Heteroatom-modulated diatomic catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalytic materials, in particular to a heteroatom-modulated diatomic catalyst and a preparation method and application thereof.The preparation method comprises the steps that binuclear metal complex molecules, zinc salt and an organic solvent are mixed, an obtained mixed solution and a 2-methylimidazole solution are stirred and mixed under the dark condition, and a mixture is obtained; and carrying out heat treatment on the obtained composite material to obtain the heteroatom-modulated diatomic catalyst. The method comprises the following steps: introducing a binuclear metal complex molecule containing heteroatoms into MOF in advance, and carrying out further heat treatment to construct a stable diatomic active center in which the heteroatoms participate in regulation on a nitrogen-doped carbon substrate; the introduction of heteroatoms not only can enhance the stability of diatomic sites and prevent agglomeration of the diatomic sites in heat treatment and electrochemical processes, but also can generate a strong catalytic effect through the unique geometric and electronic effects and fine regulation and control of the electronic structure of the binuclear center of the diatoms, thereby significantly improving the intrinsic activity and stability of the diatomic sites to ORR.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, and in particular to a heteroatom-modulated diatomic catalyst, its preparation method, and its application. Background Technology

[0002] The commercial application of zinc-air batteries is largely limited by the slow kinetics of the oxygen reduction reaction (ORR) that occurs on the air cathode. The ORR process involves multiple complex electron transfer steps, and its slow reaction rate leads to key bottlenecks in the battery, such as high charge / discharge overpotential, low energy efficiency, insufficient power density, and short cycle life.

[0003] Dual-atom catalysts (DACs), as an emerging and cutting-edge catalytic system, are attracting increasing attention. DACs, especially homonuclear diatomic catalysts (such as Fe2), not only inherit the high atom utilization advantage of single-atom catalysts (SACs), but also exhibit synergistic catalytic effects not found at single-atom sites because their two adjacent metal atoms can form unique binuclear active centers. This synergistic effect can effectively alter reaction pathways, optimize the adsorption / desorption behavior of key reaction intermediates, and even directly cleave OO bonds, thereby potentially significantly reducing the reaction energy barrier of ORR and improving catalytic activity and selectivity.

[0004] Despite the promising prospects of diatomic catalysts, their precise synthesis and electronic structure control still face significant challenges, including how to prevent the migration and aggregation of metal atoms, and how to finely control the local coordination environment of the constructed diatomic sites.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a heteroatom-modulated diatomic catalyst, its preparation method and application, in order to solve the problem that the existing processes for preparing diatomic catalysts cannot effectively prevent metal migration and aggregation.

[0007] The technical solution of the present invention is as follows: A method for preparing a heteroatom-modulated diatomic catalyst includes the following steps: A mixed solution is obtained by mixing a binuclear metal complex molecule, a zinc salt, and an organic solvent. 2-Methylimidazole was mixed with an organic solvent to obtain a 2-methylimidazole solution; The mixed solution and the 2-methylimidazole solution were stirred and mixed under light-protected conditions to obtain the composite material; The composite material was subjected to heat treatment to obtain a heteroatom-modulated diatomic catalyst.

[0008] The method for preparing the heteroatom-modulated diatomic catalyst, wherein the binuclear metal complex molecule is selected from bis(tetrachlorophenylferroporphyrin), bis(tetrachlorophenylmanganeseporphyrin), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride, [1,1'-bis(diphenylphosphino)ferrocene]nickel dichloride, (1,1'-bis(diphenylphosphino)ferrocene)cobalt dichloride, M-oxo-bis(tetrachlorophenylporphyrin)manganese, [μ-C6H4-1,2-(κ-)-cobalt(x ... 2 One or more of [-S)2][Fe2(CO)6].

[0009] The method for preparing the heteroatom-modulated diatomic catalyst, wherein the zinc salt is selected from one or more of zinc nitrate, zinc acetate, and zinc chloride; and the organic solvent is selected from one or more of methanol, ethanol, isopropanol, N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0010] The method for preparing the heteroatom-modulated diatomic catalyst, wherein the molar ratio of the binuclear metal complex molecule to the zinc salt is (0.01-0.05):(4-12).

[0011] In the method for preparing the heteroatom-modulated diatomic catalyst, the concentration of the 2-methylimidazole solution is 0.3 mmol / mL to 1 mmol / mL.

[0012] The method for preparing the heteroatom-modified diatomic catalyst further includes, after mixing the mixed solution with the 2-methylimidazole solution under light-protected conditions: The precipitate was obtained by centrifugation or vacuum filtration. The precipitate was dried at 40℃-80℃ to obtain the composite material.

[0013] The method for preparing the heteroatom-modulated diatomic catalyst includes a heating rate of 2℃ / min-8℃ / min, a heat treatment temperature of 900℃-1100℃, and a heat treatment time of 1h-3h.

[0014] The method for preparing the heteroatom-modulated diatomic catalyst, wherein the heat treatment is carried out under an inert atmosphere; Preferably, the heat treatment is performed by introducing argon gas to provide an inert atmosphere; the flow rate of the argon gas is 50 SCCM-120 SCCM.

[0015] A heteroatom-modulated diatomic catalyst is prepared using a method for preparing heteroatom-modulated diatomic catalysts.

[0016] Application of a heteroatom-modulated diatomic catalyst in a metal-air battery.

[0017] Beneficial Effects: This invention provides a heteroatom-modified diatomic catalyst, its preparation method, and its application. The preparation method includes the following steps: mixing a binuclear metal complex molecule, a zinc salt, and an organic solvent to obtain a mixed solution; mixing 2-methylimidazole with an organic solvent to obtain a 2-methylimidazole solution; stirring and mixing the mixed solution and the 2-methylimidazole solution under light-protected conditions to obtain a composite material; and heat-treating the composite material to obtain the heteroatom-modified diatomic catalyst. This invention uses a zeolite imidazole framework-8 (ZIF-8) MOF as a support. By pre-introducing a heteroatom-containing binuclear metal complex molecule into the MOF, and further heat-treating it, a stable, heteroatom-modulated diatomic active center is constructed on a nitrogen-doped carbon substrate. The introduction of heteroatoms not only enhances the stability of the diatomic sites and prevents their aggregation during heat treatment and electrochemical processes, but also, through their unique geometric and electronic effects, finely modulates the electronic structure of the dinuclear center, generating a powerful catalytic effect, thereby significantly improving its intrinsic activity and stability for ORR. Furthermore, applying the heteroatom-modulated diatomic catalyst to the air cathode of a zinc-air battery can significantly reduce the overpotential of the battery during charging and discharging, improve its power density and cycle life, and provide a novel catalyst for the development of next-generation high-performance, low-cost metal-air batteries. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of a method for preparing a heteroatom-modulated diatomic catalyst according to the present invention. Figure 2 XRD characterization diagrams of ZIF-8, ZIF-8 / Fe2TPP and ZIF-8 / Fe2TPPCl prepared in Example 1; Figure 3 An optical image of ZIF-8 / Fe2TPPCl prepared in Example 1 placed in a sintering boat; Figure 4 Transmission electron microscope and high-angle annular dark-field imaging-scanning transmission electron microscope images of Fe2NC-Cl prepared in Example 1; Figure 5 The images show the cyclic voltammetry curve and cyclic stability test results for Fe2NC-Cl prepared in Example 1. Detailed Implementation

[0019] This invention provides a heteroatom-modulated diatomic catalyst, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0021] Metal-air batteries, especially zinc-air batteries (ZABs), are highly regarded due to their high theoretical energy density (~1086 Wh / kg). -1 Zinc-air batteries are considered to be a highly promising next-generation electrochemical energy device due to their outstanding advantages such as abundant raw material reserves, low cost, environmental friendliness, and good safety. However, the commercial application of zinc-air batteries is largely limited by the slow kinetics of the oxygen reduction reaction (ORR) that occurs on their air cathode.

[0022] Currently, platinum (Pt) and its alloys are the most efficient ORR benchmark catalysts. However, the scarcity, high cost, and poor long-term stability of platinum (especially under reversible oxygen reduction / oxygen evolution reaction conditions) severely limit its application in large-scale energy devices. Therefore, developing high-performance, low-cost, and highly stable non-precious metal ORR catalysts is key to promoting the development of advanced energy technologies such as zinc-air batteries. Among many non-precious metal catalysts, atomically dispersed MNC (M represents transition metal, such as Fe, Co, etc.) single-atom catalysts (SACs) have made significant progress in the past decade due to their highest atom utilization, unique electronic structure, and excellent catalytic activity. In particular, Fe-NC catalysts have achieved ORR activity comparable to commercial Pt / C catalysts in alkaline media. However, the electronic structure of traditional single-atom Fe-N4 sites is relatively fixed, which is unsuitable for oxygen intermediates (such as... , , The adsorption energies of metal sites typically follow an inherent scaling relationship, which limits further optimization of the intrinsic activity of ORR. Furthermore, in complex electrocatalytic reaction environments, individual metal sites sometimes struggle to efficiently and synergistically activate reaction molecules, thus limiting the upper limit of their catalytic performance.

[0023] To overcome the limitations of single-atom catalysts, dual-atom catalysts (DACs) have been proposed. However, existing dual-atom catalysts still have the following problems: First, during the synthesis process, effectively preventing the migration and aggregation of metal atoms and achieving high-density, high-stability dual-atom site anchoring is a core challenge in material preparation. Second, and more importantly, how to finely control the local coordination environment of the constructed dual-atom sites to optimize their electronic structure and spin state, thereby maximizing their synergistic catalytic effect, is the decisive factor in improving their intrinsic activity. The traditional coordination environment is mainly composed of nitrogen (N) atoms, while introducing other heteroatoms (such as sulfur, phosphorus, halogens, etc.) for secondary coordination control is considered an effective strategy to break the electronic structure limitations of the traditional M-N4 site.

[0024] Based on this, such as Figure 1 As shown, this invention provides a method for preparing a heteroatom-modulated diatomic catalyst, comprising the following steps: Step S10: Mix the binuclear metal complex molecule, zinc salt and organic solvent to obtain a mixed solution; Step S20: Mix 2-methylimidazole with an organic solvent to obtain a 2-methylimidazole solution; Step S30: The mixed solution and the 2-methylimidazole solution are stirred and mixed under light-protected conditions to obtain the composite material; Step S40: The composite material is heat-treated to obtain a heteroatom-modulated diatomic catalyst.

[0025] In this embodiment, a zeolite imidazole framework-8 (ZIF-8) MOF is used as a support. By pre-introducing binuclear metal complex molecules containing heteroatoms into the MOF, and then further heat-treating, a stable, heteroatom-modulated diatomic active center is constructed on a nitrogen-doped carbon substrate. The introduction of heteroatoms not only enhances the stability of the diatomic sites and prevents their aggregation during heat treatment and electrochemical processes, but also, through their unique geometric and electronic effects, finely modulates the electronic structure of the diatomic binuclear center, generating a powerful catalytic effect, thereby significantly improving its intrinsic activity and stability for ORR. Furthermore, applying the heteroatom-modulated diatomic catalyst to the air cathode of a zinc-air battery can significantly reduce the battery's charge-discharge overpotential, improve its power density and cycle life, and provide a novel catalyst for developing next-generation high-performance, low-cost metal-air batteries.

[0026] Specifically, this preparation method is simple, low-cost, and environmentally friendly, enabling large-scale production. Furthermore, the constructed catalyst possesses a rich microporous carbon structure and a high active specific surface area, effectively improving the contact efficiency between the reaction substrate and the active sites. Simultaneously, coupled diatomic active centers are constructed within the catalyst, enabling synergistic catalytic effects. Heteroatom doping further allows for effective control of the geometry and electronic structure of the diatomic active centers, thereby optimizing their catalytic performance. In alkaline electrolytes, this diatomic catalyst exhibits superior electrocatalytic activity and long-term operational stability compared to commercial Pt / C catalysts for the oxygen reduction reaction.

[0027] In this embodiment, the preparation method has the following advantages: 1) Pre-encapsulation strategy of binuclear metal complexes in MOF: By pre-stabilizing and encapsulating binuclear metal complex molecules in MOF materials, the migration and aggregation of metal atoms during high-temperature pyrolysis are effectively suppressed, the formation of nanoparticles is avoided, and the precise construction of atomically dispersed catalysts is achieved. 2) In-situ doping and electronic structure regulation of heteroatom-containing ligands: This synthesis strategy does not require the introduction of additional heteroatom ligands. Instead, it utilizes the in-situ release of heteroatoms from binuclear metal complex molecules containing heteroatoms during pyrolysis, thereby achieving precise regulation of the geometric configuration and electronic structure of the diatomic iron active center, which significantly enhances the adsorption and activation ability of oxygen reduction reaction intermediates. 3) Excellent ORR electrocatalytic performance: The prepared catalyst exhibits ORR catalytic activity and long-term stability in alkaline electrolytes that surpass those of commercial Pt / C, and has good application prospects.

[0028] In some embodiments, the binuclear metal complex molecule is selected from bis(tetrachlorophenyl)ferroporphyrin, bis(tetrachlorophenyl)manganese porphyrin, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride, [1,1'-bis(diphenylphosphino)ferrocene]nickel dichloride, (1,1'-bis(diphenylphosphino)ferrocene)cobalt dichloride, M-oxo-bis(tetrachlorophenyl)porphyrin manganese, [μ-C6H4-1,2-(κ-)-cobalt(x ... 2 One or more of [-S)2][Fe2(CO)6]. Preferably, the binuclear metal complex molecule contains chlorine, and the chlorine atom can act as a ligand to directly coordinate with the metal center, or modify the position of the chlorine atom in the carbon support framework near the metal site; due to its strong electron-withdrawing properties, the introduction of chlorine can significantly change the electron cloud density of the central iron or manganese atom, adjust the d-band center position, and thus affect the adsorption strength of the catalyst for oxygen species; the present invention utilizes chlorine to adjust the diatomic metal site, which can achieve the adsorption of... and Simultaneous optimization of adsorption energy allows for breakthroughs in the theoretical limits of ORR activity.

[0029] Specifically, by pre-introducing binuclear metal complex molecules containing Cl atoms in the ligands into the MOF, and then further heat-treating them, stable diatomic metal active centers regulated by chlorine atoms can be constructed on a nitrogen-doped carbon substrate. The introduction of chlorine not only enhances the stability of the diatomic metal sites and prevents them from agglomerating during heat treatment and electrochemical processes, but also, through its unique geometric and electronic effects, finely regulates the electronic structure of the metal binuclear center, generating a powerful catalytic effect, thereby significantly improving its intrinsic activity and stability for ORR.

[0030] In some embodiments, the zinc salt is selected from one or more of zinc nitrate, zinc acetate, and zinc chloride; the organic solvent is selected from one or more of methanol, ethanol, isopropanol, N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide. Using the above-mentioned zinc salt as a raw material for preparing ZIF-8, a composite material of the binuclear metal complex molecule and ZIF-8 can be obtained by mixing it with a binuclear metal complex molecule and then reacting it with 2-methylimidazole in an organic solvent environment. The organic solvent provides a liquid reaction environment for the reaction, accelerating its complete progress.

[0031] In a preferred embodiment, the zinc salt is zinc nitrate; and the organic solvent is methanol.

[0032] In some embodiments, the molar ratio of the binuclear metal complex molecule to the zinc salt is (0.01-0.05):(4-12). By controlling the molar ratio of the binuclear metal complex molecule to the zinc salt within the above range, stable, heteroatom-regulated diatomic metal active centers (e.g., Fe2N6Cl) can be constructed on a nitrogen-doped carbon substrate after heat treatment.

[0033] Preferably, in step S10, the amount of the zinc salt is 4 mmol-12 mmol, the amount of the binuclear metal complex molecule is 0.01 mmol-0.05 mmol, and the volume of the organic solvent is 50 mL-100 mL.

[0034] In a preferred embodiment, the molar ratio of the binuclear metal complex molecule to the zinc salt is 0.02:8.

[0035] In some embodiments, the concentration of the 2-methylimidazole solution is 0.3 mmol / mL to 1 mmol / mL.

[0036] Preferably, in step S20, the amount of 2-methylimidazole is 30 mmol-50 mmol, and the volume of the organic solvent is 50 mL-100 mL.

[0037] In a preferred embodiment, the concentration of the 2-methylimidazole solution is 0.5 mmol / mL.

[0038] In some embodiments, in step S30, the stirring and mixing time under light-protected conditions is 5h-30h, and the stirring action can drive ZIF-8 nucleation and promote the formation of composite materials.

[0039] In some embodiments, after stirring and mixing the mixed solution with the 2-methylimidazole solution under light-protected conditions, the process further includes: centrifugation or vacuum filtration to obtain a precipitate; and drying the precipitate at 40°C-80°C to obtain the composite material. The composite material can be obtained by continuously stirring the reaction under light-protected conditions, collecting the precipitate, and then drying it.

[0040] In some embodiments, in addition to centrifugation or vacuum filtration combined with drying to obtain the composite material, the reacted mixture can also be dried directly in a vacuum oven or obtained by freeze drying.

[0041] In some embodiments, the heating rate of the heat treatment is 2℃ / min-8℃ / min, the temperature of the heat treatment is 900℃-1100℃, and the time of the heat treatment is 1h-3h.

[0042] In some embodiments, the heat treatment is performed under an inert atmosphere; preferably, the heat treatment is performed by introducing argon gas to provide an inert atmosphere; the flow rate of the argon gas is 50 SCCM-120 SCCM.

[0043] In this embodiment, metal atoms are captured and stabilized on the MOF-derived carbon support under high temperature conditions under inert gas protection to form metal active centers.

[0044] In a preferred embodiment, the heating rate of the heat treatment is 5°C / min, the temperature of the heat treatment is 950°C, the heat treatment time is 3 hours, and the flow rate of the argon gas is 90 SCCM.

[0045] In some embodiments, the heteroatom-modulated diatomic catalyst can also be prepared by simultaneously introducing two substances: a heteroatom-free bimetallic compound (such as nonacarbonyl diferric) and a heteroatom-containing compound (such as sodium sulfide).

[0046] In addition, the present invention also provides a heteroatom-modulated diatomic catalyst, which is prepared using the preparation method of the heteroatom-modulated diatomic catalyst.

[0047] In this embodiment, the diatomic catalyst prepared by the above method can not only enhance the stability of the diatomic sites and prevent them from agglomerating during thermal treatment and electrochemical processes by introducing heteroatoms, but also finely control the electronic structure of the diatomic binuclear center through its unique geometric and electronic effects, thereby generating a strong catalytic effect and significantly improving its intrinsic activity and stability for ORR.

[0048] Specifically, the chlorine-doped diatomic catalyst constructed using the MOF derivation strategy not only effectively utilizes the ordered porous structure of the MOF precursor to achieve uniform dispersion and stable anchoring of metal sites, but also significantly enhances the adsorption and activation capabilities of oxygen species by precisely controlling the geometric configuration and electronic structure of the diatomic iron active center through the introduction of chlorine atoms. This catalyst exhibits superior ORR activity and long-term stability compared to commercial Pt / C in alkaline media, successfully overcoming the structural and performance limitations of traditional single-atom materials and providing a new pathway for the design of highly efficient electrocatalysts.

[0049] In addition, the present invention also provides the application of a heteroatom-modulated diatomic catalyst in a metal-air battery.

[0050] In this embodiment, applying the heteroatom-modulated diatomic catalyst to the air cathode of a metal-air battery can significantly reduce the charge-discharge overpotential of the battery, improve its power density and cycle life, and provide a novel catalyst for the development of next-generation high-performance, low-cost metal-air batteries.

[0051] In some embodiments, the metal-air battery is a zinc-air battery.

[0052] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0053] Example 1 This embodiment provides a heteroatom-modulated diatomic catalyst, and the specific preparation process is as follows: 1) 0.02 mmol of bis(tetrachlorophenyl)ferroporphyrin (Fe2TPPCl) and 8 mmol of zinc nitrate hexahydrate were dispersed in 80 mL of methanol and stirred and sonicated to disperse the mixture, which was denoted as solution A. Then, 40 mmol of 2-methylimidazole was dissolved in 80 mL of methanol and stirred to dissolve the mixture, which was denoted as solution B. At room temperature, solution B was quickly poured into solution A and stirred continuously for 24 hours in the dark. Subsequently, the precipitate was collected by centrifugation and finally dried in a vacuum drying oven at 60 °C to obtain the composite material of bis(tetrachlorophenyl)ferroporphyrin / ZIF-8, denoted as ZIF-8 / Fe2TPPCl.

[0054] like Figure 2 As shown, the obtained ZIF-8 / Fe2TPPCl did not destroy the ZIF-8 crystal structure, and at the same time Figure 3 An optical image of ZIF-8 / Fe2TPPCl placed in a burning boat; ZIF-8 / Fe2TPPCl appears pale green.

[0055] 2) To further obtain a diatomic catalyst, ZIF-8 / Fe2TPPCl powder (approximately 120 mg) was evenly spread in a corundum sintering boat and then placed in a tube furnace for high-temperature heat treatment. Under an argon atmosphere, the gas flow rate was controlled at 90 SCCM and the heating rate was controlled at 5 °C / min. -1 The heat treatment temperature was controlled at 950℃ and the heat treatment time was controlled at 3 hours. After natural cooling, a catalyst with chlorine modulation diatomic iron was obtained, denoted as Fe2NC-Cl.

[0056] Transmission electron microscopy (TEM) and high-angle annular dark-field imaging-scanning transmission electron microscopy (HAADF-STEM) images of the obtained Fe2NC-Cl samples are attached. Figure 4 As shown, Figure 4 In the image, 'a' is a TEM image of Fe2NC-Cl, indicating that Fe2NC-Cl has a certain folded hollow structure. Figure 4 b in the image is the HAADF-TEM image of Fe2NC-Cl, showing that the metal in the surface carbon support exists in a typical atomic dispersion form; Figure 4 The ch in the image is a HAADF-TEM image, which further shows that the Fe atoms in the material exist in pairs (Fe-Fe) within the carbon support. Figure 4 In this context, 'i' represents energy-dispersive X-ray spectral mapping (EDS-mapping), indicating that chlorine was successfully doped into the carbon support to modulate the coordination environment of diatomic Fe.

[0057] 3) Electrochemical testing of the Fe2NC-Cl catalyst Electrochemical testing employed a three-electrode system. The Fe₂NC-Cl catalyst was supported on a glassy carbon electrode to obtain the working electrode, a graphite rod was used as the counter electrode, and Ag / AgCl (saturated KCl) was used as the reference electrode. ORR performance was measured using a Chenhua electrochemical workstation (CHI760E). Tests were conducted at a concentration of 0.1 mol·L⁻¹. -1 The experiment was conducted in KOH solution. Electrode activation scanning was first performed using cyclic voltammetry (CV), with linear sweep polarization (LSV) curves taken at 5 mV·s. -1 The sweep rate was measured, and the LSV curve test process used 95% resistance compensation. The test results are as follows: Figure 5 As shown in Figure a, Fe₂NC-Cl exhibits a half-wave potential of 0.924 V, which is higher than that of Fe₂NC (0.904 V), FeNC (0.880 V), NC (0.881 V), and commercially available Pt / C (0.876 V). Furthermore, Figure 5 In the figure, b represents the cyclic stability test of the catalyst. It can be seen that after 30,000 accelerated cycling tests (ADT), the half-wave potential of its LSV only decreased by 2 mV, showing excellent electrochemical stability.

[0058] In summary, this invention provides a heteroatom-modified diatomic catalyst, its preparation method, and its application. The preparation method includes the following steps: mixing a binuclear metal complex molecule, a zinc salt, and an organic solvent to obtain a mixed solution; mixing 2-methylimidazole with the organic solvent to obtain a 2-methylimidazole solution; stirring and mixing the mixed solution and the 2-methylimidazole solution under light-protected conditions to obtain a composite material; and heat-treating the composite material to obtain the heteroatom-modified diatomic catalyst. This invention uses a zeolite imidazole framework-8 (ZIF-8) MOF as a support. By pre-introducing a heteroatom-containing binuclear metal complex molecule into the MOF, and further heat-treating it, a stable, heteroatom-modulated diatomic active center is constructed on a nitrogen-doped carbon substrate. The introduction of heteroatoms not only enhances the stability of the diatomic sites and prevents their aggregation during heat treatment and electrochemical processes, but also, through their unique geometric and electronic effects, finely modulates the electronic structure of the dinuclear center, generating a powerful catalytic effect, thereby significantly improving its intrinsic activity and stability for ORR. Furthermore, applying the heteroatom-modulated diatomic catalyst to the air cathode of a zinc-air battery can significantly reduce the overpotential of the battery during charging and discharging, improve its power density and cycle life, and provide a novel catalyst for the development of next-generation high-performance, low-cost metal-air batteries.

[0059] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a heteroatom-modulated diatomic catalyst, characterized in that, Including the following steps: A mixed solution is obtained by mixing a binuclear metal complex molecule, a zinc salt, and an organic solvent. 2-Methylimidazole was mixed with an organic solvent to obtain a 2-methylimidazole solution; The mixed solution and the 2-methylimidazole solution were stirred and mixed under light-protected conditions to obtain the composite material; The composite material was subjected to heat treatment to obtain a heteroatom-modulated diatomic catalyst.

2. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, The binuclear metal complex molecule is selected from bis(tetrachlorophenyl)ferroporphyrin, bis(tetrachlorophenyl)manganese porphyrin, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride, [1,1'-bis(diphenylphosphino)ferrocene]nickel dichloride, (1,1'-bis(diphenylphosphino)ferrocene)cobalt dichloride, M-oxo-bis(tetrachlorophenyl)porphyrin manganese, [μ-C6H4-1,2-(κ) 2 One or more of [-S)2][Fe2(CO)6].

3. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, The zinc salt is selected from one or more of zinc nitrate, zinc acetate, and zinc chloride; the organic solvent is selected from one or more of methanol, ethanol, isopropanol, N,N-dimethylformamide, N,N-diethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, The molar ratio of the binuclear metal complex molecule to the zinc salt is (0.01-0.05):(4-12).

5. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, The concentration of the 2-methylimidazole solution is 0.3 mmol / mL to 1 mmol / mL.

6. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, After mixing the mixed solution with the 2-methylimidazole solution under light-protected conditions, the process further includes: The precipitate was obtained by centrifugation or vacuum filtration. The precipitate was dried at 40℃-80℃ to obtain the composite material.

7. The method for preparing the heteroatom-modulated diatomic catalyst according to claim 1, characterized in that, The heating rate of the heat treatment is 2℃ / min-8℃ / min, the temperature of the heat treatment is 900℃-1100℃, and the time of the heat treatment is 1h-3h.

8. The method for preparing the heteroatom-modulated diatom catalyst according to claim 1, characterized in that, The heat treatment is performed under an inert atmosphere; Preferably, the heat treatment is performed by introducing argon gas to provide an inert atmosphere; the flow rate of the argon gas is 50 SCCM-120 SCCM.

9. A heteroatom-modulated diatomic catalyst, characterized in that, It is prepared using the method for preparing heteroatom-modulated diatomic catalysts as described in any one of claims 1-8.

10. The application of a heteroatom-modulated diatomic catalyst as described in claim 9 in a metal-air battery.

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