. The overall cluster has D 3 symmetry, and these alkynyl ligands exhibit three different arrangements. Specifically, the two poles are each occupied by six μ 4 -η 1 ,η 1 ,η 1 , η 2 type RC≡C - ligands, while the equatorial region accommodates six μ 3 -η 1 ,η 2 ,η 2 ligands. The remaining six RC≡C - ligands adopt an unusual μ 5 -η 1 ,η 1 ,η 1 ,η 2 ,η 2 coordination mode, which promotes strong interactions between the metal and the ligands and enhances the stability of the cluster. The fifteen acetate ligands coordinate in a μ 2 -η 1 ,η 1 mode and are located at the edges of the bicapped icosahedron.

[0085] Figure 2 is a schematic diagram of the metal core structure of copper nanoclusters. As shown in the figure, the metal core of Cu 45 exhibits a core-shell structure, with a bicapped icosahedron Cu 15。The Cu bridged by acetic acid around it 2 units composed of Cu 30 is surrounded by a shell. Fifteen Cu 45 units of Cu 2 are symmetrically connected to the central Cu 15 core, presenting D 3 symmetry.

[0086] Figure 3 is the mass spectrometry data graph of copper nanoclusters. As shown in the figure, in the positive ion mode, the ESI-MS of the neutral sample of Cu 45 shows three significant peaks, corresponding to [Cu 42 H 6 (C≡CR) 18 (OAc) 12 H 2 2+ (m / z = 3824.7), [Cu 43 H 6 (C≡CR) 18 (OAc) 13 H 2 2+ (m / z = 3885.7) and [Cu 44 H 6 (C≡CR) 18 (OAc) 14 H 2 2+ (m / z = 3947.7) ions. The isotope pattern of the cluster perfectly matches the simulation results. Combining the detailed analysis of the single crystal structure, the ESI-MS data not only indicates that each Cu 45 cluster should contain 6 hydrides, but also confirms that the number of electrons in the Jellium model is 6 (n = 45 - 18 - 15 - 6), which makes the cluster behave as a six-electron superatom.

[0087] Figure 4 is the absorption spectrum of copper nanoclusters and the TD-DFT calculation results. As shown in Figure 4 a and 4b, the simulated absorption spectrum of Cu 45 is in good agreement with the corresponding experimental spectrum in terms of peak pattern and position, except for a slight red shift. It is known that the GGA functional usually underestimates the excitation energy by about 0.3 - 0.5 eV. The relatively large energy gap ΔHL = 1.46 eV endows the cluster with stability and enhances its resistance to the chemical environment ( Figure 4 c). As shown in Figure 4 ​​​As shown in c, the first absorption band (α) of Cu45 appears at 830 nm, mainly attributed to the transition from HOMO-1 to LUMO+1 (90.2%), with an oscillator strength of 0.109, which is significantly larger. The Kohn-Sham molecular orbital energy level diagram shows that this transition (peak α) exhibits obvious metal-to-metal charge transfer characteristics. The higher energy absorption band (β) is mainly composed of the transitions from HOMO to LUMO+3 and from HOMO-12 / 15 to LUMO, followed by another incompletely resolved band (γ), mainly attributed to the transitions from deeper HOMO-30 / 36 to LUMO / LUMO+1 and from HOMO / HOMO-1 to higher LUMOs. It is worth noting that the HOMO-1 / HOMO-2 / LUMO orbitals of Cu 45 significantly exhibit superatomic P-orbital characteristics ( Figure 4 d), while the LUMO-2 state exhibits superatomic S-orbital characteristics. Therefore, the valence electron structure of Cu 45 is consistent with the electron configuration of 1S21P, conforming to the electron arrangement of superatoms. The superatomic characteristics of Cu45 indicate that it has the most stable energy structure, which is consistent with our experimental observations.

[0088] Example 3: Stability test of copper nanoclusters

[0089] The product prepared in Example 1 was subjected to a stability test. Figure 5 is the stability test result diagram of copper nanoclusters. As shown in the figure, (a) indicates that under ambient conditions of normal temperature and pressure, the copper nanoclusters have long-term stability and can be stable for at least 28 days; (b) indicates that the copper nanoclusters can maintain solid stability under the conditions of 100 °C, 30% H 2 O 2 , 1M HCl, and 20M KOH; (c) indicates that the copper nanoclusters can maintain solution stability under the conditions of 95 °C, 10000eq.TEA, 100eq.HOAc, and 100eq.H 2 O 2 .

[0090] Example 4: Application of copper nanoclusters in electrocatalytic CO2 reduction reaction

[0091] The product prepared in Example 1 was subjected to an electrocatalytic CO 2 reduction test. Figure 6 is the electrocatalytic CO 2 reduction test result diagram of copper nanoclusters. As shown in the figure, the CO 2 reduction reaction experiment was carried out in a flow cell, using a carbon paper electrode coated with the catalyst and 1M KOH electrolyte. Among them, (a) the linear sweep voltammetry (LSV) results show that in the CO2 Under saturated conditions, Cu 45 Compared with N 2 Under purging conditions, it exhibits a higher current density and a more positive onset potential, indicating its electrocatalytic activity in CO reduction. (b) indicates that Cu 45 For C 2 H 4 Significant selectivity for the product. At -1.6 V, C 2 H 4 The maximum Faradaic efficiency of the product reaches 58.4%. These results demonstrate the potential of Cu 45 in optimizing the conversion of CO 2 into high-value products.

[0092] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0093] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A copper nanocluster, characterized in that: The molecular formula of the copper nanocluster is Cu 45 H6X 18 Y 15 , wherein X is a dehydrogenated alkyne ligand and Y represents a dehydrogenated acid ligand.

2. The copper nanoclusters according to claim 1, characterized in that The acid ligand includes acetic acid.

3. The copper nanoclusters according to claim 1, characterized in that: The alkyne ligand includes at least one of alkyne compounds of the general formula ZC≡CH, wherein Z is a substituted or unsubstituted phenyl group, and the substituent of the phenyl group includes at least one of trifluoromethyl, methyl, methoxy, fluorine, chlorine, bromine, and iodine.

4. The copper nanoclusters according to claim 1, characterized in that: The molecular formula of the copper nanocluster is Cu 45 H6(C≡C-C6H3-3,5-(CF3)2) 18 (CH3COO) 15 .

5. The copper nanocluster according to any one of claims 1 to 4, characterized in that The core of the copper nanocluster is composed of 45 Cu atoms, and the center is a double-capped icosahedral Cu containing 15 Cu atoms. 15 , a Cu2-dioctahedron consisting of 15 Cu2 units bridged by acid ligands 30 The shell surrounds the 18 alkyne ligands, which are arranged hierarchically in 6 layers along the C3 axis of the core; Optionally, the alkyne ligand adopts μ4-η 1 ,η 1 ,η 1 , η 2 、μ3-η 1 ,η 2 ,η 2 、μ5-η 1 ,η 1 ,η 1 ,η 2 ,η 2 three coordination modes; Optionally, the acid ligand is μ2-η 1 ,η 1 Coordination mode; Optionally, the copper nanoclusters have D3 symmetry.

6. A method for preparing the copper nanoclusters according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing a copper precursor, an alkyne ligand, an acid ligand and a first solvent to obtain a first solution; (2) mixing the first solution with a base to obtain a second solution; (3) Mixing the second solution with a reducing agent to perform a reduction reaction to obtain the copper nanoclusters.

7. The method according to claim 6, characterized in that The copper precursor includes Cu(CH3CN)4A, wherein A represents an anion, and the anion is F - , Cl - Br - 、ClO4 - PF6 - ,OTf - , BF4, SbF6, NO3, CH3COO, CF3SO3.

8. The method according to claim 6, characterized in that The molar ratio of the copper precursor, the alkyne ligand and the acid ligand is 10:(3-7):(4-8); Optionally, in the first solution, the first solvent is used in an amount such that the concentration of the copper precursor in the first solution is 0.01 to 0.3 mol / L; Optionally, the first solvent comprises dichloromethane and methanol; Optionally, the base comprises triethylamine; Optionally, the amount of the base is 0.5 to 1 mol relative to 1 mol of the copper precursor.

9. The method according to claim 6, characterized in that The reducing agent includes at least one of diphenylsilane; Optionally, step (3) comprises: adding the reducing agent to the second solution in batches, with the amount added each time accounting for 10% to 70% of the total amount of the reducing agent; Optionally, the amount of the reducing agent is 0.5 to 2 mol relative to 1 mol of the copper precursor; Optionally, the reduction reaction temperature is 10 to 40° C. and the time is 6 to 72 hours; Optionally, in step (1), the mixing is carried out under stirring conditions, and the stirring time is 5 to 10 minutes; Optionally, in step (2), the mixing is carried out under stirring conditions, and the stirring time is 10 to 20 minutes.

10. Use of the copper nanoclusters according to any one of claims 1 to 5 in electrocatalytic CO2 reduction reaction.

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