Rare earth-transition metal catalyst, preparation method and application thereof

Abstract

The application belongs to the technical field of rare earth-transition metal catalyst preparation, and discloses a rare earth-transition metal catalyst, a preparation method and application. The preparation method provided by the application is as follows: organic ligand Hmpa (3-methylpyridine-2-carboxylic acid), Dy(CF3SO3)3 and Cu(CF3SO3)2 are mixed and dissolved in a mixed solvent of CH3OH and CH3CN in a certain proportion, and are stirred, and blue strip-shaped crystals are obtained after the reaction is completed. The rare earth-transition metal catalyst is a three-prism-shaped metal skeleton structure, can be applied to the preparation of electrocatalytic materials, serves industrialized electrocatalytic technology, and helps energy transformation and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of rare earth-transition metal catalyst preparation technology, and relates to a rare earth-transition heterometallic catalyst, its preparation method and application. Background Technology

[0002] With the global energy crisis and environmental problems becoming increasingly prominent, clean and efficient energy conversion technologies have become a key research focus. Electrocatalysis, as a core support, is widely used in water splitting, fuel cells, and other fields, and its performance depends critically on the structure and activity of the electrocatalyst (Applied Surface Science, 2020, 514, 146073). High-nuclear heterometallic complexes (HNHCs), formed by ligand bridging of two or more metal ions, offer a new direction for the development of high-efficiency electrocatalysts due to their unique multinuclear structure, abundant active sites, and intermetallic synergistic effects. Research on HNHCs has gone through several stages. Early research focused on 3d-3d transition metal systems (such as Mn, Co, Ni, etc.), optimizing active sites by increasing the number of metal nuclei, and initially showing electrocatalytic potential. Subsequent development of noble metal-transition metal HNHCs improved activity, but the scarcity and high cost of noble metals limited large-scale applications. In recent years, 4f-3d rare earth-transition metal HNHCs have become a research hotspot. The unique 4f electron configuration of lanthanide ions (such as Dy³⁺ and Tb³⁺) can modulate the electronic state of the active center of transition metals, enhance catalytic kinetics, and improve charge transfer efficiency. At the same time, the synergistic effect between metals can reduce the activation energy of the reaction, optimize the adsorption and desorption of intermediates, and solve the problems of insufficient activity and stability of single metal catalysts (Advanced Functional Materials, 2025, 35, 2412345).

[0003] Water electrolysis is a crucial method for producing clean hydrogen energy, involving two half-reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Its efficiency under alkaline conditions determines the progress of industrialization. Existing alkaline water electrolysis catalysts suffer from drawbacks such as single active sites, difficulty in synergistically optimizing HER and OER performance, high energy consumption, and poor stability, hindering practical applications (ACS Catalysis, 2025, 15, 2104). Rare-earth-copper HNHCs combine the electronic regulation capabilities of rare-earth ions with the high catalytic activity of copper ions. Their application in alkaline water electrolysis can synergistically enhance both HER and OER performance, overcoming existing technological bottlenecks. These catalysts provide a new pathway for the design of highly efficient electrocatalysts, which is of great significance for promoting the industrialization of electrocatalysis, supporting energy transition, and achieving dual-carbon goals, making them a key research focus in this field. Summary of the Invention

[0004] The present invention aims to provide a rare earth-transition heterometallic catalyst, its preparation method and application. The rare earth-transition heterometallic catalyst contains one rare earth ion and six transition metal ions, has a triangular prism-shaped metal framework, and has excellent electrocatalytic performance.

[0005] The technical solution provided by this invention is as follows:

[0006] A rare earth-transition heterometallic catalyst, belonging to the monoclinic crystal system, has the molecular formula [DyCu6(mpa)6(OH)3(CH3CN)6](H2O)3(CF3SO3)6·H2O (complex 1, mpa = deprotonated 3-methylpyridine-2-carboxylic acid), space group Cc, and cell parameters: a = 23.167(2) Å, b = 39.874(4) Å, c = 13.086(4) Å, α = 90°, β = 91.0910(10)°, γ = 90°, V = 12086(4) Å. 3 .

[0007] A method for preparing the above-mentioned rare earth-transition heterometallic catalyst includes:

[0008] S1. Organic ligands Hmpa (3-methylpyridine-2-carboxylic acid), Dy(CF3SO3)3, and Cu(CF3SO3)2 are mixed and dissolved in a mixed solvent of CH3OH and CH3CN in a certain proportion to obtain a mixed solution;

[0009] S2. The mixed solution is stirred on a magnetic stirrer to react, and the rare earth-transition heterometallic catalyst is obtained after the reaction is completed.

[0010] The synthetic route for rare earth-transition heterometallic catalysts is shown in the following equation:

[0011]

[0012] In the above formula, complex 1 is [DyCu6(mpa)6(OH)3(CH3CN)6](H2O)3(CF3SO3)6·H2O.

[0013] Furthermore, in the above preparation method, the molar ratio of organic ligands Hmpa, Dy(CF3SO3)3, and Cu(CF3SO3)2 is 6:1:6.

[0014] Furthermore, the volume ratio of CH3OH to CH3CN in the mixed solvent is 1:1.

[0015] Furthermore, the amount of mixed solvent used is 4-8 mL for every 0.1 mmol of organic ligand Hmpa.

[0016] Furthermore, the amount of mixed solvent used is 6 mL for every 0.1 mmol of organic ligand Hmpa.

[0017] The present invention also provides an application of the above-mentioned rare earth-transition heterometallic catalyst or the rare earth-transition heterometallic catalyst prepared by the above preparation method in electrocatalysis technology.

[0018] This invention employs a room-temperature volatilization synthesis strategy to obtain a rare-earth-transition heterometallic catalyst with a triangular prism metal framework. The preparation method is simple and the raw materials are readily available. By designing organic ligand structures to react with different rare-earth metals and transition metals to form rare-earth-transition heterometallic catalysts, the structural types of rare-earth-transition complexes are enriched, providing a new direction for the exploration of their structural fields. The synthesized compound can be applied to the electrocatalytic reaction of water splitting under alkaline conditions, which is of great significance for promoting the industrial application of electrocatalysis technology and assisting in energy transition and environmental protection. Attached Figure Description

[0019] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 The images show crystal photographs of complex 1 prepared in Example 1 and product photographs from Examples 2-4.

[0021] Figure 2 The molecular structure diagram of coordination compound 1;

[0022] Figure 3 Coordination environment diagram of different metal ions at the center of coordination compound 1;

[0023] Figure 4 The infrared spectrum of complex 1;

[0024] Figure 5 Powder X-ray diffraction pattern of complex 1;

[0025] Figure 6 The electrocatalytic HER performance of complex 1 is shown in the figure.

[0026] Figure 7 The graph shows the electrocatalytic OER performance of complex 1. Detailed Implementation

[0027] Detailed Description of Embodiments The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and equivalent alterations or modifications also fall within the scope defined by the claims of this application.

[0028] It should be noted that the terms used in this application are generally those commonly used by those skilled in the art. If there is any inconsistency with commonly used terms, the terms used in this application shall prevail.

[0029] It should be noted that all reagents in the following examples were purchased directly from the market and were of analytical grade, without further purification before use.

[0030] Example 1: Preparation of [DyCu6(mpa)6(OH)3(CH3CN)6](H2O)3(CF3SO3)6·H2O (Complex 1)

[0031] Dy(CF3SO3)3 (0.02 mmol), Cu(CF3SO3)2 (0.12 mmol), and the organic ligand Hmpa (0.12 mmol) were dissolved in 2 mL of CH3OH and 8 mL of acetonitrile solution. The mixture was placed on a magnetic stirrer and stirred at room temperature for 2 h. After filtration, the mixture was allowed to stand to evaporate. After about three days, blue strip-shaped crystals were obtained, which is the target complex 1.

[0032] Example 2: Dy(CF3SO3)3 (0.02 mmol), Cu(CF3SO3)2 (0.12 mmol), and the organic ligand Hmpa (0.12 mmol) were dissolved in 2 mL CH3OH and 8 mL H2O. The mixture was placed on a magnetic stirrer and stirred at room temperature for 2 h. After filtration, the mixture was allowed to stand to evaporate. After about three days, light blue blocky crystals were obtained.

[0033] Example 3: Cu(CF3SO3)2 (0.12 mmol) and the organic ligand Hmpa (0.12 mmol) were dissolved in 2 mL CH3OH and 8 mL H2O. The mixture was placed on a magnetic stirrer and stirred at room temperature for 2 h. After filtration, the mixture was allowed to stand to evaporate. After about three days, a dark blue solution was obtained.

[0034] Example 4: DyCl3 (0.02 mmol), CuCl2 (0.12 mmol), and the organic ligand Hmpa (0.12 mmol) were dissolved in 2 mL of CH3OH and 8 mL of H2O. The mixture was placed on a magnetic stirrer and stirred at room temperature for 2 h. After filtration, the mixture was allowed to stand to evaporate. After about three days, a dark blue solution was obtained.

[0035] Figure 1 The images show crystal photographs of complex 1 prepared in Example 1 and product photographs of Examples 2-4. Specifically, image a shows a crystal photograph of complex 1, image b shows light blue crystals of the product from Example 2, image c shows a dark blue solution from Example 3, and image d shows a dark blue solution from Example 4.

[0036] Example 5: Crystal Structure Determination

[0037] High-quality single crystals were selected from the blue strip-shaped crystals obtained in Example 1 for structural determination. X-ray single-crystal diffraction data were collected using a Bruker APEX II diffractometer. The radiation source was Mo Kα radiation purified by a graphite monochromator (λ = 0.71073 Å). The crystal structure was analyzed using the SHELXS-2014 program, and subsequent structural refinement was performed using the SHELXL-2014 software package. During the structural analysis, the positions of non-hydrogen atoms were first determined using the difference Fourier synthesis method, and then the structural parameters were optimized using the full matrix least squares method. All non-hydrogen atoms were refined using an anisotropic displacement parameter model, and disordered solvent molecules were removed using the SQUEEZE function of PLATON software.

[0038] Figure 2 The molecular structure diagram of coordination compound 1 is shown. According to... Figure 2 It can be seen that the asymmetric unit of complex 1 includes one Dy III Ions, 6 Cu II Ions and 5 deprotonated quinha 2- Ligands. In terms of spatial arrangement, the metal ions form two coplanar triangular structural units, and these two triangles share the central Dy1 ion, which together with the surrounding Cu2, Cu5, Cu6, Cu3, Cu4 and Cu7 form a triangular prism metal framework.

[0039] Dy1 is a nine-coordinated structure. Some of the calculated data for its coordination configuration are shown in Table 1, which presents a three-cap triangular prism coordination configuration.

[0040] Table 1. Partial calculation data of the coordination configuration of Dy1 in coordination compound 1.

[0041]

[0042] Note: CCU-9 = single-cap cube; JCSAPR-9 = Johnson-type single-cap square inverse prism (J10); CSAPR-9 = single-cap square inverse prism; JTCTPR-9 = Johnson-type triple-cap triangular prism (J51); TCTPR-9 = triple-cap triangular prism; JTDIC-9 = triangular icosahedron (J63).

[0043] The calculated coordination configurations of Cu1, Cu4, and Cu5 are shown in Table 2. According to Table 2, Cu1, Cu4, and Cu5 exhibit a tetragonal pyramidal coordination configuration with their respective five surrounding coordinating atoms.

[0044] Table 2 Calculated data of coordination configurations of Cu1, Cu4 and Cu5 in coordination compound 1

[0045]

[0046] Note: PP-5 = pentagon; vOC-5 = Johnson's square pyramid; TBPY-5 = triangular bipyramid; SPY-5 = square pyramid; JTBPY-5 = Johnson's triangular bipyramid (J12).

[0047] The calculated coordination configurations of Cu2, Cu3, and Cu6 are shown in Table 3. According to Table 3, Cu2, Cu3, and Cu6 exhibit an octahedral coordination configuration with their respective six surrounding coordinating atoms.

[0048] Table 3 Calculated data on the coordination configurations of Cu2, Cu3 and Cu6 in coordination compound 1

[0049]

[0050] Note: HP-6 = hexagon; PPY-6 = pentagonal pyramid; OC-6 = octahedron; TPR-6 = triangular prism; JPPY-6 = Johnson's pentagonal pyramid J2.

[0051] Figure 3 This is a diagram showing the coordination environment of different metal ions at the center of complex 1.

[0052] Figure 3 Figure a shows the coordination environment of Dy1. It can be seen that among the nine coordinating atoms of Dy1, six ligand ions are mpa. - Each of the following pairs provides one oxygen atom: O1, O3, O5, O7, O9, O11. The other three oxygen atoms (O13, O14, O15) are formed by OH groups. - supply.

[0053] Figure 3 Figure b shows the coordination environment of Cu1. It can be seen that among the six coordinating atoms of Cu1, the O1 and N1 atoms are connected by a single ligand ion, MPa. - Provided, an O6 atom is supplied by another ligand ion mpa - Provided, an O13 atom is composed of OH - The ions provide, and there is also an N7 atom from the CH3CN solvent.

[0054] Figure 3Figure c shows the coordination environment of Cu2. It can be seen that among the six coordinating atoms of Cu2, the O3 and N2 atoms are connected by a single ligand ion, MPa. - Provided, an O2 atom is supplied by another ligand ion mpa - Provided, an O14 atom is composed of OH - The ions provide one N8 atom from the CH3CN solvent and one O17 atom from the H2O molecule.

[0055] Figure 3 Figure d shows the coordination environment of Cu3. It can be seen that among the six coordinating atoms of Cu3, the O5 and N3 atoms are connected by a single ligand ion, MPa. - Provided, an O4 atom is supplied by another ligand ion mpa - Provided, an O15 atom is composed of OH - The ions provide one N9 atom from the CH3CN solvent and one O18 atom from the H2O molecule.

[0056] Figure 3 Figure e shows the coordination environment of Cu4. It can be seen that among the six coordinating atoms of Cu4, the O7 and N4 atoms are connected by a single ligand ion, MPa. - Provided, an O12 atom is supplied by another ligand ion mpa - Provided, an O13 atom is composed of OH - The ions provide one N10 atom from the CH3CN solvent and one O16 atom from the H2O molecule.

[0057] Figure 3 Figure f shows the coordination environment of Cu5. It can be seen that among the six coordinating atoms of Cu5, O9 and N5 atoms are connected by a single ligand ion mpa. - Provided, an O8 atom is supplied by another ligand ion mpa - Provided, an O14 atom is composed of OH - The ions provide, and there is also an N11 atom from the CH3CN solvent.

[0058] Figure 3 The middle g diagram shows the coordination environment of Cu6. It can be seen that among the six coordinating atoms of Cu6, the O11 and N6 atoms are connected by a single ligand ion mpa. - Provided, an O10 atom is supplied by another ligand ion mpa - Provided, an O15 atom is composed of OH - The ions provide, and there is also an N112 atom from the CH3CN solvent.

[0059] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

[0060] Example 6: Infrared Spectroscopic Characterization

[0061] At 4000-500 cm - The complex 1 was characterized by infrared (FT-IR) analysis in band ¹. The results of the infrared spectral analysis are as follows: Figure 4 As shown. Complex 1 at 3750 cm⁻¹ -1 There is a nearby associated hydroxyl peak, attributed to the stretching vibration of OH molecules on the organic ligand and coordinated water molecules. And at 1300 cm⁻¹... -1 The presence of CH stretching vibration absorption peaks indicates that the organic ligand Hmpa is involved in coordination.

[0062] Example 7: X-ray diffraction

[0063] To verify the phase purity of the complex, powder X-ray diffraction (PXRD) analysis was performed, and the results are as follows: Figure 5 As shown. By comparing the experimentally measured diffraction pattern with the theoretical diffraction pattern based on single-crystal structure simulation, it was found that the positions of the main diffraction peaks were highly consistent, confirming that the prepared complex has good phase purity. It should be noted that there is a certain difference in the diffraction peak intensity between the experimental and simulated spectra. This phenomenon is likely due to the preferred orientation effect of the crystals in the sample.

[0064] Example 8: Electrocatalytic HER Performance Test

[0065] At 1.0 mol·L -1 In a three-electrode system using KOH solution, an electrode coated with uncalcined complex 1 powder (denoted as electrode 1) was used as the working electrode for HER performance testing. The test results are as follows: Figure 6 As shown. Figure 6 a is the sweep speed of 5 mV·s -1 The LSV diagram was measured at the time. Comparison revealed that complex 1 exhibits certain electrocatalytic activity in HER. Figure 6 b is a comparison of the overpotential of the working electrode at partial current densities, with a current density of 1 mA·cm⁻¹. -2 At that time, the overpotential of electrode 1 was 420 mV; the current density was 5 mA·cm⁻¹. -2 At that time, the overpotential of electrode 2 was 525 mV. Figure 6 c is a comparison of the Tafel slopes of the working electrodes. The Tafel slope of electrode 1 is 297.8 mV·dec. -1 . Figure 6 d is the fitted EIS plot. EIS can analyze the charge transfer kinetics of the electrocatalyst HER process. Electrode 1 has a certain conductivity. Figure 6 e represents the CV curve of electrode 1 at different voltage frequencies. Plotting the current density and scan rate at a potential of 0.218 mV yields the linear change curve of the electrochemical double-layer capacitance (C0). dl ),like Figure 6 As shown in f, its slope value is usually used to reflect the size of the electrochemical active area of ​​a material. The C of electrode 1... dl The value is 0.017.

[0066] Example 9: Electrocatalytic OER Performance Test

[0067] At 1.0 mol·L -1 The OER performance of a working electrode composed of complex 1 powder was tested using a three-electrode system in KOH solution. The electrode coated with uncalcined complex 1 powder was designated as electrode 2. The test results are as follows: Figure 7 As shown. Figure 7 a is the sweep speed of 5 mV·s -1 The working electrode LSV was measured at the time. The image shows that electrode 2 has certain electrocatalytic performance in terms of OER. Figure 7 b is a comparison of the overpotential of the working electrode at certain current densities. From the figure, it can be seen that at a current density of 1 mA·cm⁻¹... -2 At that time, the overpotential of electrode 2 was 1726 mV; the current density was 5 mA·cm⁻¹. -2 At that time, the overpotential of electrode 2 was 1991mV. Figure 7 c is a comparison of the Tafel slopes of the working electrodes; the Tafel slope of electrode 2 is 357.8 mV·dec. -1 . Figure 7 d is the EIS diagram of the working electrode. It can be seen from the diagram that electrode 2 has a certain conductivity. Figure 7 e is the CV plot of electrode 3. Plotting the current density and scan rate at a potential of 1.118 mV yields C. dl Image, as Figure 7 As shown in f, the C of electrode 2 dl The value is 0.035 mF·cm -2 .

Claims

1. A rare earth-transition heterometallic catalyst, characterized in that, The rare-earth-transition heterometallic molecular-based magnet has a triangular prism-shaped metallic framework structure, belonging to the monoclinic crystal system, with the molecular formula [DyCu6(mpa)6(OH)3(CH3CN)6](H2O)3(CF3SO3)6·H2O, where mpa = deprotonated 3-methylpyridine-2-carboxylic acid, space group P21, and cell parameters: a = 23.167(2) Å, b = 39.874(4) Å, c = 13.086(4) Å, α = 90°, β = 91.0910(10)°, γ = 90°, V = 12086(4) Å. 3 .

2. A method for preparing a rare earth-transition heterometallic catalyst as described in claim 1, characterized in that, The preparation method includes the following steps: S1. The organic ligand Hmpa (3-methylpyridine-2-carboxylic acid), Dy(CF3SO3)3, and Cu(CF3SO3)2 are mixed and dissolved in a mixed solvent of CH3OH and CH3CN in a certain proportion to obtain a mixed solution. The organic ligand Hmpa is 3-methylpyridine-2-carboxylic acid. S2. The mixed solution is stirred on a magnetic stirrer to react. After the reaction is complete, blue strip-shaped crystals are obtained, which are the rare earth-transition heterometallic catalyst.

3. The preparation method according to claim 2, characterized in that, The molar ratio of the organic ligands Hmpa, Dy(CF3SO3)3, and Cu(CF3SO3)2 is 6:1:

6.

4. The preparation method according to claim 2, characterized in that, In the mixed solvent, the volume ratio of CH3OH to CH3CN is 1:

1.

5. The preparation method according to claim 4, characterized in that, The volume of mixed solvent used is 4-8 mL for every 0.1 mmol of organic ligand Hmpa.

6. The application of the rare earth-transition heterometallic catalyst as described in claim 1 in the preparation of electrocatalytic materials.

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