Carbon-based transition metal monatomic catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of new energy, and particularly relates to a carbon-based transition metal monatomic catalyst and a preparation method and application thereof. According to the preparation method provided by the invention, synthesis of the bimetallic ZIF material is matched with plasma calcination, so that the dispersity and stability of single atoms can be remarkably improved, the catalytic performance is further improved, and the service life is prolonged. The obtained catalyst shows better oxygen reduction performance than commercial Pt / C in an alkaline medium; metal single atoms are stably anchored to a carbon matrix, so that the corrosion resistance is high, and the performance attenuation in long-period circulation is small; the carbon-based structure is porous and is doped with nitrogen, so that the mass transfer effect is enhanced, and the stability is excellent. The three bottleneck problems of high cost, low performance and short service life in the development of the current zinc air battery are solved, and key material support is provided for a new generation of high-performance and low-cost energy storage devices.

Description

Technical Field

[0001] This application belongs to the field of new energy technology, specifically relating to a carbon-based transition metal single-atom catalyst, its preparation method, and its application. Background Technology

[0002] The development of new clean energy sources can effectively alleviate the depletion of fossil fuels and the resulting pollution problems. Among these, secondary batteries, represented by lithium-ion batteries, are widely used as energy storage devices. However, due to inherent safety issues and the limited reserves of lithium metal, the large-scale use of lithium metal will inevitably lead to a supply shortage of lithium salts. Zinc-air batteries, with their high energy density, excellent durability, and clean, pollution-free operation, can effectively solve the problems associated with lithium batteries. However, the slow multi-step electron transfer kinetics of oxygen during the charging and discharging process of rechargeable zinc-air batteries result in low round-trip energy efficiency, severely restricting their development.

[0003] Rechargeable zinc-air batteries convert chemical energy into electrical energy through redox reactions between an air electrode and oxygen. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are two key steps, but their kinetics are very slow, necessitating the design of highly efficient bifunctional catalysts. Currently, catalysts used in the ORR of zinc-air battery cathodes mainly include noble metal-based catalysts (such as Pt / C) and non-noble metal catalysts (such as Fe-NC and Co-NC). Although noble metal catalysts exhibit excellent catalytic performance, their high cost and scarcity limit their large-scale application; while traditional non-noble metal catalysts, although possessing certain activity, generally suffer from insufficient catalytic activity, uneven distribution of active sites, poor conductivity, and poor stability.

[0004] In recent years, single-atom catalysts (SACs) have attracted attention due to their high atomic utilization and well-defined active centers. However, existing methods for preparing single-atom catalysts either often require sophisticated high-energy physics techniques (such as atomic layer deposition and cryogenic ball milling), and their stability and catalytic performance still need improvement; or the single atoms in the catalyst are poorly dispersed, requiring acid washing to remove clustered single atoms, which damages the single-atom sites, affects catalytic performance, and generates acid washing wastewater, increasing post-treatment costs. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this application is to overcome the shortcomings of existing single-atom catalysts, which require high-end high-energy physical methods for preparation, still need to improve stability and catalytic performance, or have poor single-atom dispersion and require acid washing steps. This not only affects catalytic performance but also generates waste liquid and increases post-processing costs. Therefore, this application provides a carbon-based transition metal single-atom catalyst, its preparation method and application.

[0006] Therefore, this application provides the following technical solution:

[0007] According to one aspect of this application, a method for preparing a carbon-based transition metal single-atom catalyst is provided, comprising the following steps:

[0008] S1, zinc salt, transition metal salt, 2-methylimidazole and methanol are mixed and self-assembled to obtain bimetallic ZIF material;

[0009] S2 is subjected to plasma calcination under a protective atmosphere to obtain a carbon-based transition metal single-atom catalyst.

[0010] In some optional embodiments, in S2, the plasma calcination temperature is 800-1000℃, the calcination time is 30-60 min, and the power is 0.8-1.2 kW. For example, the plasma calcination temperature can be 800℃, 830℃, 850℃, 870℃, 900℃, 920℃, 950℃, 980℃, 1000℃, or any range of the above values; the calcination time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any range of the above values; and the power can be 0.8 kW, 0.85 kW, 0.9 kW, 0.95 kW, 1.0 kW, 1.05 kW, 1.1 kW, 1.15 kW, 1.2 kW, or any range of the above values.

[0011] In some alternative embodiments, the protective atmosphere includes at least one of argon and nitrogen.

[0012] In some alternative embodiments, in S1, the molar ratio of the zinc salt to the transition metal salt is 10:1 to 30:1; as an example, the molar ratio of the zinc salt to the transition metal salt can be 10:1, 12:1, 15:1, 18:1, 20:1, 23:1, 25:1, 27:1, 30:1, or within any of the above values.

[0013] In some alternative embodiments, the mass ratio of the zinc salt to 2-methylimidazole is 5:3 to 9. As an example, the mass ratio of the zinc salt to 2-methylimidazole can be 5:3, 5:4, 5:5, 5:5.5, 5:6, 5:6.5, 5:7, 5:8, 5:9, or within any range of the above values.

[0014] In this application, methanol in S1 is used as a solvent, and its amount is conventional in the art and is not specifically limited in this application.

[0015] In some alternative embodiments, in S1, the self-assembly reaction time is 6-24 hours. As an example, the self-assembly reaction time can be 6 hours, 10 hours, 12 hours, 16 hours, 20 hours, 22 hours, 24 hours, or within any range of the above values.

[0016] In this application, the self-assembly reaction is carried out at room temperature.

[0017] In some alternative embodiments, S1 further includes the steps of product separation, drying, and grinding after the self-assembly reaction.

[0018] In some alternative embodiments, the zinc salt comprises zinc nitrate;

[0019] In some optional embodiments, the transition metal in the transition metal salt includes at least one of Ni, Co, and Fe;

[0020] In some alternative embodiments, the transition metal salt includes at least one of transition metal sulfate, transition metal nitrate, transition metal chloride, and transition metal acetylacetone complex.

[0021] In some alternative embodiments, the grinding step controls the Dv50 particle size of the resulting bimetallic ZIF material to be 50-100 nm; as an example, the Dv50 particle size of the resulting bimetallic ZIF material controlled by the grinding step can be 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or within any range of the above values.

[0022] In some alternative embodiments, the transition metal salt includes at least one of ferrous sulfate, cobalt nitrate, nickel chloride, cobalt chloride, ferric acetylacetonate, and cobalt acetylacetonate.

[0023] According to another aspect of this application, a carbon-based transition metal single-atom catalyst is provided, which is prepared by the preparation method described above in this application.

[0024] According to another aspect of this application, a zinc-air battery is provided, comprising the aforementioned carbon-based transition metal single-atom catalyst.

[0025] According to another aspect of this application, an electrical device is provided, including the zinc-air battery described above.

[0026] In this application, the high specific surface area and abundant N source of ZIF material are used to achieve stable anchoring of metal single atoms. Plasma calcination can significantly improve the dispersion of single atoms. Control of carbonization temperature can avoid the formation of metal clusters into nanoparticles, avoid the damage of acid washing to single atom sites, and improve catalytic performance. At the same time, the omission of the acid washing step avoids the damage to single atom sites and the generation of acid washing waste liquid, and eliminates the need for post-treatment steps.

[0027] In this application, by controlling the proportion of transition metal doping, the single-atom dispersion can be further improved.

[0028] In this application, the term "plasma calcination" refers to heating using plasma during the calcination process.

[0029] The carbon-based transition metal single-atom catalyst provided in this application can replace the noble metal-based catalyst Pt / C as a cathode material in zinc-air batteries, exhibiting excellent electrochemical properties such as conductivity, chemical stability, corrosion resistance, and cycle life. Furthermore, the catalyst provided in this application can also be used as a cathode material for fuel cells: suitable for oxygen reduction reactions in alkaline or neutral media; as an electrode material for supercapacitors: utilizing its high specific surface area and good electrical conductivity as an energy storage material; as a power supply system for wearable electronic devices: combining with flexible zinc-air battery structures to improve battery life; as an auxiliary energy system for electric vehicles: applied to secondary energy recovery and low-speed cruising energy modules; and as a low-cost energy solution for homes or remote areas in distributed energy systems.

[0030] Those skilled in the art will understand that the materials, composition, and manufacturing methods used in the zinc-ion batteries provided in this application may include any techniques disclosed in the prior art.

[0031] It is understood that in the electrical equipment provided in this application, the zinc-ion battery can be used as a power source for the electrical equipment, or as an energy storage unit for the electrical equipment. The electrical equipment may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0032] The technical solution of this application has the following advantages:

[0033] The preparation method of the carbon-based transition metal single-atom catalyst provided in this application includes the following steps: S1, mixing zinc salt, transition metal salt, 2-methylimidazole and methanol to carry out a self-assembly reaction to obtain a bimetallic ZIF material; S2, performing plasma calcination under a protective atmosphere to obtain the carbon-based transition metal single-atom catalyst. The preparation method provided in this application, through the synthesis of the bimetallic ZIF material and its combination with plasma calcination, can significantly improve the dispersion and stability of single atoms, thereby enhancing catalytic performance and extending service life. Plasma calcination significantly improves the dispersion of single atoms, eliminating the need for subsequent acid washing steps, avoiding damage to single-atom sites during acid washing, and improving catalytic performance. Furthermore, omitting the acid washing step fundamentally avoids the generation of acid washing waste liquid, eliminating the cost increase caused by post-processing steps. The obtained catalyst exhibits superior oxygen reduction performance compared to commercial Pt / C in alkaline media; the metal single atoms are stably anchored to the carbon matrix, exhibiting strong corrosion resistance and minimal performance decay during long-term cycling; the porous carbon-based structure with nitrogen doping is beneficial for enhancing mass transfer and possesses excellent stability. This application addresses the three major bottlenecks currently facing the development of zinc-air batteries: high cost, low performance, and short lifespan, providing key material support for next-generation high-performance, low-cost energy storage devices. Furthermore, the preparation method described in this application is environmentally friendly and low-cost, using inexpensive raw materials and mild synthesis conditions, which is conducive to industrial production.

[0034] The zinc-air battery and electrical equipment provided in this application have the same advantages as the aforementioned carbon-based transition metal single-atom catalysts because they employ the carbon-based transition metal single-atom catalyst provided in this application, which will not be elaborated here.

[0035] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments 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.

[0037] Figure 1 These are the spherical aberration electron microscopy test results of the catalysts obtained in Example 1 and Comparative Example 1 of this application;

[0038] Figure 2 This is a comparison chart of the catalytic performance of the catalysts obtained in Example 1 and Comparative Example 1 of this application. Detailed Implementation

[0039] The following embodiments are provided to better understand this application and are not limited to the preferred embodiments described herein. They do not constitute a limitation on the content and scope of protection of this application. Any product that is the same as or similar to this application, derived by anyone under the guidance of this application or by combining features of this application with other prior art, falls within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0044] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0045] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0048] Example 1

[0049] This embodiment provides a carbon-based transition metal single-atom catalyst, the composition of which and its preparation method are as follows:

[0050] S1, 3.0 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and ferrous sulfate heptahydrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to ferrous sulfate heptahydrate of 20:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation and finally dried at 60 °C for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0051] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 900°C for 0.5 h at a power of 1 kW to obtain a carbon-based transition metal single-atom catalyst.

[0052] Example 2

[0053] This embodiment provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that: an equimolar amount of nickel chloride is used instead of ferrous sulfate heptahydrate.

[0054] S1, 3.0 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and nickel chloride was added to solution A, with a molar ratio of zinc nitrate hexahydrate to nickel chloride of 20:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation, and finally dried at 60 °C for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0055] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 900°C for 0.5 h at a power of 1 kW to obtain a carbon-based transition metal single-atom catalyst.

[0056] Example 3

[0057] This embodiment provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that: an equimolar amount of cobalt nitrate is used instead of ferrous sulfate heptahydrate.

[0058] S1, 3.0 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and cobalt nitrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to cobalt nitrate of 20:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation, and finally dried at 60 °C for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0059] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 900°C for 0.5 h at a power of 1 kW to obtain a carbon-based transition metal single-atom catalyst.

[0060] Example 4

[0061] This embodiment provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that the plasma calcination parameters in S2 are different, specifically:

[0062] S1, 3.0 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and ferrous sulfate heptahydrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to ferrous sulfate heptahydrate of 20:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation and finally dried at 60 °C for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0063] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 800°C for 1 hour at a power of 0.8 kW to obtain a carbon-based transition metal single-atom catalyst.

[0064] Example 5

[0065] This embodiment provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that the plasma calcination parameters in S2 are different, specifically:

[0066] S1, 3.0 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and ferrous sulfate heptahydrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to ferrous sulfate heptahydrate of 20:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation and finally dried at 60 °C for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0067] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 1000℃ for 40 min at a power of 1.2 kW to obtain a carbon-based transition metal single-atom catalyst.

[0068] Example 6

[0069] This embodiment provides a carbon-based transition metal single-atom catalyst, the composition of which and its preparation method are as follows:

[0070] S1, 1.5 g of 2-methylimidazole was dissolved in 150 mL of methanol to obtain solution A. 200 mL of methanol solution containing 2.5 g of zinc nitrate hexahydrate and ferrous sulfate heptahydrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to ferrous sulfate heptahydrate of 15:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation and finally dried at 60 °C for 10 hours to obtain crystalline particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65 nm.

[0071] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 900°C for 0.5 h at a power of 1 kW to obtain a carbon-based transition metal single-atom catalyst.

[0072] Example 7

[0073] This embodiment provides a carbon-based transition metal single-atom catalyst, the composition of which and its preparation method are as follows:

[0074] S1, 4g of 2-methylimidazole was dissolved in 150mL of methanol to obtain solution A. 200mL of methanol solution containing 2.5g of zinc nitrate hexahydrate and ferrous sulfate heptahydrate was added to solution A, with a molar ratio of zinc nitrate hexahydrate to ferrous sulfate heptahydrate of 28:1, forming solution B. The resulting pale yellow solution B was magnetically stirred at room temperature for 24 hours to carry out the coordination self-assembly reaction between the metal node and the organic ligand. After 24 hours of stirring, a pale yellow precipitate was collected by centrifugation and finally dried at 60℃ for 10 hours to obtain crystal particles (bimetallic ZIF material). The particles were then ground to control the Dv50 particle size to 65nm.

[0075] S2, In a nitrogen atmosphere, the bimetallic ZIF material precursor obtained in the above steps is subjected to high-temperature plasma calcination at 900°C for 0.5 h at a power of 1 kW to obtain a carbon-based transition metal single-atom catalyst.

[0076] Comparative Example 1

[0077] This comparative example provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that: a tube furnace calcination is used instead of plasma calcination, the calcination temperature is 900℃, and the calcination time is 0.5h.

[0078] Comparative Example 2

[0079] This comparative example provides a carbon-based transition metal single-atom catalyst, which differs from Example 1 in that it uses an equimolar amount of ferrocyanine instead of ferrous sulfate.

[0080] Test case

[0081] The carbon-based transition metal single-atom catalysts provided in each embodiment and comparative example were subjected to various performance tests. The specific test methods are as follows:

[0082] 1. Metal atom dispersion test

[0083] The results of spherical aberration electron microscopy tests for Example 1 and Comparative Example 1 are as follows: Figure 1 As shown, Figure 1 Figure a shows the test results of Comparative Example 1, and figure b shows the test results of Example 1. As can be seen from the figures, the iron element in Comparative Example 1 forms clustered particles with poor dispersibility; while the iron element in Example 1 is more uniformly dispersed on the carrier surface. The test results of other examples are similar to those of Example 1, and will not be shown one by one.

[0084] 2. Oxygen reduction performance

[0085] The ORR catalytic performance of the catalysts provided in each example and comparative example was tested using a standard three-electrode system on an electrochemical workstation. Hg / HgO (reference electrode, saturated potassium hydroxide aqueous solution) and a graphite rod electrode were used as the reference and counter electrodes, respectively, and the working electrode was a catalyst-modified glassy carbon electrode (GC, 0.24 cm⁻¹). 2 The glassy carbon electrode was modified with 20 μL of a catalyst dispersion with a concentration of 5 mg / mL. Its ORR performance was tested in oxygen-saturated 0.1 M KOH. The LSV test scan rate was 10 mV / s, and the rotation speed was 160 rpm. The test results of Example 1 and Comparative Example 1 are shown below. Figure 2 The specific test results of other embodiments and comparative examples are shown in the table below:

[0086] Table 1

[0087]

[0088]

[0089] As can be seen from the test results in the table above, the carbon-based transition metal single-atom catalyst provided in this application embodiment can significantly improve the dispersion and catalytic performance of single atoms through the synthesis of bimetallic ZIF materials and the combination with plasma calcination. It eliminates the need for an acid washing step, thereby avoiding the generation of waste acid and the increase in post-processing costs.

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a carbon-based transition metal single-atom catalyst, characterized in that, The method comprises the following steps: S1, mixing zinc salt, transition metal salt, 2-methyl imidazole and methanol to carry out self-assembly reaction to obtain a bimetallic ZIF material; S2, carrying out plasma calcination under a protective atmosphere to obtain a carbon-based transition metal monatomic catalyst.

2. The method of preparing a carbon-based transition metal single-atom catalyst according to claim 1, wherein, In S2, the temperature of the plasma calcination is 800-1000℃, the calcination time is 30-60min, and the power is 0.8-1.2kW. And / or, the protective atmosphere comprises at least one of argon and nitrogen.

3. The method of producing a carbon-based transition metal single-atom catalyst according to claim 1, wherein, In S1, the molar ratio of the zinc salt to the transition metal salt is 10:1-30:

1. And / or, the mass ratio of the zinc salt to 2-methyl imidazole is 5:3-9.

4. The method of producing a carbon-based transition metal single-atom catalyst according to claim 1, wherein In S1, the self-assembly reaction time is 6-24h.

5. The method of producing a carbon-based transition metal single-atom catalyst according to claim 1, wherein In S1, the self-assembly reaction further comprises the steps of product separation, drying and grinding.

6. The method of producing a carbon-based transition metal single-atom catalyst according to claim 5, wherein, The zinc salt comprises zinc nitrate. And / or, the transition metal in the transition metal salt comprises at least one of Ni, Co and Fe. And / or, the transition metal salt comprises at least one of a transition metal sulfate, a transition metal nitrate, a transition metal chloride and a transition metal acetylacetone complex.

7. The method of producing a carbon-based transition metal single-atom catalyst according to claim 6, wherein The grinding step controls the Dv50 particle size of the obtained bimetallic ZIF material to be 50-100nm. And / or, the transition metal salt comprises at least one of ferrous sulfate, cobalt nitrate, nickel chloride, cobalt chloride, acetylacetone iron and acetylacetone cobalt.

8. A carbon-based transition metal single-atom catalyst characterized in that, Prepared by the preparation method in any one of claims 1-7.

9. A zinc-air battery, characterized by, The carbon-based transition metal monatomic catalyst in claim 8.

10. An electric device, characterized by The zinc-air battery in claim 9.

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