Metal cluster catalyst as well as preparation method and application thereof

Abstract

The invention relates to a metal cluster catalyst and a preparation method and application thereof, and belongs to the technical field of catalyst material synthesis. The preparation method of the metal cluster catalyst comprises the following steps: dissolving two metal sources in a mixed solvent, performing uniform ultrasonic treatment, adding a chelating agent, and performing ultrasonic treatment to obtain a mixed solution; dispersing the mixed solution into a carrier material, fully stirring, and pyrolyzing to obtain the metal cluster catalyst. The preparation method is simple and convenient, short in working procedure time consumption, low in raw material price and easy to repeat, can be widely applied to various metal precursors and different carrier materials (including carbon-based and non-carbon-based materials), is simple in technological process, is suitable for large-scale production, and has important research significance and application potential.

Description

Technical Field

[0001] This application relates to the field of catalyst material synthesis technology, and in particular to a metal cluster catalyst, its preparation method, and its application. Background Technology

[0002] With the continuous iteration of new energy storage and energy conversion technologies, the demand for highly efficient electrocatalysts is becoming increasingly urgent. The electrocatalytic oxygen reduction reaction (ORR), as the core reaction in the cathode process of metal-air batteries and fuel cells, plays an indispensable role. However, the sluggish kinetics of the ORR process significantly restricts the improvement of energy conversion efficiency. Currently, platinum (Pt)-based catalysts remain the best-performing catalytic materials in the ORR field, but their high preparation costs and the scarcity of natural resources pose a severe bottleneck for large-scale practical applications. Therefore, developing non-precious metal electrocatalysts with both excellent catalytic activity and long-term stability to replace platinum group metals (PGMs) has become a research hotspot. This research direction not only helps reduce the preparation and application costs of catalysts but also has significant implications for promoting the industrialization and popularization of ORR electrocatalysis technology.

[0003] Among various non-noble metal catalyst candidate systems, atomically dispersed metal sites anchored on nitrogen-doped carbon substrates (typically represented by Fe-NC materials) have attracted widespread attention from academia and industry due to their advantages such as high atomic utilization and tunable electronic structure. However, traditional Fe-NC materials mostly exhibit a symmetrical Fe-N4 coordination configuration, which is not conducive to the key intermediate of the oxygen reduction reaction (… OOH, O and The adsorption energy of OH is generally too strong, which limits reaction kinetics, thus leaving room for further improvement in catalytic performance. Single-atom catalysts possess intrinsic advantages such as near 100% atom utilization, uniform active site structure, and unique electronic structure, exhibiting excellent activity and selectivity in various catalytic reactions, and have become a cutting-edge research hotspot in catalytic materials. However, recent studies have shown that single-metal-site catalysts still have several limitations: First, they possess only a single type of active site, making it difficult to overcome the energy barrier scaling relationship between different reaction intermediates; second, due to the low density of active sites, intermediates are prone to over-adsorption or occupation on the active sites, leading to catalyst deactivation; furthermore, in reactions involving multi-electron and multi-proton transfer, single-metal sites often struggle to efficiently drive complex reaction pathways, limiting their overall catalytic efficiency.

[0004] Atomic-scale dispersed metal nanoclusters, due to their unique geometric configurations and electronic structures, have proven to exhibit superior catalytic performance compared to single-atom, diatomic, and nanoparticle catalysts. Among them, bimetallic nanoclusters demonstrate even greater catalytic potential due to the synergistic effect of their binary metal components. Compared to single-metal nanoclusters, the charge transfer effect between different metal elements in bimetallic nanoclusters can modulate the local atomic charge states. The strength of this effect mainly depends on the differences in electronegativity, work function, Fermi level, and electron affinity between the two elements. Based on this characteristic, electron-rich reactants and reaction intermediates can achieve efficient adsorption and activation at the positively charged metal sites of bimetallic clusters, providing thermodynamic advantages for the smooth progress of the ORR reaction.

[0005] Chinese patent CN 118553933 A discloses a Fe2M bimetallic cluster catalyst, its preparation method, and its application. The synthesis method includes first preparing a C2N support by heating, annealing, and acid etching using urea, cyclohexanehexanone, and MgCl2 as raw materials; then preparing a Fe2M trinuclear molecular cluster by reacting a mixed solution of iron salt and metal M salt with sodium acetate; finally, mixing the C2N and Fe2M molecular clusters in ethanol, evaporating to dryness, and annealing under an inert atmosphere to obtain the Fe2M / C2N bimetallic cluster catalyst.

[0006] Chinese Patent CN 121192183 A discloses a locally tunable iron-nickel bimetallic fiber catalyst, its preparation method, and its applications. The method first involves dissolving ferric nitrate, nickel nitrate, and dicyandiamide in DMF to prepare solution A; then dispersing ZIF-8 nanoparticles and polyacrylonitrile in DMF to obtain solution B. After mixing A and B, a nanofiber membrane is prepared by electrospinning, and finally, after pre-oxidation and high-temperature carbonization, a carbon nanofiber catalyst with a heterostructure of iron-nickel bimetallic atoms / clusters is obtained.

[0007] Chinese Patent CN 120727855 B discloses a defect-supported porous carbon-based iron-based diatomic catalyst, its preparation method, and its application in air batteries. The method involves first heat-treating ZIF-8 under nitrogen protection at high temperature, followed by rapid cooling with liquid nitrogen to introduce defects. The catalyst is then mixed with an iron metal source in ethanol to backfill the defects. After stirring and drying, a second heating process is performed to finally obtain the defect-supported porous carbon-based iron-based diatomic catalyst. This method can precisely anchor and expose diatomic active sites, effectively preventing aggregation, and is suitable for air battery catalysis.

[0008] As can be seen from the existing technologies above, although the current mainstream technologies for preparing supported bimetallic catalysts each have their own focus, they generally suffer from problems such as complex processes, poor universality, or limited functionality, which restrict their large-scale application. Specifically, Reference 1 relies on a uniquely structured C2N support and a pre-synthesized molecular cluster precursor, resulting in a cumbersome synthesis route and limited support selection; Reference 2 employs a differential coordination strategy using electrospinning and organic ligands, which involves many process steps and high equipment requirements, making large-scale production difficult; Reference 3 stabilizes the metal sites through high-temperature defect construction and liquid nitrogen rapid cooling backfilling, but this process is energy-intensive and faces significant challenges in reproducibility, and none of the above methods address the corrosion resistance of the catalyst in chloride-containing environments (such as seawater electrolytes). Summary of the Invention

[0009] In view of this, this application provides a metal cluster catalyst, its preparation method and application. This application provides a universal, simple and functionally enhanced metal cluster catalyst preparation strategy. The entire preparation process uses readily available raw materials, has simple steps and good repeatability, and provides an innovative and efficient solution for the large-scale preparation and practical application of high-performance and corrosion-resistant metal cluster catalysts, which can effectively overcome the defects of the above-mentioned prior art.

[0010] The first aspect of this application provides a method for preparing a metal cluster catalyst, comprising the following steps:

[0011] At least one metal source is dissolved in a mixed solvent, sonicated to homogenize, and then a chelating agent is added. After sonication, a mixed solution is obtained. The mixed solution is dispersed in a support material, stirred thoroughly, and then pyrolyzed to obtain a metal cluster catalyst.

[0012] Preferably, the carrier material is selected from at least one of carbon nanotubes, graphene, Ketjen black, MOF materials, and COF materials, wherein the MOF material is ZIF-8 material.

[0013] Preferably, the preparation process of the ZIF-8 material is as follows: zinc nitrate hexahydrate is dissolved in anhydrous methanol and ultrasonicated to obtain solution A; dimethylimidazole is dissolved in anhydrous methanol to obtain solution B; solution A is rapidly added to solution B under stirring conditions, stirred and allowed to stand to precipitate, washed with anhydrous methanol and centrifuged three times, placed in an oven and dried to obtain ZIF-8 material.

[0014] Preferably, the specific process of stirring and allowing the sediment to settle is as follows: stirring for 90 minutes and then allowing the sediment to settle for 20-24 hours.

[0015] Preferably, the specific conditions for pyrolysis are as follows: pyrolysis is carried out under flowing argon gas, the pyrolysis temperature is 900℃, the heating rate is 5℃ / min, and the holding time is 2h.

[0016] Preferably, the metal source is selected from at least one of ferric chloride hexahydrate, anhydrous gallium trichloride, cobalt chloride, nickel chloride, palladium chloride, zinc chloride, tin chloride, manganese chloride, copper chloride, cobalt nitrate, ferric nitrate, nickel nitrate, manganese nitrate, and copper nitrate.

[0017] Preferably, the mixed solvent is composed of ethanol and water in a volume ratio of 1:1.

[0018] Preferably, the chelating agent is cyanamide.

[0019] Specifically, a method for preparing a metal cluster catalyst includes the following steps:

[0020] Zinc nitrate hexahydrate was dissolved in anhydrous methanol and sonicated to obtain solution A; dimethylimidazole was dissolved in anhydrous methanol to obtain solution B; solution A was rapidly added to solution B under stirring conditions, stirred and allowed to stand to precipitate, washed with anhydrous methanol and centrifuged three times, placed in an oven and dried to obtain ZIF-8 material.

[0021] 16 mg of ferric chloride hexahydrate and 9.6 mg of anhydrous gallium trichloride were dissolved in a mixed solvent (400 μL of ethanol and 400 μL of water in a 1:1 volume ratio). The solution was sonicated at 30-35°C until homogeneous. Then, 100 mg of chelating agent was added, and the solution was sonicated at 35°C for 30-50 min to obtain a mixed solution (the color of the mixed solution was light brownish-yellow after the addition of the chelating agent, and the color would be slightly darker after sonication at 35°C). The mixed solution was dispersed into 300 mg of ZIF-8 material (the mixed solution was added dropwise in 6 portions of 50 μL each time to ZIF-8 material. After each drop, the solution was ground evenly in a mortar (2-5 min) before the next drop was added. The color of ZIF-8 material changed from white to light brownish-yellow). After thorough stirring to promote uniform adsorption of ZIF-8 material, the solution was pyrolyzed to obtain the metal cluster catalyst.

[0022] Fe and Ga clusters do not function independently, but rather form a "superstructured composite active center." The Ga cluster surface has a high electron cloud density, which can induce a locally weakly negative surface charge environment, thereby preventing Cl from... - Direct contact with the catalytic active center. Fe clusters, as ORR active centers, provide the main d orbitals to bind to O2 molecules and reaction intermediates, thereby enhancing ORR activity.

[0023] The second aspect of this application also provides a metal cluster catalyst, which is prepared by the above method.

[0024] The third aspect of this application also provides the application of the aforementioned metal cluster catalyst in seawater zinc-air batteries.

[0025] Compared with the prior art, this application has the following advantages:

[0026] (1) The preparation process of this application is simple and convenient, and the reaction precursor is inexpensive and widely available, which can achieve high yield of the product. The catalyst prepared in this application has excellent dispersibility and structural stability, which can effectively inhibit particle agglomeration and activity decay during the catalytic process.

[0027] (2) The method of this application has strong universality and can be easily extended to various metal precursor systems, providing a general technical path for the controllable preparation of diversified non-precious metal catalysts.

[0028] (3) The catalyst prepared in this application can significantly accelerate the oxygen reduction reaction (ORR) kinetic process and effectively alleviate the electrode corrosion problem caused by chloride ions. When applied to seawater zinc-air batteries, it can significantly reduce voltage polarization. In addition, the process is adapted to large-scale production, which has both important academic research value and broad industrial application prospects. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 The XRD patterns of the catalysts FeGa / ZIF-8, Fe / ZIF-8 and Ga / ZIF-8 prepared in Examples 1-3 are shown below.

[0031] Figure 2 AC HAADF-STEM image of the FeGa / ZIF-8 catalyst prepared in Example 1;

[0032] Figure 3 Here is an AC HAADF-STEM image of the Fe / ZIF-8 catalyst prepared in Example 2;

[0033] Figure 4 Here is an AC HAADF-STEM image of the Ga / ZIF-8 catalyst prepared in Example 3;

[0034] Figure 5 Linear sweep voltammetry (LSV) curves of the catalysts FeGa / ZIF-8, Fe / ZIF-8, Ga / ZIF-8 and Pt / C prepared in Examples 1-3. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0037] In the following embodiments, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0038] Example 1: ZIF-8 supported FeGa metal cluster catalyst

[0039] (1) Preparation of ZIF-8 carrier: 4.464 g of zinc nitrate hydrate was dissolved in 120 ml of anhydrous methanol and sonicated for 20 min to obtain solution A; 4.928 g of dimethylimidazole was dissolved in 120 ml of anhydrous methanol to obtain solution B; solution A was quickly added to solution B under stirring conditions, stirred for 90 min and allowed to stand for 24 h to precipitate, washed with anhydrous methanol at 10500 rpm, centrifuged three times for 5 min, placed in an oven and dried to obtain a typical ZIF-8 carrier.

[0040] (2) Preparation of metal cluster catalyst: 16 mg of ferric chloride hexahydrate and 9.6 mg of anhydrous gallium trichloride were dissolved in a mixed solvent (a 1:1 mixture of ethanol (400 μL) and water (400 μL) by volume), and sonicated at 35°C until homogeneous. Then, 100 mg of cyanamide was added, and the mixture was sonicated at 35°C for 30 min to obtain a mixed solution (the mixed solution was light brownish-yellow after the addition of cyanamide, and the color was slightly darker after sonication at 35°C). The mixed solution was dispersed into 300 mg of ZIF-8 support (the mixed solution was added to the ZIF-8 support in 6 portions of 50 μL each time, and after each addition, it was ground evenly with a mortar and pestle (5 min) before the next addition. The color of the ZIF-8 support changed from white to light brownish-yellow). After stirring thoroughly to promote uniform adsorption of the ZIF-8 support material, the ZIF-8 support was pyrolyzed at a temperature of 900°C, a heating rate of 5°C / min, and a holding time of 2 h to obtain the FeGa / ZIF-8 catalyst.

[0041] (3) Characterization of the structure and morphology of the catalyst and performance testing.

[0042] (A) Structural morphology and elemental characterization of the catalyst:

[0043] The elemental composition of the FeGa / ZIF-8 catalyst was characterized using X-ray diffraction (XRD). Figure 1 ).from Figure 1 It can be seen that the prepared FeGa / ZIF-8 catalyst material only has a carbon peak, confirming that there is no metal peak in the support (in single-atom catalysts, metal elements exist as isolated single atoms, anchored to the support through coordination bonds, without a periodic lattice arrangement, therefore...). Figure 1 (No metal peaks were observed in the XRD).

[0044] The metal loading of the metal cluster catalyst was observed using aberration-corrected high-arc electron microscopy (HAADF-STEM). Figure 2 ).

[0045] (B) Cathode oxygen reduction catalytic performance test:

[0046] A three-electrode system was used to perform cyclic voltammetry scans in oxygen-saturated alkaline seawater electrolyte at a scan rate of 5 mV / s and an electrode rotation speed of 1600 r / min. The results are shown in [Figure number missing]. Figure 5 .

[0047] The catalyst prepared in this embodiment exhibits superior oxygen reduction catalytic activity compared to the 20% Pt / C catalyst (Hesen catalyst, product name: 20% platinum carbon, model: HPT020, purchased from: Shanghai Hesen Electric Co., Ltd.).

[0048] Unless otherwise specified, the test methods for the catalytic activity and stability of the catalysts involved in this application for cathode oxygen reduction are the same as those described above.

[0049] Example 2: ZIF-8 supported Fe metal cluster catalyst

[0050] (1) Preparation of ZIF-8 carrier: 4.464 g zinc nitrate hexahydrate was dissolved in 120 ml anhydrous methanol and sonicated for 20 min to obtain solution A; 4.928 g dimethylimidazole was dissolved in 120 ml to obtain solution B; solution A was quickly added to solution B under stirring conditions, stirred for 90 min and allowed to stand for 24 h to precipitate, washed and centrifuged three times with anhydrous methanol at 10500 rpm for 5 min, and then dried in an oven to obtain a typical ZIF-8 carrier.

[0051] (2) Preparation of Fe metal cluster catalyst: 16 mg of ferric chloride hexahydrate was dissolved in a mixed solvent (a 1:1 mixture of ethanol (400 μL) and water (400 μL) by volume), and sonicated at 35°C until homogeneous. Then 100 mg of cyanamide was added, and the mixture was sonicated at 35°C for 30 min to obtain a mixed solution (the mixed solution was light brownish-yellow after the addition of cyanamide, and the color was slightly darker after sonication). The mixed solution was dispersed into 300 mg of ZIF-8 support (the mixed solution was added dropwise in 6 portions of 50 μL each time to the ZIF-8 support. After each drop, the ZIF-8 support was ground evenly in a mortar (5 min) before the next drop was added. The color of the ZIF-8 support changed from white to light brownish-yellow). After stirring thoroughly to promote uniform adsorption of the ZIF-8 support material, the ZIF-8 support was pyrolyzed at a temperature of 900°C, a heating rate of 5°C / min, and a holding time of 2 h to obtain the Fe / ZIF-8 catalyst.

[0052] (3) Characterization of the structure and morphology of the catalyst and performance testing.

[0053] (A) Structural morphology and elemental characterization of the catalyst:

[0054] The elemental composition of the Fe / ZIF-8 catalyst was characterized using X-ray diffraction (XRD). Figure 1 ).from Figure 1 It can be seen that the prepared Fe / ZIF-8 catalyst material only has carbon peaks, confirming that no elemental metals exist in the support.

[0055] The metal loading of the Fe / ZIF-8 catalyst was observed using aberration-corrected high-arc electron microscopy (HAADF-STEM). Figure 3 ).

[0056] (B) Cathode oxygen reduction catalytic performance test:

[0057] The test method is described in Example 1, and the results are shown in [example 1]. Figure 5 .

[0058] Example 3: ZIF-8 supported Ga metal cluster catalyst

[0059] (1) Preparation of ZIF-8 carrier: 4.464 g zinc nitrate hexahydrate was dissolved in 120 ml anhydrous methanol and sonicated for 20 min to obtain solution A; 4.928 g dimethylimidazole was dissolved in 120 ml anhydrous methanol to obtain solution B; solution A was quickly added to solution B under stirring conditions, stirred for 90 min and allowed to stand for precipitation for 24 h, washed and centrifuged three times with anhydrous methanol at 10500 rpm for 5 min, and dried in an oven to obtain a typical ZIF-8 carrier.

[0060] (2) Preparation of Ga metal cluster catalyst: 9.6 mg of anhydrous gallium trichloride was dissolved in a mixed solvent (a 1:1 mixture of ethanol (400 μL) and water (400 μL) by volume), and sonicated at 35°C until homogeneous. Then, 100 mg of chelating agent was added, and the mixture was sonicated at 35°C for 30 min to obtain a mixed solution (the mixed solution was light brownish-yellow after the addition of the chelating agent, and the color was slightly darker after sonication at 35°C). The mixed solution was dispersed into 300 mg of ZIF-8 support (the mixed solution was added to the ZIF-8 support in 6 portions, 50 μL each time, and after each addition, it was ground evenly with a mortar (5 min) before the next addition. The color of the ZIF-8 support changed from white to light brownish-yellow). After stirring thoroughly to promote uniform adsorption of the ZIF-8 support material, the mixture was pyrolyzed at a temperature of 900°C, a heating rate of 5°C / min, and a holding time of 2 h to obtain the Ga / ZIF-8 catalyst.

[0061] (3) Characterization of the structure and morphology of the catalyst and performance testing.

[0062] (A) Structural morphology and elemental characterization of the catalyst:

[0063] The elemental composition of the Ga / ZIF-8 catalyst was characterized using X-ray diffraction (XRD). Figure 1 ).from Figure 1 It can be seen that the prepared Ga / ZIF-8 catalyst material only has carbon peaks, confirming that no elemental metals exist in the support.

[0064] The metal loading of the metal cluster catalyst was observed using aberration-corrected high-arc electron microscopy (HAADF-STEM). Figure 4 ).

[0065] (B) Cathode oxygen reduction catalytic performance test:

[0066] The test method is described in Example 1, and the results are shown in [example 1]. Figure 5 .

[0067] Comparative Example 1

[0068] Pt / C, Hesen catalyst, product name: 20% platinum carbon, model: HPT020, purchased from: Shanghai Hesen Electric Co., Ltd.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a metal cluster catalyst, characterized in that, Includes the following steps: At least one metal source is dissolved in a mixed solvent, sonicated to homogenize, and then a chelating agent is added. After sonication, a mixed solution is obtained. The mixed solution is dispersed in a support material, stirred thoroughly, and then pyrolyzed to obtain a metal cluster catalyst.

2. The method for preparing the metal cluster catalyst according to claim 1, characterized in that, The carrier material is selected from at least one of carbon nanotubes, graphene, Ketjen black, MOF materials, and COF materials, wherein the MOF material is ZIF-8 material.

3. The method for preparing the metal cluster catalyst according to claim 2, characterized in that, The preparation process of the ZIF-8 material is as follows: Zinc nitrate hexahydrate is dissolved in anhydrous methanol and ultrasonicated to obtain solution A; dimethylimidazole is dissolved in anhydrous methanol to obtain solution B; solution A is rapidly added to solution B under stirring conditions, stirred and allowed to stand to precipitate, washed with anhydrous methanol and centrifuged three times, placed in an oven and dried to obtain ZIF-8 material.

4. The method for preparing the metal cluster catalyst according to claim 3, characterized in that, The specific process of stirring and allowing the mixture to settle is as follows: stir for 90 minutes and then allow it to settle for 20-24 hours.

5. The method for preparing the metal cluster catalyst according to claim 1, characterized in that, The specific conditions for the pyrolysis are as follows: pyrolysis is carried out under flowing argon gas, the pyrolysis temperature is 900℃, the heating rate is 5℃ / min, and the holding time is 2h.

6. The method for preparing the metal cluster catalyst according to claim 1, characterized in that, The metal source is selected from at least one of the following: ferric chloride hexahydrate, anhydrous gallium trichloride, cobalt chloride, nickel chloride, palladium chloride, zinc chloride, tin chloride, manganese chloride, copper chloride, cobalt nitrate, ferric nitrate, nickel nitrate, manganese nitrate, and copper nitrate.

7. The method for preparing the metal cluster catalyst according to claim 1, characterized in that, The mixed solvent is composed of ethanol and water in a volume ratio of 1:

1.

8. The method for preparing the metal cluster catalyst according to claim 1, characterized in that, The chelating agent is cyanamide.

9. A metal cluster catalyst, characterized in that, Metal cluster catalysts prepared by the method according to any one of claims 1 to 8.

10. The application of the metal cluster catalyst according to claim 9 in a seawater zinc-air battery.

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